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Electroplating Nano Crystalline Acidic Zinc for Reduction of Corrosion Rate

Bahrampour, Saba | 2012

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 43675 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Baghalha, Morteza
  7. Abstract:
  8. In this project, nonocrystalline zinc coatings with grain sizes within the range of 22-63 nanometers were produced on yellow-brass plates by electroplating in an acidic chloride bath in the presence and absence of additive has been investigated.current densities and bath stirring speeds change from 2 to 6 A/dm2 and 0 to 400 rpm respectively.To determine crystallite size, X-ray diffraction technique (XRD) was utilized;it was found that the use of additive has effectively refined the grain size and optimum current density is 3 A/dm2 to reach this objective.. it was observed that grain size increased continuously with increase in bath stirring speed. The results coming from XRD tests were compared with FESEM tests in order to verify their reliability; Furthermore, the Tafel slope was calculated at 0.12 V using the line slope, which is a reasonable figure in electrochemical systems. At last,electrochemical behavior of the electrodeposited specimens was evaluated by conducting polarization tests in 3.5wt% NaCl solution. These tests results demonstrated that corrosion rate of thecoatings which had been prepared in the stationary system decreased with decrease in grainsize. However, by applying turbulence to the bath, the surface became more vulnerable to corrosion and increase in turbulence intensity resulted in a higher corrosion rate in the
    polarization tests.
  9. Keywords:
  10. Nanocrystal ; Grain Size ; Electroplating ; ZINC ; Coverage ; Corrosion Rate ; Zinc Electroplating ; Current Density

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