蛇纹石微粉对球墨铸铁摩擦副的减摩抗磨作用机理

采用MM-200摩擦磨损试验机评价了蛇纹石微粉作为润滑油添加剂对球墨铸铁的减摩抗磨作用.借助扫描电子显微镜、X射线能谱仪、纳米压痕仪、X射线光电子能谱仪等对磨损表面进行了分析,并探讨了其减摩抗磨机理.结果表明:蛇纹石微粉能显著提高球墨铸铁摩擦副的摩擦学性能.当添加量为0.5%(质量分数)时,能使摩擦系数较基础油降低51.5%,磨损量减少29.6%.磨损表面元素主要由Mg,Si,Fe,O,C组成,磨损表面光滑平整且具有较高的纳米力学性能.分析认为:由于蛇纹石微粉呈层片状结构,且表面存在大量的不饱和键而具有很高的化学活性,在摩擦力作用下趋向与摩擦表面发生物理、化学作用,形成铁镁的氧化物、水合氧化物、硅酸盐,铁的碳化物及石墨化碳等物相,可强化摩擦副表面,增强其自润滑能力,提高其减摩抗磨性能.

FRICTION REDUCTION AND ANTI-WEAR MECHANISM OF SERPENTINE MICRO POWDERS FOR SPHEROIDAL GRAPHITE IRON TRIBOPAIR

The friction reduction and anti-wear properties of serpentine micro powders as oil additives for spheroidal graphite iron tribopair were evaluated by means of a model MM-200 tribometer. The worn surface were analyzed by using scanning electron mi-croscope with energy dispersive analysis of X-ray apparatus, nano indenter and X-ray photoelectron spectroscopy (XPS). The friction reduction and anti-wear mechanism of the as-prepared powders were discussed accordingly. The results show that the friction coeffi-cient and the mass loss of the tribopair decreased by 51.5% and 29.6%, respectively, with additive concentration of 0.5% (in mass). The worn surface lubricated with additive-contained oil (mainly consisting of Mg, Si, Fe, O, C elements) exhibits rather smoother and higher nano mechanical properties compared to that with a base oil. XPS analysis of the worn surface indicates that the layer-structured serpentine micro powders, with a large number of unsaturated bonds, has higher chemical activity and tends to intro-duce the physicochemical effects on the worn surface under friction conditions. The production of some new phases (such as Fe or Mg oxides, hydroxides, silicates, Fe carbides and graphitized carbon), in the process can enhance the strength and self-lubricating capacity of the tribopair and favor the improvement of the friction reduction and anti-wear properties.