Development of Solar Selective Absorber Coatings by Wet Chemical Process on Different Substrates
Solar selective absorber coating by wet chemical method has been developed on commercially available stainless steel substrates of SS202 and SS316 by tandem layer approach for thelow to medium temperature application of concentrated solar thermal (CST) technologies. The base absorber layer developed by chemical oxidation and an optical enhancement layer by sol-gel method, results the coating more selective in nature. The high spectral absorptance of 94.9% and emittance of 0.14 obtained by the tandem absorber coating Cr-Fe-Mn oxide/ ZrO2 – SiO2 developed on SS202, whereas absorptance of 93.7% and emittance of 0.10 obtained on S316 tandem absorber coating of Cr-Fe-Ni oxide/ZrO2 – SiO2. Optical and structural characteristics of the coatings are characterized by UV-vis-NIR Spectrophotometer, handheld reflectometre, Fourier Transform –IR spectrophotometer, Field Emission Scanning Electron Microscopy (FE-SEM) and X-ray Photoelectron Spectroscopy (XPS). Moreover, the coatings were also studied for thermal stability and corrosion resistance property for the application of solar receiver tube in CST technology.
Keywords - Tandem absorber, Chemical oxidation, Sol-gel, Thermal stability.