Investigating the effect of Al and Mg dopedhydroxyapatite coating on improving the corrosion resistance of Mg substrates for implants application

considering its advantageous properties and resemblance to natural bone, hydroxyapatite (HA) coatings have garnered a lot of interest as a means of enhancing the corrosion resistance of magnesium implants. In this study, the efficacy of HA coatings doped with aluminum (AI-HA) and magnesium ($\mathrm{Mg}-\mathrm{HA}$) in enhancing the corrosion protection of magnesium AZ31 substrates for implant applications was investigated. Morphological analysis via Scanning Electron Microscope (SEM) confirmed the hydroxyapatite coating formation with a regular crystalline structure. Fourier Transform Infrared Spectroscopy (FTIR) offered further confirmation of the presence of HA coatings on the magnesium surfaces. Analysis using Electrochemical Impedance Spectroscopy (EIS) revealed that both AI-HA and Mg-HA coatings considerably enhanced the magnesium substrates’ resistance to corrosion when compared to the samples without coatings. Remarkably, the Mg-HA coating displayed superior corrosion protection, which can be attributed to its more homogeneous structure, reduced defects, and enhanced coverage, along with a stronger interface with the underlying magnesium substrate, in comparison to the AI-HA coating. With implications for the long-term functionality and therapeutic relevance of such biomedical devices, These results demonstrate the significant promise of magnesium-doped HA coatings as a practical means of improving the corrosion resistance of implants made of magnesium.