Controlled deposition, electrical and electrochemical properties of electroless nickel layers on microarc oxidized magnesium substrates

Abstract: We prepared various porous structures on magnesium substrates by microarc oxidation (MAO) pretreatment in different solutions, and then controllably deposited electroless nickel (EN) layers on them under identical plating conditions. The results indicate that the microstructures, electrical and electrochemical properties of EN layers are highly dependent on the porous surface. Thin layer including tiny nickel granule is deposited on NaF-solution-pretreated substrates, but thick layer, consisting of typical nickel nodule, is formed on substrates oxidized in Na2SiO3 solution, while excellent electrical conductivity and corrosion resistance are obtained. Whereas, the reticular-structured layers with wormlike nickel as well as high thickness and resistivity are area-selectively deposited on the substrate pretreated in Na3PO4 solution. [Copyright &y& Elsevier]