利用溶胶-凝胶酸碱二步催化法和常压干燥法制备了掺有不同含量TiO2粉末、自制SiO2干凝胶纳米粉末和微玻璃纤维的SiO2干凝胶.采用氮气吸附脱附实验,由经典FHH方程计算得到各掺杂SiO2干凝胶的表面分形维数.比较研究了不同添加物对SiO2干凝胶密度、孔结构和比表面积等的影响,并根据de Boer理论判断了孔隙的形状.结果表明,添加物不仅能够增强SiO2干凝胶的强度,抑制湿凝胶干燥过程中的收缩,而且能改变其孔隙结构和颗粒堆积方式.SiO2纳米颗粒能够降低SiO2干凝胶的比表面积,且使其孔径分布逐渐变宽;而TiO2粉末和短切纤维,能够提高SiO2干凝胶的比表面积,最终获得的改性SiO2干凝胶最高比表面积可达1064.96 m2/g.各个样品的表面分形维数均在2.4～2.5之间.
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