JPS5852949B2 - How to manufacture ceramic parts - Google Patents

Description

[Detailed description of the invention] TECHNICAL FIELD The present invention relates to a ceramic product and a method for manufacturing the same.

According to the present invention, the manufacturing method of the ceramic product is such that the total number of silicon and aluminum atoms relative to the total number of oxygen and nitrogen atoms is in the range from 09735 to 0.77, and the plurality of compounds react in the subsequent sintering process. from a plurality of compounds containing silicon, aluminum, oxygen and nitrogen to produce a single phase ceramic having the following general formula %, where 2 is between 0.38 and 1.5. and a second component consisting essentially of 0.1 to 10% by weight of at least one of another element, namely yttrium, scandium, cerium, lanthanum, and ranknide metals. form a powder mixture containing at least 1
at a constant temperature between 1600° C. and 2000° C. with or without pressure to create a ceramic material containing at least 80% by volume of the single phase ceramic material together with a second phase containing another element as mentioned above. sintering the mixture in a protective atmosphere of pressure for a time ranging from at least 10 minutes to at least 5 hours, with selected short periods of time at elevated temperatures.

In the method described in the previous section, the first component compounds are obtained by dividing the sum of all silicon and aluminum atoms of those compounds by the sum of oxygen and nitrogen atoms present, and the quotient is 0.735 and 0.
．． 77, more preferably between 0.745 and 0.76.

The mixture of the two components is then heated to 1600° C. in a protective atmosphere, preferably a non-oxidizing atmosphere and more preferably a reducing atmosphere.
to 2000° C. for a time sufficient to produce at least 80% by volume of the silicon aluminum oxynitride ceramic material as defined by the above formula.

This required sintering time increases with decreasing temperature, so that at a sintering temperature of 2000°C it is only 10 minutes, but at a sintering temperature of 1600°C the sintering time increases by at least 5 minutes.
It takes time.

The resulting ceramic material has a hexagonal β-phase silicon nitride-based crystal structure that expands the lattice to accommodate aluminum and oxygen substituents.

The components forming the first component of the initial mixture are typically silicon nitride, aluminum nitride, alumina and silica, with some of the silica and alumina being present as inherent impurities in the silicon nitride and aluminum nitride, respectively. .

However, it must not contain externally added silica.

Such added silica is volatile and highly reactive at high temperatures.

Therefore, at high temperatures at which the ceramic product aimed at by the present invention is obtained, silica quickly evaporates and the compositional ratio is disturbed, making it impossible to obtain the desired ceramic product.

Additionally, mixtures of added silica and silicon nitride powder have poor flow properties, which often results in irregular mold filling during molding, and may also result in films in the final product.

On the other hand, silica, which exists as an inherent impurity in silicon nitride, is strongly bonded to the silicon nitride and therefore has no volatility or reactivity, unlike silica added as a separate component. Therefore, the above-mentioned problem does not occur.

Alternatively, the first component has the general formula 8i6-zAlzOzN3
It may also be limited by intermediate ceramics containing silicon aluminum oxynitrides and silicon nitrides that do not comply with z.

Preferably, the intermediate ceramic silicon aluminum oxynitride has a hexagonal crystal structure and follows the approximate formula 5iA140°N.

Additionally, this intermediate ceramic was heated to 1200°C in a nitriding atmosphere.
The alumina, aluminum and silicon are heated to between 1500°C and 1400°C, the heating rate being controlled to almost prevent exotherm, and then the nitrided mixture is sintered at a temperature between 1500°C and 1800°C. It is preferable to form.

Different intermediate ceramics are used at 1200℃ and 20℃.
The powder mixture of alumina, aluminum nitride and silicon nitride may be heated in a protective atmosphere, preferably a non-oxidizing atmosphere or more preferably a reducing atmosphere, at a constant temperature between 0.000C and formed.

In the method described above, the relative proportions of the compounds present in the first component of the mixture are determined by adjusting the relative proportions of the compounds present in the first component of the mixture.
Let B z be created, where 2 is 0.
38 and 1.5, as it has been found that binary values within these limits produce unique products with high strength even when sintering is carried out without pressure. This is because the.

On the other hand, if the z value is slowed to below 0.38, the material becomes different because it is sintered without being pressurized, and if the z value is increased to 1.5 or above, this material becomes different. Reduces the strength of the product.

