Nano-Al and Nano-Al/CuO Thermite Under Rapid Heating: A Mechanistic Study

The aluminum nanoparticles (Al-NPs) and nano-Al/CuO thermite mixture were investigated in a rapid heating environment  by temperature jump time-of-flight mass spectrometry. Upon rapid heating (10⁵ K/s-10⁶ K/s) of Al-NPs in vacuum, Al species intensity was found to slowly increase until a sudden increase occurs at ~2030 K, suggesting an enhancement of the outward diffusion of Al species which is consistent with the diffusion based mechanism. Presence of hollow particles after Al-NPs heated to 1650 K also reveals the diffusion of Al through the oxide shell. The lack of mass production of Al-containing species below 2030 K indicates the oxide shell prevents the mass ejection of Al-containing species from the aluminum core. Time resolved mass spectra of nano-Al/CuO reactions show the existence of Al, Al₂O, AlO and Al₂O₂ intermediate reaction products, and the Al₂O specie was found to be the main intermediate oxidation product which agrees with the thermochemical calculation results.