JP5188226B2 - Wear-resistant porcelain, sliding member and pump - Google Patents

Description

  The present invention relates to a wear-resistant ceramic, a sliding member, and a pump.

  Conventionally, alumina porcelain is used for seals, slide rings or pumps, pistons, and the like that require wear resistance.

  For example, Patent Document 1 describes that alumina porcelain is used as a radial or axial slide bearing in a centrifugal pump, a slide ring in a rotary mechanical seal, a piston or a piston casing for a reciprocating pump.

The alumina porcelain described in Patent Document 1 includes 1.2 to 6% by mass of Fe ₂ O ₃ , 0.1 to 0.3% by mass of MgO, 0.1 to 0.6% by mass of SiO ₂ , A molded product of sintered aluminum oxide containing 2.5% by mass or less of Mn ₃ O ₄ and 1.1% by mass or less of Cr ₂ O ₃ and the balance being 90 to 98% by mass of Al ₂ O _3. The average particle size of the crystalline component is 5 to 15 μm, and the proportion of the glass phase based on Fe ₂ O ₃ is ₂ to 10% by mass corresponding to the Al ₂ O ₃ content. .

  Moreover, as a porcelain composed of fine particles and coarse alumina, a mixture of coarse particles having a particle size of 0.2 to 5 mm mainly composed of corundum and fine particles having a particle size of 5 μm or less has a porosity of 0.1 to 20. An inorganic sintered ultra-precise measuring table that is adjusted to% and sintered at 1300 to 1500 ° C. and whose work surface is polished flat is known (see Patent Document 2).

Furthermore, 20 to 70% by mass of coarse-grained alumina having an average particle size of 30 to 200 μm, 20 to 70% by mass of fine-grained alumina having an average particle size of 1 to 5 μm, and zirconia particles having an average particle size of 5 to 30 μm A heat shock-resistant alumina characterized by mixing 5 to 30% by mass to form a molded body, firing the molded body, and finely dispersing zirconia particles in alumina that binds coarse alumina. -The manufacturing method of the jig | tool for a zirconia quality baking is known (refer patent document 3).
Japanese Patent No. 3431179 Japanese Patent Publication No. 3-31664 Japanese Patent No. 3949950

  In the alumina porcelain described in Patent Document 1, although the corrosion resistance to the aqueous solution is improved, a porcelain having an average particle diameter after sintering of about 8 μm is obtained using an alumina raw material of 1 to 2.5 μm. The porcelain has a problem that there are few large-diameter alumina particles and wear resistance is low.

  Moreover, in the alumina porcelain described in Patent Document 2, the alumina particles are too large, and a large number of pores exist between the alumina particles, the strength is low, and there is a risk of breakage when used as a shaft or a bearing. there were.

  Furthermore, the alumina / zirconia firing jig described in Patent Document 3 contains moderate pores, and an open porosity of 0.1% or less cannot be obtained, and the bending strength is 33 to 68 MPa. There was a problem of being small.

  An object of the present invention is to provide a wear-resistant ceramic, a sliding member, and a pump that are dense and can improve wear resistance.

  As a result of studying the above problems, the present inventors have, as alumina crystal particles constituting the porcelain, large alumina particles having a particle size of 10 μm or more and small alumina particles having a particle size of 5 μm or less, and on the surface of the porcelain. By setting the area ratio of the alumina large-diameter particles to 35 to 65% and the open porosity to 0.1% or less, the porcelain surface having a dense and constant strength and having a large number of alumina large-diameter particles can be obtained. Since the ceramic member slides, the inventors have found that the amount of wear can be reduced and have reached the present invention.

That is, the wear-resistant porcelain of the present invention is a wear-resistant porcelain substantially composed of alumina crystal particles and a grain boundary phase, and has an open porosity of 0.1% or less. , a large particle size 10μm or more alumina-sized particles, containing the following alumina small particles with particle sizes of 5 [mu] m, the area ratio of the alumina large particles in the ceramic surface Ri 35% to 65% der, of the alumina small particles The area ratio is 15 to 40%, and the three-point bending strength is 260 MPa or more and 380.
And wherein the Der Rukoto following MPa.