Note that the relative ratio of the first component compound is 0.735 and 0.
．． The above-mentioned atomic ratio is between 77 and 77.

It has been found that if this ratio falls below 0.735, the mixture becomes too oxygen rich.

This results in the production of an excessive amount of glass during sintering, which not only has a negative impact on the high temperature strength properties of this product, but also
It was also found that it had an adverse effect on low temperature strength properties.

Furthermore, it was found that this glass could not be removed by subsequent heat treatment as detailed below.

In contrast, when the atomic ratio exceeds 0.77, insufficient oxygen is present to form the glass necessary to effect the bonding of the product.

Within the allowable atomic ratio from 0.735 to 0177,
It has been found that best results are obtained when this ratio is between 0.745 and 0.76, with the actual ratio varying depending on the intended use of the product.

Therefore, if the above atomic ratio is between 0.745 and 0.75, the final product will have a relatively high glass content and therefore good low temperature properties, but the strength will be significantly reduced at high temperatures. .

On the other hand, if the atomic ratio is between 0.75 and 0.76, the final product will have a relatively low glass content and therefore a low temperature strength lower than that of high content glass materials, but It has been found that up to high temperatures the strength changes little or does not decrease, and in fact in some cases increases with increasing temperature.

A tolerance range of 0.1 to 10% by weight relative to the second component in the starting mixture is selected on the basis of providing a satisfactory glass content in the sintered product.

The elements chosen as the second component are cerium, yttrium, scandium, lanthanum or one of the lanthanide series, since they have highly refractory oxides, which together with silica and alumina are highly Creates a melting point glass, which allows the product to be used at higher temperatures than can be used with lower melting point glasses.

Among the elements selected as the second component, yttrium is preferred, since the presence of yttrium in the sintered mixture
This is because it was found that a product with high strength can be produced even without applying pressure.

By carrying out the method described above, a sintered ceramic is produced containing at least 80% by volume of silicon aluminum oxynitride according to the formula described above together with a glass phase containing elements of the yttrium, scandium, cerium, lanthanum or lanthanide series. It will be understood that this results in the formation of objects.

As mentioned above, the presence of a glass phase helps bond the sintered product, but tends to reduce the high temperature properties of the final component.

However, the amount of glass phase in the sintered product is determined by subjecting this product to a final heat treatment process that raises the temperature of the product to within 200°C of the melting point of the glass (i.e. up to 1400°C in the case of yttrium glass) and then It has been found that this product can be reduced by cooling and crystallizing at least a portion of the glass into a ceramic phase, usually containing metallic aluminum garnet.

In this way, the advantageous properties of the glass can be used in aiding the sintering operation, while at the same time reducing or eliminating the detrimental effects of the glass on the properties of the final product.

A similar effect can be achieved by controlling the cooling of the product obtained by the sintering operation, so that the desired crystallization can be effected directly.

When the other element is yttrium, the crystallization is carried out by cooling from the sintering temperature at a rate between 70°C and 90°C per hour to a holding temperature of 1300°C to 1500°C and then holding for 4 to 6 hours. This can be carried out suitably by allowing it to cool to room temperature.

Next, the present invention will be explained in more detail with reference to Examples.

In these examples showing fracture average values for sintered ceramic products, it is clear that the values quoted were obtained by subjecting a number of polished samples with a cross section of 0.3 cm square to three-point bending tests. You should understand.

That is, the test consisted of loading each sample at the midpoint of the two knife supports while supporting them approximately 20 wit (374 inches) apart.

The relationship between the load (b) required to break each sample and the rupture modulus (MR) is expressed by the following equation: where l - Suhan between the supports g - Acceleration due to gravity g - Sample in the direction perpendicular to the load The width d - the average depth of the samples in the direction of the load is calculated from the number of samples tested.

The Weibull coefficient is 1.2 to the above average value.
and divided by the standard deviation.

In a first embodiment of the present invention, a sintered ceramic material is made from a starting mixture having a first component, said first component having an average particle size of 2 microns and with a 4% weight of silica as an inherent impurity. Koch-L as type 8006H contains 92 parts by weight of silicon nitride powder containing 899 parts by weight of one-phase material and 6 parts by weight of alumina as an inherent impurity with an average particle size of 6 microns.
5 parts by weight of an aluminum nitride powder, commercially available from Co., Ltd., and 3 parts by weight of an alumina powder, supplied by Line as type B, having an average particle size of 0.05 microns.

