JPS60118664A - Dewaxing agent for ceramic injection formation - 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] 〔Technical field〕 The present invention relates to a degreasing material for ceramic injection molding.

[Prior art]

Injection molding is used as a method for mass producing ceramic structures. Injection molding was originally developed as a type of plastic molding method, in which the molding material is heated and melted in the injection cylinder of an injection molding machine, and then the fluidized molding material is inserted into a mold tightly closed by an injection plunger. It is injected into a mold cavity to completely fill it, and then cooled and solidified or hardened to form a molded product.

In manufacturing a ceramic structure, first, ceramic powder is mixed with an organic binder, and this is then injection molded to form a ceramic injection molded body of a predetermined shape. Next, a degreasing treatment is performed to cause organic components to flow out and scatter from the ceramic injection molded body, and then sintering is performed by heating to a predetermined temperature to obtain a desired ceramic structure.

By the way, in the manufacturing process of the above ceramic structure,
Degreasing is an important process, and is usually carried out by placing the ceramic injection molded body in a degreasing furnace in an inert atmosphere. At this time, 4! from the ceramic injection molded body!
A degreasing material (pad material) is sometimes used to help drain and scatter organic components such as 1 fat. This degreasing material is usually made of a porous ceramic material and assists in the smooth removal of organic components from the ceramic injection molded body.

Conventionally, as such degreasing materials, commercially available particle sizes of 0.1μ to 1O
A fine-grained degreasing material with a grain size of 1.10 to 1000 μm is used.

By the way, when degreasing is performed while a ceramic injection molded body is embedded in a fine degreasing material, as schematically shown in Fig. A region A rich in organic components (organic component rich region) is formed near one surface, and a region B rich in organic components (organic component poor region) is formed around it.

When this organic component rich region A is formed, it becomes difficult for the organic components of the ceramic injection molded body 1 to flow out, and cracks, blisters, etc. may occur due to partial pressure differences and the like. This tendency becomes remarkable when the ceramic injection molded body 1 is thick or has a complicated shape.

Furthermore, when degreasing is performed while the ceramic injection molded body 1 is buried in a coarse degreasing material, the organic components flowing out from the ceramic injection molded body 1 are transferred to the organic component lynch region, as schematically shown in FIG. and an organic component poor region B is formed. 1st
The difference from the figure is that the organic component rich region A is narrower and has a higher density. In this case as well, the outflow of organic components within the ceramic injection molded body 1 is inhibited, and the above-mentioned defects are likely to occur.

From the above, in order to perform degreasing without causing defects,
It is understood that it is necessary that the organic component rich region A not be formed, and it has been desired to develop a degreasing material that satisfies this condition.

[Purpose of the invention]

The present invention has been made to solve the problems of the prior art described above.
? An object of the present invention is to provide a degreasing material for ceramic injection molding that can promote the flow and scattering of F'; and obtain a defect-free ceramic degreased body.

[Structure of the invention]

According to the present invention, such a purpose is to provide a degreasing material made of a ceramic material with a particle size of 50μ to 2000μ, which has an aggregate structure in which fine particles with a particle size of 0.1μ to 100μ are gathered together. This is achieved by a degreasing material for ceramic injection molding characterized by the following.

In the present invention, the materials for the degreasing material for ceramic injection molding include nitrides such as silicon nitride ('Si)N4), aluminum nitride (AIN), and boron nitride (BN);
Carbides such as silicon carbide (SiC) and titanium carbide (Tic), alumina (Al2O2), zirconia (ZrO2)
, titanium oxide (TiO2), oxide oxide
Oxides such as O), borides such as titanium boride (TiB 2 ) and zirconium boride (ZrBa), oxynitrides such as Sialon, activated carbon, and the like can be used. At this time,
It is desirable to use the same or similar ceramic material that constitutes the ceramic injection molded body.

In the present invention, the particle size of the degreasing material for ceramic injection molding is preferably 50 μm to 200,011 μm.

In addition, this degreasing material for ceramic injection molding with a particle size of 50μ to 2000μ has a particle size of 0, which is much smaller than the particle size.
．． It is necessary that primary particles of 1 μm to 10.0 μm form a so-called aggregate structure, in which the primary particles are firmly bonded together while retaining much of their original shape.

As a method for producing a degreasing material for ceramic injection molding having such an aggregate structure, as shown in FIG.
．． Primary particles 2 of 1 μ to 100 μ are placed in a 0.1 to 0.3% polyvinyl alcohol solution 3, stirred thoroughly, and then put into a spray dryer device 4 for granulation (spray dryer method). As shown in Fig. 4, water is added to primary particles 2 of 0.1 μm to 1000 μm, granulated while rotating, particles with a diameter of 50 μm to 2000 μm are taken out with a sieve 6, and granulated in a dryer 7. 100~200℃
It may be dried for 10 to 20 hours (sieve method).

