JP5481316B2 - Zirconia sintered body, and composition for sintering and calcined body - Google Patents

Description

  The present invention relates to a zirconia sintered body. The present invention also relates to a composition for sintering a zirconia sintered body and a calcined body.

Zirconium oxide (IV) (ZrO ₂ ) (hereinafter referred to as “zirconia”) has polymorphs, and zirconia causes a phase transition between the polymorphs. For example, tetragonal zirconia undergoes a phase transition to monoclinic crystals. For this reason, even if a sintered body is made of zirconia alone, the crystal structure is destroyed by this phase transition, so that the sintered body of zirconia alone has a drawback that sufficient strength as a product cannot be secured. Moreover, the sintered body of a zirconia single-piece | unit has the fault that the dimension of a sintered compact will change by the volume change by a phase transition.

  Therefore, stabilized zirconia or partially stabilized zirconia (PSZ; which suppresses the occurrence of phase transition by adding an oxide such as calcium oxide, magnesium oxide, yttrium oxide, or cerium oxide as a stabilizer to zirconia. Partially Stabilized Zirconia) is used. In particular, partially stabilized zirconia is a ceramic having excellent properties such as high strength and high toughness, and sintered parts of partially stabilized zirconia are used in various applications such as prosthetic materials and tools used for tooth treatment, for example. Is used.

  However, since partially stabilized zirconia is only partially stabilized, the problem of long-term stability has not been solved. For example, in the partially stabilized zirconia sintered body, when it is heated to about 200 ° C. in the presence of moisture, a phase transition from tetragonal to monoclinic crystal occurs. The strength deteriorates (hereinafter referred to as “low temperature deterioration”). Then, the manufacturing technique of the zirconia sintered compact which suppresses low temperature deterioration is developed (for example, refer patent document 1-patent document 6).

  In the background art related to Patent Document 1 and Patent Document 2, using a partially stabilized zirconia fine powder having an average particle size of 0.5 μm or less, the zirconia fine powder is sintered at 1200 ° C. to 1400 ° C. Manufactures knots.

In the background art according to Patent Document 3 and Non-Patent Document 1, in order to obtain a zirconia sintered body that does not cause a low temperature deterioration phenomenon, Y or the like is formed on the surface of a green compact of zirconia material containing Y ₂ O ₃ or the like. A zirconia sintered body is manufactured by applying a solution containing the above compound and firing at 1300 to 1800 ° C.

The zirconia sintered body described in Patent Document 4 includes zirconia containing ZrO ₂ , rare earth metal oxides (R ₂ O ₃ ) such as Y ₂ O ₃ , boron compounds, SiO _2, and Al ₂ O _3. a sintered body, ZrO ₂ and rare earth metal oxides _(R 2 _{O 3)} and boron compound and molar ratio of _Al 2 _{O 3} with respect to the component (M) that includes a _{SiO 2 (Al 2 O 3 /} M) is 10/90 to 50/50, the molar ratio of the rare earth metal oxide (R ₂ O ₃ ) to ZrO ₂ (R ₂ O ₃ / ZrO ₂ ) is 1/99 to 6/94, and ZrO The crystal grains of ₂ mainly comprise a tetragonal phase or a mixed phase of tetragonal and cubic crystals, and the content of boron (B) with respect to the total of ZrO ₂ and rare earth metal oxide (R ₂ O ₃ ) is 0.05. ˜2 mol%, SiO ₂ content is 0.05 to 1.5 mol% The The zirconia medical material described in Patent Document 5 is mainly composed of ZrO ₂ , an oxide of a rare earth metal such as Y ₂ O ₃ , a boron compound, and Al ₂ O ₃ and / or SiO ₂ . And the molar ratio of the rare earth metal oxide to ZrO ₂ is 1.5 / 98.5 to 5/95, and the boron compound content is 0.05 to 8% mol in terms of boron (B). %, Al ₂ O ₃ content is 0.1 to 5 mol%, and SiO ₂ content is 0.05 to 1.5 mol%.

The zirconia ceramic described in Patent Document 6 is partially stabilized in which the molar ratio of Y ₂ O ₃ and ZrO ₂ is in the range of 2/98 to 4.5 / 95.5, and the crystal form is mainly composed of tetragonal grains. Zirconia is 93% by weight or more, and the balance contains at least one oxide selected from boron oxide, germanium oxide, and gallium oxide, and the content of boron oxide is 1% by weight or less. Stable at temperatures of

  Patent Document 7 discloses a dental processing block for manufacturing a frame material having bending strength that is easy to grind and grind after complete sintering and can be applied to a bridge having a large number of teeth. Yes. The dental processing block described in Patent Document 7 is a complete sintered body of a metal oxide mainly composed of at least one of zirconia, alumina, mullite, and spinel. 1 to 23 parts by mass of lanthanum phosphate and / or aluminum phosphate is included as a crystal.

JP 2001-80962 A JP 2007-332026 A JP-A-3-115166 JP 7-215758 A JP-A-8-33701 JP-A-4-349172 JP 2009-23850 A Yasuji Yamamoto, Ichiro Kakei, “Improvement of heat resistance by surface modification of Y-TZP”, Zirconia ceramics 13 and 14, Uchida Otsukuru, 1998, pp. 147-163

  The following analysis is given from the perspective of the present invention.

  Zirconia sintered bodies containing many monoclinic phase transitions from tetragonal crystals and zirconia sintered bodies with a rapid phase transition from tetragonal to monoclinic crystals cannot secure sufficient strength, for example, risk of damage Therefore, high reliability as an industrial product (for example, a dental prosthetic material) cannot be ensured.

  In the background art described in Patent Document 1 and Patent Document 2, the partially stabilized zirconia particles are made very fine so as to be easily sintered, and sintered at a low temperature of 1200 ° C. to 1400 ° C. to obtain a zirconia sintered body. It has gained. However, in order to increase the strength and dimensional stability of the zirconia sintered body, it is required to sinter at a higher temperature.

  Therefore, when the partially stabilized zirconia particles are sintered at a high temperature (for example, a temperature exceeding 1400 ° C.) in order to increase the strength of the zirconia sintered body, the fine partially stabilized zirconia as described in Patent Document 1 and Patent Document 2 is used. Even if the particle raw material is used, this sintered body is likely to proceed with low temperature deterioration. Such a sintered body has problems in terms of strength maintenance and product life. Furthermore, since the dimensional change occurs as the phase transition progresses, it cannot be used for products that require high accuracy.

  Moreover, in the background art described in Patent Document 1 and Patent Document 2, the limited particle size of the partially stabilized zirconia particles restricts the production of the sintered body and confirms the reliability of the sintered body. For this purpose, the particle size of the raw material particles must be measured before the sintered body is produced.

  In the background art described in Patent Literature 3 and Non-Patent Literature 1, a cubic crystal is formed in the vicinity of the surface of the zirconia sintered body by applying a solution of a compound containing yttria (Y) or the like to the green surface. Yes. At this time, the cubic crystal is formed from the fired surface to a region having a depth of 200 μm or more. The particles on the fired surface have grown from a particle size of about 0.3 μm to about 2.5 μm. For this reason, a zirconia sintered body with high bending strength and high fracture toughness cannot be obtained. Furthermore, in the methods disclosed in Patent Document 3 and Non-Patent Document 1, it is necessary to use a stabilizer applied to the surface in addition to the stabilizer contained in the raw material powder every time a cubic crystal is to be formed. . Stabilizers using rare earth elements are expensive and particularly expensive to apply, which increases production costs.

  In the background art described in Patent Document 4, a zirconia sintered body having sufficient bending strength and fracture toughness cannot be obtained. On the other hand, the crystal system of crystal grains in the zirconia sintered body described in Patent Document 5 is a tetragonal crystal or a mixed phase of tetragonal crystal and cubic crystal. When the zirconia sintered body contains a cubic crystal in its interior, the bending strength and fracture toughness are lowered. Accordingly, no zirconia sintered body described in Patent Document 5 has high bending strength and high fracture toughness.

  In the zirconia ceramics described in Patent Document 6, the progress of the phase transition is observed despite the mild hydrothermal treatment conditions, and the low-temperature deterioration is not sufficiently suppressed.

  The dental processing block described in Patent Document 7 obtains a zirconia sintered body that is easy to grind and grind, but the manufacturing method of the sintered body is the same as in Patent Document 1 and Patent Document 2. Have the same problems as the techniques described in Patent Document 1 and Patent Document 2.

  On the other hand, in fully stabilized zirconia, although the phase transition to monoclinic crystal can be suppressed, the toughness and strength are lower than in partially stabilized zirconia.

  Further, in order to use the zirconia sintered body as a dental prosthetic material, in addition to strength, it is required to be colorless and translucent, but coloring may occur depending on the stabilizer. Or transparency may be lost.

  Therefore, the present inventors include a predetermined amount of phosphorus element such as phosphorus, and are not limited to the particle size of the raw material particles, and zirconia sintering in which the progress of low temperature deterioration is suppressed even at high temperature sintering. Invented the body (see Japanese Patent Application No. 2009-192287). In the invention, the effect of suppressing the low temperature deterioration can be enhanced as the sintering is performed at a higher temperature. On the other hand, when the sintering was performed at a temperature lower than 1500 ° C. or less, the low-temperature deterioration suppressing effect tended to decrease.

  The objective of this invention is providing the zirconia sintered compact which can suppress low-temperature deterioration even if it sinters at low temperature. Another object of the present invention is to provide a zirconia sintered body having high strength and high fracture toughness even when sintered at a low temperature. Furthermore, an object of the present invention is to provide a sintering composition and a calcined body that are precursors of the zirconia sintered body.

According to the 1st viewpoint of this invention, it has a partly stabilized zirconia as a matrix phase, and boron (B) element is 3 * 10 <^-4> mass% ^-3 * 10 < ^- > with respect to the mass of a zirconia sintered compact. A zirconia sintered body containing ¹ % by mass is provided. Zirconia sintered body, bismuth (Bi) elements, tin (Sn) element,及 beauty further contain at least one element of sulfur (S) element, when containing bismuth, the mass of the zirconia sintered body If it contained 0.001 wt% to 1 wt% for the case containing tin element, which contains 0.001 wt% to 1% by weight, based on the weight of the zirconia sintered body, containing sulfur element, containing 0.001% by mass to 0.1% by weight, based on the weight of the zirconia sintered body.

  According to a preferred embodiment of the first aspect, the zirconia sintered body further contains a phosphorus (P) element in an amount of 0.005% by mass to 1% by mass with respect to the mass of the zirconia sintered body.

  According to the preferable form of the said 1st viewpoint, a zirconia sintered compact further contains 0.2 mass%-25 mass% of aluminum oxide with respect to the mass of a zirconia sintered compact.

  According to the preferable form of the said 1st viewpoint, a zirconia sintered compact further contains 0.03 mass%-3 mass% of silicon dioxide with respect to the mass of a zirconia sintered compact.

  According to the preferred embodiment of the first aspect, a cubic [200] peak is generated in the X-ray diffraction pattern on the fired surface with respect to the height of the peak existing near the position where the tetragonal [200] peak occurs. The ratio of the heights of the peaks existing in the vicinity of the position is 0.4 or more. In the X-ray diffraction pattern in the region where the depth from the fired surface is 100 μm or more, near the position where the cubic [200] peak occurs relative to the height of the peak existing near the position where the tetragonal [200] peak occurs The ratio of the heights of the peaks existing in is 0.3 or less.

  According to the preferred form of the first aspect, the fired surface or the exposed surface is cut, and the X-ray diffraction pattern is derived from a cubic crystal with respect to the height of the peak existing near the position where the [200] peak derived from the tetragonal crystal is generated. [200] When a surface having a peak height ratio near the position where the peak occurs is exposed to 0.3 or less and then refired, in the X-ray diffraction pattern on the refired surface, tetragonal-derived [ 200] The ratio of the height of the peak existing near the position where the [200] peak derived from the cubic crystal to the height of the peak existing near the position where the peak occurs is 0.4 or more.

  According to the preferred embodiment of the first aspect, in the X-ray diffraction pattern in the region where the depth from the refired surface is 100 μm or more, the height of the peak existing near the position where the [200] peak derived from the tetragonal crystal occurs. The ratio of the heights of the peaks existing near the position where the [200] peak derived from the cubic crystal occurs is 0.3 or less.

  According to a preferred embodiment of the first aspect, when the zirconia sintered body is subjected to a low temperature deterioration accelerated test for 5 hours under the conditions of 180 ° C. and 1 MPa, X-rays on the surface of the zirconia sintered body after the low temperature deterioration accelerated test are obtained. In the diffraction pattern, the ratio of the height of the peak existing near the position where the [11-1] peak derived from the monoclinic crystal to the height of the peak existing near the position where the [111] peak derived from the tetragonal crystal is 1 is 1. It is as follows.

  According to a preferred embodiment of the first aspect, the zirconia sintered body is sintered at 1350 ° C. to 1550 ° C.

