EP0121683B1 - Giessen in exothermer reduzierender Atmosphäre - Google Patents

Giessen in exothermer reduzierender Atmosphäre Download PDF

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Publication number
EP0121683B1
EP0121683B1 EP19840101458 EP84101458A EP0121683B1 EP 0121683 B1 EP0121683 B1 EP 0121683B1 EP 19840101458 EP19840101458 EP 19840101458 EP 84101458 A EP84101458 A EP 84101458A EP 0121683 B1 EP0121683 B1 EP 0121683B1
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Prior art keywords
strip
gas
reducing
casting
atmosphere
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Expired
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EP19840101458
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English (en)
French (fr)
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EP0121683A1 (de
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Howard Horst Liebermann
John Adam Wellslager
Lance Davis
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Allied Corp
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Allied Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B22D11/0611—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars formed by a single casting wheel, e.g. for casting amorphous metal strips or wires
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/06—Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B22D11/0637—Accessories therefor
    • B22D11/0697—Accessories therefor for casting in a protected atmosphere

Definitions

  • the invention relates to the casting of metal strip directly from a melt, and more particularly to the rapid solidification of metal directly from a melt to form substantially continuous metal strip.
  • the metal can be cast in an inert atmosphere or a partial vacuum.
  • US ⁇ A ⁇ 3 862 658 and US-A-4 202 404 disclose flexible belts employed to prolong contact of cast metal filament with a quench surface.
  • US-A-4,154,283 discloses that vacuum casting of metal strip reduces the formation of gas pocket defects.
  • the vacuum casting system taught by Ray et al. requires specialized chambers and pumps to produce a low pressure casting atmosphere.
  • auxiliary means are required to continuously transport the cast strip out of the vacuum chamber.
  • the strip tends to weld excessively to the quench surface instead of breaking away as typically happens when casting in an ambient atmosphere.
  • US ⁇ A ⁇ 4,301,855 discloses an apparatus for casting metal ribbon wherein the molten metal is poured from a heated nozzle onto the outer peripheral surface of a rotary roll.
  • a cover encloses the roll surface upstream of the nozzle to provide a chamber, the atmosphere of which is evacuated by a vacuum pump.
  • a heater in the cover heats the roll surface upstream from the nozzle to remove dew droplets and gases from the roll surface.
  • the vacuum chamber lowers the density of the moving gas layer next to the casting roll surface, thereby decreasing formation of air pocket depressions in the cast ribbon. The heater helps drive off moisture and adhered gases from the roll surface to further decrease formation of air pocket depressions.
  • US-A-3,861,450 discloses a method and apparatus for making metal filament.
  • a disk-like, heat-extracting member rotates to dip an edge surface thereof into a molten pool, and a non-oxidizing gas is introduced at a critical process region where the moving surface enters the melt.
  • This non-oxidizing gas can be a reducing gas, the combustion of which in the atmosphere yields reducing or non-oxidizing combustion products at the critical process region.
  • a cover composed of carbon or graphite encloses a portion of the disk and reacts with the oxygen adjacent the cover to produce non-oxidizing carbon monoxide and carbon dioxide gases which can then surround the disk portion and the entry region of the melt.
  • non-oxidizing gas disrupts and replaces an adherent layer of oxidizing gas with the non-oxidizing gas.
  • the controlled introduction of non-oxidizing gas also provides a barrier to prevent particulate solid materials on the melt surface from collecting at the critical process region where the rotating disk would drag the impurities into the melt to the point of initial filament solidification.
  • the exclusion of oxidizing gas and floating contaminants from the critical region increases the stability of the filament release point from the rotating disk by decreasing the adhesion therebetween and promoting spontaneous release.
  • US ⁇ A ⁇ 3,861,450 addresses only the problem of oxidation at the disk surface and in the melt.
  • the flowing stream of non-oxidizing gas taught by Mobley, et al. is still drawn into the molten pool by the viscous drag of the rotating wheel and can separate the melt from the disk edge to momentarily disturb filament formation.
  • the particular advantage provided by Mobley, et al. is that the non-oxidizing gas decreases the oxidation at the actual point of filament formation within the melt pool.
  • US-A-3,861,450 fails to minimize the entrainment of gas that could separate and insulate the disk surface from the melt.
