Fabrication and properties of triplex NiCrAlY/nano Al2O3·13%TiO2/nano TiO2 coatings on a magnesium alloy by atmospheric plasma spraying method

In this study, plasma sprayed multilayered coatings were successfully applied on the Mg alloys. On the other hand, corrosion behaviors of the coated magnesium alloy substrates with three different plasma sprayed coatings consisting of NiCrAlY, NiCrAlY/nano Al2O3·13%TiO2 and NiCrAlY/nano Al2O3·13%TiO2/nano TiO2 coatings were elaborated in 3.5 wt% NaCl solution. Electrochemical studies depicted that the novel coating (NiCrAlY/nano Al2O3·13%TiO2/nano TiO2) is able to reduce the corrosion rate of the Mg alloy and increase impedance values compared to the other samples. In fact, TiO2 sealing layer could fill some micro-pores in the Al2O3-13 wt%TiO2 coating and could prevent the concentration of the electrolyte in the Al2O3-13 wt%TiO2 coating.