npj: 润滑机理—无定形碳/α烯烃界面
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将无定形碳（a-C）膜与润滑油α-烯烃（C5H10）组合虽可显著改善移动机械部件的摩擦性能和寿命，但在较高的接触压力下，摩擦界面结构处的相关信息难以探测，因而难以知晓其摩擦机理。
来自韩国科学技术研究院的Xiaowei Li和Kwang-Ryeol Lee领导的团队，利用分子动力学模拟研究了接触压力下a-C / C5H10 / a-C滑动界面结构的演变。弄清了两种无定形碳膜与润滑剂烯烃油之间的摩擦机理。令人惊讶的是，两个表面在滑动期间，增加压力会导致摩擦减小达93%，接触压力继续增大，摩擦又会增加。这是因为压力进一步增加使得油分子分解，其中的碎片又重新与无定形碳表面结合，使它们间的润滑钝化。即，中等压力下由油流体动力所提供的润滑，好于高压下润滑，降低摩擦的效果更好。该研究揭示的压力和油在摩擦中的潜在作用机理，可以帮助指导改进润滑剂的设计，开发出新型长寿命有效润滑系统。
该文近期发表于npj Computational Materials 4: 53 (2018)，英文标题与摘要如下，点击左下角“阅读原文”可以自由获取论文PDF。
Mechanism of contact pressure-induced friction at the amorphous carbon/alpha olefin interface
Xiaowei Li, Aiying Wang & Kwang-Ryeol Lee
Combining an amorphous carbon (a-C) film with a lubricating oil can significantly improve the friction performance and lifetime of moving mechanical components. However, the friction mechanism is not well understood owing to a lack of information regarding the structure of the interface when exposed to high contact pressure. Here, we select linear alpha olefin, C5H10, as a lubricant and study the evolution of the structure of the a-C/C5H10/a-C sliding interface under contact pressure via reactive molecular dynamics simulation. Our results suggest that introducing C5H10 into the a-C/a-C interface reduces the friction coefficient by up to 93% compared with no lubricant, although the lubricating efficiency strongly depends on the contact pressure. In particular, increasing the contact pressure not only induces the binding of the lubricant with a-C, but also facilitates the dissociation of the C5H10 carbon-carbon skeleton by specific scissions, which governs the friction behavior. These results disclose the underlying lubrication mechanism and could enable the development of new and effective lubricating systems with long lifetimes.
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