The effect of metallic bonding layer on the corrosion behavior of plasma sprayed Al2O3 ceramic coatings in simulated seawater

Al2O3 ceramic coatings with different metallic bonding layers, i.e. Ni60, NiAl and FeAl, were prepared by the plasma spraying technique. To study the effect of bonding layer on corrosion behavior of plasma sprayed Al2O3 coatings, metallic coatings were also prepared for direct use as working layer. Phase analyses of the coatings were determined by X-ray diffraction (XRD). The corrosion behavior of the coated samples was evaluated by potentiodynamic polarization tests in simulated seawater. The results showed that Ni60 could make Al2O3 coating attain the best corrosion resistance amongst the three metallic bonding layers. The corrosion resistance of Al2O3 coatings first increased and then decreased with the increased Ni60 bonding layer thickness. Conclusively, it is found that chemical composition and thickness of bonding layers played an important role in the corrosion behavior of the plasma sprayed Al2O3 coatings.