JPH0373310A - Production of ceramic sintered body - Google Patents

Abstract

PURPOSE:To uniform density of a green molded form and to enhance dimensional precision and to lower generation of a crack and to greatly reduce the manufacturing cost by uniaxially pressurizing powder of a ceramic raw material to form the green molded form and thereafter pressure-molding it by wet cold hydrostatic pressing treatment. CONSTITUTION:The pressing faces 3a, 3b of the upper and lower punches 4, 5 are formed in coincidence with the shapes of the upper and lower sides of a sintered body to be formed. A green molded form 1c is obtained by pressing the upper and lower punches 4, 5 at prescribed pressure and uniaxially pressurizing powder 7 of a ceramics raw material. Then this green molded form 1c is introduced into a housing bag 9 which has flexibility and is made of synthetic resin. Such material may be utilized for the housing bag 9 that it is closely stuck to the whole surface of the green molded form 1c and does not permeate water and has flexibility. A housing bag 10 formed into two layers by nylon and PE is desirably utilized from a point wherein toughness is made especially great and excellent in watertightness and inexpensive and capable of heat sealing. This two-layer bag 10 is immersed in a cold hydrostatic pressing device and water utilized as a pressure medium is pressurized at prescribed pressure P. The green molded form 1c isotropically receives hydrostatic pressure P in the whole surface via the film of the two-layer bag 10 and is pressurized in the central direction.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Field of Application) The present invention relates to a method for manufacturing a ceramic sintered body, and in particular, to prevent cracking in the manufacturing process even when the sintered body has a complicated shape. The present invention relates to a method for producing a ceramic sintered body that has low generation, high dimensional accuracy and high raw material yield, and is capable of producing the ceramic sintered body at low cost and efficiency, and has excellent mass productivity.

(Conventional technology) Ceramics such as silicon nitride and silicon carbide have high hardness, superior properties such as wear resistance, high temperature strength, and corrosion resistance compared to conventional metal materials, and also have a density of about 3g
Due to its light weight of /cil, it has been developed for a wide range of applications and is mass-produced as a precision parts material for automobiles, aircraft, chemical and electrical equipment, etc.

However, since the ceramic sintered body has extremely high hardness, it is extremely difficult to grind and polish it to the final product size.

Therefore, conventional sintered bodies have generally been used in simple shapes such as flat plate shapes or ring shapes.

In other words, sintered bodies of simple shapes, in which both the upper and lower surfaces of the product are flat and have no undulations such as steps or curved surfaces, have become mainstream.

These sintered bodies are made by uniaxially pressing raw material powder,
It is formed by degreasing and sintering the resulting green body. The pressing surfaces of the upper and lower punches of the uniaxial pressure press used here are both formed flat.

Therefore, the axial dimension of the formed body is constant, and there is no density difference in each part of the formed body. Therefore, a sintered body having a uniform strength distribution can be obtained.

However, the development of applications for ceramic sintered bodies has progressed further since then, and ceramic sintered bodies having more complicated shapes have come to be manufactured. For example, as shown in FIG. 8(a), a spherical sintered body 100 as a bearing ball
A rod-shaped sintered body 200 with curved surfaces at both ends as shown in FIG. 8(b), and a rod-shaped sintered body 200 with a spherical top surface shape as shown in FIG. 8(c) are used as valve opening/closing members for internal combustion engines. On the other hand, there are various types of sintered bodies with complicated shapes, such as a rivet-like sintered body 300 whose lower surface is cylindrical in shape, and a sintered body 400 with protrusions formed with a step on its upper surface as shown in FIG. 8(d). Ceramic sintered bodies are used as components of automobiles, home appliances, and medical equipment.

Among these ceramic sintered bodies, a conventional manufacturing method will be described below, taking as an example a spherical ceramic sintered body used as a bearing ball.

This spherical ceramic sintered body is generally made of Figs.
Manufactured by the manufacturing process shown in d).

