Thursday, April 10, 2014

A 2004 paper reveals a nanothermite material that ignites at 410C

A 2004 paper on iron-oxide/aluminum nanothermite by Dr. Menon et al. called Ignition studies of Al/Fe2O3 energetic nanocomposites is interesting for a couple of reasons. The abstract states that:
"We prepare energetic nanocomposites, which undergo an exothermic reaction when ignited at moderate temperature. The nanocomposites are a mixture of Al fuel and Fe2O3 oxidizer where Fe2O3 is in the form of an array of nanowires embedded in the thin Al film. We achieve a very high packing density of the nanocomposites, precise control of oxidizer–fuel sizes at the nanoscale level, and direct contact between oxidizer and fuel. We find that the flame temperature does not depend on ignition temperature."
In fact, the "moderate" ignition point is as low as 410C, depending on method, which is very close to the 420C observed by Dr. Harrit et al.. Some "debunkers" have argued that 420C is too low to be consistent with a Fe2O3/Al nanothermite, but they refuse to acknowledge that it is easy to tune the performance via different morphologies of the ingredients. Dr. Menon´s material is based on a "thin Al film" while Harrit´s material had thin Al nano-platelets, and this may explain the low ignition temperatures. Dr. Menon has confirmed that the material was ignited in air, and this may explain the extremely robust flame temperature of 4000C.