WO2004096469A1 - Composition de poudres metalliques - Google Patents

Composition de poudres metalliques Download PDF

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Publication number
WO2004096469A1
WO2004096469A1 PCT/SG2004/000112 SG2004000112W WO2004096469A1 WO 2004096469 A1 WO2004096469 A1 WO 2004096469A1 SG 2004000112 W SG2004000112 W SG 2004000112W WO 2004096469 A1 WO2004096469 A1 WO 2004096469A1
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WIPO (PCT)
Prior art keywords
metal powder
particle size
metal
mean particle
powder composition
Prior art date
Application number
PCT/SG2004/000112
Other languages
English (en)
Inventor
Li Lu
Ying Hsi Jerry Fuh
Yoke San Wong
Han Tong Loh
Haihong Zhu
Yaxin Tang
Xinhua Wang
Original Assignee
National University Of Singapore
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Publication of WO2004096469A1 publication Critical patent/WO2004096469A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B33—ADDITIVE MANUFACTURING TECHNOLOGY
    • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
    • B33Y70/00—Materials specially adapted for additive manufacturing
    • 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
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/05—Metallic powder characterised by the size or surface area of the particles
    • B22F1/052—Metallic powder characterised by the size or surface area of the particles characterised by a mixture of particles of different sizes or by the particle size distribution
    • 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
    • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
    • B22F1/09—Mixtures of metallic powders
    • 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
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/20—Direct sintering or melting
    • B22F10/28—Powder bed fusion, e.g. selective laser melting [SLM] or electron beam melting [EBM]
    • 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
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/30—Process control
    • B22F10/32—Process control of the atmosphere, e.g. composition or pressure in a building chamber
    • 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
    • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
    • B22F10/30—Process control
    • B22F10/34—Process control of powder characteristics, e.g. density, oxidation or flowability
    • 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
    • B22F3/10—Sintering only
    • B22F3/105—Sintering only by using electric current other than for infrared radiant energy, laser radiation or plasma ; by ultrasonic bonding
    • B22F2003/1054—Sintering only by using electric current other than for infrared radiant energy, laser radiation or plasma ; by ultrasonic bonding by microwave
    • 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
    • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
    • B22F2998/10—Processes characterised by the sequence of their steps
    • 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
    • B22F3/10—Sintering only
    • B22F3/105—Sintering only by using electric current other than for infrared radiant energy, laser radiation or plasma ; by ultrasonic bonding
    • 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
    • B22F3/12—Both compacting and sintering
    • B22F3/14—Both compacting and sintering simultaneously
    • B22F3/15—Hot isostatic pressing
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/25—Process efficiency

Definitions

  • the present invention generally relates to a metal powder composition.
  • the present invention also relates to a metal powder composition that may be sintered and to a sintering method.
  • the material density of a metal product significantly affects its mechanical properties . Accordingly, the fabrication of 3-D metal parts using rapid prototyping methods aims to produce metal parts that are dimensionally accurate and which have a relatively high density. The fabrication of 3-D metal parts using rapid prototyping methods in which powdered metals are subjected to sintering have been investigated. However, these fabrication techniques have been hampered somewhat by the produced metal products being susceptible to warpage and low material density.
  • the apparent density of metal powders is generally within the range of 20-70%, thus it is necessary for the metal product to undergo a densification step in the metal powder forming process.
  • the densification step has resulted in shrinkage of the metal product, which may lead to warpage and reduced dimensional accuracy. Warpage can also lead to mechanical failure of objects produced from the metal powders by the rapid prototyping techniques ..
  • SLS Selective Laser Sintering
  • metal parts fabricated by these techniques may have a high density, the required laser power and beam quality are usually high.
  • the laser power is normally higher than 1 kW.
  • the process itself induces high thermal stress that may cause distortion and may limit the accuracy and size of the sintered parts .
