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Thesis Advisor毛铭华
Degree Grantor中国科学院研究生院
Abstract本工作探索了水热脱水法制备超细氧化锆粉末的工艺条件,实验结果表明,水合氧化锆浆料在190 ~ 250 ℃范围内脱水能直接形成无水的超细氧化锆粉末,而不需要再经过高温煅烧,所得粉末的平均粒径为80nm,并且具有很小的团聚参数。本工作还对影响脱水程度、颗粒大小及粉末晶型的因素作了研究。实验认为,当水合氧化锆完全脱水时,脱水温度和时间可按下式表示:t = 2.8148 * 10~(-5)exp(6278/T) 从而提出了水热脱水的工艺条件为:温度210 ℃,时间2小时;粉末的晶型与沉淀时的pH值有关,它只取决于脱水前水合氧化锆的形态,而与脱水条件无关;实验还认为,沉淀时的pH值、硫酸锆溶液的浓度及沉淀浆料的浓度对粉末团聚状态都有一定的影响,如果在沉淀初期引进具有静电效应或位阻效应的表面活性剂,抽滤时考虑到用表面张力较低的乙醇置换水,能获得基本上无团聚的氧化锆粉末,从而有效地提高了粉末的性能。本实验还提出了一个全水热法制备超细氧化锆粉末材料的工艺流程。
Other AbstractA hydrothermal method for producing ultrafine zirconia powder which could be used in fine ceramics has been developed. An aqueous slurry of hydrous zirconia prepared by adding an aqueous alkali to the solution of zircon salt is dehydrated at 190 ~ 250 ℃ to form the ultrafine zirconia powder. The process may produce anhydrous powder directly and high temperature calcination is not required to convert hydroxide to oxide as it is in most other methods. The powder obtained has an average diameter of 80nm with minimal agglomeration. In this work the factors which influenced the rate and degree of dehydration of hydrous zirconia, the particle size and the crystal structure have been studied. The relation between temperature and duration of dehydration can be expressed as: t = 2.8148 * 10~(-5)exp(6278/T) The crystal structure of ZrO_2 powder is determined by the pH value of the precipitation and has no relation to the hydrothermal conditions. The agglomeration state of ZrO_2 powder is influenced by the pH value of the precipitation, the concentration of zircon sulphate solution and the content of hydrous zirconia in the slurry, and can be improved efficiently by adding a small amount of surfactants and washing the product with alcohol during filtration. A flow sheet for the preparation of ultrafine ZrO_2 powder by hydrothermal method has been suggested.
Document Type学位论文
Recommended Citation
GB/T 7714
马剑华. 水热法制备超细氧化锆粉末的研究[D]. 中国科学院研究生院,1991.
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