According to the second aspect of the present invention, it contains partially stabilized zirconia particles and contains boron (B) element in an amount of 4 × 10 ⁻⁵ mol to ⁵ × 10 ⁻² mol with respect to 1 mol of zirconium (IV) oxide. A composition for sintering a zirconia sintered body is provided. Sintering the composition of the zirconia sintered body of bismuth (Bi) elements, if the tin (Sn) element contains at least one element of 及 beauty sulfur (S) element, containing bismuth, zirconium oxide ^{(IV) 6 × 10 -6 mol~7} × 10 -3 mol contain against 1 mol, when containing tin element, 1 × ¹⁰ -5 with respect to zirconium (IV) 1mol mol~2 × 10 ^{- 2} mol contain, if containing sulfur element, zirconium oxide (IV) 4 × respect ^{1mol 10 -5 mol~5 × 10 - 3} mol contain.

  According to the 3rd viewpoint of this invention, the composition for sintering of the zirconia sintered compact from which the zirconia sintered compact which concerns on the said 1st viewpoint is obtained by sintering at 1350 degreeC-1650 degreeC is provided.

According to the 4th viewpoint of this invention, the zirconia containing a stabilizer is contained, and a boron (B) element is 4 * 10 < ^-5 > mol- ⁵ * 10 ^<-2 > mol with respect to 1 mol of zirconium oxide (IV). A calcined body of the zirconia sintered body to be contained is provided. Calcined body of zirconia sintered body, if bismuth (Bi) elements, tin (Sn) element contains at least one element of 及 beauty sulfur (S) element, containing bismuth, zirconium oxide (IV ) When containing 6 × 10 ⁻⁶ mol to 7 × 10 ⁻³ mol with respect to 1 mol and containing tin element, 1 × 10 ⁻⁵ mol to ² × 10 ⁻² mol with respect to 1 mol of zirconium (IV) oxide contains, if containing sulfur element, zirconium oxide (IV) 4 × respect ^{1mol 10 -5 mol~5 × 10 - 3} mol contain.

  According to the 5th viewpoint of this invention, the calcination body of the zirconia sintered compact used as the zirconia sintered body which concerns on the said 1st viewpoint by sintering at 1350 degreeC-1550 degreeC is provided.

  According to a sixth aspect of the present invention, there is provided a calcined body of a zirconia sintered body formed by calcining the sintering composition according to the second or third viewpoint at 800 ° C. to 1200 ° C. The

  The zirconia sintered body of the present invention includes not only a sintered body obtained by sintering molded zirconia particles under normal pressure or non-pressurization, but also HIP (Hot Isostatic Pressing) treatment. The sintered compact densified by high-temperature pressurization processes, such as, is also contained.

  In the present invention, the “low temperature deterioration acceleration test” refers to a test based on ISO13356. However, the conditions specified in ISO 13356 are “134 ° C., 0.2 MPa, 5 hours”. However, in the present invention, the conditions are set to “180 ° C., 1 MPa in order to make the acceleration test conditions more severe. The test time is set appropriately according to the purpose. Hereinafter, the “low temperature deterioration acceleration test” is also referred to as “hydrothermal treatment” or “hydrothermal treatment test”.

  The present invention has at least one of the following effects.

  According to the present invention, it is possible to obtain a zirconia sintered body having long-term stability in which low-temperature deterioration is suppressed even when sintered at a low temperature (for example, 1500 ° C. or less). Thereby, a zirconia sintered compact can be manufactured more cheaply.

  According to the present invention, the stabilizer in the raw material moves to the surface during firing. Thereby, only in the very thin area | region of a calcination surface, a stabilizer becomes high concentration and the cubic crystal increases in the area | region. On the other hand, since the stabilizer concentrates only on the fired surface, the stabilizer concentration inside the zirconia sintered body does not change greatly, and the crystal system inside the zirconia sintered body maintains a tetragonal crystal. be able to. That is, according to the present invention, it is possible to form a coating of a layer containing a large amount of cubic crystals only on the fired surface of the zirconia sintered body. It is considered that this layer containing a lot of cubic crystals can suppress the low-temperature degradation of the zirconia sintered body by hydrothermal treatment.

  Since the tetragonal crystal system is maintained in the zirconia sintered body, the bending strength and fracture toughness are not lowered. Furthermore, it is possible to obtain a zirconia sintered body in which both bending strength and fracture toughness, which are generally in an inversely proportional relationship, are improved.

  Thereby, the zirconia sintered compact of this invention can be utilized for the product for which high reliability and long life are requested | required. Furthermore, since the dimensional change due to the phase transition is also reduced, the zirconia sintered body of the present invention can be used for products that require high accuracy.

  In the present invention, it is not necessary to separately apply a stabilizer to the surface in order to make many cubic crystals exist on the fired surface, and it is only necessary to add an inexpensive additive and fire, so that the manufacturing cost increases. There is nothing.

  The zirconia sintered body of the present invention can form a cubic crystal again in the vicinity of the refired surface (exposed surface) by firing again even if the fired surface is processed to expose the tetragonal surface. As a result, by processing the sintered body into a desired shape, even if a surface whose main crystal system is tetragonal is exposed, it can be coated again with a layer containing cubic crystals by refiring. A product in which the progress of hydrothermal degradation is suppressed can be produced.

  As described above, according to the present invention, it is possible to obtain a zirconia sintered body having low-temperature deterioration property, high strength, and high fracture toughness without increasing the manufacturing cost. Moreover, this can be achieved regardless of the shape including the case of a complicated shape.

  In the present invention, a zirconia sintered body having needle-like crystals or columnar crystals that function as reinforcing fibers can be obtained. Thereby, even if it sinters at low temperature (for example, 1500 degrees C or less), the intensity | strength of a zirconia sintered compact can be raised.

  The zirconia sintered body of the present invention has colorlessness and translucency, and can be used for products that require transparency such as dental prosthetic materials.

The X-ray-diffraction pattern of the baking surface of the zirconia sintered compact of the addition rate of 0.2% of bismuth in Example 4, and the addition rate of boron oxide 0.1%. The X-ray-diffraction pattern inside the zirconia sintered compact of the addition rate of 0.2% of bismuth in Example 4, and the addition rate of boron oxide 0.1%. The X-ray-diffraction pattern of the re-baking surface of the zirconia sintered compact of the bismuth addition rate 0.2% in Example 4, and the boron oxide addition rate 0.1%. The X-ray-diffraction pattern of the baking surface of the zirconia sintered compact of the addition rate of tin 0.2% and the addition rate of boron oxide 0.1% in Example 8. The X-ray-diffraction pattern inside the zirconia sintered compact of the addition rate of 0.2% in Example 8, and the addition rate of boron oxide 0.1%. The X-ray-diffraction pattern of the rebaking surface of the zirconia sintered compact of the addition rate of tin 0.2% in Example 8, and the addition rate of boron oxide 0.1%. The X-ray-diffraction pattern of the baking surface of the zirconia sintered compact of the addition rate of germanium in Example 7, and the addition rate of boron oxide 0.1%. The X-ray-diffraction pattern inside the zirconia sintered compact of the addition rate of 0.2% of germanium in Example 7, and the addition rate of boron oxide 0.1%. The X-ray-diffraction pattern of the re-baking surface of the zirconia sintered compact in which the addition rate of germanium in Example 7 and the addition rate of boron oxide are 0.1%. The X-ray-diffraction pattern of the baking surface of the zirconia sintered compact of the addition rate of 0.2% of sulfur in Example 10, and the addition rate of boron oxide 0.1%. The X-ray-diffraction pattern inside the zirconia sintered compact of the addition rate of 0.2% in Example 10, and the addition rate of boron oxide 0.1%. The X-ray-diffraction pattern of the re-baking surface of the zirconia sintered compact of the addition rate of sulfur 0.2% and the addition rate of boron oxide 0.1% in Example 10. FIG. The X-ray-diffraction pattern of the baking surface of the zirconia sintered compact of the addition rate 0% of the comparative example 1 and the addition rate 0% of a boron oxide. The X-ray-diffraction pattern inside the zirconia sintered compact of the addition rate 0% of the comparative example 1 and the addition rate of boron oxide 0%. The X-ray-diffraction pattern of the re-fired surface of the zirconia sintered compact of the addition rate of 0% and the addition rate of boron oxide of 0% in the comparative example 1. The graph which plotted the peak ratio of the monoclinic crystal with respect to the addition rate of the boron oxide in Examples 1-4. The graph which plotted the peak ratio of the monoclinic crystal with respect to the addition rate of the boron oxide in Examples 6-9. The graph which plotted the peak ratio of the monoclinic crystal with respect to the addition rate of the boron oxide in Examples 11-13. The graph which plotted the peak ratio of the monoclinic crystal with respect to the addition rate of the boron oxide in Examples 15-17.

  The contents of claims, specifications, drawings, and abstracts of Japanese Patent Application Nos. 2009-192287, 2010-44967, and 2010-185586 are incorporated herein by reference.

  The zirconia sintered body according to the first embodiment of the present invention will be described. The zirconia sintered body of the present invention is a sintered body in which partially stabilized zirconia crystal particles are mainly sintered, and has partially stabilized zirconia as a matrix phase. Examples of the stabilizer in the partially stabilized zirconia crystal particles include oxides of oxides such as calcium oxide, magnesium oxide, yttrium oxide, and cerium oxide. The stabilizer is preferably added in such an amount that the zirconia particles can be partially stabilized. For example, when yttrium oxide is used as the stabilizer, the content of yttrium oxide is preferably 2 mol% to 5 mol% (about 3 mass% to 9 mass%) with respect to the partially stabilized zirconium oxide in the entire zirconia sintered body. %) Can be added. The content of the stabilizer in the zirconia sintered body can be measured, for example, by inductively coupled plasma (ICP) emission spectroscopy.

  The stabilizer is present on the fired surface of the zirconia sintered body in such a content that the fired surface can be completely stabilized, and within the zirconia sintered body (region other than the fired surface) It exists in such a content rate that it is partially stabilized. That is, it is considered that the zirconia sintered body has a region where the content of the stabilizer is attenuated from the fired surface of the zirconia sintered body toward the inside. This region is considered to be, for example, a region of 4 μm to 8 μm from the fired surface according to secondary ion mass spectrometry (SIMS). Further, according to X-ray photoelectron spectroscopy (XPS), for example, in the region from the fired surface to at least 5 nm, the stabilizer has a content of 5 mol% or more, more preferably 8 mol. % Or more. Further, for example, the content of the stabilizer in the interior from the depth of 100 μm from the fired surface of the zirconia sintered body is preferably 2 mol% to less than 5 mol%, and more preferably 4 mol% or less. As a method of increasing the content of the stabilizer on the fired surface of the zirconia sintered body, it is not added from the outside of the molded body before firing, but a part of the stabilizer contained in the raw material is fired during firing. It is preferable to move in the firing surface direction.

  In the following description, what is simply referred to as “zirconia” shall mean partially stabilized zirconia.

  The crystal form of the zirconia crystal particles in the zirconia sintered body of the present invention is mainly tetragonal. In the zirconia sintered body of the present invention, it is preferable that the monoclinic crystal is not substantially detected in the X-ray diffraction pattern in the untreated state at the low temperature deterioration acceleration test (hydrothermal test). Even if monoclinic crystals are contained in the zirconia sintered body of the present invention (untreated hydrothermal test state), in the X-ray diffraction pattern, a [111] peak derived from a tetragonal crystal with 2θ of around 30 ° is generated. The ratio of the height of the peak existing near the position where the [11-1] peak derived from the monoclinic crystal whose 2θ is around 28 ° to the height of the existing peak (ie, “monoclinic when 2θ is around 28 °) The height of the peak existing near the position where the [11-1] peak derived from the crystal occurs / the height of the peak existing near the position where the [111] peak derived from the tetragonal crystal with 2θ of around 30 ° occurs. Is; hereinafter referred to as “monoclinic peak ratio”) is preferably 0.2 or less, more preferably 0 to 0.1.

  The fired surface (or the vicinity thereof) of the zirconia sintered body of the present invention contains more cubic crystals than the inside of the zirconia sintered body. For example, when an X-ray diffraction pattern on the fired surface is measured, cubic crystals are observed, but when an X-ray diffraction pattern is measured on a surface obtained by grinding the fired surface to a depth of at least 100 μm, substantially no cubic crystals are observed.

