Effect of TiO2 on plasma sprayed Al2O3 based composite coatings at 900°C in molten salt environment

Abstract

The present work investigates the effect of hot corrosion on ASTM-SA213-T-22 Steel with different coatings of Al2O3-TiO2 at 900°C in molten salt environment (40wt%Na2SO4+60wt%V2O5). The experimentation consisted of 50 cycles of heating coated and uncoated specimens for 1 hour at 900°C in muffle furnace and cooling for 20 minutes at ambient temperature. The corroded specimens were analyzed using visual examination, weight change measurement, X-ray diffraction technique and Scanning electron microscopy/Energy-disperse X-ray analysis. The results showed that the uncoated substrate had been more affected with corrosion and gained more mass due to formation of iron oxide (Fe2O3) as compared to coated substrate because of better adhesion of Al2O3 coating with base metal SA213-T22 due to presence of TiO2. The presence of TiO2 increased the strength and durability of Al2O3 coating to withstand with high temperatures.