US3655837A - Process for producing metal powder - Google Patents

Process for producing metal powder Download PDF

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US3655837A
US3655837A US834368A US3655837DA US3655837A US 3655837 A US3655837 A US 3655837A US 834368 A US834368 A US 834368A US 3655837D A US3655837D A US 3655837DA US 3655837 A US3655837 A US 3655837A
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particles
metal
powder
atomizing
nozzle
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William A Reed
William K Kinzer
John J Swanson
Robert E Kusner
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Ltv Steel Co Inc
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Republic Steel Corp
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Assigned to LTV STEEL COMPANY, INC., reassignment LTV STEEL COMPANY, INC., MERGER AND CHANGE OF NAME EFFECTIVE DECEMBER 19, 1984, (NEW JERSEY) Assignors: JONES & LAUGHLIN STEEL, INCORPORATED, A DE. CORP. (INTO), REPUBLIC STEEL CORPORATION, A NJ CORP. (CHANGEDTO)
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
    • B22F9/00—Making metallic powder or suspensions thereof
    • B22F9/02—Making metallic powder or suspensions thereof using physical processes
    • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
    • B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
    • B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid

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  • the present invention relates to a process for producing metal powder.
  • the invention involves the manufacture and preparation of metal powder by injecting an inert gas or fine particles of metal powder into the flow of molten metal and/or into the flow of metal particles formed by the atomization of molten metal.
  • atomization is a process which involves the disintegration of a stream of molten metal into individual droplets which are subsequently solidified.
  • An atomizing jet of fluid e.g., water, air or inert gas, is directed toward the molten stream in order to break up the stream into fine particles, which are cooled and solidified.
  • the resulting particles may contain an oxide inclusion and have an oxide coating on their outer surface.
  • inert gas is used as the atomizing fluid, the particles formed may have a regular spherical shape which does not lend itself to good compaction of the powder.
  • Water will produce the desired irregularly shaped particles, the high oxide content of the product negates this advantage.
  • the hot particles formed by inert gas atomization which accumulate on the bottom of the atomization chamber form a sintered mass or cake which must then 'be' ground to obtain particles of usable size for subsequent consolidation into a compacted product. Frequently, the sintered mass or cake is not suificiently friable to be readily ground without destruction of basic particle shapes. It is therefore desirable to provide a process which efliciently produces a metal powder suitable for subsequent compaction.
  • An object of the present invention is to provide a method for atomizing molten metal into a powder comprised of particles of irregular shape'and lacking an oxide coating. It is another object of the invention to produce a metal powder which agglomerates but which can be readily ground into particles having optimum compacting properties. Still another object is to dissipate sufficient heat from the atomized metal to prevent fusion of the particles before they can be collected from the base of the atomizing chamber.
  • the instant invention contemplates the process of forming a flowing stream of molten metal, e.g., low-carbon, aluminum-killed, draw- 3,655,837 Patented Apr. 11, 1972 ing-quality steel, directing an atomizing inert gas into an atomizing zone against the metal to produce particles, injecting matter against the particles prior to atomizatlon and/or after they emerge from the atomizing zone to agglomerate them into irregular shapes and to cool the particles, and collecting the particles in a collecting zone.
  • molten metal e.g., low-carbon, aluminum-killed, draw- 3,655,837 Patented Apr. 11, 1972 ing-quality steel
  • the molten metal is poured from a ladle into a tundish, which causes a smooth steady stream of molten metal to be introduced into an atomizing chamber.
  • an inert atomizing gas is directed against the molten metal in an atomizing zone to separate the molten stream into discrete particles.
  • the gas is directed toward the molten stream by an annular nozzle means, e.g., a single annular nozzle or a series of jets annularly disposed about the flow of molten metal and constituting a nozzle, which may be of the converging-diverging type to produce a stream of gas which leaves the nozzle .at supersonic velocity.
  • An included gas angle of about 10 to 12 is desirableto prevent the nozzle from clogging if a converging-diverging type of annular nozzle is employed, but an included gas angle of less than 40 is preferable when separate convergingdiverging jets annularly spaced are used.
  • the gas pressure should be about to pounds per square inch and the gas should flow at a rate of about 1200 cubic feet per minute for a molten flow of 150 pounds per minute.
  • the diameter of the nozzle (the diameter of the annulus defined by either a single annular pipe or the like forming a nozzle or a series of annularly disposed jets forming a nozzle) is preferably about three to four times the diameter of the molten metal stream.
  • This injected matter may be either an inert gas or fine particles of powder, e.g., as produced from atomlzation and recirculated, or both inert gas and powder. If inert gas is employed, it may be directed toward the part1- cles between the atomizing and collecting zones of the atomizing chamber in a direction substantially transverse to or against the flow of particles. It fine particles of powder are employed, the particles may be contained in a hopper and directed toward or with the flow of molten metal or atomized particles by a nozzle or an impeller. The ratio of injected fine particles to atomized molten metal is preferably about 1:1 by weight.
