JPH064504B2 - Method for manufacturing ceramics sintered body - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for producing a ceramics sintered body, and more specifically, a ceramics sintered body using a kneaded clay mainly containing water as a plasticizing medium. The present invention relates to a manufacturing method of.

[Conventional technology]

Conventionally, a casting molding method and an injection molding method are known as molding methods for structural ceramic parts having a complicated shape such as a turbine wheel.

The cast molding method is a method in which a slurry of ceramic powder is poured into a casting mold such as gypsum and solidified to obtain a molded body. Cast molding using a gypsum mold or the like can form a complicated shape, but the precision of the mold is poor, and the dimensional accuracy of the molded product may be poor. In addition, since a large amount of water is generally used as a medium, a long time is required for molding.

The pressure casting method is a method of pouring a slurry of ceramic powder into a permeable casting mold, discharging a large amount of water from the permeable casting mold by pressurizing, and solidifying to obtain a molded body. is there. Although this method is capable of molding a complicated shape, it requires a long time for molding because the shape retention is poor and the mold release is difficult.

The injection molding method is a method in which several kinds of thermoplastic organic binders are added to ceramic powder, mixed and heated, injected into a mold and cooled and solidified to obtain a molded body. This injection molding method can mold complex shapes and is suitable for mass production, but in the organic binder removal so-called degreasing process, cracks in the molded body,
In order to prevent deformation, it usually requires heating for a long time of 100 hours or more, and moreover, it can be applied only to thin parts.

Further, in Japanese Patent Laid-Open No. 61-10405, it is proposed to perform injection molding using fine ceramics such as Al ₂ O ₃ , SiC, Si ₃ N ₄ and ZrO ₂ with a slurry containing water and an organic additive. . However, this method uses a special porous mold, holds the pressure after injection at 100 to 600 kg / cm ² and dehydrates from the slurry to obtain green, and the work for taking out the molded product from the mold is Not easy.

In addition, the conventional compression molding method or transfer molding method in ceramics molding is relatively easy to operate, but is only applied to small and thin ceramics and the like, and is used for structures with complicated shapes such as the turbine wheel. It has not been applied to ceramic parts.

[Problems to be Solved by the Invention]

The present invention eliminates the above-mentioned drawbacks of the prior art, and injection molding,
In the method for manufacturing a ceramics sintered body, which obtains a molded body by transfer molding or the like, removes water and an organic binder, and then fires it to obtain a sintered body, the manufacturing process and the number of manufacturing days can be significantly reduced. It is an object of the present invention to integrally obtain a sintered body having a complicated shape such as a turbine wheel shown in FIG. 2 by injection molding, compression molding or transfer molding. For the above purpose, the inventors have mainly used water as a plasticizing medium, which has not been used in conventional injection molding, and kneaded clay using an organic binder as a plasticizer for injection molding, compression molding or transfer molding. The present invention has been accomplished as a result of earnestly studying forming a thick part having a complicated shape by applying it and obtaining a sintered body.

[Means for Solving the Problems]

According to the present invention, a molded body obtained by injection molding, compression molding or transfer molding using a kneaded material containing a ceramic powder, a sintering aid, water and an organic binder and prepared by a vacuum clay kneader is used. And remove the organic binder,
There is provided a method for manufacturing a ceramics sintered body, which is characterized by the subsequent firing. In the case of compression molding or transfer molding, a heat gel-curable organic binder is used.

[Work]

The case where injection molding is used will be mainly described in order to explain the present invention in detail. The same applies to other compression molding and transfer molding.

That is, in the present invention, first, water is mainly used as a plasticizing medium for the ceramic powder such as an inorganic solid material containing a sintering aid, and an organic binder is used as a plasticizer to obtain moldability,
A kneaded clay with good shape retention is obtained. Then, injection molding using the obtained kneaded material, a molded body is manufactured with good dimensional accuracy and good release yield, after which water and organic binder are removed in a short time,
It is possible to obtain a sintered body by firing. The sintered body aimed at by the present invention obtained here is a structural ceramic component such as a ceramic gas turbine wheel, which usually has a complicated shape and has a wall thickness, and which requires high strength and high reliability, If the sintered body has defects such as minute gaps or voids, the product value is lost. Therefore, the kneaded clay used in the present invention has 1) air bubbles or the like that cause defects are removed by a vacuum kneading machine, and 2) it has excellent shape-retaining property, so that the molded product retains its shape-retaining property without dehydration during molding. Can be given,
3) Since it has excellent fluidity, it has characteristics such that defects such as weld do not occur during molding. It should be noted that clay and the like used in old ceramics and the like are not included in the kneaded clay of the present invention.

