Process for producing fiber-reinforced-silicon carbide composites

Abstract

A process produces a fiber-reinforced silicon carbide composite. The resulting composite has a high toughness where bundles of a reinforcing fiber are densely covered with glassy carbon derived from a resin to avoid deterioration of the strength, and it can easily be produced even in complicated shapes. Specifically, a fiber-reinforced silicon carbide composite is produced by preparing a fiber prepreg containing a powdered silicon and a resin and molding the prepreg to yield a green body having a desired shape, or laminating a fiber prepreg containing a resin and a woven fabric prepreg containing a powdered silicon and a resin in alternate order, and molding the laminate to yield a green body having a desired shape; carbonizing the green body at 900° C. to 1350° C. in an inert atmosphere; impregnating the carbonized body with a resin; firing the impregnated body again at 900° C. to 1350° C. in an inert atmosphere; performing the resin impregnation-carbonization procedure one to five times; subjecting the carbonized composite to reaction sintering at a temperature of 1300° C. or more in vacuo or in an inert atmosphere to form open pores, and finally infiltrating molten silicon into the sintered body having open pores at a temperature of about 1300° C. to 1800° C. in vacuo or in an inert atmosphere.