That is, first, a ceramic raw material powder is uniaxially compressed and solidified using a mold press or the like to form a cylindrical shaped product 1 as shown in FIG. 9(a).

Next, the upper and lower edges of the obtained cylindrical generated body 1 are chamfered into a straight line or a curved line, respectively, as shown in FIG. 9 (b).
) or to form nearly spherical shaped bodies 1a, lb as shown in FIG. 9(C).

After degreasing and sintering, the resulting formed bodies 1a and lb are surface-treated by lapping, polishing, etc.
Adjustments are made to obtain predetermined sphericity, diameter irregularity, surface roughness, and mutual difference, and finally a ceramic sphere 2 having high dimensional accuracy as shown in FIG. 9(d) is manufactured.

By the way, the shape accuracy of the ceramic sphere 2 used for the bearing ball is specified by grade according to JIS B-1501 etc. in order to guarantee the rotational accuracy of the bearing. For example, the 10th grade (GIO) bearing ball The standard value for the difference in diameter is 0.25 .mu.m.

As described above, the finished dimensions of the ceramic sphere 2, which is the final product, are extremely strict, and sophisticated dimensional control is carried out from the molding stage to sintering and polishing. This has the disadvantage that the manufacturing process becomes complicated and the processing cost increases significantly.

In particular, sintered ceramics such as silicon nitride are substances with high covalent bonding properties, have extremely high hardness, and are extremely difficult to polish. Incidentally, when compared with conventional metal spheres, ceramic spheres have the disadvantage of requiring processing costs that are several tens to hundreds of times higher.

Furthermore, as shown in FIG. 9(a), the upper and lower edges of the cylindrical shaped body 1 are scraped off to form the nearly spherical shaped bodies 1a and lb, so that a small amount of high-purity and expensive ceramic raw material powder can be used. There is also the problem that the dripping rate is low and the economical efficiency is reduced.

Therefore, it is important to pre-finish the soft formed body into a shape as close to the product dimensions as possible before sintering, or to perform so-called near-net forming, to reduce processing man-hours and waste of raw materials for these types of ceramic parts. This is an important point in reducing

Therefore, as shown in FIG. 1, a mold press is installed in which an upper bunch 4 and a lower bunch 5, each having a hemispherical pressing surface 3a, 3b corresponding to the radius of the product, are fitted into a die 6 from above and below. Attempts have also been made to use a machine to fill and press ceramic raw material powder 7 between upper and lower punches 4.5 to form a nearly spherical shaped body IC as shown in FIG. 2 all at once.

A band-shaped columnar portion 8 is formed at the central equatorial portion of the generated body 1c. This cylindrical part 8 is formed by the upper and lower punches 4 during compression molding.
, 5 are formed because it is impossible to press them until they come into close contact with each other.

According to the molding operation using the above mold press machine, it is possible to form a nearly spherical shaped body 1c as shown in FIG. can be improved and economical efficiency can be improved.

(Problem to be Solved by the Invention) However, as in the conventional method for manufacturing a ceramic sintered body as described above, a mold press machine is used to press the ceramic raw material powder 7 only in one axis direction to form a curved surface. In the method of forming a green body, the axial distance at each curved surface position is different, so that the density inside the green body IC becomes non-uniform, resulting in a decrease in dimensional accuracy and the occurrence of cracks. Especially for the band-shaped columnar part 8 with high density,
The density of the upper and lower hemispherical parts R tends to decrease, and as shown in FIG. 10, cracks 18 tend to occur at the boundary between the cylindrical part 8 and the hemispherical part R, resulting in lower product yields and lower manufacturing costs. There was a downside to rising.

On the other hand, injection molding has recently been adopted as a near-net molding method for ceramics. However, molded bodies formed by injection molding require a long time to degrease, which reduces manufacturing efficiency.In addition, the yield of products is lower than that of press molded products, and it is not a stable molding method. In any case, there was a problem that mass production was inferior.

