Utilização do resíduo de rochas ornamentais graníticas com a adição de outros materiais para aplicação em superfície seletiva

Abstract

Electricity consumption in Brazil is greater than its generation capacity in some periods of the year, the main generation is hydroelectric in periods of drought it does not fully meet demand, which made the Federal Government build several thermoelectric plants and encourage contributions other alternative sources of solar and wind energy. One of the alternatives for reducing electrical energy consumption is the use of solar thermal energy to heat water in solar collectors, reducing electrical energy consumption with heaters and electric showers. This research evaluated the potential for using of the ornamental rocks residue (RRO) with the addition of other materials, forming new composites for application on selective solar collector surfaces; the influence of coatings applied to the AISI 304 stainless steel substrate; the effect of heat treatment on the morphology, microstructure and absorption of the produced surfaces. The fundamentals of solar radiation, structure and functioning of solar collectors, types of materials applied to substrates, studies on granite, aspects of physics and mathematics applied to power and heat, solar collector efficiency and light refraction are presented. The exception was collected at the ornamental stone processing company, mixed with other elements totaling five samples and the substrates were prepared in the laboratories of the UFPB Technology Center, where the characterization of the powders and films applied by deposition using the screen printing method was carried out, particle size tests, X-ray diffraction, infrared spectrometry - FTIR, DSC and TGA thermal analyses, UV-Vis, profilometry and microhardness tests were carried out. XRD analyzes showed that the residue is, in the majority, granitic rocks considering the phases observed. In all the analyzes carried out, the sample composed of RRO, CuO, SiC and professional araldite adhesive presented the best performance. SEM images of the surface show the microstructure with high densification, alveoli, cleavage microcracks and low roughness. The results obtained in the UV-Vis, near ultraviolet and near-infrared spectra without prejudice to the other aspects analyzed showed that among the films without heat treatment, the film (Fc) performed better, as it presented an average absorptance of 88.4% and maximum 95.2%; however, after heat treatment, the film (Fb) showed better performance, with an average absorptance of 90.5% and a maximum of 94.9%. The research carried out confirms that the materials are viable for obtaining new products aimed at application on selective surfaces for converting solar energy into thermal energy, concluding that among the materials researched, film (Fb) after heat treatment is the most suitable for application on selective solar collector surfaces, performance can still be improved with future scientific research.