Preparation and Thermophysical Properties of CeO2-Gd2O3 Costabilized Zirconia Thermal Barrier Coating

Solution precursor plasma spray is a novel coating deposition method in which an aqueous chemical precursor feedstock is injected into a plasma torch to deposit coatings. In this study, a 16 mol.% CeO2-4 mol.% Gd2O3 (16Ce-4Gd)-costabilized ZrO2 (CGZ) thermal barrier coating was deposited by using the solution precursor plasma spray. The crystallization process and pyrolysis products of the CGZ solution precursor powder were evaluated by synchronous thermal analysis coupled with Fourier transform infrared spectroscopy and quadrupole mass spectrometry. The phase composition and stability were characterized by x-ray diffraction and Raman spectra. The crystallization and decomposition of ZrO2 in the precursor powder mainly occurred below 600 degrees C. The CGZ coating showed good phase stability, and no m-ZrO2 was detected in the as-sprayed coating and after 200 h of heat treatment at 1400 degrees C. The thermal conductivity of the CGZ coating was ~ 0.82 to 0.96 W m(-1) k(-1), which is at least 50% lower than that of the 8YSZ coating. The thermal expansion coefficients of the CGZ coating were higher and more stable than those of the 8YSZ coating for all temperature ranges. The thermal cycling lifetime of the CGZ coating was ~ 620 cycles in a 1-h furnace cycling test at 1121 degrees C.