  • DLMS direct laser metal sintering
  • WO-90/11855 One type of SLS process is called direct laser metal sintering (DLMS) and is disclosed in WO-90/11855. Although this process produced parts having high dimensional accuracy, they were found to be highly porous, having a relative density of 60-70%. Attempts have been made to increase the density of products made by this method by sintering in a gas atmosphere in the presence of a chemical compound of an iron- group metal. However, the complex equipment and control system limits the application of this technique.
  • DLMS direct laser metal sintering
  • a metal powder composition comprising: a first metal powder comprising copper and having a first mean particle size; a second metal powder comprising copper and having a second mean particle size that is less than the first mean particle size; and a third metal powder capable of at least partially melting at a temperature that is lower than the melting temperatures of the first and second metal powders and having a third mean particle size less than the first and second mean particle sizes.
  • the metal powder may be homogenous or non-homogenous .
  • the present invention provides a metal powder composition capable of being sintered comprising: a first metal powder comprising Cu or copper alloy and having a first mean particle size,- a second metal powder comprising Cu or copper alloy and having a second mean particle size that is less than the first particle size; and a third metal powder comprising copper alloy and having at least a partial melting temperature that is less than the first and second metal powders and having a third mean particle size less than the first and second mean particle sizes; wherein upon sintering, the metal powder forms a metal product having a relative density of 70% or more.
  • the present invention provides a metal powder composition
  • a metal powder composition comprising: about 30% to about 70% by weight of a first metal powder comprising Cu or copper alloy, the first metal powder having a mean particle size in the range between about 50 ⁇ m to about 90 ⁇ m; about 5% to about 20% by weight of a second metal powder comprising Cu or copper alloy, the second metal powder having a particle size in the range between about 25 ⁇ m to about 45 ⁇ m; and the remainder being substantially a third metal powder, the third metal powder having a mean particle size in the range between about l ⁇ m to about 25 ⁇ m and wherein the ratio of the melting temperature of the first and second metal powders to the melting temperature of the third metal powder is about 3 or less .
  • a method of preparing a metal powder composition comprising the steps of: providing a first metal powder comprising Cu and having a first mean particle size; providing a second metal powder comprising Cu and having a second mean particle size that is less than the first particle size; providing a third metal powder capable of at least partially melting at a temperature that is lower than the melting temperatures of the first and second metal powders and having a third mean particle size less than the first and second mean particle sizes; and combining the first metal powder, the second metal powder and the third metal powder to form the metal powder composition.
  • a sintered metal product prepared by sintering a metal powder composition, the metal powder composition comprising: a first metal powder comprising copper and having a first mean particle size; a second metal powder comprising copper and having a second mean particle size that is less than the first particle size; and a third metal powder capable of at least partially melting at a temperature that is lower than the melting temperatures of the first and second metal powders and having a third mean particle size less than the first and second mean particle sizes.
  • a sintered metal product prepared by sintering a metal powder composition, the metal powder composition comprising: a first metal powder comprising copper and having a first mean particle size; a second metal powder comprising copper and having a second mean particle size that is less than the first particle size; and a third metal powder capable of at least partially melting at a temperature that is lower than the melting temperatures of the first and second metal powders and having a third mean particle size less than the first and second mean particle sizes; wherein the metal powder composition is sintered at a pressure in the range of about 70kPa to about 120 kPa absolute pressure; wherein the metal powder composition is sintered at a temperature in the range of about 600 °C to about 1200 °C; and wherein the composition of the gas surrounding the metal powder composition as it is sintered is substantially that of air.
  • a sintering method comprising: sintering a metal powder composition comprising: a first metal powder comprising copper and having a first mean particle size; a second metal powder comprising copper and having a second mean particle size that is less than the first particle size; and a third metal powder capable of at least partially melting at a temperature that is lower than the melting temperatures of the first and second metal powders and having a third mean particle size less than the first and second mean particle sizes to provide a sintered metal product.
  • a sintered metal product prepared by the fourth aspect .
  • a metal powder composition in a sintering process, the metal powder composition comprising: a first metal powder comprising copper and having a first mean particle size; a second metal powder comprising copper and having a second mean particle size that is less than the first particle size; and a third metal powder capable of at least partially melting at a temperature that is lower than the melting temperatures of the first and second metal powders and having a third mean particle size less than the first and second mean particle sizes.
