Abstract
The room temperature transverse-rupture strength of Si3N4-10 mol%MgO-5.5 mol%A1203 ceramics was investigated in relation to the heating rate (0.07-0.33 Ks-1) during sintering, considering the effects of impurity carbon (about 1, 4 mol%) in Si3N4 powder and additional SiO2 (0-3 mol%).
It was found that the strength dependency on heating rate was largely affected by the carbon content in Si3N4 powder; the strength considerably decreased with decreasing heating rate in the case of Si3N4 powder with 4 mol% carbon, but it hardly changed with heating rate in the case of Si3N4 powder with 1 mol% carbon. The result was discussed on the basis of weight loss of specimens during sintering, carbon content of sintered specimens, microstructural defect which acted as a fracture source, etc.
