Preparation of Aluminum Nanoparticles and Oxidation Mechanism of Nano- and Micro-Particles

Aluminum nanoparticles were prepared by laser and inducting heating methods, then the phase, structure and thermal properties of them were characterized by X-ray diffraction, electron microscope and simultaneous thermal analyzer, respectively. The results showed that there was great difference between micro- and nanoparticles in oxidation behavior. Aluminum micron particles had a very strong endothermic peak at the temperature of about 660 degrees C and the absorption heat enthalpy is 328J/g.The release heat enthalpies of aluminum nanoparticles oxidized by oxygen are 4.219 kJ/g and 3.584 kJ/g. Because of the size decreases to nano-size, the aluminum nanoparticles can be oxidized directly by oxygen and release a large amount of heat, which is beneficial to the propellants when it been burn. However, the micro-particles should absorb heat which other components released, and release heat slowly after melted, which are not as good as the nano-ones.