N/P无卤素离子液体润滑剂的链长与摩擦学性能的关系

合成了不同链长的N/P无卤素离子液体(NPILs:缩写为NP-11114，NP-11116，NP-11118)润滑剂，以聚α-烯烃(PAO 10)和卤素离子液体1-辛基3-甲基咪唑六氟磷酸盐(L-P 108)作为参照样，评价NPILs、PAO 10及L-P 108之间黏温性能、热稳定性以及室温和高温条件下的钢/钢摩擦副润滑剂的性能差异，探索了NPILs阳离子链长变化对其物理化学性质和摩擦学性能的影响规律. 结果表明:NPILs的黏度高于PAO 10和L-P 108，热分解温度低于PAO 10和L-P 108，NPILs黏度和热分解温度随着链长的增加而增加. 作为钢/钢摩擦副的润滑剂时，NPILs室温状态下减摩性能不及L-P108，但是NP-11118的抗磨性能优于L-P108；高温状态下，NPILs的减摩抗磨性能均优于L-P 108. 在常温和高温下NPILs相比PAO 10均具有优异的减摩抗磨性能，而且摩擦学性能随着烷基链长的增加而提高. 通过对磨斑表面进行扫描电镜分析证明这类离子液体具有优异的抗磨性能，通过EDS和XPS对磨斑表面的元素进行分析结果表明这类离子液体优异的摩擦学性能归因于离子液体结构中包含的N、P元素与金属基底发生摩擦化学反应所形成的具有优异减摩抗磨特性的摩擦化学反应膜. 

The Relationship Between the Chain Length and Tribological Properties of N/P Halogen-Free Ionic Liquid Lubricants

N/P halogen-free ionic liquids (NPILs: code as NP-11114, NP-11116, NP-11118) lubricants with different chain lengths were synthesized. The viscosity-temperature properties, thermal stability and lubricating properties of these ionic liquids were evaluated by using poly-α-olefin (PAO 10) and 1-octyl-3-methylimidazole hexafluorophosphate (L-P 108) as a reference. The effects of cation chain length changes of NPILs on their physicochemical properties and tribological properties were studied. The results show that the viscosity of NPILs is higher than PAO 10 and L-P 108, and the thermal decomposition temperature is lower than that of PAO 10 and L-P 108. The viscosity and thermal decomposition temperature of NPILs increase with the increasing chain length. As lubricants for steel/steel friction pairs, NPILs have lower friction reduction performance than L-P108 at room temperature, but the wear resistance of NP-11118 is better than L-P108; at high temperatures, the friction reduction and wear resistance of NPILs are better than L-P 108. NPILs have excellent antifriction and anti-wear properties both at normal temperature and high temperature, and tribological properties increase with increasing alkyl chain length. Scanning electron microscopy (SEM), elemental analysis and XPS results of the wear spot demonstrate that the excellent tribological properties of such ionic liquids are attributed to the tribochemical reaction of metal substrates and N, P in the ionic liquid structure to form tribo-film with excellent antifriction and antiwear properties.