Effect of textures on the corrosion resistance of nanocrystalline Ni coatings

Nanocrystalline Ni coatings with (111), (200) and (220) textures were respectively pulse-electrodeposited on brass. Scanning electron microscopy (SEM) was used to observe their microstructures, X-ray diffraction (XRD) analy-sis was adopted to identify the texture degree, and the anodic polarization curves and electrochemical impedance spectra were tested to investigate the corrosion resistance of the pulse-electrodeposited Ni coatings in 3.5% NaCl solution. An obvious difference in corrosion resistance exists among the coatings with different textures. The coating with (220) texture exhibits the worst corrosion resistance, with the corrosion current density of about 1.23μA·cm^-2 and the coating polarization resistance of 2.09 kΩ·cm²; the coating with (200) texture has the best corrosion resistance, with the corro-sion current density of about 0.15μA·cm^-2 and the coating polarization resistance of about 27.32 kΩ·cm²; the coating with (111) texture shows a corrosion resistance in between. The difference of surface island microstructures incurred by growth textures might be the reason for the different corrosion resistances of the as-deposited Ni coatings.