  • Means including a conveyor are provided near the base of the atomizing chamber for collecting the produced powder before it can become sintered or caked.
  • a rotary cooler may also be employed near the base of the atomizing chamber.
  • FIG. 1 is an elevational view, partly in section, of representative apparatus for carrying out the present invention.
  • FIG. 2 is an enlarged partial view of one form of atomizing nozzle useful in the invention.
  • FIG. 3 is an enlarged sectional view of another form of atomizing nozzle used in the invention.
  • FIG. 4 is a partial sectional view of still another form of atomizing nozzle used in the instant invention.
  • FIG. 5 is a broken view of another form of apparatus used in the invention.
  • FIG. 6 is a broken view of still another form of apparatus used in the invention.
  • FIG. 7 is a broken view of a further modification of the apparatus.
  • FIG. 8 is a broken view of yet another embodiment of apparatus useful in carrying out the invention.
  • FIG. 9 is a perspective view of a means for removing metal powder from the atomizing chamber useful in the present invention.
  • FIG. 1 of the drawings there is shown representative atomizing apparatus 10 for carrying out the present invention.
  • the apparatus includes a tundish 12 for receiving molten metal, e.g. low carbon, aluminumkilled, drawing-quality steel (termed herein AKDQ steel), discharged from a ladle 14 and providing a smooth flowing stream of molten metal.
  • a tundish 12 for receiving molten metal, e.g. low carbon, aluminumkilled, drawing-quality steel (termed herein AKDQ steel), discharged from a ladle 14 and providing a smooth flowing stream of molten metal.
  • an atomizing chamber 16 having an atomizing zone 16a into which the stream of molten metal from the tundish 12 flows for the purpose of atomization of the metal into powder.
  • a collecting zone 16b within the chamber 16 receives the produced powder.
  • an atomizing nozzle 20 Disposed within the atomizing chamber 16 is an atomizing nozzle 20 for directing an atomizing gas against the stream of molten metal to atomize the metal into powder.
  • a series of secondary nozzles -22 is provided for injecting additional matter into the chamber 16 against the fiow of molten metal and/or the produced metal powder in order to agglomerate and cool the metal powder so that it is suitable for further processing into metal plate, sheeet, or strip, for example.
  • molten metal contained within the ladle 14 is preheated to a suflicient temperature to ensure proper pouring.
  • the molten metal is lates the flow of molten metal from the ladle 14 into the tundish 12, which should be heated to a temperature of about 2800" F. prior to pouring (in the case of AKDQ steel) in order to prevent a frozen melt.
  • the tundish regulates the flow of molten mteal from the ladle 14 into the atomizing chamber 61.
  • the tundish 12 may be fabricated from a refractory material, eg alumite (93% A1 which has been cast in a mold and fired slowly to about 2400" lF., e.g., prior to use. Although a tundish 12 having one feeding nozzle is illustrated, it is possible to employ a tundish which will provide multiple streams of molten metal.
  • a refractory material eg alumite (93% A1 which has been cast in a mold and fired slowly to about 2400" lF., e.g., prior to use.
  • an inlet pipe 24 for allowing an inert gas, e.g. nitrogen gas, to be introduced into the tundish.
  • This inert gas pre'vents oxides from forming in the molten metal prior to atomization.
  • the atomizing chamber 16 should also be purged with inert gas for about a thirtyminute period prior to atomization at a gas flow rate of about 190 cu. ft. per minute for a chamber volume of about 315 cu. ft. This inert gas atmosphere reduces oxidation of the produced metal particles.
  • the molten metal After the molten metal has been formed by the tundish 12 into a smooth flowing steady stream, it is permitted to enter the atomizing zone 16a of the atomizing chamber 16 when the molten metal at a temperature of about 2950 3000 F. is transformed into metal particles by means of a stream of inert gas, e.g. nitrogen preferably of about 99.995 purity, directed downwardly from an atomizing gas exit zone 20b against the molten metal stream by atomizing nozzle 20. If a nozzle 20 of the converging-diverging type is employed to create a supersonic flow of gas, the gas exit zone.
  • inert gas e.g. nitrogen preferably of about 99.995 purity
  • the atomizing nozzles have been shown schematically and are designated 120.
  • the nozzle should provide an included gas angle (designated 20:: in FIG. 1) with the orientation of each port of the nozzle at an angle from the vertical equal to one-half the included gas angle and directed toward the central axis of the atomizing nozzle.
  • the gas from the nozzle atomizes the molten stream of metal into particles of (fine size, which thereafter cool and which may be collected at the bottom of the atomizing chamber 16.
  • An atomizing gas pressure of about to lbs. per square inch with a flow rate of about 1200 to 1500 cu. ft. per minute for a molten metal flow of about 150 pounds per minute or about 8 to 10 cu. ft. of gas per pound of molten metal acted upon is preferred.
