Influence of Thermal Treatment on the Structure and the Corrosion Resistance of Zn-Ni Alloy Coatings

摘要

Electrolytic Zn-Ni alloy coatings were obtained on the steel substrate under galvanostatic conditions, and then, subjected to thermal treatment in argon atmosphere. The influence of thermal treatment on the surface morphology, phase composition and corrosion resistance of the electrodeposited coatings has been studied. Surface morphology was examined using a scanning electron microscopy. Chemical composition was determined by a X-ray fluorescence spectroscopy. Structural studies were carried out using a X-ray diffraction method. Corrosion resistance tests were carried out in 3% NaCl solution using open circuit potential method and potentiodynamic measurements. It was found that after thermal treatment, the value of polarization resistance increases, the value of the corrosion current decreases, and the value of corrosion potential is shifted towards anodic potentials. This suggests a positive effect of thermal treatment of the Zn-Ni alloy coatings on their corrosion resistance.