Microstructural characterization of laser-irradiated bulk copper under dry sliding conditions

Abstract

The functionalization of surfaces for tribological applications is still a challenging task. There are numerous techniques for improving the friction and wear behaviour of metallic surfaces ranging from different coatings to textured surfaces. A promising approach for textured surfaces is the usage of laser interference patterning by a pulsed nanosecond Nd:YAG laser. Copper samples have been laser patterned using the laser interference metallurgy process. The resulting topographies were evaluated by white light interferometry and scanning electron microscopy in order to study the homogeneity of the structures at both macro- and micro-scales. Electron backscattering diffraction and transmission electron microscopy were performed in order to study the microstructural and oxide layer modifications induced by laser irradiation. Electron backscattering diffraction measurement did not show fine grains but a small proportion of misorientation due to the high quenching rate. Transmission electron microscopy did not allow to observe oxide layers. The friction and wear behaviour of bulk copper samples structured by laser interference metallurgy have been studied under dry sliding conditions using a tribometer in linear reciprocating sliding mode. Friction coefficient measurements revealed that patterned surfaces present a reduction in friction of up to 70% compared to untreated samples due to their good bearing properties and the reduction of the contact area.