Abstract
To investigate the structure and corrosion properties of micro-arc oxidation (MAO) coating on Mg-5Gd-1Zn-0.4Zr (GZ51K) alloys for biomedical application, the alloy was MAO-treated using silicate electrolyte system under current density of 400, 600 and 800 mA/cm2 respectively. The microstructure, surface analysis and corrosion resistance of samples were evaluated by scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, potentiodynamic polarisation, electrochemical impedance spectroscopy in SBF solution. The results indicate that the main phases of the MAO coatings were MgO, Mg2SiO4 and MgF2. With the increase of MAO current density, the thickness of the MAO coating decreased from 16.5 to 10.4 μm. When MAO current density is 400 mA/cm2, the specimen shows the best corrosion resistance with a four-order-of-magnitude decrease on Icorr ((1.95 ± 0.01) × 10−10 A/cm2), a four-order-of-magnitude increase on RP((7.67 ± 0.02) × 107 Ω cm2). Even though the thickness of the MAO coatings obtained with 600 and 800 mA/cm2 are very close, the corrosion resistance of the coating prepared under 800 mA/cm2 is better than that under 600 mA/cm2. Generally, MAO treatment can greatly slow down corrosion rate of the GZ51K alloy and keep uniform corrosion mode which is desirable for biodegradable implant applications.
Published Version
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