EP0505067B1 - Verfahren zum Formen eines Formkörpers aus feinen Teilchen mit einer Trägerflüssigkeit unter einem Druckfeld - Google Patents

Verfahren zum Formen eines Formkörpers aus feinen Teilchen mit einer Trägerflüssigkeit unter einem Druckfeld Download PDF

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Publication number
EP0505067B1
EP0505067B1 EP19920301994 EP92301994A EP0505067B1 EP 0505067 B1 EP0505067 B1 EP 0505067B1 EP 19920301994 EP19920301994 EP 19920301994 EP 92301994 A EP92301994 A EP 92301994A EP 0505067 B1 EP0505067 B1 EP 0505067B1
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EP
European Patent Office
Prior art keywords
fine particles
mold chamber
carrier fluid
mixture
mold
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.)
Expired - Lifetime
Application number
EP19920301994
Other languages
English (en)
French (fr)
Other versions
EP0505067A1 (de
Inventor
Kazuyuki Toki
Mikio Murachi
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.)
Toyota Motor Corp
Original Assignee
Toyota Motor Corp
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
Priority claimed from JP8361391A external-priority patent/JPH04294102A/ja
Priority claimed from JP3169232A external-priority patent/JPH04368808A/ja
Priority claimed from JP16923491A external-priority patent/JPH04368806A/ja
Priority claimed from JP16923391A external-priority patent/JPH04368809A/ja
Application filed by Toyota Motor Corp filed Critical Toyota Motor Corp
Publication of EP0505067A1 publication Critical patent/EP0505067A1/de
Application granted granted Critical
Publication of EP0505067B1 publication Critical patent/EP0505067B1/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B28—WORKING CEMENT, CLAY, OR STONE
    • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
    • B28B13/00—Feeding the unshaped material to moulds or apparatus for producing shaped articles; Discharging shaped articles from such moulds or apparatus
    • B28B13/02—Feeding the unshaped material to moulds or apparatus for producing shaped articles
    • B28B13/021—Feeding the unshaped material to moulds or apparatus for producing shaped articles by fluid pressure acting directly on the material, e.g. using vacuum, air pressure
    • 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
    • B22F3/00—Manufacture of workpieces or articles from metallic powder characterised by the manner of compacting or sintering; Apparatus specially adapted therefor ; Presses and furnaces
    • B22F3/004—Filling molds with powder

