Improving frictional properties of DLC films by surface energy manipulation

Jia Wang; Kan Zhang; Fuguo Wang; Weitao Zheng

doi:10.1039/c8ra00580j

Improving frictional properties of DLC films by surface energy manipulation

RSC Adv. 2018 Mar 23;8(21):11388-11394. doi: 10.1039/c8ra00580j. eCollection 2018 Mar 21.

Authors

Jia Wang¹, Kan Zhang¹, Fuguo Wang², Weitao Zheng¹

Affiliations

¹ State Key Laboratory of Superhard Materials, Department of Materials Science, Key Laboratory of Automobile Materials, MOE, Jilin University Changchun 130012 P. R. China WTZheng@jlu.edu.cn.
² State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences Lanzhou 730000 P. R. China fgwang@licp.cas.cn.

Abstract

Surface energy is essential to the friction properties of materials, but until now the investigating scope for DLC films has still been narrow. In this paper, we try to expand the surface energy scope of DLC films to their limits by surface modification and study their influence on friction properties. In this case, we not only control the surface energy of DLC films but also manipulate that of the counter balls, by using piranha etching and octadecyltrichlorosilane (OTS) modification. The surface compositions, wettabilities and friction properties of DLC films and counter balls were investigated. The results indicate that the surface energies of DLC films and counter balls can be adjusted successfully in the ranges of 31.2 to 73.73 mJ m^-2 and 15.69 to 72.93 mJ m^-2, respectively. The frictional tests show that all the as-modified DLC films retain relatively stable friction curves, which derive from their good load-carrying and wear-resistance capabilities. Specifically, the DLC-OH covered with vast oxygen-containing groups shows poor frictional properties, owing to its high surface energy and strong adhesion. In contrast, the DLC-OTS exhibits amazing friction reduction properties, due to its ultra-low surface energy and special film structure.