Investigation of CaO/MgO on the formation of Anorthite, Diopside, Wollastonite and Gehlenite phases in the fabrication of fast firing ceramic tiles

Abstract

In this research, the effect of CaO/MgO ratio as the principal oxides activating reactions during fast firing of ceramic tiles on the transformations and formation of phases such as Anorthite, Diopside, Wollastonite, and Gehlenite was studied. Calcium carbonate and Talc/dolomite powder were selected as the sources of CaO and MgO, respectively. After forming with the press, the mixtures were dried, and the bodies were sintered. XRD, XRF, Dilatometry, and SEM/FESEM analysis methods were used to study the microstructural transformations, chemical and physical reactions in the microstructure, and final physical properties of the samples. The X-ray diffraction test identified the phases of the constructed bodies. The weight percentage of the constituent phases was calculated using the MAUD software. Studies indicated that the weight percentage of the Anorthite phase increased by decreasing the CaO/MgO ratio. In addition, the thermal expansion coefficient decreased with the reduction of the CaO/MgO ratio. The lowest coefficient of thermal expansion (7.69 × 10-6 (1/°C)) was reported. Microstructural studies demonstrated that the harmful phase of Gehlenite was removed from the final microstructure, and the Anorthite phase was increased (up to 10 wt%) by fine-graining the primary sources of calcium carbonate and Talc. Furthermore, crystals of the Anorthite phase grew more.