  When the X-ray diffraction pattern was measured on the fired surface of the zirconia sintered body of the present invention and the height of the peak derived from the tetragonal crystal was compared with the height of the peak derived from the cubic crystal, 2θ was a square around 35.3 °. Ratio of the height of the peak existing near the position where the [200] peak derived from a cubic crystal having a 2θ of around 35.2 ° to the height of the peak existing near the position where the [200] peak derived from the crystal occurs ( That is, “the height of a peak existing near a position where a [11-1] peak derived from a cubic crystal with 2θ of around 35.2 ° occurs” / “[200] derived from a tetragonal crystal with 2θ of around 35.3 °”. The height of the peak near the position where the peak occurs; hereinafter referred to as “cubic peak ratio”) is 0.4 or more, preferably 1 or more, more preferably 2 or more, more preferably 3 or more, More preferably 5 or more The

  The region having a depth of 100 μm or more from the fired surface of the zirconia sintered body of the present invention contains a large amount of tetragonal crystals, and is preferably substantially tetragonal. When the sintered surface of the zirconia sintered body of the present invention is ground at a depth of 100 μm or more, the X-ray diffraction pattern is measured on the exposed surface, and the peak height derived from the tetragonal crystal is compared with the peak height derived from the cubic crystal, The peak ratio of the cubic crystal is preferably 0.3 or less, more preferably 0.1 or less, more preferably 0.05 or less, and it is preferable that substantially no cubic crystal is detected. It is because it is thought that bending strength and fracture toughness will fall when many cubic crystals are contained in a sintered compact. The “grinding” in the present invention includes polishing.

  It can be confirmed using a thin film X-ray diffraction method that many cubic crystals are contained in the vicinity of the fired surface of the zirconia sintered body of the present invention. In the region from the fired surface to a depth of about 8 μm (region where the incident angle of X-ray is 0 ° to 11 °), the peak height derived from the tetragonal crystal is compared with the peak height derived from the cubic crystal. Near the position at which a [311] peak derived from a cubic crystal with 2θ of about 70.5 ° occurs relative to the height of the peak existing near the position at which a [211] peak derived from a tetragonal crystal with 2θ of about 71.0 ° is generated. The ratio of the heights of the existing peaks (ie, “the height of the peak existing near the position where the [311] peak derived from the cubic where 2θ is around 70.5 ° occurs” / “2θ is around 71.0 ° The height of the peak existing near the position where the [211] peak derived from the tetragonal crystal occurs ”; hereinafter referred to as“ peak ratio of the fired surface layer ”is preferably 1 or more, more preferably 2 or more. More preferably, it is 3 or more. More preferably, it is above.

  Even if the zirconia sintered body of the present invention grinds the sintered surface (exposed surface after sintering) or the surface of the zirconia sintered body to expose a surface whose main crystal system is a tetragonal crystal, the zirconia sintered body When the body (sintered body with the ground surface exposed) is refired, it is more cubic than after regrinding before grinding without applying other treatments such as the application of a stabilizer in the same way as during sintering. It was found that crystals were formed near the refired surface. This is a surprising and unexpected event. For example, the fired surface or the exposed surface of the zirconia sintered body of the present invention is ground, and the X-ray diffraction pattern is derived from a cubic crystal with respect to the height of the peak existing near the position where the [200] peak derived from the tetragonal crystal is generated. 200] When a surface having a peak height ratio near the position where the peak occurs is 0.3 or less, more preferably 0.1 or less, and even more preferably 0.05 or less is exposed and refired, In the X-ray diffraction pattern on the fired surface, the ratio of the height of the peak existing near the position where the cubic [200] peak occurs to the height of the peak existing near the position where the tetragonal [200] peak occurs Is 0.4 or more, preferably 1 or more, more preferably 2 or more, still more preferably 3 or more, and still more preferably 5 or more.

  In the interior after refiring, the main crystal system is tetragonal. That is, in the X-ray diffraction pattern in the region where the depth from the refired surface is 100 μm or more, there is a [200] peak derived from a cubic crystal with respect to the height of the peak existing near the position where the [200] peak derived from a tetragonal crystal occurs. The ratio of the heights of the peaks existing in the vicinity of the generated position is 0.3 or less, more preferably 0.1 or less, and still more preferably 0.05 or less.

  The refiring temperature is preferably the same as the sintering temperature, and is preferably 1350 ° C. or higher and 1500 ° C. or lower. Note that “re-firing” in the present invention includes HIP treatment.

  According to the zirconia sintered body of the present invention, the sintered body is cut or ground into a desired shape, and even if a surface mainly composed of tetragonal crystals is exposed, the surface layer is obtained by re-firing. A product in which the cubic crystal is contained and the progress of hydrothermal deterioration is suppressed can be obtained.

The zirconia sintered body of the present invention contains boron (B). The content of boron (element) in the zirconia sintered body is preferably 3 × 10 ⁻⁴ mass% or more with respect to the mass of the zirconia sintered body, and more preferably 3 × 10 ⁻² mass% or more. preferable. Moreover, it is preferable that the content rate of boron (element) is 0.3 mass% or less with respect to the total mass of a zirconia sintered compact. By containing boron, it is possible to suppress the progress of the phase transition while lowering the sintering temperature.

  The zirconia sintered body according to the first embodiment of the present invention contains bismuth (Bi). The content of bismuth (element) in the zirconia sintered body is preferably 0.001% by mass or more, more preferably 0.05% by mass or more, based on the mass of the zirconia sintered body, More preferably, it is at least mass%. The content of bismuth (element) is preferably 1% by mass or less with respect to the total mass of the zirconia sintered body.

  In particular, when the content of boron (element) in the zirconia sintered body is 0.001% by mass or more with respect to the mass of the zirconia sintered body, the content of bismuth (element) in the zirconia sintered body is: It is preferable that it is 0.05 mass% or more with respect to the mass of a zirconia sintered compact. When the content of boron (element) in the zirconia sintered body is 0.05% by mass or more with respect to the mass of the zirconia sintered body, the content of bismuth (element) in the zirconia sintered body is It is preferable that it is 0.001 mass% or more with respect to the mass of a bonded body.

  In the zirconia sintered body according to the first embodiment of the present invention, a layer containing a cubic system can be formed on the fired surface of the zirconia sintered body by adding boron and bismuth in combination. Thereby, it can be set as the zirconia sintered compact which has high hydrothermal deterioration resistance.

  The zirconia sintered body of the present invention may further contain a phosphorus (P) element. In this case, the phosphorus content in the zirconia sintered body of the present invention is preferably 0.001% by mass or more with respect to the mass of the zirconia sintered body from the viewpoint of the effect of suppressing the phase transition, and 0.05 mass. % Or more, more preferably 0.1% by mass or more. The phosphorus content in the zirconia sintered body of the present invention is preferably 1% by mass or less, more preferably 0.6% by mass or less, based on the mass of the zirconia sintered body, More preferably, it is at most mass%.

  The zirconia sintered body of the present invention preferably contains aluminum oxide (preferably α-alumina). When aluminum oxide is contained, firing can be promoted as a sintering aid, and progress of low-temperature deterioration can be suppressed. The content of aluminum oxide in the zirconia sintered body of the present invention is preferably 0% by mass or more, more preferably 0.2% by mass or more, and more preferably 4% by mass or more with respect to the mass of the zirconia sintered body. Is more preferable. The content of aluminum oxide in the zirconia sintered body of the present invention is preferably 25% by mass or less, more preferably 20% by mass or less, and more preferably 10% by mass or less with respect to the mass of the zirconia sintered body. And more preferred. Moreover, the zirconia sintered body of the present invention can suppress the low temperature deterioration without containing aluminum oxide.

  At least a part of the aluminum oxide (preferably α-alumina) present in the zirconia sintered body of the present invention is preferably a columnar crystal or a needle crystal (whisker) (hereinafter referred to as “columnar crystal”). . The columnar crystal can be produced, for example, by firing at 1375 ° C. to 1500 ° C. in the presence of boron. The presence of the columnar crystal can be confirmed by, for example, a scanning electron microscope. When observed two-dimensionally with an electron microscope, the length of the columnar crystal appears to be 1 μm to 5 μm, for example. Whether the columnar crystal is α-alumina can be identified by an X-ray diffraction pattern.

  The aspect ratio of the columnar crystal is 2 or more, preferably 5 or more, more preferably 10 or more. This columnar crystal is an aluminum oxide crystal having an aspect ratio of about 1 (less than 2 and spherical in appearance) present in the composition for sintering a zirconia sintered body when the zirconia particles are sintered (preferably sintered). It is considered that the crystal has grown in a columnar shape or a needle shape at a temperature of 1375 ° C to 1500 ° C. When aluminum oxide becomes columnar crystals, it functions like a reinforcing fiber, and the strength and fracture toughness of the zirconia sintered body can be increased. In particular, when the sintering temperature is 1375 ° C. to 1450 ° C., the aspect ratio of the aluminum oxide crystal can be further increased. Depending on the blending of the additive, the aluminum oxide crystals may be spherical, but even if they become spherical, the strength and fracture toughness of the zirconia sintered body are not reduced.

  Since the change in the crystal form of aluminum oxide during sintering is not observed when no boron is added, it is considered that the change is caused by the addition of boron. Normally, columnar or needle crystals of aluminum oxide are not commercially available, and columnar crystals cannot be added as a raw material. Even if columnar crystals can be obtained, since the zirconia crystal particles are spherical, even if zirconia particles (spherical) and aluminum oxide particles (columnar) are mixed at the time of preparing the mixture, they cannot be mixed uniformly. It is difficult to produce a sintered body in which columnar aluminum oxide particles are uniformly dispersed. However, according to the present invention, spherical aluminum oxide can be easily changed to columnar aluminum oxide during sintering by adding boron to the composition.

The zirconia sintered body may contain an inorganic composite (eg, spinel, mullite) containing an Al ₂ O ₃ component in addition to or in place of aluminum oxide. By containing this inorganic composite, the wear resistance and the thermal stability can be improved.

  The zirconia sintered body of the present invention preferably further contains silicon dioxide. When the phosphorus element and silicon dioxide are contained in the zirconia sintered body, the effect of suppressing the phase transition can be further enhanced as compared with the case where only the phosphorus element is contained. The content of silicon dioxide in the zirconia sintered body of the present invention is preferably 0.03% by mass or more, and 0.05% by mass or more with respect to the mass of the zirconia sintered body, from the viewpoint of the effect of suppressing the phase transition. More preferably, it is more preferably 0.1% by mass or more. The content of silicon dioxide in the zirconia sintered body of the present invention is preferably 3% by mass or less and more preferably 1% by mass or less with respect to the mass of the zirconia sintered body from the viewpoint of the effect of suppressing the phase transition. Preferably, it is further more preferable in it being 0.8 mass% or less.

  According to SIMS, in the vicinity of the fired surface, particularly in a region where the content of cubic crystals is high (region where the content of the stabilizer is high), the content of silicon dioxide is lower than in the sintered body. . For example, it is considered that the content of silicon dioxide is low in the region from the fired surface to a depth of 4 μm and tends to increase at least in the region of 4 μm to 6 μm in depth from the fired surface.

  As described above, the zirconia sintered body of the present invention has a higher content of stabilizer and a higher abundance ratio of cubic crystals on the fired surface, as described above, by firing when the raw material powder is sintered. . In the zirconia sintered body of the present invention, the layer containing a large amount of cubic crystals (the layer containing a high content of the stabilizer) was removed by grinding the fired surface to expose the layer containing a large amount of tetragonal crystals. Even if it is refired later, on the refired surface, the content of the stabilizer can be increased and the abundance ratio of cubic crystals can be increased as described above. Therefore, in this invention, the zirconia sintered compact which reduced the speed | rate of the hydrothermal deterioration can be obtained by processing again a zirconia sintered compact after making it into a desired shape. That is, it is possible to obtain a zirconia sintered body having both precise processing dimensional accuracy.

  In the zirconia sintered body of the present invention, it is considered that the stabilizer moves to the fired surface by firing due to the effects of bismuth and the like and boron. This effect can be obtained even when only boron is added or only bismuth or the like is added. However, when both boron and bismuth are added, the effect becomes higher and a synergistic effect is obtained.

  The preferred zirconia sintered body of the present invention can suppress the phase transition from tetragonal to monoclinic even when subjected to a hydrothermal treatment test (low temperature degradation acceleration test) which is an accelerated test of low temperature degradation. In particular, the effect of suppressing the phase transition is remarkable for the sintered body fired at 1450 ° C. or higher. For example, when hydrothermal treatment at 180 ° C. and 1 MPa for 5 hours is performed on the zirconia sintered body of the present invention, the monoclinic peak ratio in the X-ray diffraction pattern on the surface of the zirconia sintered body after hydrothermal treatment is: Preferably it is 1 or less, More preferably, it is 0.5 or less, More preferably, it is 0.1 or less, More preferably, it is 0.05 or less, More preferably, it is 0.01 or less.

  In addition, when hydrothermal treatment was performed at 180 ° C. and 1 MPa for 24 hours on the zirconia sintered body of the present invention, the monoclinic peak in the X-ray diffraction pattern on the surface of the zirconia sintered body after hydrothermal treatment was obtained. The ratio is preferably 3 or less, more preferably 2 or less, still more preferably 1.5 or less, still more preferably 1 or less, and further preferably 0.5 or less.

  The preferred zirconia sintered body of the present invention has a small dimensional change even when subjected to a hydrothermal treatment test, and can maintain high dimensional accuracy. When the zirconia sintered body of the present invention is subjected to hydrothermal treatment at 180 ° C. and 1 MPa for 24 hours, the coefficient of expansion of the width of the test piece of the zirconia sintered body after hydrothermal treatment produced according to JIS R1601 Is preferably 0.6% or less, more preferably 0.5% or less, still more preferably 0.3% or less, and further preferably 0% or less with respect to the width of the test piece subjected to non-hydrothermal treatment. .1% or less, and more preferably 0.05% or less.

