硅溶胶型壳中NH_4Cl水溶液的硬化机理

Hardening Mechanism of NH_4Cl Aqueous Solution in Silica Sol Shell Molding

采用胶态浇注成型法成型,不添加NH4Cl水溶液的硅溶胶型壳的硬化时间为38 h;添加NH4Cl水溶液的硅溶胶型壳的硬化时间仅为1 h,同时有一种刺激性气味气体产生,表明NH4Cl水溶液有促进硅溶胶型壳硬化的作用,并且发生了化学反应,放出NH3。借助硅溶胶的结构、胶凝原理、热力学和动力学理论,分析了NH4Cl水溶液在硅溶胶型壳成型中的硬化机理。

When the colloidal casting processing technique was used to mold, the hardening time of silica sol shell without NH4Cl aqueous solution was 38 hrs, Whereas the hardening time of silica sol shell with addition of NH4Cl aqueous solution was only lhr, and a gas with pungent smell was generated at the meantime. The results show that NH4Cl aqueous solution plays a role in accelerating silica sol shell-hardening, and a chemical reaction takes place and thus emits NH3. The hardening mechanism of NH4Cl aqueous solution in silica sol shell molding was studied through analyzing the silica sol structure, coagulation principle, thermodynamics and dynamics