A noncyanide alkaline bath for Zinc-Nickel alloy deposition

Zinc-nickel alloy has been proven as a highly corrosion resistant coating meant especially for automotive applications. The acid baths have the drawback of poor throwing power and high composition dispersion. On complicated structures, this property not only results in variation in appearance but also, ends up with setting up of local cells within the deposit itself due to variation in composition leading to lower service life than expected. So, these baths are mainly preferred for plating uncomplicated structures. The alkaline baths on the other hand, obviate the above problems, yielding deposits with uniform appearance and composition throughout the component. Due to the environmental and operational hazards posed by the conventional cyanide baths, non-cyanide baths are highly recommended and are in commercial practice abroad. This paper deals with our experience with a non-cyanide alkaline bath for depositing smooth deposits. Special addition agent has also been identified to function as a brightener. The effect of parametric variables on the composition, current efficiency and throWing power of the deposits are dealt with