  • Lower gas pressures produce extremely coarse particles which form a sintered mass at the bottom of the atomizing chamber 16 (due to heat retention in the particles), while higher gas pressure in combination With a high included gas angle (20a in FIG.
  • the diameter of the atomizing nozzle be approximately three to four times the diameter of the molten metal stream flowing from the tundish in order to reduce the pressure within the nozzle and the tendency of the metal particles to strike back at the nozzle.
  • FIGS. 2 through 4 show various forms of atomizing nozzles which may be used to direct the inert gas against the stream of molten metal.
  • the atomizing nozzle comprises an annular pipe 26 associated with a source of inert gas through an inlet pipe 27.
  • the annular pipe 26 may alternatively be comprised of quadrants separated by partitions (not shown); in that case, four inlet pipes 27 would be required to supply inert gas to the nozzles.
  • a number of gas jets 28 are disposed equally about the perimeter of the annular pipe 26.
  • Each gas jet 28 is oriented at a suitable angle from the vertical (up to 20, for an included gas angle of up to 40) and points toward the central axis of the annular pipe 26 such that the series of gas jets 28 circumscribes the stream of molten metal and the gas cone therefrom intersects the stream at a distance from the nozzle within the atomizing zone 16a of the atomizing chamber 16.
  • the optimum dimensions for a series of gas jets 28 have been found to be an included gas angle of about 30 and a nozzle effective diameter of about 3 /2 in. for a molten stream of metal approximately in. in diameter. Ungrindable coarse material is at a minimum when the effective diameter of the jets 28 is that value.
  • each gas jet 28 may be formed from copper tubing (28a) or the like and may be flexible so that the included gas angle and effective diameter of the nozzle might be easily adjusted by bending the tubing.
  • the gas jets 28 may be provided with a ball-and-socket connection so that the angle of the jets may be easily varied. It is preferred that each jet 28 be of the converging-diverging type so that the gas may exit from the jets at supersonic velocity, as described in more detail below in conjunction with the discussion of the nozzle shown in FIG. 4.
  • FIG. 3 there is shown a conventional atomizing nozzle comprising a housing 29 defining an annular internal chamber 29a associated with a source of inert gas through an inlet pipe 31.
  • This nozzle has an annular orifice 32 or series of small apertures for directing the inert gas toward the stream of molten metal which passes through an opening 34 in the center of the nozzle.
  • the internal diameter of the annular orifice 32 be approximately 3 inches when the diameter of the molten stream of metal is approximately W of an inch, as this tolerates to a greater extent misalignment of the tundish 12 and wandering of the stream of molten metal.
  • annular orifice 32 comprising an annulus of about 0.02 to 0.04 inches is suitable for atomization, unless a high inert gas pressure can be maintained in which case the annular opening may be increased.
  • a nozzle has the disadvantage of clogging within a relatively short time due to striking back of the metal particles against the nozzle, especially when the included gas angle exceeds.
  • FIG. 4 of the drawings there is shown a portion of an annular atomizing nozzle similar to the nozzle shown in FIG. 3 but having an annular orifice 32a of the converging-diverging type.
  • Such a nozzle includes a restriction 3212 within the annular orifice 32a in order to produce a flow of inert gas which exits the nozzle at the gas exit zone b at supersonic velocity.
  • An atomizing nozzle possessing the characteristic of supersonic flow is desirable in that it permits more effective usage of the inert gas needed to atomize the stream of molten metal. It is preferred that such a nozzle have an included gas angle of about 10 to 12, when a gas pressure of 100 to 150 lbs. per square inch is employed, in order to prevent clogging of the nozzle.
  • the other dimensions of the nozzle are the same as those for the nozzle shown in FIG. 3.
  • a converging-diverging type nozzle may produce a metal powder of intermediate size, e.g. 10/ +65 mesh, with a lesser amount of fine and coarse material.
  • T absolute stagnation temperature (in chamber 30)
  • T absolute temperature at any given location in the nozzle
  • P stagnation pressure (in chamber 30)
  • p gas density at any given location in the nozzle
  • A area at any given location in the nozzle
  • k ratio of specific heats (specific heat of gas at constant pressure divided by specific heat at constant volume)
  • M Mach number.
  • Equation 4 may be employed to determine the area at the nozzle exit for any given nozzle throat area and desired Mach number at the nozzle exit.
  • One important feature of the invention is that before and/or after the molten metal has been atomized into particles within the atomizing zone 16a of the atomizing chamber 16, additional matter is injected into the atomizing chamber 16 in order to cause the particles to agglomerate into particles of irregular and varied shape and to cool the metal particles to prevent them from forming a sintered mass.
  • the additional injected matter may take the form of, e.g., an inert gas such as nitrogen gas preferably of 99.995% purity or fine particles of powder produced from atomization, preferably by recirculating fine particles separated from the main mass of atomized particles.
