Research On Hydrothermal-Based Route To Nano Alumina Powders And Morphology

Alumina was well known as the main component of the ruby and sapphirematerials with high elastic modulus, high thermal and chemical stability. Withthe development of nanotechnology, people have a better understanding ofnano-alumina to find that nano-alumina has a large specific surface area, strongabsorption of light, low melting point, low chemical activity and othercharacteristics. So it was widely applied in aerospace, medical, microelectronicsmaterials and other fields. As the ceramic materials, it can effectively reduce thesintering temperature and significantly improve the flexural compressivestrength and fracture toughness because of the small particle size. As a catalystand catalyst carrier, nano-alumina has large specific surface and high chemicalactivity that can generate active point with the surface breaking chemical bondsand mismatch key. As optical materials, nano-alumina with a single dispersioncan be made into the substrate of the integrated scale circuits; as biomaterials,nano-alumina can be used to alternate human teeth and bones materials.With such excellent performance, so it is needed to find a simple andefficient method to prepare the high-quality nano-alumina materials.Nano-alumina is not easy to prepare because of agglomeration. So the main pointis to prepare the boehmite （γ-AlOOH） which is the precursor for the preparationof nano-alumina materials. In this paper, the hydrothermal method was used byadding a variety of surfactants to prepare different size and morphologies ofboehmite （γ-AlOOH）. The physicochemical properties of these materials werecharacterized by means of the techniques, such as scanning electron microscopy（SEM）, transmission electron microscopy （TEM）, selected area electrondiffraction （SAED）, X-ray diffraction （XRD）, Fourier transform infraredspectrum analyzer （FTIR）, UV-Vis diffuse reflectance spectroscopy （UV-vis） andother testing methods to study the relationship between powder morphology andproperties. The results are as follows:Different size of γ-AlOOH nanofibers were prepared by adding different Na sources （sodium tungstate, sodium acetate, sodium alginate, sodium silicate）with AlCl₃·6H₂O as the Al sources.The influence of different content of template and hydrothermal time for thephases and morphology were researched by adding sodium carboxymethylcellulose for template.Research and explore the γ-AlOOH nanowire growth mechanism. Inaddition, we used the aluminum isopropoxide as aluminum source and themicrowave hydrothermal microwave hydrothermal reaction was kept at160℃for90minutes, after calcining the preparation of nano-alumina powder. Theinfluences of different calcinations temperature, content of lauric acid and nitricacid for the morphology of nano-alumina powder were researched.