Positive effect of laser structured surfaces on tribological performance

Abstract

In recent years laser surface structuring has emerged as a viable tool to enhance surface function-ality. In this study, an ultrashort pulsed laser is used to create advanced surface structures in order to improve the tribological properties of steels. The objective is to decrease friction and wear especially for the mixed lubrication regime in which body and counterbody are in contact. We state the hypoth-esis that the high flow resistance in small channels helps to hold the lubricant in the tribocontact and therefore separates contacting asperities. Direct Laser Writing and Direct Laser Interference Pattern-ing methods are used to create cross-like structures of different channel sizes. Tribological properties of these structures are evaluated by means of a ball-on-disc tribometer. The surface structures and the wear behavior are analyzed with confocal microscopy. The results show a decrease of the coefficient of friction depending on the size of the channels. This behavior is discussed and compared to the hypothesis stated above.