Therefore, allowing for impurities, the actual composition of the first component of this mixture is 88.32 parts by weight silicon nitride, 4.7 parts by weight aluminum nitride, 3.3 parts by weight alumina, and 3.6 parts by weight silica.
It is 8 parts by weight.

Therefore for every 100 g of the first component there is 53.068 g of silicon donated by silicon nitride and another 1.721 g donated by silica, so the total silicon content is 54.789 g or 1.950 g atoms. be.

It is easy to repeat this method for other elements and adjust the first component to contain 0.179 gram atoms of aluminum, 2.633 gram atoms of nitrogen, and 0.220 gram atoms of oxygen. be.

The ratio of the total number of silicon and aluminum atoms to the total number of nitrogen and oxygen atoms is 0.746.

Additionally, this mixture is manufactured by Rare Earth Products Limited (Rare Earth Products Limited) with particle sizes on the order of 1 micron.
6 parts by weight of Ittria powder sold by Earth Products Limited)
Contains as an ingredient.

The required amount of starting material to make the above mixture is colloid milled using isopropyl alcohol as carrier liquid and after repeating this operation 6 times the resulting mixture is
Sieving was performed using a sieve with a mesh size of 50 microns.

After sieving, the mixture was heated to about 140 ox in a rubber bag.
, /, , 2 (20,000 p, s, i) to produce a preform with a working density of 1.6 g/cIrL3.

The resulting preform is then provided with a protective surface coating of silica with a 50 weight strip of boron nitride, the coating having a thickness of about 0.25 to 0.5 mm (0.01 mm).
~0.02 inch).

The coating material is applied to the preform as a suspension of a mixture of iso-butyl-methyl-ketone with 5 to 10 volumes of collodion;
Contains 0 parts by weight.

The coated preform is then embedded in a powdered boron nitride protective medium in a graphite crucible and heated to a sintering temperature of 1880° C. for 80 minutes without pressure.

The preform was then held at this temperature for a further 60 minutes and after cooling and removal from the graphite crucible was found to have an average modulus of rupture at 25° of 750 MN m@-2, a density of 3.152 and a Weibull modulus of 14.

Furthermore, the weight loss during this sintering operation is only 0.4%.
It was found that the final product contained more than 90 volumes φ of a single phase compound according to the following formula.

Si6-zAlzN3-zOz Here 2 is equal to approximately 0.5.

The average rupture modulus of the product of the first sample was measured at 1255°C and was found to have decreased to 379 MNm''.

Creep measurements of the material at 1225°C under a load of 77 MN m-2 revealed that this product had a creep rate of 0.05% in 1 hour.
It can be seen that there is an increase in

This indicates the presence of a dispersed glass phase.

Similarly, the product of the first sample was embedded in a graphite crucible and heated to 1400°C for another 60 minutes without applying pressure.
A secondary heat treatment was performed by heating to a temperature of .

The sintered product was then held at this temperature for a further 5 hours and then cooled.

In taking out this heat-treated product from the graphite crucible, 2
Average rupture coefficient 705MNm” and Weibull coefficient 1 at 5°C
1, but the creep at 1227°C was so improved that it took 11 hours for the product to undergo 0.05% creep when loaded with 77 MNm''.

The result of the X-ray diffraction analysis test of the heat-treated product is z = 0
．． In addition to the single phase ceramic of the above general formula having 5, yttrium aluminum garnet (3Y2
0s 5A (120 g) was added.

Similarly, the creep values indicate that most of the glass in the initial sample was crystallized during this heat treatment, forming yttrium aluminum garnet, although a small amount of glass still remained.

In the second example, the starting materials and treatment methods are similar to those in the first example, but the composition of the 1st part of the initial mixture is 92 parts by weight of silicon nitride, 6 parts by weight of aluminum nitride, and 2 parts by weight of alumina. Therefore, the atomic ratio of silicon and aluminum to nitrogen and oxygen is 0.75.

As mentioned above, the second component of this mixture is constituted by 6 parts by weight of Ittria.

