JPS6172677A - Dewaxing material for ceramic injection molding - 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 This invention relates to a degreasing material used to cause organic components to flow out and scatter from a ceramic injection molded body containing organic components as a binder.

Conventional technology As a method for mass producing ceramic parts.

Injection molding is used. Injection molding was originally developed as a type of plastic molding method, in which plastic molding material is heated and melted in the injection cylinder of an injection molding machine, and then the fluidized molding material is tightly closed in advance 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.

To manufacture ceramic parts, first, ceramic powder is mixed with an organic binder, and the mixture is injected into a mold to form a ceramic injection molded body of a predetermined shape. Next, the obtained ceramic injection molded body is subjected to a degreasing treatment to cause organic components to flow out and scatter, and then heated to a predetermined temperature and sintered to obtain a desired ceramic part.

By the way, in the manufacturing process of the above ceramic parts,
Degreasing is an important step, and is usually carried out by placing the ceramic injection molded body in a degreasing furnace and performing steps 1 to b in an inert atmosphere. At this time, a degreasing material (pad material) may be used to help drain and scatter organic components such as resin from the ceramic injection molded body. 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 the above-mentioned degreasing material, commercially available particle size 0.1μI11
~10μm fine degreasing material, or particle size 10μm~100
0μen coarse degreasing material is used.

Problems to be Solved by the Invention 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. These organic components form a region A rich in organic components (organic component rich region) near the surface of the ceramic injection molded body 1, and a region B rich in organic components (organic component poor region Te) around it.
, ). When this organic component rich region A is formed, it becomes difficult for the right eye component 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.

- On the other hand, when degreasing is performed while the ceramic injection molded body 1 is buried in a coarse degreasing material, as schematically shown in FIG. Region A and organic component poor W4 region B are formed, but compared to the case where fine degreasing material is used, the organic component rich region tii! A becomes narrower and its density becomes higher. 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.

Therefore, in order to perform degreasing without producing 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.

This invention was made in order to solve the above-mentioned problems of the prior art, and it is a ceramic injection molded body that promotes smooth outflow and scattering of organic components in a ceramic injection molded body and can obtain a defect-free ceramic degreased body. The purpose of this invention is to provide a degreasing material for molding.

Means for Solving the Problems In order to achieve the above object, the present invention has a particle size of 10μI.
I or more, and the porosity is 0.150C/g to 1.50C
This is a degreasing material for ceramic injection molding that is made of powder and granules with a structure that has micropores inside so that the ratio is G/g.

Specific Description for Carrying Out the Invention In this invention, silicon nitride is used as the material for the degreasing material for ceramic injection molding. (Si3N4), nitrides such as aluminum nitride (ΔQN), tsunium nitride (BN), silicon carbide (SiC), titanium carbide (TiC), alumina (^1!203), zirconia (Zr02),
Brewing Ch') N (Ti O2>, m (HiJ<!J
Oxides such as ram (8a O), titanium boride (TiB2)
), 1 compound such as zirconium tsuride Rr82), 2M compound such as Sialon, activated carbon, etc. can be used. At this time, it is desirable to use the same material or similar material to the ceramic material constituting the ceramic injection molded body.

In addition, the porosity of the degreasing material for ceramic injection molding in this invention is 0.15cc/l to 1.5Qcc/! J
is good, preferably 0.3cc, /g~1°QCC/!
].

Furthermore, as a method for manufacturing a degreasing material for ceramic injection molding having the above structure, as shown in the outline in FIGS. The so-called spray dryer method, in which the degreasing material 5 is obtained by adding 0.1 to 0.3% polyvinyl alcohol solution 3 and sufficiently stirring the mixture, and then inputting the kneading force into the spray dryer device 4 to granulate the degreasing material 5, As shown in Figure 4, a so-called sieve method is adopted in which water is added to ceramic powder 2 of the same particle size, stirred and mixed, granulated while rotating through a sieve 6, and then dried in a drier 7. can do. In addition, the porosity of 1 m in these methods depends on the concentration of the polyvinyl alcohol solution, the particle size of the ceramic powder, and the rotation time of the sieve. It is possible to set 4.

That is, FIGS. 5 and 6 are q diagrams showing the porosity of the degreasing materials obtained by the present inventor by granulation using the above-mentioned methods.
．． In the case of granulation using a spray dryer method using a 2% polyvinyl alcohol solution, as shown in FIG. 5, the smaller the particle size of the ceramic powder used as the raw material, the lower the porosity. Further, when ceramic powder having an average particle diameter of 1.2 μm is used as a raw material and granulated by a sieve method, the porosity decreases as the sieve rotation time increases, as shown in FIG.

Function: The degreasing material for ceramic injection molding of the present invention has an appropriate particle size and has a large number of micropores formed inside, so that the organic components flowing out from inside the ceramic injection molding can be removed from the ceramic injection molding material. It flows out and scatters without staying on the surface of the molded product 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.

Example Examples of the present invention will be shown below along with comparative examples.

