Fracture toughness of 3 mol% yttria-stabilized zirconia at cryogenic temperatures

Two basic aspects of fracture toughness for 3 mol% yttria-stabilized zirconia ceramics at cryogenic temperatures have been systematically investigated, including crack propagation resistance evaluation and fractographic assessments. By comparison with the obtained R-curve parameters, the calculated shielding stress intensity factors were significantly smaller than the measured ones from the R-curve at various temperatures, and the difference between calculated and measured terms could be minimized if the partial reversibility in the transformation and shear contributions were taken into account, or by assuming that there was some contribution to toughening from microcracking. In addition, the quantitative results of fracture mode were also presented showing a higher intergranular fraction at 77 K than at 293 K, which may be harmful to the fracture toughness.