A Study on Residual Stress Measurement for Fine Ceramics by Indentation Fracture Method

When mechanical components of ceramics are machined, some extent of residual stress is necessarily introduced in the products. In the reliability evaluation of the ceramic components, it is important to know the residual stress introduced in the fabrication process. A simple method to measure the residual stress based on the indentation fracture (IF method) was standardized by the Society of Materials Science, Japan, in 2001. In order to examine the applicability of the above standard method, stress measurements were carried out for some ceramics such as alumina, mullite and silicon nitride. In the experiments, a definite residual stress was introduced by applying the static load through a vice, after which the residual stress was measured by the IF method. In addition, the residual stress introduced in the machining process was measured by the IF method and X-ray diffraction method, and the respective results were compared to each other. Typical results in this study were summarized as follows; (1) load criterion to transit the crack types to median from Palmqvist was clarified, (2) experimental results of residual stress were in good agreement with the stress level artificially given in advance and (3) residual stress in the surface layer measured by the IF method well corresponded to the value obtained by the X-ray diffraction method.