  The effects and advantages of adding boron element, phosphorus element and silicon dioxide are also described in the claims, specifications and drawings of Japanese Patent Application Nos. 2009-192287 and 2010-185586, which are incorporated herein by reference. Therefore, further explanation in this document is omitted.

  The stabilizer may be present non-uniformly as a whole in the zirconia sintered body. The fracture toughness value can be increased by unevenly distributing the stabilizer. The preferred degree of heterogeneity of the stabilizer can be represented, for example, by the standard deviation of the stabilizer concentration. When the concentration of the stabilizer on the sample surface of the zirconia sintered body is expressed in mass%, for example, the standard deviation of the stabilizer concentration in a portion of a total of 50,000 points or more is 0.8 or more, more preferably 1 As described above, more preferably 1.5 or more. The standard deviation of the stabilizer concentration is preferably 2 or less. When the standard deviation of the stabilizer concentration is 0.8 or more, the fracture toughness value of the zirconia sintered body can be increased. If the standard deviation of the stabilizer concentration is greater than 2, the instability becomes too high.

  The standard deviation is preferably calculated from the concentration of 50,000 points or more in the region of 10 μm × 10 μm of the sample surface of the zirconia sintered body. For example, as a method for measuring the standard deviation of the stabilizer concentration, for example, on the sample surface of the zirconia sintered body, a square region of 10 μm × 10 μm is divided into a grid of 256 cells in the vertical direction and 256 cells in the horizontal direction. The concentration of the stabilizer in the mass (total 65536 mass) is measured, and the standard deviation is obtained.

  As a method for measuring the concentration of the stabilizer on the sample surface of the zirconia sintered body, for example, a stabilizer on the sample surface using a field emission electron probe microanalyzer (FE-EPMA) or the like is used. Concentration can be measured. A method of collecting a part of the zirconia sintered body and measuring the concentration without depending on the sample surface concentration may be used.

  The matters relating to the stabilizer concentration, standard deviation, measurement method, and the like in the zirconia sintered body are the same even in the case of the calcined body of the zirconia sintered body, and the description thereof is omitted here.

  The effect of suppressing the phase transition in the zirconia sintered body of the present invention is not affected by the particle size in the zirconia sintered body. Therefore, a suitable particle size can be selected appropriately according to the application.

  The zirconia sintered body of the present invention preferably has translucency and is not colored. Thereby, the external appearance of the zirconia sintered compact can be adjusted according to a use by adding a pigment etc. to this invention. For example, the zirconia sintered body of the present invention can be suitably used as a dental material such as a prosthetic material. Moreover, it is preferable that the zirconia sintered body does not have a matte feeling and has an appearance that does not look unsintered.

  In the zirconia sintered body of the present invention, the average particle diameter of the primary particles of the zirconia crystal particles in the inside thereof can be 0.1 μm to 5 μm. The average particle size of the primary particles was calculated as the average value of the major axis and the minor axis of 100 primary particles randomly extracted from a scanning electron microscope (SEM) photograph. Further, in the region from the fired surface to a depth of 5 μm, as seen from the SEM photograph, the outline of the zirconia crystal particles is not clear and is in a molten state. Note that, in the entire disclosure of the present invention, each numerical range includes any intermediate value belonging to the middle even when not specified, and the display of the intermediate value is omitted for convenience of description.

  Next, a zirconia sintered body according to the second embodiment of the present invention will be described.

  The zirconia according to the first embodiment of the present invention contains bismuth, but the zirconia sintered body according to the second embodiment of the present invention contains tin (Sn) instead of bismuth. The forms other than containing tin are the same as those in the first embodiment. The content of tin (element) in the zirconia sintered body is preferably 0.001% by mass or more, more preferably 0.05% by mass or more with respect to the mass of the zirconia sintered body, More preferably, it is at least mass%. The content of tin (element) is preferably 1% by mass or less with respect to the mass of the zirconia sintered body.

  In particular, when the content of boron (element) in the zirconia sintered body is 0.001% by mass or more with respect to the mass of the zirconia sintered body, the content of tin (element) in the zirconia sintered body is: It is preferable that it is 0.05 mass% or more with respect to the mass of a zirconia sintered compact. When the content of boron (element) in the zirconia sintered body is 0.05% by mass or more with respect to the mass of the zirconia sintered body, the content of tin (element) in the zirconia sintered body is It is preferable that it is 0.001 mass% or more with respect to the mass of a bonded body.

  In the zirconia sintered body according to the second embodiment of the present invention, a layer containing a cubic system can be formed on the fired surface of the zirconia sintered body by adding boron and tin in combination. Thereby, it can be set as the zirconia sintered compact which has high hydrothermal deterioration resistance.

  Next, a zirconia sintered body according to the third embodiment of the present invention will be described.

  The zirconia according to the first embodiment of the present invention contains bismuth, but the zirconia sintered body according to the third embodiment of the present invention contains germanium (Ge) instead of bismuth. Forms other than the germanium content are the same as in the first embodiment. The content of germanium (element) in the zirconia sintered body is preferably 0.001% by mass or more, more preferably 0.1% by mass or more with respect to the mass of the zirconia sintered body, and 0.2 More preferably, it is at least mass%. The content of germanium (element) is preferably 1% by mass or less with respect to the mass of the zirconia sintered body.

  In particular, when the content of boron (element) in the zirconia sintered body is 0.001% by mass or more with respect to the mass of the zirconia sintered body, the content of germanium (element) in the zirconia sintered body is: It is preferable that it is 0.2 mass% or more with respect to the mass of a zirconia sintered compact. When the content of boron (element) in the zirconia sintered body is 0.05% by mass or more with respect to the mass of the zirconia sintered body, the content of germanium (element) in the zirconia sintered body is It is preferable that it is 0.001 mass% or more with respect to the mass of a bonded body.

  In the zirconia sintered body according to the third embodiment of the present invention, a layer containing a cubic system can be formed on the fired surface of the zirconia sintered body by adding boron and germanium in combination. Thereby, it can be set as the zirconia sintered compact which has high hydrothermal deterioration resistance.

  Next, a zirconia sintered body according to the fourth embodiment of the present invention will be described.

  The zirconia according to the first embodiment of the present invention contains bismuth, but the zirconia sintered body according to the fourth embodiment of the present invention contains sulfur (S) instead of bismuth. The forms other than the sulfur content are the same as in the first embodiment. The content of sulfur (element) in the zirconia sintered body is preferably 0.001% by mass or more with respect to the mass of the zirconia sintered body. The content of sulfur (element) is preferably 1% by mass or less, more preferably 0.2% by mass or less, and further preferably 0.1% by mass or less with respect to the mass of the zirconia sintered body. .

  In particular, when the content of boron (element) in the zirconia sintered body is 0.001% by mass or more with respect to the mass of the zirconia sintered body, the content of sulfur (element) in the zirconia sintered body is: It is preferable that it is 0.1 mass% or more with respect to the mass of a zirconia sintered compact. When the content of boron (element) in the zirconia sintered body is 0.05% by mass or more with respect to the mass of the zirconia sintered body, the content of sulfur (element) in the zirconia sintered body is It is preferable that it is 0.001 mass% or more with respect to the mass of a bonded body.

  In the zirconia sintered body according to the fourth embodiment of the present invention, a layer containing a cubic system can be formed on the fired surface of the zirconia sintered body by adding boron and sulfur in combination. Thereby, it can be set as the zirconia sintered compact which has high hydrothermal deterioration resistance.

  Next, a zirconia sintered body according to the fifth embodiment of the present invention will be described.

  In 1st-4th embodiment, although the zirconia sintered compact which contains bismuth, tin, germanium, and sulfur alternatively was demonstrated, the zirconia sintered compact which concerns on 5th Embodiment of this invention is bismuth, Contains two or more elements of tin, germanium and sulfur. Other aspects are the same as described above, and the description thereof is omitted here.

  Each content rate of boron, bismuth, tin, germanium, sulfur, phosphorus, aluminum oxide, and silicon dioxide in the zirconia sintered body according to the first to fifth embodiments can be measured by composition analysis of the zirconia sintered body. it can. Each content of boron, bismuth, tin, germanium, sulfur, phosphorus, aluminum oxide, and silicon dioxide in the zirconia sintered body can be measured by, for example, inductively coupled plasma (ICP) emission spectroscopy. . In addition, each addition rate of boron, bismuth, tin, germanium, sulfur, phosphorus, aluminum oxide, and silicon dioxide (that is, each content before firing) added during the preparation of the zirconia sintered composition, and zirconia firing If the contents of boron, bismuth, tin, germanium, sulfur, phosphorus, aluminum oxide and silicon dioxide (ie, the content after firing) in the aggregate can be substantially equated, partially stabilized zirconia and oxidation You may consider each addition rate with respect to the total mass of aluminum as each content rate of boron, bismuth, tin, germanium, sulfur, phosphorus, aluminum oxide, and silicon dioxide in a zirconia sintered compact.

  Boron, bismuth, tin, germanium, sulfur, phosphorus, aluminum oxide and silicon dioxide may be included in the zirconia crystal particles or may exist in the crystal grain boundaries. That is, boron, bismuth, tin, germanium, sulfur, phosphorus, aluminum oxide, and silicon dioxide may be added at the time of preparing zirconia crystal particles, or zirconia crystal particles and boron may be mixed and formed into a predetermined shape. Good.

  Next, the sintering composition and calcined body of the zirconia sintered body of the present invention will be described. The composition for sinter of a zirconia sintered body and a calcined body serve as a precursor (intermediate product) of the zirconia sintered body of the present invention. That is, the zirconia sintered body composition and calcined body of the present invention can obtain a zirconia sintered body having at least one of the above properties. The composition for sintering includes a powder, a fluid obtained by adding the powder to a solvent, and a molded body obtained by molding the powder into a predetermined shape.

  In addition, about the zirconia sintered compact which concerns on 1st-5th embodiment, the composition for sintering for manufacturing the zirconia sintered compact which concerns on each embodiment, and a calcined body are the same forms except a different component Therefore, the following will be described collectively.

  The composition for sintering a zirconia sintered body according to the first embodiment contains partially stabilized zirconia crystal particles, a bismuth simple substance or a bismuth-containing compound, and a boron-containing compound. Similarly, in the case of the second embodiment, the zirconia sintered body composition contains tin alone or a tin-containing compound, and in the case of the third embodiment, contains a germanium simple substance or a germanium-containing compound. In the case of the embodiment, it contains sulfur alone or a sulfur-containing compound.

  Examples of the stabilizer in the partially stabilized zirconia crystal particles include oxides of oxides such as calcium oxide, magnesium oxide, yttrium oxide, and cerium oxide. The stabilizer is preferably added in such an amount that the zirconia particles can be partially stabilized. For example, when yttrium oxide is used as a stabilizer, the content of yttrium oxide is preferably 2 mol% to 5 mol% (about 3 mass% to 9 mass%) with respect to the partially stabilized zirconium oxide. . The content of the stabilizer in the zirconia sintered body can be measured, for example, by inductively coupled plasma (ICP) emission spectroscopy.

  In the composition for sintering (unfired product), for example, the stabilizer is not present at a higher concentration on the outer surface (exposed surface) than in the molded body. The content of the stabilizer is the same in the portion that becomes the outer surface (fired surface) of the sintered body and the portion that becomes the inside of the sintered body.

The boron-containing compound may be contained in the zirconia crystal particles or may exist between the zirconia crystal particles. The content of boron (element) in the sintering composition is preferably 4 × 10 ⁻⁵ mol or more, more preferably 8 × 10 ⁻³ mol or more with respect to 1 mol of zirconium oxide. Further, the content of boron (element) is preferably at least 4 × 10 ⁻² mol or less with respect to 1 mol of zirconium oxide.

Examples of the boron-containing compound include boron oxide (B ₂ O ₃ ), boron nitride (BN), boron carbide (B ₄ C), boric acid (H ₃ BO ₃ , HBO ₂ , H ₂ B ₄ O ₇ ), In the present invention, elements that can be added as stabilizers and additives (for example, Zr, Al, Si, Y, P, Bi, Sn, Ge, S, etc.) and boron compounds can be used.

When the bismuth simple substance or the bismuth-containing compound is contained, the bismuth simple substance or the bismuth-containing compound may be contained in the zirconia crystal particles or may exist between the zirconia crystal particles. The zirconia crystal particles may be granulated. The content of bismuth in the sintering composition is preferably 6 × 10 ⁻⁶ mol or more and more preferably 3 × 10 ⁻⁴ mol or more with respect to 1 mol of zirconium oxide from the viewpoint of the effect of suppressing the phase transition. Preferably, it is more preferably 6 × 10 ⁻⁴ mol or more. Further, the content of bismuth in the sintering composition is preferably 7 × 10 ⁻³ mol or less with respect to 1 mol of zirconium oxide. When two or more bismuth is contained in one molecule of the bismuth-containing compound, the bismuth content is calculated based on the number of bismuth atoms, not the number of molecules of the bismuth-containing compound.

