JPS5954676A - Manufacture of fiber reinforced 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 (a) Background and Technology The invention relates to a method for producing a heat-resistant ceramic sintered body, particularly a silicon carbide sintered body6.

Among heat-resistant ceramics, silicon carbide has particularly excellent heat resistance, heat resistance, and 1° corrosion resistance. This is an influential topic and is being pursued with great interest.

Resistance: Use of heat-resistant ceramic outer sintered bodies for these 11η construction moons.

For practical purposes, physical and chemical stability at high temperatures is required. In particular, high mechanical properties at high temperatures are desired.

However, silicon nitride and silicon carbide are both covalent compounds and are considered difficult to read binding materials.

Therefore, silicon nitride and silicon carbide are not sintered alone, but are added with several percent to several tens of percent of a sintering aid to form a low melting point compound and sintered.

For example, in the case of silicon carbide, Al is used as a sintering aid.

Dr B4CAl2O5 etc. alone or in combination of multiple π11.

Add 1 to 20% and use the pot press.

A sintered body with a density close to the theoretical density was obtained.
：” ”l□However, the sintered body obtained in this way is high? The intensity at fiλ is insufficient. □It was added as a sintering aid. A1
．． Although 203 and the like have the advantage of accelerating sintering by forming a low melting point compound as described above, the strength at high temperatures decreases due to this low melting point compound.

Since this J: □, consideration has been given to reducing the type of sintering aid and its ik as much as possible during the production of silicon nitride and silicon carbide sintered bodies, but the strength at high temperatures is The downside of the decline is that it has not been resolved in the end.
It looks like this.

In view of the present invention and the information set forth in Section 1.1. As a result of intensive studies to obtain sintered f4ζ with excellent TL properties and high-temperature strength, we have previously discovered a method for manufacturing silicon sintered 14 reinforced with fibers (ill-shaped whiskers) and have filed an application.

(Japanese Patent Application No. 5/1/1970 - January 4, 1971, and Japanese Patent Application No. 55/1982 22 i, + 3 υ') Whiskers are generally
It is a single-crystal fiber, also known as cat's whiskers, and is said to be tens to hundreds of times stronger than polycrystalline fibers.

Since this single crystal fiber was discovered, its applications have been widely considered as a dream material, but it has not yet been put to practical use.

2. The application by the inventors provides an industrially easy manufacturing method for dispersing these whiskers in a sintered body of silicon carbide. There are □ that give you a straight body.

The manufacturing method involves mixing whiskers during powder mixing and then press molding, so the whiskers are mixed unevenly. There was a problem that the strength of the sintered body differed depending on the direction because the sintered body was aligned only in a specific direction.

(B) Disclosure of the Invention The present invention provides a method for producing a silicon carbide sintered body, which has become a famous product, and which can eliminate all of the above-mentioned drawbacks and problems in addition to the characteristics of silicon carbide sintered bodies produced by conventional methods. The purpose of this invention is to improve the manufacturing method of silicon carbide whisker-strengthened silicon carbide sintered bodies.

In the prior art, in order to mix the ζ-fiber M11:-shaped whiskers and the granular raw material powder during powder mixing, "6-Mixing and Multi:l! , there was a drawback □ in which mixing was difficult. □ The present invention provides a new method to solve this problem in homogeneous mixing.' □Hereinafter,
The present invention will be described in detail.

Immediately □ Stop mixing the granular raw stone □ powder and sintering aid with the fibrous whiskers, and mix it with the raw material powder and sintering aid described in 1. The mixed powder was heated at 130% in a non-oxidizing atmosphere.
Heat treatment at a temperature of 0"C or higher, preferably 15'00-1.'? 50°C. 1. From this, alt + 1illJ-shaped whiskers are generated from the mixed granular whisker-forming agent. The powder is molded into a predetermined shape, heated, and heated to a non-acid 1.
By performing densification firing N-old under a normal atmosphere: Vlk
This is a method for producing a type of silicon carbide sintered body.