In the kneaded clay used in the present invention, water is mainly used as a plasticizing medium and an organic binder is used as a plasticizer in appropriate amounts as described above. The effect of using an appropriate amount of water is (1) in the water removal process, water does not cause thermal decomposition and has a low coefficient of thermal expansion.
Water can be easily removed in a short time without causing defects in the molded product. (2) Since the molded product becomes euphoric due to the scattering of water, the binder removal in the post process can be easily done in a short time due to a rapid temperature rise. (3) The binder can be easily removed from the thick molded body, for example, the turbine wheel shown in FIG. 2 for the same reason as (2).

The effect of using an appropriate amount of organic binder is that, for example, when an organic binder that cures with heat gel is used, the molded product is given more strength by curing with heat gel during molding, and shape retention can be increased. These effects are large effects obtained by using the kneaded clay of the present invention. Water removal, that is, drying is usually carried out in a constant temperature and constant humidity tank or the like, and binder removal is usually carried out in an oxidizing atmosphere furnace (calcining furnace) or the like.

The injection molding method using the kneaded clay in the present invention can remove the binder (degreasing) in an extremely short time compared to the injection molding method in which a large amount of the conventional organic plasticizer is used, and cast molding using a large amount of water. Can be molded in an extremely short time as compared with the molding method and the pressure casting molding method. Further, by applying the above-mentioned kneaded material to a compression molding method or a transfer molding method, it is possible to mold a structural ceramic having a complicated shape wall thickness which has not been conventionally molded by these methods.

A rheometer is usually used as the method and apparatus for evaluating the fluidity of kneaded clay, but a flow tester or melt indexer used in conventional injection molding can also be used.

The ceramic powder used in the present invention may be any of ceramic materials such as carbides such as silicon carbide, silicon nitride, sialon and boron nitride, non-oxide type such as nitrides and oxide type such as zirconia. The ceramic raw materials may be used alone or in combination of two or more depending on the intended use of the obtained molded part. It is preferable to use silicon nitride as a main component when the molded part to be produced is particularly required to have high heat resistance and mechanical strength such as structural ceramic parts.

The ceramic powder used in the present invention is (1) excellent in miscibility with water and an organic binder, formability by vacuum clay kneading, and becomes a good kneaded clay with good shape retention, (2) between powder particles Has a low slip resistance, excellent fluidity, does not cause defects such as flow patterns in the molded body, (3) does not cause defects during drying and binder removal, and does not reduce the strength of the sintered body, etc. It is better to have the requirements of. The ceramic powder satisfying these requirements is preferably particles within the range represented by the following formula.

In the present invention, the average particle size according to the above-mentioned grain soil distribution is based on the particle size distribution according to the laser diffraction method measured by, for example, Leeds & Nostrap Co. Microtrake 7995-30 type particle size distribution measuring device. is there. Further, the specific surface area particle diameter by the adsorption method of the above formula is obtained from the specific surface area by the BET adsorption method measured by, for example, Shimazu Seisakusho Flow Soap Model 2300 Specific Surface Area Measuring Device, based on the following equation. In this case, the density is determined by the ceramic powder used, and for example, silicon nitride (Si ₃ N ₄ ) is 3.18.

Specific surface area according to adsorption method Particle size = 6 / density / specific surface area ... The kneaded material using the ceramic powder of 5 or less represented by the above formula has excellent formability, does not cause defects in the obtained molded body, and is sintered. The body is not defective. When the above range is more than 5, a flow pattern at the time of molding remains, or pores and cracks occur in a molded body in which the flowability of the kneaded material is poor.

The sintering aid used in the present invention is alumina, magnesia, beryllia, cerium oxide, strontium oxide, titania,
Oxides such as zirconia and yttria, beryllium titanate, complex oxides such as lead zirconate titanate, mullite,
It is an oxide such as a multi-component oxide such as aluminum zirconate titanate. The sintering aid preferably has a particle shape similar to that of the ceramic powder.

