Effect of ion beam etching on the tribological performance of laser textured Co-Cr-Mo alloy

The micro-texture is a relatively well-established method for improving the tribological performance of Co-Cr-Mo alloy. Currently, to fabricate the micro-textures on the alloy surface, laser micromachining technology is the commonly used method. However, the low fabrication quality (such as irregular protrusions inside and on the edges of the micro-textures) caused by laser ablation limits the numerous application of laser surface textures. Therefore, a novel method of combining nanosecond (ns) pulse laser texturing with ion beam etching was proposed to prepare the micro-textures on the surface of Co-Cr-Mo alloy. The tribological properties before and after ion beam etching were tested by ball-disk friction wear test for three different micro-texture morphologies (grooved micro-texture (G); hexagonal micro-texture (H); concentric micro-texture (C)), and the micro-topography, mechanical properties and wettability of the ion beam/laser textured Co-Cr-Mo alloy were also investigated. The results showed that the friction coefficient and wear amount of the specimen surface were reduced after ion beam etching, and the ion beam/laser textured sample with hexagonal micro-textures showed the best wear performance, with the average friction coefficient reduced by 11.9 % and the wear amount of polyether ether ketone balls reduced by 14.9 %. The worn surface of the ion beam etched samples was relatively smooth, and the adhesive wear was also reduced. This report established the friction reduction model of ion beam/laser textured alloy and revealed the friction reduction mechanism of ion beam etching, providing a new idea of fabricating high-quality micro-textures to enhance the wear performance of artificial hip joints.