In particular, the content of boron (element) in the sintering composition, when it is 4 × ¹⁰ -5 mol or more relative to the zirconium oxide 1 mol, the content of bismuth, 3 × 10 relative to zirconium oxide 1 mol ^- It is preferable that it is ⁴ mol or more. When the boron (element) content in the sintering composition is 2 × 10 ⁻³ mol or more with respect to 1 mol of zirconium oxide, the content of bismuth is 6 × 10 ⁻⁶ mol with respect to 1 mol of zirconium oxide. The above is preferable.

Examples of the bismuth-containing compound include bismuth oxide (Bi ₂ O ₃ ), bismuth acetate (BiC ₆ H ₉ O ₆ ), basic bismuth carbonate ((BiO) ₂ CO ₃ ), and bismuth carbonate oxide (Bi ₂ (CO _3). ) O ₂ ), bismuth chloride (BiCl ₃ ), bismuth nitrate nitrate (4BiNO ₃ (OH) ₂ .BiO (OH)), bismuth nitrate pentahydrate (Bi (NO ₃ ) ₃ .5H ₂ O), phosphorus Bismuth acid (BiPO ₄ ), bismuth sulfate (Bi ₂ (SO ₄ ) ₃ ), bismuth sulfide (Bi ₂ S ₃ ), and the like can be used.

When containing a tin simple substance or a tin-containing compound, the tin simple substance or the tin-containing compound may be contained in the zirconia crystal particles, or may be present between the zirconia crystal particles. The zirconia crystal particles may be granulated. The content of tin in the sintering composition is preferably 1 × 10 ⁻⁵ mol or more with respect to 1 mol of zirconium oxide, and more preferably 5 × 10 ⁻⁴ mol or more, from the viewpoint of the effect of suppressing the phase transition. Preferably, it is more preferably 1 × 10 ⁻³ mol or more. Further, the content of tin in the composition for sintering is preferably 2 × 10 ⁻² mol or less with respect to 1 mol of zirconium oxide. When two or more tins are contained in one molecule of the tin-containing compound, the tin content is calculated based on the number of tin atoms, not the number of molecules of the tin-containing compound.

In particular, the content of boron (element) in the sintering composition, when it is 4 × ¹⁰ -5 mol or more relative to the zirconium oxide 1 mol, the content of tin, 5 × 10 relative to zirconium oxide 1 mol ^- It is preferable that it is ⁴ mol or more. When the content of boron (element) in the sintering composition is 2 × 10 ⁻³ mol or more with respect to 1 mol of zirconium oxide, the content of tin is 1 × 10 ⁻⁵ mol with respect to 1 mol of zirconium oxide. The above is preferable.

Examples of the tin-containing compound include tin oxide (SnO, SnO ₂ ), tin chloride (SnCl ₂ ), tin diphosphate (Sn ₂ P ₂ O ₇ ), tin phosphide (P ₂ Sn ₃ ), tin sulfate ( SnSO ₄ ) or the like can be used.

When containing a germanium simple substance or a germanium-containing compound, the germanium simple substance or the germanium-containing compound may be contained in the zirconia crystal particles, or may be present between the zirconia crystal particles. The zirconia crystal particles may be granulated. The germanium content in the sintering composition is preferably 1 × 10 ⁻⁵ mol or more, and more preferably 1 × 10 ⁻³ mol or more with respect to 1 mol of zirconium oxide, from the viewpoint of the effect of suppressing the phase transition. Preferably, it is more preferably 3 × 10 ⁻³ mol or more. Further, the germanium content in the sintering composition is preferably 2 × 10 ⁻² mol or less with respect to 1 mol of zirconium oxide. In addition, when two or more germanium is contained in one molecule of the germanium-containing compound, the germanium content is calculated based on the number of germanium atoms, not the number of molecules of the germanium-containing compound.

In particular, the content of boron (element) in the sintering composition, when it is 4 × ¹⁰ -5 mol or more relative to the zirconium oxide 1 mol, the content of germanium, 3 × 10 relative to zirconium oxide 1 mol ^- It is preferable that it is ³ mol or more. When the boron (element) content in the sintering composition is 2 × 10 ⁻³ mol or more with respect to 1 mol of zirconium oxide, the germanium content is 1 × 10 ⁻⁵ mol with respect to 1 mol of zirconium oxide. The above is preferable.

As the germanium-containing compound, for example, germanium oxide (GeO, GeO ₂ ), germanium chloride (GeCl ₄ ), germanium sulfide (GeS), or the like can be used.

When containing a sulfur simple substance or a sulfur-containing compound, the sulfur simple substance or the sulfur-containing compound may be contained in the zirconia crystal particles, or may be present between the zirconia crystal particles. The zirconia crystal particles may be granulated. The sulfur content in the composition for sintering is preferably 4 × 10 ⁻⁵ mol or more with respect to 1 mol of zirconium oxide from the viewpoint of the effect of suppressing the phase transition. The content of sulfur in the sintering compositions for zirconium oxide 1 mol, preferably is not more than 5 × ¹⁰ -2 mol, more preferably is not more than ^{9 × 10 -3 mol, 5 ×} 10 - More preferably, it is ³ mol or less. In addition, when 2 or more sulfur is contained in 1 molecule of sulfur-containing compounds, the sulfur content is calculated based on the number of sulfur atoms, not the number of molecules of the sulfur-containing compound.

In particular, the content of boron (element) in the sintering composition, when it is 4 × ¹⁰ -5 mol or more relative to the zirconium oxide 1 mol, the content of sulfur is 4 with respect to the zirconium oxide 1 mol × 10 ^- It is preferable that it is ³ mol or more. When the boron (element) content in the sintering composition is 2 × 10 ⁻³ mol or more with respect to 1 mol of zirconium oxide, the sulfur content is 4 × 10 ⁻⁵ mol with respect to 1 mol of zirconium oxide. The above is preferable.

As the sulfur-containing compound, for example, sulfuric acid (H ₂ SO ₄ ), ammonium sulfate ((NH ₄ ) ₂ SO ₄ ), aluminum sulfate (Al ₂ (SO ₄ ) ₃ ), or the like can be used.

The composition for sintering of the present invention preferably further contains aluminum oxide (preferably α-alumina). Aluminum oxide may be contained in the zirconia crystal particles or may exist between the zirconia crystal particles. The content of aluminum oxide in the sintering composition is preferably 2 × 10 ⁻³ mol or more, and more preferably 5 × 10 ⁻² mol or more with respect to 1 mol of zirconium oxide. The content of aluminum oxide in the sintering composition is preferably 0.5 mol or less, more preferably 0.3 mol or less, and more preferably 0.2 mol or less with respect to 1 mol of zirconium oxide. .

  The aspect ratio of aluminum oxide present in the sintering composition is less than 2 in two-dimensional observation. At least a portion of the aluminum oxide present in the sintering composition becomes columnar or needle-like (for example, an aspect ratio of 5 or more, more preferably 10 or more) when the partially stabilized zirconia is sintered.

The composition for sintering may contain an inorganic composite (eg, spinel, mullite) containing an Al ₂ O ₃ component in addition to or in place of aluminum oxide.

The sintering composition of the present invention preferably further contains silicon dioxide. Silicon dioxide may be contained in the zirconia crystal particles or may exist between the zirconia crystal particles. When the phosphorous element and silicon dioxide are contained in the sintering composition, the effect of suppressing the phase transition against low temperature deterioration of the zirconia sintered body can be further enhanced as compared with the case where only the phosphorous element is contained. The content of silicon dioxide in the pre-molded sintered body of the present invention is preferably 7 × 10 ⁻⁴ mol or more with respect to 1 mol of zirconium oxide, from the viewpoint of the effect of suppressing the phase transition, and 1 × 10 ⁻³ mol or more. More preferably, it is more preferably 2 × 10 ⁻³ mol or more. The content of silicon dioxide in the pre-molded sintered body of the present invention is preferably 7 × 10 ⁻² mol or less with respect to 1 mol of zirconium oxide from the viewpoint of the effect of suppressing the phase transition, and 3 × 10 ⁻² mol or less. More preferably, it is more preferably 2 × 10 ⁻² mol or less.

The composition for sintering contains a substance (for example, (C ₂ H ₅ O) ₄ Si, Si ₃ N ₄ , Si) that becomes silicon dioxide by firing in addition to or in place of silicon dioxide. May be. The compositions for sintering may contain inorganic composite containing SiO ₂ component (e.g., mullite).

The composition for sintering may further contain phosphorus. The phosphorus element simple substance or the phosphorus element-containing compound may be contained in the zirconia crystal particles, or may exist between the zirconia crystal particles. The zirconia crystal particles may be granulated. The content of elemental phosphorus in the sintering composition, in terms of phase transition suppression effect for zirconium oxide 1 mol, when is ^{4 × 10 -4 mol~5 × 10 -2} mol Preferably, 4 × 10 ^- More preferably, it is ³ mol% by mass to 3 × 10 ⁻² mol, and further preferably 8 × 10 ⁻³ mol to ² × 10 ⁻² mol. When two or more phosphorus elements are contained in one molecule of the phosphorus element-containing compound, the phosphorus element content is calculated based on the number of atoms of the phosphorus element, not the number of molecules of the phosphorus element-containing compound.

Examples of the phosphorus-containing compound include phosphoric acid (H ₃ PO ₄ ), aluminum phosphate (AlPO ₄ ), magnesium phosphate (Mg ₃ (PO ₄ ) ₂ ), calcium phosphate (Ca ₃ (PO ₄ ) ₂ ), phosphorus Magnesium hydrogen oxyhydrogen (MgHPO ₄ ), magnesium dihydrogen phosphate (Mg (H ₂ PO ₄ ) ₂ ), calcium hydrogen phosphate (CaHPO ₄ ), ammonium dihydrogen phosphate ((NH ₄ ) H ₂ PO ₄ ), etc. Can be mentioned.

  The particle size of the zirconia crystal particles is not particularly limited, and a particle size suitable for obtaining a desired sintered body can be selected.

  The sintering composition may be in the form of a powder, or may be a paste or a wet composition (that is, it may be in a solvent or may contain a solvent). Moreover, the composition for sintering may contain additives, such as a binder.

  When the composition for sintering of the present invention is a molded body, it may be molded by any molding method, and may be molded by, for example, press molding, injection molding, or stereolithography. It may be one that has been formed in stages. For example, a CIP (Cold Isostatic Pressing) process may be performed after the sintering composition of the present invention is press-molded.

  The sintering composition of the present invention contains low-stabilized zirconia particles containing or not containing a stabilizer, and highly-stabilized zirconia particles containing more stabilizer than the low-stabilized zirconia particles. May be. That is, a plurality of zirconia particles having different stabilizer contents (or concentrations) may be mixed. The content of the stabilizer in the low-stabilized zirconia particles is preferably 0 mol% or more and less than 2 mol% with respect to the total number of moles of zirconium oxide and the stabilizer. The content of the stabilizer in the highly stabilized zirconia particles is preferably 2 mol% or more and less than 8 mol% with respect to the total number of moles of zirconium oxide and the stabilizer. The stabilizer content of the highly stabilized zirconia particles is preferably 0.5 mol% to 7 mol% higher than the stabilizer content of the low stabilized zirconia particles, more preferably 1 mol% to 7 mol% higher. More preferably, it is higher by 5 mol% to 7 mol%. For example, the stabilizer content of the low-stabilized zirconia particles can be 1 mol%, and the stabilizer content of the highly-stabilized zirconia particles can be 3 mol%. Regarding the mixing ratio of the low-stabilized zirconia particles and the highly-stabilized zirconia particles, the content of the low-stabilized zirconia particles is 5% by mass to 40% by mass with respect to the total mass of the low-stabilized zirconia particles and the high-stabilized zirconia particles. %, More preferably 10% by mass to 30% by mass, and even more preferably 15% by mass to 25% by mass. This provides a standard deviation in stabilizer concentration that can increase fracture toughness.

  In the present invention, “highly stabilized” and “lowly stabilized” and two types of zirconia particles are mixed, but three or more types of zirconia particles having different stabilizer contents may be mixed. . In this case, the standard deviation of the stabilizer concentration is adjusted by appropriately adjusting the stabilizer content and the mixing ratio of each zirconia particle.

  The sintering composition of the present invention becomes the zirconia sintered body of the present invention by firing at 1350 ° C to 1550 ° C. The aluminum oxide present in the sintering composition becomes columnar or needle-like crystals (preferably an aspect ratio of 2 or more, more preferably 5 or more, and even more preferably 10 or more) when the zirconia particles are sintered.

  The sintering composition of the present invention becomes a calcined body of the zirconia sintered body of the present invention by firing at 800 ° C. to 1200 ° C.

