Mechanical and Thermal Properties of Silicon Nitride Hot Pressed with Adding Rare-earth Oxides

摘要

Mechanical and thermal properties of Si_3N_4 ceramics with various rare-earth oxides (La_2O_3, CeO_2, Lu_2O_3, Dy_2O_3, Sm_2O_3, Nd_2O_3, Yb_2O_3, and RuO_2) were investigated. Flexural strength of silicon nitride with addition of 5vol% Nd_2O_3, CeO_2, Dy_2O_3, and Sm_2O_3 showed higher value than that of silicon nitride with Lu_2O_3 and La_2O_3 added because they form denser microstructure and smaller elongated grain. Thermal conductivity of silicon nitride with an addition of 5vol% RuO_2 was more enhanced than that of silicon nitride added with Nd_2O_3, Sm_2O_3, and Dy_2O_3 because the addition of RuO_2 depressed grain growth. It is also associated with lattice oxygen governing thermal conductivity of Si_3N_4 when added rare-earth oxides.