The present invention was made to solve the above problems, and it is possible to make the density of the formed body uniform and improve the dimensional accuracy, reducing the occurrence of cracks and significantly reducing manufacturing costs. The purpose of the present invention is to provide a method for manufacturing a ceramic sintered body that can be manufactured using the following methods.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above object, the method for manufacturing a ceramic sintered body according to the present invention provides a pressing surface that matches the top and bottom shapes of the sintered body to be formed. After the ceramic raw material powder is uniaxially pressed by the upper punch and lower punch formed to form a green body, the green body is pressure-molded by a wet cold open isostatic press treatment, and then the resulting green body is degreased. It is characterized by performing final surface processing after sintering.

In addition, in the wet cold isostatic pressing process, the formed body is housed in a flexible synthetic resin storage bag, and the inlet opening of the storage bag is heat-sealed while the pressure inside the bag is maintained below atmospheric pressure. After the storage bag is sealed, the sealed storage bag is immersed in water and isostatically compressed by applying hydrostatic pressure.

(Function) According to the method for producing a ceramic sintered body having the above configuration, the formed body formed by uniaxially pressing the ceramic raw material powder is further pressure-molded by a wet cold isostatic pressing method. The entire surface of the feature is compressed evenly towards the center by hydrostatic pressure. As a result, the resulting body becomes more dense and its density is uniform throughout. Therefore, there is little reduction in dimensional accuracy, and less cracking occurs during the molding and sintering stages, making it possible to improve product yield.

In addition, the formed body is obtained by compression molding the raw ceramic powder using upper and lower punches whose pressing surfaces are respectively formed to match the upper and lower shapes of the sintered body to be formed. A so-called near-soto formed shape, which is close to the shape, can be obtained.

Therefore, compared to the conventional method of cutting and molding from a cylindrical shaped body, it is possible to significantly improve the yield of the product based on the raw material powder, and it also has the effect of facilitating the polishing work after sintering. This makes it possible to significantly reduce the manufacturing cost of ceramic sintered bodies with complex shapes.

In addition, the generated body is stored in a flexible synthetic resin storage bag, and the entrance opening of the storage bag is sealed by heat sealing, and then the sealed storage bag is immersed in water to apply hydrostatic pressure. By adopting a wet cold isostatic press process, a conventional cold isostatic press typically uses a thick rubber bag as a storage bag and firmly fastens the inlet opening of the rubber bag with a fastener. The sealing process is extremely easy compared to the process, and the work cost can be significantly reduced.

(Example) Next, an example of the present invention will be described with reference to the accompanying drawings. 1 to 4 are diagrams showing each step of manufacturing a ceramic sphere as shown in FIG. 9(d) using the method for manufacturing a ceramic sintered body according to the present invention.

That is, in the method for manufacturing a ceramic sintered body according to this embodiment, first, as shown in FIG. Using a mold press machine in which punches 4 and 5 are fitted into a die 6 so as to be able to move up and down, ceramic raw material powder 7 is filled between the upper and lower punches 4 and 5.

Next, the ceramic raw material powder 7 is uniaxially pressed by pressing the upper and lower punches 4 and 5 with a predetermined pressure to obtain a formed body 1C as shown in FIG.

Here, the generated body 1c has a band-shaped cylindrical part 8 in the central equatorial region, and hemispherical parts R, R formed by upper and lower punches 4.5 at the upper and lower parts thereof, respectively. This width of the cylindrical portion 8 occurs because the upper and lower punches 4 and 5 cannot be brought into perfect contact with each other, and should be made as small as possible in order to make the polishing work in the subsequent process easier. desirable.

However, in consideration of the degree of compression by the upper and lower punches 4 and 5, the ratio b/a of the width to the diameter a of the formed shape is preferably set to 0°3 or less. This is because if the value exceeds 0.3, the amount of polishing required for the sintered body in the final finishing step increases rapidly, and the number of polishing steps increases.

Next, the obtained green body 1C is pressure-molded by wet cold isostatic pressing (CIP) according to the procedure shown in FIGS. 3(a) to 3(C).