  In such wear-resistant porcelain, the area ratio of alumina large-diameter particles having a particle diameter of 10 μm or more on the porcelain surface is 35 to 65%. For example, even when a ceramic member slides on the porcelain surface. The ceramic member slides on the surface of the alumina large-diameter particles, and wear can be suppressed. In addition, the wear-resistant porcelain of the present invention has an open porosity of 0.1% or less, and thus becomes dense and can improve strength.

  Moreover, the wear-resistant ceramic of the present invention is characterized in that the area ratio of the alumina small-diameter particles on the surface of the ceramic is 15 to 40%. In such wear-resistant ceramics, the area ratio of small alumina particles having a particle diameter of 5 μm or less is as large as 15 to 40%, so that the strength of the wear-resistant ceramics can be increased.

Further, the wear-resistant porcelain of the present invention is characterized in that Al is contained in the porcelain in an amount of 90 to 98% by mass in terms of Al ₂ O ₃ . In general, when Al is contained in an amount of 90 to 98% by mass in terms of Al ₂ O ₃ , the binodal structure containing an alumina large particle having a particle diameter of 10 μm or more and an alumina small particle having a particle diameter of 5 μm or less Since it becomes difficult to become, this invention can be used suitably.

In addition, the wear-resistant porcelain of the present invention is characterized in that Si is contained in the porcelain in an amount of 1% by mass or less in terms of SiO ₂ . In such wear-resistant porcelain, the grinding resistance is slightly increased by containing a predetermined amount of Si, but the strength is improved. For example, sufficient strength is obtained even when used for a cylindrical shaft having a small diameter. And the long-term reliability of the pump can be improved. The porcelain may contain substantially no Si, in other words, as an impurity. In such wear-resistant porcelain, since the porcelain is substantially free of Si, the bonding force between the alumina crystal particles is not so high, thereby reducing the machining of the porcelain, especially the grinding resistance. And processability can be improved.

The wear-resistant ceramic of the present invention is characterized in that the ceramic contains Mn and Ti, and the Mn and Ti are present as MnTiO ₃ based crystals. In such wear-resistant porcelain, it is easy to produce a glass containing Mn, Ti, and Si present as an impurity in the porcelain, but because Mn and Ti in the porcelain exist as MnTiO ₃ -based crystals, The generation of glass in the porcelain is suppressed, and the free cutting property can be improved.

  The sliding member of the present invention is characterized in that at least the sliding surface is formed of the wear-resistant ceramic. In such a sliding member, since the open porosity is 0.1% or less, it is dense and high in strength, and the ceramic member slides on the surface of the alumina large-diameter particles, so that wear Can be suppressed.

  The pump of the present invention is a pump having a shaft and a bearing, wherein at least one of the shaft and the bearing is made of the sliding member. Since the shaft and bearing have an open porosity of 0.1% or less, they are dense and strong, and the shaft is inserted through the bearing.For example, large-diameter alumina particles on the outer surface of the shaft hit the inner surface of the bearing. Since they come into contact with each other and slide, wear of the shaft can be suppressed and durability can be improved. Furthermore, by adopting a configuration that substantially does not contain Si in the grain boundary phase, it is possible to reduce the resistance when grinding the shaft and the bearing, and to improve workability.

  In the wear-resistant porcelain of the present invention, the area ratio of alumina large-diameter particles having a particle diameter of 10 μm or more on the porcelain surface is 35 to 65%. For example, even when a ceramic member slides on the porcelain surface. The ceramic member slides on the surface of the alumina large-diameter particles, so that the wear can be suppressed and the open porosity is 0.1% or less, so that it is dense and the strength can be improved.

  In the sliding member of the present invention, since the open porosity is 0.1% or less, it is dense and high in strength, and since the ceramic member slides on the surface of the alumina large-diameter particles, wear Can be suppressed.

  In the pump of the present invention, since the shaft and the bearing have an open porosity of 0.1% or less, the pump is dense and high in strength, and the shaft is inserted through the bearing. For example, the alumina large-diameter particles on the outer surface of the shaft Since it comes into contact with and slides on the inner surface of the bearing, the wear of the shaft can be suppressed and the durability can be improved.

