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SHS Welding
Refractory Single Crystal Growth
Electro Thermal Explosion

Electro Thermal Explosion

ElectroThermal Explosion (ETE) is practically unique experimental method, enabling to investigate a mechanism and a kinetic of high-temperature high-speed exothermic reactions in heterogeneous condensed systems, at temperatures up to 4000 K with characteristic conversion times less than 1 ms. In the basis ETE is heating of reactable sample by direct passing of an electrical current through it with instant interruption of an electric heating at the moment of a self-ignition begins and the optical registration in a time of sample surface temperature. The adiabatic self-heating of a sample provides a space uniformity passing of the reaction and enables with quantitative completeness to calculate the kinetic parameters from an experimental thermograms.

Technique

The ElectroThermal Explosion method permits to raise the top temperature border up to significances of the order 4000 K and to register speed of reactions with characteristic conversion times up to 0.1 ms, i.e. to study of the kinetic in all temperature-time interval, presenting interest for theoretical and applied problems of a combusion and an explosion. And on width of a working temperature interval, and on maximum speed of registered reactions in condensed environments the ETE method essentially surpasses (in temperatures - on thousands of degrees, in times - on the orders) all other kinetic techniques, in which the researched chemical conversion in a heterogeneous condensed mix is executed in space isothermic conditions.

The application of model samples, rolled - up from foils, permits to save a surface of reactant contact up to the moment of welding a more refractory component of a system. By using simple models the disolution constants in systems Ni-Al and Ti-Al were quantitatively calculate.

For systems with high exothermic reaction, but with low conductivity, the dilution method of a reacting mix by well conducting inert for registration of kinetic and macrokinetic parameters was used. The works with thermit systems, such as Ti-NiO, Ti-MoO3 and Ti-Fe2O3 were conducted.

Setup

The automated experimental setup for research of high-speed reactions by ElectroThermal Explosion method is created. The software for realization of experiment, analysis and data processing experimental ETE-thermograms is developed. The method is testing on powder samples (Ti + C, Ta + C, Ti + B, Ti + Ni, Ni + Al and etc.), and on model foil samples (Ni + Ti, Ti + Al, Ni + Al).

Application

The development of the combusion theory of such systems, as thermit - on the one hand and SHS objects (at first - system, capable to so-called gassless combusion) - with other hand, testifies that a main problem is absence of reliable data on macrokinetic (kinetic) of high-speed high-temperature reactions in these systems. In works of Merzhanov, Manelis, Zenin, Maltsev and their employees the valuable information on a mechanism and kinetic of high-speed high-temperature reactions was received from data on measurement of temperature fields and combusion speeds of condensed systems. However, for account of kinetic parameters by these methods are necessary a priori of the item of information on adequacy to real processes of mathematical models used by authors.

Such data, as a rule, are absent. ETE is today, as appear, unique experimental method, enabling without of the a priori assumptions of a mechanism of interaction with quantitative completeness to calculate the macrokinetic characteristics of processes in extremely wide interval of change of working parameters: temperatures (up to 4000 K) and conversion times (less than 1 ms).

The data, received the last 3-5 years with help ETE, were used for:

  • Construction of new models of gassless combusion;
  • Quantitative comparison of distinctions in reacting speeds in heterogeneous mixes: in static and in conditions of high-speed impact;
  • Substantation of a opportunity of gassless detonation.

The appropriate results were published in the authoritative international journals, reported on international conferences. It was marked, in particular, that using of high-temperature kinetic ETE-data expands an opportunity of the experts, studying of combustion and explosion in condensed environments, the same as in time use of kinetic shock pipes by an essential image has expanded an opportunity of study of a combusion mechanism of gases.