Ceramic materials after sintering process are usually ground to improve the accuracy of dimension in finished components. Previous investigations reveal that strength properties are influenced by grinding conditions. It is noted that residual stresses as well as surface flaws, which are generated in grinding process of ceramics, may remarkably affect strength properties of ceramics. For successful applications of ceramics to engineering components, strength characteristics of notched components should also be elucidated because actual components have portions with stress concentration. Considering aspects as noted above, it is important to clarify effects of grinding conditions, including a notch-machining effect, on the strength in applications of ceramics. Since a strength scatter is very large in ceramics [ex. 9], a statistical approach is also required to investigate the influence of grinding conditions on the ceramic strength. In this work, the effect of grinding conditions, especially variations of the grit size of grinding wheel and the cutting depth, on a three-point bending strength was examined using smooth specimens of a pressureless sintered silicon nitride. In this case, the strength depending on distinct grinding conditions was discussed in the correlation with a grind-ing-induced residual stress. Form another aspect, four-point bending tests of a gas pressured silicon nitride and a pressure-less alumina were carried out using notched specimens with different notch shapes as well as smooth specimens of distinct sizes. The influence of notch machining on the bending strength was experimentally clarified.
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