论文部分内容阅读
本文研究了酸催化条件下（pH≈3），TEOS（正硅酸乙酯）水解制备二氧化硅干凝胶过程中，不同胶凝速度对所获得的干凝胶表面分形特性的影响，并分析了煅烧处理的影响．实验以盐酸为催化剂，丙酮为溶剂．结果表明，胶凝速度对未经煅烧的二氧化硅干凝胶表面分形维数几乎没有影响，但较慢的胶凝速度下制备的二氧化硅干凝胶在600℃煅烧后，其表面分形维数有较大的降低．改变煅烧温度的实验表明，在600℃以上继续提高煅烧温度，一般二氧化硅干凝胶的表面分形维数可维持到800℃以上不出现显著下降．
In this paper, the effects of different gelling rates on the surface fractal properties of xerogels obtained under acid-catalyzed conditions (pH≈3) and TEOS (tetraethyl orthosilicate) hydrolysis were investigated. The effect of calcination was analyzed. Hydrochloric acid as catalyst and acetone as solvent. The results show that the gelling speed has almost no effect on the surface fractal dimension of the uncalcined silica xerogel. However, the surface fractal of the silica xerogel prepared at a slower gelling speed is calcined at 600 ℃. Dimension has been greatly reduced. Experiments to change the calcination temperature show that the calcination temperature should be increased above 600 ℃. Generally, the surface fractal dimension of the silica gel can be maintained above 800 ℃ without any significant decrease.