...11 The ceramic injection molded body to be subjected to the drawing work was created as follows. First, 180 parts of polyethylene, 12 parts of ethyl vinyl alcohol, and 3 parts of dioxyphenylene as a plasticizer were added to 100 parts of silicon nitride powder with an average particle size of 0.9 to 1.0 μm in a kneader set at 5°C. Add, 40
After stirring for about a minute, the mixture was taken out from the kneader and coarsely powdered using a pelletizer. Next, this coarsely powdered pellet was
Place the tube in a twin-screw extrusion chamber set at 2°C, and
Extrusion was carried out at a feed rate of Co/min to produce Belene 1- for injection molding. After that, the injection temperature [1
180℃, mold temperature 50℃, injection pressure 900 ko/a
A pulley having the cross-sectional shape shown in FIG. 7 was injection molded at an injection rate of 140 cc/sec.

In addition, as a degreasing material, the above-mentioned spray dryer method is used to produce particles with an average particle size of 10 μm or more and a porosity of 0.5 CC.
Ceramic powder particles adjusted to 1.03 cc/g and 1.03 cc/g were used.

In the degreasing process, the injection molded article is placed in a degreasing furnace, the surroundings thereof are filled with each of the degreasing materials described above, and then the temperature inside the degreasing furnace is raised from 50°C to 500°C at a rate of 4°C/hr. Then, the oil was removed. Thereafter, firing was performed at 1750° C. in a nitrogen gas atmosphere of 1 atm.

The yield rate of the silicon nitride bollies thus obtained was investigated. As shown in Figure 7, this non-defective rate is due to external holes! 4
i8, internal defect 9, inner peripheral defect 10. We investigated four overall points. The results are shown in Table 1 as actual drawings.

Example ■ Average particle size 10 um created by the sieve method described above
The above degreasing materials were used. Its porosity is 0.15cc
/IJ, 0.31ce/a, Ryohi 0.42cc/g
No. 31, each of which was subjected to degreasing and firing treatments in the same manner as in the above-mentioned construction work, and the yield rate of the resulting bulges was examined. The results are shown in Table 1 as Example (2).

Average particle size is 300 μl as a comparison degreasing material! Using silicon nitride coarse powder (with a particle size distribution of 100 μm to 500 μm), the other conditions were the same as in the above-mentioned drawing process, and the nine processes of removal and firing were performed to obtain a pulley.
We investigated the non-defective product rate. The results are shown in Table 1 as Comparative Example IE.

Comparative example ■ As a degreasing material, the average particle size is 0.4 μm (0.3 to 0
．． Fine silicon nitride powder (with a particle size distribution of 5 μm) was kneaded in a 13% polyvinylic alcohol solution, and this was granulated by a sieve method to obtain 1.48 CC10 and 1.83 CC/
A material whose porosity was adjusted to that of CI was used. The other conditions were the same as in Example 2 of Kouki, and the treatments of fat removal and firing were carried out, and the yield rate of the resulting pulleys was examined. The result is the first
Comparative example ■ is shown in the table.

Table 1 (N=100) Firing good product rate (%) Manufacturing method Porosity External defects Internal defects Inner circumferential defects Overall (CC/U) None None
No example spray dryer 0.50 9
8 100 98 981.03 94
96 95 930.15 92
96 95 91: Ura Example ■ Sieve 0.31
98 99 97 960.42 99 100
99 99: Bite Spray Dryer 0.
10 3 16 56 1; Comparative example■
Sieve 1.48 93 83 81 78 As is clear from the results shown in Table 1, according to the degreasing material of the present invention, the yield rate of fired products is extremely high and it is possible to obtain ceramic degreased bodies without defects. Effects of the Invention As is clear from the above explanation, the degreasing material for ceramic injection molding of the present invention (according to the degreasing material of the present invention, the voids between the particles of the degreasing material and the microporosity inside the degreasing material are maintained optimally, There is no formation of a barred component-rich region, and smooth outflow and scattering of the barbed component occurs.Therefore, cracks that occur in the IJ during degreasing,
Defects such as blisters do not occur, and a healthy ceramic degreased body can be obtained.

[Brief explanation of drawings]

Figure 1 is a schematic diagram schematically showing the haze ratio of organic components when degreased using conventional fine-grain n-greasing material, and Figure 2 is a diagram schematically showing the haze ratio of organic components when degreased using conventional PI degreasing material. The presence of one component in combination!
f! ! Figure 3 <a)
~(C) are process diagrams schematically showing the manufacturing process of the degreasing material for ceramic injection molding according to the present invention, and FIGS. 4(a) to (d)
＞ is a process diagram schematically showing another manufacturing process of the degreasing material for ceramic injection molding according to the present invention, and FIG. 5 is a diagram showing the relationship between the porosity of the spray dryer method and the particle size of the ceramic powder used as the raw material. , FIG. 6 is a scale diagram showing the relationship between the porosity and the rotation time of the sieve according to the sieving method, and FIG. 7 is a schematic diagram showing the cross-sectional shape and defects of the bore, which is the test material. 1... Ceramic injection molded body, 5... Degreasing material.

Claims (1)

[Claims] Average particle size is 10μm or more and porosity is 0.15cc
A degreasing material for ceramic injection molding consisting of porous granular material of /g to 1.50cc/g.