  • US-A-4,282,921 and US-A-4,262,734 disclose an apparatus and method in which coaxial gas jets are employed to reduce edge defects in rapidly quenched amorphous strips.
  • US ⁇ A ⁇ 4,177,856 and US-A-4,144,926 disclose a method and apparatus in which a Reynolds number parameter is controlled to reduce edge defects in rapidly quenched amorphous strip. Gas densities and thus Reynolds numbers, are regulated by the use of vacuum and by employing lower molecular weight gases.
  • the invention provides an apparatus and method for efficiently casting smooth metal strip and substantially preventing the formation of gas pocket defects therein.
  • the apparatus of the invention for casting metal strip comprising a moving chill body having a quench surface, nozzle means for depositing a stream of molten metal on a quenching region of said surface to form said strip, and gas supply means is characterized in that the gas supply means acting as a source of carbon monoxide forms part of depletion means which also include a delivery means located adjacent to and upstream from said nozzle means for supplying carbon monoxide to a depletion region adjacent to and upstream from said quenching region to create a low density reducing atmosphere with said depletion region by exothermic reaction of said carbon monoxide.
  • the method of the invention for casting metal strip comprising the steps of moving a chill body having a quench surface at a selected speed depositing a stream of molten metal on a quenching region of said quench surface to form said strip and supplying a gas to the chill body, is characterized in that a reducing gas is supplied to a depletion region located adjacent to and upstream from said quenching region and is reacted exothermically to lower the density thereof and provide a low density reducing atmosphere within said depletion region.
  • the method and apparatus of the invention advantageously minimize the formation and entrapment of gas pockets against the quenched surface during the casting of the strip.
  • the invention avoids the needs for complex vacuum casting apparatus and can be practiced in an ambient atmosphere.
  • the exothermic reaction of the reducing gas in the depletion region surprisingly provides better and more uniform cooling and quenching of the molten metal.
  • Heat resulting from the exothermically reacting gas provides a low density reducing atmosphere that inhibits the formation of gas pockets which operate to decrease contact between the molten metal and the quench surface.
  • the more uniform quenching provides improved physical properties in the cast strip.
  • the reduction of surface defects on the quenched surface side of the strip increases the packing factor of the material and decreases localized stress concentrations that can cause premature mechanical failure.
  • the smoothness of the free surface side of the cast strip i.e. the side not in contact with the quench surface of the chill body
  • This increased smoothness further increases the packing factor of the material.
  • the more uniform quenching afforded by the low density reducing atmopshere provides a more consistent and uniform formation of the amorphous state.
  • manufacture of strip composed of magnetic material the number and size of strip surface discontinuities is reduced, improving the magnetic properties of the strip.
  • the reduction of entrapped gas pockets markedly increases the heat conductive contact between the molten metal and the quench surface.
  • Thicker strips of rapidly solidifed metal can be produced. Such thicker strip is desirable because it can be more easily substituted for materials conventionally used in existing commercial applications.
  • These thick strip components can, surprisingly, be provided by rapid solidification in a single quenching step in much less time with decreased cost.
  • the present invention effectively minimizes gas pocket defects on the strip surface which contacts the quench surface, and produces strip having a smooth surface finish and uniform physical properties.
  • Complex equipment and procedures associated with vacuum casting are eliminated.
  • the invention efficiently casts ultra thin as well as extra thick metal strip directly from the melt at lower cost and with higher yield. Such ultra thin and extra thick strips are especially suited for use in such applications as magnetic devices and can be substituted for conventional materials with greater effectiveness and economy.
  • a strip is a slender body the transverse dimensions of which are much smaller than its length.
  • a strip includes wire, ribbon, sheet and the like of regular or irregular cross-section.
  • the invention is suitable for casting metal strip composed of crystalline or amorphous metal and is particularly suited for producing metal strip which is rapidly solidified and quenched at a rate of at least about 10'°C/sec from a melt of molten metal.
  • Such rapidly solidified strip has improved physical properties, such as improved tensile strength, ductility and magnetic properties.
  • Fig. 1 shows a representative prior art device for rapidly casting continuous metal strip.
  • Molten metal alloy contained in crucible 2 is heated by a heating element 3.
