Fabricação de vidros boro sódico-cálcicos transparentes utilizando sílica proveniente da casca de arroz

Abstract

The use of alternative materials in the manufacture of industrial products has been the focus of research in several areas. In this sense, this work aims to use rice husk ash, considered a material with high silica content, for the production of transparent boronsodium-calcium glasses in the visible region of the electromagnetic spectrum. For this purpose, the rice husk was first calcined at a temperature of 800 °C for 5 hours; the resulting ash was evaluated by X-ray Fluorescence measurements, and 93% silica was determined. On the other hand, the ash contains metal ions in its composition, especially iron and manganese ions, which are elements known to give color to the glass. To reduce the color effect due to these elements, antimony oxide was used in the composition of glass since this oxide can reduce Mn3+ to Mn2+. Thus, the glasses were produced from mixtures of SiO2, Na2O, CaO, B2O3,Sb2O3 considering the addition of different mass concentrations of antimony oxide: 0.00;0.03; 0.50 and 2.00 mol%. For comparison, a reference sample was manufactured containing silica from sand and 0.00% of antimony oxide in the composition. Glass transparency was evaluated and compared with the reference sample by spectroscopy measurements in the Uv-Vis region. Solarization measurements were performed in the samples manufactured in order to evaluate whether the transparency was permanent or not. In addition, fluorescence measurements in antimony samples revealed the presence of Mn2+ ions, which allowed to justify the color change of the produced glasses. As a complement, measurements of densities of the manufactured glasses were performed in order to verify whether they could be applied in the manufacture of retroreflective microspheres considering the parameters given by the NBR 16184 standard (ABNT, 2013).