DLC薄膜沉积对不同表面形貌的钛微弧氧化膜层摩擦学性能的影响

Influence of DLC Film Deposition on the Tribological Property of Micro-arc Oxidation Films with Different Surface Morphologies on Titanium

目的在钛微弧氧化(MAO)膜层表面沉积类金刚石碳(DLC)薄膜,探索DLC薄膜沉积对不同表面形貌微弧氧化膜层摩擦学性能的影响。方法在铝酸盐电解液体系中,通过改变微弧氧化时间(10、60min)制备表面粗糙度与平均孔径不同的两种微弧氧化膜层MAO_10和MAO_60,而后利用磁控溅射技术在其表面沉积DLC薄膜,获得MAO/DLC复合膜层。通过白光共聚焦显微镜、CSM球盘式摩擦磨损试验机、Mahr轮廓仪和扫描电子显微镜等实验设备,对膜层的表面粗糙度、微孔尺寸、摩擦系数、磨损率和磨痕形貌等进行观察和分析。结果微弧氧化时间增加导致MAO膜层的表面粗糙度增大,表面微孔数目下降但平均孔径增大。DLC沉积可以在MAO_10膜层表面形成较好的DLC覆盖层,但在粗糙度较高和孔径较大的MAO_60膜层表面呈现出明显的不连续分布。MAO/DLC复合膜层的粗糙度和平均孔径明显低于MAO膜层。摩擦学性能测试表明,MAO_10/DLC复合膜层的摩擦系数和磨损率相比于MAO_10膜层均明显下降,MAO_10膜层和MAO_10/DLC复合膜层的稳定摩擦系数分别为0.85和0.24,磨损率分别为12.76×10^-6mm^3/(N·m)和3.71×10^-6mm^3/(N·m);MAO_60/DLC复合膜层的摩擦系数和磨损率则与MAO_60膜层比较接近,MAO_60膜层和MAO_60/DLC复合膜层的稳定摩擦系数分别为0.77和0.67,磨损率分别为68.02×10^-6mm^3/(N·m)和61.81×10^-6mm^3/(N·m)。结论在表面较平整且平均孔径较小的钛微弧氧化膜层表面沉积DLC薄膜时,所得MAO/DLC复合膜层在摩擦过程中可以形成较为连续的润滑层,其摩擦学性能良好。相反,在表面粗糙和平均孔径较大的钛微弧氧化膜层表面沉积DLC薄膜时,所得MAO/DLC复合膜层在摩擦过程中难以形成连续的润滑层,其摩擦学性能较差。

The work aims to deposit diamond-like carbon (DLC) film on the surface of micro-arc oxidation films on titanium and explore the influence of DLC film deposition on the tribological property of micro-arc oxidation (MAO) films with different surface morphologies.Two kinds of MAO films (MAO_10 and MAO_60) with different surface roughness and micro- pore sizes were fabricated in the aluminate electrolytes with the MAO time of 10 min and 60 min,respectively.Then,a DLC film was deposited on the surface of the MAO film by magnetron sputtering to obtain MAO/DLC composite films.The surface roughness,micro-pore size,friction coefficient,wear rate and wear scar morphology of the MAO and MAO/DLC films were observed and studied by confocal microscope,CSM friction tester,Mahr surface profiler and scanning electron microscopy (SEM).The increasing MAO time increased surface roughness and average micro-pore size,but decreased micro-pore number of MAO films.After the DLC deposition,a relatively good DLC top layer was formed on the surface of MAO_10 film.However, the DLC top layer on the MAO_60 film exhibited a discontinuous distribution due to the high surface roughness and large micro-pore size of MAO_60 film.The surface roughness and average micro-pore size of MAO/DLC composite films were lower than that of MAO films.The tribological test results showed that the friction coefficient and wear rate of MAO_10/DLC composite film were significantly lower than that of MAO_10 film.The stable friction coefficient of MAO_10 film and MAO_10/DLC composite film was 0.85 and 0.24,and the wear rate was 12.76×10^-6 mm^3/(N·m) and 3.71×10^-6 mm^3/(N·m),respectively. In contrast,the stable friction coefficient and average wear rate of MAO_60/DLC composite film were near to that of MAO_60 film.The stable friction coefficient of MAO_60 film and MAO_60/DLC composite film was 0.77 and 0.67,and the wear rate was 68.02×10^-6 mm^3/(N·m) and 61.81×10^-6 mm^3/(N·m),respectively.When the DLC film is deposited on the MAO film with relatively smooth surface and small micro-pore size,the fabricated MAO/DLC composite film has good tribological property due to the formation of a continuous lubricating layer.In contrast,when the DLC film is deposited on the MAO film with rough surface and large micro-pore size,the continuous lubricating layer is difficult to form,thus leading to a relatively poor tribological property.