Structure and Corrosion Resistance of Nickel–Molybdenum Alloy Coatings

Abstract

Electrolytic Ni–Mo alloy coatings were obtained from the galvanic bath, at the temperature of T = 60 C under galvanostatic conditions using a cathodic current density of j = 80 mA cm􀀀2. Surface morphology was studied using a scanning electron microscopy. Chemical composition of obtained coatings was determined by the energy dispersive spectroscopy. Structural studies were carried out using an X-ray diffraction method. Electrochemical corrosion resistance tests were carried out in 5% NaCl solution. It was found that X-ray diffraction investigations of all obtained coatings showed the characteristic “halo”, which suggests that the obtained deposits have an amorphous structure. Chemical composition and corrosion resistance of the electrolytic Ni–Mo coatings depend on the concentration of Na2MoO4 2H2O in a galvanic bath. With the increase of the molybdenum content in the alloy coatings, their corrosion resistance increases.