A High Effective Selective Absorbing Coating for Solar Thermal Collectors

Abstract

High effective selective absorbing bimetallic structures of Sn and Ni for solar thermal collectors have been investigated. They were produced by cathode electrodeposition on polished copper plates from water solution. Scanning electron microscopy micrographs show that they consist of a highly branching layer of bimetallic needles. They serve as a radiation trap for the solar radiation because of multiple reflections. The reflectance spectra were measured in the visible and infrared range. The absorptance of the coating was calculated as 98% in the solar radiation range and the thermal emittance in the infrared region at 100 °C - as 10%. The selective absorbing coatings are investigated by X-ray diffraction analysis and X-ray photoеlectron spectroscopy as well as optical spectra in the UV-VIS and IR region. The samples with selective absorbing coatings have been tested at natural solar radiation. The results show that the new coatings have substantial advantages in comparison to the widely used black chrome.