Surface Enhancement of CoCrMo Bioimplant Alloy via Nanosecond and Femtosecond Laser Processing with Thermal Treatment

With an aging population, the number of joint replacement surgeries is on the rise. One of the most common implant materials is cobalt–chromium–molybdenum (CoCrMo) alloy. Hence, the surface properties of this alloy have attracted increasing attention. In this study, nanosecond and femtosecond laser processing, followed by annealing, was employed to modify the CoCrMo surface. The effects of the treatment conditions on the surface morphology, structure, composition, hardness, roughness, contact angle, wear properties, and corrosion current were studied. Femtosecond laser processing with an energy density of 1273 mJ/cm2, followed by heat treatment at 160 °C for 2 h, produced laser-induced periodic surface structures (LIPSS) without altering the chemical composition of the alloy and rendered the surface superhydrophobic. In contrast, nanosecond laser treatment at higher laser energy densities promoted the formation of an oxide layer, which improved the hardness and corrosion resistance of the substrate. Overall, the CoCrMo samples processed using the femtosecond laser system exhibited superior corrosion and wear resistance, with a protection efficiency of approximately 92%.