Solid solubility of magnesium oxide in aluminoferrite

The state of magnesium oxide (MgO) in cement clinker has a direct impact on its stability and it is therefore important to determine the solid solubility of magnesium oxide in the main minerals of clinker. Aluminoferrite is one of the four main components of clinker. This work studied the state and solid solubility of magnesium oxide in aluminoferrite by replacing the same molar mass of calcium oxide (CaO) with 0·5 mol and 1 mol magnesium oxide; comparisons with a blank sample were made. The samples were analysed by x-ray diffraction, lithofacies analysis and scanning electron microscopy. The results showed that new phases appeared in the system when magnesium oxide was added and the quantity of new phases increased as the content of magnesium oxide increased. The maximum solid solubility of magnesium oxide in the system was determined to be about 4·5%, with most dissolved in a glass phase instead of crystallographic tetracalcium aluminoferrite (C₄AF).