Development of SiO2 based thin film on metal foils for space application

Silica (SiO2) mono-layer and silica–alumina (SiO2–Al2O3) bi-layer thin films were developed on both SS304 and Ti thin foils by pulsed rf magnetron sputtering. The solar absorptance (αs) and IR emittance (εir) of the films were measured. Both αs and εir of SS304 and Ti were increased after depositing SiO2 and SiO2–Al2O3 bi-layer thin film. The ratio of solar absorptance and IR emittance (i.e. αs/εir) can be tailored in a large range e.g. 3.3–0.850 for SS and 3.66–1.085 for Ti which is useful for many spacecraft subsystems to tailor their operating temperatures. Further, the microstructure, surface morphology and topography of the films were investigated by field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and atomic force microscopy.