Burn time of aluminum nanoparticles: Strong effect of the heating rate and melt-dispersion mechanism

A puzzling results were reported for burn time of Al nanoparticles at T=1100°C. At a heating rate of 103 C/s, the burn time exceeds 1 s [K. Park, D. Lee, A. Rai, D. Mukherjee, M. Zachariah, J. Phys. Chem. B 109 (2005) 7290–7299; M. Zachariah, private communication], while after fast heating (107 C/s), the burn time was only 500 μs [T. Bazyn, H. Krier, N. Glumac, Combust. Flame 145 (4) (2006) 703–713; T. Bazyn, H. Krier, N. Glumac, Proc. Combust. Inst. 31 (2007) 2021–2028]. This result is explained by the melt dispersion oxidation mechanism that operates for rapid heating only. Some characteristic parameters of this mechanism (critical heating rate, characteristic cluster size) are estimated.