This sintered product has an average modulus of rupture of 564 MN at 25°C.
m-2, density 3.175 and Weibull coefficient 16, with a weight loss during sintering of 0.44%.

X-ray diffraction analysis of this product revealed an amount equivalent to well over 6 volumes of IJum silicon dealuminum oxynitride Y
2SiA105N) and the above general formula having z = 0.5 exist with a capacity of 90 or more.

Creep measurements on this material at a load of 77 MNm'' and 1227°C show that the product reaches a creep of over 0.05 in 32 hours, thus reducing the amount of glass compared to the first sample. can be observed.

This second sample of product was reheated and subjected to the same conditions as in the previous example.

The product thus formed has an average modulus of rupture of 709 MNm'' at 25 °C and a Weibull coefficient of 8 and a
In a creep test under a load of 77 MNm'', the product reached 0.05% creep in 40 hours, indicating further reduction in the amount of glass.

The results of X-ray diffraction analysis of the heat-treated product show that in addition to the single-phase ceramic of the above general formula with z==0.5, there is also an amount of yttrium silicon aluminum oxynitride that is equivalent to more than 2 volumes, as well as more than 3 volumes. It showed the presence of a corresponding amount of yztrium aluminum garnet.

In the third example, the starting materials and processing method of the first example are again repeated, but the composition of the first component of the initial mixture is 92 parts by weight of silicon nitride, 7 parts by weight of aluminum nitride, and 1 part by weight of alumina.
It is expressed as parts by weight, so the above atomic ratio is 0.753.
It becomes.

The mixture further contains 6 parts by weight of ittria as a second component.

The obtained product has a density of 3.141°, an average rupture coefficient of 520 MN m'' at 25 °C and a Weibull coefficient of 15, and when increasing the temperature to 1225 °C, the average rupture coefficient of 90 to 608 MN m do.

As a result of creep measurement at a load of 77 MN m-2 and a temperature of 1227°C, the creep of this material was 0.05% in 8.5 hours.
? was reached, thus indicating the presence of a small amount of dispersed glass phase.

The results of X-ray diffraction analysis show that this material contains more than 90 volumes of single-phase compounds according to the general formula above, where 2 equals about 0.5.

It also shows the presence of yttrium silicon aluminum oxynitride in an amount equivalent to 5 volumes.

The product of Example 3 was converted to Example 1 using the same conditions in order to crystallize the glassy phase and at the same time convert the yttrium silicon aluminum oxynitride to yttrium aluminum garnet, thus improving the high temperature properties. A reheat cycle was applied as in the case.

The product thus formed has a Weibull coefficient of 1
1, and the average rupture modulus is 618 MNm'' at room temperature, 1
It was found to have a temperature of 602 MNm'' at 225°C.

Furthermore, creep test results at a load of 77 MN m'' and 1227° C. show that the product reaches a creep of 0.05% in 70 hours, indicating a significant weight loss of the glass phase.

The results of X-ray diffraction analysis of the heat-treated product indicate the presence of more than 90 volumes of single-phase ceramic according to the above general formula where 2 is about 0.5, along with an amount of yztrium aluminum garnet equivalent to well over 4 volumes. Show that.

In addition, an amount of α-bolastonite (α-
A phase with a structure similar to that of Wol Ia-stsnite) is shown.

The fourth example of the present invention was carried out in the same manner as the third example except that the temperature treatment step was changed.

The cooled preform was then heated to 1880° C. over 1.5 hours and held at this temperature for 1 hour.

The sintered product was cooled to 1400° C. over 17 minutes, held at this temperature for 5 hours, and then cooled to room temperature.

After removal from the boron nitride protective medium, X-ray diffraction analysis of the product revealed that the single-phase ceramic according to the above general formula with z = 0.5 corresponds to more than 90 volumes and more than 8 volumes. It was found to contain thorium aluminum garnet.

The average rupture modulus at 1225 °C and 1370 °C is 622 MNlTl-2 and 605 MNm” respectively, whereas the average rupture coefficient at 25 °C is 535 MN m−2,
The Weibull coefficient was 9.

A creep test at 1227 DEG C. under a load of 77 MN m'' showed that the material did not reach a creep of 0.05% even after 120 minutes, indicating that there was almost no glass phase in the product.

