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The Technology of the Nanopowder Preparation by the Method of the Wire Electrical Explosion and the Structural Optimization of Electrical Explosion Device

Author: ZhouLiang
Tutor: HanZuo；Дамошенко В.Г.
School: Jilin University
Course: Condensed Matter Physics
Keywords: electrical explosion technique electrical explosion device structure design nanopowder particle distribution
CLC: TB383.1
Type: Master's thesis
Year: 2009
Downloads: 65
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Abstract

Because the nanomaterial has the particular property that regular coarse crystal doesn’t have, it is paid quite a lot of attention. The investigation of the method of nanopowder preparation is significant. Through the compare to the regular preparation method, a series of advantages of wire electrical explosion method are proposed: the efficiency of energy transfer is high; according to the property of nonapowder that will be prepared the experimental parameter could be adjust handily; the distribution of the particulate size of nanopowder is uniform; the generalization of the method is better; the cost of the device is low; the structure is simple; the total weight and the volume is small etc. So it is significant to investigate nanopowder preparation by the method of wire electrical explosion.The phenomenon and process of wire electrical explosion that is operated by high-power impulse is introduced. According to the different amount of the input energy the electrical explosion is separated three types and they are slow explosion, fast explosion and over fast explosion. It is demonstrated that the oscillating LC circuit is the most convenient and quick circuit that can complete the electrical explosion. The magnet fluid dynamic theoretical model of electrical explosion and the process of electrical explosion technology are accounted. The primary production of the comminuted metal wire is in gas phase (30% ion, 30% atom, molecule, shiver) and in over heated liquid phase (40%). And then the nanopowder is emerged.In this paper it is pointed out that the structure of electrical explosion device is inappropriate. When the flow mixed the explosion production is operating between the explosion cavity and dynamical filter, it would be extruded, and the possibility of sintered powder increased, and these are the main disadvantage of electrical explosion device that has applied. Otherwise the structure of powder collector which is inappropriate is also a disadvantage. There are always some“deadlocks”, when shock wave that wire electrical explosion generated move in it, and the powder suffered impulsion charge and extrusion several times. In this instance the nanopowder is agglomerated partly. So the electrical explosion device that has applied can not obtain the expected result to control the distribution of powder completely. In order to get over the shortage of structure, the whole structure of the electrical explosion device is improved based on the experimental investigation, theoretical estimate and particle distribution dynamics. The voltage input parts, discharge chamber, explosion cavity, wire delivering device, powder collector and the structure of gas separation component, electricity distribution device are designed, and the experimental data collection system and measurement system are established. The basic technical capability, structural characteristics, the formation procedure of task period and safety operation regulations are presented, and the problems about production of the device are discussed.The characteristic parameter of electrical explosion device is confirmed by the short circuit experiment: loop inductance, wave impedance, and effective resistance. The explosion experiment that used aluminium wire, iron wire, aluminium-iron wire is achieved. Depended on the device the nanopowder is produced, and it is discovered that the dimension of the agglomeration of nanopowder could reduce above one order of magnitude.In addition the electrical explosion parameters that influence the distribution of powder such as the energy of imported wire, the diameter of explosion wire and gas pressure are investigated. As a result the distribution of the final production of electrical explosion increased, when the input energy increased; the average particle size of nanopowder increased when the diameter of explosion wire increased under the condition of identical input energy. In general, the particle size of powder increased along with the rise of gas pressure in the explosion cavity. So the distribution of powder could be controlled by adjusting the parameter.

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