EP3766609A1 - Procédé et dispositif de purge d'un espace de production de poudre métallique - Google Patents

Procédé et dispositif de purge d'un espace de production de poudre métallique Download PDF

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Publication number
EP3766609A1
EP3766609A1 EP19020434.7A EP19020434A EP3766609A1 EP 3766609 A1 EP3766609 A1 EP 3766609A1 EP 19020434 A EP19020434 A EP 19020434A EP 3766609 A1 EP3766609 A1 EP 3766609A1
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EP
European Patent Office
Prior art keywords
liquid
chamber
cryogen
melt
metal powder
Prior art date
Legal status (The legal status 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 status listed.)
Withdrawn
Application number
EP19020434.7A
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German (de)
English (en)
Inventor
Ian Hibbitt
Glen Graydon
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Linde GmbH
Original Assignee
Linde GmbH
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 Linde GmbH filed Critical Linde GmbH
Priority to EP19020434.7A priority Critical patent/EP3766609A1/fr
Publication of EP3766609A1 publication Critical patent/EP3766609A1/fr
Withdrawn legal-status Critical Current

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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
    • 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
    • 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
    • B22F2202/00—Treatment under specific physical conditions
    • B22F2202/03—Treatment under cryogenic or supercritical conditions
    • 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
    • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy

