Abstract Tribological behavior of Cu is peculiar among soft metal when it rubs on diamond flat in experiments, and passivating element F and H at Cu/diamond interface can affect mechanical properties and even tribological characteristics as well, related special adhesive transfer (fracture location) and adhesion tuning mechanism at Cu/diamond interface remain obscure. Here, we investigate the interfacial structure change, electronic and mechanical properties of Cu/diamond and interface with fully F passivation (Cu/diamond:F) through first-principles calculations. The study shows that Cu(111)/diamond(111) interface exhibits the special phenomenon of adhesive transfer (different cleavage location and interfacial strength under applied load) due to adhesion, and this contribute to different frictional properties among soft metal. The effect on mechanical properties of F at Cu/diamond interface is studied systematically, passivation of fluorine on diamond surface reduces work of separation of the interface significantly, from 3.64 to 0.02 J/m2. Combining with kinetic analysis, we gain that fluorine might be a kind of promising adhesion-reducing element at interface and improve related tribological characteristics of Cu(111)/diamond(111) system. The results of this study benefit the understanding of different tribological properties of Cu/diamond system, adhesion reduction mechanism of fluorine at interface and its effect on tribological behavior at atomic scale.

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铜/金刚石界面的粘合剂转移和氟钝化的粘合减少机制：第一性原理研究

摘要 实验中Cu在金刚石平面上摩擦时，Cu在软金属中的摩擦学行为是特有的，Cu/金刚石界面钝化元素F和H会影响力学性能甚至摩擦学特性，相关的特殊粘合剂转移（断裂位置）和Cu/金刚石界面的粘附调节机制仍然不清楚。在这里，我们通过第一性原理计算研究了 Cu/金刚石的界面结构变化、电子和机械性能以及完全 F 钝化的界面（Cu/金刚石：F）。研究表明，Cu(111)/金刚石(111)界面由于粘附而表现出特殊的粘附转移现象（不同的解理位置和施加载荷下的界面强度），这有助于软金属之间不同的摩擦性能。系统研究了氟对Cu/金刚石界面力学性能的影响，金刚石表面氟的钝化显着降低了界面分离功，从3.64 J/m2 降低到0.02 J/m2。结合动力学分析，我们认为氟可能是一种很有前景的界面附着减少元素，并改善了Cu（111）/金刚石（111）体系的相关摩擦学特性。该研究结果有助于理解Cu/金刚石体系的不同摩擦学特性、氟在界面处的粘附减少机制及其对原子尺度摩擦学行为的影响。结合动力学分析，我们认为氟可能是一种很有前景的界面附着减少元素，并改善了Cu（111）/金刚石（111）体系的相关摩擦学特性。该研究结果有助于理解Cu/金刚石体系的不同摩擦学特性、氟在界面处的粘附减少机制及其对原子尺度摩擦学行为的影响。结合动力学分析，我们认为氟可能是一种很有前景的界面附着减少元素，并改善了Cu（111）/金刚石（111）体系的相关摩擦学特性。该研究结果有助于理解Cu/金刚石体系的不同摩擦学特性、氟在界面处的粘附减少机制及其对原子尺度摩擦学行为的影响。