金刚石室温疲劳机理的试验研究

本文阐述了金刚石室温疲劳破坏现象的产生，简单介绍了研究金刚石室温疲劳的实验方法——软压头技术。分析了一般疲劳破坏的过程和机理，对金刚石室温疲劳破坏机理作了理论上的推导，提出了应力腐蚀使金刚石产生疲劳破坏的理论——应力集中提高表面原子活性引起应力腐蚀，在理论的基础上得到了金刚石疲劳速率公式。并采用软压头技术分别以PCD、CBN、Si3N4、Tib2等作为软压头材料，在自行研制的金刚石疲劳试验机上对不同氮含量的金刚石样品进行了疲劳实验，在实验数据的基础上绘制出了不同氮含量金刚石的疲劳曲线图，并对实验结果与疲劳破坏机理进行比较分析，得出结论：不同氮含量的金刚石，氮含量越高，金刚石疲劳破坏会越快出现，即疲劳强度越小，氮含量越低，裂纹扩展速度越慢，即疲劳强度越大。这从理论上和实验上论证了应力腐蚀引起金刚石室温疲劳的理沦。

Experimental Study of the Theory of the Diamond's Fatigue at Room Temperature

In this paper the theory of the fatigue of diamond at room temperature was studied and the soft impressor technique was introduced. The stress corrosion was considered to produce the fatigue crack of diamond. Impressors made of PCD, CBN, Si3 N4 and Tib2 were used in the fatigue experiment. The mechanism of fatigue of diamond was explored from the point view of crystal structure and mechanics. Experiment results showed that fatigue of diamond at room temperature exists and the stress corrosion may result in the fatigue of diamond at room temperature. Several fatigue curves of diamonds with different nitrogen contents were obtained through experiments. It was concluded that the fatigue intension of natural diamonds was bigger than synthetic diamonds. Moreover, to natural diamonds,the higher the nitrogen content, the lower the fatigue intension.