The present invention is described in detail below. In the wear-resistant porcelain of the present invention, the open porosity is 0.1% or less, and substantially consists of alumina crystal particles and a grain boundary phase. As shown in FIG. a particle size 10μm or more alumina larger particles 1, containing the following alumina small particle 3 particle size 5 [mu] m, the area ratio of alumina large particles 1 in the porcelain surface Ri 35% to 65% der, alumina small particles area ratio is 15 to 40%, 3-point bending strength, characterized in der Rukoto least 380MPa or less 260 MPa.

In the wear-resistant porcelain of the present invention, it is desirable to comprise 90 to 98% by mass of alumina and 2 to 10% by mass of the grain boundary phase. That is, it is desirable to contain Al in the porcelain in an amount of 90 to 98% by mass in terms of Al ₂ O ₃ . In general, when Al is contained in an amount of 90 to 98% by mass in terms of Al ₂ O ₃ , the binodal structure containing an alumina large particle having a particle diameter of 10 μm or more and an alumina small particle having a particle diameter of 5 μm or less less likely, but the present invention, the reason is not clear, even when it contains 90 to 98 wt% in the total amount of Al in terms of Al ₂ O _3, it can be binodal tissue. In addition, although mentioned later, crystals other than alumina may precipitate a little.

  Here, in the present invention, the particle size refers to the area of the alumina crystal particles formed by forming a porcelain surface on which the shape of each crystal particle can be confirmed by thermal etching after mirror-processing the porcelain cross section, and analyzing the micrograph image. This is the diameter when calculated and obtained from this area on the assumption that the cross section of the particle is circular. The porcelain surface of the present invention is a ground surface.

  In FIG. 1, alumina particles having a particle diameter of 5 to 10 μm intermediate between the large alumina particles 1 and the small alumina particles 3 are also present. The alumina large particle 1 preferably has a particle size of 10 to 50 μm. This is because when the alumina large-diameter particles 1 are larger than 50 μm, it becomes difficult to sinter and it is difficult to achieve an open porosity of 0.1% or less. Further, it is desirable that the small alumina particles 3 have a particle size of 5 μm or less, more preferably 3 μm or less. This is because a size smaller than 3 μm sinters at a lower temperature and easily forms a binodal structure.

  In the wear-resistant ceramic of the present invention, it is important that the area ratio of the alumina large-diameter particles 1 on the ceramic surface is 35 to 65%. In such wear-resistant porcelain, by setting the area ratio of the alumina large-diameter particles 1 on the porcelain surface to 35 to 65%, even if the ceramic member slides on the porcelain surface, the ceramic member Abrasion can be suppressed by sliding on the surface of the large alumina particles. The reason why the area ratio of the alumina large-diameter particles 1 is 35 to 65% is that when the amount is less than 35%, the amount of wear increases, and when the amount is more than 65%, the sinterability decreases and open pores. This is because it becomes difficult to achieve the rate of 0.1% or less, and the strength decreases. It is desirable that the area ratio of the alumina large-diameter particles 1 on the surface of the porcelain is 40 to 60% from the viewpoint of reducing the wear amount and improving the porcelain strength.

On the other hand, when the area ratio of the small alumina particles on the surface of the porcelain is 15 to 40% , a finer porcelain can be obtained even if large particles exist. The area ratio of the alumina small-diameter particles is preferably 20 to 40% from the viewpoint of obtaining a dense body.

  In such an abrasion-resistant ceramic, as will be described later, for example, when the ceramic member slides on the surface of the ceramic, the alumina large-diameter particles 1 sufficiently receive the pressing force of the ceramic member, and the alumina small-diameter particles 3 It is possible to suppress degranulation and improve wear resistance.

  In the present invention, a large feature is that the open porosity is 0.1% or less. Since the open porosity is 0.1% or less, it can be made dense, and thereby high strength can be achieved.

  In the wear-resistant ceramic of the present invention, the area ratio of the small alumina particles 3 on the surface of the ceramic is preferably 15 to 40%. As a result, a dense surface can be obtained, the resistance during sliding can be reduced, and the strength of the wear-resistant ceramic can be increased. In particular, the content is preferably 25 to 35%.

