US3436465A - Methods and arrangements for melting material which melts only with difficulty - Google Patents

Methods and arrangements for melting material which melts only with difficulty Download PDF

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Publication number
US3436465A
US3436465A US508271A US3436465DA US3436465A US 3436465 A US3436465 A US 3436465A US 508271 A US508271 A US 508271A US 3436465D A US3436465D A US 3436465DA US 3436465 A US3436465 A US 3436465A
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United States
Prior art keywords
sheath
melting
discharge
gas discharge
materials
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Expired - Lifetime
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US508271A
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English (en)
Inventor
Jacob Willem De Ruiter
Anton Willemstein
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Philips North America LLC
US Philips Corp
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US Philips Corp
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    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
    • H05H1/00—Generating plasma; Handling plasma
    • H05H1/24—Generating plasma
    • H05H1/26—Plasma torches
    • H05H1/30—Plasma torches using applied electromagnetic fields, e.g. high frequency or microwave energy
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J6/00—Heat treatments such as Calcining; Fusing ; Pyrolysis
    • B01J6/005—Fusing
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/16—Remelting metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
    • C22B9/00—General processes of refining or remelting of metals; Apparatus for electroslag or arc remelting of metals
    • C22B9/16—Remelting metals
    • C22B9/22—Remelting metals with heating by wave energy or particle radiation
    • C22B9/226—Remelting metals with heating by wave energy or particle radiation by electric discharge, e.g. plasma
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B11/00—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method
    • C30B11/04—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method adding crystallising materials or reactants forming it in situ to the melt
    • C30B11/08—Single-crystal growth by normal freezing or freezing under temperature gradient, e.g. Bridgman-Stockbarger method adding crystallising materials or reactants forming it in situ to the melt every component of the crystal composition being added during the crystallisation
    • C30B11/10—Solid or liquid components, e.g. Verneuil method
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D11/00—Arrangement of elements for electric heating in or on furnaces
    • F27D11/06—Induction heating, i.e. in which the material being heated, or its container or elements embodied therein, form the secondary of a transformer
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B11/00—Heating by combined application of processes covered by two or more of groups H05B3/00 - H05B7/00
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • Metal powder in compressed and sintered form is used as a fusing electrode of an electric arc discharge, but the pulverulent starting substance is likewise supplied to the discharge are in pulverulent state, in which event it falls down through the flame.
  • the melted material is collected on the lower side in a cooled crucible.
  • the latter method has the advantage that it is not necessary to start first with the manufacture of compressed and sintered electrodes. It may also be used for non-metallic materials.
  • the temperatures in'the discharge are different from place to place and decrease especially from the centre towards the outer side so that only part of the discharge volume has the correct temperature at which material particles of a given size melt. Furthermore, it is very time-consuming to pulverize material to particles of substantially equal size.
  • the invention has for its object to avoid this disadvan tage and relates to a method and an arrangement for melting pulverulent material which melts only with difiiculty by means of an electricgas discharge inside a sheath of high melting-point material, for example, of quartz glass, the gas discharge being operative in the induction field of a high-frequency coil which surrounds the sheath and is connected to a high-frequency generator.
  • the pulverulent material is fed to the working space while the sheath is rotating, as a result of which the powder spreads along the circumference of the sheath and constitutes a wall layer and said layer is heated on the inner side to the melting temperature of the material by the heat developed in the gas discharge.
  • the method in accordance with the invention may be used for melting pulverulent material and conducting away the melted material.
  • the rotatable sheath is arranged vertically and provided with a transverse wall having a small aperture and constituting the lowermost boundary of the gas discharge volume.
  • the pulverulent material supplied is collected immediately above this transverse wall.
  • a continuous sup ply of powder may take place on the upper side of the working space so that the melted material flows away con tinuously through the aperture in the transverse wall.
  • the diameter of the aperture in the transverse wall is dependent upon the material to be melted, in which case surface stress, specific weight and similar material properties must be taken into account.
  • provi sion is made in the transverse wall at the Centre of the aperture of a mandril of refractory material which is connected at a plurality of points by narrow radial strips with the transverse wall.
  • the mandril preferably consists of a material of satisfactory thermal conductivity and having a high melting point, so that the temperature is substantially the same at all places as a result of a satisfactory heat distribution.
  • the radial strips must have a sutficient strength to resist the pressure of materials having a comparatively low flow capacity.
  • This pressure may be considerable if the flow of the material must be forced and a high pressure of, for example, a few atmospheres, is maintained in the discharge space. It is also possible to exhaust the space beneath the transverse wall to a low pressure. Since the liquid mass of material fills the aperture, a pressure difference may be maintained without a substantial loss of material being involved.
  • the gas in the discharge space has a low pressure.
  • the material to be melted may be degased simultaneously, as a result of Which the formation of gas bubbles in the melted material is counteracted.
  • the high-frequency gas discharge satisfactory results can be obtained in the pressure range of 1-1O torr, although the flows of whirling gas which are associated with the rotation of the sheath and which maintain the stabilization of the discharge have become less important due to the low pressure.
  • the lengths of the free paths of the electrically charged gas particles are sufficient for the use of magnetic stabilization with the aid of a comparatively low magnetic field of constant strength the lines of force of which are parallel to the axis of the sheath. Under the influence of this field, the charged particles may cover circular paths and particles having outwardly directed speeds are conducted back into the discharge volume.
  • the method in accordance with the invention is of particular importance for the manufacture of granular material.
  • the sheath rotates at a sufficient speed, the coherence of the material flowing out of the aperture in the transverse wall is broken up, as a result of which the material spreads from the aperture in separate drops the size of which is dependent upon the flow capacity and the surface stress of the material and upon the speed of rotation of the sheath.
