表面修饰硼酸盐润滑油添加剂的摩擦化学作用机制

Study on Tribochemical Mechanisms of the Modified Borate Additives

采用 X射线光电子能谱仪研究了表面修饰硼酸盐润滑油添加剂在钢球表面形成的表面膜的元素组成和化学状态 ,并考察了摩擦化学反应膜的结构和化学作用机制 .结果表明 :在不同油润滑条件下 ,硼酸盐润滑油添加剂均与钢球磨损表面发生了相互作用 ,并形成主要由吸附膜和摩擦化学反应膜组成的复杂表面膜 ;摩擦化学反应膜中所含元素的化学状态及其含量与试验负荷有关 ,且沿反应膜深度方向而变化 ,即由表及里 ,Fe与 B、N及 O等形成的无机化合物的含量逐渐增加 。

The N containing compound modified borate as an oil additive was prepared.The concentration of boron is about 7.2 wt.%. The particle diameter of the N containing compound modified borate is less than 0.5 μm.Liquid paraffin was used as base stock.The tribological behavior of the sample oils containing the N containing compound modified borate at different loads was examined using a four ball tester.The steel balls of diameter 12.7 mm and HRC59 61,which were cleaned in an ultrasonic bath with ethanol for 10 min before the friction and wear test,are made of GCr15 bearing steel (similar to SAE52100 steel).The conditions adopted in the test were as follows:loads 196 N and 392N ,test duration 30 min,revolution 1 450 per minute,test temperature 25℃.The element composition,chemical states and the structure of the tribochemical film on the worn surface of steel lubricated with liquid paraffin containing surface modified borate were investigated by means of X ray photoelectron spectroscopy(XPS). The XPS analysis was carried out on a VG ESCA LAB 210 system using MgK α excitation.The electron energy analyzer was operated at a pass energy of 20 eV.The results show that the modified borate additive showed difference in terms of tribochemical action mechanisms under different loads.In other words,the chemical states and content of the typical elements in the tribochemical reacting film on the worn steel surface are dependent on the load applied.The content of the inorganic compounds composed of FeB,FeO,FeB and FeN increases from the outside to the inner layer of the film,while that of the organic compounds decreases.