Pressureless Sintering in the Si-Y-Mg-O-N System
The mechanical properties of pressureless sintered silicon nitride are often limited at temperatures above 1000°C due to the softening of the grain boundary phase which forms from the sintering additives necessary for liquid phase sintering. Improvements in the high temperature properties may therefore be possible by minimizing the amount of sintering additives needed for complete densification. However, to minimize the total amount of additives, a better understanding of the liquid phase properties and phase relations within the ceramic system is necessary. In this study, the densification behavior of pressureless sintered silicon nitride containing constant volume fractions of oxide sintering additives of varying composition was investigated. The densification behavior was analyzed in terms of the additive composition, the liquid phase properties, and the effects of phase relations within the ceramic system.
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