类金刚石膜对CoCrMo合金摩擦性能的影响

目的研究类金刚石膜(DLC)在不同工况条件下的摩擦性能。方法使用磁控溅射技术,在CoCrMo合金表面沉积掺杂Cr元素的DLC薄膜。通过X射线衍射能谱和拉曼光谱对DLC膜表面的化学成分进行分析,采用扫描电镜(SEM)和原子力显微镜(AFM)观察DLC膜的表面形貌,借助摩擦试验仪测试DLC膜在不同工况条件下的摩擦性能。结果薄膜表面呈现颗粒状结构,且薄膜表面粗糙度在10 nm左右,物相分析表明,DLC薄膜为非晶化结构。在牛血清白蛋白(BSA)和NaCl溶液润滑条件下,DLC/CoCrMo摩擦副的平均摩擦系数(COF)分别趋于0.08,磨损区域存在少量的刮痕;而在干摩擦条件下,摩擦系数曲线表现出由高到低的变化趋势,平均摩擦系数约为0.21,同时在销磨损表面能观察到石墨化转移层。当接触压力为1 MPa时,平均摩擦系数约为0.10;接触压力增加至8 MPa时,平均摩擦系数约为0.08。结论润滑条件下,DLC膜表面悬键被钝化,减小其与配副表面之间的相互作用力,因此摩擦系数较低;干摩擦条件下,石墨化转移层充当固体润滑层,最终导致摩擦系数呈现下降趋势。DLC薄膜对摩擦配副具有明显的减摩效果。

Effect of Diamond-like Coating on Tribological Behaviour of CoCrMo Alloy

The aim of the paper was to investigate the tribological behavior of DLC coating under different working conditions. The DLC coating doped with Cr element was deposited on the CoCrMo alloy by magnetron sputtering. The chemical composition of DLC coating was analyzed by X-ray diffraction energy spectrum and Raman spectrum. The surface morphology of DLC coating was observed by scanning electron microscope (SEM) and atomic force microscope (AFM). The tribological properties of DLC coating under different working conditions were studied with a tribo-tester. Results showed that the surface of DLC coating presented granular structure and the roughness value was about 10 nm. Phase analysis showed that the DLC coating had amorphous structure. The average friction coefficient of DLC/CoCrMo tribo-pair was about 0.08 with the lubrication of BSA and NaCl solution respectively, and there were a few scratches on the wear area. Under the condition of dry friction, the curve of the friction coefficient showed a change trend from high to low, and the average friction coefficient was about 0.21. Meanwhile, the graphitization transfer layer could be seen on the worn surface of the pin. When the contact pressure was 1 MPa, the average COF was about 0.10. When the contact pressure increased to 8 MPa, the average COF was about 0.08. Conclusion stated that the suspended bond on the surface of DLC coating is passivated under the condition of lubrication, which reduces the interaction force between DLC coating and the mating surface. The COF is thus low. Under dry friction, the graphitization transfer layer acts as a solid lubrication layer which leads to the decrease of COF. DLC coating has an obvious antifriction effect on the friction pair.