JPS61158403A - Method of molding ceramic - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of forming a ceramic body before firing.

[Conventional technology]

Mechanical parts such as engines and gas turbines, structural members of chemical plants, etc. are often made of ceramic materials, which have higher heat resistance, corrosion resistance, wear resistance, and high strength and are lightweight compared to metal materials. It has come to be used.

However, many mechanical parts have complex three-dimensional structures, so it is necessary to form a raw ceramic body in advance using a rubber press method, a mold press method, etc., and then perform machining before and after firing to achieve the desired shape. They were manufacturing the shape of
It cannot be mass produced, and the product cost becomes extremely high.
This made it difficult to put ceramic mechanical parts into practical use.

Therefore, there is a casting method in which ceramic slurry is injected into a plaster mold and molded using the mold's buildup, and ceramic powder and organic matter are heated to high temperatures to form a fluid state with fluidity, and then metal molding is performed. Injection molding methods, in which materials are injected into a mold, have been conventionally used.

However, in the above casting method, a plaster mold is generally used, but there are countless pores in the plaster wall surface that forms the mold material.
Furthermore, since the pore diameter is relatively large, 1 to 2[beta], if ceramic raw material powder having a particle diameter of 1 micron or less is used, the axial hole of the mold will be clogged, and the life of the mold will be significantly shortened.

Furthermore, since a plaster mold is used, there is a limit to the dimensional accuracy of the mold itself, and as a result, the molded ceramic body itself has the disadvantage of not being able to achieve high precision, and furthermore, the mold itself is easily damaged and worn out. There were drawbacks.

On the other hand, in the injection molding method in which ceramic powder is press-fitted into a mold, fluidity cannot be obtained unless a large amount (20 to 30% by weight) of an organic substance is added to the ceramic powder. Moreover, after molding, it takes a very long time to remove the added organic matter, and furthermore, the green density of the obtained molded calcined body is 5% of the calcined body density.
Not only does it have many drawbacks, such as a low firing shrinkage rate of around 0%, a large degree of shrinkage during firing, and a large deformation rate at that time, but it also involves injecting a fluid mixture of ceramic and organic matter into the mold under high pressure. The nozzle of the injection device was also significantly worn, and the worn metal components were mixed into the ceramic raw material, resulting in disadvantages such as deterioration of the characteristics of the ceramic body after firing.

[Problems to be solved by the present invention]

In view of the above-mentioned drawbacks of the conventional ceramic molding method, the present invention uses a slurry similar to that used in casting molding, and instead of using a porous material such as plaster, a metal mold used in the conventional injection method is used. This is a ceramic molding method that uses a ceramic molding method to form a three-dimensional complex shape and obtain a high e-degree molded product without the need for a degreasing process.

〔Example〕

The gist of the ceramic molding method according to the present invention is to use an organic dispersant for ceramic powder as a raw material, create a slurry with water or an organic solvent, pour the slurry into a metal or resin mold, and then add it in advance. After cooling to below the melting point of the organic dispersant, it is demolded, the solvent is dried, and the raw (before baking)
A ceramic molded body is obtained.

The procedure in this case is roughly as follows.

L Add an organic dispersant to ceramic powder, and perform mill mixing or stirring at a temperature above the melting point of the dispersant to prepare a slurry.

2. By pouring the prepared slurry into a mold and cooling it, the dispersant added in advance solidifies, the dispersibility disappears, and the slurry solidifies. Drying at a temperature below the melting point for several hours causes the solvent to evaporate and solidification of the entire molded product progresses.

& Next, the temperature of the dried molded product is raised to completely remove the solvent and organic dispersant contained therein, thereby obtaining a molded product. In this case, by keeping the solvent at a temperature lower than the melting point of the organic dispersant for several hours, the solvent will evaporate, and even if the temperature is subsequently raised, the molded article will not melt (it will not turn into a slurry).゛[Example 1] ] Silicon nitride Si, aN4 (100 parts by weight), yttrium oxide Y20B (5% by weight), alumina AAl
1203C (5% by weight), mineral spirit (14% by weight) as a solvent, and one of the polyoxyethylene alkyl ether phosphates as an organic dispersant, trade name NIBLYSURF 219B, melting point 35.
3% by weight of C. and stirred with a stirrer at 36.degree. C. for 12 hours to prepare a slurry. The viscosity at this time was 5 using an E-type viscometer.
rpm and lO poise. The slurry thus prepared was injected into a mold preheated to 35-40°C, then kept at 15°C for 10-20 minutes, and the demolded molded product was vacuum-dried at 25°C for 5 hours. Next, the silicon nitride molded object was placed in a dryer at 40°C, and the temperature was gradually raised to 400°C.
A silicon nitride sintered body was obtained by firing at a temperature of 0° C. for 2 hours.

[Example 2] Silicon carbide SiC! (100M place) boron carbide B4
Add 04% by weight of C, 4% by weight of carbon C, 5% by weight of polyethylene glycol alkyl ether, and add 2% of mineral spirit (trade name: Turpent) to silicon carbide.
Add 4% by weight and make a slurry without heating. This slurry was injected into a synthetic resin mold, cooled to -5℃, removed from the mold, and the molded product was vacuum dried for 12 hours and then baked in an argon gas atmosphere at 2200℃ for 1 hour to obtain the desired shape. A sintered silicon carbide body was obtained. This sintered body had a density of 3.16 and a bending strength of 55 kg and 7 mm.

[Example 3] Zirconium oxide Zr○2 (100 parts by weight), yttrium oxide ¥203 & 8 mol%, polyoxyethylene Therefore, the mixing ratio of the organic dispersant used in the ceramic molding method of the present invention is 2.5 to 10%. Optimal.

[Effects of the present invention]

As described above, according to the present invention, at least one organic dispersant is added to ceramic raw material powder to prepare a ceramic slurry, and after pouring, the slurry is cooled to below the melting point of the organic dispersant used and solidified. By obtaining a ceramic molded product using the process, it is possible to easily mass-produce molded products with high precision and high density without going through a degreasing process for ceramic bodies with complex three-dimensional shapes. .

Claims (1)

[Claims] One or more organic dispersants are added to ceramic raw material powder to form a ceramic slurry, the ceramic slurry is poured into a mold, and after cooling to below the melting point of the organic dispersant, the mold is removed. Ceramic molding method.