OPTICALLY SELECTIVE STRUCTURES BASED ON NANOSCALE CHROMIUM CONDENSATES FOR PHOTOTERMAL ENERGY CONVERTERS

Abstract

The results of the formation of optically selective structures with an optical selectivity ratio of up to 11.4 are presented. These structures are based on nanoscale two-phase chromium–chromium oxide condensates developed via vacuum deposition on copper substrates. A comprehensive experimental study was conducted to evaluate the composition, structure and selective optical parameters (integral, absorptance, thermal emittance, and selectivity ratio) of the test samples. The analysis of the influence of deposition process parameters for nanoscale chromium layers and substrate surface roughness on the properties of optically selective structures is provided. It was established that increasing the substrate roughness contributes to an increase in the integral emittance of the selective structures up to 0.32, which consequently reduced the optical selectivity ratio to 2.8. The results of the investigation into the stability of the selective optical parameters under elevated temperatures and ultraviolet radiation allow for the recommendation of these structures for application in photothermal converters at temperatures up to 500 K under vacuum conditions (1 Pa).