| Electrical explosion a new method applied to preparation of nanoparticles for much good superiority of high energy efficiency, adjustable process parameters, and high purity products of preparation and so on. Usually the materials select wires as electrical explosion material such as Cu, Ni, and Mo. While some materials are difficult to be made into wire, the powders as electrical explosion material also have a special advantage, not only could be applied to electrical explosion spraying but also electrical explosion materials synthesis. This article made an application of natural graphite powder as electrical explosion material, which has some innovative and practical industrial applications value.A device for preparation of carbon nanoparticles by powder electrical explosion was designed, which based on the existing research results of our laboratory researchers. The device mainly consists of constraints explosive equipment, powder feeding, high voltage charging circuit, and powder collecting equipment. The graphite powder delivered quantitatively into the upload feed rod by powder feeding equipment.The electric telescopic pole drives upload feed rod movement, and then the upload feed rod formed a constrained tube with the constraint sleeve, which had a closed structure with closed at one end and opened at another end. When the graphite powder in upload feed rod moved to a suitable location away from the high voltage electrode, gas discharge occurred between the electrodes and powder, at the same time the large pulse current imported into powder, and then the graphite powder occurred electrical explosion within in constraint tube. With this device combined natural graphite powder as raw material for electrical explosion tests, under different initial voltage with certain constraint tube cross-section, and different constraint tube cross-section with certain initial voltage. Analysis on morphological changes of the products of preparation by TEM, and Raman characterization analysis under different initial voltage with certain constraint tube cross-section.The products of preparation exist in the form of particles, when the constraint tube cross-sectional diameter of 4, 5, and 6mm with under initial voltage 8kv. There exist polyhedral particles except for spherical particles in the products of preparation in smaller cross section constraint tube. The polyhedral particles decreased with the increased constraint tube cross-section. The products of preparation contained particles and sheets morphology, when the constraint tube cross-sectional diameter of 4mm with under initial voltage 8, 9, 10 and 11 kv. The particles decreased and sheets increased with the increased voltage. Graphite powder within in constrained tube occurredelectrical explosion and liquid phase and vapor components coexist simultaneously in the explosion instant products due to electrical explosion non-equilibrium processes.When the explosive products ejected from constraint tube liquid phase components that exist in the explosion instant products, which coagulated to form spherical particles and vapor phase sublimated to polyhedral particles, while the shock wave generated with explosion instant stripped graphite as several layers. The particles decreased and sheet increased in the products of preparation due to the vapor proportion is greater than the liquid in the explosion instant products when energy density deposited on the powder increased with the increased initial voltage. Analysis on carbon nanoparticles,while the constraint tube cross-sectional diameter of 4mm with under different initial voltage by Raman spectroscopy. The results show that graphite occurred nano after electrical explosion and the particles are nano graphite particles, sheets are graphene in the products of preparation. The products of preparation existed large amounts of sheets especially under 11 kv. Raman spectroscopy analysis and calculate intensity ratio of IG’ / IG, that could be confirmed the sheets are four layers of graphene. |
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