Electron beam physical vapour deposited zirconia based ceramics for developments of solar surface coatings

Abstract

Infrared radiative properties of thermal barrier coatings have been investigated for developments of solar absorbing surface coatings. Various types of multilayer broadband optical filters were designed incorporating 7 wt-% yttria stabilised zirconia (7YSZ) and aluminium oxide (Al₂O₃). Electron beam physical vapour deposition method was employed to deposit 7YSZ thin films on quartz substrates to study their optical properties. The refractive index and thickness of 7YSZ films were estimated using spectroscopic ellipsometry technique, giving the index as 1·95 at 633 nm. Multilayer thermal barrier coating structures were fabricated by depositing alternate layers of 7YSZ and Al₂O₃ on quartz using electron beam physical vapour deposition. The spectral characteristics of multilayer 7YSZ–Al₂O₃ coatings were evaluated using a spectrometer in the visible and near infrared range. Preliminary results obtained from multilayer 7YSZ–Al₂O₃ coatings had exhibited 75% transmission over a wide band of 0·4–1·0 μm.