Electron-Beam Furnace

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Electron-Beam Furnace

 

an electric furnace in which electric energy is transformed into heat directly in a metal being remelted as a result of bombardment with electrons emitted from an electron gun. The electrons are accelerated by a high-voltage electric field (10–35 kilovolts) under low-pressure conditions (less than 10 millinewtons per m2).

Electron-beam furnaces used in the metallurgy of pure metals and alloys consist of the following units and systems (Figure 1): an electron emitter (electron gun) with a cathode, accelerating anode, and magnetic focusing system; a melting chamber with gating devices and a crystallizer (a mold or crucible) for the metal; a vacuum system; mechanisms for transporting the metal to be remelted; and a power supply with an automatic control system. The metal to be remelted is introduced into an electron-beam furnace through a vacuum seal in the form of a consumable electrode, ingot, single crystal, or powder. The molten metal runs off in drops either into a water-cooled crystallizer—a mold (in ingot melting) or crucible (in melting in crucibles with a skull, for the production of shaped castings, and in the growing of single crystals)—or into cold, water-cooled hearth reservoirs (in refining molten metal).

In industry, electron-beam furnaces with capacities in excess of 1 megawatt are used for remelting steel ingots with diameters up to 1,000 mm, heat-resistant alloy ingots with diameters up to 500 mm, and refractory metal ingots with diameters up to 280 mm. The electrical efficiency of electron-beam furnaces ranges from 0.6 to 0.8. The specific power consumption is 1–2 kilowatt-hours per kg (kW-hr/kg) for steel, 10–15 kW-hr/kg for niobium, tantalum, and molybdenum, and 20–40 kW-hr/kg for tungsten. As of

Figure 1. Designs of electron-beam furnaces: (a-e) and (g) with electrostatic electron guns, (f) with magnetron electron gun; (EG) electron gun, (AC) annular cathode, (LC) linear cathode, (SC) spiral cathode, (DC) disk cathode, (AA) accelerating anode, (MFS) magnetic focusing system, (MDS) magnetic deflection system, (CE) consumable electrode, (Ch) free-flowing charge, (C) single crystal, (I) ingot, (Cry) crystallizer, (CWS) crucible with skull, (Cru) crucible, (CM) casting mold, (CH) cold hearth, (VS) vacuum system

1978, a 7.2-megawatt electron-beam furnace was in the planning stage, designed to remelt steel ingots with diameters up to 2,000 mm (with a cold hearth).

REFERENCES

Elektronnye plavil’nye pechi. Moscow, 1971.
Egorov, A. V., and A. F. Morzhin. Elektricheskie pechi. Moscow, 1975.

A. V. EGOROV and A. F. MORZHIN

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
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PHOTO : electron-beam furnace at the Axel Johnson Metals plant in Morgantown, PA.