射频反应磁控溅射法制备的氟化类金刚石薄膜摩擦特性研究

以高纯石墨做靶,CHF3和Ar气为源气体,采用射频反应磁控溅射法在不同流量比条件下制备了氟化类金刚石(F-DLC)薄膜.利用原子力显微镜、纳米压痕仪、拉曼光谱和红外光谱、摩擦磨损测试仪对薄膜的表面形貌、硬度、键结构以及摩擦性能做了具体分析.表面形貌测试结果表明,制备的薄膜整体均匀致密,表现出了良好的减摩性能.当CHF3与Ar气流量比r为1:6时,所得薄膜的摩擦系数减小至0.42,而纳米压痕结果显示,此时薄膜的硬度也最高.拉曼和红外光谱显示,随着r的增加,薄膜中的F浓度呈上升趋势,薄膜中的芳香环比例减小.研究表明,F原子的键入方式是影响F-DLC薄膜摩擦系数的一个重要因素,CF2反对称伸缩振动强度的减弱和CC中适量碳氢氟键的形成都能导致薄膜具有相对较低的摩擦系数.

Frictional properties of fluorinated diamond-like carbon films prepared by radio frequency reactive magnetron sputtering

The fluorinated diamond-like carbon (F-DLC) films are prepared by radio frequency reactive magnetron sputtering with different flow ratios of CHF₃ and Ar as a source gas and pure graphite as a target. Surface morphology, hardness, bonding configuration and tribological properties are investigated by atomic force microscope, nanoindenter, Raman spectra, Fourier transform infrared (FTIR) spectra and a ball-on-disk test rig, respectively. The results show that the F-DLC films are distributed compactly and homogeneously and exhibit good friction-reducing behaviors. The minimum of friction coefficient reaches about 0.42 at r=1 ∶6 while the hardness of films is highest. Raman spectra and FTIR spectra reveal that with the increase of r, the fluorine content gradually increases. However, the intensity ratio I_D/I_G of Raman bands of disordered graphite (D-band) and graphite (G-band) of F-DLC films decreases, which is indicative of the decrease of the fraction of aromatic ring. The results also show that the F content is another significant factor which affects the friction coefficient. The weakening of —CF₂ asymmetric stretch vibration intensity and the formation of CFH in C C chains may result in a lower friction coefficient of F-DLC films.