Investigations on vacuum-evaporated CSZ thin films for thermal barrier applications

Ceria-stabilized zirconia (CSZ) thin films have been developed over Ni-based alloy substrate by vacuum evaporation method using an electron beam. X-ray diffraction (XRD) analysis of the film heat treated at different temperatures reveals monoclinic phase stabilization. Transmission measurements of the films annealed at different temperatures, in the wavelength region 300-1,100 nm, indicate that the band gap energy of the films lies between 3.6 and 3.8 eV. Refractive index of the films was found to increase with the increase in the annealing temperature. Micro hardness of the films increases nonlinearly with the increase in annealing temperature, indicating an improvement in the hardness of the films. Thermal conductivity studies of the CSZ-coated substrate show a nonlinear decrease with the increase in annealing temperature. Surface investigations of the CSZ films confirm an increase in grain size and a decrease in surface roughness with the increase in annealing temperature of the films.