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.