  • relative density is the ratio of the density of a sintered metal to the theoretical density of the starting powder, which is defined as follows:
  • P sner e is the density of sintered metal given as :
  • M is the mass of the sintered part
  • V is the volume of the sintered part (include porosity)
  • Ptneor e ti c ai is the theoretical density of the metal powder composition and is given as :
  • Pi is the theoretical density of the ith powder, which is 8.92 g/cm 3 for Cu at 25 °C;
  • Vi is the volume percent of the ith powder in the starting powder.
  • Appendix density generally refers to the mass (m) of a solid substance divided by its volume (v' ) (ie. m/V ) , wherein v' includes the open pores of a solid substance but excludes the closed pores of the solid substance.
  • melting temperature generally refers to the temperature at which a solid transforms into a liquid.
  • partially melting or “partial melting” and grammatical variations thereof are to be interpreted broadly to be the point at which the alloy is not completely solid but has at least begun to melt.
  • eutectic temperature generally refers to the lowest temperature at which an alloy solid will melt to form a liquid phase.
  • Incidental impurities refers to any material that may be present in the raw materials used to produce copper or an alloy that includes copper. Incidental impurities include unavoidable impurities as well as avoidable impurities .
  • Exemplary non-limiting embodiments of a metal powder composition will now be disclosed.
  • the disclosed embodiments relate to a metal powder composition that is capable of being sintered directly by a laser.
  • the disclosed embodiments describe a novel powder composition that includes a first metal powder, a second metal powder, and a third metal powder.
  • the first metal powder contains Cu or a Cu alloy and has a first mean particle size.
  • the second metal powder also contains Cu or a Cu alloy and has a second mean particle size that is less than the first particle size.
  • the third metal powder is composed of a metal or metal alloy that is capable of melting at a temperature that is lower than the melting temperatures of the first and second metal powders. Upon sintering, the metal powder forms a metal product having a relative density of 70% or more.
  • the first and second metal powders may have the same or different compositions.
  • the first and second metal powder may substantially comprise Cu and any incidental impurities.
  • the purity of the Cu may be up to 99.99% pure copper.
  • the first and second metal powder may comprise a Cu-containing alloy.
  • the amount of copper within the Cu-containing alloy may be a range by weight selected from the range consisting of: 30% to 99%, 40% to 96%, 50% to 94%, 55% to 92%, 60% to 90%, 60% to 94%, 60% to 90%, 60% to 88%, and 60% to 85%.
  • the remainder may be one or more metals and any incidental impurities .
  • the metals other than Cu that may be present in the Cu- containing alloy may be selected from the group consisting of: chromium, cobalt, lead, manganese, molybdenum, nickel, silver, tin, tungsten, zinc, and one or more mixtures thereof.
  • One or more additional additives may also be added to the Cu-containing alloy.
  • the additives may be selected from the group consisting of: aluminum, beryllium, bismuth, cadmium, carbon, iron, magnesium, niobium, phosphorous., silicon, tantalum, vanadium, zirconium and one or more mixtures thereof.
  • the amount of additives within the Cu- containing alloy may be, by weight, selected from the range consisting of: 0.02% to 4%, 0.2% to 2%, 0.2% to 1%, 0.4% to 1.5%, and 0.5% to 1%.
  • the melting temperature of the first and second metal powders may be within the range selected from the group consisting of: 900°C to 1600°C; 1000°C to 1500°C; 1100°C to 1300°C; and 1150°C to 1250°C.
  • the first and second metal powders may contain mixtures of copper and copper-containing alloy.
  • the particle size range of the first metal powder may be selected from the group consisting of: 40 ⁇ m to lOO ⁇ m; 45 ⁇ m to lOO ⁇ m; 50 ⁇ m to lOO ⁇ m; 50 ⁇ m to 95 ⁇ m; 55 ⁇ m to 90 ⁇ m; 55 ⁇ m to 85 ⁇ m; and 60 ⁇ m to 80 ⁇ m.
