Influence of infiltration pressure on the window size and relative density of open-cell porous aluminium manufactured by replication casting

Recent advances in cellularporous materials for improved performance in their areas of application require the integral design of their porous structure. In this work, open-cell porous aluminium with pores of spherical geometry and interconnecting windows were fabricated using the replication casting method by infiltrating porous preform formed by packing sodium chloride spheres of two different size ranges (1.4–2.0 mm and 2.0–2.5 mm diameters) with molten aluminium under externally applied differential pressure of between 0.01 and 0.1 MPa. The preform was removed by water dissolution which resulted in the formation of porous materials. The influence of infiltration pressure on the window size and relative density of open-cell porous aluminium manufactured was investigated. The resulting open-cell porous aluminium structures were characterized by using the micro-computed tomography and optical and scanning electron microscopes. The results show that within the range of applied pressure, the relative density of the open-cell porous aluminium structures increases as the infiltration pressure is increased, while the window diameter of the porous samples decreases as the applied pressure is increased. A geometric model based on interaction between poorly wetted sodium chloride particles and molten metal which leads to the formation of windows is proposed for the estimation of window radius of porous metals fabricated by replication casting. The estimated window size based on the geometric model is in good agreement with the measured window diameter of the experimental samples.