Effect of heating rates on TG-DTA results of aluminum nanopowders prepared by laser heating evaporation

Aluminum (Al) nanopowders with mean diameter of about 50 nm and passivated by alumina (Al2O3) coatings were prepared by an evaporation route: laser heating evaporation. Thermal properties of the nanopowders were investigated by simultaneous thermogravimetric-differential thermal analysis (TG-DTA) in dry oxygen environment, using a series of heating rates (5, 10, 20, 30, 50 and 90A degrees C min(-1)) from room temperature to 1200A degrees C. With the heating rates rise, the onset and peak temperatures of the oxidation rise, and the conversion degree of Al to Al2O3 varies. However, the specific heat release keeps relatively invariant and has an average value of 18.1 kJ g(-1). So the specific heat release is the intrinsic characteristic of Al nanopowders, which can represent the ability of energy release.