Cobalt-based pigments for application in ceramic coatings

Abstract

Inorganic pigments were prepared with spinel structure for applications in ceramic tiles. Pigments with composition CoCr₂O₄ and Co_0.8Zn_0.2Cr₂O₄ were synthesized by a chemical route using gelatin for pharmaceutical use as an organic precursor. The influences of doping and thermal treatment temperature on pigment and ceramic glaze color were investigated. The materials were characterized by thermogravimetric analysis, X-ray diffraction, scanning electron microscopy, dispersive energy spectroscopy, spectroscopy in the UV-visible region and colorimetry. The powders treated at 500 °C presented spinel structure, with the formation of residual secondary phase of Cr₂O₃ in samples Co_0.8Zn_0.2Cr₂O₄ heat-treated at 500 and 1000 °C. The prepared pigments and glazes presented blue-green colors for the samples CoCr₂O₄ and green color for the sample Co_0.8Zn_0.2Cr₂O₄. The results confirmed the effectiveness of the synthesis route used to produce oxides with a spinel structure.

Keywords:
synthesis of spinel; ceramic pigments; gelatin