Abstract
Cu-Co alloys were electrodeposited on steel substrates from alkaline sodium tartrate electrolyte using direct and single pulsed current (DC and SPC, respectively). The electrodeposition bath was composed by 0.02 mol L−1 of CuSO4.5H2O, 0.10 mol L−1 of CoSO4.7H2O and 0.50 mol L−1 of Na2C4H4O6.4H2O. Using both kind of deposition processes, it was verified that the applied current density (j) affected the cathodic current efficiency (Ef), the copper and cobalt contents in the coatings (wt. % Cu and wt. % Co, respectively), the morphology and the anticorrosive performance of the coatings (based on the transfer charge resistance, (Rct) values). Comparing the results obtained for DC and SPC coatings, those produced by single pulsed current improved the Ef values and decreased the grain sizes. Concerning the conditions used in this work, the coating produced under the conditions of Experiment 4’, using jm = 40 A m-2 and SPC mode, presented 15.9 wt. % Co, the most compact morphology, the smallest grain size and the highest Rct value after 24 h of exposure in the saline medium.
Highlights
Cu-Co alloy coatings can be deposited on a substrate surface to produce functional coating/substrate systems presenting enhanced properties
Our goal is to evaluate the effects of the applied current density, using both direct current (DC) and pulsed current (PC) processes, Materials Research on the cathodic current efficiency (Ef), the metal contents in the coatings, the morphology and microstructure of the coatings, as well as to produce coating/ substrate systems with high anticorrosive performance
A displacement of the absorption maxima related to Cu (II) ion from 810 nm to 735 nm can be observed in the spectrum recorded using the solution containing tartrate (B)
Summary
Cu-Co alloy coatings can be deposited on a substrate surface to produce functional coating/substrate systems presenting enhanced properties. Cu-Co alloy coatings with high cobalt content and produced on other substrates can find suitable applications, mainly for catalytic purposes[4,6,7,8] and for anticorrosive coatings[7,8,9,10,11,12,13,14,15]. The production of these coatings by electrodeposition can be an interesting alternative to decrease the deposition process costs. The use of less toxic electrolytes may decrease the costs of the electroplating industries, which are directly related to the treatment of effluents and to the use of reinforced exhaust equipments
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