  • This additional matter is injected into the atomizing chamber 16 and directed into the flow of metal particles through a series of secondary nozzles 22a through 2.2g in the drawings.
  • Inert gas e.g., nitrogen gas
  • injected into the flow of metal particles at a pressure of about 30 pounds per square inch has been found effective to agglomerate the particles so that they are of the optimum shape for compacting into metal plate, sheet or strip.
  • the inert gas may be injected into the atomizing chamber 16 through a valve 36 and a plurality of secondary nozzles 22a penetrating into the interior of the chamber 16 and directed substantially transverse to the flow of metal particles, as shown in FIG. 1.
  • Inert gas may also be directed substantially upwardly and against the flow of metal particles through 22b (as shown in FIG.
  • the gas also redirects any fine material dissipating from the flow of metal particles or accumulating in the collecting zone 16b back toward the flowing stream.
  • Most of the agglomeration caused by the inert gas occurs with coarse particles rather than with fine particles, since the latter cool more rapidly by virtue of a higher surface area per unit mass and hence are not subject to agglomeration.
  • Atomized powder injected with additional inert gas has been found to be of a lower density and to flow at a slower rate than powder produced without the injection of additional inert gas. Thus the powder so produced is particularly suitable for further processing.
  • Injection of fine particles of powder into the stream of metal particles results in more agglomeration of the latter as well as helps to cool the particles, and hence reduces the amount of tightly sintered material formed at the bottom of the atomizing chamber 16, increasing the yield of metal powder.
  • a product compacted from agglomerated particles has high strength.
  • This fine powder is advantageously obtained by collecting the particles which leave the chamber 16 through an inert gas exhaust vent 37 near the atomizing zone 16oz of the chamber 16, the particles being recirculated at ambient temperature.
  • the additional powder which may be contained in a plurality of hoppers 38, may be injected into the stream of metal particles by means of a plurality of secondary nozzles 220 coupled to the hoppers 38 and penetrating into the atomizing chamber 16, oriented so that the powder flow intersects the stream of metal particles at a point beneath the atomizing zone.
  • Impellers 40 may be employed to direct the injected fine material into the stream of particles in a subsantially transverse direction.
  • the preferred amount of recirculated fine powder is about 400-600 pounds for a 500 pound charge of molten metal, or a ratio of about 1 part of fine to 1 part of molten metal, but a ratio of about 1.3 produces the lowest amount of sintered mass or cake.
  • the embodiment of the apparatus shown in FIG. 1 produces few large particles which are ungrindable into usable powder. But the injection of fine particles of powder results in a more coarse product than when no secondary matter is injected. When no secondary powder is injected, only an ungrindable sintered mass and loose atomized powder are produced, whereas the addition of the injected matter results in a grindable sintered mass or cake which when ground may be combined with the loose powder to effect a high yield.
  • the coarse product also contains a higher percentage of agglomerates than a fine product, thus resulting in a more usable product.
  • FIGS. 5-7 other apparatus may also be employed to introduce fine particles of powder into the stream of molten metal and/or metal particles.
  • fine particles of powder contained in the hopper 38 are discharged into streams of inert gas, e.g. nitrogen gas, which enter chamber 16 at a point beneath the atomizing zone 16a through nozzle 22d directed substantially transverse to the flow of metal particles.
  • inert gas e.g. nitrogen gas
  • Fine particles of powder contained within the hoppers 38 may also be injected directly into the stream of molten metal by means of a plurality of nozzles 22a before the metal has been atomized into particles in the atomizing zone 16a (as shown in FIG. 6).
  • This method produces the highest percentage of coarse particles, especially when the rate of flow of fine particles is increased.
  • the fine particles of powder cause the metal particles to agglomerate into particles of irregular and varied shape and to cool to prevent them from forming a sintered mass whether the fine particles are introduced prior to atomization (FIG. 6) or subsequent thereto (FIGS. 1 and 5).
  • a plurality of hoppers 38 similar to the hoppers utilized in the above-mentioned embodiments discharge fine particles of powder toward the atomizing zone 16a of the chamber 16.
  • the fine particles are divided into two streams, one of which is directed by means of nozzle 22 toward the flow of molten metal before it has been atomized and the other of which is directed by means of nozzle 22g-toward the flow of metal particles after atomization.
  • Both streams of secondary particles are injected in the direction of flow of the molten metal and metal particle stream, so that the injection may be accomplished merely by a gravity feed, without the utilization of secondary nitrogen jets or impellers 40.
  • This method results in a less coarse powder than the method employing the apparatus of FIG. 6.
  • the particle size increases as more fine particles of powder are injected before atomization as opposed to post atomization, i.e. as the method more clearly approximates the device of FIG. 6. Greater control over particle size and extent of agglomeration is offered by the FIG. 7 apparatus.
  • zone of atomization might include a series of discrete gas sources spaced one from another in the general direction of movement of the stream of molten level so as to provide atomization at a number of levels.
