Thermal and Mechanical Properties of Magnesium Silicon Nitride Ceramics with Silicon Nitride Addition

Abstract

MgSiN₂ powder compacts with 1, 4, and 9 mol% of Si₃N₄ addition (sintering aid; 1 mol% of ytterbium oxide (Yb₂O₃) were hot-pressed at a temperature between 1550°C and 1750°C for 90 min. The relative density of MgSiN₂ compact with 4 mol% of Si₃N₄ addition hot-pressed at 1600°C for 90 min showed a maximum (94.1%) among the investigated samples. The fracture toughness value of MgSiN₂ specimen with 9 mol% of Si₃N₄ addition hot-pressed at 1600°C for 90 min was as high as 6.6 MPa·m^1/2, whereas the thermal conductivity of the MgSiN₂ specimen with 9 mol% of Si₃N₄ addition increased to 34.1 W·m^-1·K^-1 with increasing hot-pressing temperature of to 1750°C.