Decorated pore detecting fatigue fracture origin of sintered Al_2O_3

摘要

Information on fracture origins is necessary to clarify the fracture mechanism of ceramics and their reliability as structural materials. The fatigue fracture of ceramics is believed to stem from the subcritical crack growth behaviour from the fracture origin. The fracture origin seemed to be a pore for sintered Al20_i plain specimens used in previous studies [1-3], but it is not easy to confirm this. Since these materials did not have clear mirrors, it was not easy to detect the fracture origin or crack initiation region clearly. In the process of the microscopic observations on the fatigue fractured surfaces of these materials, it was found that a pore had a string-like decoration. The decorated pore looks like a tadpole. The string-like decoration, referred to as the "tail", has not been studied before. Therefore, the tail characteristic was examined observing the fatigue fractured surfaces [3] of sintered AI20, plain specimens under rotary bending and static fatigue, and it is pointed out that the decorated pore is a useful sign for clarifying the fracture features of ceramics.