Effect of the Fe/Cr molar ratio and calcination temperature on the preparation of black ceramic pigment with stainless steel dust assisted by microwave processing

Abstract

Transition metal elements rich in stainless steel dust (SSD), such as Fe and Cr can be used in the preparation of (Fe,Cr)O3 type black ceramic pigments, to achieve the harmless resource utilization of SSD, and to provide a new way to develop of cobalt-free black ceramic pigments. In this study, the effects of different Fe/Cr molar ratios in raw materials and calcination temperatures on the preparation of black ceramic pigments were investigated through the solid-phase reaction method assisted by microwave heating using SSD and the chemical reagent Cr2O3 as the main raw materials. The results show that with increasing Cr content in the raw material and calcination temperature, the crystallinity of the solid solution phase in the prepared pigment and the grain size increased gradually. The optimized preparation conditions for the black ceramic pigment are an Fe/Cr molar ratio of 1 and a calcination temperature of 900 °C. Under this condition, the main phase composition of the pigment is the solid solution (Fe1-xCrx)2O3 and spinel. The spinel phase is a regular polyhedron, while the solid solution tends to be a phase with irregular morphology connected by crystal planes. Meanwhile, the pigment has a high absorption intensity and absorption consistency for various bands of visible light, and its band gap is only 1.37 eV. Its color coordinate is highly consistent with that of the achromatic point in the chromaticity diagram, indicating that it has excellent black color rendering performance. Moreover, the prepared pigment has excellent thermal and chemical stability and exhibits great adaptability and colorability to most types of glazes except for B2O3-based glazes.