Furthermore, in the wear-resistant porcelain of the present invention, Si is contained in the porcelain in an amount of 1% by mass or less in terms of SiO ₂ . In this case, it means that Si is added, and the total amount of Si present as an impurity and added Si is 1% by mass or less in the total amount in terms of SiO ₂ . In such a wear-resistant ceramic, by containing less than 1 wt% of S i in terms of SiO _2, although the grinding resistance is slightly higher, strength is improved, for example, a cylindrical shaft pump a smaller diameter When used, sufficient strength can be obtained and the long-term reliability of the pump can be improved.

On the other hand, in the wear-resistant porcelain of the present invention, there is a case where Si is not substantially contained in the porcelain, that is, it is contained only as an impurity. In such wear-resistant porcelain, since the porcelain is substantially free of Si, the bonding force between the alumina crystal particles is not so high, thereby reducing the machining of the porcelain, especially the grinding resistance. And processability can be improved. The fact that Si is not substantially contained in the porcelain means that Si is not positively added as a grain boundary phase forming component, and means that Si is contained in an amount of 0.46% by mass or less in terms of SiO _2. .

As the grain boundary phase constituent elements, there are Mn and Ti in addition to the Si, and at least one of Ba, Ca, Sr and Mg. Precipitation of crystals such as MnTiO ₃ , MnAl ₂ O ₄ , (Ba, Ca, Sr, Mg) Mn _1.75 AlO ₄ may be confirmed at the grain boundaries of the alumina crystal. _When a liquid phase (glass) containing Si, Mn, and Ti is formed under the influence of ₂ O ₃ and SiO ₂ contained as an impurity, the bonding strength between Al ₂ O ₃ particles increases and the porcelain strength improves. On the other hand, the grinding resistance increases.

However, when the added Mn and Ti are present as MnTiO ₃ based crystals, the generation of glass containing Si, Mn, and Ti is suppressed, and the free-cutting property can be improved. Note that the sense of the MnTiO ₃ based crystal, MnTiO ₃ not crystal only, Mn, part of Ti is, other elements such as a part of Mn is Ba, Ca, even if it is substituted with Sr and Mg containing It is.

  The wear-resistant porcelain of the present invention has an average particle size of 2-5 μm on the porcelain surface.

  Such wear-resistant porcelain is formed by adding alumina coarse powder having an average particle diameter of 10 μm or more, alumina fine powder having an average particle diameter of 3 μm or less, and a grain boundary phase forming material, mixing them, and then forming into a predetermined shape. It is obtained by firing at 1200 to 1500 ° C. for 1 to 3 hours in an oxidizing atmosphere.

  As the alumina coarse powder, a commercially available alumina coarse powder having an alumina content of 99% or more and an average particle size of 25 to 40 μm can be used. As the alumina fine powder, an alumina content of 99% or more and an average particle size of 1.8 to Commercially available low soda alumina powder of 3 μm can be used.

  Grain boundary phase forming materials include Si, Mn, Ti, Ba, Sr, Ca, Mg oxides, carbonates, hydroxides, and compounds that form oxides by firing such as complex oxidation containing these elements The fine powder can be used.

  The raw material powder may be mixed by a dry method, but when mixed by a wet method, it is granulated and molded by spray drying or the like.

  In addition, in the case of mixing and pulverizing with a ball mill or the like, calcium oxide, chromium oxide, cobalt oxide, magnesium oxide, silica, manganese oxide, iron oxide may be mixed from water or balls as solvents to be used. If it is within the range that satisfies the above, there is no problem.

  In the wear-resistant porcelain as described above, the area ratio of alumina large-diameter particles having a particle diameter of 10 μm or more on the porcelain surface is 35 to 65%. For example, this is a case where a ceramic member slides on the porcelain surface. In addition, the ceramic member slides on the surface of the alumina large-diameter particles, and wear can be suppressed. In addition, the wear-resistant porcelain of the present invention has an open porosity of 0.1% or less, and thus becomes dense and can improve strength.

