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

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.