Definitions

  • the present invention relates to a method of forming a shaped body from fine particles such as powder, whiskers or short fibers of ceramics or metals, by employing a mold having a mold chamber.
  • the fluidal binding agent has been considered to be indispensable to give a smooth fluidity to a mass of fine particles so that it is readily deformable to fill a mold chamber uniformly up to every corner thereof and also to maintain the shape of the molded body prior to the sintering of the fine particles.
  • US-A-3.165.570 discloses a method without using a binding agent; a carrier fluid, such as air, is used to transport the particulate material into the mold.
  • the present invention provides a method of forming a shaped body in accordance with Claim 1.
  • fine particles such as powder, whiskers or short fibers of ceramics or metal are supplied, as mixed with a carrier fluid, under a pressure elevated substantially above atmospheric pressure, into a mold chamber of a mold through an inlet port thereof open to the mold chamber at a first portion thereof, and when the mold has an outlet port open to the mold chamber at a second portion thereof substantially opposite to said first portion and adapted to exhaust substantially only the carrier fluid in a gaseous state out of the mold chamber, a continuous flow of the carrier fluid is generated across the mold chamber from the inlet port to the outlet port, whereby a suspension of the fine particles by the carrier fluid enough to carry the fine particles to every corner in the mold chamber is available, and then, as the carrier fluid which has carried the fine particles is exhausted through the outlet port, the fine particles are gradually stacked up, starting from the location of the outlet port toward the location of the inlet port, forming a tight stack of the fine particles having such a micro structure that each fine particle is most stably received in a micro space afforded by several preceding fine particles and is
  • said carrier fluid is at a super critical state when said mixture is supplied into said mold chamber, said carrier fluid being in a gaseous state at room temperature and atmospheric pressure.
  • said carrier fluid may also be at a liquid state when said mixture is supplied into said mold chamber, said carrier fluid being in a gaseous state at room temperature and atmospheric pressure.
  • said mixture may be prepared to be at said elevated pressure in a pressure vessel equipped with a heating means and an agitation means, and is supplied into said mold chamber by the pressure in said pressure vessel.
  • said mixture may be prepared in a vessel equipped with a heating means and an agitation means, and is supplied from said vessel into said mold chamber through a pump means which compresses said mixture.
  • CO2 is one of the most desirable materials to be used as said carrier fluid in the method according to the present invention.
  • 10 designates a storage container of CO2 which supplies CO2 through a conduit 12, a pump 14 and a conduit 16 to a mixing vessel 18 having a mixing chamber 20.
  • the CO2 is selectively heated by a heater 22 while it is conducted through the conduit 16.
  • the mixing vessel has a heater 24 arranged around the mixing chamber 20 and an agitator 28 for mixing fine particles 26 charged in the mixing chamber 20 and the CO2 introduced into the mixing chamber 20.
  • the mixture of the fine particles and the CO2 is conducted through a shutoff valve 30 and a conduit 32 to a mold 34 through an inlet port 36.
  • the mold 34 is made of an upper mold half 38 and a lower mold half 40 defining in combination a mold chamber 42.
  • a small clearance left between the two mold halves at a location opposite to the inlet port 36 provides an outlet port 44 adapted to pass substantially only gas therethrough.
  • a molded body was made from a silicon nitride powder by employing the device shown in Fig. 1.
  • a fine particle material consisting of a silicon nitride powder of 0.4 micron mean particle diameter forming 96 parts in weight, a yttrium oxide powder of 0.2 micron mean particle diameter forming 2 parts in weight and an alumina powder of 0.1 micron mean particle diameter forming 2 parts in weight was charged into the mixing chamber 20.
  • the agitator 28 was also operated to mix the fine particles with the super critical CO2, thus suspending the fine particles in turbulent flows of the CO2. Then, opening the shutoff valve 30, the mixture was supplied from the mixing vessel into the mold chamber 42 through the inlet port 36. In the meantime, CO2 gas was exhausted from the outlet port 44. When the mold chamber 42 was completely filled with a stack of the fine particles forming a body 46, the shutoff valve 30 was closed, and all of the heaters 22 and 24, the pump 14 and the agitator 28 were stopped.
