Evaluations of Hot Corrosion Behavior of Al2O3 Thermal Spray Coatings with ZrO2 Reinforcements on T-91 Steel

Different coating with varying quantities of Al2O3 and ZrO2 were fabricated on the SA213 T-91 steel using plasma spray method to study hot corrosion resistance behavior. Experiment was conducted under the molten salt environment of 60% Na2SO4-40%V2O5 at a temperature of 900℃ inside a furnace for 50 cycles. Each cycle consisted of 1hr heating and 20 min cooling at room temperature. Results were examined using the visual inspection, weight change measurement, X-ray diffraction technique and Scanning Electron Microscopy/ Energy Dispersive X-Ray Spectroscopy (SEM/ EDS) analysis. Results showed that uncoated T-91 steel was more prone to hot corrosion as compared to coated steel specimens. It was noticed that ZrO2 reinforcements in Al2O3 coating matrix helped to enhance corrosion resistance of these coatings. The corrosion resistance increased with increase in ZrO2 content in coating matrix.