Induced capillary breakdown of solid and hollow jets of molten metals, alloys, and salts with a melting temperature up to 1600°C is studied by experiment. Granulation technology is developed and specimens of solid and hollow monodispersed granules are obtained. Granules of lead and rare-earth metals have found application in cryogenic technology. Other areas for the use of monodispersed granules are considered. Substances that are in a granular, finely-dispersed condition, are used in various areas of science and technology. They may be granules of metals, alloys, or different chemical compounds. The efficiency of production processes using these materials depends markedly on granule parameters. Therefore an important task is preparation of monodispersed granules with identical and production properties. Use of these granules makes it possible to calculate quite precisely the characteris- tics of processes and to optimize them. Technology has been developed at the Center of High Technologies of the Moscow Power Engineering Institute (TsVT MEI) for preparing monodispersed granules, based on the physical effect of induced capillary jet breakdown (ICJB) (1). This effect arises with creation at the surface of a laminar jet of regular resonant perturbations for a given jet frequency (Fig. 1). The amplitude of these perturbations increases over the length of a jet as a result of which there is creation of a jet of monodispersed droplets ordered within space. During cooling of droplets in the time of descent in a heat exchange cham- ber conditions are created for their crystallization in the form of monodispersed spherical granules. The parameters (size, shape, structure, etc.) of these granules have a high level of uniformity. It is impossible to obtain this quality of granules using traditional granulation technology, even after sorting them with respect to shape and size. It should be noted that in prepar- ing monodispersed granules by ICJB the energy expended is less than in the case of the extensively used polydispersed break- down of a jet during granulation. This is connected with the fact that during ICJB a jet is an amplifier of harmonic perturba- tions created in its initial section. Forces of surface tension lead to an increase in the amplitude of these perturbations and breakdown of a jet into monodispersed droplets. In order to perturb a jet, it is sufficient to use a piezoelement with electric power supplied to it not exceeding 1 W. The reverse picture is observed during granulation by means of jet atomization. In this case surface tension forces plays a stabilizing role, and therefore in order to provide melt atomization it is necessary to affect it by a high-velocity stream of gas or liquid. The technology developed is ecologically clean and waste-free. The granulators created make it possible to prepare monodispersed granules from an extensive series of materials, including various metals and their alloys with a melting temperature up to 1600°C. A granulator (Fig. 2) is a closed circulation circuit, filled with helium and consisting of the following main components: droplet generator with a perturbation system and crucible, a heat exchange chamber with a granule collector, and a system for cleaning oxygen from helium. Emergence of the jet occurs under the action of excess gas pressure above the melt in a crucible. The magnitude of this pressure is controlled and
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