Abstract: Porous alumina ceramics were prepared by methods of compression molding , drying and sintering with calcined α-Al2 O3 powder as aggregate , aluminum dihydrogen phosphate as binder and paraffin as molding promoter .The effect of sintering temperature and aluminum dihydrogen phosphate content on microstructure , phase composition , linear shrinkage , porosity and flexural strength were studied.The mechanisms of sintering by phosphate bonding method were discussed .Results show that the phase compositions of porous alumina ceramics are α-Al2 O3 and AlPO4 .Porous alumina ceramics are formed by AlPO4 bonding among alumina particles at low temperature .With increasing aluminum dihydrogen phosphate content , the linear shrinkage and flexural strength increase smoothly , while the porosity decrease .The existence of AlPO 4 accelerates the liquid-phase sintering among the alumina particles at high temperature .The linear shrinkage and flexural strength increase sharply with increasing sintering temperature , and the porosity decrease obviously .

Key words: Porous alumina ceramics were prepared by methods of compression molding , drying and sintering with calcined α-Al2 O3 powder as aggregate , aluminum dihydrogen phosphate as binder and paraffin as molding promoter .The effect of sintering temperature and aluminum dihydrogen phosphate content on microstructure , phase composition , linear shrinkage , porosity and flexural strength were studied.The mechanisms of sintering by phosphate bonding method were discussed .Results show that the phase compositions of porous alumina ceramics are α-Al2 O3 and AlPO4 .Porous alumina ceramics are formed by AlPO4 bonding among alumina particles at low temperature .With increasing aluminum dihydrogen phosphate content , the linear shrinkage and flexural strength increase smoothly , while the porosity decrease .The existence of AlPO 4 accelerates the liquid-phase sintering among the alumina particles at high temperature .The linear shrinkage and flexural strength increase sharply with increasing sintering temperature , and the porosity decrease obviously .