SiC-based ceramic fibres: thermal stability and oxidation behaviour

摘要

The thermal stability of three commercial SiC-based fibres (Tyranno Lox M and Lox E, Hi-Nicalon) has been studied through their gaseous release and density changes followed by mass spectrometry and thermal expansion experiments. An axial shrinkage of aobut 0.8 percent has been measured in neutral and oxidizing atmosphere. at temperatures corresponding to the final pyrolysis treatment during the fibre processing (1200 deg C for Lox M and Lox E. 1400 deg C for Hi-Nicalon). This shrinkage is concommited with residual hydrogen removal for Tyranno fibres. In oxidizing conditions. the release of hydrogen results in water vapour formation which enhances the oxidation kinetics.