APPLICATION OF DIAMOND COATING TO TOOL STEELS

Various attempts were made to grow diamond film on SKD 61 for tribological applications in the laboratory. One of the promising ways in which to achieve this end is to interpose an intermediate layer which is compatible with both diamond film and the substrate of SKD 61. Some refractory metals were found to be satisfactory for this particular purpose. Molybdenum, for instance, was first deposited on SKD 61 by an electron beam evaporator at ambient temperature. Such molybdenum-deposited SKD 61 was first dry etched in hydrogen plasma to remove possible oxides and contaminations. Then diamond film was allowed to grow at a temperature of ∼ 500°C without much disturbance of the mechanical strength of the tool. This combination of diamond/molybednum/SKD 61 provided two interfaces leading to satisfactory adhesion strengths and an overall mechanical integrity. Carbides were often observed at the interface, but no oxide was detected. Multilayers of Mo and Ni as well as a single layer of TiN on SKD 61 were also explored in this research and they were proved to be effective in retarding the mutual alloying effect between carbonaceous materials and ferrous alloys. © 1992.