Microstructure, Corrosion Resistance and Biocompatibility of Biomimetic HA-Based Ca-P Coatings on ZK60 Magnesium Alloy

Recently, magnesium alloys have attracted much attention as a metallic biodegradable implant because of their excellent biocompatibility and mechanical compatibility. However, magnesium has a poor corrosion resistance due to its active chemical properties, which limited the application in orthopedic surgery. In this work, Ca-deficit hydroxyapatite (HAp) coatings were prepared on the ZK60 magnesium alloys by a biomimetic method. The revised SBF solutions with pH value of 5 similar to 7 and Ca/P ratio of 1.67 were used. The coatings were composed of ball-like CaP particles with the Ca/P ratio of 0.86 similar to 1.24. Electrochemical corrosion, in vitro immersion and cytotoxic tests were conducted to evaluate the corrosion resistance and biocompatibility. The corrosion resistance and biocompatibility of the coated samples were greatly improved comparing with that of the uncoated sample. For the samples fabricated at different pH values, the sample coated from the solution with pH of 6 has the best corrosion resistance and biocompatibility.