Nanostructured Gd2Zr2O7: a promising thermal barrier coating with high resistance to CaO–MgO–Al2O3–SiO2 corrosion

Nanostructured Gd2Zr2O7(NGZO) thermal barrier coatings (TBCs) have great potential applications in airplane engines and hot sections of gas turbine engines operating in volcanic ash-exposed or dust-laden environments. In this paper, NGZO is deposited on IN738LC/CoNiCrAlY using the atmospheric plasma spraying (APS) technique. Also, yttria-stabilized zirconia (YSZ) was utilized to produce conventional TBC. The CaO–MgO–Al2O3–SiO2 (CMAS) corrosion resistance and phase stability of IN738LC/CoNiCrAlY/YSZ (YSZ: ZrO2 4 mol.% Y2O3 as the conventional TBCs) and IN738LC/CoNiCrAlY/NGZO (NGZO: ZrO2 33 mol.% Gd2O3 as the new generation of TBCs) were assessed at 1250 ˚C by 5-h cycles with and without the presence of CMAS particles. The X-ray diffraction (XRD) analysis and microstructural investigations by field emission scanning electron microscopy (FESEM) equipped with an energy-dispersive X-ray spectroscope (EDS) revealed that NGZO coatings had high resistance against penetration of CMAS particles by forming an accelerate non-permeable Gd8Ca2(SiO4)6. Also, the qualitative and quantitative XRD analyses by the Rietveld refinement method indicated that the NGZO coating maintained its phase stability during the thermal cycles after 20 h of exposure to 1250 °C.