Corrosion behaviour of detonation gun sprayed cermet coatings on AA5083

Cermet coatings were fabricated on AA5083 by D gun coating technique using three different combinations of powder feedstock namely WC-Co, WC-Co-Cr, and Cr3C2-NiCr. The effect of powder combinations on coatings' phase composition, surface morphology, and cross-sectional microstructure were investigated using XRD, SEM, and EDS. Major findings revealed that WC-Co and WC-Co-Cr powders produced higher thickness with considerable surface defects compared to a coating that was produced by Cr3C2-NiCr powders. Moreover, a smooth compact and a uniform coating was obtained by using Cr3C2-NiCr powders. Electrochemical corrosion results showed that the OCP values of all the coated samples were shifted to a higher value than substrate and sample coated with Cr3C2-NiCr powder showed a stable OCP and more positive value than other coated samples. Similarly, the PDP curve of sample coated with Cr3C2-NiCr also showed lower corrosion current density at the cathodic region and better passivation behaviour in the anodic region.