Preparation And Characterization Of The Sol Precursor Nano-structured Fiber Material

In the chapter one of this thesis, first, the phylogeny of sol-gel process was introduced briefly. Then, the principle of the chemistry of sol-gel was introduced. The procedures involved in sol-gel process including the hydrolysis and polycondensation of the metal alkoxide, gelation, aging, drying and heat treatment were recommended in details. A great deal of attentions had been paid for the influence of the processing parameters on every step, and the corresponding characterization techniques were given. Whereafter, the application of sol-gel process in the preparation of metal oxide ceramic fibers was reviewed.Afterwards, the definition of nanofibers category and the applications of electronic injection technique are firstly introduced. Secondly, the theory of the utilizing of electronic injection technique for preparation of fibers and the two different points on the results of the fibers obtained using this technique are discussed. Various factors that affect the fibers in the preparation process are also analyzed. In the preparation of nanofibers by electronic injection technique, a sol-gel process is usually employed to get a organic-inorganic-hybrid solution, then the solution is electronic injected to obtain the fibers. After calcinations at high temperature the inorganic nanofibers are finally obtained. Because of their small diameters and good surface state, the as-synthesized nanofibers possess great applications, such as structure strengthening, anti-water, insecticide, and so on.In chapter two, BaTiO₃ ceramic fibers were prepared by the sol-gel method related the spinning process in which catechol-complexed titanium isopropoxide and barium acetate hydrate were used as starting materials. The green fibers of ca.30cm in length were obtained from the precursor sols. The BaTiO₃ ceramic fibers with the average length of ca. 20cm were of the order of 1 to 5um in diameter and elliptical shapes in cross section. In addition, a small amount of hollow BaTiO₃ ceramic fibers were also observed and the possible formation mechanism was proposed. The green fibers and those sintered at different temperatures were characterized by TGA/DSC,...