  • the mean particle size of the first metal powder may be in the range selected from the group consisting of: 50 ⁇ m to 90 ⁇ m; 55 ⁇ m to 85 ⁇ m; and 60 ⁇ m to 80 ⁇ m. In one embodiment, the mean particle size of the first metal powder is about 70 ⁇ m.
  • the amount of the first metal powder that may be present in the metal powder composition may be selected from the group consisting of: 30% to 70%; 40% to 70%; 40% to 65%; and 40% to 60%. In one embodiment, the first metal powder present in the metal powder composition is about 50% by weight .
  • the particle size range of the second metal powder may be selected from the group consisting of: 20 ⁇ m to 55 ⁇ m; 25 ⁇ m to 50 ⁇ m; 30 ⁇ m to 45 ⁇ m; 30 ⁇ m to 40 ⁇ m; and 35 ⁇ m to 40 ⁇ m.
  • the mean particle size of the second metal powder may be in the range selected from the group consisting of: 25 ⁇ m to 45 ⁇ m; and 30 ⁇ m to 40 ⁇ m. In one embodiment, the mean particle size of the second metal powder is about 38 ⁇ m.
  • the amount of the second metal powder that may be present in the metal powder composition may be selected from the group consisting of: 5% to 20%; 6% to 18%; 6% to 15%; and 8% to 12%.
  • the first metal powder present in the metal powder composition is about 10% by weight .
  • the third metal powder is the third metal powder
  • the third metal powder has a eutectic temperatures that is lower than the melting temperature of the first or second metal powders .
  • the composition of the third metal powder may be copper alloy having eutectic temperature less than the melting temperature of the first and second metal powders .
  • the alloy of the third metal powder may contain additional metals selected from the group consisting of: Ag, Al, Bi, B, Cd, Co, Fe, Mg, Mn, Ni, Pb, Zn, and one or more combinations thereof.
  • alloy of the third metal powder may be selected from the group consisting of: P, and Si and one or more combinations thereof.
  • Exemplary third metal alloys may include Cu-P, Cu-Ag, Cu-P-Ag, Cu-Ag-Zn, .Cu-Zn-Si, Ag-Cu-Zn-Cu.
  • the Cu-Ag-P alloy composition may be comprised as follows: about 2% to about 20% by weight Ag; about 5% to about 8% by weight P; and the remainder being Cu and any incidental impurities.
  • Exemplary Cu-Ag-P alloy compositions and their approximate melting temperatures are given in Table 1 below.
  • the melting temperature of the third powder may be within the range selected from the group consisting of: 300°C to 1000°C; 400°C to 950°C; 500°C to 900°C; 550°C to 800°C; and 600°C to 700°C.
  • the ratio of the melting temperature of the first and second metal powders to the melting temperature of the third metal powder may be about 3 or less.
  • the difference between the melting temperatures of the first and second metal powders and that of the third metal powder is in the range selected from the group consisting of: 300 °C to 900°C; 350°C to 800°C; 350°C to 700°C; and 400°C to 600°C.
  • the particle size range of the third metal powder may be selected from the group consisting of: l ⁇ m to 25 ⁇ m,- l ⁇ m to 20 ⁇ m; 5 ⁇ m to 20 ⁇ m; lO ⁇ m to 20 ⁇ m; and 12 ⁇ m to 18 ⁇ m.
  • the mean particle size of the third metal powder may be in the range selected from the group consisting of : I ⁇ m to 25 ⁇ m; lO ⁇ m to 20 ⁇ m and 12 ⁇ m to 18 ⁇ m. In one embodiment, the mean particle size of the third metal powder is about 15 ⁇ m.
  • the amount of the third metal powder that may be present in the metal powder composition may selected from the group consisting of: 23% to 60%; 25% to 65%; 30% to 60%; 30% to 50%; and 35% to 45%. In one embodiment, the third metal powder present in the metal powder composition is about 40% by weight.
  • the particles of the metal powders may be spherical or substantially spherical and/or elliptical in shape. In other embodiments, particles of the metal powders may have an irregular shape or the particles of the metal powders may be a mixture of regular and irregular shapes or the particles of the metal powders may be regular shapes .
