抄録
The main objective of this study was to clarify the strength degradation and the strain behavior of engineering ceramics at high temperature during long-term range. For this purpose, a high temperature creep testing machine for ceramics was newly developed together with a displacement measuring device. To begin with, alignment of load transmission train of this testing machine was carefully checked and sufficient performance of this testing machine was confirmed. Then, experiments were carried out by using sintered silicon nitride and sintered silicon carbide at several temperature levels up to 1723K and during long-term up to 1000 hours. The results indicated that the creep rupture curves of both ceramics showed a straight line relationship on log-log diagram of applied stress vs. rupture time at respective temperature levels, and furthermore that the scatter of the rupture lives may be negligible when compared with that of cyclic fatigue strength of these ceramics. Discussion on the creep rupture life of sintered silicon nitride from the viewpoint of the creep strain behavior revealed that the Monkman-Grant's law governed the rupture time of this type of ceramics analogous to the case of metallic materials.