  The calcined body of the present invention is obtained by firing the sintering composition of the present invention at a temperature at which the zirconia particles do not sinter, or part or part of the zirconia particles of the sintering composition of the present invention. Sintered into The boron content, bismuth content, tin content, germanium content, sulfur content, phosphorus content, aluminum oxide content and silicon dioxide content in the calcined product of the present invention are the sintering composition of the present invention. This is the same as in the case of, and the explanation here is omitted.

  The calcined body of the present invention can be obtained by firing the sintering composition of the present invention at 800 ° C to 1200 ° C. On the sample surface of the calcined body, the stabilizer is preferably present in a non-uniform manner as a whole.

  The calcined body of the present invention becomes the zirconia sintered body of the present invention by firing at 1350 ° C. to 1600 ° C.

  Next, the zirconia sintered body of the present invention, the composition for sintering the zirconia sintered body, and the method for producing the calcined body will be described.

  In the following, as one embodiment, a manufacturing method in the case where the desired amount of boron or the like is not contained in the partially stabilized zirconia crystal particles will be described.

  First, partially stabilized zirconia crystal particles are prepared. The kind and concentration of the stabilizer can be appropriately selected. Moreover, in order to make the concentration distribution of the stabilizer non-uniform, highly stabilized zirconia crystal particles and low stabilized zirconia crystal particles may be used. As the particle size and particle size distribution of the zirconia crystal particles, suitable ones are appropriately selected.

As a method for adding the stabilizer to the zirconia crystal particles, a hydrolysis method, a neutralization coprecipitation method, an alkoxide method, a solid phase method, or the like can be used. For example, when a sintered body is produced using Y ₂ O ₃ solid solution ZrO ₂ obtained by a solid phase method, fracture toughness can be increased. In particular, when a zirconia sintered body to which phosphorus is added is produced using a solid phase method, a zirconia sintered body having higher fracture toughness can be obtained due to the synergistic effect.

  Second, zirconia crystal particles, a bismuth-containing compound or a bismuth simple substance, and a boron-containing compound are mixed to produce the sintering composition of the present invention.

The addition amount of boron (element) is preferably 4 × 10 ⁻⁵ mol or more, and more preferably 8 × 10 ⁻³ mol or more with respect to 1 mol of zirconium oxide. Further, the content of boron (element) is preferably at least 4 × 10 ⁻² mol or less with respect to 1 mol of zirconium oxide. When two or more boron elements are contained in one molecule of the boron element-containing compound, the calculation is performed based on the number of atoms of the boron element, not the number of molecules of the boron element-containing compound.

Examples of the boron-containing compound include boron oxide (B ₂ O ₃ ), boron nitride (BN), boron carbide (B ₄ C), boric acid (H ₃ BO ₃ , HBO ₂ , H ₂ B ₄ O ₇ ), In the present invention, elements that can be added as stabilizers and additives (for example, Zr, Al, Si, Y, P, Bi, Sn, Ge, S, etc.) and boron compounds can be used.

When adding bismuth, the addition amount of the bismuth element is preferably 6 × 10 ⁻⁶ mol or more, more preferably 3 × 10 ⁻⁴ mol or more, and 6 × 10 ⁻⁴ mol per 1 mol of zirconium oxide. More preferably, it is at least mol. . Moreover, it is preferable that the addition amount of a bismuth element is 7 * 10 < ^-3 > mol or less with respect to 1 mol of zirconium oxide. In particular, the content of boron (element) in the sintering composition, when it is 4 × ¹⁰ -5 mol or more relative to the zirconium oxide 1 mol, the content of bismuth, 3 × 10 relative to zirconium oxide 1 mol ^- It is preferable that it is ⁴ mol or more. When the boron (element) content in the sintering composition is 2 × 10 ⁻³ mol or more with respect to 1 mol of zirconium oxide, the content of bismuth is 6 × 10 ⁻⁶ mol with respect to 1 mol of zirconium oxide. The above is preferable. When two or more bismuth is contained in one molecule of the bismuth-containing compound, the calculation is based on the number of atoms of bismuth, not the number of molecules of the bismuth-containing compound.

Examples of the bismuth-containing compound include bismuth oxide (Bi ₂ O ₃ ), bismuth acetate (BiC ₆ H ₉ O ₆ ), basic bismuth carbonate ((BiO) ₂ CO ₃ ), and bismuth carbonate oxide (Bi ₂ (CO _3). ) O ₂ ), bismuth chloride (BiCl ₃ ), bismuth nitrate nitrate (4BiNO ₃ (OH) ₂ .BiO (OH)), bismuth nitrate pentahydrate (Bi (NO ₃ ) ₃ .5H ₂ O), phosphorus Bismuth acid (BiPO ₄ ), bismuth sulfate (Bi ₂ (SO ₄ ) ₃ ), bismuth sulfide (Bi ₂ S ₃ ), and the like can be used.

When adding tin, the addition amount of tin element is preferably 1 × 10 ⁻⁵ mol or more, more preferably 5 × 10 ⁻⁴ mol or more, with respect to 1 mol of zirconium oxide, and 1 × 10 ⁻³ mol. More preferably, it is at least mol. The amount of tin element added is preferably 2 × 10 ⁻² mol or less with respect to 1 mol of zirconium oxide. In particular, the content of boron (element) in the sintering composition, when it is 4 × ¹⁰ -5 mol or more relative to the zirconium oxide 1 mol, the content of tin, 5 × 10 relative to zirconium oxide 1 mol ^- It is preferable that it is ⁴ mol or more. When the content of boron (element) in the sintering composition is 2 × 10 ⁻³ mol or more with respect to 1 mol of zirconium oxide, the content of tin is 1 × 10 ⁻⁵ mol with respect to 1 mol of zirconium oxide. The above is preferable. When two or more tins are contained in one molecule of the tin-containing compound, the calculation is performed based on the number of tin atoms, not the number of molecules of the tin-containing compound.

Examples of the tin-containing compound include tin oxide (SnO, SnO ₂ ), tin chloride (SnCl ₂ ), tin diphosphate (Sn ₂ P ₂ O ₇ ), tin phosphide (P ₂ Sn ₃ ), tin sulfate ( SnSO ₄ ) or the like can be used.

When adding germanium, the addition amount of germanium element is preferably 1 × 10 ⁻⁵ mol or more, more preferably 1 × 10 ⁻³ mol or more, with respect to 1 mol of zirconium oxide, and 3 × 10 ^−3. More preferably, it is at least mol. Moreover, it is preferable that the addition amount of a germanium element is 2 * 10 ^<-2 > mol or less with respect to 1 mol of zirconium oxides. In particular, the content of boron (element) in the sintering composition, when it is 4 × ¹⁰ -5 mol or more relative to the zirconium oxide 1 mol, the content of germanium, 3 × 10 relative to zirconium oxide 1 mol ^- It is preferable that it is ³ mol or more. When the boron (element) content in the sintering composition is 2 × 10 ⁻³ mol or more with respect to 1 mol of zirconium oxide, the germanium content is 1 × 10 ⁻⁵ mol with respect to 1 mol of zirconium oxide. The above is preferable. When two or more germanium is contained in one molecule of the germanium-containing compound, the calculation is performed based on the number of germanium atoms, not the number of molecules of the germanium-containing compound.

As the germanium-containing compound, for example, germanium oxide (GeO, GeO ₂ ), germanium chloride (GeCl ₄ ), germanium sulfide (GeS), or the like can be used.

When sulfur is added, the amount of sulfur element added is preferably 4 × 10 ⁻⁵ mol or more with respect to 1 mol of zirconium oxide. Moreover, the addition amount of sulfur element is preferably 5 × 10 ⁻² mol or less, more preferably 9 × 10 ⁻³ mol or less, and more preferably 5 × 10 ⁻³ mol or less with respect to 1 mol of zirconium oxide. And more preferred. In particular, the content of boron (element) in the sintering composition, when it is 4 × ¹⁰ -5 mol or more relative to the zirconium oxide 1 mol, the content of sulfur is 4 with respect to the zirconium oxide 1 mol × 10 ^- It is preferable that it is ³ mol or more. When the boron (element) content in the sintering composition is 2 × 10 ⁻³ mol or more with respect to 1 mol of zirconium oxide, the sulfur content is 4 × 10 ⁻⁵ mol with respect to 1 mol of zirconium oxide. The above is preferable. When 2 or more sulfur is contained in one molecule of the sulfur-containing compound, the calculation is based on the number of sulfur atoms, not the number of molecules of the sulfur-containing compound.

As the sulfur-containing compound, for example, sulfuric acid (H ₂ SO ₄ ), ammonium sulfate ((NH ₄ ) ₂ SO ₄ ), aluminum sulfate (Al ₂ (SO ₄ ) ₃ ), or the like can be used.

  The bismuth-containing compound, tin-containing compound, germanium-containing compound, and sulfur-containing compound may be either an inorganic compound or an organic compound. When an inorganic compound is used, for example, bismuth oxide, tin oxide, germanium oxide, sulfuric acid, or the like can be used.

  When the zirconia sintered body of the present invention is used in a human body like a dental prosthetic material, the bismuth-containing compound, tin-containing compound, germanium-containing compound, and sulfur-containing compound have a small adverse effect on the human body. Preferably, it is more harmless to the human body.

It is preferable to add aluminum oxide (preferably α-alumina) to the sintering composition. The amount of aluminum oxide added is preferably 2 × 10 ⁻³ mol or more, and more preferably 5 × 10 ⁻² mol or more. The amount of aluminum oxide added is preferably 0.5 mol or less, more preferably 0.3 mol or less, and more preferably 0.2 mol or less with respect to 1 mol of zirconium oxide.

It is preferable to further add silicon dioxide to the sintering composition. The addition amount of silicon dioxide is preferably 7 × 10 ⁻⁴ mol or more, more preferably 1 × 10 ⁻³ mol or more, and further preferably 2 × 10 ⁻³ mol or more with respect to 1 mol of zirconium oxide. preferable. The addition amount of silicon dioxide is preferably 7 × 10 ⁻² mol or less, more preferably 3 × 10 ⁻² mol or less, and more preferably 2 × 10 ⁻² mol or less with respect to 1 mol of zirconium oxide. And more preferred. In addition to silicon dioxide or in place of silicon dioxide, a substance that becomes silicon dioxide upon firing (for example, (C ₂ H ₅ O) ₄ Si, Si ₃ N ₄ , Si) may be used. The inorganic composite containing SiO ₂ component (e.g., mullite) may be used.

You may add phosphorus further to the composition for sintering. The addition amount of the phosphorus element is preferably 4 × 10 ⁻⁵ mol or more, more preferably 4 × 10 ⁻³ mol% or more, and 9 × 10 ⁻³ mol or more with respect to 1 mol of zirconium oxide. Further preferred. Further, the amount of phosphorus added is preferably 5 × 10 ⁻² mol or less, more preferably 4 × 10 ⁻² mol or less, with respect to 1 mol of zirconium oxide, from the viewpoint of the effect of suppressing the phase transition, and more preferably 3 × 10 ⁻² mol or less. More preferably, it is 10 ⁻² mol or less. When two or more phosphorus elements are contained in one molecule of the phosphorus element-containing compound, the calculation is performed based on the number of atoms of the phosphorus element, not the number of molecules of the phosphorus element-containing compound.

The phosphorus element-containing compound may be either an inorganic compound or an organic compound. When an inorganic compound is used, for example, phosphoric acids and phosphates can be used. In this case, for example, phosphoric acid (H ₃ PO ₄ ), aluminum phosphate (AlPO ₄ ), magnesium phosphate (Mg ₃ (PO ₄ ) ₂ ), calcium phosphate (Ca ₃ (PO ₄ ) ₂ ), magnesium hydrogen phosphate (MgHPO ₄ ), magnesium dihydrogen phosphate (Mg (H ₂ PO ₄ ) ₂ ), calcium hydrogen phosphate (CaHPO ₄ ), ammonium dihydrogen phosphate ((NH ₄ ) H ₂ PO ₄ ), etc. Can do. Moreover, when using an organic compound, phosphine oxides can be used, for example.

  As the particle diameter of the zirconia crystal particles, a suitable one is appropriately selected.

  A binder may be added to the sintering composition. The presence or absence of the addition of the binder can be appropriately selected according to the purpose of manufacturing the sintered body. When using a binder, for example, an acrylic binder can be used.

  The mixing method may be either dry mixing or wet mixing. In the case of wet mixing, for example, water, alcohol or the like can be used as a solvent. Further, the mixing may be manual mixing or mechanical mixing. When the zirconia crystal particles before mixing form secondary particles, it is preferable to pulverize and mix the secondary particles as much as possible.

  Third, the sintering composition is pressure-molded into a desired shape. As the pressure molding method, a suitable method can be appropriately selected. The pressurizing pressure can be set to 20 MPa or more, for example. After the pressure molding, CIP (Cold Isostatic Pressing) may be further applied to the sintering composition at a pressure of 150 MPa or more, for example.

  Prior to pressure molding, the sintering composition may be made by granulating zirconia particles into granules. When a solvent is used during mixing, the solvent is first removed before pressure molding or pre-molding. For example, the solvent may be removed by a spray drier when granulated into granules, or may be removed by oven drying.

