Abstract
Application of CVD diamond (CVDD) to cutting tools is well known, however, sufficient utility in practice has not been achieved yet. The biggest technical problem is delamination caused by strong impact in cutting work piece materials. On the other hand, diamond has many specific properties compared to other hard materials. When used under conditions where strong mechanical impact is induced, CVDD films are expected to show unique behaviors as compared to other conventional hardness films. In order to improve the adhesion of CVDD films, it is very important to reveal the damage processes of CVDD films caused by impact. In this paper, we described the knowledge of damage processes of CVDD films by cyclic impact via observations by a mechanically scanned acoustic microscope. Based on these investigations, we proposed a model for the damage of CVDD films. That is, the damage of CVDD films is triggered by the occurrence of cracks. Extension of cracks to the top surface and delamination around the cracks are gradually extended, and lastly CVDD films are peeled off along the cracks from the substrate.
