Effect Of Aluminum Doping On The Performance And Microstructure Of Methyl-Modified Sio2 Sol

With methyltriethoxysilane as hydrophobic precursors and aluminum isopropoxide as the aluminum source, the Al2O3/SiO2 sols and their gel materials were prepared. The effects of aluminum content (n(Al)) on the viscosity (eta), density (rho), reaction rate constant (k), Gibbs energies of activation for viscous flow (Delta G*), particle size of Al2O3/SiO2 sols were studied. And the high temperature calcined materials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Scanning electron microscopy (SEM). The results show that, with the increase of n(Al), the eta, n and Delta G* values of the Al2O3/SiO2 sols decrease while the k and rho values and average particle sizes increase. There is strong intermolecular interaction between the Al2O3 and SiO2 sol molecules. The Al-O-Si bond exists in the Al2O3/SiO2 materials before and after calcination at 350 degrees C. Calcination at 350 degrees C in N-2 atmosphere can change the phase structure of Al2O3/SiO2 sample greatly, which can make the gamma-AlOOH in the Al2O3/SiO2 gel material convert to gamma-Al2O3 through dehydration.