Evaluation of potential residual silica as antireflective layer for selective solar surface of black chromium

Abstract

Selective surfaces have the function of absorbing strongly the sunlight, while ideally losing little heat to the environment via convection and radiation. The present study sought to obtain a selective surface of black chromium coated with an antireflective (AR) layer based on sugarcane bagasse ash using copper as a substrate. From this selective surface the electrodeposition parameters (time, working distance, voltage) as well as the surface behavior were analyzed in order to determine if the AR layer provided an increase in the absorption levels of the film. By means of the present study it was possible to conclude that, in terms of the electrodeposition parameters evaluated, the anode-cathode distance of 5 cm stimulated the obtaining of higher levels of absorption. The addition of the antireflective layer on the black chromium films favored the increase of the absortance average in all the adopted parameter sets, besides reducing the standard deviation around the average. As for the microstructure of the obtained films, the increase of the parameter Ra promoted the increase of the absorption, due to the formation of optical traps.