Clean surface reactions between diamond and steel

Abstract

THE rate of wear of diamond grinding on machining steel is known to be extremely high. For example, the wear rate of a diamond turning mild steel is 10⁴ times greater than when turning brass of comparable hardness¹. Several discussions of this wear conclude that it is due principally to the high local flash temperatures generated during machining and to the catalytic properties of the steel. Static experiments show that diamond graphitises at temperatures above 1,800K in vacuo, or above 1,100K in the presence of iron, and other experiments that flash temperatures of this order may be generated by machining. Hence, there is now general agreement that the wear proceeds by the graphitisation of the diamond; the surface layer of graphite being continually removed either by the abrasion of the steel or by solution in the steel^2–7. However, little information is available on the actual conditions prevailing at the interface during machining. Therefore, we have studied the mechanism of wear more closely by making quantitative measurements of the wear rates of round-nosed diamond tools turning billets of mild steel under well defined conditions.