Properties of Si3N4 ceramics sintered in air and nitrogen atmosphere furnaces

Mass loss and mechanical properties including density and morphology Of Si3N4 ceramics sintered in air and in N-2 atmospheres were comparatively studied. The trends of mass loss with increasing temperature of the Si3N4 sintered in air and in N2 atmospheres were significantly different. The densities of the specimens sintered at the same temperature both in air and in N-2 atmospheres were similar. However, the mechanical properties of the materials sintered in air were lower than those sintered in N-2 atmosphere. Vickers hardness (H-v), fracture toughness (K-IC) and biaxial flexure strength of the specimens sintered in air and in N-2 atmospheres were 12.7 GPa, 5.5 MPa.m(1/2) and 263 MPa, and 13.3-13.5 GPa, 6.0-6.8 MPa.m(1/2) and 340-406 MPa, respectively.