Synergistic Effect of Cavitation-Erosion and Corrosion of Al and Al-Mg Alloy Coatings by Arc Thermal Spraying in Sea Water

When the arc thermal spray coating layer for corrosion protection designed to extend the life of steel is exposed to an actual marine environment, physical damages by external forces and corrosion damages occur simultaneously in combination. In this study, various electrochemical tests were conducted after thermal spray coating using Al, Al-3Mg, and Al-5Mg thermal spray wires on carbon steel in a cavitation environment to evaluate the multiple damage behaviors. As a result, the breakdown of the passivation film by the cavitation impact pressure and corrosion damage by Cl- ions occurred in combination, which increased the corrosion current density of the thermal spray coating layer. Furthermore, the Al-3Mg thermal spray coating layer presented the best corrosion resistance and cavitation resistance.