  • grains of material of equal size will be obtained which have a substantially spherical shape.
  • the method in accordance with the invention may be used for manufacturing high melting-point alloys.
  • the starting substances required for an alloy are supplied separately in pulverulent state to the space situated inside the sheath and above the working space, these substances are mixed as a result of the whirling caused by the rotation.
  • the powder particles of the more readily meltable starting substance will melt more rapidly and wet the grains melting only with ditliculty, whereupon the melting of these grains is continued and the melted alloy is formed.
  • High melting-point materials for the manufacture of fuel elements of reactors may be manufactured in the same manner. It is known to use uranium carbide or plutonium carbide as mixed carbides by adding other carbides such as zirconium carbide, niobium carbide, tantalum carbide and thorium carbide, in which event the desired composition can be obtained by melting in the high-frequency gas discharge instead of carrying out the time-consuming sintering process at high temperature.
  • the materials obtained in successive melting phases have a high density while the starting materials are distributed over the composed matrix in a uniform manner.
  • Such an arrangement consists of a rotating gas discharge burner comprising the tubular sheath 1 which is made of high-melting point material, for example, of quartz glass.
  • the sheath 1 is provided at both ends with ball-bearings 2 and 3 which are arranged in flat plates 4 and 5. These plates are connected to each other by rods 6 and 7.
  • the sheath is vertically arranged and covered on the upper side with a hood 8 secured to the fiat plate 4.
  • Two tubes 9 and 10 for supplying one or more gases suitable for producing an electric discharge are provided in the hood.
  • an electrically insulatecl through-connection 11 consisting, for example, of a vitreous enamel
  • two current conductors 12 and 13 are passed through the hood 8 into the sheath, the ends of these conductors located inside the sheath being spaced apart by a short distance and constituting electrodes 14 and 15 between which an arc discharge can be produced by the application of an electric voltage thereto.
  • the gas discharge inside the sheath 1 can be ignited.
  • the high-frequency coil 16 which surrounds the sheath 1 and which is disposed in the current circuit of a high-frequency generator, for example, a magnetron oscillator, produces a magnetic induction field in the proximity of the auxiliary discharge.
  • the position of the high-frequency coil 16 in which the gas discharge is ignited is indicated with dotted lines. It is therefore rendered possible to relatively displace the coil and the sheath, in the embodiment the sheath 1 being displaceable along the supports 17 and 18.
  • a transverse wall 19 comprising an aperture 20.
  • a crucible 21 is mounted below this transverse wall and has a rod-shaped support 22 by which the crucible 21 bears on a transverse plate 23.
  • This plate is secured by means of a ring 24 to the lower flat plate 5.
  • the ring is provided with an aperture 25 which serves for drawing ofi gas and which may communicate with a vacuum pump for reducing the pressure in the lower portion of the sheath 1.
  • the ball-bearings 2 and 3 are closed by means of locking rings 26 and 27 of a resilient material.
  • the crucible 21 may be artificially cooled by a cooling 4 liquid for which an inlet and an outlet 28 and 29 are indicated on the lower side of the transverse plate 23.
  • the inner ring of the lower ball-bearing 3- has secured to it a rotary disc 30 which is provided with a groove for a rope establishing the transmission required for the rotation of the sheath 1 with a driving gear.
  • the discharge is limited by the adjustment of the speed of rotation of the sheath and of the intensity of the gas supply to a volume inside the sheath 1 of a cross-section such that the wall of the sheath is not damaged by the developed heat.
  • the sheath 1 is displaced upwards along the supports 17 and 18, the transverse wall 19 approaches the gas discharge.
  • the starting substance to be melted is introduced into the working space through a tube 32 which projects outwards through the hood 8 and which is provided with a filling funnel 33. Under the influence of the rotation, the powder is scattered along the wall of the sheath 1 and is at the same time moved downwards so that an accumulation 34 is formed in the proximity of the transverse wall 19.
  • the gas discharge volume may be adjusted by the control of the speed of rotation of the sheath so that the powder particles constituting the inner surface of the collected pulverulent mass melt.
  • a kind of crucible is then formed in the sheath which protects the sheath from excessive heating.
  • the heat penetrating into the powder brings about si-ntering of the powder under the melting layer and consequently constitutes a sufiicient thermal resistance.
  • the sheath may be cooled on the outer side. No difiiculties are involved in adjusting the supply of the pulverulent starting substance so that an equal quantity of material is conducted away by melting, which material is collected in the crucible 21.
  • a method of melting materials which melt only at relatively high temperatures comprising supplying gases suitable for producing an electric discharge in a working space surrounded by a sheath of high melting point material, maintaining said gas discharge in said sheath by the induction field of a high frequency coil, rotating said sheath while said melting materials are supplied to said working space in a pulverulent state, the speed or rotation being such that the material powder spreads along the inner side of said sheath to form a wall layer, and heating said wall layer to its melting temperature by the heat developed by said gas discharge.
  • a method of melting materials which melt only at relatively high temperatures as claimed in claim 1 further conducting away the melted material through an aperture in a transverse wall provided in said sheath.
  • An apparatus for melting materials which melt only at relatively high temperatures comprising an electric gas discharge burner which is provided with a sheath of high melting point material, means for rotating said sheath about its axis, a high frequency coil surrounding said sheath, and second means for displacing said sheath along 5 the longitudinal axis thereof relative to said high frequency coil.
  • An apparatus for melting materials which melt only at relatively high temperatures as claimed in claim 8 wherein said thickened parts are hollow tubes of high melting point, non-conducting material, said tubes being cooled by a coolant conducted through said tubes.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Physics & Mathematics (AREA)
  • Organic Chemistry (AREA)
  • Metallurgy (AREA)
  • Plasma & Fusion (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Electromagnetism (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Power Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Thermal Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Furnace Details (AREA)
  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
  • Manufacture And Refinement Of Metals (AREA)
US508271A 1964-12-23 1965-11-17 Methods and arrangements for melting material which melts only with difficulty Expired - Lifetime US3436465A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
NL6414964A NL6414964A (fr) 1964-12-23 1964-12-23

