METHOD FOR PRODUCING SIC FIBER-REINFORCED SIC COMPOSITE MATERIAL HAVING EXCELLENT FRACTURE TOUGHNESS

摘要

A method for producing a SiC fiber-reinforced SiC composite material having excellent fracture toughness, which comprises incorporating fine SiC particles homogeneously into a polyvinyl silane having unit structures (a) and (b) at a (a)/(b) ratio of 1 in an amount of 50 to 70 mass %, to provide a homogeneous resin slurry, impregnating a SiC fiber formed product with the resin slurry, heating the resultant resin-impregnated SiC fiber formed product to a temperature of 300 to 400° in Argon gas atmosphere to thereby convert the polyvinyl silane to a high viscous liquid or a semi-solid, and then firing the resultant product at a temperature of 1000° or higher in an Argon gas atmosphere while pressuring uniaxially under 2 to 10 MPa. The method allows the relaxation of the inner stress in sintering, and provides a SiC fiber-reinforced SiC composite material which has a high density, exhibits a great work of fracture, and is excellent in mechanical properties and toughness. Further, the repeated impregnation with the polyvinyl silane alone and firing with no pressuring after the above firing provides a SiC fiber-reinforced SiC composite material having a further improved density and fracture toughness.