Electrodeposition of Copper on AZ91 Mg Alloy in Cyanide Solution
Journal of the Korean institute of surface engineering
Copper electrodeposition on AZ91 Mg alloy was studied in views of preferential deposition on α-or βphases and how to achieve uniform deposition over the entire surface on α-and β-phases in a cyanide solution. The inhomogeneous microstructure of AZ91 Mg alloy, particularly α-and β-phases, was found to result in non-uniform deposition of zincate layer, preferential deposition of zincate on β-phases, which leads to nonuniform growth of copper layer during the following electrodeposition process.
... position process. The preferential depositions of zincate can be attributed to higher cathodic polarizations on the β-phases. Pin-hole defects in the copper electrodeposit were observed at the center of large size β-phase particles which is ascribed to gas bubbles formed at the β-phases. The activation of AZ91 Mg alloy in hydrofluoric acid solution was used to obtain uniform growth of zincate layer on both the α-and β-phases. By choosing an optimum activation time, a uniform zincate layer was obtained on the AZ91 Mg alloy surface and thereby uniform growth of copper was obtained in a cyanide copper electroplating solution.