系列磷酸酯水溶性离子液体在水中摩擦学行为研究

Tribological Performance of Serial Ammonium-Phosphate Ionic Liquids as Lubricant Additives in Water

基于分子设计的理念,将辛醇、十二醇、十八醇分别与五氧化二磷反应得到不同链长的磷酸酯,再与二乙醇胺反应制备出3种水溶性离子液体润滑添加剂。采用红外光谱分析定性确认添加剂的结构,并应用热重分析3种添加剂的热稳定性。通过四球摩擦磨损试验机评价3种添加剂在水体系中的摩擦学性能。采用扫描电子显微镜(SEM)和X射线光电子能谱(XPS)对磨损表面进行表征分析,探讨其摩擦化学机制。结果表明:3种添加剂的热分解温度较高,分别为130、165、178℃;3种添加剂均能显著提高水体系的减摩抗磨和耐极压性能,且其抗磨和耐极压性能随着链长的增加而增强,这可能与添加剂的吸附能力和反应活性有关,烷基链较长的添加剂更容易吸附在金属表面,高载荷下能更快地与金属发生反应形成边界润滑膜;添加剂在表面形成的反应膜主要由铁氧化物,磷酸铁构成;边界润滑膜的存在提高了水体系的摩擦学性能,丰富了水作为润滑介质的使用场合。

Based on the method of molecule design,Octanol,lauryl alcohol and octadecyl alcohol were reacted with phosphorus pentoxide respectively to obtain phosphate esters with different chain lengths.The products were neutralized with diethanol amine to prepare three kinds of Ammonium-Phosphate ionic liquid additives.The structures of the additives were confirmed by FI-IR,and the thermal stability was analyzed by thermogravimetric analysis.The tribological performance of three additives in water was evaluated by four-ball tester.The worn surface was investigated by scanning electron microscope(SEM) and X-ray photoelectron spectroscopy(XPS).The results show that three additives have good thermal stability with the initial decomposition temperature of 130,165,178 ℃.Three additives can significantly improve the tribological performance in water system,and the additive with longer alkyl chain length has better tribological performance,which can be attributed to the long chain’s outstanding adsorption capacity and chemical reactivity.The chemical reacted layer in worn surface is consisted of iron oxide and ironic phosphate.The tribological performance of water is largely enhanced by the layer of boundary film so that water as lubrication medium can be applied in various working conditions.