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The Structure and Corrosion Behavior of Synthesized Zn-SiO2 Nano-composite Coating by Sol-Gel Method

Razavizadeh, Omid | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: English
  3. Document No: 42961 (57)
  4. University: Sharif University of Technology, International Campus, Kish Island
  5. Department: Science and Engineering
  6. Advisor(s): Ghorbani, Mohammad
  7. Abstract:
  8. Zinc–silicanano-composite coatings were produced by successive dip coatand sintering procedure from different sol-gel solutions. The surface and cross-sectional morphologies of Zn-SiO2 nano-particles (NPs) were examined using field emission scanning electron microscopy (FE-SEM). Corrosion resistance evaluated by means of polarization and electrochemical impedance spectroscopy showed that even thin films of Zn-SiO2 in orders of 200 nm can have corrosion rates as low as conventional hot dip galvanized steels. Multi-layers coatings have been studied and showed that 10 layers coating with the thickness of 2m has the lowest corrosion rate with the passive region in anodic branch. Corrosion potential measurement showed that zinc NPs have different behavior in comparison to crystalline zinc and act nobler than steel substrate. Results obtained from roughness and bearing properties by atomic force microscopy (AFM) suggest that the coating have high abrasion resistance with low coefficient of friction. Micro hardness was evaluated above 1000 HV5 for 10 layers coating. Based on results from electrochemical measurement and the micrographic characteristics of zinc–silica NPs after corrosion testing, a probable corrosion mechanism is proposed.

  9. Keywords:
  10. Sol-Gel Method ; Nano-Composite Coating ; Corrosion ; Hardness ; Zinc-Silica Nanocomposite

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