MgO烧结助剂对氧化铝多孔陶瓷结构和性能的影响

Effect of MgO Sintering Additives on Structure and Performance of Al_2O_3 Porous Ceramic

以叔丁醇为溶剂,采用凝胶注模成型工艺于1 500℃保温2 h烧结制备出高气孔率、高强度、低热导率氧化铝多孔陶瓷。研究了氧化镁烧结助剂对氧化铝多孔陶瓷气孔率、气孔尺寸及分布、耐压强度和室温热导率的影响。结果表明：当氧化镁添加量从0.5%（质量分数）增加到2.0%时,气孔率的变化范围为64.65%~73.28%;气孔尺寸分布均匀,平均孔径为0.91~1.30μm;加入MgO后,陶瓷具有较高的耐压强度,介于14.1~36.2 MPa之间,室温热导率[最低可达0.55 W/（m？K）]比相应的致密陶瓷[室温热导率约为30 W/（m？K）]低2个数量级左右。

Porous alumina ceramics with high porosity, high compressive strength and low thermal conductivity were fabricated by gel-casting with tert-butyl alcohol as a solvent and subsequent pressure-less sintering at 1 500 ℃ for 2 h. The effect of sintering additives （i.e., MgO） on the porosity, open porosity, pore size distribution and microstructure of porous alumina ceramics was investigated. The results show that the porosity increases from 64.65 % to 73.28 % when the MgO fraction increases from 0.5% （in mass fraction） to 2.0%. The uniform pore size distribution with the mean pore size ranging from 0.91-1.30 μm is obtained. The compressive strengths of porous alumina ceramics （i.e., 14.1-36.2 MPa） can be improved by the addition of MgO. The thermal conductivity of porous alumina ceramics （i.e., 0.55 W/（m-K）） is two order of magnitude lower than that of dense alumina ceramics （i.e., 30 W/（m-K）） at room temperature.