离子液体作为钢-聚四氟乙烯润滑剂的摩擦学性能研究

Tribological Performance of Ionic Liquids as Lubricants for Steel/PTFE contact

采用微动摩擦磨损试验机考察了不同条件下三种离子液体作为钢/聚四氟乙烯润滑剂的摩擦学性能,并与传统润滑油聚α-烯烃(PAO)及干摩擦条件下的摩擦学性能做了对比.采用扫描电子显微镜(SEM)及X射线光电子能谱仪(XPS)对磨斑表面进行了分析.结果表明:在变载变频试验条件下,三种离子液体与PAO的减摩抗磨性能相当;而在长磨试验条件下,离子液体均表现出优于PAO的摩擦学性能.原因是离子液体分子中的N、P、O等活性元素在摩擦过程中与聚四氟乙烯基底发生了摩擦化学反应,形成了具有润滑作用的化合物边界润滑膜,有效抑制了摩擦副的直接接触,而且该润滑膜的性能优于PAO润滑下形成的保护膜,从而使离子液体表现出优于PAO的摩擦学性能.

The tribological performance of steel/PTFE contact lubricated by ionic liquids（BA-DBP, BMIM-DBP, LP104） was evaluated on an Optimal SRV-IV oscillating friction and wear tester. In addition, the conventional lubricant poly α-olefin（PAO） was selected as reference lubricant. Meanwhile, the dry friction tests were carried out under the same test condition. The worn surfaces of the PTFE lubricated by different ionic liquids were analyzed by a JSM-5600 LV scanning electron microscope and a PHI-5702 multifunctional X-ray photoelectron spectrometer. As a result,the tribological properties of three ionic liquids were similar to that of PAO under the variable load and frequency condition. Nevertheless, the ionic liquids performed better lubricating behavior than conventional lubricant PAO under constant load and frequence test condition. The reason was that the tribochemical reactions between the PTFE substrates occurred and active elements of N, P and O in the lubricant molecule during the friciton tests and the compound boundary lubricating film on the friction surfaces effectively restrained the direct contact of the friction pair. Moreover,the lubricating property of the compound film was superior to that formed by the PAO.