泡沫注凝法制备刚玉-莫来石多孔陶瓷

Preparation of porous corundum-mullite ceramics by foam-gel casting method

以T60板状刚玉粉(d50=10.74μm)、ZTP-200氧化铝微粉(d50=4.96μm)、RG4000煅烧氧化铝微粉(d50=1.46μm)和NS-30型硅溶胶为原料,采用泡沫注凝法制备了刚玉-莫来石多孔陶瓷,主要研究了粉料粒度级配(d50分别为1.46、4.96、10.74μm的三种氧化铝粉料的质量分数分别为44%、26%、30%,36%、28%、36%,30%、29%、41%,21%、29%、50%)和浆料中硅溶胶加入量(质量分数分别为0、2%、4%)对坯体的烧后收缩及烧后试样的致密度、常温耐压强度、热导率、相组成和显微结构的影响。结果表明:1)d50=10.74μm的粗颗粒加入量增加,试样的烧后线收缩率、致密度和常温耐压强度减小;2)硅溶胶加入量增加,试样的烧后线收缩率和体积密度减小,但由于SiO2与Al2O3反应生成莫来石,试样的常温耐压强度变化较复杂;3)泡沫注凝法制备的刚玉-莫来石复相多孔陶瓷具有球形孔结构,平均孔径约为140μm,其性能如下:烧后线收缩率9.29%,体积密度0.78 g·cm-3,显气孔率79.8%,常温耐压强度25.3 MPa,1 000℃(热面温度)下的热导率为0.481W·m-1·K-1。

The porous corundum-mullite ceramics were prepared by foam-gel casting method using T60 tabular corundum powder（ d50 = 10.74 μm ）, ZTP-200 alumina micropowder （ d50= 4.96 μm）, RG4000 cal-cined alumina micropowder（ d50 = 1.46 μm） and grain size distribution and the silica sol additions NS-30 silica sol as starting materials. Effects of powder （0% ,2% and 4% ,in mass,respectively） in the slurry on the linear shrinkage rate on heating of green bodies and the bulk density, cold crushing strength ,thermal conductivity, phase compositions and microstructure of the fired specimens were mainly researched. The results show that：（ 1 ）with the increase of the coarse particles （ d50 = ]0.74 μm） ,the linear shrinkage rate, bulk density and cold crushing strength decrease; （2）with the increase of silica sol,the linear shrinkage rate and bulk density decrease, but the cold crushing strength varies complicatedly due to the generation of mul-lite from the reaction between SiO2 and Al2O3;（3）porous corundum-mullite ceramics prepared by foam-gel casting method have the following properties.spherical pore structure with the average aperture of 140 μm, linear shrinkage rate of 9.29%, bulk density of 0.18 g · cm^-3, apparent porosity of 79.8%, cold crushing strength of 25.3 MPa and thermal conductivity of 0.481 W · m^-1 · K^-1 at 1 000 ℃ （hot face temperature）.