  • atomizing gas could be directed not only from the nozzle but also from similar nozzle structures located as the nozzles 22 and 22g. Such a plurality of levels of atomizing might be useful for relatively large streams of molten metal, although the problem of nozzle clogging might be encountered.
  • fine particles of powder less than 65 mesh in size have been found most suitable for secondary injection.
  • This fraction of the product contains a relatively high percentage of spherical particles which, if subsequently compacted into steel plate, strip, or the like, results in an intermediate product of insufficient strength for further processing.
  • the use of the 65 mesh powder was effective to produce agglomerates, the amount of fines needed exceeded the amount generated.
  • Use of the more coarse product was particularly effective with the embodiment shown in FIG. 7.
  • the particles pass into the collecting zone 16b of the chamber 16. It has been found that the particles which settle in the relative center of the collecting zone 16b form a partially sintered prod uct, which when ground produces particles having a desired irregular shape. Thus the particles taken from the relative center of the collecting zone 16b are especially suited for compaction into metal plate, sheet, or strip.
  • the collecting zone 16b of the atomizing chamber 16 is shown associated with a rotary cooler 42.
  • the rotary cooler 42 may be utilized to transport the powder product to a station for further processing.
  • an enclosed container 44 may be provided, as shown in FIG. 9.
  • a container 44 defining a conveying device is presently preferable as it collects the produced powder before the particles become sintered or caked, which can readily occur as the powder enters the collecting zone 16b at a temperature of about 970 F.
  • Such a device 44 includes hopper plates 46 located at the base of the collecting zone 16b and adapted to discharge the produced metal powder onto a moving conveyor belt 48 enclosed by a housing 50.
  • the hopper plates 46 are inclined inwardly so that metal powder will more readily flow onto the conveyor belt 48.
  • the plurality of nozzles 52 may be provided for the injection of further inert gas, e.g. nitrogen gas, or fine particles of powder onto the hopper plates 46 to prevent the metal particles from adhering to the hopper plates and hindering the flow of material onto the conveyor belt 48.
  • a rotary cooler 42 or a conveyor belt 48 is an integral part of the invention as it provides in conjunction with the secondary injected matter a means for dissipating heat from the produced particles so that the particles do not form a sintered mass or cake.
  • EXAMPLE 1 In one operation of the process using auxiliary fine particles of metal powder and a device as shown in the upper portion of FIG. 1, an AKDQ steel was used to produce a metal powder, the steel having the following characteristics (given as percentages of the melt by Weight):
  • the atomizing chamber 16 (having a volume of approximately 315 cubic feet and formed from 12 feet of culvert sections 5 feet in diameter welded to a rectangular sheet container 5 x 4 x 3') was preliminary purged with nitrogen gas at the rate of 190 cubic feet per minute for about 30 minutes prior to atomization. During atomization the chamber 16 was maintained at a gas temperature of 250 to 300 F. and a pressure of 1.1 inches of water. 500 pounds of molten steel were discharged from the tundish 12 at a temperature of 3110" F. and at a rate of 180 pounds per minute through a -inch diameter feeding nozzle in the tundish.
  • a four-inch inside diameter nozzle comprising a plurality of gas jets 28 of the converging-diverging type (FIG. 2) with an included gas angle of 35 was employed to atomize the stream of molten steel into particles.
  • the atomizing inert gas was nitrogen gas of 99.995 purity and Was directed toward the stream at the rate of 1500 cubic feet per minute at a pressure of 130 pounds per square inch.
  • secondary fine particles of metal powder 65 mesh were injected into the stream of particles below the atomization zone by impellers such as impellers 40 in the amount of about 1.3 pounds of fine particles per pound of molten metal and at a rate of about 124 lbs. per min.
  • Atomized fines exited the atomizing chamber 16 through the inert gas exhaust vent 37. These fines made up 6.7% (by weight) of the product and contained 0.035% oxygen and 0.084% carbon.
  • the cumulative sieve analysis of the fines was as follows (in percent by weight).
  • the bulk of the atomized steel (48.8% by weight) was atomized directly into powder (excluding fines). 1.9% (by Weight) of this powder was +8 mesh in size and 98.1% was 8 mesh, that size being arbitrarily chosen to indicate ungrindable sinter.
  • the -8 mesh portion had a density of 3.72 grams per cubic centimeter and the following chemical composition (in percent by weight) Carbon 0.070 Aluminum 0.03 Manganese 0.26 Silicon 0.010 Phosphorus 0.003 Sulfur 0.017 Nitrogen 0.006 Oxygen 0.018
  • particles of AKDQ steel powder of the same chemistry of the steel of Example 1 were agglomerated and cooled.
  • the atomizing chamber 16 was of the same dimensions and was initially prepared in the same manner as explained in Example 1.
  • the molten steel was introduced into the atomizing chamber 16 at about the same parameters as disclosed in Example 1.
