柠檬酸对二水石膏晶体生长习性与晶体形貌的影响  

Effect of critic acid on crystalline habit and crystal morphology of dihydrate

作　　者：彭家惠[1] 瞿金东[1] 吴莉[1] 张建新[1] 

机构地区：[1]重庆大学建筑材料工程系,重庆400045

出　　处：《东南大学学报（自然科学版）》2004年第3期356-360,共5页Journal of Southeast University：Natural Science Edition

基　　金：国家自然科学基金资助项目 (5 0 0 780 5 5 )

摘　　要：利用扫描电镜 (SEM)、X射线光电子能谱 (XPS)等测试手段分析了柠檬酸对二水石膏晶体结晶习性的影响 ,并从晶体生长的角度揭示了柠檬酸的缓凝机理 .结果表明 :柠檬酸由于能与钙离子发生络合作用 ,降低了钙离子在各个晶面上的叠合速率 ,从而减缓了石膏晶体的生长速率 ,晶体粗化 ;柠檬酸优先吸附在生长最快的c轴方向上 ,抑制c轴的生长 ,从而改变各个晶面的相对生长速率 ,晶形由针状变为短柱状 ;加入柠檬酸后 ,建筑石膏的缓凝、石膏硬化体强度的下降均与二水石膏晶体生长习性的改变息息相关 .By use of scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS),effect of critic acid on crystalline habit of dihydrate was analyzed,and retarding mechanism of critic acid was also discussed from the standpoint of crystal growth. The results show that due to the complexion between critic acid and Ca 2+ the bonding rate of Ca 2+ on various crystal face is greatly decreased,correspondingly,the growth rate of dihydrate crystal is slowed down,as a result,the size of crystal becomes much larger in presence of critic acid. Critic acid is preferably adsorbed on c-axis which usually has the fastest growth rate,and hinders its growth. Therefore critic acid varies the relative growth rate of various crystal faces,which consequently leads to the transformation of dihydrate crystal from needle-like to short prismatic. After the addition of critic acid, the retarding effect produced and the strength reduction of hardened gypsum paste are closely related to the variation of crystallization habit and crystal structure of hydration products.

关 键 词：石膏 柠檬酸 晶体形貌 生长习性 

分 类 号：TQ177.32[化学工程—硅酸盐工业]