Micro-thermal analysis of thermal conductance distribution in advanced silicon nitrides

Abstract

A micro-thermal analysis technique was applied to investigate advanced silicon nitride materials, which exhibit high thermal conductivity. Local thermal properties in the microstructure were evaluated, and the grain boundaries were observed to have lower thermal conductance than the Si3N4 grains. It was found that thermal conductance both in the grains and boundaries was lowered by the addition of the sintering aid Al2O3, which is soluble in Si3N4 grains. This indicates that high thermal conductivity in silicon nitride ceramics is achieved both by grain growth, leading to a reduction in boundary density, and by eliminating soluble elements in silicon nitride grains.