INVESTIGATION ON THE PROPERTIES OF CARBON-FIBER WITH C-SI FUNCTIONALLY GRADED COATING

In order to improve the interface properties of the metal matrix compo sites and their mechanical properties, the authors have investigated t he effectiveness of a chemically vapour deposited C-Si coating deposit ed on the surface of carbon fibre (CF); the influence of C-Si function al gradient coating on the properties of CF has also been studied. Exp erimental results show that the structure of carbon and silicon elemen ts is noncrystalline in the C-Si coating. This coating can greatly imp rove the oxidation resistance of CF, because functional gradient coati ng eliminates the mismatch factors between the coating and CF, restric ts the oxidation reaction rate, and renders the tensile strength of CF with functional gradient coating obviously higher than that of CF wit h Si, SiC and SiO2 single coating. When CF with functional gradient co ating was heat treated below 550 degrees C, the tensile strength of CF increased initially and then dropped. As the oxidation temperature wa s raised to 650 degrees C, the tensile strength of CF continuously dec reased with the progress of the heat treatment time.