表面织构钛合金的干摩擦和全氟聚醚油润滑下的摩擦学性能研究

Tribological Property of Titanium Alloy Surface with Different Texture Structure under Dry Friction and Perfluoropolyether Lubrication

利用激光加工技术在钛合金表面构造不同凹坑直径和密度的织构图案,采用UMT摩擦磨损试验机考察了不同织构形貌钛合金在干摩擦及全氟聚醚油润滑下的摩擦学性能,利用表面轮廓仪、扫描电镜(SEM)和X射线光电子能谱仪(XPS)对摩擦前后的表面形貌及磨痕成分进行观察分析.研究结果表明:干摩擦条件下,织构结构及其几何形貌显著影响凹坑容纳磨屑能力和表面接触应力,凹坑直径为200μm,织构密度为8.7%的钛合金表面减摩抗磨性能最好,与未织构相比其摩擦系数和磨损率分别降低了23.0%和39.7%,这主要由于凹坑可收集磨屑,减少第三体磨损;全氟聚醚油润滑条件下,表面织构影响流体润滑状态和摩擦表面金属氟化物生成,凹坑直径为200μm,织构密度为8.7%的表面具有更好的减摩抗磨效果,与未织构相比其摩擦系数和磨损率分别降低了17.4%和30.6%,这主要由于织构表面摩擦过程生成更多FeF_2,起到减摩抗磨作用.

Texture structures with varying dimple diameters and densities were produced on titanium alloy surface by laser processing technique.The friction and wear behaviors of the resulting titanium alloy with different texture structures were evaluated by UMT friction and wear tester,and the morphologies of the worn surfaces were characterized by surface profilometer and scanning electron microscopy.The chemical states of typical elements on worn surfaces were examined by means of X -ray photoelectron spectroscopy.The results show that the texture structure and morphology remarkably affected the capacity of holding wear debris and surface contact stress of the asprepared surface under dry friction.The modified titanium alloy surface with texture morphology of 200μm dimple diameter and 8.7% dimple density exhibited the best anti-wear and friction-reducing ability among all modified samples. Its friction coefficient and wear rate were reduced by 23.0% and 39.7%,respectively,as compared to the untreated titanium alloy surface,which was mainly due to the accumulation of debris in the dimples and thus reducing wear caused by third-body.As lubricated by PFPE,the surface texture affected the lubrication state and the metal fluoride was formed on the friction surface during rubbing process.The sample with texture morphology of 200μm dimple diameter and 8.7%dimple density also revealed better friction-reducing and anti-wear properties than the untextured one.Its friction coefficient and wear rate were reduced by 17.4% and 30.6%respectively,which mainly resulted from higher amount of FeF2 produced on textured surface that can reduce friction and wear during the rubbing process.