Definitions

  • the present invention relates to a method and to a device for purging a production space for metal powder production.
  • metal powder There are numerous processes for producing metal powder. These include the mechanical comminution of solid metal, the precipitation from salt solutions, the thermal decomposition of a chemical compound, the reduction of a chemical compound, usually the oxide in the solid phase, the electrolytic deposition and the atomization of liquid metal. The latter three methods are most commonly used in practice for the production of metal powder.
  • molten metal is broken up into small droplets and rapidly solidified before the molten droplets come into contact with each other or with a solid surface.
  • the principle of this process is based on the division of a thin liquid metal jet through a high velocity gas or liquid stream. Air, nitrogen and argon are the most commonly used gases, as a liquid, especially water is used.
  • melt distribution i.e. centrifugal atomization, in which molten droplets are spun off a rotating source.
  • a melt of the metal to be atomized or the alloy to be atomized is built up and overheated accordingly.
  • This superheated melt usually runs over a second smaller crucible or a pouring funnel and forms there a melt jet, which falls vertically through a nozzle construction.
  • the melt jet is atomized by a gas (carrier gas) and the resulting droplets solidify in a spray chamber.
  • the metal powder is separated from the carrier gas.
  • High-purity powders made of special steel, super alloys and other high-alloy or oxidation-sensitive materials can be advantageously produced by atomizing with inert gas. This process usually yields spherical powders which are more suitable for conventional mechanical molding of molded parts, for isostatic pressing and powder injection molding processing.
  • the ASEA-STORA process is frequently used for atomizing high-speed steel melts.
  • purified inert gas such as N 2 and Ar
  • powders can be produced with approximately 100 ppm oxygen.
  • the atomization chamber is cooled from the outside and a water-cooled bottom is used to collect the powders.
  • Another method involves atomization with gases in a NANOVAL Laval nozzle.
  • reactive metals such as titanium or zirconium
  • methods are advantageous which do not allow contact of the molten metal with ceramic crucible material, since this could lead to oxidation of the melt and possibly destruction of the crucible. Therefore, the reactive metal is melted inductively or by means of plasma in a cooled copper crucible. Between the copper crucible and the melt, a thin solidified layer of the metal to be atomized forms, which effectively prevents a reaction of the melt with the crucible material.
  • the metal to be atomized or the alloy to be atomized is fed as an electrode in rod form perpendicular to an annular induction coil and melted superficially here.
  • the rod undergoes a rotary movement during the process.
  • the melt thus produced finally drips in free fall through an annular nozzle, is atomized and solidified here. Subsequently, the powder is deposited in a atomization holder.
  • plasma atomization is used. An approximately 3 mm diameter wire made from the alloy to be atomized is fed to an array of three plasma torches, where it is melted and atomized in one step. The purity of the starting material, the absence of any crucible material and the melting under inert atmosphere gives a final product of the highest purity.
  • melts under vacuum which must be assigned to atomization in principle, is possible with the help of noble gases or hydrogen.
  • the gas-enriched melt under pressure is forced in a thin stream into an evacuated chamber.
  • the expansion of the dissolved gas in the melt divides these into fine droplets.
  • a method for purging a production space for metal powder production wherein a liquid inert cryogen is fed to the production space in order to reduce oxygen and/or moisture levels in the production space.
  • a production space is a space or a chamber in which metal powder is generated, for example a spray chamber of a device for producing metal powder.
  • the inventors of the present invention have recognized that the current purging methods for the production of metal powders are insufficient in that oxygen and moisture (H 2 O) remain in the spray chamber.
  • a cryogenic fog can be produced when the liquid inert cryogen is entering the production space, in which the metal powder is atomized.
  • the cryogenic fog is preferably produced by a high-pressure liquid spray system directly into a spray chamber at the start of a purge cycle, wherein the high-pressure liquid spray system provides a pressure wave of inert gas through the chamber initially displacing the unwanted gases within the spray chamber into an exhaust system.
  • cryogenic fog produced by the high-pressure liquid spray system directly into the spray chamber at the start of the purge cycle provides the pressure wave of inert gas through the spray chamber. Thereby most of the unwanted gases within the spray chamber are displaced into an exhaust system of sufficient size and back pressure to prevent the over pressurization of the chamber.
  • the exhaust system has a none return device, for example a non-return valve, to prevent the back flow of oxygen or H 2 O into the chamber.
  • the cryogenic fog can rapidly condense any water vaper followed by droplets freezing within the chamber, wherein this increase in mass of the frozen droplet will cause frozen particles to be swept out on the purge cycle produced by the vaporizing cryogen.
  • the high-pressure liquid spray system can create a pulsating flow of cryogenic gas via an injector creating a series of pressure waves within the chamber.
  • the fog within the chamber can coalesces fine particles within the chamber, wherein these fine particles are removed prior to the start of a production process.
  • the ability to remove moisture very quickly from a spray chamber will reduce cycle times for the operator and will improve product quality by reducing residual humidity and a reduced purge and/or cycle time.
  • the use of the fog technology within the chamber will act to coalesce any very fine particles within the chamber which have to be removed prior to the start of the process.
  • t is proposed to inject inert gas into the vessel as a cryogenic liquid. This is further improved by creating a pulsating flow of cryogenic gas via an injector creating a series of pressure wave within the vessel.
  • an injection nozzle is provided that has a variable frequency of cryogenic inert gas injection.
  • Initial injection frequency will be of a long duration to rapidly reduce the oxygen concentration by a sweep purge.
  • the frequency of the cryogenic injection will be of a shorter duration producing the desired pressure wave to spread within the vessel.
  • the pressure waves of inert gas will promote a pressure purge principle to promote the removal of oxygen within any "dead" volumes within the vessel.
  • the pressure swing of the pulse will promote the displacement of "bound" oxygen on the material surface within the purge space (production space; spray chamber).
