Nickel Plating on Anodized Aluminum

Abstract

Nickel platings on pure (2S) and alloyed (61S) aluminums anodized in a phosphoric acid solution were investigated, and optimum conditions for anodizing and plating were examined by determination of adhesion and covering power of nickel deposits on the anodized bases.The results were summarized as follows:(1) Nickel was satisfactorily plated on anodized 61S Al in Watts bath.(2) In case of 2S Al, no nickel deposit having 100% of covering power was obtained under ordinary conditions. The 100% of covering power could be obtained by application of a two-stepped anodizing: the formation of anodized film as the 1st step and anodic dissolution of the film at the 2nd step.(3) The electron microphotographic observation of the film formed on 2S Al by two-stepped anodizing suggested that the defects of the thin film acted as effective centers for nucleation of nickel deposits. The thickness of the film should be within the range of 0.5-1.5μm.(4) The electron microphotographic study also seemed to support the assumption proposed in the previous paper that the deposition mechanism of metals on anodized 61S Al was not applicable to anodized 2S Al.