Preparation and properties of high toughness RBAO macroporous membrane support

Reaction bonding of aluminum oxide (RBAO) is a novel technique for preparing porous alumina. By adapting this manufacturing route, macroporous Al₂O₃ supports with high fracture toughness are prepared for ceramic membrane. The effects of sintering temperatures and aluminum (Al) content on mechanical properties of macroporous Al₂O₃ supports are investigated, especially for the improvement of fracture toughness. When the sintering temperatures increase from 1200 °C to 1600 °C, increments of fracture toughness and bending strength are observed. Sintered at 1600 °C, when Al content is 16 wt%, the maximum value of fracture toughness and bending strength of macroporous Al₂O₃ supports are 2.0 MPa m^1/2 and 137 MPa, respectively, which are 2.0 and 2.6 times than that of the supports without adding any additives. By SEM analysis, many fine Al₂O₃ particles form a network which is beneficial to the improvements of fracture toughness and bending strength. After corroded in nitric acid and sodium hydroxide solutions of 1 mol L^-1 at 80 °C for 168 h, respectively, the mass loss percentage is lower than 1 wt%. And the bending strength keeps at the level of ∼40 MPa which is strong enough to apply in industry. Simultaneously, the toughening mechanism of RBAO macroporous support is also discussed.