Formation of carbon-rich layer on the surface of SiC fiber by sintering under vacuum for superior mechanical and thermal properties

SiC fibers have been intensively developed for application in advanced aerojet engines, stationary gas turbines and nuclear reactors of the future. In this work, SiC fibers with controllable carbon-rich layer were prepared by sintering under vacuum, which could be attributed to the release of gaseous silicon under vacuum at high temperature. The thickness of the carbon-rich layer on the fiber surface could be adjusted by changing the sintering temperature. Moreover, the carbon-rich layer was well distributed on the fiber surface, combining closely with the interior of the fiber. The as-prepared SiC fibers had high tensile strength and relatively low elastic modulus, which was favorable for weaving into different fabrics. Furthermore, the fibers also exhibited excellent ultra-high temperature resistance due to the presence of carbon-rich layer on the surface, which was better than that of the Hi-Nicalon and Hi-Nicalon S fibers.