  • Pressurization of the crucible with an inert gas forces a molten stream through a nozzle 4 at the base of the crucible and deposits the molten metal onto a moving chill body, such as rotatable casting wheel 1.
  • Solidified moving strip 6, after its break-away point from the quench wheel is then routed onto a suitable winding means.
  • Quench surface 5 is preferably a material having high thermal conductivity. Suitable materials include carbon steel, stainless steel and copper based alloys such as beryllium-copper. To achieve the quench rates of at least about 10 4o C per second, wheel 1 is internally cooled and rotated to provide a quench surface that advances at a speed ranging from about 100-4000 meters per minute. Preferably, the quench surface speed ranges from about 200-3000 meters per minute. Typically, the thickness of the cast strip ranges from 25-100 microns (micrometers).
  • Fig. 2 shows a representative apparatus of the invention.
  • a moving chill body such as endless casting belt 7, has a chilled casting quench surface 5.
  • Nozzle means such as nozzle 4, deposits a stream of molten metal onto a quenching region 14 of quench surface 5 to form strip 6.
  • Nozzle 4 has an orifice 22 located at exit portion 26.
  • a depletion means including gas nozzle delivery means 8, and gas supply 12, supplies a reducing gas 24 from gas supply 12 to a depletion region located adjacent to and upstream from quenching region 14. The reducing gas reacts exothermically within the depletion region 13, providing a low density reducing atmosphere therewithin.
  • Nozzle 8 is suitably located to direct reducing gas 24 at and around depletion region so that the reducing gas 24 substantially floods the depletion region 13.
  • Valve 16 regulates the volume and velocity through nozzle 8.
  • gas nozzle 8 is located upstream of quenching region 14 and is directed substantially normal to the direction of movement of the quench surface.
  • gas nozzle 8 can be located coaxial with casting nozzle 4 as representatively shown in Fig. 3.
  • low density reducing atmosphere means a reducing atmosphere having a gas density less than 1 gram per liter and preferably, having a gas density of less than about 0.5 grams per liter.
  • gas 24 is exothermically reacted to at least about 800 K, and more preferably, is exothermically reacted to at least about 1300 K.
  • hotter reducing gases are preferred because they will have lower densities and will better minimize the formation and entrapment of gas pockets between quench surface 5 and the deposited molten metal.
  • Entrapped gas pockets are undesirable because they produce ribbon surface defects that degrade the surface smoothness. In extreme cases, the gas pockets will cause perforations through strip 6.
  • a very smooth surface finish is particularly important when winding magnetic metal strip to form magnetic cores because surface defects reduce the packing factor of the material.
  • the packing factor is the volume fraction of the actual magnetic material in the wound core (the volume of magnetic material divided by the total core volume) and is often expressed in percent.
  • a smooth surface without defects is also important in optimizing the magnetic properties of strip 6 and in minimizing localized stress concentrations that would otherwise reduce the mechanical strength of the strip.
  • Gas pockets also insulate the deposited molten metal from quench surface 5 and reduce the quench rate in localized areas.
  • the resultant, non-uniform quenching produces non-uniform physical properties in strip 6, such as non-uniform strength, ductility and magnetic properties.
  • gas pockets can allow undesired crystallization in localized portions of the strip.
  • the gas pockets and the local crystallizations produce discontinuities which inhibit mobility of magnetic domain walls, thereby degrading the magnetic properties of the material.
  • the invention produces high quality metal strip with improved surface finish and improved physical properties.
  • metal strip has been produced with packing factors of at least about 80%, and up to about 95%.
  • the mechanism by which gas pockets are reduced can be more readily explained with reference to Fig. 6.
  • the gas boundary layer velocity profile near quench surface 5 and upstream of melt puddle 18 is shown schematically at 20.
  • the maximum gas boundary layer velocity occurs immediately adjacent to quench surface 5 (substrate) and is equal to the velocity of the moving quench surface.
  • moving quench surface 5 ordinarily draws cool air from the ambient atmosphere into depletion region 13 and into quenching region 14, the region of the quench surface upon which molten metal is deposited. Because of the drafting of relatively cool air into the quenching region, the presence of the hot casting nozzle and the molten metal do not sufficiently heat the local atmosphere to significantly reduce the density thereof.
