Study on Termo-Chemical Wear Mechanism of Diamond and Its Application to High Efficiency Polishing

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Thermo-chemical process is considered to be an essential mechanism of wear of diamond cutting edge in ultraprecision metal cutting, because the cutting edge under attritious contact with workmaterial is inevitably subject to elevated temperature. To understand the wear mechanism, the simplified experiments simulating the wear process of cutting edge are carried out. Analyzes on the behavior of chemical reaction between diamond and metal are also made based on the thermodynamics and first principal quantum calculation. The results of the experiments and analyzes show that the thermo-chemical wear by oxidation on the diamond surface contacting with a metal is predominant process when it is heated under the temperature that the metal can be oxidized and also the metal oxide can be deoxidized by diamond. The wear of diamond is also accelerated carbonization of the contacting metal or the diffusion of carbon atoms on diamond surface into the metal. Using the termodynamics analyzes, the conditions on temperature and oxygen partial pressure under which the diamond shows termo-chemical wear can be predicted. Based on the first principal calculation, the wear processes of diamond due to oxidation and carbonization can be well understood. The wear control of diamond tool seems to be difficult under the condition of realistic atmosphere attainable. However, the application of thermo-chemical process seems to be useful for the high efficiency polishing of diamond.