Gelation on Solid Surfaces in Water Free Na₂O-ZrO₂-SiO₂ Sols

Abstract

Accelerated gelation on the alumina surfaces in the sols of the Na₂O-ZrO₂-SiO₂ system without water addition has been shown by model experiments. From the surface-to-surface adhesion test, it was demonstrated that water-free Na₂O-ZrO₂-SiO₂ sols gelated in 1h-1d period preferentially on/between the contacted alumina surfaces. Formation of gel films was confirmed by BS images and EDX analysis. A similar result was obtained for slide glass plates. Gelation was not observe, however, for PTFE (polytetrafluoroethylene or teflon) plates, which was explained as due to the absence of hydroxyl group or adsorbed water on the PTFE surface.