WO1989000471A1 - Desintegration centrifuge - Google Patents

Desintegration centrifuge Download PDF

Info

Publication number
WO1989000471A1
WO1989000471A1 PCT/US1988/002478 US8802478W WO8900471A1 WO 1989000471 A1 WO1989000471 A1 WO 1989000471A1 US 8802478 W US8802478 W US 8802478W WO 8900471 A1 WO8900471 A1 WO 8900471A1
Authority
WO
WIPO (PCT)
Prior art keywords
cup
rotating
ligaments
speed
substrate
Prior art date
Application number
PCT/US1988/002478
Other languages
English (en)
Inventor
Robert E. Maringer
Aspi N. Patel
Original Assignee
Battelle Development Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Battelle Development Corporation filed Critical Battelle Development Corporation
Publication of WO1989000471A1 publication Critical patent/WO1989000471A1/fr

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Classifications

    • 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
    • B22F9/10—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 using centrifugal force

Definitions

  • the invention relates to a method for formin particles and fibers or a spray casting of such particle and fibers from normally solid materials, such as metals
  • the method relates to existing centrifugal atomizatio technology in that a rotating substrate element i used to break up a stream of liquid.
  • Current technique for making metal powder include supplyin metal to a rotating hollow element which has hole in its walls. The liquid metal is broken up and ejecte by centrifugal force through the holes. The ejecte metal then cools in the air and solidifies to a meta particulate having a diameter which depends on th hole size.
  • the plugging of small holes prevent fine particles from being produced, and there ar generally temperature limitations on such elements.
  • Another liquid atomization technique involve the disintegration of a stream of liquid metal by blast of pressurized air, water, oil, or other fluid. This may result in the reaction with or trapping o the atomizing fluid with the particulate.
  • the invention 0 is a method of producing fine fiber, fine powder, fine flake or spray castings built up from such fibers, flake and/or powders from a normally-solid material having a viscosity in the range of about 0.001-1 poise at temperatures within 25° of its equilibrium melting 5 point in °K.
  • the method comprises rotating and heating a cup-like element having an upwardly inclined wall portion, introducing the normally-solid material in molten form into the cup forming ligaments and droplets of the material, and solidifying the ligaments or 0 droplets.
  • the ligaments or droplets can be cooled during flight, in which case fibers or particles are formed. Or the ligaments or droplets can be propelled against a substrate surface and cooled in which case individual 5 flakes can be formed or a sheet casting can be incrementally built up on the substrate.
  • Metals, intermetallics or ceramics are examples of materials which can be disintegrated according to the invention.
  • a protective atmosphere or vacuum may 0 surround the process.
  • the cup may have contoured (undulating, curved) walls but preferably has at least a small central bottom area and straight, angled walls.
  • the walls more preferably make an angle of between about 5° and 65°
  • Figures 1-3 are sectional, side elevation views of cups which can be used to disintegrate molten materials according to the inventive method.
  • Figure 4 shows a force diagram for a liquid element on the wall of a rotating cup (according to the invention). '
  • Figure 5 is a sectional, side-elevation view of spray casting apparatus which can be used to practice the invention.
  • Figures 6(a) and 6(b) are sectional, side elevation and plan views of a rotating cup according to the invention and a rotating cylindrical surface for capturing metal fibers from the cup.
  • flat plate centrifugal atomization has used cooled metal or refractory ceramic disks. It has required high speeds and accurate positioning of the liquid delivery orifice and the disk to achieve fine, uniform distribution powders. If the liquid is not introduced at the center, it reaches the periphery at different rates and causes a wider distribution of velocities and particle sizes.
  • a cup reduces this tendency for off-center introduction and also allows the liquid to be retained longer on the walls, allowing it to more nearly reach the velocity of the cup itself before expulsion. This feature, along with heating the cup, results in finer, more narrow particle size or fiber diameter distribution.
