The effect of mechanochemical activation on the reactivity in the MgO-Al2O3-SiO2 system

Samples of the MgO-Al2O3-SiO2 ternary system, constituted by 28.5 mol% of MgO, 28.5 mol% of Al2O3 and 43 mol% of SiO2, were activated in a roll mill and calcined at different temperatures. The influence of the grinding time, the used SiO2 precursor and activation medium, furthermore the mass ratio between the powdered sample and zirconia cylinders was investigated on the reactivity of the MgO-Al2O3-SiO2 ternary system. FTIR spectra and the X-ray powder diffraction patterns indicates the formation of Mg(OH)2 at 393 K, of forsterite (MgSi2O5) and enstatite (MgSiO3) at 1223 K and of spinel (MgA12O4) between 1223 and 1523 K in some samples. The presence of cordierite (Mg2A12Si5O18) was observed at 1523 K, a reaction pathway concerning its formation was proposed.