Chen Zan, Du Naizhou, Li Xiaowei, Wei Xubing, Ding Jiaqing, Lu Shiqi, Du Shuangjiang, Feng Cunao, Chen Kai, Zhang Dekun, Lee Kwang-Ryeol
School of Materials Science and Physics, China University of Mining and Technology, Xuzhou 221116, China.
Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201, China.
Materials (Basel). 2023 Sep 7;16(18):6108. doi: 10.3390/ma16186108.
The textured design of amorphous carbon (a-C) film can significantly improve the tribological performance and service life of moving mechanical components. However, its friction dependence on different texture shapes, especially under different load conditions, remains unclear. In particular, due to the lack of information regarding the friction interface, the underlying friction mechanism has still not been unveiled. Therefore, the effects of contact pressure and textured shapes on the tribological behavior of a-C films under dry friction conditions were comparatively studied in this work by reactive molecular dynamics simulation. The results show that under low contact pressure, the tribological property of a-C film is sensitive to the textured shape, and the system with a circular textured surface exhibits a lower friction coefficient than that with a rectangular textured surface, which is attributed to the small fraction of unsaturated bonds. However, the increase of contact pressure results in the serious reconstruction and passivation of the friction interface. On the one hand, this induces a growth rate of friction force that is much smaller than that of the normal load, which is followed by a significant decrease in the friction coefficient with contact pressure. On the other hand, the destruction or even disappearance of the textured structure occurs, weakening the difference in the friction coefficient caused by different textured shapes of the a-C surface. These results reveal the friction mechanism of textured a-C film and provide a new way to functionalize the a-C as a protective film for applications in hard disks, MEMS, and NEMS.
非晶碳（a-C）薄膜的纹理设计能够显著提升移动机械部件的摩擦学性能及使用寿命。然而，其摩擦力对不同纹理形状的依赖性，尤其是在不同载荷条件下，仍不明确。特别是，由于缺乏关于摩擦界面的信息，其潜在的摩擦机制尚未被揭示。因此，本工作通过反应分子动力学模拟，对比研究了接触压力和纹理形状对干摩擦条件下a-C薄膜摩擦学行为的影响。结果表明，在低接触压力下，a-C薄膜的摩擦学性能对纹理形状敏感，具有圆形纹理表面的系统比具有矩形纹理表面的系统表现出更低的摩擦系数，这归因于不饱和键的比例较小。然而，接触压力的增加导致摩擦界面严重重构和钝化。一方面，这使得摩擦力的增长率远小于法向载荷的增长率，随后摩擦系数随接触压力显著降低。另一方面，纹理结构遭到破坏甚至消失，削弱了a-C表面不同纹理形状所导致的摩擦系数差异。这些结果揭示了纹理化a-C薄膜的摩擦机制，并为将a-C作为保护膜应用于硬盘、微机电系统（MEMS）和纳机电系统（NEMS）的功能化提供了新途径。
