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SiC fiber reinforced SiC matrix (SiCf-SiC) composites with and without pyrolytic carbon interphase were prepared by polymer impregnation pyrolysis (PIP) progress. The effect of pyrolytic carbon interphase on the fracture behavior and mechanical properties of SiCf/SiC composites was studied. The results show that pyrolytic carbon interphase weakened the bonding between the matrix and the fibers. The mechanical properties of SiCf-SiC composites with carbon coating were improved effectively via fiber debonding and pulling-out from matrix under external loads. The flexural strength and fracture toughness of the above composites reached up to 498.52MPa and 24.09MPa•m 1/2, respectively.

Abstract. This paper investigated the Cf/SiC ceramic matrix composites. By utilizing different interfacial treatment processes to prepare carbon-fiber preform, the preform was then densified by infiltration and pyrolysis(PIP) with polycarbosilan/xylene solution as precursor, and the Cf/SiC ceramic matrix composite specimens were fabricated. Mechanical tests such as bending test and fracture toughness were performed for Cf/SiC samples. The results show that the interfacial bonding strength in the sample with high-temperature treatment process was improved due to removing surface sizing. The samples which were treated up to 1400℃ exhibited the highest three-point flexural strength, up to 595MPa; The samples which were treated up to 1400℃ and deposited by pyrolytic carbon(PyC) coating shows the highest fracture toughness value which was 20.70MPa•m1/2.