  In the sliding member of the present invention, at least the sliding surface is made of the above wear-resistant porcelain, and the surface on which the ceramic member slides is a porcelain surface. Sliding members include, for example, radial or axial friction bearings, sliding rings in rotary mechanical seals, pistons or piston casings for reciprocating pumps, adjustment / control liquid flow (eg, in valves and fittings) or gas in low power motors There are sealing and control disks for flow (e.g. fans), linings for containers and ducts, in the mill, or guide members such as screw guides. In the sliding member of the present invention, at least the sliding surface may be made of the above wear-resistant ceramic, and the entire sliding member may be made of the wear-resistant ceramic of the present invention.

  In such a sliding member, since the open porosity is 0.1% or less, it is dense and high in strength, and the ceramic member slides on the surface of the alumina large-diameter particles, so that wear Can be suppressed.

  The pump of the present invention includes a shaft and a bearing, and at least one of the shaft and the bearing is made of the sliding member. For example, there is a pump in which the shaft passes through a ring-shaped bearing. In such a pump, the shaft and the bearing have an open porosity of 0.1% or less, so that they are dense and high in strength, and the alumina large-diameter particles on the outer surface of the shaft are in contact with and slide on the inner surface of the bearing. Therefore, wear of the shaft can be suppressed, and durability can be improved.

As the alumina coarse powder, a commercially available alumina powder having an alumina content of 99.6% and an average particle diameter of 25 to 80 μm was used. As the alumina fine powder, an alumina content of 99.8% and an average particle diameter of 1.8 to 3 μm was used. Commercially available low soda alumina powder was used. Further, _MnO 2 having an average particle size of 1μm measured by a laser scattering _method, CaCO 3, SrCO _3, average particle size 3.5μm of MgCO _3, were used TiO ₂ powder 0.5μm as auxiliaries.

As a system in which SiO ₂ is mixed, MnO ₂ and TiO ₂ as auxiliary components and MgCO ₃ , CaCO ₃ and SrCO ₃ as alkaline earth carbonates have a mass ratio of MnO ₂ : TiO ₂ : alkali in terms of oxides. The earth oxide was measured to be 3: 2: 1, and water and 93% purity alumina balls were put into an alumina pot and ground for 100 hours.

In order to avoid mixing of SiO ₂ , weighed MnO ₂ : TiO ₂ : MgO (using MgCO ₃ ) = 3: 2: 1, put water and 99.9% purity alumina balls into the resin mill, Milled for 100 hours.

Alumina coarse powder, alumina fine powder and an auxiliary agent were added so that the weight ratio shown in Table 1 was obtained, and further 4% of water and a known binder were added and mixed with a hand mixer to obtain a slurry. The slurry was dried using a spray dryer to form granules, which were pressure-molded at a pressure of 1 t / cm ² and fired at 1370 ° C. in the atmosphere.

  The porcelain obtained was measured for open porosity by the Archimedes method and listed in Table 2.

  Further, the surface of the obtained porcelain after being mirror-finished and thermally etched at 1200 ° C., using a metal microscope and an image analyzer, the area ratio of large alumina particles having a particle size of 10 μm or more, and small alumina particles having a particle size of 5 μm or less The area ratio% was measured. The area ratio was measured in an area of 200 μm × 150 μm from a 400 × metal micrograph and listed in Table 2. Similarly, the average particle size was determined. As a result, the average particle size of the sample of the present invention was 2 to 5 μm.

  Further, as shown in FIG. 2A, the grinding resistance was set on a surface grinder equipped with a dynamometer, a sample having a shape of 7 mm × 100 mm and a thickness of 20 mm, and the grinding stone was SDC140N7SBA (Asahi Diamond). Cutting conditions: flange cut (both ends cutting), grinding wheel rotation speed: 1800 rpm, grinding wheel peripheral speed: 1720 m / min, bed feed speed: 20 m / min, cutting amount: 0.03 mm / pass, normal direction The grinding resistance per 1 mm sample width was calculated and listed in Table 2.