From the fourth example of the present invention, it can be seen that the formation of the second ceramic phase involves a controlled cooling step of the mixture from the sintering temperature, rather than obtaining a product that requires a secondary heat treatment cycle. It will be understood that this is more effective.

In the fifth example of the present invention, the starting composition of the second example was subjected to the sintering and cooling treatment of the fourth example.

Subsequent X-ray diffraction analysis showed that the product contained more than 90 volumes of a single-phase ceramic of the above general formula with z = 0.5 together with an amount of yztrium aluminum garnet corresponding to 7 volumes. It shows that

The average modulus of rupture at 25°C is 55 with a Weibull coefficient of 1.4.
5MNm''.

The rupture modulus at 1225°C was found to increase to 574 MNm''.

In the sixth example of the present invention, the starting composition of the first example was subjected to the sintering and cooling treatment of the fourth example.

X-ray diffraction analysis of this product revealed that 2=0
．． This indicates that the single-phase ceramic of the above general formula of No. 5 contains 90 or more volumes.

The average modulus of rupture measured at 25°C is the Weibull coefficient of 13
It turned out that the amount was 651 MNm.

In all of the above examples, the ratio of the total number of aluminum and silicon atoms to the total number of oxygen and nitrogen atoms in the first component of the starting mixture is 0.747 or greater, and the heat treatment of the sintered ceramic product The results show that crystallization reduces the glass phase and improves the high temperature properties of the product.

Furthermore, it is recognized that the high-temperature properties due to heat treatment not only improve as the above-mentioned atomic ratio increases, but also improve when no heat treatment is performed.

In contrast, in Example 7, the method of Example 1 is repeated, with the second component of the starting mixture again being 6 parts by weight of ittria, while the first components of silicon nitride, aluminum nitride and alumina are each The ratio was set to 92:4:4.

Therefore, the above atomic ratio is 0.745.

After sintering, X-ray analysis of the product revealed that it contained more than 90 volumes of single-phase ceramic of the above general formula with a ratio of about 0.5 to 2, with the remainder being glass.

The rupture modulus of this product at room temperature is 733 MN m-2 with a Weibull coefficient of 14, and the rupture modulus at 1225 °C is 274
MNm”.

Load 77MNm'', creep at 1227℃ is 0.7
It reached 0.05% in hours.

This product was heated at a temperature of 1400°C for 5 hours to
By carrying out the heat treatment as in the example and then allowing it to cool, some yttrium aluminum garnet was formed.

However, due to the high glass content, heat treatment has little effect on the high temperature properties of the product.

To illustrate the effect of varying the binary value of silicon aluminum oxynitride in this ceramic product, a product containing silicon aluminum oxynitride with a binary value of 0.38 was prepared in an eighth example.

The starting materials for this product are 94 parts by weight of silicon nitride, 6 parts by weight of aluminum nitride and 6 parts by weight of ittria.

Therefore, the first component of the mixture composed of silicon nitride and aluminum nitride has the above atomic ratio of 0.75.

This mixture was worked up as in the first example and the product obtained after sintering at 1880°C had a rupture modulus of 520 M at 25°C.
It was found that the Nm -2 Weibull coefficient was 8, and that the desired silicon aluminum oxynitride was contained in an amount of 80 volumes or more.

In Example 9, a ceramic product containing more than 80 volumes of silicon aluminum oxynitride with a binary value of 1.5 was prepared.

The starting mixture was composed of 70.6 parts by weight of silicon nitride, 16.35 parts by weight of aluminum nitride, 6 parts by weight of silica and 7.05 parts by weight of alumina, with the above atomic ratio of 0.7.
5 and further contains 7 parts by weight of ittria.

The sintering process was carried out in the same manner as in the first example, and the resulting product had a density of 3, a rupture coefficient of 550 MNm at 15.25°C,
The Weibull coefficient was 10 and the weight loss during sintering was 1.5 pounds.

In a tenth example of the invention, Aluminum Co. has a particle size of about 20 microns.
42 parts by weight of aluminum, commercially available from Union Carbide Co., Ltd.
silicon-14 supplied by de Limlted)
A mixture consisting of parts by weight and 44 parts by weight of alumina having a nominal particle size of 0.05 microns and marketed by Linde as Type B was introduced into an alumina boat and then heated in a nitriding furnace. did.

