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Electrodeposition and Characterization of Zn-Ni-Mn Coatings

Esmaeeli, Mehdi | 2020

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53266 (07)
  4. University: Sharif University of Technology
  5. Department: Materials Science and Engineering
  6. Advisor(s): Ghorbani, Mohammad
  7. Abstract:
  8. In this study, the electrochemical precipitation of three-component zinc-nickel-manganese coating on st37 steel substrate from chloride bath was investigated. Cyclic voltammetry results showed that the presence of ammonium thiocyanate complexer had a positive effect on the stability of precipitated manganese. Also, in order to evaluate the optimal coating conditions, the precipitation process at voltages of -1.4, -1.5 and VSCE -6.6, concentration of zinc 0.3 M, concentration of nickel 0.15 M and concentrations of manganese 0.15, 0.3 And 0.45 M and temperatures of 25, 40 and 55 .C. The results of X-ray energy diffraction spectroscopy, atomic absorption spectroscopy and X-ray diffraction of the coatings showed the successful deposition of Zn-Ni-Mn three-component coating. Examination of the morphology of the coatings showed that the morphology of the coating is three-part spherical and with increasing manganese content of the coating, the grain size decreases. Studies have also shown that with increasing potential, temperature and concentration of manganese, the amount of manganese in the coating and corrosion resistance increases; According to the results of polarization test in 3.5% sodium chloride solution, the highest corrosion resistance is related to the coating created from the bath with 0.45 M manganese ion at a voltage of -6.6 VSCE and a temperature of 55 .C. Under these conditions, the corrosion current density of st37 steel substrate was reduced from A.Cm-2 4-10 × 1 to A.cm-2 6-10 × 9 and a coating with maximum manganese content was deposited. (11.58% wt% manganese and 14.83% wt% nickel)
  9. Keywords:
  10. Manganese ; Corrosion ; Zinc-Nickel-Manganese Alloy Coating ; Electrochemical Precipitation ; Chloride Bath ; Electrodeposition

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