JPH0313194B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention relates to a silicon carbide fiber-reinforced silicon carbide composite suitable as a high-strength, high-toughness ceramic material used under high temperatures such as turbine blades for ceramic gas turbine engines. This relates to a method of manufacturing a body.

Prior Art Silicon carbide is attracting attention as a high-temperature structural material because of its excellent high-temperature strength. However, when used as a structural material, this material has the fatal drawback of being brittle. That is, once a crack occurs in this sintered body, the crack propagates throughout the body and causes destruction, making it unusable.
This is due to the low surface energy of the silicon carbide sintered body, so it can be improved by increasing the surface energy by making it composite. By the way, in general, when compounding, the materials introduced for reinforcement are those that have good affinity with the material forming the matrix and also have approximately the same coefficient of thermal expansion in order to suppress the generation of internal strain due to heat. It is necessary to choose. The easiest way to satisfy these conditions is to introduce the same substance to form the reinforcing phase and the matrix.

Regarding silicon carbide, there are two types of silicon carbide sintered bodies reinforced with silicon carbide whiskers (Preliminary Papers of the Basic Ceramics Forum, published in January 1985), and silicon carbide composites reinforced with silicon carbide fibers ( JP-A-57-135776) has been proposed, but the latter is more advantageous in terms of improving strength and preventing crack propagation.

By the way, until now, silicon carbide fiber-reinforced silicon carbide composites have been formed by adding a carbon-containing binder to pre-formed silicon carbide fibers, thermally decomposing the binder in a non-oxidizing atmosphere, and then impregnating molten silicon. It is manufactured by a method of heating and reacting (Japanese Patent Application Laid-open No. 135776/1983).

However, in this method, it is necessary to first produce silicon carbide fibers and use them as a raw material, but silicon carbide has difficulty in moldability and it is difficult to obtain the fibers on a mass production scale.

Problems to be Solved by the Invention The present invention aims to manufacture silicon carbide fiber-reinforced silicon carbide composites using easily available raw materials, which has been difficult to mass produce due to the availability of raw materials. This was done with the aim of providing a new method for doing so.

Means for Solving the Problems As a result of intensive research to develop a method for manufacturing reinforced silicon carbide composites using easily available raw materials, the inventors discovered that they could mold carbon fibers using carbon fibers as raw materials. We discovered that this purpose could be achieved by reacting silicon with silicon after processing.
Based on this knowledge, the present invention was made.

That is, in this invention, a carbon fiber molded body is impregnated with a thermosetting resin containing silicon carbide, and after curing treatment, the resin is heated to about 1000°C in an inert atmosphere to carbonize the resin and form carbon fibers and carbon. Provided is a method for producing a silicon carbide fiber-reinforced silicon carbide composite, which comprises forming a composite with silicon carbide, infiltrating the composite with molten silicon, and then heating the composite to 1450°C or higher in an inert atmosphere. It is something to do.

The carbon fiber molded article used in the method of the present invention includes cloth, three-dimensional fabric, and laminates of commonly available carbon fibers knitted or woven. The thermosetting resin to be impregnated into these molded bodies can be arbitrarily selected from commonly used thermosetting resins such as phenolic resins, epoxy resins, and furan resins.

In the method of the present invention, silicon carbide is blended with the thermosetting resin, and the appropriate amount is in the range of 10 to 30% by weight. The carbon fiber molded body impregnated with this thermosetting resin is then subjected to a curing treatment, and this curing treatment is performed using a curing agent commonly used for the thermosetting resin used at room temperature or It is carried out at temperatures in the range of °C. After the curing process is completed, the cured molded body is heated to about 1000° C. in an inert atmosphere to carbonize the cured resin. As the inert atmosphere at this time, a gas that does not react with each component constituting the cured molded product, such as argon gas or neon gas, is used. In addition, the temperature increase rate at this time is 2~
A range of 10°C/min is suitable. This carbonization process forms a composite in which the interstices of the carbon fibers are filled with a mixture of carbon and silicon carbide.

Next, this composite is impregnated with molten and liquid silicon. The amount of silicon impregnated must be sufficient to convert the carbon in the composite to silicon carbide. Then, the composite impregnated with silicon in this way is further heated in an inert atmosphere.
For example, heating to 1450℃ or higher in argon gas,
Carbon and silicon in the complex react to change silicon carbide.

The composite thus obtained consists of silicon carbide and a small amount of elemental silicon.

Effects of the Invention According to the present invention, a silicon carbide fiber-reinforced silicon carbide composite can be manufactured using easily available carbon fiber as a raw material. The composite obtained in this way has high toughness because both the fiber part and the matrix part are made of the same silicon carbide, and also maintains high strength even at high temperatures. The formation of silicon carbide fibers provides better physical properties than conventional composites of this type.

Therefore, the composite obtained by the present invention is suitably used as a structural material for ceramic gas turbine engine turbine blades and the like.

Examples Next, the present invention will be explained in more detail with reference to examples.

Example About 1.6% by weight of a curing agent and about 20% by weight of β-SiC powder are added to furan resin and mixed well. Next, carbon fibers are immersed in this, the resin is sufficiently adhered to the surface of the carbon fibers, the fibers are wound onto a bobbin frame, and the furan resin is cured by heating to approximately 70°C. Next, this cured product is removed, and the temperature is raised to 1000°C at a rate of about 5°C/min in argon gas to carbonize the furan resin.

In this way, a composite is obtained in which the carbon fibers arranged in one direction are filled with a mixture of carbon and β-SiC.

The composite is then infiltrated with molten silicon and heated at 1550° C. for 3 hours in argon gas.
In this way, a silicon carbide fiber-reinforced silicon carbide composite containing β-SiC as a main component and a small amount of elemental silicon is obtained.

Claims (1)

[Claims] 1 A carbon fiber molded body is impregnated with a thermosetting resin containing silicon carbide, and after curing treatment, in an inert atmosphere,
The resin is carbonized by heating to approximately 1000°C to form a composite of carbon fibers, carbon, and silicon carbide, which is then impregnated with molten silicon, and then heated to 1450°C or higher in an inert atmosphere. A method for producing a silicon carbide fiber-reinforced silicon carbide composite, characterized in that: