Preparation and Properties of SiC Fiber with a Stable Excess Carbon Layer on the Surface

A new SiC fiber was prepared by the pyrolysis of polycarbosilane (PCS) fiber cured with unsaturated hydrocarbons. The fiber with oxygen content of 4wt%-6wt%, has high tensile strength of 2.5-2.8GPa. The specific resistance of the fiber is only about 0.5| ¤cm, which is much lower than general SiC fiber obtained from traditional air curing process. Results show that the fiber has an excess carbon layer with a thickness of about 50nm in the circular outer part, and the layer changes little after thermal exposure in argon. Compared with the ceramic grade fiber Nicalon NL202, thermal resistance to degradation of the fiber ˉs mechanical property is improved by 200-300 The low specific resistance of the fiber also exhibits excellent thermal stability, which almost remains at 0.4-0.8| ¤cm after thermal exposure test from the room temperature to 1600 n argon.