Thermal and mechanical properties of hot pressed translucent Y ₂O₃ doped Mg-α/β-Sialon ceramics

Different Sialon phases, intergranular phase and sinterbility of additives play an important role on thermal, mechanical and optical properties of Sialon ceramics. Hot pressed translucent Mg-α/β-Sialon composite was fabricated with MgO as a sintering additive. But with MgO, complete densification was not achieved because of its higher viscosity and higher melting point. Y₂O₃ is one of the best sintering additives to achieve complete densification and good mechanical properties in silicon nitride based ceramics. Therefore, different amount of Y₂O ₃ was added to Mg-α/β-Sialon composite and effect of Y₂O₃ addition on microstructure, thermal, mechanical and optical properties was investigated. α-Sialon phase was increased with increasing the amount of Y₂O₃ up to 1 wt.%, but addition of 2 wt.% Y₂O₃, most β-Sialon phase was observed. Thermal conductivity and coefficient of thermal expansion values were increased with increasing the amount of Y₂O₃. However, translucency was decreased in higher Y₂O₃ addition.