  • a 4-inch inside diameter nozzle comprising a plurality of gas jets 28 of the converging-diverging type (FIG. 2) with an included gas angle of 30 was employed to atomize the stream of molten metal into particles,
  • the atomizing inert gas was of the same type and flowed at about the same rate and pressure as the gas used in the process of Example 1.
  • Additional fine particles of metal powder (-65 mesh) were injected directly into the stream of molten metal by nozzles 22e prior to atomization in the amount of about 0.85 lb. of fine particles per pound of molten metal and at a rate of about 144 pounds per minute.
  • Examples 1 and 2 show that particle injection prior to atomization (Example 2) produces a coarser product than injection following atomization (Example 1).
  • EXAMPLE 3 Further operations of the process were conducted using apparatus such as shown in FIG. 7. Again an AKDQ steel having the characteristics of the first example was employed and the atomizing chamber 16 was of the same dimensions and was preliminarily prepared in the same manner. Moreover, 500 pounds of molten steel were again discharged from the tundish 12 at a temperature of about 3100 F. and at a rate of about 156 to 170 lbs. per minute through a -inch diameter feeding nozzle in the tundish. A 3-inch inside diameter nozzle comprising a plurality of gas jets 28 of the convergingdiverging type (FIG. 2) with an included gas angle of 30 was employed to atomize the stream of molten steel into particles.
  • FOG. 2 convergingdiverging type
  • the atomizing inert gas had about the same parameters as the inert gas used in the operation of Example 1. Secondary fine particles of metal powder were injected into both the stream of molten metal as by nozzles 22 (injected particles 65 mesh) and the stream of metal particles as by nozzles 22g (injected particles 65 mesh).
  • EXAMPLE 4 Using apparatus such as shown in FIG. 5 for introducing both secondary inert gas and fine particles of powder into the stream of produced metal particles, agglomeration and cooling of the particles resulted.
  • An AKDQ steel of about the same nature, in about the same amount, and flowing at about the same rate as that used in Example 1 was introduced into the atomizing chamber (which was prepared in the same manner indicated in Example 1).
  • the steel was atomized using a converging-diverging type nozzle (FIG. 2), the atomizing inert gas having about the aforementioned parameters of the first example. Additional fine particles of metal powder (65 mesh) were injected into the stream of metal particles after atomization in the amount of about 0.4 lb.
  • the fine particles of powder produced were similar in size to the particles produced in the above examples.
  • the cumulative sieve analysis (in percent by weight) of the produced usable powder (including reground sinter) was as follows:
  • a desirable powder of intermediate size was thus produced, the metal powder being appropriate for further processing.
  • EXAMPLE 5 Auxiliary nitrogen gas was also employed to agglomerate and cool particles of metal powder produced from an AKDQ steel (the steel having the characteristics of the first example) using apparatus such as shown in FIG. 8.
  • the atomizing chamber 16 was of the same dimensions and was initially prepared in the same manner as in the processing using the device of Example 1. 500 lbs. of molten steel were discharged from the tundish 12 at a temperature of about 3105 F. and at a rate of about 172 lbs. per minute through a -inch diameter feeding nozzle in the tundish. A three-inch inside diameter nozzle of the converging-diverging type (FIG.
  • Nitrogen gas of 99.995% purity was directed toward the stream at the rate of 1100 cu. ft. per minute at a pressure of lbs. per sq. in. to atomize the stream. Additionally, nitrogen gas of 99.995 purity was injected into the stream of particles by secondary nozzles such as 13 22b at the rate of 240 cu. ft. per minute at a pressure of lbs. per sq. in.
  • the product of the process was again classified into atomized fines, atomized powder, and atomized sinter.
  • the fines comprised 8.6% (by weight) of the product and were of the same content and size as the fines of Example 1.
  • the majority of the intermediate sized powder was of irregular shape and coarse in nature. A cubic centimeter sample of produced powder flowed for 23.3 seconds through a 0.2 inch diameter orifice. The powder wasfound to be suitable for optimum compacting into steel plate although it was not highly agglomerated.
  • the atomized sinter constituted 39.7% (by Weight) of the product.
  • the bulk could be readily ground into usable powder so that the total amount of powder was 91.4% (by weight). Only about 1% of the molten metal was eventually found to be unusable.
  • the present invention provides apparatus and process for atomizing molten metal into a metal powder possessing optimum properties for compaction into metal plate, sheet, or strip, for example.
  • the invention allows a metal powder to be produced in agglomerated form, which results in stronger particle-to-particle bonds in the compacted product, but without particles containing oxide cpatings and without a sintered mass being formed at the base of the atomizing chamber which could not be readily ground into particles of desired size and shape.
  • the inmprovement comprising:
  • a method according to claim 13 in which the to a zone downstream therefrom; molten metal is a stream of aluminum-killed, drawing the improvement comprising: quality steel.

