Porous ceramic support of coated alumina prepared by low-temperature sintering

Two kinds of alumina powders with a mean particle size of ~22 μm (micro) and ~0.5 μm (submicrometer) respectively were chosen as the starting materials. Two methods to treat the alumina powders suitable for macroporous support preparation were used. With one method, the powder mixture of the micro and submicrometer alumina powders is obtained through simple mechanical mixing, and with the other, the micrometer alumina is coated with submicrometer alumina via heterocoagulation process. By using these two post-treated alumina powders, respectively, two kinds of disk supports were prepared by dry-pressing. The effects of the sintering temperature on the properties of these supports, such as the bending strength, pore structure and pure water flux, were studied. The results show that the bending strength of the support prepared with coated alumina (hereafter referred to as support CS) is higher than that of the support prepared with the powder mixture. The support CS sintered at 1 550°C exhibits higher mechanical strength and permeability as follows: a bending strength of 34.2 MPa and a pure water flux of 205 m³/(m²·h·MPa), and its average pore size and porosity are 2.34 μm and 34%, respectively.