Volatilization Associated with the Sintering of Polyphase Si 3 N 4 Materials

Weight loss which occurs while sintering composited Si 3 N 4 powders requires the loss of one or more of the end‐member constituents through a volatilization reaction. By plotting the direction of the compositional change on the appropriate equivalence phase diagram, the principal volatilization reaction can be determined. For a particular composition in the system Si‐Y‐N‐O sintered at 1750°C, the principal volatilization reaction was Si 3 N 4 (s) +3SiO 2 (s)→6SiO(g) +2N 2 (g).