Abstract: Interconnected porous mullite ceramics were fabricated by freeze-drying process combining starch consolidation,using kaolin,aluminum hydroxide as starting materials,starch as consolidator and binder and Y2O3 as sintering additive.The effects of starch content on the slurry rheological property,porosity,pore-size distribution,microstructure and mechanical strength of porous mullite ceramics were investigated.It is found that the viscosity of slurry increased significantly with the starch addition increased from 15.84vol; to 20.59vol;,but decreased dramatically with the increase of shear rate and tended to be steady,suggesting a slight shear-thinning behavior.With the starch content increasing,the pore size of the ceramics decreased,displaying a homogeneous pore size distribution from bimodal to unimodal.Meanwhile,the porosity changed slightly and kept in the range of 61.5;-66.2;.In addition,when the starch content increased to 15.84vol;,the compressive strength of ceramics increased to the maximum values of 9.5 MPa,porosity also increased to 65.7;.However,the compressive strength tend to decease with the further increase of starch content.

Key words: Interconnected porous mullite ceramics were fabricated by freeze-drying process combining starch consolidation,using kaolin,aluminum hydroxide as starting materials,starch as consolidator and binder and Y2O3 as sintering additive.The effects of starch content on the slurry rheological property,porosity,pore-size distribution,microstructure and mechanical strength of porous mullite ceramics were investigated.It is found that the viscosity of slurry increased significantly with the starch addition increased from 15.84vol; to 20.59vol;,but decreased dramatically with the increase of shear rate and tended to be steady,suggesting a slight shear-thinning behavior.With the starch content increasing,the pore size of the ceramics decreased,displaying a homogeneous pore size distribution from bimodal to unimodal.Meanwhile,the porosity changed slightly and kept in the range of 61.5;-66.2;.In addition,when the starch content increased to 15.84vol;,the compressive strength of ceramics increased to the maximum values of 9.5 MPa,porosity also increased to 65.7;.However,the compressive strength tend to decease with the further increase of starch content.