The water added as a plasticizing medium to the ceramic powder is
Ceramic powder 100 in kneaded clay to be used for molding of the present invention
It is 10 to 50 parts by weight with respect to parts by weight. If the water content is less than 10 parts by weight, the kneading property is poor and a homogeneous kneaded material cannot be obtained.
If it exceeds the weight part, it becomes a slurry state and a dehydration treatment is required during the molding, which is not preferable.

The organic binder used in the present invention is a water-soluble or water-absorbing organic compound, for example, a water-soluble cellulose ether derivative such as methylcellulose or hydroxypropylmethylcellulose, a water-soluble polymer such as polyvinyl alcohol or polyethylene glycol, and a water-absorbing polymer of those derivatives. Etc. are used. Preferably at least thermal gel curing (thermogel curing is a phenomenon described in the sample “Extrusion molding of new ceramics using methylcellulose” in “New Ceramics Adhesive Technology Lecture” held in February 1984) Of these, for example, methyl cellulose, hydroxypropyl methyl cellulose, alkylene oxide cellulose derivative and the like are used. The organic binder acts to improve the water retention of the kneaded clay used in the present invention and to maintain the plasticity, and if a heat gel curable material is used, the heat gel is cured during the molding of the present invention to enhance the shape retention. In addition, the releasability is improved.

The content of organic binder in the kneaded clay is 10 ceramic powder.
0.1 to 15 parts by weight is preferable to 0 parts by weight. If it is less than 0.1 part by weight, the strength of the molded product is low and the shape retention is poor, and if it exceeds 15 parts by weight, the binder removal time becomes long and cracks are easily generated in the molded product, which is not preferable.

The kneaded clay in the present invention may contain a surfactant or the like other than the above-mentioned ones.

The above-mentioned ceramic powder, sintering aid, water and organic binder are mixed, then kneaded and vacuum kneaded to prepare a kneaded clay. The components may be prepared by mixing all the components into a kneaded clay, but preferably the ceramic powder and the sintering aid are first prepared. In this case, the crushed ceramic powder having the above-mentioned particle shape and the sintering aid may be mixed, but the mixture of the ceramic powder and the sintering aid is crushed and mixed together to obtain the particle shape used in the present invention. It is good to say The pulverization and mixing can be carried out, for example, with an attritor by adding water using a boulder such as silicon nitride.

The ground mixture of ceramic powder and sintering aid is then dried. If necessary, you may remove iron before drying. Iron removal can be performed using, for example, a wet ferro filter. The drying is preferably spray drying with a spray dryer. The treatment in the spray dryer has an advantage that granulation can be performed at the same time as drying, and the organic binder can be easily removed later. After drying, if necessary, the particles can be sized using a vibrating screen.

Water and an organic binder are added to the dried pulverized mixture, and the mixture is kneaded. The kneaded product is vacuum degassed usually at 70 mmHg or more using a vacuum clay kneader to obtain, for example, a cylindrical kneaded clay. Examples of the clay kneader (extruder) for preparing kneaded clay include a pug mill, a vacuum pug mill, an auger machine, and a piston type extruder, and these may be combined. A homogenous kneaded clay is usually prepared by a vacuum clay kneader, but if it is difficult to obtain a homogeneous kneaded clay, isostatically press the kneaded clay with a rubber press machine to further defoam and homogenize it. May be. The kneaded material obtained as described above is subjected to the molding of the present invention, but may be subjected to the molding of the present invention after being aged in a dark place.

The injection molding used in the present invention (for example, vertical type, horizontal type and in-line screw type are used).
Molds such as molds closed through injection molding nozzles: injection spray, injection runner and injection gate, or injection spray and injection gate (direct gate)
It is carried out by injecting a kneaded material into the molding die injection introducing part and the molding body die. Any injection molding nozzle may be used, and a known one may be used. The shape of the injection introduction portion is not particularly limited, but it is preferable to use an injection sprue portion of a direct gate or an injection runner formed in a tapered shape having an angle from the injection gate. Generally, the dater angle is set to 2 to 10 degrees.

For injection molding, molding conditions may be selected according to the type of kneading used, the injection machine, the molding die, and the like. In the present invention, the pressure is usually 50 to 1000 kg / cm ² , and the pressure time is 1 to 200.
The injection speed may be 50 seconds to 1000 cc / sec. The kneading temperature is usually 5 to 20 ° C.

