硅酸盐学报

海藻酸钠冷冻干燥制备环保型直通孔多孔氧化铝陶瓷

作者：孙阳1 2 薛伟江2 黄勇2 孙加林1 周国治1

单位：1. 北京科技大学材料科学与工程学院北京 100084 2. 新型陶瓷与精细工艺国家重点实验室清华大学材料科学与工程学院北京 100084

关键词：直通孔氧化铝冷冻干燥海藻酸钠

分类号：TU528.042.2

出版年,卷(期):页码：2015,43(6):709-715

DOI：10.14062/j.issn.0454-5648.2015.06.01

摘要：

将海藻酸钠、氧化铝混合制成的浆料定向冷冻，使水定向结冰成孔，再对坯体进行冷冻干燥，使冰升华留下的孔隙结构得以保存，制备具有直通孔结构氧化铝多孔陶瓷。气孔率为66.7%的多孔氧化铝陶瓷具有比传统氧化铝泡沫陶瓷高10倍的渗透率。利用固相体积含量25%的浆料制备的多孔陶瓷抗压强度达到16.03 MPa。通过在原料中加入天然无毒的海藻酸钠作为黏结剂，不仅使整个工艺过程和原料都环境友好，而且使干燥后的坯体具有一定强度，可以满足搬运和机加工的要求。通过控制浆料的黏度和流动性以及分散剂加入量，获得均匀的孔隙结构。此外，还研究了固相含量、烧结温度对气孔率、压缩强度及渗透率等性能的影响。随着固相含量从30%降低到20%，样品的气孔率从61%提高了到72%，而压缩强度从16.03 MPa下降到3.42 MPa，渗透率从0.19×10–11 m2提高到4.51×10–11 m2。随着烧结温度从1 300 ℃提高到1 500 ℃，材料的气孔率从69.72%下降到67.02%，而压缩强度从4.45 MPa提高到18.66 MPa，渗透率从4.51×10–11 m2下降到4.09×10–11 m2。

Alumina porous ceramics were prepared via unidirectional freezing of alumina/sodium alginate slurry and subsequent freeze-drying and sintering. The permeability of the obtained porous ceramics with the porosity of 66.7% is more than ten times greater than that of Al2O3 foams prepared through a conventional process. The compressive strength of the sample with the solid loading of only 25% is 16.03 MPa. The porous ceramics with such a satisfactory strength and complex pore structure can be used in various applications such as fuel cell electrodes, catalysts support and high efficient filtering. Sodium alginate was used as a toxic-free binder for the preparation, making the process environmental friendly and increasing the green body strength. The uniformity of structure is affected by the fluidity and viscosity of alumina slurry. The addition of a dispersant can improve the viscosity of slurry and the uniformity of microstructures. In addition, the effects of solid loading and sintering temperature on the pore size distribution, compressive strength and permeability were also investigated. As the solid loading decreasing from 30% to 20%, the porosity increased from 61% to 72%, compressive strength decreased from 16.03 to 3.42 MPa, permeability increased from 0.19×10–11 m2 to 4.51×10–11 m2. Furthermore, as the sintering temperature increased from 1 300 to 1 500 ℃, the porosity decreased from 69.72% to 67.02%, the compressive strength increased from 4.45 to 18.66 MPa, permeability decreased from 4.51×10–11 m2 to 4.09×10–11 m2.

基金项目：

“973”国家重点基础研究发展计划—陶瓷的高效近终形成形技术及缺陷控制(2006CB605207-2)资助。

作者简介：

孙阳(1956—)，男，博士研究生。

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