  • a cup 11 for practicing the invention comprises a hollowed, cylindrical body having a flat bottom portion 12 and upwardly inclined wall 13.
  • a shaft 14 is attached at the underside to rotate the cup.
  • the cup may be externally heated as with induction coils 17, for example and be made of ceramic material or metal with an insulating liner.
  • Figures 2 and 3 show variants of the cup.
  • Figure 2 shows a cup 21 having a rounded wall 22.
  • Figure 3 shows a cup 31 with an undulating wall 32.
  • each cup (such as shown in Figures 1-3) is generally symmetric about an axis of rotation and has a cavity with upwardly inclined walls.
  • the walls may be straight or contoured.
  • the cavity preferably has a bottom portion against which the molten material 16 is directed during operation as from a conduit 15. From the bottom, the molten material spreads up the inclined walls and is thrown from the rotating cup in very fine ligaments which may also be broken to droplets at high speed.
  • the liquid On a rotating flat disk, the liquid is subject to the centrifugal force accelerating it rapidly to the edge of the disk. It is also subject to shearing forces of the rotating disk. To obtain the necessary shear for production of very fine ligaments (e.g. 10-20 ⁇ diameter), the disk speed needs to be very high. To the contrary, using a rotating cup with an upwardly inclined wall, the speed can be substantially less than the disk to produce the very fine ligaments. We believe that this is because of the higher residence time of the liquid on the cup wall which allows the tangential velocity component of the liquid to more nearly reach the velocity of the cup before it is expelled. This adds additional energy for breakup of the liquid film at the cup edge.
  • very fine ligaments e.g. 10-20 ⁇ diameter
  • a cup with upwardly inclined wall portion we mean, therefore, a cup having a wall wherein the liquid film is exposed to not only a shearing force and a radial component of centrifugal force but also a normal component of centrifugal force.
  • This is graphically shown in Figure 4 where a liquid element on the rotating wall is exposed to both radial (F j *.) and normal (F-s--) centrifugal forces.
  • ( ⁇ ) made by the inclined wall portion with the vertical axis of rotation be in the range of between about 5° and 65°.
  • the cup is preferably oriented such that the cup axis of rotation is substantially vertical.
  • the cup shape also is advantageous over a flat disk in allowing more variability in introducing the liquid. No particular spacing is necessary between the bottom of the cup and the point of entry of the liquid, though splashing should obviously be avoided.
  • an off-center pour on a flat disk can cause a wide distribution of particle sizes in the product. This condition is much less prevalent in the cup design because all the liquid approaches the same high tangential velocity and disintegration forces prior to breakup.
  • cup speed, cup temperature and liquid viscosity affect product size.
  • the cup is generally rotated such that the speed at the perimeter is 2-200 m/sec, though conditions and desired product requirements might dictate speeds outside this range.
  • the cup is typically heated such that its temperature is at or above the liquidus temperature of the liquid material. Again, some particular requirements might dictate higher or lower temperature.
  • Materials which can be disintegrated according to the invention are those normally solid materials which have a viscosity in the range of about 0.001 to 1 poise at temperatures within 25° of its equilibrium melting point (.in °K). This is intended to i-nclude primarily crystalline and glassy metals, but also intermetallics and ceramic materials.
  • Ligaments and droplets that are projected from the rotating cup may be further treated to produce powder, flake, fibers or a spray casting.
  • the ligaments are disintegrated to fine droplets by the high speed rotation and are allowed to cool and solidify in the surrounding atmosphere before collection. At lower speeds or at higher viscosities, the ligaments will not be broken as easily and fibers can be preferentially produced in the same manner of cooling.
  • Flakes can be produced by impacting the droplets from the cup onto an adjacent solid surface prior to complete solidification. Rotation positioning and/or surface treatment of the solid surface can be used to assure individual flakes are produced and collected rather than accreted.
