Effects of Selective Laser Modification and Al Deposition on the Hot Corrosion Resistance of Ceria and Yttria-Stabilized Zirconia Thermal Barrier Coatings

Abstract

The air-plasma-sprayed ceria and yttria-stabilized zirconia (CYSZ) coating was modified by selective laser remelting and Al deposition to enhance hot corrosion resistance. The dotted coating was obtained after selective laser remelting. Magnetron sputtering was used to deposit an Al film on the dotted coating, and a vacuum heat treatment was subsequently performed to produce a dense α-Al2O3 overlay. Hot corrosion behavior of the following three types of coatings was investigated: plasma-sprayed, dotted, and dotted coatings combined with Al deposition (DA). Hot corrosion behaviors were evaluated in a mixture of 55 wt % V2O5 and 45 wt % Na2SO4 molten salts at 1000 °C for 30 h. The hot corrosion reaction between molten salts and zirconia stabilizers (Y2O3 and CeO2) led to the generation of monoclinic zirconia, YVO4, and CeVO4 plate-shaped crystals, and the mineralization of CeO2. The results indicated that the hot corrosion resistance of the DA coating was the best, and the dotted coating had superior hot corrosion resistance in comparison with the plasma-sprayed coating. The minimal surface roughness and dense dotted units improved the hot corrosion resistance of the dotted coating. The dense α-Al2O3 overlay with chemical inertness effectively inhibited the infiltration of molten salts, which led to the optimal hot corrosion resistance of the DA coating.