Volatility Diagrams for Silica, Silicon Nitride, and Silicon Carbide and Their Application to High‐Temperature Decomposition and Oxidation

Abstract

Volatility diagrams—isothermal plots showing the partial pressures of two gaseous species in equilibrium with the several condensed phases possible in a system—are discussed for the Si‐O and Si‐N systems, and extended to the Si‐N‐O and Si‐C‐O systems, in which the important ceramic constituents SiO 2 , Si 3 N 4 , Si 2 N 2 O, and SiC appear as stable phases. Their use in understanding the passiveactive oxidation transitions for Si, Si 3 N 4 , and SiC are demonstrated.