  • Fibers may also be produced according to the invention from the ligaments leaving the cup by capturing them in a liquid quenchant moving in substantially the same direction and at slightly higher or lower speed than the perimeter of the cup. As shown in Figures 6(a) and 6(b), this may be accomplished by rotating the cup 61 within a rotating cylindrical surface 62 upon which a layer of liquid quenchant 63 is held by centrifugal force. If the speed of the cylindrical surface and quenchant is on the order of about 0.7-1.3 times the speed of the melt ligaments, they will be stretched, captured and solidified in the quenchant without significant additional disintegration.
  • FIGS 6(a) and 6(b) show the melt 64 and its disintegration at the cup periphery into ligaments
  • the method can also be used to produce spray castings by incremental consolidation of particles and flakes on a substrate placed in their path. Unlike prior methods of spray casting, this method may be carried out in vacuum.
  • the spray casting method is depicted in Figure 5.
  • a cup 41 is rotated by shaft 42 within a cylindrical shell 46.
  • the cup is also heated by any convenient heating means (not shown).
  • the shell is angled with respect to the cups's rotational axis.
  • Normally solid material is introduced in liquid form through conduit 44 and spreads to a thin layer 43 up the cup wall and is thrown in ligaments and/or droplets against the shell wall forming a thin deposit 47.
  • the shell 46 is rotated and/or displaced parallel to its longitudinal axis to spread the deposit and make it more uniform. When the deposit cools, it is removed from the shell (it may shrink away from the shell) and is further processed as by rolling, for example.
  • the first set of experiments were conducted to characterize and determine the mechanism of liquid breakup with a cup. The effects of rotational cup speed and liquid viscosity on stream disintegration were studied by stroboscopy and high speed photography. Water and a mixture of glycerine and water (1:1) were used as the liquid.
  • the number and diameter of the ligaments formed are directly proportional to the cup speed. These results indicate that the number of ligaments formed increases and their diameter decreases as cup speed increases.
  • the cup speed also has considerable influence over the length of the ligaments. As the cup speed increases, the ligament length before disintegration into finer spray droplets decreases. This is to be expected since higher cup speeds result in a combination of finer, and hence weaker ligaments and higher wind shear. The tendency to form larger, more stable ligaments is much higher for the more viscous mixture of alloys as compared to pure metal.
  • the particle size distribution of powders produced are shown in Table 1. It should be noted that the values of cup speed shown in Table 1 are an average of the cup speed at the initiation and end of melt pour. This was necessary since a very low torque motor was used to drive the cup and there was a gradual decrease in cup speed from the onset to the end of the run.
  • the sieve analysis in Table 1 indicates that, in general, the particle size decreases with increasing cup speed up to about 1900 rpm.
  • Finer particles were generally produced in the cup with 45° walls. This may be due to a lower dwell time on the wall and, therefore, a higher superheat during fractionation at the lip.
  • a 102 mm cup such as shown in Figure 1 was machined and tested at four different wall angles. Molten aluminum was introduced to the heated cup rotating at 2000 rpm. Particles were air cooled and collected. The average particle size as a function of the wall angle ( ⁇ ) was as follows:
  • Example 5 Production of Fibers
  • a 10 cm cup such as shown in Figure 1 with a wall angle of 65° was rotated at about 4000 rpm.
  • a larger cylindrical vessel having a water quenchant held therein was rotated in the same direction around the smaller cup at about 4400 rpm.
  • the water formed a water wall such as shown in Figure 6.
  • a stream of 915 alloy (in atomic percent, 63 Ni-12Cr-4Fe-13B-8Si) at 150°C of superheat (above the melting temperature) was directed into the smaller cup at three different cup temperatures. Ligaments were formed at the smaller cup periphery and these were thrown to the water wall where they were stretched into longer fibers as reported below: Table 3
  • the cup temperature is seen to have a significant effect on the condition of the ligaments to be further stretched by the water wall.

