Nano-sized amorphous Al2O3-2SiO2 powder was prepared by a sol-gel method coupled with azeotropic distillation. The structure of the powder was investigated by DTS, BET, TEM, FT-IR, TG-DTA and XRD, showing that n-butanol azeotropic distillation could effectively remove water from the aluminosilicate gels and prevent the formation of hard agglomerates in the drying process. The average particle diameter of the powder was about 70 nm. The largest BET specific surface area of the powder was 669 m2/g. To examine the alkali-activation reactivity of the powder, alkali-activation tests were performed with the powder reacting with sodium silicate solution, The synthetic powder was found to be highlv reactive.
Guangjian ZhengXuemin CuiWeipeng ZhangZhangfa TongFeng Li
研究了热处理工艺对碱激发矿渣(alkali active slag cement,AASC)胶凝材料硬化体结构和介电性能的影响。研究结果表明,随着热处理温度的提高,胶凝材料硬化体的介电常数和介电损耗逐渐下降,当热处理温度达到400℃左右,介电损耗下降到10-2数量级水平,此时影响胶凝硬化体介电损耗的主要因素是胶凝材料硬化体中的自由水、化学水等;当热处理温度达到750℃左右,介电损耗下降到10-3数量级水平,与电子封装陶瓷材料接近;XRD和SEM分析结果也表明,随着碱激发方式的改变,双碱激发胶凝材料硬化体在750℃左右发生析晶现象,径向线收缩约为6%,有陶瓷化倾向;胶凝硬化体介电损耗在该阶段急剧降低主要是由碱矿渣胶凝材料相组成和微观结构变化造成的。
Attempts had been made to synthesize Al2O3-2SiO2 nanopowders by sol-gel method with tetraethoxysilane（TEOS） and aluminum nitrate（ANN） as the starting materials.DTS,TEM,SEM and BET were employed to study the effects of process parameters on the size,specific surface area and structure（morphology） of powders.The alkali-activation reactivity of the powders was tested for manufacturing geopolymers and their hydrothermal reactions were performed for fabricating zeolites.The results show that the optimum process parameters and drying method for preparing Al2O3-2SiO2 nanopowders are as follows：the molar ratio of water and ethanol to TEOS are 0：1 and 12：1 respectively at synthetic temperature of 50 ℃ and the drying method is azeotropic distillation with microwave drying.The average particle diameters of the powders were about 70 nm and the largest BET specific surface area was up to 669 m^2·g^-1.The compressive strength of the geopolymer and the calcium exchange capacity（by CaCO3） of NaA zeolite prepared with the powders reached to 29 MPa and 366 m^2·g^-1 respectively.
