A Benchmark Study of Burning Rate of Selected Thermites through an Original Gasless Theoretical Model

Abstract

This paper describes a kinetic model dedicated to thermite nanopowder combustion, in which core equations are based on condensed phase mechanisms only. We explore all combinations of fuels/oxidizers, namely Al, Zr, B/CuO, Fe2O3, WO3, and Pb3O4, with 60 % of the theoretical maximum density packing, at which condensed phase mechanisms govern the reaction. Aluminothermites offer the best performances, with initiation delays in the range of a few tens of microseconds, and faster burn rates (60 cm s−1 for CuO). B and Zr based thermites are primarily limited by diffusion characteristics in their oxides that are more stringent than the common Al2O3 barrier layer. Combination of a poor thermal conductivity and efficient oxygen diffusion towards the fuel allows rapid initiation, while thermal conductivity is essential to increase the burn rate, as evidenced from iron oxide giving the fastest burn rates of all B- and Zr-based thermites (16 and 32 cm·s−1, respectively) despite poor mass transport properties in the condensed phase; almost at the level of Al/CuO (41 versus 61 cm·s−1). Finally, formulations of the effective thermal conduction coefficient are provided, from pure bulk, to nanoparticular structured material, giving light to the effects of the microstructure and its size distribution on thermite performances.

Some Aspects of the Burning Process of Antimony and Potassium Manganate(VII) Compositions

“…The above analysis shows that the only way to determine the heat of combustion for Sb/KMnO 4 compositions are calorimetric measurements in an inert gas. The heat determined in this way can be used in modeling the combustion process of these compositions, for example, with the use of models [ 13 , 14 , 15 ].…”

Hot Bridge-Wire Ignition of Nanocomposite Aluminum Thermite Synthesized Using Sol-Gel-Derived Aerogel with Tailored Properties for Enhanced Reactivity and Reduced Sensitivity

“…The charging pressure, denoting the initial pressure at which the mixture is introduced into the explosion tube prior to initiation, emerges as a paramount factor that exerts influence on the characteristics of initiation and shock wave propagation within these tubes. Meticulous control and monitoring of this charging pressure are imperative to ensure consistency and precision in experimental setups involving explosion tube configurations [133][134][135][136][137].…”

Experimental evaluation of aluminothermic welds

“…The shape of the mould is determined by the dimensions of the profiles to be joined. Thus, the slag and corundum can be cast by overflowing outside the mould into the prepared cup, to eliminate the mixture with the weld metal (the process is described more in [11]). In cooperation with the company Pandrol Ltd. (training centre in Kralupy nad Vltavou), the welding process of two different types of profiles (HEB140 and 60E2) were experimentally investigated.…”