  • Melt puddle 18 wets the substrate surface to an extent determined by various factors including the metal alloy composition, the substrate composition, and the presence of surface films.
  • the pressure exerted by the gas boundary layer at the melt-substrate interface acts to locally separate the melt from the substrate and form entrained gas pockets which will appear as "lift-off" areas 44 on the ribbon underside.
  • the stagnation pressure of the gas boundary layer pressure if the layer hit a rigid wall
  • the boundary layer gas density is reduced by exothermically reacting a reducing gas. As the exothermic reaction of the reducing gas proceeds, heat provided by the reaction causes the density of the gas to diminish as the inverse of the absolute temperature. By exothermically reacting a reducing gas in depletion region 13 at the upstream side of the melt puddle 18, the size and the number of entrained gas pockets under the melt puddle can be substantially reduced.
  • heat produced by the low density reducing gas atmosphere located proximate to quenching region 14 does not degrade the quenching of the molten metal. Rather, heat produced by the reduction reaction actually improves the uniformity of the quench rate by minimizing the presence of insulating, entrapped gas pockets, and thereby improves the quality of the cast strip.
  • Suitable reducing gases include carbon monoxide gas and gas mixtures therewith.
  • a reducing atmosphere minimizes the oxidation of strip 6.
  • the reducing atmosphere starves quench surface 5 of oxygen and minimized the oxidation thereof.
  • the reduced oxidation improves the wettability of the quench surface and allows molten metal to be more uniformly deposited on quench surface 5.
  • the reduced oxidation renders the quench surface much more resistant to thermally induced fatigue crack nucleation and growth.
  • the reducing atmosphere also depletes oxygen from the region of nozzle 4 thereby reducing the clogging of nozzle orifice 22, particularly clogging due to oxide particulates.
  • additional gas nozzle 32 may be employed to provide additional reducing gas atmospheres along selected portions of strip 6, as representatively shown in Fig. 2.
  • Fig. 4 shows an embodiment of the invention wherein the reducing gas is capable of being ignited and burned to form a reducing flame atmosphere.
  • Nozzle 4 deposits molten metal onto quench surface 5 of rotating casting wheel 1 to form strip 6.
  • the depletion means in this embodiment is comprised of gas supply 12, gas nozzle 8 and ignition means 30.
  • Valve 16 regulates the volume and velocity of gas delivered through gas nozzle 8, and a wiper brush 42 conditions quench surface 5 to help reduce oxidation thereof.
  • ignition means 30 ignites the gas to produce a heated, low-density reducing atmosphere around depletion region 13 and around quench surface region 14 where molten metal is deposited.
  • Suitable ignition means include spark ignition, hot filament, hot plates and the like.
  • the hot casting nozzle serves as a suitable ignition means which automatically ignites the reducing gas upon contact therewith.
  • the resultant flame atmosphere forms a flame plume 28 which begins upstream of quenching region 14 and consumes oxygen therefrom.
  • unburned reducing gas within the plume reacts to reduce the oxides on quench surface 5, nozzle 4 and strip 6.
  • the visibility of flame 28 allows easy optimization and control of the gas flow, and plume 28 is effectively drawn around the contour of wheel 1 by the wheel rotation to provide an extended reducing flame atmosphere.
  • a hot reducing atmosphere is located around quenching surface 14 and for a discrete distance thereafter.
  • the extended flame plume ⁇ advantageously provides a non-oxidizing, protective atmosphere around strip 6 while it is cooling.
  • additional gas nozzles 32 and ignition means 34 can be employed to provide additional reducing flame plumes 36 along selected portions of strip 6 to further protect the strip from oxidation.
  • a further advantage provided by the hot, reducing flame plume is that the smoothness of the free surface side of the strip (the side not in contact with the quench surface) is significantly improved. Experiments have shown that the mean roughness of the rapidly solidified metal strip, as measured by standard techniques such as pack factor, is significantly reduced when the strip is produced in the reducing flame plume of the invention.
  • the combustion product of the burned gas should not produce a liquid or solid phase which could precipitate onto quench surface 5 or nozzle 4.
  • hydrogen gas has been unsatisfactory under ordinary conditions because the combustion product is water which condenses onto quench surface 5.
  • the hydrogen flame plume does not adequately reduce the formation of gas pockets on the quench surface side of strip 6.
