Abstract
An attempt was made to electroplate a uniform and defect-free Ni-Al dispersion coating which is rich in Al particle content. Since bare Al particles without surface treatment quickly dissolved into a Watts Ni bath and yielded cracked deposits, the particles were surface-treated with one of silane coupling with γ-aminopropyltrietoxy silane (γ-APS), boiling in distilled water for 20min., or electroless plating with a Ni-B alloy. Although these treatments strongly suppressed the dissolution of Al into the bath, baths containing the silane-coupled Al particles still yielded a cracked deposit. Deposits that were crack-free and uniform in Al particle distribution were obtained from baths containing the boiled Al particles or the Ni-B plated Al particles, the surfaces of which were composed of Al (OH)3 or Ni (OH)2, respectively. Among many plating variables, diluting the watts Ni bath and decreasing the stroke of the pumping plate were found to be quite effective in increasing the Al particle content of the coating.