  Further, as shown in FIG. 2 (b), the wear characteristics were measured using a disk-shaped ceramic having a diameter of 25 mm and a thickness of 5 mm and a disk-shaped ceramic having a diameter of 10 mm and a thickness of 3 mm. The wear characteristics were 10 mm in diameter and 3 mm thick disk-shaped porcelain rotating on the outer periphery of a 25 mm diameter and 5 mm thick disk-shaped porcelain with a friction radius of 9 mm at 500 gf. The width and depth of wear marks on the surface of a disk-shaped porcelain having a diameter of 25 mm and a thickness of 5 mm were measured using a surface roughness meter. Table 2 shows the wear evaluation results obtained by multiplying the measured width and depth of the wear marks.

Further, the three-point bending strength was measured based on JIS R 1601 and listed in Table 2. Further, emission spectroscopy porcelain and (ICP), to measure the amount of Si has been described with SiO ₂ in terms of Table 2. Moreover, when the amount of Al was measured, the sample of the present invention contained 90 to 98% by mass in the total amount in terms of Al ₂ O ₃ . Further, the crystal phase was identified by X-ray diffraction measurement, and the presence or absence of MnTiO ₃ -based crystals was determined and listed in Table 1. In FIG. 6 shows the X-ray diffraction of 6;

According to Tables 1 and 2, and a particle size 10μm or more alumina larger particles, as well as containing the following alumina small particles with particle sizes of 5 [mu] m, the area ratio of alumina large particles is 35 to 65% alumina diameter and 15 to 40 percent area ratio of particles in the sample of the present invention the open porosity is 0.1% or less, because an open porosity of 0.1% or less, it becomes dense, the intensity 2 6 It can be determined that the wear evaluation test is as small as 1835 (μm) ² or less because the area ratio of the alumina large-diameter particles is 35 to 65%.

Moreover, by reducing the a SiO ₂ content of 0.46 wt% or less, the grinding resistance is seen that the smaller than 38N / m.

  On the other hand, sample No. of the comparative example with many large alumina particles. In Sample No. 1, the open porosity was as large as 0.2% and the alumina raw material particle size was as large as 80 μm. 9 shows that the open porosity is as large as 0.35% and the strength is low. Sample No. of Comparative Example with few large alumina particles. 5 shows that the amount of wear increases.

  Furthermore, sample No. using only fine powder raw material of alumina. 10, it can be seen that there are no large alumina particles having a particle size of 10 μm or more, and the amount of wear is large.

Furthermore, sample No. 1 having a Si content of 1% by mass in terms of SiO ₂ was obtained. No. 16 shows the case where 0.7% by mass of SiO ₂ powder is added, but the grinding resistance increases, but the strength increases and the wear resistance is good.

1 shows the surface of a wear-resistant ceramic according to the present invention. The evaluation method of the wear-resistant porcelain of this invention is shown, (a) is explanatory drawing of a grinding resistance test, (b) is explanatory drawing of a wear evaluation test. Sample No. 6 is an x-ray diffraction diagram of FIG.

Explanation of symbols

1: Alumina large particle 3: Alumina small particle

Claims (6)

A wear-resistant porcelain substantially composed of alumina crystal particles and a grain boundary phase, having an open porosity of 0.1% or less, and the alumina crystal particles include alumina large-diameter particles having a particle size of 10 μm or more and contains a particle size 5μm or less of the alumina small particles, the area ratio of the alumina large particles in the ceramic surface Ri 35% to 65% der area ratio of the alumina small particles is 15 to 40%, 3 abrasion-resistant porcelain point flexural strength, characterized in der Rukoto least 380MPa or less 260 MPa. Abrasion-resistant ceramic of claim 1, characterized in that it contains 90 to 98 wt% in the total amount of Al in terms _{of Al} 2 _{O 3} in the ceramic. Abrasion-resistant ceramic of claim 1 or claim 2, characterized in that it contains less than 1 wt% in the total amount of Si in terms of SiO ₂ in the porcelain. The wear-resistant porcelain according to claim 3 , wherein the porcelain contains Mn and Ti, and the Mn and Ti are present as MnTiO ₃ based crystals. A sliding member characterized in that at least the sliding surface is formed of the wear-resistant ceramic according to any one of claims 1 to 4 . A pump comprising a shaft and a bearing, wherein at least one of the shaft and the bearing comprises the sliding member according to claim 5 .