TEXTURE CONTROL OF CLAY-AEROGEL THROUGH THE CRYSTALLIZATION PROCESS OF ICE

Abstract

Since the texture of the clay-aerogel is the replica of ice crystals appeared inthe process of freezing, an attempt has been made to control the aerogel texture by varying some factors related to the ice crystallization. As was expected, OM and SEM observations of the aerogels indicated that the size and the shape of a pore in the aerogel was strongly dependent on both the concentration of clay suspension and its freezing rate in the ranges from 5 to 20 wt% and from 1×10^-1 to 1×10^-3 ml/sec, respectively. For decreasing the concentration and the freezing rate of the clay suspensions, the shapes of pores changed from a polygonal cell to a thin lens. The pores tended to be arranged almost parallel to the heat-flow direction. By the heat-treatment at high-temperatures up to at least 800°C, the aerogel still retained its texture and strength, although the shrinkage was not avoidable.