Effect of coating degradation on the hot corrosion behavior of yttria-stabilized zirconia (YSZ) and blast furnace slag (BFS) coatings

Abstract

In order to provide thermal insulation thermal barrier coatings (TBCs) used in gas turbine engine components under conditions of impure fuels and high turbine inlet temperatures are expected to have hot corrosion resistance. Techniques and material combinations used in the production of TBCs are primarily effective in the progression of failure mechanisms as a result of hot corrosion. In this study, the hot corrosion damage mechanism, which is caused by the impurities of the fuels used in the industry and causes great damage to the TBC systems, was simulated and evaluated in the laboratory environment. For the creation of TBC systems, CoNiCrAlY metallic bond coating powders were deposited on Ni-based super alloy substrates by the detonation gun (D-gun) process. Commercial yttria-stabilized zirconia (YSZ) and blast furnace slag (BFS) powders were deposited on the bond coating by Atmospheric plasma spraying (APS) technique. Hot corrosion testing of TBCs was performed at 800 °C for 8, 24, 50, and 75 h in an environmental condition consisting of a 45 wt% Na2SO4 and 55 wt% V2O5 corrosive salt mixture. Blast furnace slag, which is completely cost-free and a waste product, provided excellent protection against hot corrosion damage without deteriorating its stability at high temperatures. In this way, it is open to be evaluated as a new type of coating material alternative to the traditional top coating material YSZ, which has a very high production and cost, and to be used in different areas.