Effect of iron-enriched aluminum surface fabricated with fine particle peening on tribological behavior under oil lubrication

Lubricants generally contain various additives to improve tribological performance. Zinc dialkyldithiophosphate (ZnDTP) is a widely employed lubricant additive that aims to suppress wear, especially under severe contact conditions. Although it is a common additive, it has been reported that its effectiveness was insufficient when applied to sliding components made of aluminum. In this study, the authors proposed a novel surface modification process that encourages the performance of ZnDTP on aluminum sliding components. To enrich the aluminum surface with Fe element, which has been believed to react with ZnDTP to form anti-wear tribofilm during sliding, fine particle peening (FPP) that can transfer shot particle elements onto the peened surface was focused on. The result revealed that Fe-rich specific microstructures were created along the aluminum surface by FPP using steel shot particle. The ball-on-disk reciprocating sliding test under the presence of ZnDTP realized that the peened surface enriched with Fe element could show reduced wear when ZnDTP-derived tribofilm successfully worked. The possibility of the transferred Fe elements to act as an adsorption site of ZnDTP and contribute to the formation of anti-wear tribofilm.