That is, as a preparatory work, first, as shown in FIG. 3(a), a nylon-polyethylene double-layer bag 10 is prepared as a storage bag 9 made of flexible synthetic resin, and the inside of this nylon-polyethylene double-layer bag 10 is The generated body 1c is put into the container.

Here, the storage bag 9 may be made of any material that is in close contact with the entire surface of the formed body 1c, does not allow water to pass through, and has flexibility.
In particular, a storage bag made of two pieces of nylon and polyethylene is desirable because it has high toughness, excellent watertightness, is inexpensive, and can be heat-sealed. In particular, a two-layer storage bag with an inner layer made of nylon, which has a relatively low melting point, and an outer layer made of polyethylene, which has a higher melting point than nylon, has excellent sealing properties.

Next, in order to prevent water from entering the nylon-polyethylene double-layer bag 10 into which the formed body 1C is placed, the entrance of the nylon-polyethylene double-layer bag 10 is closed as shown in FIG. 3(b). A heat seal line 11 is formed and sealed by a so-called heat seal method in which the wires are heated and fused.

The heating temperature during heat sealing is preferably set to an intermediate temperature between the melting point of nylon and the melting point of polyethylene. By setting this temperature, only the inner layer made of nylon melts at the sealing portion, and the storage bag 9 can be effectively sealed.

If a large amount of air remains inside the storage bag 9 at this time, the remaining air will be pressurized during the wet cold isostatic pressing process, and there is a high possibility that the storage bag 9 will be damaged by the generated high-pressure air. Therefore, it is desirable that the pressure inside the storage bag 9 during heat sealing is as low as possible, but after storing the formed body 1c in the storage bag 9, the storage bag 9 is lightly pressed to eliminate the gas inside, and the It is sufficient that the pressure inside the bag 9 is below atmospheric pressure.

Then, as shown in FIG. 3(C), the sealed nylon-polyethylene double layer bag 10 is placed in a cold isostatic press machine (CI).
P) and pressurizes water as a pressurizing medium to a predetermined pressure P. The formed body 1c is subjected to hydrostatic pressure P in the same direction on its entire surface through the membrane of the nylon-polyethylene double-layer bag 10, and is pressurized toward the center. As a result, the generated form IC
becomes more compact and its density becomes uniform throughout.

In addition, pressurized water is blocked by the nylon-polyethylene double layer bag 10, thereby preventing quality deterioration due to pressurizing water entering the inside of the formed body IC.

When the cold isostatic pressing process is completed, the resulting formed IC is taken out together with the nylon-polyethylene double layer bag 10. The nylon-polyethylene double layer bag JO is then torn open and the formed body IC is taken out from inside.

The removed formed body IC is subjected to a degreasing and sintering process to form a sintered body 15, and then subjected to a barrel polishing machine fi shown in FIG.
The surface is roughly processed by lll12.

Here, the barrel polishing device 12 includes, for example, a metal bond polishing grindstone 14 attached to the upper surface of a substrate 13 rotating on a horizontal plane.
, a cylindrical device main body 16 that accommodates a sintered body 15 obtained by sintering the formed body IC, and a cover 17 that closes the upper part of the device main body 16.

By rolling on the rotating metal bond polishing grindstone 14, the sintered body 15 is polished by scraping off the band-shaped cylindrical portion 8 shown in FIG. The sintered body 15 obtained in this way is further subjected to final surface processing by lapping and polishing to achieve the required diameter inconsistency, sphericity, surface roughness, and mutual difference, and becomes a ceramic sphere as a product. Become.

According to the method for manufacturing a ceramic sintered body according to the above embodiment, the formed body IC formed by uniaxially pressing the ceramic raw material powder 7 is further isostatically compressed by wet cold isostatic pressing treatment and pressure molded. Therefore, the formed body 1c is pressurized evenly over the entire surface, and the density is made uniform.

As a result, there is little reduction in dimensional accuracy, less occurrence of cracks during manufacturing, and it is possible to improve product yield.

