Effects of laser melting and surface texture on the frictional performance of medical Co–Cr–Mo alloy

Cobalt–chromium–molybdenum (Co–Cr–Mo) alloy is widely used in orthopedic implants owing to its exceptional mechanical properties. However, its tribological performance remains the critical limiting factor for service longevity. To address this challenge, this study employed laser surface melting combined with texture patterning to enhance the alloy’s frictional characteristics. The effects of these surface treatments on microstructural evolution, hardness enhancement, and tribological behavior under both dry sliding and simulated body fluid lubrication conditions were systematically examined. Results demonstrate that laser melting produced a refined microstructure characterized by cellular and columnar crystals, accompanied by a 14.2% increase in surface hardness compared to untreated specimens. Under dry friction conditions, the laser-melted surface exhibited an 8.7% reduction in friction coefficient relative to the untreated surface, whereas single-texture treatment unexpectedly increased the friction coefficient by 11.7%. Significantly, the synergistic combination of melting and texturing achieved a 20% friction coefficient reduction. Under simulated body fluid lubrication, both surface modification techniques improved wear resistance, with the hybrid treatment demonstrating optimal performance. Individual texture and melting treatments reduced friction coefficients by 9.8% and 12.3%, respectively, while the composite surface treatment yielded an 18.1% reduction. These surface engineering strategies significantly improve the reliability and operational lifespan of medical-grade Co–Cr–Mo alloys in clinical applications.