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

Abstract

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.