Study on the corrosion resistance of SiC particle-reinforced hydroxyapatite-silver gradient bioactive ceramic coatings prepared by laser cladding

Hydroxyapatite (HA) bioactive ceramic coatings for artificial joints require longevity for use in the human body. However, microcracks in the coating gradually expand under the action of body fluid erosion, causing the coating to crack and potentially fall off. To prevent the corrosion shedding of the HA bioactive coating in body fluid, we developed a method based on our previous three-layer gradient HA-Ag bioactive ceramic coatings. Herein, a SiC particle-reinforced HA-Ag bioactive ceramic coating was prepared on the surface of the femoral stem of a titanium artificial hip joint using coaxial powder feeding laser cladding. Through electrochemical corrosion tests, the effect of the addition of the SiC reinforcement phase on the corrosion resistance of the coating was studied, the corrosion rate of the coating in simulated body fluid (SBF) was analyzed, and the mechanism of the SiC reinforcing phase in improving the corrosion resistance of the coating was revealed. The results show that the SiC particles doped in HA bioactive layer improved the corrosion resistance of the HA bioactive layer by enhancing the fracture toughness of the coating through crack deflection and bridging, improving the corrosion potential, impedance, and capacitance of the coating, and inhibiting charge transfer between the coating surface and SBF. In summary, the optimal performance of the bioactive ceramic coating was obtained by doping 15 wt% SiC particles. Therefore, the doping of SiC particles provides a technical approach to further enhance the service performance of bioactive ceramic coatings.