Abstract
Alpha type silicon nitride with Yb2O3 and MgO or MgSiN2 as sintering additives was sintered at 1900°C for 2-48h under 0.9MPa N2. The sintered bodies were evaluated density, weight loss, thermal conductivity and microstructure. Thermal conductivity of the sintered bodies increased with sintering time. The thermal conductivity of MgSiN2 doped Si3N4 was higher than that of MgO doped Si3N4. The thermal conductivity of Si3N4 was improved by about 20 W/mK by doping with MgSiN2 instead of MgO, and high thermal conductivity over 155 W/mK could be achieved in MgSiN2 doped specimen sintered for longer time (≈ 48 h).