The compression molding or transfer molding may be performed by forming a molded body mold according to the purpose in a known molding machine. In these methods, generally, a kneaded clay having an appropriate shape is placed in a mold or a cylinder, and compressed by an upper mold or a piston,
The plasticity of the kneaded clay is used to deform along the mold body to form a molded body.

The kneaded material poured into the molded body mold is formed into a molded body by the molded body mold. In this case, when the kneaded clay added with the organic binder capable of heat gel curing is used, the heat gel is cured by the action of the added organic binder. The mold can be released in a short time by heating near the heat gel curing temperature of the organic binder that heat-molds the mold in advance. Further, since the strength is imparted to the molded article, the dimensional accuracy of the molded article is good, the handling becomes easy, and the molded article can be manufactured with a high molding yield. In this case, the conditions of the molding die, such as the mold, are appropriately selected depending on the type and amount of the added organic binder, the injection temperature and water content of the kneaded clay, the shape and size of the molded product. Generally, the mold temperature may be set within the range of (T-10) ° C to (T + 25) ° C with respect to the heat gel curing temperature T of the organic binder capable of heat gel curing. For example, when methyl cellulose is used as the organic binder, it can be heat-gel cured by preheating and treating the mold, usually about 45 to 75 ° C.
Done in. The organic binder that is hardened by heat gel is preferably applied to a complex shaped product such as a turbine wheel,
It is not necessary for simple shaped products.

The mold used for the molding of the present invention preferably has a water repellent treatment on its inner surface. The water-repellent treatment preferably has a contact angle with water of about 80 ° or more. The water-repellent treatment may be a silicone treatment or a Teflon-treated treatment. When these water-repellent molds are used, the dimensional accuracy of the molded product is good, the surface roughness of the molded product is small, and the release yield is high.

After injection molding, compression molding or transfer molding, drying,
After calcination to remove water and organic binder, the product is fired to obtain a molded product.

Drying is performed by humidity control drying, dielectric drying, electric current drying, dielectric heating drying and the like, and usually humidity drying is performed using a constant temperature and constant humidity dryer. It is generally carried out at 40 to 100 ° C., though it depends on the drying temperature and the size of the molded product. Drying is performed while sequentially lowering the humidity, and finally lowering the humidity to about 10%. The dried injection-molded article may be subjected to isostatic pressing under hydrostatic pressure if necessary. After drying, the shaped body has the organic binder removed.
Binder removal depends on the type of molded product, but is usually 10
℃ / Hr ~ 100 ℃ / Hr heating up at about 500 ℃ 1-1
It is carried out by heating the molded body for 0 hour to burn off the organic binder. AlO ₂
It may be embedded in O ₃ powder or the like. After removing the binder, a hydrostatic isostatic pressing process may be performed if necessary.

After removing the binder, the molded body is fired to obtain a sintered body. The firing conditions are appropriately determined depending on the type of ceramics, purpose of use, and the like. For example, when manufacturing a silicon nitride sintered body, it is 1600 to 1800 ° C. in normal pressure firing and 1700 in pressure firing.
It is preferable to perform firing in a nitrogen gas atmosphere at ˜2000 ° C. In the case of producing a silicon carbide sintered body, it is preferable to carry out firing under normal pressure in an argon atmosphere at 1900 to 2200 ° C. Further, when producing a partially stabilized zirconia sintered body, it is preferable to perform firing in an air atmosphere at 1300 to 1500 ° C. under normal pressure.

〔Example〕

The present invention will be described in more detail by the following examples.
However, the present invention is not limited to this embodiment.

(Preparation of Grinding Mixture) 100 parts by weight of silicon nitride, 2 parts by weight of strontium oxide, 3 parts by weight of magnesia, and 3 parts by weight of cerium oxide were wet-ground and mixed with an attritor. The crushed mixture after crushing had an average particle size of 0.6 μm and a specific surface area of 6.3 m ² / g. The value of the above formula in this case is 2.0 as the density of silicon nitride 3.18.
Met. After pulverization, the pulverized mixture was deironed with a wet type ferro filter mini shifter, and then dehydrated and dried with a spray dryer.