Publications (1)

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US3436465A true US3436465A (en) 1969-04-01

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US508271A Expired - Lifetime US3436465A (en) 1964-12-23 1965-11-17 Methods and arrangements for melting material which melts only with difficulty

Country Status (9)

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US (1) US3436465A (fr)
AT (1) AT272681B (fr)
BE (1) BE674143A (fr)
CH (1) CH444988A (fr)
DE (1) DE1540994A1 (fr)
FR (1) FR1461851A (fr)
GB (1) GB1126037A (fr)
NL (1) NL6414964A (fr)
SE (1) SE313883B (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3783167A (en) * 1971-02-16 1974-01-01 Tetronics Res Dev Co Ltd High temperature treatment of materials
USRE28570E (en) * 1971-02-16 1975-10-14 High temperature treatment of materials
US3932171A (en) * 1972-09-24 1976-01-13 Tetronics Research And Development Company Process for high temperature treatment of materials

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3124633A (en) * 1960-09-15 1964-03-10 Certificate of correction
US3250842A (en) * 1963-01-15 1966-05-10 Atomic Energy Commission Electron beam zone refining

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3124633A (en) * 1960-09-15 1964-03-10 Certificate of correction
US3250842A (en) * 1963-01-15 1966-05-10 Atomic Energy Commission Electron beam zone refining

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3783167A (en) * 1971-02-16 1974-01-01 Tetronics Res Dev Co Ltd High temperature treatment of materials
USRE28570E (en) * 1971-02-16 1975-10-14 High temperature treatment of materials
US3932171A (en) * 1972-09-24 1976-01-13 Tetronics Research And Development Company Process for high temperature treatment of materials

Also Published As

Publication number Publication date
FR1461851A (fr) 1966-12-09
CH444988A (de) 1967-10-15
AT272681B (de) 1969-07-10
NL6414964A (fr) 1966-06-24
DE1540994A1 (de) 1970-01-15
SE313883B (fr) 1969-08-25
BE674143A (fr) 1966-06-21
GB1126037A (en) 1968-09-05

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