  The composition for sintering can also be processed into a desired shape by grinding, grinding, or the like after pressure molding.

  Fourth, before sintering, the sintering composition may be calcined to produce a calcined body. In this case, the calcination conditions are, for example, a calcination temperature of 800 ° C. to 1200 ° C. and a holding time of 1 hour to 3 hours.

  The calcined body can be processed into a desired shape by calcining or grinding after calcining.

  Fifth, the sintering composition or calcined body is fired to sinter the zirconia particles to produce a zirconia sintered body. The firing temperature is preferably 1350 ° C. or higher. When phosphorus element is contained, the firing temperature is preferably 1350 ° C. or higher. When the firing temperature is low, the cubic system is not sufficiently formed on the fired surface, and the effect of suppressing the low temperature deterioration cannot be sufficiently obtained. Moreover, the higher the firing temperature, the higher the effect of suppressing phase transition in low temperature degradation. For example, the zirconia sintered body of the present invention, which is preferably fired at a firing temperature higher than 1400 ° C., more preferably higher than 1425 ° C., can effectively suppress the phase transition to monoclinic crystal by hydrothermal treatment. it can. This is considered to be because the stabilizer moves to the surface layer by firing, and a part of the surface layer becomes cubic.

  Firing can be carried out in an atmospheric air atmosphere.

  Sixth, the zirconia sintered body may be further subjected to HIP treatment in order to improve the denseness.

  Seventh, the zirconia sintered body may be refired at 1350 ° C. or higher after being processed into a desired shape. Thereby, the re-fired surface can contain the cubic system again.

  In the above description of the method for producing a zirconia sintered body, the case where a desired amount of phosphorus element, boron element, aluminum oxide and silicon dioxide is not contained in the zirconia crystal particles has been described. The zirconia crystal particles may be originally included in the zirconia crystal particles, or a part of a desired amount may be included in the zirconia crystal particles. In that case, the addition amount of each element is adjusted in consideration of the contents of the phosphorus element-containing compound, boron, aluminum oxide and silicon dioxide in the zirconia crystal particles. For example, when a desired amount of silicon dioxide is contained in the zirconia crystal particles, it is sufficient to add only the phosphorus element-containing compound when preparing the sintering composition. Further, when a desired amount of silicon dioxide is contained in the zirconia crystal particles, a desired amount of the remaining silicon dioxide may be added together with the phosphorus element-containing compound when the composition for sintering is prepared. The rest is the same as the above method.

[Examples 1 to 18]
About the 1st-4th embodiment, the addition rate of each element differs, producing the zirconia sintered compact, the firing surface (exposed surface after sintering) of each zirconia sintered body, the inside (exposed after grinding a sintered surface) Surface) and refired surface (exposed surface after refired after grinding the fired surface) and the peak ratio of cubic crystals on the fired surface was calculated. Each zirconia sintered body was subjected to hydrothermal treatment, which is an accelerated test for low temperature deterioration, and the peak ratio of monoclinic crystals in the zirconia sintered body after hydrothermal treatment was calculated.

[Manufacture of zirconia sintered body]
Tables 1 to 6 show the mixing ratio of the raw materials in each example. The zirconia crystal powder used as a raw material is a partially stabilized tetragonal zirconia powder (manufactured by Noritake Company Limited) having a predetermined concentration of yttrium oxide (yttria) as a stabilizer in the crystal particles. The yttria concentration in the partially stabilized zirconia crystal particles was 3 mol% (shown as “3YZrO ₂ ” in Table 1), and several partially stabilized zirconia crystal powders having different stabilizer contents were not used. In Table 1, “Al ₂ O ₃ ” means aluminum oxide. The aluminum oxide used as a raw material is α-alumina having an aspect ratio of about 1. “B ₂ O ₃ ” means boron oxide, “SiO ₂ ” means silicon dioxide, and “Binder” means an organic binder added to improve moldability (for example, acrylic binder) Means. “X” means any one of bismuth, tin, germanium, and sulfur, and corresponds to “X” in Tables 2 to 5. Boron oxide was used as a boron-containing compound for adding boron. Bismuth oxide was used as a bismuth-containing compound for adding bismuth. Tin oxide was used as a tin-containing compound for adding tin. Germanium oxide was used as a germanium-containing compound for adding germanium. Sulfuric acid was used as the sulfur-containing compound for adding sulfur. Further, as Comparative Example 1, a zirconia sintered body in which boron was added but “X” was 0, that is, bismuth or the like was not added was also produced, and the same measurement as in Example was performed. “Bismuth and the like” means bismuth, tin, germanium, and sulfur.

Each numerical value in Table 1 will be described. The numerical value in the “base” column is the content (% by mass) of each of the partially stabilized zirconia and aluminum oxide with respect to the total mass of the partially stabilized zirconia and aluminum oxide in the sintering composition. The numerical value in the “addition rate” column indicates the addition rate with respect to the total mass (base) of partially stabilized zirconia and aluminum oxide in the sintering composition. The addition rate (A) of “X” and the addition rate (B) of “B ₂ O ₃ ” are shown in Tables 2 to 5, respectively. For example, in Example 3 shown in Table 2, in the composition for sintering, the base contains 92.6% by mass of 3YZrO ₂ and 7.4% by mass of aluminum oxide (100% by mass in total). Bismuth is added as “X”, and the mass of bismuth oxide corresponds to 0.1% (value of “A” shown in Table 2) of the total mass (100 mass%) of the base. It has been added. Boron oxide is added so that the mass of boron oxide corresponds to 0% to 0.3% (value of “B” shown in Table 2) of the total mass (100 mass%) of the base. The same applies to silicon dioxide and binder.

  The manufacturing method of a zirconia sintered compact is demonstrated. First, the partially stabilized zirconia crystal particles were crushed, and the raw materials were added in the formulations shown in Tables 1 to 6 and mixed in water to prepare a sintering composition.

  Next, the solvent was removed by a spray dryer and zirconia particles were granulated into granules. Next, the composition for sintering was shape | molded with the 30-MPa press, and it was set as the shape of diameter 19mm and thickness 2mm. Next, each composition for sintering was fired at 1450 ° C. for 1.5 hours to produce a zirconia sintered body. In this example, the composition for sintering was not subjected to HIP (Hot Isostatic Pressing) treatment, but when applied, for example, the HIP treatment was performed at 1400 ° C. and 170 MPa, It can be densified.

[Measurement of X-ray diffraction pattern of fired surface and calculation of peak ratio of cubic crystal]
In order to confirm the crystal structure of the zirconia sintered body of the present invention, the X-ray diffraction pattern (XRD) of the fired surface (exposed surface after sintering) was measured, and the peak ratio of cubic crystals was calculated. The X-ray diffraction pattern was measured using RINT-TTRIII (manufactured by Rigaku Corporation) at Cu-target, 50 kV, 50 mA. FIG. 1 shows an X-ray diffraction pattern of a fired surface of a zirconia sintered body having a bismuth addition rate of 0.2% and a boron oxide addition rate of 0.1% in Example 4 of Table 2. FIG. 4 shows an X-ray diffraction pattern of a fired surface of a zirconia sintered body having an addition rate of tin of 0.2% and an addition rate of boron oxide of 0.1% in Example 8 of Table 3. FIG. 7 shows an X-ray diffraction pattern of a fired surface of a zirconia sintered body having a germanium addition rate of 0.2% and a boron oxide addition rate of 0.1% in Example 7 of Table 4. FIG. 10 shows an X-ray diffraction pattern of a fired surface of a zirconia sintered body having a sulfur addition rate of 0.2% and a boron oxide addition rate of 0.1% in Example 10 of Table 5. FIG. 13 shows an X-ray diffraction pattern of a fired surface of a zirconia sintered body having an X addition rate of 0% and a boron oxide addition rate of 0% in Comparative Example 1 of Table 6. Moreover, the peak ratio of the cubic crystal of each zirconia sintered compact is shown in Tables 2-6. In Tables 2 to 5, “∞” means that the tetragonal peak is very small and the existence of the tetragonal system could not be substantially confirmed, and only the cubic system could be confirmed.

  In the X-ray diffraction pattern of the sintered surface of the zirconia sintered body to which phosphorus and boron are not added as shown in FIG. 13, there are two large peaks when 2θ ranges from about 34.5 ° to 35.5 °. These two peaks are both tetragonal peaks. A cubic peak is only slightly observed between the two peaks.

  On the other hand, in the X-ray diffraction pattern of the fired surface of the zirconia sintered body of the present invention shown in FIGS. The left peak is a tetragonal [002] peak and the right peak is a tetragonal [200] peak, while the middle peak at about 35 ° is a cubic [200] peak. . That is, it can be seen that cubic crystals are formed on the fired surface of the zirconia sintered body of the present invention.

  As shown in Tables 2 to 5, in any zirconia sintered body to which bismuth or the like was added, the presence of a cubic system was confirmed when the addition ratio was in the range of 0.001% to 1%. When the addition rate of bismuth or the like is kept constant and the addition rate of boron oxide is increased in the range of 0% to 0.3%, the peak ratio of cubic crystals increases, that is, the existence ratio of cubic crystals on the fired surface increases. ing. In particular, if the boron oxide addition rate was 0.05% or more, the presence of a cubic system could be reliably confirmed. Further, when compared with the comparative examples shown in Table 6, it can be seen that more cubic systems are formed in the zirconia sintered body of the present invention by the addition of bismuth or the like.

[Internal X-ray diffraction pattern measurement]
The internal X-ray diffraction pattern exposed by grinding the fired surface was measured. Grinding of the fired surface was performed by grinding with a # 400 diamond grindstone and then polishing with # 2000 diamond paste to grind the fired surface to a depth of at least 100 μm (note that the numerical values are in accordance with JIS standards) . FIG. 2 shows an X-ray diffraction pattern inside the zirconia sintered body having a bismuth addition rate of 0.2% and a boron oxide addition rate of 0.1% in Example 4 of Table 2. FIG. 5 shows an X-ray diffraction pattern inside a zirconia sintered body having an addition rate of tin of 0.2% and an addition rate of boron oxide of 0.1% in Example 8 of Table 3. FIG. 8 shows an X-ray diffraction pattern inside a zirconia sintered body having a germanium addition rate of 0.2% and a boron oxide addition rate of 0.1% in Example 7 of Table 4. FIG. 11 shows an X-ray diffraction pattern inside a zirconia sintered body having a sulfur addition rate of 0.2% and a boron oxide addition rate of 0.1% in Example 10 of Table 5. FIG. 14 shows an X-ray diffraction pattern inside a zirconia sintered body having a 0% addition rate of X and a 0% addition rate of boron oxide in Comparative Example 1 in Table 6.

  In any of the internal X-ray diffraction patterns, substantially no cubic system was observed. That is, the main crystal form inside the sintered body was tetragonal. This shows that the cubic system exists in the vicinity of the fired surface in the zirconia sintered body of the present invention.

  This is also observed in Japanese Patent Application No. 2010-185586 relating to a zirconia sintered body having a composition similar to that of the present invention. According to Japanese Patent Application No. 2010-185586, from the measurement result of the thin film X-ray diffraction pattern, there are many cubic systems in the region from the fired surface to a depth of 15 μm, particularly in the region from the fired surface to 5 μm. I found out. From this, it is presumed that the cubic distribution is the same for the zirconia sintered body of the present invention.

  According to Japanese Patent Application No. 2010-185586, the reason why the cubic system is formed on the fired surface is secondary ion mass spectrometry (SIMS) and X-ray photoelectron spectroscopy (XPS). From the measurement results of (2), it is considered that yttria as a stabilizer moves to the surface during firing, the yttria concentration on the surface becomes high, and only the surface is completely stabilized, that is, cubic.

[Measurement of X-ray diffraction pattern of refired surface]
The sintered zirconia sintered body with the fired surface ground and exposed inside was refired, and the X-ray diffraction pattern on the refired surface was measured. The ground sintered body was refired at 1450 ° C. for 1.5 hours. In addition, the process etc. which apply | coat a stabilizer to the surface of the ground sintered compact are not given at the time of rebaking. FIG. 3 shows an X-ray diffraction pattern of a refired surface of a zirconia sintered body having a bismuth addition rate of 0.2% and a boron oxide addition rate of 0.1% in Example 4 of Table 2. FIG. 6 shows an X-ray diffraction pattern of a refired surface of a zirconia sintered body having a tin addition rate of 0.2% and a boron oxide addition rate of 0.1% in Example 8 of Table 3. FIG. 9 shows an X-ray diffraction pattern of a refired surface of a zirconia sintered body having a germanium addition rate of 0.2% and a boron oxide addition rate of 0.1% in Example 7 of Table 4. FIG. 12 shows an X-ray diffraction pattern of a refired surface of a zirconia sintered body having a sulfur addition rate of 0.2% and a boron oxide addition rate of 0.1% in Example 10 of Table 5. FIG. 15 shows an X-ray diffraction pattern of a refired surface of a zirconia sintered body having a 0% addition rate of X and a 0% addition rate of boron oxide in Comparative Example 1 in Table 6.