The nitriding atmosphere supplied to the furnace was 64% nitrogen and 6% hydrogen.
and 30% argon, and the temperature was carefully controlled during the nitriding by thermocouples in the reaction mixture and in the furnace wall, respectively, to prevent temperature overrun.

In particular, compare the temperatures recorded by these thermocouples and, if the temperature of the mixture is above the temperature of the furnace wall, stop supplying the nitriding atmosphere until the temperature of the mixture falls below the temperature of the furnace wall. .

The schedule for nitriding to proceed with minimal interruption is as follows: (a) Raise the temperature to 500°C at a heating rate of 100°C/hour;
Hold for 24 hours, (b) Raise the temperature from 500°C to 600°C at the above rate and hold for 7 hours, (c) Raise the temperature from 600°C to 1000°C at the above rate,
Hold for 24 hours, (d) Raise the temperature from 1000°C to 1100°C at the above rate and hold for 18 hours, (e) Raise the temperature from 1100°C to 1200°C at the above rate and hold for 5 hours, (f) The temperature was further increased to 1300°C at the above rate, and the temperature was increased to 20°C.
(g) Further raise the temperature to 1350°C at the above rate,
Hold for 6 hours.

After completing the edge heat treatment, the nitrided mixture is cooled in a furnace with an argon atmosphere, and then taken out from the furnace.

This material is then coarsely crushed and ground to a particle size of less than 500 microns, after which approximately 1000 Kp/Cl1
2 (15000 ps i ), the pellet is then introduced into a graphite crucible and embedded in boron nitride powder to form a protective atmosphere for subsequent sintering operations.

Next, the temperature of the crucible is increased from room temperature to 1500-2000℃.
Preferably, the temperature is raised to 1800° C. for 1.5 hours and then maintained at this temperature for 1 hour.

Apart from some unconverted oxides, the sintered product obtained consists almost entirely of a single phase silicon aluminum oxynitride with a hexagonal structure and according to the approximate formula 5iA1402N4. Ru.

The material thus constitutes a ceramic phase distinct from the single-phase compound based on a hexagonal β-phase silicon nitride lattice, said compound forming the main component of the ceramic product of the invention.

For convenience, this additional ceramic phase is hereinafter referred to as the 15R phase, while compounds based on a hexagonal β single-phase silicon nitride lattice are designated by the reference symbol β'.

After removal from the graphite crucible, the 15R sintered product was coarsely ground and then finely ground to an average particle size of 7 microns.

Then 12 parts by weight of the 15R product were mixed with 88 parts by weight of the silicon nitride powder of the first example, so that the ratio of the number of silicon to aluminum atoms to the number of nitrogen and oxygen atoms was 0.747.
Create the first component.

Six weights of ittria from Example 1 were then added to this first component and the sintering process of Example 1 was then repeated to prepare the final product.

This product has an average rupture coefficient of 767 MNm at 25°C.
, the density was 3.201 and the Weibull coefficient was 13.

The weight loss during preparation of this product was found to be 4.18%.

Furthermore, during the final sintering operation, it was found that with the 15R material, the silicon nitride was converted to the desired β monophase with a binary value of 0.5, and that the silicon nitride formed over 900 parts by weight of this final product; There was a slight amount of second phase containing .

As a modification of the 10th example, the final sintering process was carried out in the same manner as in the 10th example, but with a different ratio of microorganisms.

Note that silicon nitride and 15R products remain as before.

These results are summarized and shown in the following table.

It can be seen from the above table that the strength decreases as the ittria content approaches 100 parts by weight and the glass content becomes excessive.

In the eleventh example, 14.25 parts by weight of the 15R powder from the previous example was mixed with 85.75 parts by weight of the silicon nitride powder from the first example to form a first component, in which the atomic ratio was 0.75.
Further, 7 parts by weight of the ittria powder of Example 1 was added to this first component.

The sintering method of the first example is then repeated and the preform is
After maintaining the sintering temperature at 1840° C. for a period of time, the final product was prepared by cooling to room temperature.

This product has an average rupture coefficient of 810 MNm at 25°C.
, density 3.208 and the weight loss of this product is 2%
Met.

During the final sintering operation, it was found that the 15R material and silicon nitride were converted to the desired β' phase material with a binary value of 0.6, and that the silicon nitride comprised more than 90 volumes of the final product. be.

