K D. Harris, D Vick, E J. Gonzalez, T Smy, K Robbie, M J. Brett
A new approach is described in the deposition of thin films for thermal barrier applications. In a physical vapour deposition experiment, extreme shadowing, present only at highly oblique flux/substrate angles, was employed to introduce porosity into thin films of zirconia. Using controlled substrate motion, solid capping layers were added. By depositing porous layers and capping layers in an alternating fashion, a new, porous, multilayered structure was fabricated for evaluation as an improved thermal barrier coating. Direct measurement, by the Mirage and 3ω techniques, of thermal properties within these films led to the estimate of a thermal diffusivity approximately 9% that of films deposited entirely at normal incidence. Thermal simulations of similar structures also predicted a substantial decrease in overall thermal conductivity. In a specific case, the conductivity was estimated to be 18% of films deposited by standard techniques.
Surface and Coatings Technology
film microstructure, therm conductivity, thermal barrier coatings, zirconia