  • the reducing gas 24 is carbon monoxide (CO) gas, that will not only burn and consume oxygen in a strongly exothermic reaction, but will also produce combustion products that will remain gaseous at casting conditions and also provides a desirable, anhydrous, reducing atmosphere.
  • CO carbon monoxide
  • a reducing flame atmosphere provides an efficient means for heating the atmosphere located proximate to melt puddle 18 to very high temperatures, in the order of 1300-1500 K. Such temperature provide very low gas densities around the melt puddle 18. The high temperatures also increase the kinetics of the reduction reaction to further minimize the oxidation of quench surface 5, nozzle 4 and strip 6. The presence of a hot reducing flame at nozzle 4 also reduces thermal gradients therein which might crack the nozzle.
  • the embodiment of the invention employing a reducing flame atmosphere more efficiently produces a heated, low-density reducing atmosphere around quench surface 5 which improves the smoothness of both sides of the cast strip and more effectively prevents oxidation of quench surface 5, strip 6 and casting nozzle 4.
  • Rapid quenching employing conditions described heretofore can be used to obtain a metastable, homogeneous, ductile material.
  • the metastable material may be glassy, in which case there is no long range order.
  • X-ray diffraction patterns of glassy metal alloys show only a diffuse gur, similar to that observed for inorganic oxide glasses.
  • Such glassy alloys must be at least 50% glassy to be sufficiently ductile to permit subsequent handling, such as stamping complex shape from ribbons of the alloys.
  • the glassy metal alloy must be at least 80% glassy, and most preferably substantially (or totally) glassy, to attain superior ductility.
  • the metastable phase may also be a solid solution of the constituent elements.
  • such metastable, solid solution phases are not ordinarily produced under conventional processing techniques employed in the art of fabricating crystalline alloys.
  • X-ray diffraction pattersn of the solid solution alloys show the sharp diffraction peaks characteristic of crystalline alloys, with some broadening of the peaks due to desired fine-grained size of crystallites.
  • Such metastable materials are also ductile when produced under the conditions described above.
  • the material of the invention is advantageously produced in foil (or ribbon) form, and may be used in product applications as cast, whether the material is glassy or a solid solution.
  • foils of glassy metal alloys may be heat treated to obtain a crystalline phase, preferably fine-grained, in order to promote longer die life when stamping of complex shapes is contemplated.
  • the invention may optionally include a flexible hugger belt 38 which entrains strip 6 against quench surface 5 to prolong cooling contact therewith.
  • the prolonged contact improves the quenching of strip 6 by providing a more uniform and prolonged cooling period for the strip.
  • Guide wheels 40 position belt 38 in the desired hugging position along quench surface 5, and a drive means moves belt 38 such that the belt portion in hugging relation to quench surface 5 moves at a velocity substantially equal to the velocity of the quench surface:
  • belt 38 overlaps the marginal portions of strip 6 to directly contact and frictionally engage quench surface 5. This frictional engagement provides the required driving means to move the belt.
  • a further advantage of thin strip is that the strip experiences less bending stresses when wound to a given diameter. Excessive bending stresses will degrade the magnetic properties through the phenomenon of magnetostriction.
  • the apparatus and method of the invention are particularly useful for forming very thin metal strip. Since the invention significantly reduces the size and depth of gas pockets defects, there is less chance that such a defect will be large enough to perforate the cast strip. As a result, very thin strip can be cast because there is less probability that a defect large enough to perforate the strip will form.
  • the invention can be adapted to cast very thin metal strip, which as-cast, is less than about 15 micrometers thick.
  • the cast strip has a thickness of 12 micrometers or less. More preferably, the cast strip thickness ranges from 7 to 12 micrometers.
  • the thin metal strip has a width dimension which measures at least about 1.5 millimeters, and preferably measures at least about 10 mm.
  • a forced-convection-cooled, casting wheel having a plain carbon steel substrate was used to prepare nickel-base and iron-base glassy metal ribbons.
  • the casting wheel had an internal cooling structure similar to that described in US-A-4,307,771, a diameter of 38 cm and a width of 5 cm. It was rotated at a speed of 890 rpm, corresponding to a circumferential surface velocity of 18 m/s.
  • the substrate was conditioned continuously during the run by an idling brush wheel inclined about 10° out of the casting direction.
