Preparation and Characterization of Undoped and Chromia-Doped Porous Alumina Using Different-Sized Particles

Abstract

Highly porous alumina (Al2O3) was prepared by sintering of Al2O3 powder using ammonia bicarbonate (NH4HCO3) as a pore-forming agent and chromia (Cr2O3) as a sintering additive. In order to investigate the influence of particle shape and size on the characterization of sintered porous Al2O3, the starting Al2O3 powders included commercial disk micro-sized powder and synthesized spherical nanopowder. The nanoscale Al2O3 powder was produced via combustion synthesis route. At the optimal pore-forming agent concentration, the porous Al2O3 sintered by nanoparticles had a smaller pore size and a lower total porosity than the one prepared by microparticles. The differences of open porosity and closed porosity between porous Al2O3 synthesized by micro and nano-scale powders with and without Cr2O3 dopant were also discussed. In addition, the compressive strength of porous Al2O3 achieved by nano-sized powders, especially with Cr2O3 dopant, had a higher value in comparison with the one prepared by micro-sized powders.