  • the mold halves were opened and the molded body 46 in the form of a rectangular parallelopiped block such as shown in Fig. 2 was obtained.
  • the block had three dimensions precisely coinciding with those of the mold chamber 42. There was no shrinkage and no crack in the block.
  • the density and the bending strength of the molded body 46 were tested.
  • the density was substantially uniform over all portions thereof and was 1.50 g/cm3, presenting a volumetric density of 48%.
  • the molded body was firm enough to maintain its shape for subsequent sintering process. It was confirmed that no CO2 remained in the molded body.
  • the device was modified as shown in Fig. 3 so that the pump 14 is positioned in the conduit 32 and can supply a mixture of fine particles and a carrier fluid prepared in the mixing vessel 18 into the molding chamber 42 under a compression applied thereby.
  • a mixture of 10kg silicon nitride powder of 0.5 micron mean particle diameter, 500g yttrium oxide of 0.1 micron mean particle diameter and 500g alumina powder of 0.1 micron mean particle diameter was charged into the mixing chamber 20 of the mixing vessel 18. Then, with the shutoff valve 30 being kept closed, CO2 was supplied into the mixing chamber 20 at 5kg/cm2. Then, operating the heater 24, while also operating the agitator 28, the mixing chamber space was heated so that the temperature rised up to 80°C and the pressure rised up to 120kg/cm2, thus rendering the CO2 in a super critical state.
  • the shutoff valve 30 while operating the pump 14, the mixture of the fine particles and the super critical CO2 was pumped up to 300kg/cm2 and supplied to the mold chamber 20. The supply of the mixture under the pumping was continued, while allowing CO2 gas to exhaust through the outlet port 44, until the mold chamber 20 was completely filled with a stack of the fine particles. Then, the shutoff valve 30 was closed, and the pump 14 was stopped. Then, the mold halves were opened, and the mold body 46 was taken out.
  • the difference in density of the molded body according to the mixture supply pressure in the mold chamber was as follows: Pressure (kg/cm2) Density (g/cm3) 300 1.40 120 1.31 112 1.29 103 1.27 95 1.24 86 1.22 78 1.20
  • the molded body produced by the mixture supply pressure of 300kg/cm2 and the molded body produced by the mixture supply pressure of 95kg/cm2 were sintered in N2 atmosphere at 1700°C for 4 hours.
  • the density of the sintered bodies was measured.
  • 40 samples for the bending test according to JIS R1601 were produced from each molded body, and were tested.
  • the mean values of the density, the strength and the Weibull coefficient with respect to the samples obtained under the pressures of 300kg/cm2 and 95kg/cm2 were respectively as follows: Pressure Density Strength Weibull coefficient 300kg/cm2 3.27g/cm3 1260MPa 16 95kg/cm2 3.22g/cm3 920MPa 7
  • a mixture of 10kg silicon nitride powder of 0.5 micron mean particle diameter, 500g yttrium oxide powder of 0.1 micron mean particle diameter and 500g alumina powder of 0.2 micron mean particle diameter was charged into the mixing chamber 20 of the mixing vessel in the device shown in Fig. 3. Then, with the shutoff valve 30 being kept closed, CO2 under pressure was charged into the mixing chamber 20. The pressure and the temperature in the mixing chamber space were adjusted to be 100kg/cm2 and 23°C, respectively, so that the CO2 was in a liquid state. The amount of CO2 charged in the mixing chamber 20 was 3.5kg.
  • the mixture was pumped up to 200kg/cm2 and supplied into the mold chamber 42.
  • the pumping supply of the mixture into the mold chamber was continued, while CO2 gas was exhausted through the outlet port 44, until the mold chamber 42 was completely filled with a stack of the fine particles.
  • the shutoff valve was closed, the pump 14 was stopped, and the molded body was taken out from the mold in the same rectangular parallelopiped block form.
  • the molded body showed three dimensions precisely coinciding with those of the mold chamber 42.
  • the density was 1.37g/cm3. No CO2 remained in the molded body.
  • the molded body was sintered in N2 atmosphere at 1750°C for 4 hours. 40 samples for the bending test according to JIS R1601 were produced from the sintered body, and tested. The mean values of the strength and the Weibull coefficient were 1210 MPa and 14, respectively.
  • molded bodies of fine particles such as powder, whiskers or short fibers of ceramics or metal to be turned into integral ceramic or metallic articles by a subsequent sintering process are obtained to have a shape and dimensions defined by a mold chamber at high fidelity, with no use of binding agent, thereby obviating the difficulties concerned with expelling the binding agent from the molded bodies. Therefore, a high productivity is available in the manufacture of shaped articles of ceramics or metal starting from fine particles of the material.

