Dense Polycrystalline SiC Fiber Derived from Aluminum-doped Polycarbosilane by One-Pot Synthesis

Polyaluminocarbosilane was synthesized by direct reaction of polydimethylsilane with aluminum(Ⅲ)-acetylacetonate in the presence of zeolite catalyst. A fraction of higher molecular weight polycarbosilane was formed due to the binding of aluminium acetylacetonate radicals with the polycarbosilane backbone. Small amount of Si-O-Si bond was observed in the as-prepared polyaluminocarbosilane as the result. Polyaluminocarbosilane fiber was obtained through a melt spinning and was pyrolyzed and sintered into SiC fiber from 1200~2000℃ under a controlled atmosphere. The nucleation and growth of β-SiC grains between 1400 - 1600℃ are accompanied with nano pores formation and residual carbon generation. Above 1800℃, SiC fiber could be sintered to give a fully crystallized β-SiC with some α-SiC.