Study of Sol-Gel Metal Oxide Deposition on Stainless Steel Substrate for Solar Energy Applications

Abstract

This thesis subjects the issue of multi-layer stacking of several materials in order to produce a successful solar selective coat. An extensive literature survey was held to summarize the previous efforts in this area. Accordingly, five metals and six oxides were chosen for investigation. A simulation software, named Openfilters, was used to simulate the reflectance behaviour of several multi-layered tandems and the effect of layers’ thickness. Best tandems in simulated reflectance were Al/CuO, Al/Si/TiO2, Al/Si/CuO, WO2/CuO/SiO2 and Ni/CuO/TiO2. Due to limitations in the production of some layers, experimental validation was held for Ni/CuO/TiO2 with an anti-reflectance layer of SiO2. Copper oxide, titanium oxide and silicon oxide were all prepared through sol-gel approach and deposited through dip-coating technique over stainless steel 304 samples. Copper oxide was studied using two different routes. One adopted changing the pH value and investigating its effect on optical properties, while the other adopted increasing the percentage of polyethylene glycol. Multi-layered stacks of SS/Ni/CuO/TiO2/SiO2 were also investigated. Stainless steel substrate was Ni electroplated before sol-gel deposition. Full film characterization through Scanning electron microscopic analysis, X-ray diffraction, energy dispersion x-ray investigation and optical properties (absorptivity, emissivity, optical bandgap and refractive index) were calculated and discussed in details.