Experimental Investigation on the Effect of Coating Al2O3+70% NiCrBSi Cermets on Ti-31 Superalloy to Combat Hot Corrosion

Abstract

The superalloys are generally used for high-temperature applications, and since they operate in an aggressive environment, it is required to protect them with an appropriate coating to enhance the life of the superalloy material. In the present study, the superalloy Ti-31 is coated with cermets Al2O3+NiCrBSi by high-velocity oxy fuel (HVOF) spray coating technique, and hot corrosion tests were performed on both coated and uncoated samples, in presence of Na2SO4+60% V2O5 molten salt at a temperature of 700°C, and the corroded samples are characterized using SEM/EDS and XRD techniques. From the thermogravimetric studies, it is observed that total weight gain per unit area for uncoated Ti-31 is very high compared to Al2O3+NiCrBSi-coated Ti-31 and parabolic rate constant indicates that corrosion rate is decreased when substrate is coated. The current study’s findings clearly show that the coating deposition is effective in protecting the substrate from hot corrosion.