Characterization of Chemical Wear of Boron-Doped Polycrystalline Diamond Films

Because diamond has high hardness and excellent wear resistance, it has been applied as a surface protective coating material for nonferrous metals and ceramics in a wide scope of mechanical tools. Particularly it is used for cutting tools for carbon fiber reinforced plastics: an excellent material for structural parts of aircrafts and automobiles. However, the resulting cutting tool performance is insufficiently high. Improvement is necessary. Earlier reports have described that the addition of boron to diamond films improves their mechanical properties such as wear resistance and fatigue strength. The origin of the wear property is complicated because the property comprises abrasive wear and chemical wear attributable to reaction with work materials. Numerous reports have described abrasive wear of diamond, but very few reports have described investigations of chemical wear for tools. For this study, we investigated the heat resistance and chemical wear characteristics of boron-doped diamond films synthesized using the hot filament CVD method. Results of these tests clarified that the addition of boron to the diamond film improves oxidation resistance and chemical wear characteristics remarkably.