Transmission electron microscopy results show that the product contains more than 10 volumes of glass phase.

As a variation of Example 11, secondary isopress preforms of silicon nitride, 15R material and Ittria were subjected to the sintering process of Example 4.

As a result of the X-ray test, the obtained product was found to have 1.5 volumes of yttrium aluminum garnet, which is made by partial conversion of the glass product during sintering, and expands according to the above general formula with z = 0.6. This indicates that it contains more than 90 volumes of β-phase ceramic compound.

Average modulus of rupture at 25°C 534MNm”, density 3.2
It was 39.

In the twelfth example, 15R and the silicon nitride powder of the tenth example are again used, but in this case the 15R powder 15.75
Parts by weight are mixed with 84.25 parts by weight of silicon nitride powder to form a first component having the above atomic ratio of 0.752.

Adding 7 parts by weight of the aforementioned Ittria powder to this mixture;
Then, the treatment of Example 10 was performed.

After cooling to room temperature, it was removed from the protective atmosphere and the product was subjected to X-ray analysis.

As a result, it was found to contain more than 90 volumes of the β' product with z=0.7, along with a small amount of yttrium aluminum garnet, equivalent to just over 1 volume.

The density was 3.221, while the rupture modulus at room temperature was 630 MNm''.

A thirteenth example of the invention repeats the method of the twelfth example, but the first component consists of 82.75 parts by weight of silicon nitride and 1725 parts by weight of ground 15R material, the atomic ratio being 0.754.

Additionally, 7 parts by weight of ittria were added to the starting mixture.

X-ray analysis of the sintered product revealed an amount of yttrium aluminum garnet in an amount equivalent to over 1.5 volumes, an amount of yttrium silicon aluminum oxynitride in an amount equivalent to over 2 volumes, and β with z = 0.8. ' was found to contain more than 90 volumes of rice cake.

Fracture modulus at room temperature is 570MNm-2, density is 3.20
It was 0.

As a variation of Example 13, the final mixture preformed in Example 13 was sintered using the sintering method of Example 4, namely controlled cooling from the sintering stage.

The resulting product was cooled to room temperature and removed from the protective atmosphere, and X-ray analysis revealed an amount of yttrium aluminum garnet corresponding to well over 5.5 volumes and a β of 2=0.8.
' was found to contain more than 90 volumes of '.

Destruction coefficient at room temperature is 577 MNm”, density value is 3.23
It was 0.

Creep measurements of this product, measured at a load of 77 MN m'' and a temperature of 1227° C., show a creep of 0.1% in 8 hours, indicating the presence of zero glass phase.

In a fourteenth example of the invention, the method of the previous two examples is repeated, but the preform mixture contains 81.25 parts by weight of silicon nitride;
The ratio of the number of aluminum and silicon to the number of oxygen and nitrogen atoms in the first component, which contains 18.75 parts by weight of pulverized 15R and 7 parts by weight of ittria and is composed of silicon nitride and 15H, is 0.756.

As a result of X-ray analysis of the product obtained by the sintering method of the first example, it was found that it contained yttrium silicon aluminum oxynitride in an amount equivalent to 4 volumes and more than 90 volumes of β' with a binary value of 0.9. It is shown that.

The product had a rupture modulus of 520 MNm'' and a density of 3.188 at room temperature.

X-ray diffraction analysis of the product obtained as a variant of the fourth example shows the presence of 7 volumes of yttrium aluminum garnet and more than 90 volumes of β'.

The rupture coefficient of this product at room temperature is 543 MN m-2, the density is 3.179, while the load is 77 MN m'',
The creep measured at a temperature of 1227°C is 0.48 hours.
12%, indicating that there is less glass phase than in the previous example.

In the 45th example, the modification method of the 4th example is repeated, and the preform mixture is similar to the preform mixture of the previous example, but the first component is 79.75 parts by weight of silicon nitride and 20.25 parts by weight of crushed 15B material.
Based on parts by weight, the above atomic ratio is 0.758.

The results of X-ray diffraction analysis of the obtained product revealed that about 1 volume of yttrium silicon aluminum oxynitride, yttrium aluminum garnet in an amount equivalent to more than 8 volumes, and β' of z-=1 was 90. This indicates the presence of more than a large amount of capacity.