Moreover, since the formed body IC is obtained by compression molding the raw material powder 7 using the upper and lower punches 4.5 having hemispherical pressing surfaces 3a and 3b, it is formed into a shape close to a spherical shape. Therefore, compared to the conventional method of cutting and molding from a cylindrical shaped body, it is possible to significantly improve the yield of the product based on the raw material powder, and it also has the effect of facilitating the polishing work after sintering. This makes it possible to significantly reduce the manufacturing cost of ceramic spheres.

In addition, in the cold isostatic pressing process, a storage bag 9 made of two layers of flexible nylon and polyethylene is used, and the inlet opening is sealed by heat sealing, so that the formed body 1c The sealing process of the opening after accommodating the container is extremely easy, and the work cost can be significantly reduced.

In other words, in the cold isostatic pressing process that has been generally adopted, the formed body 1c is placed in a thick rubber storage bag.
It was necessary to evacuate the inside of the bag in advance to prevent air from remaining inside the bag. However, if a flexible thin nylon-polyethylene double-layer bag 10 is used as the storage bag as in this embodiment, the air inside can be quickly expelled simply by pressing the entire storage bag with your hand. This makes it possible to simplify the preparation work for cold isostatic pressing.

Next, the effects of specifically manufacturing a ceramic sphere using the method for manufacturing a ceramic sintered body of the above embodiment will be explained in comparison with a conventional method.

Example 1 and Comparative Example 1 As Example 1, 513N4 powder was mixed with 5% by weight and 5% by weight of alumina (Y2O2) and alumina (AJ203) as sintering aids, respectively, and wet-mixed in a ball mill for 48 hours. A binder was added to the resulting slurry-like mixture, which was then dried with a spray dryer to granulate a powder of the mixture having an average particle size of 60 μm. Next, using the granulated powder, press the die press machine shown in Fig. 1 at 50°C.
The upper and lower punches were pressed at 0 kg/al to form 500 formed bodies with a diameter of 9.5 mm.

Next, the obtained formed bodies 1c are filled one by one into a storage bag 9 formed into a two-layer structure of nylon and polyethylene as shown in FIGS. 3(a) to 3(C), and the inlet opening of the storage bag is After heat-sealing, wet cold isostatic pressing was performed at a pressure of 2000 kg/cor for 5 minutes.

Next, the obtained formed body 1c was placed in a N2 gas atmosphere for 7
After degreasing at 00°C, normal pressure sintering was performed at 1800°C, and further hot isostatic pressing (HIP) treatment was performed at a temperature of 1800°C and a pressure of 1000 kg/ad for 1 hour.

Furthermore, the sintered body obtained by HIP treatment was treated with a barrel polishing device shown in Fig. 4, and then lap polishing was performed using diamond paste as a compound.
μm1 Vacuum degree 0.4μm1 Surface roughness 0.032μmRa
The total manufacturing time until dimensional accuracy with a mutual difference of 0.8 μm was obtained and the number of sintered bodies that cracked during manufacturing were measured.

On the other hand, as Comparative Example 1, the same number of ceramic spheres were manufactured according to the conventional manufacturing method without wet cold isostatic pressing using a formed body having the same dimensions as in Example 1, and the manufacturing time and cracking occurred. The number of sintered bodies was measured in the same manner, and the results shown in Table 1 were obtained.

As is clear from the results in Table 1, according to the method for manufacturing ceramic spheres of this example, there is little decrease in dimensional accuracy at the stage of the formed body, so finishing by polishing is easy and manufacturing time is shortened. Ru.

In addition, wet cold isostatic pressing is used to make the resulting product denser and more uniform in density, resulting in fewer cracks and a significant improvement in product dripping.

As Example 2, after uniaxial pressure molding was performed using the same raw material composition and processing conditions as in Example 1, the formed body was filled into a nylon-polyethylene double layer bag, subjected to wet cold isostatic pressing treatment, and further degreased and sintered. 100 ceramic spheres were manufactured.

