水热法制备水化硅酸钙纳米粉体

Hydrated Calcium Silicate with Nm-order Size Manufactured by Using Dynamic Autoclaved Technology

通过动态水热合成方法,采用低成本的硅藻土与生石灰作原料,在120℃恒温恒压,并分别在4h、7h、10h的蒸压制度下制备出水化硅酸钙纳米粉体。并用XRD、BET、SEM、TEM等现代测试手段对制得的水化硅酸钙粉体进行了性能测试。结果表明:该纳米粉体结晶度很低、比表面积极大,粉体颗粒的粒径大小主要在50nm左右;硅质原料和钙质原料的水热合成反应机理主要为溶解-沉淀反应;恒温时间对水热合成产物影响较大,恒温7h时Ca(OH)2反应殆尽,恒温10h时,原料中还有少量的SiO2尚未反应完毕;恒温10h时,纳米粉体的主要产物为水化石榴石、半结晶态的C-S-H(1)、硬硅钙石的前趋物以及Al2SiO5。

Through hydrothermal synthesis process, a kind of hydrated silicate powder with nm-order size can be manufactured by cheap diatomaceous earth as the siliceous materials and lime calcium material under the conditions of 120 ℃ in the autoclave. The autoclave schedules are 4 h,7 h and 10 h respectively.By means of XRD, Nitrogen absorption, SEM, TEMetc. measurement technology,the feature, particle size and properties of hydrated calcium silicate powder are measured. The hydrated silicate powder owns poor degree of crystallinity and extremely larger specific surface area.The dimension of hydrated silicate powder with nm-order size is about 50 nm; the mechanism of autoclaving reaction of calcium and silica raw materials primarily is solution-deposit reaction; the autoclave schedule has a great effect upon synthetic products. Ca(OH)_2 has been reacted compeletely when the autoclave schedule is 7 h, yet the products still include a few of SiO_2 when the autoclave schedule is 10 h; the primary products include C_3ASH_4, hemicrystalline C-S-H(1), predecessor of Ca_6\[Si_6O_(17)\](OH)_2,and Al_2SiO_5 when the autoclave schedule is 10 h.