含硫硼酸酯中硫和硼在菜籽油中的协同减摩抗磨作用

合成了一系列含硫硼酸酯 ,在四球摩擦磨损试验机上考察了含硫硼酸酯化合物作为菜籽油添加剂的摩擦学性能 ,并用扫描电子显微镜和 X射线光电子能谱仪观察分析了钢球磨损表面形貌和表面膜中元素的化学状态 .结果表明 :含硫硼酸酯的摩擦学性能与其分子内硫和硼的含量密切相关 ;结构相似、元素组成不同的硼酸酯的抗磨效果与所含活性元素的数量不存在对应关系 ,而结构相似且 S和 P含量相同的硼酸酯的摩擦磨损行为相似 .钢球磨损表面分析结果表明 ,在摩擦过程中含硫硼酸酯与钢球表面发生摩擦化学反应 ,形成了含硫、硼、氧及碳等元素的表面保护膜

Synergistic Friction-reducing and Antiwear Action of Boron and Sulfur Elements in S-containing Borate Esters as Additive in Rapeseed Oil

Several S-containing borate esters and one borate ester based on boric acid and n-octanol were synthesized. The antiwear and friction-reducing properties of the synthetic compounds as additives in rapeseed oil were examined with a four-ball machine. The relationship between the additive structure and tribological properties was explored, while the lubrication mechanisms of the additives were investigated as well. Thus the worn surfaces of the steel ball lubricated with the additive-containing rapeseed oil were analyzed by means of X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It has been found that S-containing borate esters as additives in rapeseed oil at proper concentrations are effective in improving the antiwear and friction-reducing behavior of the rapeseed oil. The polar rapeseed oil experienced competitive adsorption and tribochemical reactions with the additive on the rubbing steel surface. However, the tribological behavior of the synthetic additives does not depend on the number of S atoms in the molecule. This implies that the tribological behavior of the additive might depend on the ratio of B to S in the additive molecule. This was confirmed by the result that the rapeseed oil containing additives having the same element composition and similar molecular structures exhibit similar tribological behavior. Therefore, it is inferred that there exists a synergistic effect between S and B atoms in the additive molecules.