Synthesis of sphene by TiO2 combined with CaCO3 and SiO2 in solid phase and its application as ceramic opacifier

Synthetic sphene powder (SSP) was prepared using TiO2, CaCO3 and SiO2 via a solid-phase method, and used as an opacifier for sanitary ceramics. The raw materials were calcined at 1200 °C for 2 h, yielding SSP with a main component of sphene and a trace of cristobalite, but no free TiO2. In the optimal conditions of 12% added SSP, calcination temperature of 1100 °C, and holding time of 4 h, the ceramic glaze exhibited high whiteness. The SSP opacifier effectively inhibited the glaze yellowing that occurs when directly adding TiO2 as an opacifier as there was no free TiO2 transformed to rutile at high-temperature calcination. This study provides a feasible solution for the problem of glaze yellowing in substitution of TiO2 for ZrSiO4 opacifiers in sanitary ceramics, improving the quality of ceramic glazes.