Making Porous Alumina Ceramic By Foaming Method

The porous alumina ceramic can be used as catalyst carrier materials, filtering materials and high refractory materials. There are a lot of methods to produce porous alumina ceramics. Protein foaming-consolidation method for preparing porous alumina was used in this paper. The protein which is friendly to environment is both consolidating and foaming agent.The slurries were prepared with different solid loadings, water and foaming agent. The effect of amount of foaming agent, stirring time and the speed of stirring on the porosity and strength of porous alumina ceramic were analyzed by orthogonal experiment and then ascertaining the best technological parameters. The porous alumina ceramic with different desity was observed by changing the solid loading, besides, the effect of different solid loading on microstructure and mechanical properties was investigated. For the other hand, the effect of the material which was prepared with aluminium hydroxide instead of alumina partially on mechanical properties was also studied.The decomposition behaviour of protein and aluminium hydroxide was investigated by TG-DSC. Microstructure of the samples, including pore distribution and size, was investigated using SEM. Compression strength was studied by High Temperature Material Tester.The best technological parameters were on 25% amount of foaming agent, three hours of stirring and 160n/min of stirring speed by orthogonal experiment. The rate of porosity of the porous alumina ceramic with different density by different solid loadings was from 20% to 65%.Aluminium hydroxide was added as a substitution of Alumina. The relationship of contents of aluminium hydroxide, microstructure and properties was conducted. The investigation showed that the compression strength and porosity were increased, when 20% Alumina had been instead by aluminium hydroxide. The porous alumina ceramic with a lot of closed pores which were well-distributed was observed by using nanometer alumina powder. And the ceramic with 1Mpa compression strength can be used on high temperature refractory materials.