超重力场中微细晶须碳酸钙结晶过程及产品稳定性研究

在旋转填充床转子高速旋转产生的超重力场中，以MgCl12或H3PO4为晶形控制剂合成微细晶须碳酸钙，通过反应过程中pH值的变化以及针状晶种存在与否两种情形下晶体形貌的演变对结晶过程进行了研究，同时对产品粒子的稳定性进行了初步探讨．结果表明，无晶种存在时，微细晶须碳酸钙晶形的形成需要经历不规则外形-类纺锤形-晶须状-微细晶须状4个阶段；有晶种存在时，产品粒子倾向于在其表面或周围成核，最终所有粒子短轴与长径比趋向均匀；微细晶须碳酸钙粒子在陈化及干燥情形下表现出良好的稳定性．

ON THE CRYSTAL PROCESS AND PRODUCT STABILITY OF THE ULTRAFINE CALCIUM CARBONATE WHISKERS IN HIGH-GRAVITY FIELD

The crystal process of the ultrafine whiskers of calcium carbonate, wh ich were successfully synthesized in high_gravity field generated by the rotatin g packed bed (RPB) in presence of MgCl 2 or H 3PO 4 used as the morphology_co ntrol additive, was studied through the change of pH and evolvement of crystal form du ring the crystallization under conditions of needle_like crystal seeds existing and not. Meanwhile, the stability of the product particles was discussed briefly . The results show that the formation of the crystal shape of ultrafine whiskers of calcium carbonate consists of four steps, which comes along with the anomalou s shape, spindle_like shape, whisker and ultra_fine whisker without crystal seed s. While the product particles tend to nucleate on the surface or near to the cr ystal seeds added into the solution ahead of time, and both the short shaft and the aspect ratio of the obtained particles trend are even. Besides, th e ultrafine whiskers of calcium carbonate show excellent form stability in the c ircumstances of aging or drying and disperse stability in the aqueous media.