Effects of critical particle size on properties and microstructure of porous purging materials

Interconnected pores were obtained from packed arrays of particles with similar particles sizes. Four kinds of samples containing the same matrix and different aggregates (diameter sizes of 1.5, 2.5, 3.5 and 4.5 mm) were successfully fabricated through pouring shaping. The effects of the critical particle size on the properties and microstructure of the porous purging materials were investigated. Packing of larger aggregates resulted in larger pores being formed, which facilitated pore linkage, but lowered the apparent porosity of the array. When the aggregate size was 4.5 mm, the sample had a lower porosity of 22.3%, a higher density of 2.94 g/cm3 and a higher air permeability of 24.8 μm2.