极压、抗磨剂对锂基润滑脂抗磨减摩性能的影响

THE INFLUENCE OF EXTREME PRESSURE-ANTIWEAR ADDITIVES ON THE ANTIWEAR AND FRICTION-REDUCTION PROPERTIES OF LITHIUM-BASE GREASE

采用四球和SRV试验机分别考察了不同浓度的3种添加剂（T321,TCP和T202）在不同酸碱性的锂基润滑脂中的极压、抗磨性;并分别采用扫描电子显微镜和X射线光电子能谱仪观测钢球的磨斑表面形貌和分析钢球磨斑表面的主要元素。研究发现,在适宜的酸碱性下,硬脂酸对含3种添加剂的锂基润滑脂的抗磨、极压性有增效作用。添加3%T202或1%~2%T321或2%TCP的弱酸性锂基润滑脂相应的摩擦系数最低、磨斑直径最小、磨损量最少、PD或PB值较高。而且,含3种不同添加剂的锂基润滑脂润滑下的钢球磨斑形貌有明显区别,其减摩抗磨机制为在摩擦表面生成含硫、磷、锌等元素的化学沉积膜。

The effects of three kinds of additives （Sulfurized olefin, triphenyl phosphate and zinc dialkyl dithiophates） on the extreme pressure and antiwear properties of different acid-alkali lithium-base grease were investigated by four-ball wear tester and an oscillating SRV apparatus. Morphology of wear scar of steel ball was observed by using SEM. Chemical states of typical elements on the wear scar of steel ball were analyzed by means of XPS. It was found that the stearic acid could improve the extreme pressure and antiwear performance of the three additives in subacidity lithium-base grease. Subacidity lithium-base grease respectively doped with 3% zinc dialkyl-dithiophates （ZDDP, T202）, 1%--2% sulfurized olefin （T321）, or 2% triphenyl phosphate （TCP） exhibited preferable properties of antiwear and friction reduction, and good load-carrying capacity. SEM images of wear scar of steel ball revealed there were obviously topographical differences in the three additives-based antiwear films. The mechanism of antiwear and friction reduction of the three additives was that the chemical sediment of sulfur, phosphorus, zinc and calcium occurred on surface of the steel ball to form a chemical deposit film.