The Corrosion Behaviour of HIP Si3N4 and SiC/SiC Composite in Simulated Combustion Environments
The corrosion behaviour of a HIPed Si3N4 and a SiC/SiC composite has been studied in simulated combustion environments. It has been found that for both materials the oxidation behaviour and the gaseous corrosion behaviour are quite similar, but the corrosion kinetics is very sensitive to the sodium content in the environment. It is proposed that an increase of salt content in the corrosive environment may change the diffusion controlled corrosion process into areaction controlled process as a result of the formation of low viscosity silicate glass. The effects of salt (Na2SO2 or NaC1) on the devitrification of the amorphous silica are discussed.
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