Comparison of anodic dissolution, surface brightness and surface roughness of nanocrystalline nickel coatings with conventional decorative chromium coatings
The effects of saccharin concentration and pulsating peak current density on corrosion behaviour, surface brightness and surface roughness of nanocrystalline nickel coatings were investigated and the results were compared with those of the conventional decorative chromium coatings. The average grain size of nanocrystalline nickel coatings was determined using X-ray diffraction patterns. Corrosion behaviour was evaluated using electrochemical impedance spectroscopy (EIS) in a 0.6 M sodium chloride solution. A gloss meter and a Suftest device were used to evaluate surface brightness and roughness. Corrosion resistance and brightness of the nanocrystalline nickel coatings increased with increasing the saccharin concentration in the bath. Moreover, brighter nanocrystalline nickel coatings were obtained with increasing the peak current density. In addition, all nanocrystalline nickel coatings were more corrosion resistant than chromium coatings. Those nanocrystalline nickel coatings with average grain sizes of less than 38 nm were brighter and had smoother surfaces than conventional decorative chromium coatings.
KeywordsNanocrystalline nickel Decorative chromium Corrosion Brightness
The financial support for this research (grant number 86-GR-ENG-62) given to Dr. M.E. Bahrololoom by the Research Committee of Shiraz University is gratefully appreciated.
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