On the other hand, as a comparative example, the formed body formed by the uniaxial pressure press molding machine of Example 1 was molded into a conventional thick rubber mold (accommodation bag).
After loading, the inside was evacuated and the opening of the rubber mold was sealed with metal fittings, and then wet cold isostatic pressing was performed under the same pressurizing conditions as in Example 2, and under the same conditions as in Example 2. 100 sintered bodies were manufactured by degreasing and sintering. Further, as Comparative Example 3, the green body formed using the uniaxial pressure press molding machine of Example 1 was directly degreased and sintered to produce 100 sintered bodies.

Then, for each sintered body obtained in Example 2 and Comparative Examples 2 and 3, the sintered density, the occurrence of bores, the occurrence of cracks, and the yield of the sintered body that finally passed as a product were measured and calculated. The results shown in Table 2 below were obtained.

As is clear from the results in Table 2, according to the method for manufacturing a ceramic sintered body according to Example 2, the sintered body density is high;
A high-quality ceramic sintered body with no defects can be manufactured at a high yield.

On the other hand, according to Comparative Example 2, the formed body was housed in a rubber mold and the CIP treatment was performed, so although the density of the sintered body was the same as in Example 2, it was not possible to completely seal the opening of the rubber mold. This was difficult, and there was a high rate of pressurized water entering the rubber mold and contaminating the formed body during the CIP treatment, and the yield of the product decreased to about 80%.

In addition, in Comparative Example 3, since CIP treatment was not performed, the densification and uniformity of the density of the formed body did not progress, and most of the sintered bodies had bores, many cracks occurred, and the yield was 10%. It will decrease to a certain extent.

Next, another embodiment of the present invention will be described with reference to FIGS. 5 to 7. The uniaxial pressure press molding machine shown in FIG. 5 is a molding machine used to form a rivet-like sintered body 300 as shown in FIG. An upper bunch 4a having a hemispherical pressing surface 3C formed together and a lower bunch 5a having a stepped pressing surface 19 formed to match the shape of the lower surface of the sintered body 300 are inserted into the die 6 from above and below, respectively. It is configured to fit in. A core punch 20 is disposed in the shaft hole of the lower bunch 5a so as to be movable up and down.

Then, when the ceramic raw material powder 7 is filled into the gap between the upper and lower bunches 4a, 5a and the core bunch 20 and pressed,
A rivet-shaped generated body 1d as shown in FIG. 6 is obtained.

Next, the obtained green body 1d is placed in a storage bag 9 formed of a nylon-polyethylene double layer bag 10, as shown in FIG. 7, and sealed. Each of the formed bodies 1d is sealed one by one in each area 21 defined by the heat-sealing lines 11 formed in the vertical and horizontal directions in the storage bag 9.

The sealed green body 1d is loaded into a CIP device. Then, a predetermined hydrostatic pressure is applied uniformly to the surface of each formed body 1d through the storage bag 9, and the formed body 1d is densified.

According to the method of this embodiment, even a sintered body having a complicated rivet shape can be manufactured efficiently, and in particular, a plurality of formed bodies 1 can be housed in one storage bag 9.
Since the CI
Adjacent formed bodies rarely come into contact with each other during P processing.

Therefore, there is less damage to the formed body, and the yield of the product can be increased.

〔Effect of the invention〕

As explained above, according to the method for manufacturing a ceramic sintered body according to the present invention, the formed body formed by uniaxially pressing the ceramic raw material powder is further pressure-molded by a wet cold isostatic pressing method. The entire surface of the generated form is pressurized evenly towards the center by isostatic hydrostatic pressure. As a result, densification progresses further and the density of the formed body becomes uniform throughout. Therefore, there is less loss of dimensional accuracy,
Furthermore, cracks are less likely to occur during the molding and sintering stages, and the product yield can be greatly improved.

In addition, the formed body is obtained by compression molding the raw ceramic powder using upper and lower punches whose pressing surfaces match the upper and lower shapes of the sintered body to be formed. A near-net generated shape that is close to the shape of the solid body can be obtained.