[Operation of the Invention] The degreasing material for ceramic injection molding of the present invention has an appropriate particle size and has a large number of pores formed inside, so that organic components flowing out from inside the ceramic injection molded body are removed. flows out and scatters without remaining on the surface of the ceramic injection molded body and forming an organic component-rich region. Therefore, the organic components inside the ceramic injection molded body are not prevented from flowing out, and smooth degreasing is performed.

〔Effect of the invention〕

According to the degreasing material for ceramic injection molding according to the present invention, the voids between the particles of the degreasing material and the porosity inside the degreasing material are maintained at an appropriate level, so there is no formation of an organic component layer and a smooth organic component. spills and scatters. Therefore, defects such as cracks and blisters that occur during degreasing no longer occur, and a healthy ceramic degreased body can be obtained.

〔Example〕

Next, examples of the present invention will be described.

(First Example) 100 parts of silicon nitride powder with an average particle size of 0.9 to 1.0μ, 10 parts of polyethylene, 12 parts of ethyl vinyl alcohol
parts, 3 parts of dioxyphenylene as a plasticizer to 180±
After immersing it in a kneader set at 5℃ and stirring for about 40 minutes,
It was taken out from the kneader and coarsely powdered using a pelletizer. Next, the coarsely powdered pellets were put into a twin-screw extruder set at 140±2° C., and extrusion was performed at 100 cc/min with a downward feeder to produce pellets for injection molding. after that,
The pulley was injection molded using an injection molding machine at an injection temperature of 180°C, a mold temperature of 50°C, an injection pressure of 900 kg/cm, and an injection rate of 40 cc/sec.

Next, this injection molded body was placed in a degreasing furnace, and a degreasing material was further filled around the injection molded body. At this time, the primary particles of the degreasing material were silicon nitride powder with an average particle size of 1μ (showing a particle size distribution in the range of 0.1 to 10μ), and the particles were made into particles of 1.1100μ to 400μ using the above-mentioned spray dryer method. I used something. Next, the inside of the degreasing furnace is heated to 50°C to 50°C.
Degreasing was performed by raising the temperature to 0°C at a rate of 4°C/hr. After that, 1750°C in a 1 atm nitrogen gas atmosphere.
Calcination was carried out at ℃.

The yield rate of pulleys made of silicon nitride obtained as a result was investigated. As shown in Fig. 5, this good product rate is
, internal defect 3, inner peripheral defect 4, and overall were investigated. The results are shown in Table 1.

(Second Example) As a degreasing material, silicon nitride powder with an average particle size of 1μ (showing a particle size distribution in the range of 0.1μ to 10μ) was used as the primary particle,
A pulley was manufactured under exactly the same conditions as in Example 1, except that particles having a particle size of 100 μm to 400 it were used using the sieve method described above. The yield rate of the pulleys obtained as a result is shown in Table 1 as in the first example.

(First Comparative Example) A pulley was manufactured under exactly the same conditions as in the first example, except that silicon nitride fine powder with an average particle size of 1μ (showing a particle size distribution in the range of 0.1μ to 10μ) was used as the degreasing material. was manufactured. The yield rate of the pulleys obtained as a result is shown in Table 1 as in the first example.

(Second Comparative Example) As a degreasing material, the average particle size is 300μ (100μ to 500μ).
A pulley was manufactured under exactly the same conditions as in Example 1, except that silicon nitride coarse powder having a particle size distribution of μ was used. The resulting boo! The good product rate of J is shown in Table 1 as in the first example.

Table 1: Firing good product rate (N-100) for each degreasing material 1st
As is clear from the table, when degreasing is performed using the degreasing material for ceramic injection molding according to the present invention, the yield rate is significantly improved compared to when conventional degreasing materials are used. .

[Brief explanation of the drawing]

Figure 1 is a schematic configuration diagram schematically showing the concentration ratio of organic components when degreasing using a conventional fine-grain degreaser, and Figure 2 shows the result when a conventional fine-grain degreaser is degreased with A schematic configuration diagram schematically showing the concentration ratio of organic components; FIG. 3 shows an outline of the method for producing a degreasing material for ceramic injection molding according to the present invention; FIG. 4 is a process diagram according to the present invention. FIG. 5 is a process diagram showing an outline of another manufacturing method of a degreasing material for ceramic injection molding, and FIG. 5 is a schematic diagram showing each defect in a pulley manufactured in an example of the present invention. - Ceramic injection molded body A - Organic component lynch region B --- One organic component poor region 2 -- Primary particles 3 -- Polyvinyl alcohol solution 4-11 Spray dryer device 5 ---・Degreasing material 6-・Sieve 7--・Dryer 8--・External defect 9--m-・Internal defect 10-m-Inner circumferential defect Applicant: Toyota Automobile Co., Ltd. Figure 1, Figure 2 figure

Claims (1)

[Claims] (1) Particle size 50μ to 2000 made of ceramic material
A degreasing material for ceramic injection molding, characterized in that the degreasing material has a grain size of 0.1 to 100 microns and a fine grain structure to a clustered aggregate structure.