  • the method of operation will speed up the removal of the residual oxygen (or other gases required to be removed). Gases resulting from the metal melting process may be present from the previous operation cycles such as NO, NO 2 and CO 2 .
  • the liquid inert cryogen can be liquid Nitrogen, liquid Argon or liquid Helium or corresponding mixtures thereof.
  • the Method for producing metal powder comprises the further following steps: providing a melt, forming a melt jet or liquid sheet, atomizing the melt jet or liquid sheet by means of an atomizing fluid, forming metal powder particles from the melt jet.
  • An atomizing fluid can be an inert gas such as Argon, Helium, Neon, Krypton, Xenon or Radon or an active gas such as O 2 , CO 2 , H 2 , and N 2 , or mixtures thereof. Above all, water can be provided as the liquid atomizing fluid.
  • a device for metal powder manufacturing comprises for producing a metal powder, comprising a device for providing a melt, a nozzle device for atomizing the melt by means of an atomizing fluid, a spray chamber for forming metal powder particles from the atomizing melt by means of an atomizing fluid, characterized in that the device for feeding liquid inert cryogen comprises storage container/vessel for a liquid inert cryogen and a feeding device for feeding the liquid inert cryogen to the spray chamber.
  • the device for feeding liquid inert cryogen can comprise a high-pressure liquid spray system.
  • An oxygen sensor for measuring the proportion of oxygen (O2) in the spray chamber can be provided in the production space, wherein the oxygen sensor is connected to a control unit and the control unit is connected to the device for feeding liquid and creating the pressure pulse frequencies of inert cryogen for controlling the device for feeding liquid inert cryogen according to the value measured by the oxygen sensor.
  • the depletion of O2 measured by the sensor can be used to change the frequency of the pulses of inert cryogen.
  • a high concentration of O 2 corresponds to long pulse and a low concentration results in a fast pulse to promote pressure purging at low O 2 concentrations.
  • This device 1 comprises a melting crucible 2 for providing a molten metal.
  • the device 1 comprises a pouring funnel 3, which can be filled with melt by means of the melted crucible 2.
  • the pouring funnel 3 is provided with a ceramic coating.
  • An outlet channel of the pouring funnel 3 opens into a nozzle device 4.
  • the nozzle device 4 comprises centrally a passage opening 5, through which a melt jet formed by the outlet channel of the pouring funnel 3 can pass.
  • the passage opening 5 is surrounded by an annular atomizing fluid chamber 6 for receiving and distributing an atomizing fluid.
  • the atomizing fluid chamber 6 opens into an annular gap 7 arranged concentrically with the passage opening 5.
  • the annular gap 7 forms an atomizing nozzle for generating melt droplets from the melt jet.
  • a device for feeding atomizing fluid 8 is provided, by means of which the atomizing fluid can be provided to the atomizing fluid chamber 6.
  • the atomizing fluid supply device 8 has a storage tank 9 for the atomizing fluid, wherein the storage tank 9 is connected via a conduit 10 with the atomizing fluid chamber 6.
  • the device for feeding a liquid inert cryogen includes a storage container 12 for a liquid inert cryogen.
  • the storage container 12 is connected to the spray chamber 14 via a conduit 13.
  • liquid Argon or liquid Helium or liquid Nitrogen is stored.
  • An oxygen sensor for measuring the proportion of oxygen (O2) in the spray chamber can be provided in the production space, wherein the oxygen sensor is connected to a control unit and the control unit is connected to the device for controlling the frequency of feed liquid inert cryogen for controlling the device for feeding liquid inert cryogen according to the value measured by the oxygen sensor.
  • the oxygen sensor sets the frequency of the pulses of cryogen into the purge space. Shorter pulses are provided as the O 2 level lowers.
  • a purge cycle is started in the spray chamber by feeding a liquid cryogen to the spray chamber via a high-pressure liquid spray system. Thereby a cryogenic fog is produced.
  • the liquid inert cryogen can be liquid Nitrogen, liquid Argon or liquid Helium or other suitable liquid gas.
  • the high-pressure liquid spray system provides a pressure wave of inert gas through the chamber initially displacing the unwanted gases within the spray chamber into an exhaust system.
  • the cryogenic fog rapidly condenses any water vapor followed by the droplets freezing within the chamber.
  • the increase in mass of the frozen droplet will cause frozen particles to be swept out on the purge cycle produced by the vaporizing cryogen.
  • the high-pressure liquid spray system preferably creates a pulsating flow of cryogenic gas via an injector creating a series of pressure waves within the chamber.
  • the fog within the chamber can coalesces fine particles within the chamber, wherein these fine particles are removed prior to the start of a production process.
  • the fog within the chamber will act to coalesce any very fine particles within the chamber which have to be removed prior to the start of the process.
  • the proportion of oxygen (O2) in the spray chamber can preferably be measured via an oxygen sensor (for example: Linde ADDvanceTM 0 2 precision) which is disposed in the production space, wherein the oxygen sensor is connected to a control unit and the control unit is connected to the device for controlling the frequency of feed liquid inert cryogen for controlling the device for feeding liquid inert cryogen according to the value measured by the oxygen sensor. That means the oxygen sensor is connected to the control unit and the control unit is connected to the device for feeding liquid and creating the pressure pulse frequencies of inert cryogen for controlling the device for feeding liquid inert cryogen according to the value measured by the oxygen sensor.
  • an oxygen sensor for example: Linde ADDvanceTM 0 2 precision
  • the depletion of O2 measured by the sensor can be used to change the frequency of the pulses of inert cryogen.
  • a high concentration of O 2 corresponds to long pulse and a low concentration results in a fast pulse to promote pressure purging at low O 2 concentrations.
  • the oxygen sensor preferably sets the frequency of the pulses of cryogen into the purge space. Shorter pulses are provided as the O 2 level lowers. Longer pulses are provided as the O 2 level rises.
  • melt of a metal to be atomized or an alloy to be atomized is first built up and superheated in the melting crucible 2.
  • the superheated melt is introduced into the pouring funnel 3 and forms in its outlet channel a melt jet, which passes vertically through the through hole 5 of the nozzle device 4.
  • This melt jet is atomized via the atomizing nozzle 7 of the nozzle device 4 in the atomizing/spray chamber 14 by means of the atomizing fluid.
  • a atomizing fluid can be an inert gas such as Argon, Helium, Neon, Krypton, Xenon or Radon or an active gas such as O 2 , CO 2 , H 2 , and N 2 , or mixtures thereof. Above all, water can be provided as the liquid atomizing fluid.
  • the resulting droplets solidify in the atomization chamber 14 in motion or I the movement respectively.

