Investigation On Effects Of Environmental Factors On Activity Of Aluminum Nanoparticles

Aluminum (Al) nanoparticles were synthesized by hybrid laser-induction heating (HILH). Based on this raw material, several environmental factors on activity of Al nanoparticles were studied. Both the humidity controlling equipment and the apparatus for determining active Al were prepared. Effects of humidity on activity of Al nanoparticles were carefully discussed as well as that of environmental temperature and time. Environment humidity in the experiment was achieved by the use of two-temperature and saturated salt methods. Active Al was determined in terms of the gasometric and oxidation-reduction titration methods. The results indicated that activity of Al nanoparticles was deeply influenced by the environment humidity. The higher relative humidity would accelerate the aging of the Al nanoparticles. And enthalpy change was consistent with the value of active Al. It turned out that the enthalpy change and the value of active Al can be used as active criterion of Al nanoparticles. DSC-TG results showed that Al nanoparticles exhibited unusual thermal behavior, and the oxidation of Al nanoparticles occurs at least in two steps. HRTEM image revealed that there was a compact amorphous oxide layer with 3nm thickness coated on the original Al nanoparticles. After stored for 8 weeks, the oxide layer grew up to 5nm-thick and then virtually stopped. It were also founded that the oxidation diffused into the interior of Al nanoparticles and the oxidation phenomena along the boundary of grain. Those results could well explain the decrease of enthalpy change and content of active Al. In the end, the oxidation mechanism of Al nanoparticles was also discussed.