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Title: An analysis of the break-up of liquid metals by a twin-roller process
Author: Day, L.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1978
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The development of a novel process for the atomization of metals is presently being carried out at the Department of Metallurgy and Materials Technology, University College of Swansea. The process consists of directing a stream of molten metal into a small gap between a pair of counter rotating rollers. The present study is concerned with the construction of a mathematical model of the observed disintegration of the liquid metal sheet produced below the rollers. The model developed is based upon a mechanism featuring perforations occurring in the sheet, a mechanism suggested by the study of available photographic work. These perforations propagate rapidly in the sheet and drops are produced by the break-up of the extending liquid threads formed between them. The subsequent cooling of these drops in the air results in the production of metal powder. The analysis presented provides a good order of magnitude agreement with the available experimental results. The origin of the perforations is also discussed and cavitation, fsimilar to that occurring in lubricated bearings, is proposed to be the cause. Through cavitation the model can easily be adapted to predict all the observed experimental trends. Some further characteristics of the liquid metal sheet, such as the contraction of the sheet edge, are also considered, and experimental support is given for the predicted results. Further work should provide a more rigorous test of the model and also should determine the extent to which the model can be applied to high rotational speeds of the rollers. Specific references to the published work of other authors are made in the text of the thesis and are listed at the end of the individual chapters.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available