Development of Equal Proportional YSZ + Al2O3 Thermal Barrier Coating and Effect of Coating Thickness on the Corrosion Behaviour on Cast Iron Substrate

Thermal barrier coating (TBC) degradation has been identified as a primary problem in the case of hot corrosion via Na2SO4–V2O5 deposits. In comparison with the current top coat thickness, the current research presents a novel TBC that combines equal amounts of pure alumina (Al2O3) and yttria-stabilized zirconia (YSZ) with improved resistance to heat corrosion. Using the atmospheric plasma spray (APS) process, Al2O3 and YSZ were sprayed as a bond coat on cast iron substrates using the multilayer bond coat materials Metco 410NS and Metco 452. Utilizing a cyclic method, the hot corrosion behaviour of TBC was examined at 850 °C using a corrosive salt consisting of 45 weight percent sodium sulphate (Na2SO4) and 55 weight percent vanadium pentoxide (V2O5) powders. In increments of 100 µm, the top coat thickness ranged from 100 to 300 µm. The results indicated that a 300 µm top coat thickness will result in a greater hot corrosion resistance. The disintegrate of the TBC systems is also caused by corrosive salts like Na2SO4 and V2O5, which have the ability to dissolve the stabilizers in the zirconia coating at high temperatures.