Abstract: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 AmmoniumPhosphate 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 fourball 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.