Electromagnetic Levitation for Containerless Processing and Refining of Metals
In response to the growing need to handle high temperature reactive metals and alloys in today�s manufacturing industry, Rice has developed an advanced method for refining pure or precious metals and alloys by a new, more powerful electromagnetic levitation technique. This containerless method for processing allows high-purity metals and alloys to be zone-refined free from the presence of contaminants from crucibles. This novel technology is comprised of a horizontal levitator capable of suspending sizable specimens and operating in either continuous or batch mode. The levitator has a generally cylindrical levitation zone formed by positioning a plurality of conductors longitudinally about an axis and passing alternating current in opposite directions through adjacent pairs of conductors. In this configuration, when current is passed through the conductor, a tunnel-shaped levitation zone with openings at each end is formed. Metal specimens can be placed individually or fed into the levitation zone through one end and removed from the opposite end. It is also possible to access the levitation zone through the levitator�s side. Rice�s levitation technology provides a strong levitation force with minimal heating. The electromagnetic levitator suspends metal horizontally in either solid or liquid form and keeps it from touching elements of a heating medium, such as the crucible, that may be partially melted at the very high temperatures required to melt the metal. If the extremely hot metal were to physically contact a partially melted crucible, it would mix with and thereby be contaminated with some of the crucible material. Current practice includes coating the crucible with a layer, or "skull," of the metal to prevent contamination. Rice researchers have developed this electromagnetic levitation technology to be used in handling very high-temperature metals in a controlled manner. The technology comprises a horizontal levitator capable of suspending sizable specimens and operating in either continuous or batch mode. The levitator also comprises a generally cylindrical levitation zone formed by positioning a plurality of conductors longitudinally about an axis and passing alternating current in opposite directions through adjacent pairs of conductors. In this configuration, when current is passed through the conductor, a tunnel-shaped levitation zone having an opening at each end is formed. Metal specimens can be placed in the levitation zone individually or fed into the levitation zone through one end and removed therefrom through the opposite end. It is also possible to access the levitation zone through the side of the levitator. Rice�s levitation technology provides a strong levitation force with minimal heating in the specimen. The present levitator can levitate even large specimens indefinitely without causing melting and/or boiling of the specimen. The electromagnetic levitator suspends the metal horizontally in either solid or liquid form and keeps it from touching elements of the heating medium, such as the crucible, that itself may be partially melted at the very high temperatures required to melt the metal. If the very-high temperature metal were to physically contact a partially melted crucible, it would mix with and thereby be contaminated with some of the material comprising the crucible. Current practice includes coating the crucible with a layer, or "skull," of the metal to prevent contamination. Benefits of the Technology . Metals with very high melting points can be melted and cast without being contaminated by furnace elements and without the use of a "skull." . Bars of metal alloy can be zone-refined by melting a slice, or zone, of the bar and moving the melted zone along the length of the bar. Impurities are trapped and collected in the melted zone and herded to the end of the bar which can be severed and discarded. How the Technology Works The levitator consists of a single conductor tube bent to form several horizontal straight sections. Water is used as a coolant for the levitator and passed throughout the tubing to prevent the conductor from melting. The conductor tube is then connected to an alternating current source which provides the magnetic force needed. Improvements Over Previous Levitators The idea of levitating metals is not new, but previous technologies developed to achieve that purpose have a number of shortcomings that Rice's new technology overcomes. The electromagnetic levitator developed at Rice levitates objects horizontally, as opposed to vertically in previous levitators. Rice's levitator can also handle larger objects and allows for easier inspection and manipulation of levitated objects. Another improvement is a stable levitation zone that will not lose portions of melted specimens; and specimens can be fed into the levitator individually in one end and removed from the other end, or they can be inserted through the side of the device. A strong levitation force can support large specimens indefinitely. Also, the levitation device is separate from the heating device, allowing for levitation without significant heating of the specimen.Patents:
US 5,887,018
Inventor(s): Prof. Yildiz Bayazitoglu
Type of Offer: Licensing
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