Improved corrosion resistance and biocompatibility of AZ31 alloy by acid pickling pretreatment and (H plus ) hydroxyapatite/chitosan composite coating

As a new generation of biodegradable hard tissue repair implants, the excessive corrosion rate in a liquid environment and the potential cytotoxicity of magnesium and its alloys have limited their further clinical ap-plications to some extent. Because of this, in this study, a network-like porous structural surface with relatively uniform pore size was designed and prepared on the surface of AZ31 magnesium alloy by acid etching treatment, and the HAp prepared on this surface exhibited the advantage of high interfacial bonding strength, and the (H+) HAp /CS composite coating was prepared by using biocompatible CS as the sealing layer of the HAp coating pores, and the acid etching was investigated by electrochemical tests. The corrosion resistance of HAp prepared under acid-etching conditions and HAp prepared on AZ31 surface without acid-pickling treatment were inves-tigated by electrochemical tests, while the composite coatings were characterized by X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and EDS, and further tests such as electrochemical experiments, hydrogen precipitation experiments and cytocompatibility assessment concluded that the composite coating has good corrosion resistance, can effectively reduce the degradation rate of magnesium alloy, low magnesium ion precipitation concentration in the cell culture process has less effect on cell growth, and the coating can promote the attachment and proliferation of BMSCs osteoblasts, showing excellent cytocompatibility. Therefore, this study provides a new idea for the design of AZ31 surface morphology and the improvement of corrosion resistance and biocompatibility of AZ31 magnesium alloy, which is beneficial to promote the further development of AZ31 magnesium alloy as a bone repair material.