In the present invention, the raw material powder and sintering aid are not particularly limited, and generally known crystals, structures, and chemical compositions are sufficient. The whisker generation agent to be mixed may be any one that generates gaseous SiO in a non-oxidizing atmosphere, and the whiskers grow through this gaseous phase. The inventors have discovered that metal S + + Si, such as Si'02,
Inorganic compounds including silicone rubber, silicone resin;
one or more selected from the group consisting of organic compounds containing Si of the 1st class, and carbon and an organic substance that generates carbon by thermal decomposition J: a combination of one or more selected from the following groups; All of them were found to have similar effects as described above.

Hereinafter, the present invention will be explained in detail with reference to Examples.

Example SiC powder 74. 2% by weight of B and C powders are added as sintering aids to Tsumeuta%, and SiO as a whisker forming agent is added.
2 and C 20 tons each; enemy; 2%, 4・heavy::, %
The mixture was added and ground and mixed using a ball mill for 120 hours. This mixed powder was heated to 1550'C, IXJO-
After holding for 2 hours in a vacuum of ``Torr'' and heat-treating for whisker generation,
It was molded into a test piece for transverse rupture strength measurement by stamping n/1yn9. This adult body was heated to 2050'C in an argon atmosphere of 1 atm.
It was held for 1 hour (21 hours and densified sintered for 1 j hours).

Bending at 3 points with a 20 gate span, the transverse rupture strength is i11! The determined fracture surface was observed using SEM.

Same 51. Make it into a hill and add various whisker forming agents”C
Table 1 summarizes the constant results of the sintered test pieces after the whisker growth heat treatment.

For Table 1 Sugi 8' Mugishi Norihi 1, heat the mixed powder containing no whisker forming agent at 1550°C + 1. x ], heat treated in a vacuum of 0-3 Torr for 2 hours, molded into a mold, and held at 2050°C for 1 hour in an argon atmosphere F for 1 hour to perform densification sintering, as shown in Table 1. This is shown as Example 3.

The product obtained by the method of the present invention has a transverse rupture strength of 20% or more in the direction -1-
This shows that the effect of the present invention is high.

In addition, as shown in Comparative Example 2, when the amount of the whisker-forming agent is 1% by weight or less, the effect is i < , 7.
At 0 ton, +11H% or more, the strength decreases on the contrary. For this reason, it is judged that addition of the whisker forming agent in an amount of j to 70a is effective.

The whisker generation heat treatment temperature is 1300'C or lower, since whisker generation does not occur, so the heat treatment must be performed at 2!+a degrees above I300'C, but 1500'
At temperatures below -C, the whisker formation rate is slow, and 1
75 (because SiC grain growth occurs when the temperature exceeds 1"C.

J n (1 (1 to 1750°C)'(Ra degree range is considered preferable).

The fracture surface after measuring the transverse rupture strength of the sample of the present invention;
According to θL, the diameter is 1.1 (about m) and the length is 1.0-
It was confirmed that the fibers of 100 μm in diameter were three-dimensionally intertwined, and that the improvement in transverse rupture strength was due to this fiber strength type mechanism.

1 hJ Wis force - generation The heat treatment time is also related to the heat treatment temperature, but in the above temperature range, it is usually sufficient to set it to 0.5 hours or more. Since no particular effect was observed even after two treatments, we believe that a treatment time of 0.5 to 22 hours is sufficient.

Claims (1)

[Claims] (1) Silicon carbide rice crab is dispersed: A method for producing a silicon carbide sintered, compacted body, by carbonization, silicon, powder and heat treatment,
Whisker forming agent, whisker forming agent, and sintering aid are mixed together, and the resulting gold powder is heated under a non-acid, oxidizing mist atmosphere. After applying heat treatment to generate iscar, 1. ．． It is formed into a predetermined shape, and then densified and sintered in a non-oxidizing atmosphere. A method for producing a fiber-reinforced silicon carbide sintered body. (2. Lie, non-carrying, etc. as stated in claim 1)
One or more compounds selected from the group consisting of an inorganic compound containing the metal 5xtSi and a compound containing St, and carbon and 1 which generates carbon by thermal decomposition.
m organic matter, one or more selected from the group consisting of:
Fiber-reinforced silicon carbide sintered 14 This manufacturing method □ is characterized in that the total amount thereof is 1 to 70% by weight. (3) A method for producing a fiber-reinforced silicon carbide sintered body, characterized in that the whisker-forming heat treatment temperature according to claim 1 is 1300°C or more. , .