Near‐net shape manufacture of macroporous nanosized alumina monolith by aqueous gel casting method

A potentially near‐net‐shape manufacturing procedure for macroporous alumina monoliths with 20%‐75% porosity was presented by gel casting of nano γ‐Al2O3. Although monolith obtained by nano alumina had a high surface area and low sintering temperature, an optimum fraction of micron alumina needed to be added to achieve the proper rheological and mechanical properties of slurries. The preparation parameters including alumina loading, sintering temperature, monomer concentration, and the fraction of nano alumina were investigated. The green densities ranging from 0.66 to 0.86 g cm−3 were obtained by raising alumina loading from 10 to 20 vol%. Depending on the monomer concentration and sintering temperature, the mean pore size ranging from 45 to 412 nm, total porosity (20%–75%), and open porosity varying from 12% to 89% were obtained. The sintered density (from 0.95 to 3.15 g cm−3) and compressive strength (CS) (from 4.2 to 31.46 MPa) were suitable for use in different fields.