Effect of kaolin addition on the sinter-crystallisation kinetics of compacts of a crystallising frit

Abstract

Non-isothermal techniques were used to study the sintering and crystallisation kinetics of an anorthoclase- and diopside-devitrifying frit and mixtures of this frit with a commercial kaolin. Raising kaolin content was verified to delay sintering and crystallisation and to increase the degree to which both processes overlapped, which decreased the sinterability of the material. In addition, raising kaolin content lowered the resulting diopside content, which cancelled out for the mixture with 16 wt% kaolin, while the shape, size, and composition of the anorthoclase crystals also changed. The kinetic parameters of the sinter-crystallisation processes were determined, and a model was developed that appropriately describes sintering kinetics. The model assumes the process develops in two parallel, partly overlapping stages, each of which can be described by the Kohlrausch–Williams–Watts (KWW) relaxation function.