Electrodeposition of Cobalt Rich Zn-Co alloy Coatings from Citrate Bath

• Autor(a) principal: Garcia,Julyana Ribeiro
• Data de Publicação: 2014
• Outros Autores: Lago,Dalva Cristina Baptista do, Senna,Lilian Ferreira de
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Materials research (São Carlos. Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S1516-14392014000400019
• topic: Electrodeposition; Zn-Co alloy coatings; sodium citrate; corrosion protection

Zn-Co alloy coatings were produced on carbon steel, at room temperature, from citrate baths (0.100 mol L-1) containing [Zn2+]= [Co2+] = 0.05 mol L-1. Coatings with %m/m Co &gt; %m/m Zn were observed under all deposition conditions, except for I = 10 A m-2. As the current density (I) was increased, a significant decrease (p<0.05) in %m/m Zn was noted, and the highest value of % m/m Co was observed at 80 A m-2. The Co-rich coatings presented refined microstructure, with small grain sizes. The smallest Icorr of the studied substrate/coatings systems, 2.4 µA cm-2, was obtained at I = 10 A m-2. Under these conditions, the coatings contained ~ 30 % m/m Co and 70 % m/m Zn and only the γ-ZnCo phase was obtained. The Icorr found in the present work is smaller than those usually found in the literature for Zn-Co coatings with small Co content.