アルミナセラミックスの表面性状と強度

概要

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Mechanical properties of ceramics are sensitive to the microstructure of the machined surface. The fracture strength has been studied in the past as a function of surface roughness of ceramics, and it has been noticed that micro cracks exist in the ground surface layers. The microcracks caused by grinding abrasion, however, have not been clearly observed. The purpose of this study was to describe th.e micro-structure of ground surface of alumina ceramics and to obtain its influence on the bending and fatigue strengths. The following results are obtained. (1) According to TEM observations, both the inter- and the trans-granular fracture occurred in the surface layers. (2) Micro cracks developed in the area of trans-granular fracture. (3) The structure image of the strained area suggested that lattice deformation occurred when diamond grains hit an alumina grain. Some dislocations were also observed in the alumina grain. (4) The diamond grain size of the grinding wheel did not have so much effect on the three point bending strength. (5) The specimen ground by a #325 diamond grinding wheel showed slightly higher fatigue strength than by a #800 diamond grinding wheel.
1992-07-15