功能化离子液体作为菜籽油添加剂的摩擦学研究

Tribological Properties of Functionalized Ionic Liquid as an Additive in Rapeseed Oil

合成了一种含酯基的功能化离子液体1-乙酸乙酯基-3-丁基咪唑双三氟甲磺酰亚胺盐(LF1-4),以传统添加剂丁辛基二硫代磷酸盐(T202)为对比,采用四球摩擦磨损试验机考察了其作为菜籽油(RO)添加剂的摩擦学性能;采用扫描电子显微镜(SEM)和X射线光电子能谱(XPS)仪分别对钢球磨斑表面的形貌和主要元素进行了观察和分析。结果表明,LF1-4作为RO的添加剂具有良好的减摩作用和显著的抗磨作用,在添加量(质量分数)为1.0%时达到最佳效果,能使磨斑直径减小38%;同时,LF1-4能有效提高RO的承载能力(PB),但其在RO中的减摩抗磨作用较T202稍差,推测是由于LF1-4在RO中的油溶性稍差所致。在高载荷下,离子液体LF1-4发生分解释放出活性元素氟等,与摩擦副表面的金属发生摩擦化学反应形成了铁的氟化物等新的化合物,从而减少了摩擦和磨损。

A functionalized ionic liquid containing ester-group, 1-ethoxycarbonylmethyl-3-methylimidazolium bis（trifluoromethylsulfonyl）imide （LF1-4）, was synthesized and its tribological properties as an additive in rapeseed oil （RO） were evaluated on a four-ball machine and compared with a traditional additive zinc butyloctyl-dithiophosphate （T202）. The morphology and main element of the worn scar surface of steel ball were analyzed by SEM and XPS, respectively. The results showed that LF1-4 possessed good friction-reducing ability and prominent anti-wear ability as an additive in RO. The optimum addition amount of LF1-4 in RO was 1.0%, when the wear scar diameter could be decreased by 38%. Furthermore, LF1-4 was effective in improving the load-carrying capacity （PB） of RO. But the friction-reducing and anti-wear ability of LF1-4 was slightly worse than that of T202 in RO, presumably due to the worse solubility of LF1-4 in RO. At high loads, some tribochemical reactions would take place between the active elements, such as fluorine released from the ionic liquid additive LF1-4 and fresh metal surfaces of rubbing pairs, to form ferric fluoride and some other new compounds, resulting in lower friction coefficient and good wear resistance.