Chraracteristics of crack growth of alumina ceramics under cyclic loads

Abstract

Characteristics of crack growth under cyclic loading for alumina ceramics have been investigated. Three alumina ceramics with different grain size were fabricated by hot-pressing. Cyclic fatigue tests were carried out using four-point bend specimen. From examination of crack path and microstructural behavior from the tested specimens, grain bridging along the crack interface and intergranular fracture mode at the fracture surface were observed. The crack growth rate curve presented by using the cyclic parameter, DeltaK(eff)(*)/(1-K-max/K-IC), could be divided into three regions. These-regions were closely related to the fraction of intergranular fracture area. Crack,closure influencing the cyclic parameter was evaluated as a function of stress ratio.