Mg-O-Si Chemical Bond Formation in Light Burned Magnesia and Fumed Silica Mixture During Mechanical Activation

Mg-O-Si chemical bond formation in a light burned magnesia (MgO) and fumed silica (SiO2) mixture during mechanical activation was investigated by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), magic angle spinning nuclear magnetic resonance (MAS-NMR), and X-ray photoelectron spectroscopy (XPS). Crystallinity and intrinsic structure changes of the starting mixture during high-energy milling were examined by XRD. The formation of new Mg-O-Si chemical bonds of the ground mixture was illustrated by the incorporation of Mg2+ in Si-O-Si linkages, the appearance of new resonance in the 29Si NMR spectrum and the decrease of the Si 2p binding energy. The formation of Mg-O-Si chemical bonds created during grinding partly contributed to the lowered temperature of complete forsterite formation from 1400 to 1100°C.