由铁铝酸钙水化生成钙矾石的动力学  

KINETICS OF ETTRINGITE FORMATION FROM CALCIUM ALUMINOFERRITE HYDRATION

作　　者：陈益民[1] 

机构地区：[1]中国建筑材料科学研究院,北京100024

出　　处：《硅酸盐学报》2000年第4期303-308,共6页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金!( 590 72 0 93);全国建材行业科技发展基金

摘　　要：定量研究了石膏与C4 AF或C6AF2 量的比从 1 /3到 4 /1 (以摩尔计 )在室温水化生成钙矾石的动力学 .结果表明 :在DTG曲线上AFt主峰所含 2 6H2 O对应于其结构式中 2 6个以H2 O状态结合较弱的结晶水 ,AFt中Fe2 O3 对Al2 O3 取代量为 2 0 %～ 2 5% .得出由铁铝酸钙水化生成AFt的反应方程式 .在反应动力学中引入反应物颗粒尺寸分布与反应率的关系 .将铁铝酸钙表面反应深度与反应率的关系α(x)与实测的反应率与时间关系α(t)相对照 ,求出了反应深度随时间变化规律 :由铁铝酸钙水化生成AFt的反应自铁铝酸钙表面向内部逐层进行 ,反应深度随时间呈线性增长 .Kinetics of ettringite formation at room temperature from hydration of the mixtures with mole ratio of CaSO 4·2H 2O/C 4AF or C 6AF 2 from 1/3 to 4/1 was studied by DTG, XRD, SEM and EDAX. It is concluded that the main peak in DTG curve of AFt contains 26H 2O,which corresponds to 26 H 2O weakly constructed in AFt structure. The amount of Fe 2O 3 replacing Al 2O 3 in AFt is 20%—25% in the case of C 4AF and C 6AF 2. A model of the reaction kinetics for sphere particles with a radius distribution, (r) , is established. The relationship between the reaction extent, α ( x ),and the reacted depth from the surface of ferrite particles, x , can be expressed as α(x ) =∫ x 0(r)d r +∫ R x[1-(1- x/r ) 3] (r )d r . By comp_aring α(x ) with α(t ) that is determined by experiment the relation between the reacted depth and time, t , can be obtained. It is showed that the reaction of AFt formation takes place from the surface of ferrite to its inner and the hydrated depth from the surface of ferrite increases with time at a constant speed of 0.018 0 μm/h for C 4AF and 0.005 75 μm/h for C 6AF 2.

关 键 词：铁铝酸钙 水化 钙矾石 动力学 模型 水泥 

分 类 号：TQ172.11[化学工程—水泥工业]