镁铝离子共存硅酸体系的聚合行为

通过对镁铝离子共存硅酸体系中硅酸胶凝时间、单硅酸聚合反应速率以及凝胶热性能的研究，得出：在pH<；4的微酸性条件下，硅酸体系的胶凝时间随镁铝离子共存浓度的增大而减小，且铝离子在对硅酸体系的促凝过程中起主要作用。镁铝离子共存硅酸体系的单硅酸反应速率常数比不含金属离子硅酸体系的有所增大，计算得出MA_0.1+0.1硅酸体系的单硅酸平均速率常数为：k₀=7.28×10^-4，k₁=5.62×10^-4。镁铝离子共存硅酸体系凝胶的晶化转变温度与晶型转变温度，相较于不含金属离子硅酸体系的均有所降低，根据热重曲线计算出MA_0.1+0.1硅酸体系水合二氧化硅的化学式为：SiO₂·0.556 H₂O。

Polymerization behavior of silicic acid with coexisting magnesium and aluminum ions

Gel time, polymerization rate of monosilicic acid, and thermal performance of gel of silicic acid system with coexisting Mg²⁺ and Al³⁺ ions were investigated. At pH<4, gel time of silicic acid system decreased with the increase of coexisting concentration of Mg²⁺ and Al³⁺ ions, and Al³⁺ ions played an important role in the coagulation process. Polymerization reaction rate constant of monosilicic acid, for silicic acid system with coexisting Mg²⁺ and Al³⁺ ions, was higher than that for silicic acid without metallic ions, and average rate constant for MA_0.1+0.1 system was k₀=7.28×10^-4, k₁=5.62×10^-4. Crystallization temperature and crystal transformation temperature of silicic acid system with coexisting Mg²⁺ and Al³⁺ ions were lower than those of silicic acid without metallic ions, and chemical formula of hydrated silicon dioxide for MA_0.1+0.1 system calculated by TG curve was SiO₂·0.556 H₂O.