Determination of Residual Surface Stresses Caused by Grinding in Polycrystalline Al2O3

Residual surface stresses introduced into polycrystalline Al₂O₃ during diamond grinding (320 grit) were examined by an X-ray direction technique commonly used for metals. Compressive stresses, estimated to be in the range 135 to 170 MPa and to extend 15 μm deep, were observed at the surface. It is believed that the compressive surface layer coincides with the plastic layer produced by the elastie/plastic interaction of the abrasive grains with the ceramic. The results are discussed with regard to the effect of the compressive layer on the extension of surface cracks.