UHTC-carbon fibre composites: Preparation, oxyacetylene torch testing and characterisation

Current generation carbon-carbon (C-C) and carbon-silicon carbide (C-SiC) materials are limited to service temperatures below 1800°C and materials are sought that can withstand higher temperatures and ablative conditions for aerospace applications. One potential materials solution is carbon fibre-based composites with matrices composed of one or more ultra-high temperature ceramics (UHTCs); the latter are intended to protect the carbon fibres at high temperatures whilst the former provides increased toughness and thermal shock resistance to the system as a whole. Carbon fibre-UHTC powder composites have been prepared via a slurry impregnation and pyrolysis route. Five different UHTC compositions have been used for impregnation, viz. ZrB ₂, ZrB ₂-20vol% SiC, ZrB ₂-20vol% SiC-10vol% LaB ₆, HfB ₂ and HfC. Their high-temperature oxidation resistance has been studied using a purpose built oxyacetylene torch test facility at temperatures above 2500°C and the results are compared with that of a C-C benchmark composite.