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  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)

Abstract

On produit des fibres ou des poudres et des coulées en grappe desdites fibres ou poudres, à partir des matières en fusion par une technique de vaporisation centrifuge à partir d'une cuvette (1) tournante. La cuvette comporte une paroi (2) inclinée améliorant les conditions de fonctionnement par rapport à la vaporisation centrifuge à plaque plate.
PCT/US1988/002478 1987-07-20 1988-07-20 Desintegration centrifuge WO1989000471A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US7517387A 1987-07-20 1987-07-20
US075,173 1987-07-20

Publications (1)

Publication Number Publication Date
WO1989000471A1 true WO1989000471A1 (fr) 1989-01-26

Family

ID=22124034

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1988/002478 WO1989000471A1 (fr) 1987-07-20 1988-07-20 Desintegration centrifuge

Country Status (1)

Country Link
WO (1) WO1989000471A1 (fr)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996008302A2 (fr) * 1994-09-15 1996-03-21 Pall Corporation Milieu filtrant et son utilisation dans un filtre pour coussin gonflable de securite
US8101006B2 (en) 2008-04-22 2012-01-24 The Gillette Company Centrifugal atomization for producing zinc powder
CN103212717A (zh) * 2013-02-26 2013-07-24 连云港倍特超微粉有限公司 一种制备锌合金喷丸的转筒式装置及其方法
GB2500039A (en) * 2012-03-08 2013-09-11 Siemens Plc Rotary slag granulator with an annular metal disc and central cylinder containing plug of refractory material
CN103769595A (zh) * 2013-11-26 2014-05-07 王利民 一种制备微晶和非晶态粉末材料的方法
CN103781575A (zh) * 2011-08-26 2014-05-07 西门子有限公司 渣粒化设备
EP2747920A1 (fr) * 2011-08-26 2014-07-02 Siemens Plc Dispositif de granulation de scorie
WO2020102200A1 (fr) 2018-11-14 2020-05-22 Sun Chemical Corporation Pigments de bismuth métalliques
CN113458403A (zh) * 2021-07-23 2021-10-01 成都先进金属材料产业技术研究院股份有限公司 旋转圆杯制备高品质3d打印用球形金属粉末的装置和方法
CN113523294A (zh) * 2021-07-23 2021-10-22 成都先进金属材料产业技术研究院股份有限公司 旋转圆杯制备3d打印用超细球形金属粉末的装置和方法
CN113547127A (zh) * 2021-07-20 2021-10-26 成都先进金属材料产业技术研究院股份有限公司 低成本制备3d打印用球形金属粉末的装置和方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2439772A (en) * 1946-04-09 1948-04-13 Steel Shot Producers Inc Method and apparatus for forming solidified particles from molten material
US4069045A (en) * 1974-11-26 1978-01-17 Skf Nova Ab Metal powder suited for powder metallurgical purposes, and a process for manufacturing the metal powder
US4218410A (en) * 1975-06-28 1980-08-19 Leybold-Heraeus Gmbh & Co. Kg Method for the production of high-purity metal powder by means of electron beam heating
US4512384A (en) * 1983-09-14 1985-04-23 Tadeusz Sendzimir Continuous spray casting

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2439772A (en) * 1946-04-09 1948-04-13 Steel Shot Producers Inc Method and apparatus for forming solidified particles from molten material
US4069045A (en) * 1974-11-26 1978-01-17 Skf Nova Ab Metal powder suited for powder metallurgical purposes, and a process for manufacturing the metal powder
US4218410A (en) * 1975-06-28 1980-08-19 Leybold-Heraeus Gmbh & Co. Kg Method for the production of high-purity metal powder by means of electron beam heating
US4512384A (en) * 1983-09-14 1985-04-23 Tadeusz Sendzimir Continuous spray casting

Cited By (14)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1996008302A2 (fr) * 1994-09-15 1996-03-21 Pall Corporation Milieu filtrant et son utilisation dans un filtre pour coussin gonflable de securite
WO1996008302A3 (fr) * 1994-09-15 1996-07-04 Pall Corp Milieu filtrant et son utilisation dans un filtre pour coussin gonflable de securite
US8101006B2 (en) 2008-04-22 2012-01-24 The Gillette Company Centrifugal atomization for producing zinc powder
EP2747920B1 (fr) * 2011-08-26 2017-03-15 Primetals Technologies, Limited Dispositif de granulation de scorie
CN103781575A (zh) * 2011-08-26 2014-05-07 西门子有限公司 渣粒化设备
EP2747920A1 (fr) * 2011-08-26 2014-07-02 Siemens Plc Dispositif de granulation de scorie
CN103781575B (zh) * 2011-08-26 2016-12-21 西门子有限公司 渣粒化设备
GB2500039A (en) * 2012-03-08 2013-09-11 Siemens Plc Rotary slag granulator with an annular metal disc and central cylinder containing plug of refractory material
CN103212717A (zh) * 2013-02-26 2013-07-24 连云港倍特超微粉有限公司 一种制备锌合金喷丸的转筒式装置及其方法
CN103769595A (zh) * 2013-11-26 2014-05-07 王利民 一种制备微晶和非晶态粉末材料的方法
WO2020102200A1 (fr) 2018-11-14 2020-05-22 Sun Chemical Corporation Pigments de bismuth métalliques
CN113547127A (zh) * 2021-07-20 2021-10-26 成都先进金属材料产业技术研究院股份有限公司 低成本制备3d打印用球形金属粉末的装置和方法
CN113458403A (zh) * 2021-07-23 2021-10-01 成都先进金属材料产业技术研究院股份有限公司 旋转圆杯制备高品质3d打印用球形金属粉末的装置和方法
CN113523294A (zh) * 2021-07-23 2021-10-22 成都先进金属材料产业技术研究院股份有限公司 旋转圆杯制备3d打印用超细球形金属粉末的装置和方法

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