Abstract:
Pressed specimens of α-Si3N4 (SN-E10) powder with Y2O3 and Al2O3 additives were successfully sintered without a serious mass loss at a temperature range of 1550-1700°C in an air atmosphere furnace using a set of specially designed, high purity A12O3 crucibles, Si3N4 packing powder and A12O3 filler. The agglomeration on sintering of both the packing powder and Al2O3 filler was encountered, but it could be optimized by using coarse size materials. Additionally, the deterioration of Al2O3 crucibles leading to cracking after several times of usage is still to be improved. On the contrary, Si3N4 ceramics could be sintered to full density (98%) reproducibly at 1700°C for 2 hours with an average biaxial bending strength of 420 MPa, Vickers hardness of 16 GPa and fracture toughness, K1C, of 5 MPam ½.
