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Numerical Investigation on the Crucible Discharge of Steel and Slag During the Aluminothermic Welding Process

Weiss S., Riehl I., Hantusch J., Gross U.

Archives of Metallurgy and Materials

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2018

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Vol. 63, iss. 1

173--180

EN

The aluminothermic reaction is a type of self-propagating high-temperature synthesis to produce high quality metals and metal oxides en route. The main use of the aluminothermic reaction is in the field of railway welding. The multiphase flow of steel, slag and air in differently shaped crucibles has been numerically investigated in this work with the volume-of-fluid method. The simulations were carried out with the multiphase solver of the open source toolbox OpenFOAM. To validate the numerical results of the three-dimensional simulations, an experiment was carried out to investigate the discharge of a water-oil system from the crucible. A comparison to a numerical 3D simulation showed reasonable accurate results. It can be said that the solver is capable of predicting the point of the oil penetration of the water phase in the experiment.

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Nanoscale Aluminum - Metal Oxide (Thermite) Reactions for Application in Energetic Materials

Piercey D. G., Klapötke T. M.

Central European Journal of Energetic Materials

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2010

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Vol. 7, nr 2

115-129

EN

Energetic materials fnd use in both military and civilian applications, however many commonly used materials suffer from serious defciencies including toxicity and high sensitivity. Nanothermites exhibit vastly differing characteristics compared to their well known micron scale relatives and through the use of various preparatory chemical techniques can be tailored to have a wide spectra of chemical and energetic properties. This may allow use as superior replacements of conventional energetic materials in various applications.

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Mechanical Activation of Al/MoO3 Thermite as a Component of Energetic Condensed Systems to Increase Its Effciency

Meerov D., Ivanov D., Monogarov K., Muravyev N., Pivkina A., Frolov Y.

Central European Journal of Energetic Materials

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2009

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Vol. 6, nr 3-4

277-289

EN

In the present work a stoichiometric energetic compositions Al+MoO3 prepared by dry mixing and by reactive milling of micro-scale particles were investigated. Morphology, particle size and surface structure of produced powders were examined using scanning electron microscopy, atomic-force microscopy, laser diffractometry and BET analysis. DSC/TG data were processed to obtain kinetic mechanism of the reaction between Al and MoO3. The combustion rate of Al+MoO3 thermite mixture increases with pressure, reaching a maximum at ~10 atm, and then decreases with further pressure increase. The rise of combustion rate at the low range of pressure is associated with the rise in the extent of the vapour phase penetrating the pores of the pressed sample as the ambient pressure increases. However, at a higher pressure the gas formation is suppressed, and the melt formed in the combustion process can selectively wet the pores resulting in inhibition of reaction. Burning rates of mechanical activated system Al+MoO3 are two times higher then not-activated system at ambient pressure ~10 atm and 8 times higher at ~40 atm. In additional experiments, nano-scale MoO3 powder was prepared by evaporation with a subsequent condensation onto cooled plate in an inert-gas fow. Scanning electron microscopy showed that nano-MoO3 particles are absolutely spherical with mean diameter ~100 nm, and atomic-force microscopy 278 D. Meerov et al. reveals smaller particles with mean diameter ~5-30 nm. DSC/TG data showed that the nano-MoO3 starts to sublime earlier than micro MoO3. The use of nano-sized components could considerably increase the burning rates of energetic condensed systems, because of its large specifc surface, lower temperature of sublimation, and high reaction ability.