Hydroxyapatite coating performance enhancement and characterization for Mg-Zn-Ca-Y alloys for biomedical application

Although magnesium (Mg)-based alloys have attracted considerable attention for use in temporary biomedical implants due to their biocompatibility and biodegradability, their clinical application has been limited by their inherently high degradation rate in physiological environments. To mitigate this limitation, hydroxyapatite (HAp) coatings were applied to Mg-4Zn-0.2Ca-(x)Y (yttrium) (x = 3, 6, 9, 12) % wt. alloys using a thermal coating technique aimed at enhancing corrosion resistance. Three different HAp coating thicknesses—50 μm, 100 μm, and 150 μm—were deposited onto the magnesium alloy substrates. Characterization via field emission scanning electron microscopy (FE-SEM) and energy-dispersive X-ray spectroscopy (EDX) confirmed the formation of a dense, homogeneous, and compact HAp coating layer. The in vitro degradation tests revealed a substantial improvement in corrosion resistance, attributed to the protective nature of the HAp barrier. Furthermore, bioactivity assessments conducted in Hank’s balanced salt solution indicated the formation of a uniform and adherent layer of bone-like apatite on the coated surfaces, affirming the alloy’s potential for osteointegration. The application of HAp coating not only enhanced the corrosion resistance but also significantly improved the compressive and tensile strength of the magnesium alloy. Overall, the coated Mg-4Zn-0.2Ca-(x)Y alloys exhibit promising characteristics for use in temporary orthopedic and biodegradable implant applications, owing to their improved mechanical performance and superior resistance to physiological degradation.