Therefore, compared to the conventional method of cutting and molding from a cylindrical shaped body, it is possible to significantly improve the yield of the product based on the raw material powder, and it also has the effect of facilitating the polishing work after sintering. This makes it possible to significantly reduce the manufacturing cost of ceramic sintered bodies.

In addition, the formed body is stored in a flexible synthetic resin storage bag, and the entrance opening of the storage bag is sealed by heat sealing, and then the sealed storage bag is immersed in water to apply hydrostatic pressure. By adopting a wet cold isostatic press process that compresses the product isostatically, a thick rubber bag can be used as a storage bag.
Compared to the conventional cold isostatic pressing process in which the inlet part of the rubber bag is firmly fastened with a fastener, the sealing process is extremely easy and the work cost can be significantly reduced.

[Brief explanation of drawings]

Fig. 1 is an embodiment of the present invention, and is a sectional view showing a state in which a ceramic raw material powder is uniaxially pressed to form a formed body, Fig. 2 is a front view showing an example of the shape of the formed body, and Fig. 3 ( a
) to (C) are front views showing the implementation procedure of the wet cold isostatic press treatment, FIG. 3(c) is a front view showing the state in which the opening of the storage bag is sealed by heat sealing, FIG. 3(c) is a front view showing the state in which hydrostatic pressure is applied to the storage bag containing the generated body, and FIG. 4 is the barrel. 5 is a cross-sectional view showing another example of the structure of the uniaxial pressure press molding machine used in the method of the present invention, and FIG. 6 is a cross-sectional view showing the configuration of the polishing device. FIG. 7 is a front view showing an example of the shape of the formed formed body; FIG. 7 is a perspective view showing a state in which a plurality of formed bodies are separated from each other and sealed in a storage bag; FIG. 8(a)
9(d) are front views showing examples of shapes of ceramic sintered bodies, FIGS. 9(a) to 9(d) are views showing conventional manufacturing procedures of ceramic spheres, and FIG. 9(a) is a circular view. Perspective views of generated bodies formed into columnar shapes, FIGS. 9(b) and (c)
FIG. 9(d) is a perspective view showing a state in which the corners of the cylindrical generated shape are chamfered in a straight line or a curve, respectively.
1 is a perspective view showing a ceramic sphere that has undergone final surface processing, and FIG. 10 is an enlarged sectional view of the X section in FIG. 2. 1, la, Ib, lc... generated form, 2
... Ceramic sphere, 3a, 3b, 3c... Hemispherical pressing surface, 4.4a... Upper haunch, 5.5a... Lower bunch, 6... Dice, 7... Ceramic raw material powder , 8... Cylindrical part, 9... Storage bag, 10... Nylon-polyethylene double layer bag, 11... Heat seal wire, 12... Barrel polishing device, 13... Substrate, 14...
...Metal bond polishing whetstone, 15...Sintered body, 16.
...Device body, 17...Cover 18...Cracked, 19
... Stepped pressing surface, 20 ... Core punch, 2 ... Region, R ... Hemispherical part. $1 Figure $2 times (a) KoIノ(() Figure 4 Base times 2/ 2/ times θ times

Claims (1)

[Claims] 1. The ceramic raw material powder is uniaxially pressed by an upper punch and a lower punch whose pressing surfaces are respectively formed to match the upper and lower shapes of the sintered body to be formed to form a formed body. A ceramic sintered body characterized in that, after being formed, the above-mentioned green body is pressure-formed by wet cold isostatic pressing, and then the green body obtained is degreased and sintered, and then subjected to a final surface treatment. manufacturing method. 2. In the wet cold isostatic pressing process, the formed body is placed in a flexible synthetic resin storage bag, and the inlet opening of the storage bag is heated while the pressure inside the bag is maintained below atmospheric pressure. 2. The method for producing a ceramic sintered body according to claim 1, wherein after sealing, the sealed storage bag is immersed in water and isostatically compressed by applying hydrostatic pressure.