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。
Zr（OH）4 precipitate was prepared by chemical precipitation method with zirconium oxychloride solution as pre-cursors ,PEG-600 as dispersant and ammonia as precipitating agent in the previous work.The ultrafine ZrO2 powder with high specific surface was successfully prepared by subsequent washing,filtration,drying,and roasting.In order to study the nuclea- tion mechanism of Zr（OH）4 precipitation process, the kinetic experiment was designed.The supersaturated Zr（OH）4 solution was prepared by rapid mixing of zirconium oxychloride solution and ammonia solution.The conductivity of supersaturated Zr（OH）4 solution was measured on-line during the precipitation process with the conductivity meter to reflect the ion concen-tration in the solution.The rate constants of the nucleation and crystal growth of Zr（OH）4 can be obtained by fitting the data of Zr（OH）4 precipitation,nucleation and crystal growth process as a first-order reaction.The results showed that the nucleation rate k 1 was much larger than the growth rate k2,and the nucleation of the mixture occurred at the moment,so that the grain growth caused by secondary nucleation was avoided.The results showed that this method was suitable for the preparation of ultrafine ZrO2 powders with high specific surface area.
出处
《无机盐工业》
CAS
北大核心
2017年第11期33-36,共4页
Inorganic Chemicals Industry
基金
内蒙古自然科学基金(2017MS0219
2016MS0514)
国家自然科学基金(21466029)
关键词
沉淀法
动力学
二氧化锆
电导率
结晶
precipitation method
kinetics
zirconium dioxide
conductivity
crystallization
