Effects of Pretreatment on the Structure and Properties of Electroless Nickel Coatings

m e pretreatment process can significantly affect the corrosion resistance of Electroless Nickel (EN) coatings. One of the most important reasons is that different pretreatment processes can give different surface morphologies of the substrate. The Sanning Electronic Microscope (SEM) and the Scanning Tunneling Microscope (STM) have been used to investigate the structure and properties of EN coatings in the as-plated condition for various deposition times in relation to different mechanicallchemical pretreatment processes. Morphology of the substrate surface is found to be a key factor in the control of the porosily of EN coatings. it can significantly affect the formation of EN deposits not only in the early stage but also the morphologylstructure during the continued growth of the EN deposit. Possible porosity is associated with the morphology of the substrate and the coalesce of the nodules in the EN plating.