  • a nozzle having a slotted orifice of 0.4 millimeter width and 25 millimeter length defined by a first lip and a second lip each having a width of 1.5 millimeters (lips numbered in direction of rotation of the chill roll) was mounted perpendicular to the direction of movement of the peripheral surface of the casting wheel, such that the gap between the second lip and the gap between the first lip and the surface of the casting wheel was .20 millimeter.
  • Nickel-base metal alloy having composition Ni 68 Cr,Fe 3 B ll Si 8 (subscripts in atomic percent) with a melting point of about 1000°C was supplied to the nozzle from a pressurized crucible, the metal within the crucible being maintained under pressure of about 3.5 psig (24 kPa) at temperature of 1300°C. Pressure was supplied by means of an argon blanket. The molten metal was expelled through the slotted orifice at the rate of 6.6 kilograms per minute. It solidified on the surface of the chill roll into a strip of 0.033 millimeter thickness having width of 2.54 cm. Upon examination using X-ray diffractometry, the strip was found to be amorphous in structure. The ribbon showed significant populations of entrapped air pockets in the underside. A dark oxidation track formed on the substrate surface during ribbon casting, limiting the ribbon substrate adhesion.
  • Example I The procedure of Example I was repeated, employing the equipment, process conditions, metal and alloys used in Example I except that a carbon monoxide flame was directed at the ribbon casting track upstream of the melt puddle to reduce oxidation and promote ribbon-substrate adhesion.
  • the combined actions of the flame and the conditioning brush reduced the substrate oxidation, increased adhesion and produced ribbon having good geometric uniformity.
  • the best results were obtained when the distance between the carbon monoxide flame and the back of the melt puddle was less than about 2 cm ( ⁇ 1 inch).
  • Tensile specimens cut from the strip in longitudinal and transverse direction exhibited equal tensile strength and elongation. The strip had isotropic tensile properties.
  • Example I The procedure of Example I was repeated, employing the equipment, process conditions metal and alloy summarized in the Table I below to obtain the product described herein.
  • the iron-base ribbon was annealed in an inert gas atmosphere for 2 hours at a temperature of 365°C in a field of 80 amperes/meter applied longitudinal of the ribbon length.
  • FIG. 7A-B A photomicrograph showing the underside of the iron-base, amorphous ribbon is depicted in Figs. 7A-B. Note that the included air pockets shown are rather large and elongated.
  • Example III The procedure of Example III was repeated employing the same equipment, process conditions and alloy except that a carbon monoxide flame was directed at the ribbon casting track upstream of the melt puddle to reduce oxidation and promote ribbon substrate adhesion.
  • a photomicrograph showing the underside of the iron-base amorphous ribbon produced using the carbon monoxide flame is depicted in Figs. 8A-B. Note the significant reduction in included air pockets on the underside of iron-base ribbon cast using the carbon monoxide flame as compared with those shown in Figs. 7A-B. Magnetic properties of the ferromagnetic ribbons as well as the pack factor thereof were also improved (see Table II below). Similar improvements in the underside of nickel-base amorphous ribbon have also been observed.
  • Table I illustrates the advantages of the present invention.
  • the ribbon cast in air (sample 1) was made by the casting procedure taught in US-A-4,142,571. Note the relatively low pack factor and magnetization loop squareness in both the as-cast and annealed states. Ribbons of various thicknesses made using the teachings of the present invention (samples 2-4) have much improved pack factors and magnetization loop squareness in both the as-cast and annealed states.
  • Sample 5 illustrates ribbon properties which result from casting in a flame atmosphere that produces non-gaseous combustion products (water, in this case). The occurrence of poor melt wetting in the manufacture of sample 5 has resulted in the inferior properties measured.

