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Micro Arc Oxidation Coating on Magnesium Alloy AZ31 and Study its CorrosionBehavior in Physiological Solution

Salami, Behrooz | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42617 (07)
  4. University: Sharif University of Technology
  5. Department: Material Science and Engineering
  6. Advisor(s): Afshar, Abdollah
  7. Abstract:
  8. Magnesium and its alloys have been used as biodegradable implements in recent years. However Magnesium implements may corrode in the body before the natural healing process of the damaged tissue. MAO process was studied in order to reduce primary corrosion of Magnesium alloy in Simulated Body Fluid (SBF). MAO coating was created on AZ31 alloy in a nontoxic alkaline-silicate solution at DC current densities of 5, 10, 15 and 20 mA/cm2 for 30 minutes and the current was in form of 20-10-5 mA/cm2 steps that each were applied for 10 minutes. The maximum corrosion resistance was observed for the mentioned step applied current in a 30g/l Sodium Silicate solution. Furthermore the effects of adding surfactant to the electrolyte and sealing the cover using sol-gel method were studied. Adding 0.25 g/l of surfactant decreased the corrosion coating current from 10.8 to 0.69 µA and sealing the coating by Titania sol decreased the corrosion current to 0.14 µA. In order to study the morphology of the coating a Scaning Electron Microscopy which was equipped EDS detector was used. XRD was used to determine coating phases. Corrosion resistance of the sample was measured using potentiodynamic polarization and electrochemical impedance test in SBF at temperature of 37 degrees centigrade and pH of 7.4
  9. Keywords:
  10. Magnesium Alloy ; Sol-Gel Method ; Biodegradability ; Simulated Body Fluid (SBF) ; Micro Arc Oxidation (MAO)

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