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 TiO 2 , CaCO 3 and SiO 2 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 TiO 2. 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 TiO 2 as an opacifier as there was no free TiO 2 transformed to rutile at high-temperature calcination. This study provides a feasible solution for the problem of glaze yellowing in substitution of TiO 2 for ZrSiO 4 opacifiers in sanitary ceramics, improving the quality of ceramic glazes. [ABSTRACT FROM AUTHOR]