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

热化学过程被认为是超精密金属切削中金刚石刃口磨损的重要机理，因为刃口与工件摩擦接触时不可避免地会受到温度升高的影响。为了解刃口磨损机理，进行了模拟刃口磨损过程的简化实验。基于热力学和第一主量子计算，分析了金刚石与金属之间的化学反应行为。实验和分析结果表明，在金属可氧化温度和金刚石可脱氧金属氧化物的温度下加热时，金刚石与金属接触表面主要发生氧化热化学磨损。金刚石的磨损也加速了接触金属的碳化或金刚石表面的碳原子向金属的扩散。通过热力学分析，可以预测金刚石发生热化学磨损的温度和氧分压条件。基于第一次主计算，可以很好地理解金刚石氧化和碳化的磨损过程。在现实环境条件下，金刚石刀具的磨损控制似乎比较困难。然而，热化学工艺的应用对于金刚石的高效抛光似乎是有用的。

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.