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An Investigation on Zirconia Nano-particles Coating Deposited on Magnesium AZ91 alloy Using Electrodeposition Method

Amiri, Hamed | 2014

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 46657 (07)
  4. University: Sharif University Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Afshar, Abdollah
  7. Abstract:
  8. Recently magnesium alloys have shown great potential as biodegradable metallic implants. However, due to high corrosion rate in the body environment, these alloys would be degraded before the tissue healing time period. Therefore corrosion resistance of these alloys has to be improved in order to be used in biological environments. In the present work, supposing improvement of corrosion properties of magnesium AZ91D alloy, the alloy has been coated with biocompatible nano-Zirconia particles using Electrophoretic deposition method and the effects of deposition parameters such as bath agitation, Zirconia concentration, current density and duration of deposition process on the properties of the coating have been investigated. Phase analysis has been carried out using X-ray Diffraction method. Electrochemical investigations to assess corrosion properties of the coatings including Potentiodynamic polarization, Electrochemical Impedance Spectroscopy and immersion test have been carried out in Simulated Body Fluid (SBF) at 37 degrees centigrade and pH 7.40. Morphology has been characterized using scanning electron microscopy and phases, formed on the coated samples after a week of immersion test, have been detected using Energy-dispersive detector. In order to investigate biocompatibility of the samples, SBF solutions of the immersion test after a week of immersion have been characterized using Atomic absorption spectroscopy. In conclusion, the deposited coating with a thickness of 35 micrometers reduced the current density of the corrosion from 18.21 µA/cm2 to 0.50 µA/cm2 and increased the polarization resistance from 355 KΩ to 3500 KΩ. Biocompatibility investigations also indicated that during the use of AZ91D alloy as an implant there would not be a problem related to the neurotoxicity of Aluminum and the coating/substrate complex system showed a proper biocompatibility. Furthermore, the adhesion of the coating with the best corrosion have been measured 11 MPa
  9. Keywords:
  10. AZ91 Magnesium Alloy ; Electrodeposition ; Electrophoretic Deposition ; Zirconia Bioceramic ; Biocorrosion

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