Abstract This study investigates the influence of water lubrication on the friction of DLC films. It is found that water molecules at contact interfaces prevent the formation of interfacial C–C covalent bonds and show hydrodynamic lubrication effects, and thus effectively postpone the friction increase in initial friction stages. Moreover, for the small/medium amount of water molecules, they would diffuse into the DLC films during further sliding, hence highly decrease the interfacial density of carbon networks but inhibit their graphitization. This suggests that the degraded mechanical strengths of DLC films induced by the water diffusions at the interfaces contribute much to the friction reduction of these films, which improves the current understanding that such reduction is mainly caused by tribochemical reactions.

中文翻译：

---

水润滑下类金刚石碳膜的摩擦行为：分子动力学研究

摘要 本研究研究了水润滑对 DLC 薄膜摩擦的影响。发现接触界面处的水分子阻止了界面 C-C 共价键的形成并表现出流体动力润滑效应，从而有效地推迟了初始摩擦阶段的摩擦增加。此外，对于中小量的水分子，它们会在进一步滑动过程中扩散到 DLC 薄膜中，从而大大降低碳网络的界面密度，但会抑制其石墨化。这表明由界面处的水扩散引起的 DLC 膜的机械强度降低对这些膜的摩擦减少有很大贡献，这提高了目前对这种减少主要由摩擦化学反应引起的理解。