Investigation on the properties of carbon fibre with C-Si functionally graded coating

In order to improve the interface properties of the metal matrix composites and their mechanical properties, the authors have investigated the effectiveness of a chemically vapour deposited C-Si coating deposited on the surface of carbon fibre (CF); the influence of C-Si functional gradient coating on the properties of CF has also been studied. Experimental results show that the structure of carbon and silicon elements is noncrystalline in the C-Si coating. This coating can greatly improve the oxidation resistance of CF, because functional gradient coating eliminates the mismatch factors between the coating and CF, restricts the oxidation reaction rate, and renders the tensile strength of CF with functional gradient coating obviously higher than that of CF with Si, SiC and SiO2 single coating. When CF with functional gradient coating was heat treated below 550 degrees C, the tensile strength of CF increased initially and then dropped. As the oxidation temperature was raised to 650 degrees C, the tensile strength of CF continuously decreased with the progress of the heat treatment time.