Effects of Sr incorporation on surface structure and corrosion resistance of hydroxyapatite coated Mg-4Zn alloy for biomedical applications

Abstract Hydroxyapatite (HA) and strontium (Sr) incorporated HA coatings with different Sr contents were prepared on Mg-4Zn substrates by electrochemical deposition method. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and electrochemical workstation were applied for the composition, phase constitution, morphology analyses and corrosion tests. The results reveal that the incorporation of Sr in coatings does not lead to dramatical change of functional groups and the crystal structure of the HA phase, but the crystal size and crystallinity decrease with increasing Sr content, which should be attributed to the lattice distortion and different occupancies of Sr and Ca ions. The 10SrHA@Mg-4Zn samples show the lowest corrosion current density and the highest corrosion potential, and also exhibit the lowest amount of hydrogen evolution among all coated samples.