Revealing Microstructure and Electrochemical Corrosion Behaviour of CoNiCrAlY Coatings Fabricated by Supersonic Plasma Spraying

Abstract

CoNiCrAlY coatings are commonly employed in high-temperature oxidizing and corrosive environments because of their exceptional properties. The present study places emphases on the microstructural evaluation and corrosion behaviour of CoNiCrAlY coatings fabricated onto Inconel-718 nickel-based superalloy substrate by supersonic plasma spraying (SSPS) technique. The microstructure, phase composition and corrosion behaviour of the coating in 3.5% NaCl solution were investigated. According to the results, the SSPS coating revealed a lamellar structure with dispersed oxides in the gamma-matrix, which resulted in higher hardness compared with Inconel-718 substrate. Electrochemical studies demonstrate that the supersonic plasma-sprayed CoNiCrAlY coatings display better corrosion resistance than Inconel-718 substrate.