Corrosion behavior of amorphous-nanocrystalline Fe-Ni-Cr electrodeposited coatings

This study deals with the fabrication and characterization of electrodeposited amorphous-nanocrystalline Fe-Ni-Cr coatings. For this purpose, electrodeposition process was done at different current densities in the range of 10-40 A/dm2. To achieve the desired microstructure, the as-deposited coatings were annealed at 250 °C for different periods of time. The prepared samples were characterized using X-ray diffraction (XRD) and field emission scanning electron microscopy (FE-SEM). Corrosion behaviors of coatings were also examined in NaCl 3.5% electrolyte by potentiostat analysis. Fully amorphous Fe-Ni-Cr coatings were successfully formed during electrodeposition process at current densities beyond 30 A/dm2. The prepared amorphous-nanocrystalline coatings exhibited good corrosion resistance with the corrosion potential and corrosion current density in the range of 375-635 mV and 0.15-5.2 μA/cm2, respectively. By annealing the produced fully amorphous coating, Fe-α and FeNi phases precipitated from the amorphous matrix. The precipitation of these phases had deleterious effects on corrosion resistance of as-deposited coatings.