Copper Binary and Ternary Alloys as Anticorrosive Coatings for Carbon Steel in a Saline Medium

This work compares the anticorrosive properties of DC electrodeposited CuCoNi, CuCo, and CuNi alloy coatings in a NaCl 0.5 mol L-1 solution. The results showed that j and the bath composition influenced the chemical, morphological, and electrochemical characteristics of the alloy coatings. Among all the studied coatings, the CuCo, CuNi, and CuCoNi ones produced at j = 10 A m-2, j = 60 A m-2, and j = 25 A m-2, respectively, showed the best anticorrosive performances in the saline medium, exhibiting charge transfer resistances (Rtc) higher than 2000 & omega; cm2 and an electrical double layer capacitances (Cdl) lower than 8 X10-4 F cm-2. These results agree with the compact morphologies and smaller grain sizes presented by these coatings. Therefore, the anticorrosive properties of the coatings cannot be related only to the less noble metal(s) contents in the alloy but also to their morphologies.