CAS OpenIR  > 研究所(批量导入)
Thesis Advisor毛铭华
Degree Grantor中国科学院研究生院
Abstract本工作对水热法分解锆英石制备超细二氧化锆粉末材料过程进行了物理化学方面的研究。重点考察锆英石的水热分解过程,选择了一个最佳的水热分解体系,即NaOH体系;讨论了温度、搅拌速度、碱浓度、反应物粒度以及液固比对NaOH体系锆英石水热分解的影响,获得了最佳的水热分解条件(分解率可达99%以上);提出了NaOH体系中锆英石水热分解的机理,对水热分解产物进行水热脱水处理以制得超细的二氧化锆粉末材料作了一定的探讨,并获得了0.01μ的超细二氧化锆粉末,同时提出了一个由锆英石制备超细二氧化锆粉末的建议流程。研究结果表明:锆英石在NaOH体系中水热分解的产物为Na_2ZrSiO_5。水热分解反应为生成产物层内扩散控制的液固相非催化反应,反应的表观活化能为37.65kcal/mol。反应的宏观速率方程为1-2/3·α-(1-α)~(2/3)=3.975 * 10~7·A~(2.164)·C~(1.425)·e~(-18950/T)·t反应机理可设想为:(1)流体反应物NaOH由液相主体通过固体ZrSiO_4颗粒外表面的液膜扩散到颗粒外表面;(2)流体反应物NaOH由颗粒外表面通过固体产物层扩散到收缩未反应芯ZrSiO_4的界面上;(3)流体反应物NaOH与固体反应物ZrSiO_4在界面上进行化学反应。其中(2)为控制步骤。
Other AbstractThe physico-chemical aspects of hydrothermal decomposition of zircon have been studied. It was found that the NaOH is the efficient reagent for decomposition of zircon. Under the optimum conditions, above 99% of zircon can be decomposed. The effects of various reaction conditions such as temperature, concentration of alkali, solid/liquid ratio, particle size, stirring rate on the decomposition rate are investigated in detail, and rational operation conditions for decomposition have been given in this thesis. The results show that the hydrothermal decomposition reaction ZrSiO_4+2NaOH = Na_2ZrSiO_5+H_2O is a diffusion-controlled, non-catalytical, solid-liquid reaction. The apparent activation energy is found to be 37.65 kcal/mol. The rate equation may be written as 1-2/3·α-(1-α)~(2/3) = 3.975 * 10~7·A~(2.164)·C~(1.425)·e~(-18950/T)·t. The reaction mechanism consisting of the following sequence of steps has been proposed: (1) Diffusion of NaOH in the solution. (2) Diffusion of NaOH through the solid product layer Na_2ZrSiO_5. (3) Chemical reaction on the surface. Step (2) is the rate-controlling step. Based on the experimental data a flow diagram of preparation of ultrafine ZrO_2 powders from zircon by hydrothermal reaction method has been suggested. Ultrafine ZrO_2 powders with d~0.01μ can be obtained.
Document Type学位论文
Recommended Citation
GB/T 7714
殷澍. 水热分解锆英石的物理化学研究[D]. 中国科学院研究生院,1990.
Files in This Item:
File Name/Size DocType Version Access License
水热分解锆英石的物理化学研究.pdf(2487KB) 限制开放CC BY-NC-SAApplication Full Text
Related Services
Recommend this item
Usage statistics
Export to Endnote
Google Scholar
Similar articles in Google Scholar
[殷澍]'s Articles
Baidu academic
Similar articles in Baidu academic
[殷澍]'s Articles
Bing Scholar
Similar articles in Bing Scholar
[殷澍]'s Articles
Terms of Use
No data!
Social Bookmark/Share
All comments (0)
No comment.

Items in the repository are protected by copyright, with all rights reserved, unless otherwise indicated.