Browsing by Subject "corrosion"

Now showing 1 - 3 of 3
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    Effect of microarc oxidation time on electrochemical behaviors of coated bio-compatible magnesium alloy
    (2014) Liu, Jiayang; Zhang, Wiejie; Zhang, Hanying; Hu, Xinyao; Zhang, Jing
    Magnesium alloys are newly promising biomaterials with potential application of human bone replacement. However, there is a drawback due to their high corrosion rates. In this study, AZ31 magnesium alloys were coated using microarc oxidation (MAO) process. Two oxidation durations, 1 minute and 5 minutes, were used. The samples were immersed in the simulated body fluid (SBF) for up to seven days. Then the electrochemical behaviors of the two samples were comparatively investigated. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) experiments were used. The results show that the 5-minute MAO coated sample had a better corrosion resistance than the 1-minute MAO coated sample. The study shows processing parameters, e.g., oxidation time, can be used to design an optimized MAO-coated magnesium alloy with controlled corrosion rates.
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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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    Self-Healing Corrosion Resistant Coatings
    (Office of the Vice Chancellor for Research, 2014-04-11) Jones, Alan; Ye, Lujie
    According to the U.S. Federal Highway Administration, the annual cost of corrosion in the United States is estimated at $276 billion. The most common way to protect materials from corrosion is with coatings, including organic (paint), ceramic and metallic coatings. During use, micro-cracks form in coatings resulting in exposure to the environment, which can lead to catastrophic failure of critical components. Our group is developing low-cost self-healing technology to significantly extend the service life of coatings and the components they protect. Potential healing agents were evaluated and an air-drying triglyceride (linseed oil) was identified as the candidate healing agent. Self-healing coatings are fabricated using urea-formaldehyde encapsulated linseed oil and are evaluated for mechanical performance, corrosion resistance, and self-healing performance. Research into optimization and long term durability and performance of low-cost self-healing coating materials is ongoing.