Obtaining calcium ferrites doped with chromium aims application in transparent and matte glazes

摘要

This work aims to obtain oxides with a spinel type structure of composition CaFe1,8Cr0,2O4 by the gelatin method, aiming application in transparent and matte glazes glazes. The precursor powders, resulting from the synthesis process, were calcined at 600 ?° C and 800 ?° C to obtain the spinel phase. The powders were characterized by infrared spectroscopy, X-ray diffraction, followed by Rietveld refinement, diffuse UV-visible reflectance spectroscopy and CIE-L*a*b* colorimetry. The powders were then incorporated into the bright and matte transparent glazes in the proportion of 2% by weight, coated ceramic substrates and then sintered at 1100 ?°C. According to the X-ray diffractograms, the powders had an orthorhombic spinel structure. The calcium ferrites doped with chromium presented orange coloration, being darker in the calcined powders at higher temperatures. The glaze coating results showed that there was compatibility between pigment and glaze brigth. We already mate glaze, there was abrupt variation of color. The hydrochloric acid attack showed that the prepared glazes are highly resistant to chemical attack. Finally, this work concludes that the gelatin route was efficient in synthesizing oxides with a single-phase spinel structure at low synthesis temperatures and that the obtained pigments are viable for industrial application.