以高岭土、氢氧化铝为原料,淀粉为造孔剂和粘结剂,Y2O3为烧结助剂,采用冷冻干燥法结合淀粉固化工艺制备了具有连通开孔结构的莫来石多孔陶瓷.研究了淀粉添加量对浆料前驱体的流变性能、多孔陶瓷的气孔率、孔径分布、显微结构以及力学性能的影响.结果表明:当淀粉含量由15.84vol％增至20.59vol％,浆料前驱体的粘度增加明显;随着剪切速率的增加,浆料前驱体的粘度先显著降低然后趋于稳定,表现为剪切稀化行为.随着淀粉含量的增加,所得多孔陶瓷的孔径尺寸减小,孔径分布趋于均匀,从双峰分布向单峰变化,孔隙率缓慢增加,维持在61.5％～66.2％范围内,当淀粉含量增加到15.84vol％时,抗压强度达到最高值9.5 MPa,孔隙率也达到65.7％.但当淀粉含量进一步增加后,抗压强度有下降的趋势.
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.
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