Avaliação do potencial da ilmenita para produção de superfícies seletivas para coletores solares térmicos.

Abstract

The world is moving at a fast pace in the consumption of non-renewable natural resources, causing several ecological problems. In this context, alternative and renewable sources of energy, such as solar energy, have gained prominence, strengthening research involving the use of these forms of energy worldwide. Solar thermal conversion is one of the simplest ways to harness the sun's energy. However, there are limitations in its application, mainly related to processes that require higher temperatures. Selective surfaces are the latest and most effective alternative for thermosolar system improvement. Given this reality and aiming at regional development, a selective surface was developed in this research, based on ilmenite, abundant titanium ore in the state of Paraíba. The raw material was initially characterized by X-ray Diffractometry (XRD), X-ray Fluorescence (FRX), Transmittance Fourrier Transform Medium Infrared Spectroscopy (FTIR) and Thermal Analysis (TGA, DTA and DSC) for evaluation of the potential of ilmenite as precursor material of selective solar surfaces. Titanium ore was sieved and sintered in the pellet methodology and deposited on 304 stainless steel and aluminum substrates. The coatings produced in this research were prepared via hollow cathode deposition and optically characterized in the ultraviolet, visible and infrared bands of the electromagnetic spectrum. Microstructural evaluation of coatings by Scanning Electron Microscopy (SEM) was also performed and data on the roughness parameters of the films produced were obtained by Optical Profilometry. Thus, selective surfaces with high solar absorbance, 86%, and low thermal emission, 14%, were obtained by validating the potential of ilmenite to produce selective surfaces for thermal solar collectors.