JPS59184773A - Manufacture of silicon carbide sintered 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 The present invention relates to a method for producing a silicon carbide sintered body mainly having a complicated shape, which is obtained by bonding and firing a plurality of molded bodies.

Usually, silicon carbide sintered bodies are made by molding silicon carbide raw powder into a predetermined shape using molding methods such as die molding, rubber press molding, slurry casting molding, and injection molding, followed by cutting when necessary. It is manufactured by post-drying and firing. In the case of a sintered body with a complicated shape, it is necessary to use a slurry casting method, an injection molding method, etc.; It is difficult to handle due to its weak body (LJI), and has disadvantages such as a prolonged drying process and a decrease in dimensional accuracy, which is not desirable. Further, in the case of the rubber press molding method, processing of the molded body after molding is required, which is troublesome.

On the other hand, when a molding method is used, the strength of the molded product is relatively large because there are few evaporated components, and the molded product is easy to handle, which is a preferable method.

Currently, there is a drawback that only relatively simple shapes such as cylindrical and plate shapes can be formed.

The present invention has been made to solve the above problems, and its main purpose is to provide an easy method for manufacturing a silicon carbide sintered body having a complicated shape.

In the present invention, a plurality of molded bodies formed by molding silicon carbide raw material powder using a mold are bonded together after applying an organic substance or a bonding agent consisting of an organic substance and the above-mentioned raw material powder.

The present invention relates to a method for producing a silicon carbide sintered body which is then fired.

The organic material used as the binder for joining the molded bodies in the present invention is not limited as long as it has adhesive strength, but it is preferable to use a composition that does not mix foreign matter into the sintered body.2 Usually, as an organic binder, known P
VA (polyvinyl alcohol), MC (methyl cellulose), CMC (carboxyl methyl cellulose), etc. are used.

It is also possible to bond the molded bodies together using a single organic substance (usually used as an aqueous solution) as described above.

Although it is possible to obtain a sintered body that satisfies the adhesive strength by firing, the use of a binder made by mixing an appropriate amount of the raw material powder of silicon carbide used in the molded body with the above-mentioned organic substance will reduce the adhesive strength of the sintered body. It is preferable that it can be increased to some extent.

In addition, when joining the molded bodies to each other, it is preferable to apply an appropriate amount of the above-mentioned binder to the joint surfaces and press the molded bodies together with a pressure of about 97 cm<2> to ensure a strong joint.

The silicon carbide raw material powder in the present invention is α type.

A mixture of β-type silicon carbide fine powder and powders of carbon, boron, beryllium, aluminum, or these compounds that act as sintering aids, or a powder made by granulating this mixture to make it easier to mold. , created by known means. The molding is performed, for example, by a known compression method using a mold whose surface has been hardened. The molded body after joining is
Sintering is performed at a temperature of 2,000 to 2,300° C. in vacuum or in a non-oxidizing atmosphere by a known so-called pressureless sintering method.

The present invention will be explained below with reference to Examples.

9 parts by weight of αSiC powder 99 powder with an average particle size of 0.5 μm.

1 part by weight of B, C (boron carbide) powder with a diameter of 5 μm.

0.5 after mixing 6 parts by weight of novolac type phenol resin
% by weight of PVA aqueous solution 150! The raw material powder of silicon carbide, which is obtained by adding a certain amount to a slurry, spray-drying it, and granulating it, is compressed with a pressure of 1000 kg/cm2 in separate molds (not shown) to form a box-shaped molded body as shown in Fig. 1. A rectangular block molded body 2 shown in FIGS. 1 and 2 was formed.

Next, make an aqueous solution containing 10i of PVA or MC,
These aqueous solutions of the binder 3 alone and the binder 3 containing the silicon carbide raw material powder in an amount of 30, 50, and 70.90% by weight relative to these aqueous solutions were applied to the side surface 1a of the box-forming body shown in FIG. On the coated surface, apply 4 kg 7 cm of l1111 side 2a of the rectangular block molded body 2 shown in Fig. 2.
2 (D Pressure ML Figure 3 VC shown f joined body 4ff
: Formed. Next, the above-mentioned joined body 4 was placed in a batch furnace and heated to 1200°C with a temperature increase of 250'C/h in a vacuum of 1 Torr or less.
'C, then fired in an argon gas atmosphere to 21
A silicon carbide sintered body was obtained by firing to 00'C.

Table 1 shows the bending strength of the bonded surfaces of the sintered bodies using various binders.

Table 1 All of the values of bending strength shown in Table 1 exceed the practically necessary value of Ruru 25, 7 m2, so any binder may be used, but the raw material powder content is 70 m2. 9Q
In the case of heavy loads, there is a tendency for the bending strength to decrease.

This is because the above-mentioned binders tend to become granular than in other cases.
This is thought to be because it is somewhat difficult to uniformly coat the bonding surface.

As described above, according to the present invention, a silicon carbide sintered body with sufficient bonding strength can be formed by bonding a plurality of silicon carbide molded bodies by molding with a binder and firing them. The present invention has the advantage that a silicon carbide sintered body having a good shape and good dimensional accuracy can be manufactured easily and at low cost.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a silicon carbide box-shaped body, and FIG. 2 is a perspective view of a silicon carbide square block molded body. FIG. 3 is a perspective view of a joined body obtained by joining the molded bodies of FIGS. 1 and 2. Explanation of symbols 1...Box-forming body 1a...Side surface 2...
Square block molded body 2a...Side surface 3...Binder 3 Figure

Claims (1)

[Claims] 1. Silicon carbide sintering, characterized in that a plurality of molded bodies formed by molding silicon carbide raw powder in a mold are bonded together after applying an organic substance or a binder consisting of an organic substance and the above-mentioned raw material powder, and then sintered. Method for producing solids.