Effect of polarization type on properties of Ni–W nanocrystalline electrodeposits |
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Authors: | S Kabi K Raeissi A Saatchi |
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Affiliation: | (1) Department of Materials Engineering, Isfahan University of Technology, Isfahan, 84156-83111, Iran |
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Abstract: | Nickel–tungsten nanocrystalline coatings were electrodeposited from a Watts type bath onto a copper substrate, at different
current densities selected from activation, mixed and diffusion controlled regions in the cathodic scan plot at room temperature.
The results confirm that tungsten codeposition proceeds via the adsorption and reduction of complexes produced in the bulk
of solution. The coatings obtained were single phase solid solutions and their grain sizes increased with current density.
A cauliflower-type surface morphology with highest hardness was obtained when the current density was in the activation controlled
region. The surface morphology obtained in the mixed controlled region was distorted, and then converted to a nodular morphology
in the diffusion controlled region. In the mixed control region, coatings with the highest corrosion resistance were obtained
due to the lowest exchange current density for water reduction. |
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Keywords: | Ni– W Coating Electrodeposition EIS Nanocrystalline Corrosion resistance |
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