Comparison of electrochemical properties of atmospheric pressure plasma coatings for Al2O3-3TiO2 and CoNiCrAlY in sea water

To improve the durability of underwater rotating products, the corrosion characteristics in harsh marine environment were evaluated through various electrochemical experiments on the Al2O3-3TiO2 and CoNiCrAlY coating layers by atmospheric pressure plasma spray coating process. By evaluating the corrosion resistance of these materials, their applicability to environmentally friendly power generation equipment such as blades of tidal current turbines was examined. According to the Tafel analysis for micro-areas including the coating layer, the coating/metal interlayer and the base metal, the Al2O3-3TiO2 coating layer and the CoNiCrAlY coating layer show markedly lower corrosion current density than the base metal. The corrosion current density of the CoNiCrAlY coating layer (9.75316×10−8 A/cm2) is about 1.6 times more than that of the Al2O3-3TiO2 coating layer (6.13139×10−8 A/cm2).