Effect of particle size distribution of raw powders on pore size distribution and bending strength of Al2O3 microfiltration membrane supports

To lower the sintering temperature of Al2O3 microfiltration membrane support, Al2O3 powders with particle size distribution of tri-modal are chosen. The results show that the function of fine Al2O3 grains depends on their agglomeration state: if fine Al2O3 grains distribute discretely, the bending strength of the support increases along with a slight increase in porosity; however, the aggregated fine grains are harmful to both bending strength and pore size distribution of the support. The bridging of medium Al2O3 grains between coarse grains contributes to increase the bending strength, but has less effect on porosity. The addition of medium (and/or fine) Al2O3 powder has less effect on the pore size distribution of the support if only coarse Al2O3 grain forms the support's framework, which suggests a new way to prepare the support with both high bending strength and high porosity at low temperature.