Al2O3-SiO2超微粉的性能分析及应用研究

Performance and application of Al_2O_3-SiO_2 ultrafine powder

以水玻璃和工业氯化铝为原料，采用沉淀法和真空冷冻干燥技术，在实验室制备Al2O3-SiO2二元超细粉体材料，采用XRD、TG-DSC、物理吸附仪等对其进行表征，并将其添加于莫来石-刚玉质耐火浇注料中进行性能分析。结果表明，用沉淀法和真空冷冻干燥技术可获得含迪开石相具有微孔的超细粉体；Al2O3-SiO2超细粉经1200℃处理全部生成纳米晶莫来石；在莫来石-刚玉质耐火浇注料中加入0．25％～0．75％的Al2O3-SiO2超细粉有利于浇注料试样力学性能的提高；SEM分析表明，加入0．5％超细粉，试样的基质与骨料在1000℃时结合成一体，因而具有较好的力学性能。

Al2O3-SiO2 ultrafine powder was prepared from water glass and crystal aluminum chloride by means of precipitation and vacuum freeze drying technology. The powder was characterized after heat treatment under different temperatures by XRD, TG-DSC, physical desorption device, etc. In the meantime, the ultrafine powder was applied to mullite-corundum refractory castable for performance analysis. The results indicate that the ultrafine powder in nanometer scale containing dickite and micropore can be obtained by precipitation and vacuum freeze drying technology. The XRD analysis shows that Al2O3-SiO2 ultrafine powder obtained from the experiment has been turned into nanocrystal mullite after being heated at 1 200℃. The addition of a small amount of Al2O3-SiO2 ultrafine powder （0.25-0.75%） can improve the mechanical properties of mullite-corundum castable. However, when the quantity exceeds 0.75%, the effect is not remarkable due to the vibrating flow value decrease. Fractographic analysis of the sample using SEM indicates that the matrix material of the sample containing 0.5% ultrafine powder has combined with aggregate at 1 000℃ ; hence the superior mechanical performance.