Evaluation of surface and sub-surface cracks of ground ceramic

The grinding of ceramics using diamond grindings wheels initiates a system of surface and sub-surface cracks on the ground specimens. These surface and sub-surface cracks were investigated in this research. While surface cracks are visible and can be monitored easily with any of several techniques, sub-surface cracks are difficult to detect. This research investigates both types of cracks, using acoustic emission, three-dimensional topography and scanning electron microscopy. The research links the existence of surface and sub-surface cracks to different parameters such as the grinding wheel grit size, the wheel bond hardness, the depth of cut, the machine speed and the table feed. These conditions are believed to be responsible not only for the creation of these cracks, but also for the subsequent behavior of the cracks, i.e. the amount of damage that they can create. It seems from this investigation that control over these cracks is possible by adjusting the above-mentioned parameters. (C) 1999 Elsevier Science S.A. All rights reserved.