(Preparation of kneaded clay) 100 parts by weight of the dry ground mixture obtained as described above, 7 parts by weight of methyl cellulose (trade name: SM-4000), and a surfactant (trade name: Cedran FF-200).
1 part by weight and 30 parts by weight of water were kneaded while cooling with an open kneader. Then, using a vacuum clay kneader, 70
Extrusion was performed 3 times at mmHg or more to obtain a cylindrical kneaded clay having a diameter of 52 mm and a length of 500 mm. Furthermore, with a rubber press machine, pressure
It was pressed at 2.5 t / cm ² to obtain a homogeneous kneaded material A.

Similarly, the average particle size of the crushed mixture of ceramic powders was 0.86, 0.75, and 0.95μ, respectively, by the method shown above.
m and specific surface area of 9.4, 13.3, 16.8 m ² / g,
The kneaded materials B, C, and D were obtained from the crushed mixtures whose respective values were 4.3, 5.3, and 8.5.

Example 1 (Injection molding) The kneaded material A was aged in a refrigerator at 12 ° C overnight and then used for injection molding.

(1) Turbine wheel sintered body Diameter 13 shown in FIG. 2 along with the process chart shown in FIG.
A 0 mm turbine wheel sintered body was manufactured. The molded body was integrally injection-molded by the method schematically shown in FIG. The mold used had a thickness of 20 μm on the inside of both the upper and lower molds.
Teflon processed, and had a contact angle with water of 105 degrees. The kneaded material temperature was 12 ° C., the mold temperature was 60 ° C., the pressure was 300 kg / cm ² , the pressing time was 10 seconds, and the injection speed was 300 cc / sec.

After the injection molding, the molded body was taken out of the mold and dried. Dry 6
In a thermo-hygrostat heated to 0 ° C., the temperature was kept at 60 ° C. for 2 hours, then the temperature was raised at 10 ° C./hr, and the temperature was kept at 100 ° C. for 3 hours. The humidity inside the thermo-hygrostat was initially 98%, but the humidity was reduced to about 10% / hr and the humidity was dried to 20%.

After drying, the organic binder was removed. To remove the binder, the temperature is raised in the air at 50 ° C./hr and heated at 500 ° C. for 5 hours to remove the organic binder. The number of days required for drying and removing the binder was 2 days. After removing the binder, the molded body was rubber-pressed at a pressure of 7 t. The obtained molded body was fired. Firing is performed at a temperature of 700 ° C / hr in a nitrogen atmosphere at 1650 ° C.
For about 1 hour to obtain a turbine wheel sintered body A having no defects on the surface or inside. The number of days required for all the above steps was 7 days.

Similarly, a die temperature was changed from 25 ° C. to 83 ° C. to manufacture a fired body. The results are shown in Table-1 and FIG. When the deformation of the blade portion in Table-1 is x, the deformed portion of the blade shown in Fig. 4, that is, the blade tip portion is deformed by its own weight at the stage of releasing from the molding die after molding, and remains deformed after firing. It means that the product value has been lost. In addition, if the number of cracks is x, it is 4th at the stage of releasing.
This means that a crack, that is, a crack has occurred on the surface of the molded body such as the crack portion shown in the figure. Although these cracks disappeared by the rubber press after removing the organic binder, surface cracks were slightly detected by the zycro method inspection after firing, and it became unsuitable as a product. On the other hand, in Table-1, the ones with ○ are neither the deformation of the blades nor the generation of cracks, the contour shape of the blades after firing matches the design specifications of the mold, and the surface by the zycro method inspection. No defects were found, which means that an excellent product was obtained with high accuracy. As is clear from this result, it is preferable to set the mold around the hot gel curing temperature of methyl cellulose of about 52 ° C., that is, in the range of 42 to 77 ° C. to perform the heat gel curing.

(2) Complicated shape test piece molded article The complex shape test piece molded body having a diameter of 90 mm shown in Fig. 7 was prepared in the same manner as in (1) above, and the kneaded materials A, B and C were prepared.
And D were injection-molded to obtain molded test piece compacts A, B, C and D, respectively.

The cross-sectional properties of each molded product were inspected. The result is No. 8
As shown in the figure. As is clear from FIG. 8, it is understood that the ceramic powder having a particle shape within the range of the formula does not need cracks and pores.

[Comparative example]

A turbine wheel similar to that used in Example (1) in injection molding was molded by conventional injection molding according to the process chart shown in FIG. 5 to obtain a sintered body. In this case, integral molding cannot be performed. As shown in FIG. 5, the hub portion and the blade portion are separately molded, and then joined and integrated by a rubber press. Further, as the pulverized mixture, the same pulverized mixture as in the example was used, but the degreasing of the blade portion had to be performed at a temperature rising rate of 0.5 to 3 ° C./hr.
It took 60 days to complete all the steps shown in FIG.

