表面形貌对滑动接触界面摩擦行为的影响

为了研究表面形貌对拉延形成的滑动接触界面摩擦行为的影响,设计了一种新型的摩擦试验装置.在油润滑条件下,针对具有单向沟槽、规则圆形凹坑和随机表面的铝合金试样,以不同滑动速度与接触压力进行一系列摩擦试验.利用非接触式三维轮廓仪测量出试验前后试样的三维表面形貌参数,并选取表面高度算术平均偏差Sa,表面支承指数Sbi,中心区空体体积Vvc和谷区空体体积Vvv来分析滑动接触界面表面形貌的变化规律.结果表明:规则圆形凹坑表面比单向沟槽表面和随机表面具有较低的摩擦系数;在相对低的接触压力下,3种表面的摩擦系数随着接触压力的增大而减小,但在高的接触压力下,3种表面的摩擦系数随着接触压力的增大而增大;在接触压力一定的情况下,3种表面的摩擦系数对滑动速度有显著依赖性;表面形貌、滑动速度和接触压力是影响滑动接触界面摩擦行为的重要因素.

Effect of Surface Topography on the Interface Tribological Behavior of Sliding Contact

In order to investigate the effect of surface topography on the tribological behavior in sliding contact interface formed during strip drawing, a new friction test device was built. The sample used was aluminum sheet with three kinds of textures, i.e. regular micro-cavity surfac, unidirectional groove surface and random surface. The lubricated friction tests were performed under high contact pressures at different sliding velocities. The three dimensional surface topography of samples before and after friction tests were measured with non-contact optical profilometer, and variations of surface topography of samples were analyzed by using 3D surface parameters of the 3D average surface roughness S_a, surface bearing index S_bi, void volume in centre zone V_vc and void volume in valley zone V_vv. Experimental results show that regular micro-cavity surface had lower friction coefficient than unidirectional groove surface and random surface. At a relatively low contact pressures, the friction coefficient of the three kinds of surfaces decreased with the increase of contact pressure, and at a relatively high contact pressures, the friction coefficient of the three kinds of surfaces increased with the increase of contact pressure. The friction coefficients of the three kinds of surface were significantly dependent on the sliding speed at a certain contact pressure. Surface topography, contact pressure and sliding speed were shown to be crucial factors to variations of tribological behavior in the interface during sliding.