electic explosion (rus. электровзрыв) — a method to generate fine-grained metal, oxide, nitride and carbide powders by means of electric explosion of an electrical conductor (metal wire 0.1–1.0 mm in diameter) while a high pulse current passes through it, 10–5–10–7 seconds long and with 104–106 А·mm–2 density.

Description

Wire electrical explosion is an abrupt change in the physical state of a metal as a result of intensive release of energy by passing a pulsed current of high density with shock waves, which heats the metal rapidly to temperatures above 104 K.

At the initial phase of the electrical explosion, Joule heating of the wire leads to its linear expansion at quite a low rate of 1-3 m·s-1. At the stage of the explosion, when the pulsed current goes through, the metal gets overheated to temperatures above the melting point, the expansion of the wire occurs at a rate of up to 5·103 m·s-1, and the overheated metal disintegrates in an explosion-like manner. Pressure and temperature at the front of the shock waves reach several hundred MPa and ~104 K, respectively. Very small particles generate due to condensation in a rapidly expanding vapour flow. By adjusting the conditions of the explosion, powders can be produced with a particle size between 50 nm and more. The average particle size steadily decreases as the current density goes up and the pulse becomes shorter.

Electrical explosion in inert atmosphere is the technique that enables the production of metal and alloy powders. When additional reagents are injected into the reactor (air, a mixture of oxygen and inert gas, nitrogen, distilled water, decane C10H22, paraffin, industrial oil), ultradisperse powders of oxides, nitrides, carbides, or mixtures thereof can be produced.

The particle size distribution is log-normal with a maximum of 10-500 nm for fine powders, produced by the electrical explosion. Such particles of metals and alloys are spherical, while nitride and carbide powder particles are faceted.

Author

  • Gusev Alexander I.

Sources

  1. Gusev A. I. Nanomaterials, Nanostructures, and Nanotechnologies (in Russian) // Fizmatlit, Moscow (2007) - 416 pp.
  2. Gusev A. I., Rempel A. A. Nanocrystalline Materials. — Cambridge: Cambridge International Science Publishing, 2004. — 351 p.

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