Characterizing the energy transfer from a thermite reaction to a target



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Nano-sized materials often have novel properties that drastically improve performance. Very few studies on the nano-aluminum and water combustion reaction have been done without the addition of a gelling agent. The depth at which gas fueled underwater cutting torches can be used is limited by their fuel gas storage pressure restrictions. Using a nano-aluminum and water thermite reaction as the fuel for an underwater cutting torch eliminates depth limitations and creates a unique opportunity to use ambient water from the surrounding environment as the oxidizer for the reaction. Reaction characteristics were studied with high speed video analysis in inert and oxidizing environments. The heat transfer characteristics of the nano-aluminum and water reaction were compared to baseline methylacetylene-propadiene and propane fueled torches by collecting temperature data on metal test plates with thermocouples and a high speed infrared camera. Additives, such as Teflon powder, were mixed with the original thermite reactants to improve heat transfer to the test plates from the reaction.

High speed video data showed that flame propagation rates were not significantly affected by the environment surrounding the reaction. Differential scanning calorimeter data confirmed that the aluminum was reacting efficiently. Temperature data from the test plates was compared after 0.9 s of heating. Thermocouple data confirms infrared camera temperature measurements. The MAPP gas torch, propane torch, Al/water reaction, and Al/water/Teflon reaction heated the plates at an average rate of 29.3 ± 0.2, 23.1 ± 0.2, 54 ± 3, and 38 ± 1 K/s respectively. The temperature change per mass of fuel burned was calculated for each torch and reaction as 400 ± 200, 500 ± 200, 180 ± 60, and 130 ± 30 K/g respectively. The time required to reach the oxidation temperature of steel for each torch and reaction was 40 ± 20, 50 ± 30, 21 ± 9, and 30 ± 10 seconds respectively. This study concludes that the Al/water reaction could significantly improve an underwater cutting device because surrounding water could be used as the primary oxidizer, the reaction has a higher heating rate than gas fuels, and the usable depth is not limited by fuel storage pressures.