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Effect of Nano Alumina Particles Addition in Electrolyte by Micro arc Oxidation Process on Titanium Substrate

Sarbishei, Sahand | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43679 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Faghihi-Sani, Mohammad Ali; Mohammadi, Mohammad Reza
  7. Abstract:
  8. Titanium and its alloys have wide applications in industry and recently researches have been expanded in this area. The main reasons are unique features of titanium such as biological behavior, corrosion resistance and high strength to weight ratio. The fundamental problem of titanium is low wear resistance that leads to be worn in industrial applications. For more efficiency of titanium, extensive efforts have been made for solving this problem, one of the best solutions is coating.Micro Arc Oxidation (MAO) is a novel method to create ceramic coatings on metals to improve wear and corrosion resistance. In this research nano alumina particles were added to electrolyte to create alumina-silicate composite coating on titanium. Effects of coating time process, current density and nano alumina concentration on morphology, composition, wear resistance and corrosion behavior of the coatings were studied. Results showed that nano alpha-alumina particles with high hardness (9 Mohs) had a significant role in improving the wear properties of the coating and also by filling the porosities of discharge channels, can increase the corrosion resistance of the coating. Thickness and weight gain of the coating is increased by increasing time and current density. With increasing coating time process, small pores are filled by nano particles but large pores get larger, so there is a optimum percent for minimum porosity in the coating. Energy of discharge channels are boosted with increasing current density and that causes more nano particles attached to the surface. Increasing the concentration of alumina nanoparticles in the electrolyte leads to filling pores by more nano particles. Corrosion and wear resistance of optimum sample is 93 and 2.5 times (respectively) greater than titanium substrate.
  9. Keywords:
  10. Wear Resistance ; Corrosion Resistance ; Micro Arc Oxidation (MAO) ; Titanium ; Alumina-Silicate Composite Coating

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