一种油溶性季铵盐离子液体作为PAO基础油添加剂的摩擦学研究

合成了新型季铵盐磷酸酯油溶性离子液体(N₈₈₈₁₆P₄)，采用热重分析仪(TGA)分析其热稳定性. 采用SRV-V微动摩擦磨损试验机和Bruker-NPFLEX表面非接触光学三维轮廓仪考察该离子液体作为聚α-烯烃(PAO 10)基础油减摩抗磨添加剂及其与商业添加剂二烷基二硫代磷酸锌(ZDDP)复配后的摩擦学性能. 结果表明:N₈₈₈₁₆P₄具有优异的油溶性能，与ZDDP具有良好的配伍性. 在室温和高温(100 ℃)条件下，N₈₈₈₁₆P₄均可显著改善PAO 10的减摩抗磨性能. 相较于与ZDDP复配，N₈₈₈₁₆P₄ 单独作为PAO 10添加剂表现出更优异的减摩抗磨性能. 铜片腐蚀试验结果表明，N₈₈₈₁₆P₄几乎没有腐蚀性，且与ZDDP复配后能够明显抑制ZDDP的腐蚀. 利用扫描电子显微镜(SEM)对磨斑表面形貌进行进一步分析，同时结合能谱仪(EDS)和X射线光电子能谱仪(XPS)对磨斑表面主要化学元素进行分析，证明N₈₈₈₁₆P₄能够与金属基底发生复杂的摩擦化学反应，由于其在摩擦副表面形成了含N和P元素的化学反应膜，从而起到优异的减摩抗磨作用. 

Tribological Properties of an Oil-soluble Quaternary Ammonium Salt Ionic Liquids as PAO Base Oil Additives

For machinery and equipment, rational use of lubricants can not only increase the service life of the machinery and the stability of mechanical operation, but also greatly improve fuel economy. In terms of industrial lubricant, it is mainly composed of base oil and additives. Among them, the base oil accounts for a relatively large proportion, and its nature determines the nature of the lubricant. The purpose of additives is to make up for some defects and deficiencies in the base oil in lubricating oils to achieve the effect of giving them special properties. For the improvement of lubrication under these two conditions, the most effective means is to use lubricating additives, which can form an effective protective film on the surface of the friction pair to prevent friction and wear caused by the direct contact of the friction pair. For this reason, oil-soluble anti-friction and anti-wear additives are usually added to lubricating oil to improve its anti-wear and anti-wear performance, so as to meet the lubrication requirements of machinery under different working conditions. Among different additives, anti-friction and anti-wear agents are of great significance to the anti-friction, anti-wear and load-bearing properties of lubricants. 　In this paper, a new type of oil-soluble quaternary ammonium phosphate ionic liquid (N₈₈₈₁₆P₄) was synthesized, and the thermal stability of each test sample was analyzed on a thermal gravimetric analyzer. The SRV-V fretting friction and wear tester and surface non-contact optical 3D profiler was used to investigate its tribological performance as anti-wear additive in base oil polyalphaolefin (PAO 10) and compounded with commercial additive zine dialkyldithiophosphate (ZDDP). Results showed that N₈₈₈₁₆P₄ had excellent oil solubility and good compatibility with ZDDP, no obvious stratification and precipitation were observed. The addition of N₈₈₈₁₆P₄ increased the initial thermal decomposition temperature of the PAO 10 composition, and with the increase of the amount of N₈₈₈₁₆P₄ added, the thermal decomposition temperature of PAO 10 increased to a certain extent. Under the conditions of room temperature and high temperature (100 ℃), PAO 10 had an obvious biting phenomenon. The addition of N₈₈₈₁₆P₄ with different mass fractions significantly improved the occurrence of this phenomenon. And with the increase of N₈₈₈₁₆P₄, the friction coefficient and wear volume of PAO 10 gradually decreased. The best tribological performance was obtained at the additive amount of 2%, i.e. the friction coefficient of 0.1 and the wear volume reduction of 80%. N₈₈₈₁₆P₄ significantly improved the anti-friction and anti-wear performance of PAO 10. Compared with its compounding with ZDDP, N₈₈₈₁₆P₄ as the additive of PAO 10 showed better anti-friction and anti-wear performance. The tribological performance was best at the additive amount of 1% because the friction coefficient dropped to about 0.1. The extreme pressure performance test showed that the addition of N₈₈₈₁₆P₄ reduced the amount of ZDDP without deteriorating the excellent load-bearing anti-friction performance. The copper corrosion test results showed that N₈₈₈₁₆P₄ was almost non-corrosive, and the combination of N₈₈₈₁₆P₄ and ZDDP significantly inhibited the corrosion of ZDDP. The surface morphology of the worn surface was analyzed by a scanning electron microscopy, energy spectrometer and X-ray photoelectron spectrometer were used to analyze the chemical state on the wear scars. It proved that N₈₈₈₁₆P₄ had complex tribochemical reactions with the metal substrate. The significant effects for ILs on the friction-reduction and anti-wear performances were attributed to the formation of tribofilm containing elements N and P on the worn surfaces.