Study On Synthesis Of Functionally Inorganic Nanopowder By Vacuum Freeze-Drying

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...