利用海藻酸钠的离子凝胶过程,采用溶剂置换结合冷冻干燥的工艺,成功制备了具有高度有序六方排列的直通孔多孔氧化铝陶瓷,整个工艺过程及所使用的原料都是环境友好的。研究结果表明,1500℃烧结2 h样品的孔径尺寸在200μm左右,且与固相含量的关系不大,而孔壁上存在0.3μm~0.5μm的小孔。通过控制浆料中氧化铝的固相含量可以对材料的性能进行有效地调控,研究表明,随着固相含量从5wt%提高到15wt%,材料的密度从0.87 g/cm3提高到1.16 g/cm3,渗透率从2.57×10-11m2下降到2.16×10-11m2,而抗压强度从(18.9±3.2) MPa提高到(44.2±5.4) MPa,平行孔道方向的热导率从2.1 W/(m·K)提高到3.1 W/(m·K),而垂直孔道方向的热导率从1.3 W/(m?K)提高到1.7 W/(m·K),并且平行孔道方向热导率的增加幅度要明显大于垂直孔道方向。
Alumina ceramic bodies with high porosity characterized by highly ordered and unidirectional oriented pores were successfully fabricated using the ionotropic process of sodium alginate by solvent exchange subsequently with freeze-drying. It is important to point out that the whole process and raw materials are eco-friendly. The average unidirectional pore size of samples sintered at 1500℃ for 2 h is 200μm with minor porosity in the pore walls with average pore size of 0.3-0.5μm. The properties of samples can be adjusted by controlling the solid loading in slurry. As the solid loading increasing from 5wt% to 15wt%, the density and compressive strength increased from 0.87 g/cm3 to 1.16 g/cm3 and from (18.9±3.2) MPa to (44.2±5.4) MPa, respectively with permeability de-creasing from 2.57×10-11m2 to 2.16×10-11m2. In addition, with the solid loading increasing from 5wt% to 15wt%, the conductivity of the direction parallel and perpendicular to the unidirectional pores increased from 2.1 W/(m·K) to 3.1 W/(m·K) and from 1.3 W/(m·K) to 1.7 W/(m·K), respectively.
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