Corrosion Electrochemical Noise Analysis of Thermal Spraying NiAl-Based Coatings on FeCoNi Superalloy

Abstract

At present, there is little research on the corrosion resistance of the bonding coating in the abradable seal coating (ASC) systems. NiCrAl and NiAl coatings were prepared on FeCoNi superalloy by atmospheric plasma spraying (APS). The corrosion behaviors of NiCrAl and NiAl coatings in 3.5 wt.% NaCl at different immersion time were investigated by electrochemical noise (EN), scanning electron microscopy (SEM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS). Wavelet analysis results indicate that the involvement of Cr reduces the electrochemical activity of the NiAl-based coatings. The current and potential power spectral density (PSD) plots for different immersion time of the two coatings show that all k values are less than − 20 dB/decade. The results of electrochemical noise and potentiodynamic polarization curves demonstrate that the NiCrAl coating exhibits superior corrosion resistance. The changes in electrochemical noise are strongly correlated with variations in potentiodynamic polarization curves.