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  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
US834368A 1969-06-18 1969-06-18 Process for producing metal powder Expired - Lifetime US3655837A (en)

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3814558A (en) * 1969-09-04 1974-06-04 Metal Innovations Inc Apparatus for producing low oxide metal powders
US3963811A (en) * 1973-06-04 1976-06-15 National Research Institute For Metals Process for producing a composite metal powder
US4008653A (en) * 1974-12-04 1977-02-22 Lear Siegler, Inc. Diffuser
US4104342A (en) * 1971-08-31 1978-08-01 Mannesmann Aktiengesellschaft Method for making metal powder of low oxygen content
US4359434A (en) * 1977-09-06 1982-11-16 Svenskt Stal Aktiebolag Process for granulating molten material
US4420441A (en) * 1982-02-23 1983-12-13 National Research Development Corp. Method of making a two-phase or multi-phase metallic material
US4787935A (en) * 1987-04-24 1988-11-29 United States Of America As Represented By The Secretary Of The Air Force Method for making centrifugally cooled powders
US4869469A (en) * 1987-04-24 1989-09-26 The United States Of America As Represented By The Secretary Of The Air Force System for making centrifugally cooling metal powders
AT395230B (de) * 1989-11-16 1992-10-27 Boehler Gmbh Verfahren zur herstellung von vormaterial fuer werkstuecke mit hohem anteil an metallverbindungen
US5589199A (en) * 1990-10-09 1996-12-31 Iowa State University Research Foundation, Inc. Apparatus for making environmentally stable reactive alloy powders
US20130236582A1 (en) * 2012-03-07 2013-09-12 Qualmat, Inc. Apparatus for producing refractory compound powders
CN103566817A (zh) * 2012-07-31 2014-02-12 株式会社理光 颗粒材料制造设备及颗粒材料制造方法
CN105921760A (zh) * 2016-06-29 2016-09-07 宁波科扬贵金属合金科技有限公司 银氧化锡的加工设备及其加工工艺
CN105945295A (zh) * 2016-06-29 2016-09-21 宁波科扬贵金属合金科技有限公司 一种银氧化锡的加工设备及其加工工艺
CN109482895A (zh) * 2019-01-22 2019-03-19 上海材料研究所 一种3d打印用低卫星球金属粉末的气雾化制备方法
EP3868492A1 (fr) * 2020-02-20 2021-08-25 Kolon Industries, Inc. Buse de pulvérisation et appareil de fabrication de poudre de métal la comprenant
US11389873B2 (en) * 2017-04-13 2022-07-19 Tenova S.P.A. Method for producing metal powders by means of gas atomization and production plant of metal powders according to such method

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JPS6224481B2 (fr) * 1974-12-18 1987-05-28 Intaanashonaru Nitsukeru Co Inc Za
US4801412A (en) * 1984-02-29 1989-01-31 General Electric Company Method for melt atomization with reduced flow gas
US4619597A (en) * 1984-02-29 1986-10-28 General Electric Company Apparatus for melt atomization with a concave melt nozzle for gas deflection
CH666639A5 (fr) * 1985-04-16 1988-08-15 Battelle Memorial Institute Procede de fabrication de poudres metalliques.
DE3811077A1 (de) * 1988-03-29 1989-10-19 Mannesmann Ag Einrichtung fuer die zerstaeubung eines giessstrahles fluessigen metalls
GB8813338D0 (en) * 1988-06-06 1988-07-13 Osprey Metals Ltd Powder production
DE4132693A1 (de) * 1991-10-01 1993-04-08 Messer Griesheim Gmbh Verfahren und vorrichtung zur herstellung von pulvern
GB9302387D0 (en) * 1993-02-06 1993-03-24 Osprey Metals Ltd Production of powder
CN105665719B (zh) * 2016-01-23 2018-02-02 山东理工大学 自由降落混粉气雾化水冷快凝磁性磨料制备设备
CN105665726B (zh) * 2016-01-23 2018-08-31 山东理工大学 自由降落双喷嘴混粉气雾化水冷快凝金属基金刚石磁性磨料制备方法
CN105665728B (zh) * 2016-01-23 2018-07-31 山东理工大学 自由降落双喷嘴混粉气雾化水冷快凝金属基碳化钛磁性磨料制备方法
CN105618769B (zh) * 2016-01-23 2018-10-09 山东理工大学 混粉气雾化水冷快凝磁性磨料制备的水冷快凝方法及水冷快凝装置
CN105665720B (zh) * 2016-01-23 2019-06-28 山东理工大学 自由降落式混粉气雾化磁性磨料制备双级雾化装置
