Deposition of Al₂O₃ ceramic film on copper‐based heterostructured coatings by aluminizing process: Study of the electrochemical responses and corrosion mechanism of the coating

Abstract

The effect of deposition of the Al2O3 ceramic film by the aluminizing method on electrochemical responses and corrosion mechanism of copper‐based heterostructured coatings was studied. The single layer coatings of Cu and Al2O3 and Cu/Al2O3 double layers were produced using reverse pulsed current electroplating process followed by powder cementation of aluminum on a substrate made of Inconel 600 superalloy. The produced coatings were then characterized using Scanning Electron Microscope (SEM), Energy Dispersive Spectroscopy (EDS), and X‐ray Diffraction (XRD) methods. In order to evaluate the behavior and corrosion mechanism of the produced coatings, potentiodynamic polarization and electrochemical impedance spectroscopy methods were also used in 1 mol/L HCl solution at immersion times of 1, 12, 24, and 48 hours. The results of the study showed that the mechanism of the formation of Cu/Al2O3 copper‐based coatings is that in the aluminizing step, first, the diffusion of Al from the surface layers to the interior occurs and then the diffusion of Cu from the plating layer to the exterior takes places. It was also found that the deposition of the Al2O3 ceramic film resulted in the formation of α‐Al2O3 and CuAl2O4 phases and increased corrosion resistance in Cu/Al2O3 copper‐based coatings at all immersion times and the corrosion mechanism has changed from uniform to localized state.

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