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Claims (7)

1. Vorrichtung zum Gießen von Metallstreifen mit einem sich bewegenden Kühlkörper (1) mit einer Abschreckoberfläche (5), einer Düseneinrichtung (4) zur Ablagerung eines Stromes von geschmolzenem Metall auf einem Abschreckbereich dieser Oberfläche unter Bildung des Streifens und einer Gaszufuhreinrichtung (12), dadurch gekennzeichnet, daß die Gaszufuhreinrichtung (12), die als eine Kohlenmonoxidquelle wirkt, einen Teil einer Abreicherungseinrichtung bildet, die auch eine nahe der Düseneinrichtung (4) und aufstromwärts von dieser gelegene Zuführungseinrichtung (8) einschließt, um Kohlenmonoxid (24) zu einem Abreicherungsbereich (13) nahe dem Abschreckbereich (14) und aufstromwärts von diesem zuzuführen, um eine reduzierende Atmosphäre niedriger Dichte in dem Abreicherungsbereich (13) durch exotherme Reaktion des Kohlenmonoxids zu erzeugen.
2. Vorrichtung nach Anspruch 1, zusätzlich mit einer Zündeinrichtung (30) zum Zünden des Kohlenmonoxids, um eine reduzierende Flammenatmosphäre in dem Abreicherungsbereich zu erzeugen.
3. Vorrichtung nach Anspruch 1, zusätzlich mit einer Einrichtung (32) zur Lieferung wenigstens einer zusätzlichen reduzierenden Atmosphäre, die aus einem zweiten reduzierenden Gas besteht und entlang einem Teil des Streifens angeordnet ist.
4. Vorrichtung nach Anspruch 3, zusätzlich mit einer Zündeinrichtung (34) zum Zünden des zweiten reduzierenden Gases, um eine zusätzliche reduzierende Flammenatmosphäre entlang einem ausgewählten Bereich des Streifens zu erzeugen.
5. Vorrichtung nach Anspruch 1, zusätzlich mit einem flexiblen Andrückband (38), das den Streifen gegen die Abschreckoberfläche (5) gedrückt mitnimmt, um die Berührung zwischen ihnen zu verlängern.
6. Verfahren zum Gießen von Metallstreifen mit den Stufen, in denen man einen Kühlkörper (1) mit einer Abschreckoberfläche (5) mit einer ausgewählten Geschwindigkeit bewegt, einen Strom von geschmolzenem Metall auf einem Abschreckbereich (14) der Abschreckoberfläche unter Bildung des Streifens ablagert und ein Gas dem Kühlkörper zuführt, dadurch gekennzeichnet, daß man ein reduzierendes Gas einem Abreicherungsbereich (13), der nahe dem Abschreckbereich (14) und aufstromwärts von diesem liegt, zuführt und exotherm umsetzt, um seine Dichte zu vermindern und eine reduzierende Atmosphäre geringer Dichte in dem Abreicherungsbereich zu erzeugen.
7. Verfahren nach Anspruch 6, dadurch gekennzeichnet, daß als reduzierendes Gas Kohlenmonoxidgas entlang einem Abschnitt des Streifens zugeführt und gezündet wird, um eine reduzierende Flammenatmosphäre entlang diesem Streifenabschnitt zu erzeugen.
EP19840101458 1983-04-11 1984-02-13 Giessen in exothermer reduzierender Atmosphäre Expired EP0121683B1 (de)

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US48347383A 1983-04-11 1983-04-11
US483473 1983-04-11
US49092283A 1983-05-02 1983-05-02
US490922 1990-03-09

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EP0121683B1 true EP0121683B1 (de) 1989-04-26

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AU (1) AU2402084A (de)
CA (1) CA1214619A (de)
DE (1) DE3477894D1 (de)
HK (1) HK10191A (de)
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GB519977A (en) * 1938-08-22 1940-04-11 Joseph Marcel Merle Improvements in or relating to a method of making flat metallic products
US3861450A (en) * 1973-04-06 1975-01-21 Battelle Development Corp An improved method of formation of filament directly from molten material
US3895673A (en) * 1974-07-31 1975-07-22 Jones & Laughlin Steel Corp Gas cover for casting machine
GB1526192A (en) * 1975-09-19 1978-09-27 British Steel Corp Continuous casting of metal strip
US4177856A (en) * 1978-08-28 1979-12-11 General Electric Company Critical gas boundary layer Reynolds number for enhanced processing of wide glassy alloy ribbons

Also Published As

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SG10191G (en) 1991-04-05
DE3477894D1 (en) 1989-06-01
HK10191A (en) 1991-02-08
EP0121683A1 (de) 1984-10-17
CA1214619A (en) 1986-12-02
AU2402084A (en) 1984-10-18

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