The modulus of rupture at room temperature is 500MNm'', the density is 3.22
It was 4.

The creep value at 1227℃ and load 77MNm-2 is 4.
0.023% after 8 hours, thus indicating that the glass content in this product is negligible.

In the 16th example, the previous method is repeated, but the first part of the mixture
Ingredients: 78.25 parts by weight of silicon nitride, crushed 15R21,
It consists of 75 parts by weight, and the above atomic ratio is 0.76.

Additionally, 7 parts by weight of Ittria were added to this mixture.

X-ray analysis of this product revealed the presence of 8.5 volumes of yttrium aluminum garnet, a small amount (approximately 1% by volume) of yttrium silicate, and more than 90 volumes of β' with a binary value of 21.1. It shows.

The rupture modulus at room temperature is 501 MNm'' and the density is 3.198, indicating that the product consists exclusively of ceramic phases.

The creep at 1227° C. and 77 MN m −2 was 0.019% after 48 hours.

The cases from the 13th to the 16th examples are modified sintering methods, but it should be noted that as the atomic ratio of 15R/silicon nitride increases, the glass phase gradually decreases, resulting in yttrium aluminum pomegranate. The stone is progressively increased and thus the high temperature properties of this product are improved.

Although the above example describes the use of yttria as the second component of the sintering mixture, similar results can be obtained using oxides of the metallic elements scandium, cerium, lanthanum and lanthanides.

Further, in the above example, the sintering process was performed without applying pressure, but it is also possible to apply pressure if necessary.

However, it should be noted that the strength, density and creep values obtained without pressing are comparable to those obtained with good hot pressed ceramics.

In these examples, the protective atmosphere for the sintering operation and subsequent heat treatment was done by embedding the samples in powdered boron nitride in a graphite crucible; I can do it.

Claims (1)

[Claims] 1. A method for manufacturing a ceramic product, comprising: forming a powder mixture comprising a first component and a second component, wherein the first component is silicon nitride, aluminum nitride, and alumina but does not contain added silica, and the ratio of silicon atoms to aluminum atoms to the total number of oxygen atoms and nitrogen atoms in the first component is 0.7.
35 to 0.77, and furthermore, the silicon nitride, aluminum nitride and alumina react with each other in the subsequent sintering step so that the silicon nitride, aluminum nitride and alumina react with each other in the general formula 8% and 1.5), and
The second component is an atom different from the atom, that is,
consisting of an oxide of at least one atom of yttrium, scandium, cerium, lanthanum and lanthanide metals, and in an amount between 0.1 and 10 wt. Sintering the mixture at a temperature between 1600° C. and 2000° C. for a period of at least 10 minutes up to at least 5 hours, under pressure or without pressure, in a protective atmosphere to sinter the monomer. A method for producing a ceramic article, characterized in that it comprises the step of producing a product containing at least 80 volumes of phase ceramic material and containing a second phase consisting of said at least one different atom. . 2 It has a crystal structure based on a hexagonal β single-phase silicon nitride lattice, but the dimensions of the unit cell are enlarged, and has the general formula % formula % (where 2 is from 0.38 to 1.5). 1. A method of manufacturing a ceramic article containing a single-phase silicon aluminum oxynitride according to the method (between) comprising: forming a powder mixture comprising a first component and a second component;
The first component is composed of silicon nitride and silicon aluminum oxynitride that does not follow the general formula, and these components are silicon nitride based on the total number of oxygen atoms and nitrogen atoms in the first component. The total number of atoms and aluminum atoms is in the range from 0.735 to 0.77, and the components react with each other in a subsequent sintering step to form a silicon aluminum oxynitride according to the general formula above. The second component is composed of an oxide of at least one atom of yttrium, scandium, cerium, lanthanum, and lanthanide metals, and in an amount between 0.1 and 10% by weight; furthermore, at a temperature between 1600°C and 2000°C for at least 10 minutes up to at least 5 hours, with the time decreasing as the temperature increases. sintering the mixture in a protective atmosphere under pressure or non-pressure for a period of time;
forming a product containing at least 80 volumes of said single phase silicon aluminum oxynitride and containing a second phase consisting of at least one different atom in said single phase silicon aluminum oxynitride. A method of manufacturing the ceramic product.