Loading...

Characterization of Ceramic Coating Synthesized on Magnesium Alloy Substrate by Plasma Electrolytic Oxidation Process

Rafizadeh, Ehsan | 2011

762 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 41405 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Faghihi Sani, Mohammad Ali
  7. Abstract:
  8. Plasma electrolytic oxidation (PEO) is currently recognized as an effective coating method on active metals such as magnesium. In this method, through occurrence of strong electric discharges on the surface of the anode accompanied by electrochemical and thermo-chemical reactions at plasma environment, a relatively thick ceramic coating with complex compounds grows on the metal surface which significantly improves its properties. Regarding the influence of PEO electrical parameters on the morphology and other properties of the coating, the objective of the present study is to prepare a quality ceramic coating on AZ31 magnesium alloy substrate via setting the process parameters, such as current density and frequency on pre-defined values and finally, conclude a comprehensive trend of the effect of these parameters on coating properties such as morphology and phase composition and other characteristics of the coating. For this purpose, alkaline electrolyte containing sodium silicate, sodium hydroxide and sodium fluoride was used to produce ceramic coating on AZ31 magnesium alloy substrate. The process was conducted by setting the value of current density from 4.7 to 17.5 A/dm2, pulse frequency from 50 to 1800 Hz and treating time from 3 to 15 minutes. The results showed that by increasing the pulse frequency, due to shortening of pulse duration, mean diameter of the pores on the surface of the coating reduced from 31.3 to 1.3 μm. It was also observed that formation of thick and dense coating, by using high current density along with high pulse frequency, improved corrosion resistance up to 3 orders of magnitude and severely reduced wear rate
  9. Keywords:
  10. Ceramic Coating ; Magnesium Alloy ; Corrosion Resistance ; Surface Morphology ; Pulse Frequency ; Plasma Electrolytic Oxidation

 Digital Object List

  • محتواي پايان نامه
  •   view

 Bookmark

No TOC