  As shown in FIGS. 2, 5, 8, and 11, the sintered body whose ground surface was ground, that is, the sintered body before refiring in which the inside was exposed, was not reconfirmed even though a cubic peak was not confirmed. A cubic peak was confirmed again by firing. On the other hand, as shown in FIG. 15, in the zirconia sintered body to which bismuth or the like and boron were not added, a cubic peak was not confirmed even after refiring. From this, in the zirconia sintered body of the present invention, even if the fired surface is ground and the surface where the main crystal system is a tetragonal system is exposed, the stabilizer is applied by refiring the surface, etc. The sintered body can be coated again with a layer containing a large amount of the cubic system without any other treatment. This is considered to be due to the phenomenon that a part of the stabilizer contained in the sintered body moves to the exposed surface due to the addition of bismuth or the like and boron. Therefore, the zirconia sintered body of the present invention can produce a product having high hydrothermal deterioration resistance by being fired after being processed into a desired shape.

[Hydrothermal treatment]
Next, the zirconia sintered body of each example was subjected to hydrothermal treatment, which is an accelerated test for low temperature deterioration. The test method conforms to ISO13356 except for temperature, pressure and processing time. First, pure water for heating and pressurization is put in a heat and pressure resistant container (autoclave), and a sample is set in the heat and pressure resistant container so as not to be immersed in water. Next, after the lid of the heat and pressure resistant container was fixed with a bolt, the inside of the heat and pressure resistant container was heated to 180 ° C., and the pressure in the heat and pressure resistant container was set to about 1.0 MPa (10 atm). Each specimen was held in this state in a heat and pressure resistant container for 5 hours.

[X-ray diffraction measurement]
Next, in order to confirm the monoclinic peak ratio in the sample of each example after hydrothermal treatment, the X-ray diffraction pattern of the surface of each sample after hydrothermal treatment was measured. The X-ray diffraction pattern was measured using RINT-TTRIII (manufactured by Rigaku Corporation) at Cu-target, 50 kV, 50 mA. Tables 2 to 6 show the peak ratios of monoclinic crystals of the respective zirconia sintered bodies. The monoclinic peak ratios shown in Tables 2 to 6 are monoclinic with 2θ of around 28 ° relative to the height of the peak existing near the position where the [111] peak derived from tetragonal crystal with 2θ of around 30 ° occurs. It is a numerical value obtained by multiplying the ratio of the height of peaks existing near the position where the derived [11-1] peak occurs by 100.

  The peak ratio was measured after smoothing all the diffraction patterns using Jade 6 (provided by Rigaku Corporation), which is an X-ray diffraction pattern analysis software. In the background process, the background point threshold σ was set to 10.0. In the examples of the present invention, the peak ratio was obtained under the same conditions.

  Looking at the change in the peak ratio of the monoclinic crystal after hydrothermal treatment relative to the change in the peak ratio of the cubic crystal, the peak ratio of the monoclinic crystal increases as the cubic peak ratio increases in any zirconia sintered body. It tends to be lower. That is, the hydrothermal deterioration is improved as the cubic crystal existing ratio on the fired surface increases. In particular, when the cubic peak ratio × 100 is 100 or more, the monoclinic peak ratio tends to be very small. From this, it was found that the progress of hydrothermal deterioration can be suppressed by increasing the content of cubic crystals on the fired surface. That is, it can be seen that the zirconia sintered body according to the present invention has high hydrothermal deterioration resistance.

  16 to 19 show graphs in which the peak ratio of monoclinic crystals is plotted against the addition rate of boron oxide. FIG. 16 is a graph when bismuth is added. FIG. 17 is a graph when tin is added. FIG. 18 is a graph when germanium is added. FIG. 19 is a graph when sulfur is added.

  As can be seen from Tables 1 to 5, when only bismuth or the like was added (that is, when the boron addition rate was 0), there was no significant effect on the formation of cubic crystals and the suppression of phase transition. However, when bismuth or the like and boron are added in combination, as shown in FIGS. 16 to 19, as compared with Comparative Example 1 in which only boron is added (that is, the addition rate of bismuth or the like is 0), monoclinic crystal. It can be seen that the peak ratio of can be lowered. That is, it has been found that when bismuth or the like is combined with boron, the synergistic effect promotes the formation of cubic crystals in the vicinity of the fired surface, thereby enhancing the effect of suppressing phase transition due to hydrothermal treatment.

  In addition, when FIG. 19 is seen, in Examples 15-17 which added sulfur, the production | generation of the monoclinic crystal | crystallization increased as the addition rate of sulfur increased. From this, about sulfur, a higher effect may be acquired by making an addition rate still lower than 0.001%.

  In this embodiment, aluminum oxide is not added. However, in Japanese Patent Application Nos. 2009-192287 and 2010-185586, which are incorporated in this document, the formation of cubic crystals and the suppression of phase transition can be achieved even when aluminum oxide is added. In the present invention, it is considered that aluminum oxide can be added.

[Examples 19-26]
In order to investigate how much boron added during the preparation of the sintering composition remains in the zirconia sintered body, the boron content in the zirconia sintered body was measured. The content measurement was performed for samples with different boron addition rates. The measurement was performed using an ICP emission spectroscopic analyzer (manufactured by SII Nanotechnology, Inc .; model number SPS3500) after dissolving each sample. The measurement was performed twice from the sample pretreatment. Table 7 shows the average value of the measurement results of boron. The “addition rate” in Table 7 indicates the addition rate with respect to the total mass of partially stabilized zirconia and aluminum oxide in the sintering composition. “Content ratio” indicates a content ratio (average value of two measured values) in the zirconia sintered body. Since the zirconia sintered body is substantially composed of partially stabilized zirconia and aluminum oxide, the “addition ratio” and the “content ratio” can be compared and contrasted. The “residual rate” is a ratio of the “content rate” to the “addition rate”.

  Under sintering conditions, boron tends to burn out easily. In particular, it is considered that the lower the addition rate, the lower the residual rate and the easier the burning. Even if boron eventually burns out, it is considered that it contributes to the movement of the stabilizer to the surface layer during firing, that is, the formation of a cubic system in the surface layer. Depending on the sintering conditions (for example, maximum temperature, firing curve, firing atmosphere), there is a possibility that the residual ratio of phosphorus and boron can be made higher.

  In the above description, when calculating the number of moles of phosphorus element with respect to 1 mol of zirconium oxide (molecular weight 123.22), the stabilizer is used in consideration of the presence of a stabilizer (for example, yttrium oxide) and other compounds. The zirconium oxide content in the partially stabilized zirconia powder contained in 3 mol% is 94.5% by mass (regardless of the content of other elements).

  In the above description, numerical values indicating the upper limit and the lower limit in the range represented by “to” are included in the range.

  Although the zirconia sintered body of the present invention, the composition for sintering the zirconia sintered body, and the calcined body have been described based on the above embodiment, the present invention is not limited to the above embodiment. It goes without saying that various modifications, changes and improvements can be included in the above embodiments within the scope and based on the basic technical idea of the present invention. Further, various combinations, substitutions, or selections of various disclosed elements are possible within the scope of the claims of the present invention.

  Further problems, objects, and developments of the present invention will become apparent from the entire disclosure of the present invention including the claims.

  The zirconia sintered body of the present invention has advantages such as high strength, high toughness, long life, high reliability, small dimensional change, non-coloring property / translucency, etc., dental materials such as prosthetic materials, ferrules, sleeves, etc. Connection parts for optical fibers, various tools (for example, grinding balls, grinding tools), various parts (for example, screws, bolts and nuts), various sensors, electronic parts, ornaments (for example, watch bands) It can be used for

Claims (14)

Having partially stabilized zirconia as the matrix phase;
Boron (B) element is contained 3 × 10 ⁻⁴ mass% to 3 × 10 ⁻¹ mass% with respect to the mass of the zirconia sintered body,
Bismuth (Bi) elements, tin (Sn) element further comprises at least one element of 及 beauty sulfur (S) element,
When it contains a bismuth element, it contains 0.001% by mass to 1% by mass with respect to the mass of the zirconia sintered body,
When containing tin element, it contains 0.001 mass%-1 mass% with respect to the mass of a zirconia sintered compact ,
A zirconia sintered body comprising 0.001% by mass to 0.1 % by mass with respect to the mass of the zirconia sintered body when elemental sulfur is contained.   The zirconia sintered body according to claim 1, further comprising 0.005 mass% to 1 mass% of phosphorus (P) element with respect to the mass of the zirconia sintered body.   The zirconia sintered body according to claim 1 or 2, further comprising 0.2% by mass to 25% by mass of aluminum oxide based on the mass of the zirconia sintered body.   The zirconia sintered body according to any one of claims 1 to 3, further comprising 0.03 to 3% by mass of silicon dioxide with respect to the mass of the zirconia sintered body. In the X-ray diffraction pattern on the fired surface, the ratio of the height of the peak existing near the position where the cubic [200] peak occurs to the height of the peak existing near the position where the tetragonal [200] peak occurs Is 0.4 or more,
In the X-ray diffraction pattern in the region where the depth from the fired surface is 100 μm or more, near the position where the cubic [200] peak occurs relative to the height of the peak existing near the position where the tetragonal [200] peak occurs The ratio of the heights of the peaks existing in the zirconia is 0.3 or less, the zirconia sintered body according to any one of claims 1 to 4. When the fired surface or the exposed surface is cut, the [200] peak derived from a cubic crystal is present in the vicinity of the position where the [200] peak derived from a tetragonal crystal is generated in the X-ray diffraction pattern. When the surface having a peak height ratio of 0.3 or less is exposed and then refired,
In the X-ray diffraction pattern on the refired surface, the height of the peak existing near the position where the [200] peak derived from the cubic crystal is higher than the height of the peak existing near the position where the [200] peak derived from the tetragonal crystal is generated. Ratio is 0.4 or more, The zirconia sintered compact as described in any one of Claims 1-5 characterized by the above-mentioned.   In an X-ray diffraction pattern in a region where the depth from the refired surface is 100 μm or more, a [200] peak derived from a cubic crystal is generated with respect to the height of the peak existing near the position where a [200] peak derived from a tetragonal crystal is generated. The zirconia sintered body according to claim 6, wherein a ratio of heights of peaks existing in the vicinity of the position is 0.3 or less. When the zirconia sintered body is subjected to a low temperature deterioration acceleration test at 180 ° C. and 1 MPa for 5 hours,
In the X-ray diffraction pattern on the surface of the zirconia sintered body after the accelerated low temperature degradation test, [11-1] derived from monoclinic crystals with respect to the height of the peak existing near the position where the [111] peak derived from tetragonal crystals occurs. The zirconia sintered body according to any one of claims 1 to 7, wherein a ratio of heights of peaks existing near positions where peaks occur is 1 or less.   The zirconia sintered body according to any one of claims 1 to 8, which is sintered at 1350 ° C to 1550 ° C. Containing partially stabilized zirconia particles,
Boron (B) element is contained 4 × 10 ⁻⁵ mol to ⁵ × 10 ⁻² mol with respect to 1 mol of zirconium (IV) oxide,
Bismuth (Bi) elements, tin (Sn) element contains at least one element of 及 beauty sulfur (S) element,
When it contains a bismuth element, it contains 6 × 10 ⁻⁶ mol to 7 × 10 ⁻³ mol per 1 mol of zirconium (IV) oxide,
When tin element is contained, 1 × 10 ⁻⁵ mol to ² × 10 ⁻² mol are contained per 1 mol of zirconium (IV) oxide ,
When containing elemental sulfur, zirconium oxide (IV) 4 × respect ^{1mol 10 -5 mol~5 × 10 - 3} mol sintered composition of the zirconia sintered body characterized by containing.   A composition for sintering a zirconia sintered body, wherein the zirconia sintered body according to any one of claims 1 to 9 is obtained by sintering at 1350 ° C to 1650 ° C. Containing zirconia containing a stabilizer,
Boron (B) element is contained 4 × 10 ⁻⁵ mol to ⁵ × 10 ⁻² mol with respect to 1 mol of zirconium (IV) oxide,
Bismuth (Bi) elements, tin (Sn) element contains at least one element of 及 beauty sulfur (S) element,
When it contains a bismuth element, it contains 6 × 10 ⁻⁶ mol to 7 × 10 ⁻³ mol per 1 mol of zirconium (IV) oxide,
When tin element is contained, 1 × 10 ⁻⁵ mol to ² × 10 ⁻² mol are contained per 1 mol of zirconium (IV) oxide ,
When containing elemental sulfur, 4 × ¹⁰ -5 mol~5 × ¹⁰ relative to zirconium oxide (IV) 1 mol ^- calcined body of zirconia sintered body, characterized by 3 mol containing.   A calcined body of a zirconia sintered body that becomes a zirconia sintered body according to any one of claims 1 to 9 by sintering at 1350 ° C to 1550 ° C.   A calcined zirconia sintered body, which is formed by calcining the sintering composition according to claim 10 or 11 at 800 ° C to 1200 ° C.

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