溅射沉积WS_x/Ni/a-C/Ni多层膜的微结构及大气环境摩擦学性能

Microstructure and Tribological Properties in Atmosphere of WS_x/Ni/a-C/Ni Multilayer Films Deposited by Sputtering

采用磁控溅射技术在硅基体上交替沉积WS2、Ni及非晶碳(a-C)层制备出不同Ni层厚度的WSx/Ni/a-C/Ni多层膜.利用扫描电子显微镜、X射线衍射仪、拉曼光谱仪、X射线光电子能谱仪等研究了多层膜的成分及微观结构;通过纳米压痕仪、划痕仪和球盘式摩擦磨损试验机等评价了薄膜的力学及大气环境中的摩擦学性能.结果表明:随着Ni层厚度的增加,WSx/Ni/a-C/Ni多层膜的致密度下降,ns/nw值(S与W原子百分数之比)由0.84降至0.73,WSx层以微晶或非晶的形式存在.多层膜的硬度和磨损率均随Ni层厚度的增加先降低后升高,但摩擦系数由0.22升至0.38,结合力先增大后减小. Ni层厚度为6 nm的多层膜的硬度可达13.4 GPa,抗氧化性能和耐磨性最优,磨损率仅为9.47×10–14 m3/(Nm).

WS_x/Ni/a-C/Ni multilayer films with different Ni layer thicknesses were successfully prepared by alternate depositing WS2, Ni and amorphous carbon(a-C) layer on silicon substrate with magnetron sputtering technique. The composition and microstructure of the films were investigated by using scanning electron microscopy, X-ray diffractometry, Raman spectroscopy and X-ray photoelectron spectroscopy. The mechanical and tribological properties of the films in air were evaluated by using nano-indentation tester, scratch tester and ball-on-disc tribotester. The results show that the density of WSx/Ni/a-C/Ni multilayer films decreased and the value of ns/nw(the atomic fraction ratio of S to W) dropped from 0.84 to 0.73 as increasing the Ni layer thickness, the WS2 layer was microcrystalline or amorphous.With the increase of Ni layer thickness, the hardness and wear rate of the multilayer film decreased first and then increased, but the friction coefficient increased from 0.22 to 0.38, the adhesion increased first and then decreased. The multilayer film with Ni layer thickness of 6 nm exhibited the hardness of 13.4 GPa, the excellent antioxidant properties and the best wear resistance,wear rate is 9.47×10–14 m3/(Nm).