窒化ケイ素の高温繰返し荷重下での損傷評価

抄録

High temperature deformation behavior under cyclic loading are investigated in air for Si₃N₄ ceramics at 1673 K. Deformation recovery is observed and it is due to the viscosity of grain boundary phase in ceramics. As the loading cycles increase, the cumulative permanent deformation also increases. However, the total amount of permanent deformation lessens in the case of relatively long holdig time under no stress in the wave pattern. It seems that the cumulative plastic strain is the effective measurement values both to evaluate the damage states and to predict the fracture life time in Si₃N₄ ceramics at high temperature.