【作者】 王觅堂；

【导师】 郝茂荣； 李梅； 柳召刚；

【作者基本信息】 内蒙古科技大学 ， 材料学， 2008， 硕士

【摘要】 本文采用连续沉淀法制备纳米氧化铈的前驱体——草酸铈粉体材料,研究内容主要分为三大部分:第一部分主要为沉淀过程中的操作条件对于结晶动力学相关参数的影响;第二部分主要为成核与生长阶段过程中不同的成核与生长环境条件对于一次粒径、团聚程度以及最终团聚体大小的影响;第三部分主要为大颗粒草酸铈的研究及团聚体尺寸模型的推导。结晶动力学的研究过程中主要研究了以稀土硝酸盐为原料、草酸为沉淀剂制备草酸铈前驱体的操作条件如,加料位置、搅拌速度、料液滴加速度和反应物浓度等对结晶过程中的成核速率与生长速率的影响,研究了前驱体的结晶动力学模型,并且按照经验方程通过对实验数据的拟合分别得到了成核速率和生长速率与溶液过饱和度的经验方程: B = 3. 01×10⁸ΔC^1.65, R 2 =0.91; G = 5 .17×10^-6ΔC^1.82, R 2 =0.97。根据结晶动力学的研究结果,首先将整个沉淀过程从时间与空间上划分为成核（主要发生成核以及一定程度的生长）与生长（主要进行生长和团聚过程,没有成核发生）两个阶段。在成核阶段主要研究了不同的工艺条件对于成核器出口粒径以及成核过程中团聚程度的影响,确定了成核阶段的最佳条件。在生长阶段主要研究了不同的生长环境条件如搅拌速度、生长温度、PH值、电解质浓度、分散剂浓度等对于最终产物团聚体的影响。按照结晶动力学的研究结果,对大颗粒草酸铈的制备进行了研究。同时在研究团聚的过程中,建立了比功率、过饱和比和团聚体尺寸的模型如下:将该模型一般化为:更多还原

【Abstract】 In this paper, the precursor of CeO2 powders—Ce2（C2O4）3 was prepared by continuous precipitation method with cerium nitrate and oxalate as raw materials and precipitator respectively. The study includes mainly three parts: the first part is that the effect of operational conditions on correlation parameter of crystallization kinetics; the second part is that the effect of the different conditions of nucleation and growth process on the grain size, degree of agglomeration and particle size; the third mainly study on the preparation of large particle and mathematical model.In the study on correlation parameter of crystallization process, the influence of operational parameters such as feed position, micro-mixing efficiency, feeding speed and reactant concentration on nucleation velocity and growth rate was studied. Nucleation velocity and growth rate were respectively obtained by fitting experimental data according to empirical formula as follows: B = 3. 01×10⁸ΔC^1.65, R 2 =0.91; G = 5 .17×10^-6ΔC^1.82, R 2 =0.97。The process of precipitation was divided two processes: nucleation （nucleation take place mainly in this step, also partial growth） and growth process （there is mainly growth and agglomeration without nucleation）. The effect of conditions of the precipitation on particles size of crystallizer and content of agglomeration was investigated in the nucleation process and optimum operational conditions of nucleation were obtained. The influence of different growth environment namely agitation speed, growth temperature, PH, electrolyte and dispersant （PEG1000） concentration on final agglomerates size was studied. The preparation of large particle Ce2（C2O4）3 was studied according to result of crystallization kinetics. In the study of agglomeration the relationship of particle size with specific power input and super saturation was obtained as follows: This relationship was generalized as follows:更多还原