Characterization of thermal conductivity of SiO2–Al2O3–Y2O3 glasses

•SiO2–Al2O3–Y2O3 glasses for sintering additive in ceramics.•The glasses shows increase in thermal conductivity at high temperature.•Glass system of SiO2–Al2O3–Y2O3 could be improved with the overall thermal conductivity of ceramics at high temperature.

The thermal properties of SiO2–Al2O3–Y2O3 glasses were investigated within a temperature range of 25–800 °C. This found that glass with a composition of 24Y2O3·21Al2O3·55SiO2 exhibits a thermal conductivity of 1.04 W/m K at room temperature, and thermal conductivity increases with temperature due to an increase in the amount of bridging oxygen. The thermal conductivity of glasses with a composition of xY2O3·21Al2O3·(79-x)SiO2, on the other hand, decreased with an increase in either the Y2O3 content or Al2O3/SiO2 ratio. This decrease in thermal conductivity was analyzed with respect to the decrease in phonon mean free path resulting from the increased non-bridging oxygen content, which revealed 24Y2O3·21Al2O3·55SiO2 to have the maximum thermal conductivity of 1.7 W/m K at 800 °C. Glass systems incorporating yttria can therefore be considered suitable sintering additives for highly thermally conducting ceramics such as silicon nitride.