The structure and permeability of the disordered layer prepared by freeze-casting

Asymmetric ceramic membranes with disordered layer prepared by directional freeze-casting can be used as filter materials. However, there are few research achievements on the structural and permeability of disordered layers. Here, we obtained alumina asymmetric ceramic membranes with different disordered layer by adjusting the amount of alumina in the ceramic slurry. The results show that there are two kinds of structures in the disordered layer: spherical micropores and interconnected meshy pores, which lead to the change of airflow state. With the increase of the alumina content, the pore size of the disordered layer decreases and the network structure becomes complex, resulting in the decrease of the velocity of the inertial flow. The filter resistance of disordered layer increases obviously, but its proportion in the total filter resistance increases first and then decreases. The permeability is related to the pore size, specific surface area and channel complexity of the membrane.