沉淀法制备高比表面超细氧化锆过程结晶动力学

发布时间：2018-03-22 09:30

本文选题：沉淀法　切入点：动力学　出处：《无机盐工业》2017年11期 　论文类型：期刊论文

【摘要】：在前期研究工作中,以氧氯化锆溶液为前驱体,一定量的PEG-600为分散剂,氨水为沉淀剂,通过化学沉淀法合成Zr(OH)_4沉淀。经后续洗涤、过滤、干燥和焙烧成功制得了高比表面超细ZrO_2粉体材料。为了研究Zr(OH)_4沉淀过程的成核机理,设计了动力学实验。配制一定浓度的氧氯化锆溶液和氨水,迅速混合后得到Zr(OH)_4过饱和溶液,用电导率仪在线测定Zr(OH)_4过饱和溶液在沉淀过程中电导率随时间的变化,以此反映溶液中离子浓度的变化。将Zr(OH)_4沉淀成核及晶体生长过程看成一级反应,通过数据拟合可得出Zr(OH)_4沉淀成核及晶体生长过程的速率常数。结果发现:其成核速率k_1远大于生长速率k_2,混合瞬间爆发成核,避免二次成核造成的晶粒长大,说明该工艺适合制备高比表面超细ZrO_2粉体。
[Abstract]:In the previous research work, Zr(OH)_4 precipitation was synthesized by chemical precipitation with zirconium oxychloride solution as precursor, a certain amount of PEG-600 as dispersant and ammonia water as precipitant. Ultrafine ZrO_2 powder with high specific surface was prepared successfully by drying and roasting. In order to study the nucleation mechanism of Zr(OH)_4 precipitation, kinetic experiments were designed. The supersaturated Zr(OH)_4 solution was obtained by mixing zirconium oxychloride solution and ammonia water with a certain concentration. The change of conductivity of supersaturated Zr(OH)_4 solution with time during precipitation is measured online by conductivity meter, which reflects the change of ion concentration in solution. The nucleation and crystal growth of Zr(OH)_4 precipitation are regarded as first-order reactions. The rate constants of Zr(OH)_4 precipitation nucleation and crystal growth process can be obtained by data fitting. The results show that the nucleation rate of Zr(OH)_4 is much higher than that of growth rate KSP 2, and the mixed nucleation occurs instantly to avoid the grain growth caused by secondary nucleation. It shows that this process is suitable for the preparation of ultrafine ZrO_2 powders with high specific surface.
【作者单位】：大连理工大学化工与环境生命学部化工学院;内蒙古科技大学化学与化工学院;
【基金】：内蒙古自然科学基金(2017MS0219、2016MS0514) 国家自然科学基金(21466029)
【分类号】：TQ134.12

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