Abstract
Copper-rich Cu-Zn alloy coatings were successfully codeposited on steel substrates using glutamate-based electrolytes at room temperature. The effect of various proportions of Cu
2+
and Zn
2+
ions in the electrolyte on the current efficiency and on the metal content in deposited alloy was studied. It was found that the current efficiency was 53-99%, depending on the operating conditions and the bath composition, which could be considered high, in comparison with those of cyanide (75%) and citrate baths (70-80%). On the other hand, the Cu content in the deposit ranged from 20% to 98%. The electrochemical kinetic data confirm that addition of monosodium glutamate (MSG) to the plating bath increases i
o
and decreases the Tafel slope while the transfer coefficient is invariant. The relative invariance of α
c
, observed for increasing glutamate ion concentrations, suggests that the Cu-Zn alloy electrodeposition pathway is not affected by the presence of glutamate. The data of throwing power, throwing index and Wagner number are consistent with each other.