Al ultra-fine grains are prepared by dry roller vibration milling at room temperature. After the ultrasonic hydrolyzing, the Al powders are milled for 2 h, 4 h and 8 h, separately, becoming the colloidal Al(OH)3. After the hydrolyzing production are dried, grinded, calcined, the flaky -Al2O3 nano-particles are obtained, and the particles sizes are in the range from 30 to 50 nm. By X ray diffraction (XRD) analysis method and transmission electron microscope (TEM), we analyze the energy conversion of solid particles in the vibration milling, and study the relation between the structure evolvement of solid particles and mechano-chemical reaction, in order to ascertain ideal milling time. The research results indicate that the solid particles under the action of mechanical force generate a mass of deformation and dislocation flaws and the material is in metastable high-energy state, which is favorable for inducing mechano-chemical reaction. In certain conditions, the surface energy of crystalloid, strain and dislocation energy could be mutually converted. The odds of lattice distortion and dislocation are maximal for the 2 h-milled Al powders, so the material shows a higher chemical reaction activation. On the ultrasonic agitation, the energy is fully released from the material interior, then Al(OH)3 nano-particles are prepared in a short time.
MgO nano-particles are prepared by ultrasonic cavitate, and-Fe2O3 nano-particles are prepared by chemical precipitation method, then MgO and-Fe2O3 are mixed in a beaker. After the ultrasonic dispersion for 2 h, MgO/-Fe2O3 admixture is calcined at 400℃ to synthesize MgFe2O4 nano-particles. TEM and XRD tests show that MgFe2O4 takes on a spinel structure and the particles sizes range from 20 to 30 nm. The theoretieal analysis indicates that the ultrasonic cavitate effect enhances the reaction activity of raw material, augmentes specific surface area and the contact area of reactant, which can promote reaction rate, reduce reaction temperature, and make possible the chemical reaction that is difficult to complete in common condition.
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