Fabrication of porous Al2O3-MgAl2O4 ceramics using combustion-synthesized powders containing in situ produced pore-forming agents

Novel pore-forming agents as well as other starting materials were produced in situ via a solution combustion process and were used to fabricate porous Al2O3-MgAl2O4 ceramics. The relative fuel-to-oxidant ratios (phi(e)) of 1.06, 1.28, 1.49 and 1.70 were achieved by varying the amount of starch in the precursors. Effects of phi(e) on the weight percent of the pore-forming agents in the powders, open porosity and Vickers hardness of the as-prepared porous ceramics were investigated. Experimental results revealed that the weight percent of the pore-forming agents in the powders increased significantly, while porosity of the as-prepared ceramics first increased and then decreased as phi(e) rose from 1.06 to 1.70. Meanwhile, pore size distribution became far narrower and the Vickers hardness of the porous ceramics increased as phi(e) increased. (C) 2011 Elsevier B.V. All rights reserved.