Fabrication of SiC Ultrafine Fiber with Low Oxygen Content by Electrospinning, Thermal Curing and Pyrolysis of Cyano-Polycarbosilane

The thermal stability of the SiC ultrafine fibers is affected due to the large amounts of oxygen introduced during the oxidative curing process. In this work, cyano-polycarbosilane (PCSCN) and cyano-polyaluminocarbosilane (PACSCN) are synthesized by hydrosilylation reaction between PCS and acrylonitrile using a common radical initiator 2,2-azodiisobutyronitrile (AIBN). The results show that the main hydrosilylation reaction is α-addition, although some side-reactions of AN polymerization also occur. The PCSCN and PACSCN ultrafine fibers are obtained by electrospinning and can be cured directly by thermal treatment without oxidative curing in an inert atmosphere, due to the crosslinking reactions occurring between Si-H bonds and -C≡N groups. By thermal pyrolysis of the cured ultrafine fibers at 1200 ℃, the SiC ultrafine fibers with smooth and dense structure are obtained with oxygen contents as low as 3.10 wt