Study on pH-dependence of electroosmosis effect and tribological behavior of water-based lubricants at friction interfaces

pH is usually used to assess the corrosion resistance and bacteriostasis of lubricants. In this paper, the electroosmotic and tribological characteristics of water-based lubricants at AISI 52100 steel/alumina ceramic friction interfaces are evaluated as an effect of pH value. A self-excited electric field (SEEF) generated by interface material frictional electrification induces the lubricant electroosmosis. Appropriately increasing the pH can improve the electroosmotic abilities of lubricants by changing the electrical double layer (EDL) structures at the friction material/lubricant interfaces. The lubricant tribological performance and penetrability are improved upon increasing the pH from 7 to 10. This is attributed to the fact that the lubricant with favorable electroosmotic performance shows a better penetrability, thus exerting an excellent effect of anti-friction and anti-wear.