Studying the mechanism of electric explosion of metal conductors

Abstract

The article gives a description of the history of the development of research of electric explosion of metal conductors, the authors offer a modern view on the physics of the process of electric explosion. The result of such an explosion can be, in particular, the production of nanopowders, which today have found the widest application in industry, agriculture, medicine, and so on.

Full Text

1. Introduction An electric explosion of metal conductors is usually understood to mean the explosive destruction of a conductor with a powerful current impulse passing through it. When a metal conductor is rapidly heated to a temperature above the boiling point, a metal-liquid-vapor phase transition is observed, a dense metal plasma is formed and further formation of small particles, while the explosion products expand and cool. The products of the explosion flying away at high speed quickly cool down, a fine powder is formed. Having created suitable initial conditions for this experiment, particularly, nanopowders are possible to obtain. Today, nanopowders are widely used as raw materials for the production of ceramic, magnetic, and composite materials, as well as in the production of superconductors, solar cells, lubricant additives, and so on. The use of nanopowders in industry is also very extensive. These are diffusion welding technologies, the creation of protective and anti-friction coatings and the restoration of worn parts of mechanisms. Also, the intensity of the use of nanopowders in agriculture and the environmental protection industry increases annually in the extraction and processing of minerals, in water treatment, in cosmetology and medicine. This phenomenon is accompanied by current interruption and generation of high-voltage pulses. In addition, the formation of high power shock waves, the flow of chemical reactions and the formation of bright flashes of light is possible. Due to the fact that an electric explosion is realized under very different conditions (by energy level, by type of metal, by environment, by final result), the resulting effects are also very diverse. All this contributes to a detailed study of the present phenomenon - here, the study of thermophysical properties of metals at high temperatures. An electric explosion of high-temperature plasma can be used as a source in studies of controlled thermonuclear fusion [1, 2], in studies generation of powerful soft X-ray pulses as well as in works on the creation of light sources. In addition, the explosion of wires is used in breakers, fuses in various electrophysical installations. In connection with the above, more accurate knowledge of the mechanisms of the electrical explosion of metallic conductors is extremely important today. We want to consider the history of the development of this issue and formulate our thoughts on the mechanism of the explosion of conductors to better understand this process. 2. Background The first theoretical publications on the explosion of conductors date back to the second half of the 18th century. One of the founders of experiments was Michael Faraday in the middle of the 19th century. When a Leyden jar was discharged through a gold wire on the inner walls of the flask, he received a thin metal film. But by the middle of the 20th century the number of publications on the explosion of conductors exceeded 800. It becomes obvious that the electrical explosion of conductors belongs to a poorly studied area of the interaction of metals with electric and magnetic fields. For example, the electrical conductivity of metals has been well studied only in the condensed state and in the ideal state plasma at a temperature of the order of 104 K. And such states as the vicinity of the critical point are still the subject of research. In connection with the foregoing, the study of the mechanism for the realization of an electric explosion of metallic conductors seems to us extremely important. Nanopowders can be obtained by electrical explosion of a conductor by passing through it a powerful current pulse with a duration of about 1 microsecond and a density from 104 to 106 A/mm2. Such impulse heating of the metal can be carried out by discharging a charged capacitor through a thin wire. A wire with a diameter of 0.1 to 1.0 mm is used for this purpose. An electric explosion is accompanied by the generation of shock waves and creates the possibility of rapid heating of metals at a rate of more than 108 ÷ 1010 K/sec to high temperatures