Electrochemical Characteristics in Seawater for Cold Thermal Spray-Coated Al–Mg Alloy Layer

Abstract

For corrosion protection of carbon steel in a marine environment, cold arc thermal spray coating was applied to the surface with Al and Al–Mg alloy wires. The surface hardness of Al and Al–Mg thermal spray coatings increased with Mg content. And the various electrochemical experiments were carried out to evaluate corrosion damage characteristics of the thermal spray coating layers. The Al and Al–Mg thermal spray coating layers presented negative potentials compared to carbon steel in corrosion potential measurements. And an anodic polarization experiment revealed a tendency of activation polarization with no passivation. Furthermore, the corrosion damage of the thermal spray coating layer in galvanostatic experiment was observed mainly at the defect area, and the Al–3Mg thermal spray coating layer presented less surface damages than others. In addition, the Al–3Mg thermal spray coating layer showed the lowest corrosion rate while having a sufficient driving voltage for cathodic corrosion protection. Therefore, it is an optimal thermal spray material for sacrificial anode.