Thermo-Chemical Wear Mechanism of Ultrafine Diamond Cutting Edge

Durability of cutting edge is a common requirement for ultra-precision cutting tool。Because the cutting edge under attritious contact with workmaterial is inevitably subject to elevated temperature，thermo-chemical process is considered to be essential mechanism on wear of diamond cutting tool.To understand the wear characteristics of cutting edge，the simplified experiments simulating the thermo-chemical process are carried out。On the other hand，based on the thermodynamics and quantum chemistry，the behavior of carbon atom on the surface of diamond specimen is analyzed in terms of binding energy。The results of the experiments and the analysis show that the mechanism of thermo-chemical wear process of diamond is as follows.The adsorption of oxygen atom on diamond surface deteriorate the stable structure or binding of carbon atom on the first layer of diamond crystal.The deterioration is enhanced when a specific metal atom exists near the adsorped oxygen atom due to the interaction between the metal and the oxygen atoms.When the temperature is elevated to the oxidization level of contacting metal，the carbon atoms on the specimen surface are removed as the form of carbon oxide。Therefore，the temperature and oxygen partial pressure of atmosphere are the important factors determining the thermo-chemical wear process of diamond.It is difficult to prevent the wear of cutting edge due to the restriction in realistic condition of atmosphere attainable。However，the application of thermo-chemical process to the high efficiency polishing of diamond can be feasible.

Durability of cutting edge is a common requirement for ultra-precision cutting tool. Because the cutting edge under attritious contact with workmaterial is inevitably subject to elevated temperature, thermo-chemical process is considered to be an essential mechanism on wear of diamond cutting tool. To understand the wear characteristics of cutting edge, the simplified experiments simulating the thermo-chemical process are carried out. On the other hand, based on the thermodynamics and quantum chemistry, the behavior of carbon atom on the surface of diamond specimen is analyzed in terms of binding energy. The results of the experiments and the analysis show that the mechanism of thermoーchemical wear process of diamond is as follows. The adsorption of oxygen atom on diamond surface deteriorate the stable structure or binding of carbon atom on the first layer of diamond crystal. The deterioration is enhanced when a specific metal atom exists near the adsorped oxygen atom due to the interaction between the metal and the oxygen atoms. When the temperature is elevated to the oxidization level of contacting metal, the carbon atoms on the specimen surface are removed as the form of carbon oxide. Therefore, the temperature and oxygen partial pressure of atmosphere are the important factors determining the thermo-chemical wear process of diamond. It is difficult to prevent the wear of cutting edge due to the restriction in realistic condition of atmosphere attainable. However, the application of thermo-chemical process to the high efficiency polishing of diamond can be feasible.