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  • Manufacture Of Metal Powder And Suspensions Thereof (AREA)
EP19020434.7A 2019-07-18 2019-07-18 Procédé et dispositif de purge d'un espace de production de poudre métallique Withdrawn EP3766609A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP19020434.7A EP3766609A1 (fr) 2019-07-18 2019-07-18 Procédé et dispositif de purge d'un espace de production de poudre métallique

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
EP19020434.7A EP3766609A1 (fr) 2019-07-18 2019-07-18 Procédé et dispositif de purge d'un espace de production de poudre métallique

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Publication Number Publication Date
EP3766609A1 true EP3766609A1 (fr) 2021-01-20

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116984618A (zh) * 2023-09-28 2023-11-03 季华实验室 一种气雾化设备

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60215702A (ja) * 1984-04-06 1985-10-29 Iwatani & Co 金属微粉末製造方法
US4897111A (en) * 1987-09-09 1990-01-30 Leybold Aktiengesellschaft Method for the manufacture of powders from molten materials
EP0544068A2 (fr) * 1991-10-01 1993-06-02 Messer Griesheim Gmbh Procédé et dispositif pour la fabrication de poudres
US20020125591A1 (en) * 2000-12-04 2002-09-12 Jaynes Scot Eric Process and apparatus for producing atomized powder using recirculating atomizing gas
US20170305808A1 (en) * 2012-04-12 2017-10-26 Iowa State University Research Foundation, Inc. Stability of gas atomized reactive powders through multiple step in-situ passivation

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS60215702A (ja) * 1984-04-06 1985-10-29 Iwatani & Co 金属微粉末製造方法
US4897111A (en) * 1987-09-09 1990-01-30 Leybold Aktiengesellschaft Method for the manufacture of powders from molten materials
EP0544068A2 (fr) * 1991-10-01 1993-06-02 Messer Griesheim Gmbh Procédé et dispositif pour la fabrication de poudres
US20020125591A1 (en) * 2000-12-04 2002-09-12 Jaynes Scot Eric Process and apparatus for producing atomized powder using recirculating atomizing gas
US20170305808A1 (en) * 2012-04-12 2017-10-26 Iowa State University Research Foundation, Inc. Stability of gas atomized reactive powders through multiple step in-situ passivation

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116984618A (zh) * 2023-09-28 2023-11-03 季华实验室 一种气雾化设备
CN116984618B (zh) * 2023-09-28 2023-12-15 季华实验室 一种气雾化设备

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