Measurement and evaluation of the tensile strength of CVD SiC fibers with carbon coating

Tensile strength of SiC fibers uncoated and coated carbon by Chemical Vapour Deposition (CVD) method was tested at room temperature. Weibull distribution function is found to describe the distribution of the fibers' tensile strength excellently. The results show that the Weibull modulus and the average value of tensile strength about the SiC fibers coated carbon were both higher obviously than that of the SiC uncoated carbon. With the increase of gauge length and stain velocity, the average value of SiC fibers' tensile strength decrease and the Weibull modulus keep constant. Moreover, through analyzing the fracture of SiC fibers, it is found that a brittle fracture of the fibers can be seen clearly and the method of carbon coating can decrease the surface's defect, so the tensile strength of SiC fibers can be increased effectively.