High temperature resistant SiC fibres derived from novel boron containing polycarbosilane

Abstract

Continuous SiC fibres have been widely studied and employed as important reinforcement of ceramic matrix composites. The heat resistant property of SiC fibres can be improved by introducing boron into the polycarbosilane (PCS) precursor. The boron containing PCS (B-PCS) was produced by reaction of low molecular PCS (L-PCS) with borane derivations. The molecular weight and ceramic yield of the B-PCS were characterised. By melt spinning of B-PCS, continuous green fibres were obtained. After curing and pyrolysis at 1200°C, the tensile strength of resulted filaments was measured up to 1·6 GPa. The tensile strength was decreased to 1·0 GPa after 1 h treatment at 1600°C under Ar atmosphere. When annealed at 1800°C, the surface was smooth without any significant defects and the tensile strength was 1·2 GPa. This paper introduces a novel high temperature resistant SiC fibre, and its properties of the B-PCS were described.

Keywords:

• Boron modified
• SiC fibre
• Polymer derived ceramics
• Heat resistant