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Abstract: Ceramic coatings were fabricated on ZK60 magnesium alloy by microarc oxidation (MAO) with different negative voltages. The coating degradability and bioactivity were evaluated by simulated body fluid (SBF) soaking test. A scanning electron microscope (SEM) and an X-ray diffractometer (XRD) were employed to characterize the coating morphology and phase composition. The electrochemical workstation was used to investigate the electrochemical corrosion properties of the samples. The results show that the coating growth mechanism can be influenced by the introduction and increase of negative voltage through affecting the direction and speed of ions transferring. With increase of negative voltage in the range of 0–100V, the coating electrochemical corrosion property is improved, the coating degradation rate is reduced, and the combination property of coating corrosion resistance and apatites forming ability is enhanced. [Copyright &y& Elsevier]

Abstract: Corrosion and biological properties of microarc oxidized calcium phosphate (CaP) coatings on Mg–Zn–Zr alloy were improved by optimizing negative power density parameters. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) were employed to characterize the coating morphology and phase composition. The in vitro cytotoxicity and systemic toxicity tests were carried out to evaluate the coating biocompatibility. The degradability and bioactivity of the coatings were determined by in vitro simulated body fluid (SBF) immersion test. The coating microstructure, thickness and growth rate can be influenced by negative power density through changing direction of ions movements, rate of ions exchanges and affecting formation of plasma. The CaP coatings reduced the substrate degradation rate. Calcium phosphates, such as hydroxyapatite (Ca10(PO4)6(OH)2, HA) and calcium pyrophosphate (Ca2P2O7, CPP), etc., were induced after 30 days SBF immersion, indicating that the coatings have bioactivity. The CaP coatings have no toxicity to cell and living mice, indicating that the coatings are safe to serve as implants. [Copyright &y& Elsevier]

Highlights: [•] Bioactive CaP coatings are successfully formed on ZK60 magnesium alloy. [•] Different phosphates do not change the phases of CaP coatings. [•] Fluorides released during the SBF immersion do not cause observed adverse effect. [•] CaP coatings E3 show lower degradation rate, better bioactivity and biocompatibility. [Copyright &y& Elsevier]