Properties of nickel – tin coatings deposited from aqueous and non-aqueous electrolytes

Abstract

The compositions of aqueous chloride-fluoride and ethylene glycol citrate electrolytes and conditions for electrochemical deposition of Ni – Sn coatings, providing the production of an alloy based on Ni3Sn2 intermetallic with nickel content of 36– 40 wt. %, have been proposed. The effect of sodium and ammonium fluorides additives, as well as non-ionic surfactant OS-20 in an aqueous electrolyte or hydrochloric and citric acids in ethylene glycol electrolyte on the internal stresses and corrosion resistance of coatings has been determined. The lowest internal stresses and the highest corrosion resistance have been found to be characteristic of coatings with a fine-grained dense structure that does not change with increasing of thickness (within 1–10 μm), which include a Ni3Sn2 single crystalline phase with minimal deviations from stoichiometry. To the greatest extent, these characteristics are provided during the deposition of coatings from ethylene glycol citrate electrolyte.