Investigation of Hot Corrosion Behaviour of Ytterbium Oxide Doped Gadolinium Zirconate Thermal Barrier Coating for Gas Turbines

The hot corrosion behaviour of Yb2O3 doped gadolinium zirconate (Gd2Zr2O7, GZ) as a ceramic top coat for thermal barrier coatings (TBCs) applications is investigated in this study. The solid-state reaction approach was used to synthesize Yb2O3 doped GZ (9, 12, 15 weight percent Yb2O3). Prior to applying the ceramic top coat, the metallographically prepared Hastelloy X substrate was plasma sprayed with NiCrAlY metallic bond coat. Using the atmospheric plasma spray (APS) process, ceramic top coatings such as 9YbGZ, 12YbGZ, and 15YBGZ were deposited onto bond coated Hastelloy X substrates. To examine the hot corrosion behaviour of TBCs, molten salt mixture of Na2SO4 and V2O5 were applied to coated samples and subjected to high temperature at 1273 K for 50 h in a muffle furnace. The structural properties were investigated using the X-ray diffraction (XRD) technique. After the hot corrosion test, a high resolution—scanning electron microscopy (SEM) was utilised to evaluate the surface morphology and microstructural properties of the coatings. The hot corrosion resistance of the coatings and their performance were thoroughly reviewed.