基于分子动力学理论制备含氮磷硼酸酯添加剂及其摩擦学性能

摘要

利用分子动力学(MD)理论设计合成了一种新型含氮磷硼酸酯极压抗磨添加剂NBPE，分别采用元素分析仪和红外光谱仪(FTIR)对分子结构进行表征。采用热重分析法(TG)和饱和蒸汽法分别考察化合物的热稳定性与水解稳定性；采用四球摩擦磨损试验机考察NBPE的含量对润滑油摩擦学性能的影响；利用立式万能摩擦磨损试验机研究不同润滑条件下钢−铜摩擦副的摩擦磨损性能；利用扫描电子显微镜(SEM)观察试样表面磨痕形貌，利用能谱分析仪(EDS)分析磨斑表面附着物组成。结果表明：NBPE是一种具有良好热稳定性、水解稳定性和优异的极压、抗磨性的润滑油添加剂；添加剂在金属表面发生摩擦化学反应形成摩擦化学产物是提高其极压、抗磨性能的根本原因；当润滑油中 NBPE 的含量为0.15%(质量分数)时，润滑油具有最佳的极压、抗磨性能，其油膜强度提高了148%，磨斑直径降低了23.2%；在钢−铜摩擦过程中，摩擦因数和铜磨损率分别降低了59.4%和45.2%，获得光洁度较好的铜表面。%A new extreme pressure and anti-wear additive of nitrogen-and phosphorus-containing boric acid ester (NBPE) was designed and synthesized by molecular dynamics method and characterized by infrared spectroscopy and element analysis. The thermal stability and hydrolytic stability of compounds were examined by thermogravimetric analyzer and saturated steam method, respectively. The effect of the NBPE lubricants content on the tribological behavior was investigated using four-ball friction and wear tester. The friction and wear properties of copper-steel friction pairs under different lubrication oils were measured by vertical universal test machine. The surface morphologies of the grinding crack were observed by scanning electron microscopy (SEM), and the composition of its surface attachments was analyzed by energy dispersive spectrometry (EDS). The results show that NBPE has good thermal stability and hydrolytic stability, and it also exhibits excellent extreme pressure, anti-wear properties as additives in lubricating oils. The lubricant exhibits excellent extreme pressure and wear-resistance attribute to the tribochemical reaction of nitrogen-containing boric acid ester with the sliding surface. When the content of NBPE is 0.15% (mass fraction), it has the best extreme pressure and anti-wear performance, the maximum non-seizure load (p B ) value is increased by 148%and the wear scar diameter is decreased by 23.3%. In steel-copper friction process, the coefficient of friction and the wear rate of copper are also reduced by 59.4%and 45.2%, respectively. And a good copper surface can be obtained.