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°C under a controlled atmosphere. The nucleation and growth of β-SiC grains between 1400-1600°C are accompanied with nano pores formation and residual carbon generation. Above 1800°C, SiC fiber could be sintered to give a fully crystallized β-SiC with some α-SiC.