【作者】 刘军；

【导师】 徐成海；

【作者基本信息】 东北大学 ， 流体机械及工程， 2006， 博士

【摘要】 真空冷冻干燥法制备纳米粉体是当今材料科学领域的前沿性课题之一，因其所制得的粉体具有微粒形状规则、粒径小而均匀、粒度分布窄、化学成分纯、粒子间无硬团聚、分散性好等特点，而受到关注。无机功能纳米粉体材料具有优秀的物理、化学等方面的特殊功能，作为高技术、高性能、高产值、高效益产品，而成为众多科研人员竞相研究开发的对象。所以本文选择采用真空冷冻干燥法制备无机功能纳米粉体作为研究主题。 本文以制备高品质无机功能纳米粉体为目标，从理论和实验两方面开展了溶液冷冻干燥法制备纳米粉体技术研究。文中对溶液冷冻干燥制备纳米粉体的重要步骤：前驱体溶液制取、溶液冻结和冻结物冷冻干燥进行了实验探索和详细的理论分析。 文中总结了溶液冷冻干燥法制备纳米粉体所使用的前驱体应具有的性能，从保证所制备粉体的品质、降低成本以及防止产生污染等角度出发，为所制备的氧化铝、氢氧化镍、氢氧化铜、氧化铜和银纳米粉体确定了理想的前驱体，并对以氨络合物为前驱体制备纳米粉体的所需工艺条件进行了理论计算和实验验证。文中还通过实验摸索出用于冷冻干燥制备纳米粉体的合适的前驱体溶液浓度，进而提出了选择前驱体的原则。 文中选择次醋酸铝和金属氨络合物为前驱体，采用冷冻干燥法制备出了氧化铝、氢氧化镍、氢氧化铜、氧化铜和银等无机功能纳米粉体材料，给出了制备粉体的具体操作方法、工艺参数和制备过程中涉及到的化学反应原理。 对所制备的各种粉体进行了X射线衍射分析、X射线能谱分析、差热和热重分析以及电镜观察等性能检测，对银纳米粉体还进行了细菌灭活实验检测。结果表明：所制备的粉体是颗粒细小、粒径均匀、团聚少、化学成分准确而纯净的纳米级粉体。 在实验中采用了适合于制备纳米粉体的前驱体溶液冻结的三种冷冻方式，即直接冷冻、真空蒸发冷冻和喷雾冷冻。结合实验结果，讨论了前驱体溶液浓度、三种冻结方式等工艺条件对所制备粉体的颗粒尺度与分散程度等品质的影响。实验发现，冷冻干燥法所制备的纳米粉体都是非晶体。 在实验研究的基础上，深入分析了溶液冻结阶段和冷冻干燥阶段的相变热力学过程与相变机制；针对溶质离析问题开展了传质理论研究，提出溶液冻结速率是影响造粒过程的最主要因素；依据热质传递理论，对三种冷冻方式分别建立了数学模型，求解得到了冰界移动速率、完成冻结所需时间等重要工艺数据；确定了溶质不离析的条件是：冰界面移动速率大于溶质的临界扩散速率，计算得到了直接冷冻方式保证溶质不离析的溶更多还原

【Abstract】 Synthesis of nanopowder by fireeze-drying is one of the hot and forward position subject in material science field because the powder synthesized by this method has many excellent characteristics such as regular particle shape, shall and even diameter, narrow granularity distributing, pure chemical composition, weak agglomeration, easy dispersal and so on. Functionally inorganic nanometer materials are focused on since their particularly function in physics and chemistry. Therefore, the synthesis of functionally inorganic nanopowder by freeze-drying is chose as the research subject in this thesis.In order to obtain the functionally inorganic nanopowder with high property, the nanopowder synthesis technology by solution freeze-drying are studied in theory and experiments. The 3 most important steps in nanopowder synthesis process, i.e., precursor solution preparation, solution freezing and its freeze-drying, are studied in detail.The property requirements for precursor solution used in nanopowder synthesis by freeze-drying are concluded. For the purpose of high properties, low price and low pollution, the ideal precursor solutions are chose for synthesizing alumina, nickel hydrate, copper hydrate, copper oxide and silver nanopowders. The process conditions needed for using ammonia complex compounds as precursor solution to synthesize powder of nickel hydrate and so on are given by theoretical calculation and experimental test. The suitable concentration and choosing principle of precursor solution are suggested.Taking basic aluminium acetate and metal ammonia complex compounds as precursor solution, the functional inorganic nanopowder of alumina, nickel hydrate, copper hydrate, copper oxide and silver, are successfully synthesized by freeze-drying. The operation method, process parameters and chemical reaction principle are given in concrete.All powders synthesized are detected by XRD, EDS, TEM and SEM. DTA and TG test are done for nickel hydrate and copper hydrate nanopowder to confirm their compounds. A bacteriostatic test is specially done for silver. The result shows that the powder synthesized are composed of small & even diameter, week agglomeration, pure chemical composition particles.Three kink of freezing styles of precursor solution - direct freezing, spray freezing and vacuum evaporation freezing - are used in the synthesis experiment. The influence of precursor solution concentration and freezing process parameters upon powder properties, such as particle size and dispersion degree, is discussed. It is found in experiments that all更多还原