Browsing by Subject "magnesium alloys"

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    The Electrochemical and Corrosion Behavior of Biocompatible Magnesium Alloy in simulated body fluid
    (Office of the Vice Chancellor for Research, 2014-04-11) Liu, Jiayang
    Magnesium alloys are newly promising biomaterials for human bone replacement or repair. However, magnesium alloy need more resistant to corrosion when it is implant in human body. In this investigation, protective microarc oxidation (MAO) coatings were generated on AZ31 Mg alloys in sodium phosphate electrolyte. The coating were produced under various applied voltage. The corrosion behavior of MAO was analyzed in this study. Optimization of the MAO controlling parameters would provide a higher corrosion resistance on AZ31 magnesium alloy. A seven-day-immersion test was applied on both uncoated Mg alloy and MAO-coated Mg alloy. To evaluate the corrosion properties, the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) experiments were used in this research. The degrading rate of the MAO-coated AZ31 alloy is reduced because MAO coating and the corroding product layer protected the substrate and declined the reflecting rate. The corrosion process and mechanism of MAO-coated AZ31 alloys in SBF were modeled according to the electrochemical corrosion results and surface analysis. Under optimized controlling parameters, it is to be sure that the MAO-coated AZ31Mg alloy is superior on material which are implanted in human body for biomedical applications.
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    Electrochemical Behavior of Micro-arc Oxidation Coated Magnesium Alloy in Cell Culture Medium
    (Office of the Vice Chancellor for Research, 2015-04-17) Liu, Jiayang; Zhang, Jing
    The electrochemical behaviors of MAO (micro-arc oxidation) coated AZ31 magnesium alloys immersed in cell culture medium are reported. Four different MAO processing times (1 minute, 5 minutes, 15 minutes and 20 minutes) were used to produce the MAO coatings on AZ31 magnesium alloy sample surface. After cell culture medium immersion tests, all samples demonstrate similar electrochemical behaviors regardless of MAO processing time, which is in contrast with immersion in simulated body fluids. The corrosion rates in cell culture medium are much lower than in simulated body fluid. This can be explained by the organic molecules in the cell culture medium and a dense passive layer formed on the samples surface, which prevent aggressive ions, such as chloride ions, from corroding the alloy substrate.