CN105665724B (zh) * 2016-01-23 2018-07-31 山东理工大学 硬质磨料在磁性磨料金属基体中深浅分布的水冷快凝控制方法
CN105665722B (zh) * 2016-01-23 2018-08-31 山东理工大学 自由降落双喷嘴混粉气雾化水冷快凝金属基氧化铝磁性磨料制备方法
CN105665723B (zh) * 2016-01-23 2018-08-31 山东理工大学 自由降落双喷嘴混粉气雾化水冷快凝金属基碳化硅磁性磨料制备方法
CN105665727B (zh) * 2016-01-23 2019-01-11 山东理工大学 自由降落双级混粉气雾化水冷快凝磁性磨料制备方法
CN105665721B (zh) * 2016-01-23 2018-07-31 山东理工大学 自由降落双喷嘴混粉气雾化水冷快凝金属基氧化铬磁性磨料制备方法
CN105665725B (zh) * 2016-01-23 2018-08-31 山东理工大学 自由降落双喷嘴混粉气雾化水冷快凝金属基cbn磁性磨料制备方法
CN105618770B (zh) * 2016-01-23 2019-01-11 山东理工大学 混粉气雾化磁性磨料制备用螺旋自动精确送混粉器
JP2017218633A (ja) * 2016-06-08 2017-12-14 積水化学工業株式会社 複合粒子の製造方法

Cited By (23)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3814558A (en) * 1969-09-04 1974-06-04 Metal Innovations Inc Apparatus for producing low oxide metal powders
US4104342A (en) * 1971-08-31 1978-08-01 Mannesmann Aktiengesellschaft Method for making metal powder of low oxygen content
US3963811A (en) * 1973-06-04 1976-06-15 National Research Institute For Metals Process for producing a composite metal powder
US4008653A (en) * 1974-12-04 1977-02-22 Lear Siegler, Inc. Diffuser
US4359434A (en) * 1977-09-06 1982-11-16 Svenskt Stal Aktiebolag Process for granulating molten material
US4420441A (en) * 1982-02-23 1983-12-13 National Research Development Corp. Method of making a two-phase or multi-phase metallic material
US4787935A (en) * 1987-04-24 1988-11-29 United States Of America As Represented By The Secretary Of The Air Force Method for making centrifugally cooled powders
US4869469A (en) * 1987-04-24 1989-09-26 The United States Of America As Represented By The Secretary Of The Air Force System for making centrifugally cooling metal powders
AT395230B (de) * 1989-11-16 1992-10-27 Boehler Gmbh Verfahren zur herstellung von vormaterial fuer werkstuecke mit hohem anteil an metallverbindungen
US5589199A (en) * 1990-10-09 1996-12-31 Iowa State University Research Foundation, Inc. Apparatus for making environmentally stable reactive alloy powders
US20130236582A1 (en) * 2012-03-07 2013-09-12 Qualmat, Inc. Apparatus for producing refractory compound powders
US9926197B2 (en) 2012-03-07 2018-03-27 Bo Liu Method and apparatus for producing compound powders
CN103566817A (zh) * 2012-07-31 2014-02-12 株式会社理光 颗粒材料制造设备及颗粒材料制造方法
KR101552390B1 (ko) * 2012-07-31 2015-09-10 가부시키가이샤 리코 미립자 제조 장치, 미립자 제조 방법, 및 이에 의해 제조되는 토너
US9141010B2 (en) * 2012-07-31 2015-09-22 Ricoh Company, Ltd. Particulate material production apparatus, and particulate material production method
CN103566817B (zh) * 2012-07-31 2016-01-13 株式会社理光 颗粒材料制造设备及颗粒材料制造方法
CN105921760A (zh) * 2016-06-29 2016-09-07 宁波科扬贵金属合金科技有限公司 银氧化锡的加工设备及其加工工艺
CN105945295A (zh) * 2016-06-29 2016-09-21 宁波科扬贵金属合金科技有限公司 一种银氧化锡的加工设备及其加工工艺
CN105945295B (zh) * 2016-06-29 2018-07-24 宁波科扬贵金属合金科技有限公司 一种银氧化锡的加工设备及其加工工艺
CN105921760B (zh) * 2016-06-29 2018-08-14 宁波科扬贵金属合金科技有限公司 银氧化锡的加工设备及其加工工艺
US11389873B2 (en) * 2017-04-13 2022-07-19 Tenova S.P.A. Method for producing metal powders by means of gas atomization and production plant of metal powders according to such method
CN109482895A (zh) * 2019-01-22 2019-03-19 上海材料研究所 一种3d打印用低卫星球金属粉末的气雾化制备方法
EP3868492A1 (fr) * 2020-02-20 2021-08-25 Kolon Industries, Inc. Buse de pulvérisation et appareil de fabrication de poudre de métal la comprenant

Also Published As

Publication number Publication date
NL7008924A (fr) 1970-12-22
FR2046873A1 (fr) 1971-03-12
GB1298031A (en) 1972-11-29
BE752159A (fr) 1970-12-18
FR2046873B1 (fr) 1973-01-12
JPS496755B1 (fr) 1974-02-15

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Effective date: 19850612