Design, fabrication and characterization of TiO2-SiO2 multilayer with tailored color glazing for thermal solar collectors

Publication date: 15 September 2017
Source:Materials & Design, Volume 130
Author(s): Iulian Pana, Catalin Vitelaru, Adrian Kiss, Nicolae Catalin Zoita, Mihaela Dinu, Mariana Braic
The paper reports on the design, fabrication, and characterization of a 7-layer SiO2-TiO2 colored coating for solar thermal façades. A combined theoretical and experimental approach was employed for designing the colored coating by using optical modeling and individual layers characterization, targeting for high solar transmittance and pronounced yellow-green reflected color. SiO2-TiO2 multilayers were deposited on glass and silicon substrates by using the reactive RF magnetron sputtering of stoichiometric oxide targets. The coatings were investigated by UV–Vis spectrophotometric methods for optical properties, surface profilometry, X ray reflectivity and SEM for the thickness of individual layers composing the multilayer and AFM for surface roughness. Hardness H, reduced modulus Er, and adhesion were determined by nanoindentation and scratch tests. The deposited colored glazing exhibited a prominent reflectivity peak of ~54% centered at 574nm, specific visible reflectance of ~45.39% and an integrated solar transmittance of about 80.3%. Its optical properties were preserved in the ambient for temperatures up to 200°C and the color was not modified for incidence angles up to 45°. H values of 7.18GPa, Er of 88.31GPa, H/Er ratio of about 0.081 and good scratch resistance up to 13mN were measured.

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