Solid-phase synthesis of perovskite using spent SCR catalyst and calcium carbonate and its application as ceramic opacifier

Abstract

In this study, the synthetic perovskite powder (SPP) was produced by solid-phase method using S-SCR and calcium carbonate (CaCO3), and its structure, morphology, and application as ceramic opacifier were studied. The results show that SPP with a single perovskite phase can be obtained by grinding and calcining raw materials. Adding SPP as opacifier of sanitary ceramics for firing, a white ceramic glaze with excellent opacity was obtained. Among the glaze chromaticity values, L* is 93.09, a* is −0.76 and b* is 4.98. The opacity of the glaze is stronger than that of the glaze using ZrSiO4 and TiO2 as opacifiers, and the whiteness of the glaze is significantly greater than that of glaze with TiO2. The ceramic glaze layer using SPP is mainly composed of glass phase, titanite and quartz, of which titanite is the opacified phase. Importantly, TiO2 is pre-combined into perovskite to make it unable to freely and avoid its own high-temperature phase transition reaction, which is the mechanism to inhibit the yellowing of glaze surface caused by direct use of TiO2. This study can play a positive role in improving the utilization value of S-SCR and eliminating the yellowing of ceramic glazes using TiO2 as opacifier.