NUMERICAL SIMULATIONS OF SINTERING, APPLICATION TO PARTIALLY DENSIFIED AEROGELS

Following recent scaling theories, the sintering of silica aerogels in modeled starting from computer generated gel structures obtained by d iffusion-limited cluster-cluster aggregation on a cubic lattice. Two s teps compose the sintering process model: a ''dressing'' step in which all particles are replaced by overlapping larger particles and a ''co ntraction'' step in which an adequate length rescaling is performed in order to conserve the total mass. Several quantities are computed dur ing sintering as a function of the aerogel density such as the two cha racteristic cut-off lengths (lower and upper limits of the fractal reg ime) and the specific interface area. Comparison is made with results of similar off-lattice calculations when available. Some of the numeri cal results are compared with experiments on partially densified base- catalysed aerogels.