Abstract: A mixed polymer liquid is prepared by mixing a polycarbosilane-dissolved organic solvent with poly(methylsilane) and moderated to viscosity of 5–20 Pa·s by heat-treatment to promote partial cross-linking reaction. The mixed-polymer is then melt-spun to fiber at 250–350° C. The fiber is cured by treatment at 100–200° C. in an oxidizing atmosphere, and baked at 1000° C. or higher. Due to thermosetting action of poly(methylsilane), the mixed polymer liquid is continuously melt-spun without breakage, and SiC fiber produced in this way is useful for reinforcement of SiC composite excellent in toughness, strength and heat-resistance.

Abstract: A preformed of SiC fiber, which is coated with one or more of C, BN and SiC, is impregnated with a slurry, which suspends fine SiC powder and a sintering additive therein. The impregnated preform is hot-pressed at 1600-1800° C. with a pressure of 10 MPa or more. The sintering additive may be one or more of Al2O3, Y2O3, SiO2 and CaO. The slurry may futher contain a silicone polymer selected from polycarbosilane, polyvinylsilane and polymethylsilane. Reaction of SiC fiber with a matrix is inhibited by the coating, so as to manufacture a SiC fiber-reinforced SiC-matrix composite remarkably improved in mechanical properties.

Abstract: A powdery mixture of fine SiC powder with one or more oxide sintering additives of Al2O3, Y2O3, SiO2 and CaO is blended and uniformly dispersed in a polymeric SiC precursor to prepare a matrix-forming polymeric slurry. A preform of SiC fiber, which has quasi-stoichiometric composition with high crystallinity, is impregnated with the polymeric slurry and then hot-pressed at a temperature of 1600° C. or higher in presence of a liquid phase. Since the heat-resistant SiC fiber is used as strengthening fiber, the prepreg is sintered to a dense SiC composite excellent in mechanical properties by one-step hot-pressing.

Abstract: A mixed polymer liquid is prepared by mixing a polycarbosilane-dissolved organic solvent with poly(methylsilane) and moderated to viscosity of 5-20 Pa.s by heat-treatment to promote partial cross-linking reaction. The mixed-polymer is then melt-spun to fiber at 250-350° C. The fiber is cured by treatment at 100-200° C. in an oxidizing atmosphere, and baked at 1000° C. or higher. Due to thermosetting action of poly(methylsilane), the mixed polymer liquid is continuously melt-spun without breakage, and SiC fiber produced in this way is useful for reinforcement of SiC composite excellent in toughness, strength and heat-resistance.

Abstract: SiC fiber-reinforced SiC-matrix composite has the structure that SiC filaments are inserted into SiC matrix formed as a pyrolysis product of polyvinyl-silane (PVS) infiltrated into openings of said SiC filaments. PVS as a polymeric SiC precursor has structural units (a) and (b) at an a/b ratio of 1. A SiC fiber preform is impregnated with PVS slurry in an open or vacuum atmosphere, preheated at 300-400° C. in an inert gas atmosphere to moderate PVS to a viscous or semi-cured state, and then pyrolyzed in an argon atmosphere under application of a unidirectional pressure. A product is SiC fiber-reinforced SiC-matrix composite excellent in mechanical strength and high-temperature property with high density. The SiC composite is further densified by infiltration of PVS slurry suspending fine SiC particles therein or by repetition of impregnation with sole PVS and pressure-less pyrolysis after the pressurized pyrolysis.