The acidic hypophosphite-based electroless nickel bath has yielded coatings having 10 to 11 of phosphorus. X-ray diffraction studies reveal that the as-deposited coating is amorphous in nature and upon heat treatment above 350℃ it becomescrystalline as a result of the formation of nickel phosphide and fcc nickel. The DSC plot ascertains the temperature (348℃) at which the conversion from an amorphous to crystalline phase occurs. The TEM study exhibits the amorphous nature of theas-deposited coatings. The corrosion current density of the coating in 3.5 sodium chloride solution is of the order of a few microamperes. The wear resistance is found to be higher for coatings heat treated at 400℃ for 1 hour than that of theas-deposited coatings. The preliminary studies made on the stability of the bath with the addition of various second-phase particles reveal that the bath is stable for at least 4 to 5 hours; hence, it can be concluded that the present bath is a suitablecandidate for producing electroless nickel as well as electroless nickel composite coatings.
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