JPS62265180A - Method of dewaxing ceramic injection formed body - 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 for degreasing ceramic injection molded bodies in ceramic products used in electronic parts, automobile parts, and the like.

Conventional technology In recent years, ceramic application products are rapidly becoming automotive parts.

The fields of use are expanding to electronic parts, heat-resistant mechanical parts, wear-resistant parts, etc. For this reason, there is an increasing need for ceramic products to have more diverse and complex shapes.

Among these, so-called injection molding, in which a mixture of ceramic powder and organic matter is heated and melted and poured into a mold, is becoming widely adopted as a method for efficiently molding ceramic materials into desired shapes with high precision. . However, the injection molded product contains a large amount of the above-mentioned organic matter, and it is necessary to remove it, that is, degrease it, before firing.

Conventionally, as a degreasing method for this type of ceramic injection molded body, as shown in Japanese Patent Publication No. 59-39776, a ceramic injection molded product obtained by mixing ceramic powder and an organic substance and injection molding has been used. Molded object. There is a method of heating and degreasing under reduced pressure of 7 H7 or less.

Problems to be Solved by the Invention - However, in such a conventional configuration, the organic matter in the ceramic injection molded body is heated under reduced pressure, so it rapidly thermally decomposes, causing cracks and deformation, and After decomposition, organic matter remains in the molded body as carbon, which is oxidized during firing and reduces the ceramic, and there are problems in that siffrac occurs due to the generation of decomposed gas.

The present invention has been made in view of the above points, and an object of the present invention is to provide a method for degreasing a ceramic injection molded body that prevents deformation and cracking, does not generate residual carbon, and has a high manufacturing yield. There is.

Means for Solving the Problem In order to solve this problem, the present invention uses a mixed gas with an inert gas such as nitrogen or argon containing at least 1 srnol of oxygen when degreasing a ceramic injection molded body. The molding process is carried out under a pressure of 3 to 10 atm to prevent cracks, cracks, irregularities, deformation, and voids caused by residual carbonization of organic materials used in injection molding and rapid decomposition and combustion. It is something. As a result, the ceramic injection molded body is effectively degreased.

action The effect of this technical means is as follows.

That is, the organic matter that oozes out onto the surface of the ceramic injection molded body due to heating is gradually decomposed and scattered under pressure and removed, so that sudden evaporation or decomposition that occurs under reduced pressure does not occur. Further, residual carbon, which occurs due to insufficient scattering of organic substances that occurs in an inert atmosphere, does not occur because the treatment is performed in an oxygen atmosphere. As a result, good degreasing is possible without causing deformation, cracks, pores, or residual carbon during the degreasing process.

In addition, the reason why the pressurization was limited to 3 to IQ ILtm was 3! Below Ltm, rapid scattering and decomposition of organic matter will cause cycler I, while above 10 &tm, scattering of organic matter will be inhibited and sufficient degreasing will not be carried out. The reason why the oxygen concentration of the mixed gas of the pressure medium is set to 1 ts rno 1% or more is because if the oxygen concentration is less than 1 s mo 1%, the scattering and decomposition of organic matter is insufficient and residual carbon is generated.

EXAMPLE An example of the present invention will be shown below. First, a barium titanate-based semiconductor ceramic raw material with an average particle size of 1.2 μm was used as ceramic powder, 18.5 wt% of a thermoplastic resin consisting of polystyrene, atactic propylene, and paraffin was added thereto, and the mixture was kneaded at 2oO°C for 1 hour. Heat and knead in a 41111φX10 extrusion molding machine.
It was molded into m+ pellets. This pellet was injection molded using an injection molding machine at 180°C and 9800 kg/c1d to produce a ring-shaped ceramic injection molded body having an outer diameter of 15 mm, an inner diameter of 15 am, and a thickness of am.

Such a ceramic injection molded body was heated to 260"C at a heating rate of 8°C/hr using the gas composition and pressure shown in the table below, and then held at 260"C for 4 hours, and then injection molded. The polystyrene, atactic propylene and paraffin used in the process were removed by heating and degreased. After this, 1
Cooling was performed at a temperature decreasing rate of 00°C/hr. Note that the mixed gas continued to flow at a flow rate of 0.2 w/win during the degreasing process.

The surface and cut surfaces of the degreased molded product thus obtained were observed using a stereomicroscope for 3Q each to detect cracks.

The results of checking for abnormalities such as unevenness are also shown in the table below.

Next, this degreased molded body was heated at a heating rate of 200°C/hr.
The temperature was raised to 300@C, maintained at 1300''C for 1 hour, and then cooled at a rate of 100''C/hr to produce a sintered body.

This sintered body was used in the same manner as the degreased molded body, and the presence or absence of abnormalities was confirmed using a stereoscopic microscope.The results are also shown in the table below.

(The following is a margin) Here, 2/3o in the table indicates that cracks occurred inside two of the 30 elements or a defect occurred due to a defect such as unevenness on the surface. As is clear from the above table, it contains 1 smoe or more of oxygen and 3-1Q
Example according to the invention (sample N) degreased under pressure of ATM
a3+'+6), no defects were observed in either the degreased compact or the sintered compact.

On the other hand, in Examples other than those of the present invention, many defects occurred.

In this example, argon (Mr) was used as the pressurizing medium.
A mixed gas of nitrogen and oxygen was used, but nitrogen and helium (He
It goes without saying that similar effects can be obtained by using a mixed gas of oxygen and other inert gases such as ). Also,
Ceramic materials for the ceramic injection molded body that can be degreased by the method of the present invention include lead zirconate titanate, silicon nitride, silicon carbide, alumina, zirconia, etc. other than the barium titanate semiconductor ceramic shown in the examples of the present invention. A similar effect can be obtained even with ceramic materials.

Effects of the Invention As described above, according to the present invention, a ceramic injection molded body is prepared by using a mixed gas containing oxygen at 1 s mop 4 or more with an inert gas such as nitrogen gas or argon as a pressure medium.
By degreasing under pressure of 3 to IQ atm, it is possible to prevent the occurrence of defects such as deformation and cracks, and the unique effect of significantly improving the manufacturing yield can be obtained.

Claims (1)

[Claims] When degreasing ceramic injection molded products, 15 m of oxygen is used.
A method for degreasing a ceramic injection molded body, which is carried out under a pressure of 3 to 10 atm in a mixed gas with an inert gas such as nitrogen or argon containing ol% or more.