| Firstly this paper summarizes the current status of nano-material applications and opportunities opened by nanotechnology to many fields, such as new materials, environmental protection, energy, healthcare, IT and other traditional industries that need upgrade their products. The preparation of ultrafine alumina powder is of far reaching importance to the development of electronic and material industry .Hydrochemical preparation techniques are the important methods to make ultrafine powder of Al2O3 with its intrinsical advantage. It also summarizes the development of the current nanotechnology and nano-material characteries.Based cheap AlCl3·H2O as raw materials, used in organic polymer dispersed under anodizing process of alumina nanoparticles, and the basis of nano-Zinc Aluminum and Magnesium Aluminum composite oxides. Organic Synthesis alumina nano-technology is a simple, low cost, high purity, to mass production, the advantages of short process which is a great potential for the nano-powder preparation methods. The work studied the precursor reunion, and the particle size and morphology, by controlling the preparation conditions such as pH, temperature, dispersant, the degree of the dispersant, and the calcination temperatures. The preparation of such nano-alumina powders, seldom are reported in the literatures. The diameter , crystal type, morphology and the mechanism of dehydration of precursor were characterized by means of physical techniques, including XRD,TEM,FTIR and DTA measurement.The research shows that by adding polyethylene glycol as a dispersant can inhibit effectively agglomeration, and the degree of the dispersant is a major factor which can inhibit effectively agglomeration, It was found that the dispersants were matched with different degree played the most effective role of inhibiting agglomeration. The work shows that the calcination temperatures play a decisive role for the crystal style of the product, the higher calcination temperature and the more integrity crystal style, and the less volatile components. At 400℃, the characteristic peak ofγ-Al2O3 can be seen. And at 800℃, the product ofγ-Al2O3 which is a single component, small size, uniform distribution, specific surface area, pore volume, with activity and more integrity crystal style can be received, and at 1200℃the stable a-Al2O3 that was small size , more integrity crystal style was received . Through a lot of experiments, the optimized preparation of ultrafine alumina powders are as follows: Mediating alumina chloride solution using a certain concentration of NaOH until the pH value of 8. Filtering the sediment, and absorbing the solution , Matching the polyethylene glycol 400 and polyethylene glycol 10,000 by the ratio of 3 for a dispersant to the solution. With a strong stirring and the temperature of water bath was maintained at 45℃.The ultrafine alumina powders of small particle size and uniform distribution was obtained.The major work as follow:(1) Study the condition of preparing ultrafine alumina powders. Through a lot of experiments, the major factors of the reaction were identified, including the pH value, the reaction temperature, dispersant, the degree of dispersant and the calcination temperature.(2)Analyzing the alumina powder by the FTIR, as well as aluminum hydroxide precursor was analyzed by DTA which can show phase change and the mechanism of dehydration of aluminum hydroxide precursor.(3)On the basis of the successful preparation of nanometer alumina powders, the Zn-Al, Mg-Al composite were prepared by adding the solution of ZnCl2.and MgCl2 The diameter of the powders is small, the average size is about 20 nm, the crystal style is integrity, and the morphology is spherical fiber. The Zn-Al, Mg-Al composite oxides can be prepared by calcining the precursor at 400℃, 3h. |
