Preparation and anti-oxidation properties of Si(O)C coated carbon-bonded carbon fibre composites

Abstract

A protective Si(O)C coating on the surface of the carbon fibres of carbon-bonded carbon fibre (CBCF) composites was fabricated using a sol–gel method using dimethoxydimethylsilane and methyltrimethoxysilane as precursors. The influence of preparation temperature on the pyrolysis behavior of siloxane gel, microstructure and oxidation resistance of Si(O)C coated CBCF composites are discussed. Results indicate that a uniform and dense SiOC glass coating with a thickness of 500–700 nm is obtained at 1200 °C and it has lower roughness parameters of 2.4 and 3.34 nm for mean roughness and root mean square roughness, respectively, accompanying a good interface bonding state with the carbon matrix. The SiOC glass coated CBCF composites exhibit superior oxidation resistance in the temperature range of 600 to 800 °C by encapsulating carbon, and their oxidation activation energy is 41.47% higher than those of the pristine ones.