Estimated and Evaluated Residual Stress by Vickers Indentation in Several Structural Ceramics

Residual stress was generated in several structural ceramics by sintering and grinding, then estimated using the Vickers indentation method. First, we sought the most appropriate pretreatment for measuring fracture toughness (basis value, KC), while preventing any influence from residual stress. This is important in estimating residual stress using the Vickers indentation method. Based on that value, the residual stress in Al2O3 and Si3N4 ceramics was estimated by the Vickers indentation method. Next, several problems in using the indentation method on ZrO2 ceramics were discussed, focusing on phase transformation. Residual stress in Al2O3 and Si3N4 was nearly eliminated by annealing the specimen after hand grinding. Consequently, this treatment method is considered effective for determining the basis value KC. The estimated residual stress value in Al2O3 and Si3N4 obtained by the Vickers indentation method at 98N corresponded closely to the values obtained by the X-ray method. The value for ZrO2, however, was larger than that found by the X-ray method. This difference is assumed to derive from phase transformation.