Further, a turbine wheel was similarly molded by the conventional pressure cast molding according to the process chart shown in FIG. In this case as well, the same crushed mixture as that used in the example was used, and a slurry of 44% water and 1% peptizer was degassed and then press-cast. It was pressed at a pressure of 2 kg / cm ² for 24 hours, but it could not be molded due to insufficient inking.

Example 2 (Compression molding) The kneaded clay A was aged in a refrigerator at 12 ° C overnight and then used for compression molding.

The diameter 90 shown in FIG. 7 along with the process chart shown in FIG.
mm A complex shape test piece sintered body was manufactured. The molded body is
Compression molding was carried out by the method schematically shown in FIG. The mold used was a Teflon film having a thickness of 20 μm on the inside of each of the upper mold and the lower mold, and had a contact angle with water of 105 degrees. The kneaded clay temperature was 12 ° C., the mold temperature was 60 ° C., and the mixture was molded under a pressure of 300 kg / cm ² and left for 3 minutes for curing the heat gel.

After compression molding, the molded body was taken out from the mold and dried. Dry 6
In a thermo-hygrostat heated to 0 ° C., the temperature was kept at 60 ° C. for 2 hours, then the temperature was raised at 10 ° C./hr, and the temperature was kept at 100 ° C. for 3 hours. The humidity inside the thermo-hygrostat was initially 98%, but the humidity was reduced to about 10% / hr and the humidity was dried to 20%.

After drying, the organic binder was removed. The binder was removed by heating in air at 50 ° C./hr and heating at 500 ° C. for 5 hours to remove the organic binder. The number of days required for drying and removing the binder was 2 days. After removing the binder, the molded body is
Rubber pressed at a pressure of t. The obtained molded body was fired. The firing was carried out at a temperature of 700 ° C./hr in a nitrogen atmosphere and at 1650 ° C. for about 1 hour to obtain a test piece sintered body having a complicated shape with no defects on the surface or inside. The number of days required for all the above steps was 7 days.

Example 3 (Transfer molding) The kneaded material A was aged overnight in a refrigerator at 12 ° C and then used for transfer molding.

The diameter 1 shown in FIG. 2 along the process diagram shown in FIG.
A 30 mm turbine wheel sintered body was produced. The molded body was integrally transfer-molded by the method schematically shown in FIG. The mold used was a Teflon film having a thickness of 20 μm on the inside of each of the upper mold and the lower mold, and had a contact angle with water of 105 degrees. The kneaded clay temperature was 12 ° C., the mold temperature was 60 ° C., the pressure was 300 kg / cm ² , the pressurizing time was 10 seconds, and the piston descending speed was 300 cc / sec.

After transfer molding, the molded body was taken out of the mold and dried.
Drying was carried out by holding in a thermo-hygrostat heated to 60 ° C. at 60 ° C. for 2 hours, then raising the temperature at 10 ° C./hr and holding at 100 ° C. for 3 hours. The humidity inside the thermo-hygrostat was initially 98%, but the humidity was reduced to about 10% / hr and the humidity was dried to 20%.

After drying, the organic binder was removed. The binder was removed by heating in air at 50 ° C./hr and heating at 500 ° C. for 5 hours to remove the organic binder. The number of days required for drying and removing the binder was 2 days. After removing the binder, the molded body was rubber-pressed at a pressure of 7 t. The obtained molded body was fired. The firing was performed at a temperature of 700 ° C./ht in a nitrogen atmosphere and was performed at 1650 ° C. for about 1 hour to obtain a turbine wheel sintered body having no defects on the surface or inside. The number of days required for all the above steps was 7 days.

〔The invention's effect〕

INDUSTRIAL APPLICABILITY The present invention mainly uses water as a plasticizing medium and uses a small amount of an organic binder to integrally form a molded article having a thick portion, which is difficult to integrally mold in conventional injection molding. Since it can be injection-molded and the organic binder can be removed in a short time, it is possible to easily obtain a ceramics sintered body having a complicated shape. Further, using a water-soluble or water-absorbing polymer as the organic binder, preferably by using a water-soluble or water-absorbing polymer capable of thermal gel curing, such as methyl cellulose, because it can be gel-cured in the mold, A molded product having good moldability and shape retention can be obtained by injection molding. Further, by drying the formed body, removing the organic binder, and firing it, a ceramics sintered body can be obtained with good precision and yield.