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  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Fluid Mechanics (AREA)
  • Chemical & Material Sciences (AREA)
  • Ceramic Engineering (AREA)
  • Manufacture Of Alloys Or Alloy Compounds (AREA)
  • Powder Metallurgy (AREA)
  • Compositions Of Oxide Ceramics (AREA)

Claims (4)

  1. Verfahren zur Bildung eines Formkörpers aus feinen Partikeln, wie etwa aus Pulver, Whiskern oder Kurzfasern aus Keramiken oder Metall durch Anfertigung einer Form (34) mit einer Formkammer (42), einer zu einem ersten Abschnitt der Formkammer offenen Einlaßöffnung (36) und einer zu einem zweiten, dem ersten Abschnitt im wesentlichen gegenüberliegenden zweiten Abschnitt der Formkammer offenen Auslaßöffnung (44) und zur Zuführung eines Gemisches der feinen Partikel und eines Trägerfluids durch die Einlaßöffnung in die Formkammer bei einem wesentlich über dem atmosphärischen Druck erhöhten Druck, während das Trägerfluid über die Auslaßöffnung im gasförmigen Zustand aus der Formkammer ausströmt,
       dadurch gekennzeichnet, daß
    das Trägerfluid des über die Einlaßöffnung in die Formkammer eingespeisten Gemisches entweder im überkritischen Zustand oder im flüssigen Zustand ist, wobei sich das Trägerfluid bei Raumtemperatur und atmosphärischem Druck im gasförmigen Zustand befindet.
  2. Verfahren nach Anspruch 1, wobei das Gemisch vorbehandelt wird, um bei erhöhtem Druck in einem mit einer Heizeinrichtung (24) und einer Rühreinrichtung (28) ausgestatteten Druckkessel (18) zu sein, und mittels dem Druck im Druckkessel in die Formkammer gespeist wird.
  3. Verfahren nach Anspruch 1, wobei das Gemisch in einem mit einer Heizeinrichtung (24) und einer Rühreinrichtung (28) ausgestatteten Kessel (18) vorbehandelt wird und von dem Kessel über eine das Gemisch verdichteende Pumpeneinrichtung (14) in die Formkammer (42) gespeist wird.
  4. Verfahren nach einem der Ansprüche 1 bis 3, wobei das Trägerfluid CO₂ ist.
EP19920301994 1991-03-22 1992-03-09 Verfahren zum Formen eines Formkörpers aus feinen Teilchen mit einer Trägerflüssigkeit unter einem Druckfeld Expired - Lifetime EP0505067B1 (de)

Applications Claiming Priority (8)

Application Number Priority Date Filing Date Title
JP8361391A JPH04294102A (ja) 1991-03-22 1991-03-22 微細片の成形方法
JP83613/91 1991-03-22
JP169234/91 1991-06-14
JP3169232A JPH04368808A (ja) 1991-06-14 1991-06-14 微細片の成形方法
JP169233/91 1991-06-14
JP169232/91 1991-06-14
JP16923491A JPH04368806A (ja) 1991-06-14 1991-06-14 微細片の成形方法
JP16923391A JPH04368809A (ja) 1991-06-14 1991-06-14 微細片の成形方法

Publications (2)

Publication Number Publication Date
EP0505067A1 EP0505067A1 (de) 1992-09-23
EP0505067B1 true EP0505067B1 (de) 1995-07-19

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Application Number Title Priority Date Filing Date
EP19920301994 Expired - Lifetime EP0505067B1 (de) 1991-03-22 1992-03-09 Verfahren zum Formen eines Formkörpers aus feinen Teilchen mit einer Trägerflüssigkeit unter einem Druckfeld

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EP (1) EP0505067B1 (de)
DE (1) DE69203495T2 (de)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4314869A1 (de) * 1993-05-05 1994-11-10 Boehringer Ingelheim Kg Verfahren zur Formgebung von thermoplastischen Kunststoffen, insbesondere von resorbierbaren Thermoplasten

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3165570A (en) * 1962-08-22 1965-01-12 Alexander T Deutsch Refractory powder injection, process and apparatus
EP0446664A1 (de) * 1990-03-14 1991-09-18 Asea Brown Boveri Ag Verfahren und Vorrichtung zur Herstellung eines beliebig kompliziert geformten Bauteils durch Erzeugung eines dichtgepakten Formkörpers ausgehend von einem rieselfähigen Pulver
FR2660584A1 (fr) * 1990-04-10 1991-10-11 Rdm Ste Civile Procede et dispositif de compactage de poudres.

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Publication number Publication date
EP0505067A1 (de) 1992-09-23
DE69203495T2 (de) 1996-01-25
DE69203495D1 (de) 1995-08-24

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