几种含铅有机化合物作为润滑油添加剂的摩擦学特性及作用机理研究

在 2 0 0 SN矿物基础油中 ,用原位合成法、复分解法以及微波辅助合成法分别合成了月桂酸铅、油酸铅、环烷酸铅、硬脂酸铅和烷基水杨酸铅 .用四球摩擦磨损试验机 ,在高速低负荷及低速高负荷两组试验条件下评价了其摩擦学性能 .结果表明 :不同结构羧酸铅的油溶性、抗磨减摩性能以及抗极压性能存在较大差异 ,其摩擦学性能与羧基结构密切相关 ,环烷酸铅和烷基水杨酸铅的油溶性最好 ;月桂酸铅的抗磨性能和抗极压性能最好 ,油酸铅的减摩性能最好 .通过对铅盐分子结构及相应钢球磨斑表面进行扫描电子显微镜和 X射线光电子能谱分析 ,发现铅盐对基础油摩擦学性能的改善归因于摩擦过程中有机铅盐在摩擦副表面形成一定强度的吸附膜以及部分吸附膜转化为铅氧化物膜的摩擦化学反应 .铅盐烷基链结构的不同使其在摩擦副表面的吸附量和吸附强度不同 ,从而影响润滑油膜的化学组成和物理性能 ,并进而产生摩擦学性能差异

Investigation of Tribological Behavior and Action Mechanism of Organic Lead Salt as Lubricating Oil Additives

Five carboxylic lead salts, namely, lead laurate (LL), lead oleate (LO), lead naphthenate (LN), lead stearate (LS) and lead alkylsalicylate (LAS) were synthesized by in situ fusion process, precipitation process, and microwave assisted method in 200SN base oil. Their tribological properties as friction reducing, anti wear and extreme pressure additives for lubricating oil were evaluated with a four ball machine. The action mechanisms of the additives were discussed as well. The results indicate that the oil solubility, anti wear and friction reducing ability, and extreme pressure load carrying capacity of the compounds as additives are dependent on the molecular structure. LL and LAS exhibit the best oil solubility, LL possesses the best anti wear and extreme pressure properties, while LO shows the best friction reducing ability. The difference in the alkyl group of the organic lead salts accounts for the difference of their adsorption on the frictional pair surface and hence the strength of the boundary lubricating film as well. This leads to the difference in the chemical composition and physical properties of the boundary lubricating film and thus the tribological behavior as well. Namely, the alkyl groups with stronger absorption ability usually give better tribological behavior. The formation of PbO in the boundary lubricating film contributes to improve the wear resistant ability and load carrying capacity.