Further, in the present invention, as described above, mainly water is used as the plasticizing medium, and by using a small amount of the organic binder, it is possible to obtain a large and complicated shape which has not been formed by the conventional compression molding and transfer molding. A structural component having a wall thickness can be molded, dried, binder-removed, and fired to obtain a ceramic sintered body with good precision and yield.

As described above, according to the method of the present invention, it is possible to form a thick ceramics molded body by integral injection molding, which has been difficult in conventional injection molding, and further, to form a structural ceramic component having a complicated shape by injection molding, compression molding or transfer molding. It can be obtained, and the subsequent manufacturing period such as drying, binder removal and firing is greatly shortened, which is extremely useful industrially.

[Brief description of drawings]

FIG. 1 is a process block diagram by injection molding of the method for producing a ceramics sintered body of the present invention. FIG. 2 is a sectional view of a turbine wheel molded body, and FIG. 3 is a schematic sectional view of an injection molding system. FIG. 4 is a diagram showing defects in the sintered body of the turbine wheel compact. FIG. 5 is a process diagram of conventional injection molding and a cross-sectional view of a hub portion and a blade portion of a turbine wheel. FIG. 6 is a process drawing of pressure casting. FIG. 7 is a sectional view of a test piece compact having a complicated shape. FIG. 8 is a cross-sectional property diagram of a test piece compact having a complicated shape. FIG. 9 is a process block diagram by compression molding of the method for producing a ceramics sintered body of the present invention, and FIG. 10 is a schematic sectional view of compression molding. FIG. 11 is a process block diagram by transfer molding of the method for producing a ceramics sintered body of the present invention, and FIG. 12 is a schematic cross-sectional view of transfer molding. 1 ... Kneaded clay, 2 ... Piston, 3 ... Cylinder, 4 ... Nozzle, 5 ... Movable plate, 6 ... Mold upper mold, 7 ... Mold lower mold, 8 ... Molded body, 9 ... Exhaust hole, 10 ... Crack, 11 ... Pore, 12 ... Movable plate, 13 ... Mold upper mold, 14 ... Mold lower mold, 15 ... Fixed plate, 16 ... Piston, 17 ... Cylinder, 18 ... Movable plate, 19 ... Upper mold, 20 ... Lower mold , 21 ... Molded body.

Claims (7)

[Claims] 1. Water and an organic binder are removed from a molded body obtained by injection molding using a kneaded clay containing a ceramic powder, a sintering aid, water and an organic binder and prepared by a vacuum clay kneader, and then fired. A method of manufacturing a ceramics sintered body, comprising: 2. Water and an organic binder are obtained from a compact obtained by compression molding using a kneaded clay containing a ceramic powder, a sintering aid, water and a heat gel-curable organic binder prepared by a vacuum clay kneader. A method for producing a ceramics sintered body, which comprises removing and then firing. 3. Water and an organic binder are transferred from a molded body obtained by transfer molding using a kneaded material containing a ceramic powder, a sintering aid, water and a heat gel-curable organic binder prepared by a vacuum clay kneader. A method for producing a ceramics sintered body, which comprises removing and then firing. 4. The method for producing a ceramic sintered body according to claim 1, 2 or 3, wherein the ceramic powder is within the range of the following formula. 5. The organic binder is a thermogel curable one, and the kneading is performed in a molding die in a range of (T-10) ° C. to (T + 25) ° C. with respect to a thermal gel curing temperature T of the organic binder. The method for producing a ceramics sintered body according to claim 1, wherein the soil is hardened by heat gel and molded. 6. The kneaded clay is heat-gel-hardened and molded in a mold having a temperature range of (T-10) ° C. to (T + 25) ° C. with respect to the heat-gel hardening temperature T of the organic binder. 4. The method for producing a ceramics sintered body according to any one of 4 above. 7. The water contained in the kneaded clay is 10 to 50 parts by weight based on 100 parts by weight of the ceramic powder, and the organic binder contained in the kneaded clay is based on 100 parts by weight of the ceramic powder. The method for producing a ceramics sintered body according to claim 1, wherein the amount is 0.1 to 15 parts by weight.