Electrochemical Behaviour of NiCrBSi/Mo Air Plasma Sprayed Composite Coatings in Chloride Containing Solutions

NiCrBSi/Mo Air Plasma Sprayed composites coatings were prepared by a codeposition of mixtures of pure Mo and NiCrBSi alloys powders. The electrochemical behaviour of the NiCrBSi/Mo composites coatings were examined in 0.5M NaCl solution using potentiodynamic and linear polarisation techniques complemented with Scanning Electron Microscopy (SEM) and Energy Dispersive X-Ray Analysis (EDXA). The effect of post spraying heat treatment for improving the corrosion resistance was also evaluated. The results showed that the protective ability of coatings is mainly determined by their porosity and Cr and Ni content. Deterioration of the corrosion resistance of the APS coatings was caused by generation of microcrevices between the lamellas. The post-spraying heat treatment played a beneficial role in improving the corrosion resistance.