Fabrication and Microstructure Characterization of Continuous Porous TiO₂/Al₂O₃Composite Membrane

Using a multipass extrusion process, continuous porous Al2O3 body (similar to 41% porosity) was produced and used as a substrate to fabricate continuous porous TiO2/Al2O3 composite membrane. The diameter of the continuous pores of the porous Al2O3 body was about 150 mu m. The TiO2 nanopowders dip coated on the continuous pore-surface Al2O3 body existed as rutile and anatase phases after calcination at 520 degrees C in air. However, after aging of the fabricated continuous porous TiO2/Al2O3 composite membrane in 20% NaOH at 60 degrees C for 24 h, a large number of TiO2 fibers frequently observed on the pore surface. The diameter of the TiO2 fibers was about 150 nm having a high specific surface area. However, after 48-h aging period, the diameter of the TiO2 fibers increased, which was about 3 mu m. Most of the TiO2 fibers had polycrystalline structure having nanosized rutile and anatase crystals of about 20 nm.