溶胶-凝胶法制备镁掺杂的硅灰石化合物及其相形成机理与模型

Preparation and phase formation mechanism of CaSiO_3 doped with Mg/CaSiO_3 by sol-gel method

以硝酸钙、硝酸镁、正硅酸乙酯为先驱体,利用溶胶-凝胶法合成镁掺杂的硅灰石(Mg/CaSiO3)陶瓷粉体,研究了体系的溶胶-凝胶机理、物相和微观形貌随煅烧温度的变化规律,建立了晶相形成与晶粒长大模型。结果表明:溶胶系统通过正硅酸乙酯的水解与聚合形成凝胶网络,钙离子与镁离子没有参与凝胶网络的形成而是均匀镶嵌在凝胶网络内;固定干凝胶的煅烧时间为1h,当煅烧温度低于800℃时,主要发生硅氧硅键的断裂,晶相形成少,当煅烧温度高于900℃时,晶相大量生成,颗粒呈球状并因高的比表面能而产生团聚;粉体粒径随着煅烧温度的升高经历了先变小后增大的过程。

By using Ca （NO3） 2 · 4 H2 O, Mg （NO3） 2 · 6 H2O and Si （OC2 H5 ） 4 as precursors, the mechanism of Mg/CaSiO3 prepared by the sol-gel method was studied. Based on phase composition, micromorphology and calcination temperature, a model of phase formation and grain growth was established. The results showed that network of gel was formed through the hydrolysis and aggregation of Si（OC2H5）4. Ca^2＋ and Mg^2＋ were embedded in the gel network. When the calcination temperature of the gel was below 800℃, a small amount of crystal phases were formed, and the grain size reduced gradually with increasing calcination temperature due to the break of Si O--Si bond in the network. When the calcination temperature was higher than 900℃, a large amount of crystal phases were formed and the grains grew with the increase of the calcination temperature.