Studying the initial stages of gelation process in colloidal silica on basis of synthetic silicates by NMR microimaging and relaxometry

摘要

The acid silicious sols obtained from synthetic silicates were investigated in this work. Using NMR microimaging it was found out the formation of considerable inhomogeneities in optically limpid samples at different stages of gel formation. They were interpreted as silicic acid polycondensation fronts. It was observed the character of spreading and fine structure of the fronts. By means of NMR relaxometry were discovered the some interesting effects at the relaxation dependences in time intervals, correspondingto gel formation transitional stages.