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Size Resolved High Temperature Oxidation Kinetics of Nano-Sized Titanium and Zirconium Particles
journal contribution
posted on 2015-06-18, 00:00 authored by Yichen Zong, Rohit J. Jacob, Shuiqing Li, Michael R. ZachariahWhile
ultrafine metal particles offer the possibility of very high
energy density fuels, there is considerable uncertainty in the mechanism
by which metal nanoparticles burn, and few studies that have examined
the size dependence to their kinetics at the nanoscale. In this work
we quantify the size dependence to the burning rate of titanium and
zirconium nanoparticles. Nanoparticles in the range of 20–150
nm were produced via pulsed laser ablation, and then in-flight size-selected
using differential electrical mobility. The size-selected oxide free
metal particles were directly injected into the post flame region
of a laminar flame to create a high temperature (1700–2500
K) oxidizing environment. The reaction was monitored using high-speed
videography by tracking the emission from individual nanoparticles.
We find that sintering occurs prior to significant reaction, and that
once sintering is accounted for, the rate of combustion follows a
near nearly (diameter)1 power-law dependence.
Additionally, Arrhenius parameters for the combustion of these nanoparticles
were evaluated by measuring the burn times at different ambient temperatures.
The optical emission from combustion was also used to model the oxidation
process, which we find can be reasonably described with a kinetically
controlled shrinking core model.