Effect of Different V2O5 Salt Concentrations in Presence of Chloride and Sulfate Salt on Hot Corrosion Behavior of Functionally Graded Lanthanum Zirconate Thermal Barrier Coating

In the present study, the multilayer functionally graded (FG) thermal barrier coating consisting of bond coat (NiCoCrAlY) and lanthanum zirconate (La2Zr2O7) was designed. The developed coating was evaluated for the effect of Na2SO4, NaCl, and V2O5 salts on hot corrosion at the temperature of 900degree celsius. Under the study, each salt is used, then in a combination of all three with increasing concentration of V2O5 from 0 to 25% keeping NaCl concentration constant to 5% and adjusting the concentration of Na2SO4 salt to make the total concentration of combined salt equal to 100%. The highest corrosion among the salt combinations resulted due to Na2SO4, NaCl, and V2O5 in the wt % ratio of 75 : 5 : 20. The SEM, EDS, and XRD studies revealed the presence of LaVO4 plates, and monoclinic ZrO2 resulting in the failure of coating. The present study also revealed the oxides formed due to corrosion and their effect on the coating.