JPS61266355A - Manufacture of sic 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 [Industrial Field of Application] The present invention relates to a method for manufacturing an 81C sintered body.

[Conventional technology]

SiC sintered bodies are attracting attention as engineering ceramics due to their heat resistance, high strength, corrosion resistance, high thermal conductivity, and wear resistance. In order to increase the density of SiC sintered bodies, the use of various additives and the adoption of pressure sintering methods have been considered.
In recent years, high-density SiC sintered bodies have been obtained also by atmospheric pressure atmosphere sintering methods. Such a Japanese IC sintered body is usually
A compact made by adding additives such as a sintering aid and a binder made of B, Aj%Be%C, and their compounds to submicron SiC powder is heated in an inert atmosphere in a vacuum for 1900 min.
Obtained by firing at -2200°C.

Conventionally, since SiC12 shaped bodies are fired at high temperatures as mentioned above, graphite material is used in the high temperature part of the firing furnace, and this shaped body is placed on a black metal stand and fired. Since this sintered body is fired at a high temperature of 200G to 2100°C, SiC decomposes and is highly reactive with other substances. In particular, in the above temperature range where densification progresses, the influence of contact between the molded body and the adjacent members cannot be ignored, resulting in variations in the sinterability of the molded body and deformation due to differences in shrinkage rate.
This will hinder compaction. We have tried to solve this problem by using such bedding materials. However, high temperature 800G-ggoo
When firing at 0.degree. C., there are problems in that the powder sticks to the powder of the same material and damages the molded product.

This invention was made to solve these problems, and aims to provide a method for manufacturing a SiC sintered body that is uniform, deformable, and dense because there is no reaction with the powder. Means for Solving the Problems] The method for manufacturing a SiC sintered body of the present invention includes a method for producing a SiC sintered body in a graphite layer.
A layer is formed, treated at high temperature in an inert atmosphere, and 5
ial! : A molded body containing SiC and a sintering aid is placed on a base obtained by forming a porous layer of carbon composite and sintered to obtain a SiC sintered body.

[Effect]

The base in this invention is also baked with a graphite layer,
The surface also has moderate undulations. Some decomposed carbon powder is also mixed in, which reduces the resistance to shrinkage of the molded body and increases the shrinkage rate during high-temperature firing without any reaction with the molded body.

〔Example〕

The base according to the embodiment of this invention is an IEIi base on a graphite base.
It is obtained by scattering C powder and heating it in vacuum at a high temperature of 3000 to ggoo C to decompose it to form a porous plate-like layer of a composite of SiC and carbon.

Moreover, this base can be used repeatedly and is economically efficient. FIG. 1 is a sectional view showing a state during sintering according to an embodiment of the present invention. In the figure, +11 is a graphite layer, I!
l tI′i barb-shaped body, (31 is the base; that is, the molded body fil ij, ff-EI with an average grain size of 0.8.un
IO powder, 2-Oit% of boron carbide jI (B10) powder with an average particle size of 2 m, 1.5% by weight of amorphous carbon powder, and 4.0% by weight of oleic acid with alcohol added were all mixed together and dried. It was obtained by post-granulation and mold pressing and isostatic pressing (B ton A-d) to obtain an outer diameter of 80a1 and a thickness of 5U. Next, this molded body (2) has a graphite layer I.
The S1C sintered body according to an embodiment of the present invention was obtained by placing the S1C sintered body on top of N via the base +S+ and firing at 2100° C. for one hour. The sintered life density of the sintered body thus obtained was 8.1
5 f /art, and the shrinkage percentage measured from the dimensional change in the outer diameter is shown in the table.

Figure 2 is a cross-sectional view of a comparative example during sintering, and the molded body +21
The firing temperature and time were the same as in the above examples, but the firing conditions were varied. That is, in Fig. 2 (&1 is when the molded body (21t-) is placed directly on the graphite layer 111, in Fig. 8 (bl is 81
When G powder (41) is placed, Fig. 2 i01 is the graphite layer Il.
This is the case where the entire amount of carbon powder (5) was present between + and the molded body (2). According to the report, in these cases, if the molded body is placed directly on the graphite layer, the shrinkage rate on the side in contact with the graphite layer will be low, resulting in deformation, reaction and seizure. Even when Song is placed (Figure 8 (b;) reaction is significant, densification is hindered, and carbon powder is placed (Figure 8 10)), densification is low - 0 or less with 4 line margins. From the above, it can be seen that the SiC sintered body according to one embodiment of the present invention has a large shrinkage rate and is dense, and this tendency was also observed in other embodiments. As explained above, the invention is based on the graphite layer provided with 5i (3 layers), treated at high temperature in an inert atmosphere, and formed with SiO on the graphite layer.
On the base obtained by forming a porous layer of a composite of S and carbon,
By placing a molded body containing iC and a sintering aid on the molded body and firing it, it is possible to obtain a method for producing a uniform, undeformed, and dense SiC sintered body since there is no reaction with the bedding material.

[Brief explanation of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a sectional view of a comparative example. In the figure, fil tfi graphite layer, 12: molded body,
(3) is the base. In addition, the same symbols in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] A SiC layer is provided on the graphite layer, and a porous layer of a composite of SiC and carbon is formed on the graphite layer by high temperature treatment in an inert atmosphere. A method for producing a SiC sintered body, in which a molded body is placed and fired to obtain a SiC sintered body.