  • the metal powders may be gas-atomized metal powders.
  • the raw materials for the metal powders to be used for the first and second metal powders may be obtained commercially from a number of manufacturers.
  • Exemplary manufacturers from which copper and copper alloy powders may be obtained include: Umicore Canada Inc., of Leduc, Alberta, Canada; ACuPowder International, LLC of Union, New Jersey, United States of America; Crucible Research LLC, of Pittsburgh, Pennsylvania, United States of America; and Kennametal Inc. of Latrobe, Pennsylvania, United States of America.
  • the raw materials for the metal powders to be used for the third metal powders may be obtained commercially from a number of manufacturers.
  • Exemplary manufacturers from which low melting temperature metal alloy powders may be obtained include: Lucas-Milhaupt Inc., of Cudahy, Wisconsin, United States of America; and Saru Silver Alloys PVT. LTD., of Meerut, Tamil Pradesh, India.
  • the first, second and third metal powders may be weighed according to the proposed metal powder composition to be prepared.
  • the weighed first, second and third metal powders may be placed into a mixing device where they may be mixed to form a substantially homogenous mixture.
  • the mixing device may be a V-Cone blender.
  • Other exemplary mixing devices include rota-cone blenders, ribbon blenders, cone blenders, kneader mixers and plough shear mixers.
  • the metal powder mixtures may be blended for in a mixing device for a period of time selected from the group consisting of: 5 minutes to 5 hours; 20 minutes to 4 hours; 30 minutes to 3 hours; 45 minutes to 2 hours; and 50 minutes to 1.5 hours.
  • the metal powder may be mixed for about 1 hour in a V-cone blender in order to obtain uniform mixture . Sintering processes
  • the metal powder composition may be densified by a sintering process .
  • Exemplary sintering process that may be used to sinter the disclosed metal powder composition include laser sintering, selective laser sintering or hot isostatic pressing, direct laser sintering, thermal sintering and microwave sintering.
  • the sintering may be carried out at an absolute pressure in the range selected from the group consisting of: 70 kPa to 120 kPa; 75 kPa to 115 kPa; 80 kPa to 110 kPa; 90 kPa to 105 kPa; and 95 kPa to 105 kPa. In one embodiment, the sintering is carried out at a pressure of about 101.3 kPa.
  • the sintering may be carried out at temperature in the range selected from the group consisting of: 600 °C to about 1200°C; 625°C to about 1100°C; 650°C to 1000°C; 650°C to 900°C; and 650°C to 800°C.
  • the sintering may be carried out in the presence of oxygen in the range, by volume, selected from the group consisting of:l% to 25%; 5% to 21%; 10% to 21%; 15% to 21%; and 18% to 21%. In one embodiment, the sintering may be carried out in the presence of air.
  • the metal powder composition may be sintered directly by a laser.
  • the power of the laser applied directly to the metal powder composition may be in the range selected from the group consisting of: 75W to 400W; 100W to 300W; 100W to 250W.
  • the metal powder composition may be sintered directly by a laser at about 200W.
  • the laser may be scanned over the surface of a layer of the metal powder composition.
  • the scan speed of the laser may be in the range selected from the group consisting of: 50 to 500mm/s; 75 to 400mm/s; 100 to 300mm/s; and 150 to 250mm/s. In one embodiment, the scan speed of the laser is about 200 mm/s .
  • the laser scan spacing may be in the range selected from the group consisting of: 0.05mm to 0.4mm; 0.1mm to 0.3mm; and 0.15mm to 0.25mm. In one embodiment, the scan speed of the laser is about 0.2 mm.
  • the layer thickness of the metal powder composition that may be subjected to direct laser sintering may be in the range selected from the group consisting of: 0.05mm to 0.2mm;
  • the scan speed of the laser is about 0.075 mm.
  • the relative density of the metal product may be in the range selected from the group consisting of: 70% to 100%; 75% to 98%; 78% to 95%; 80% to
  • FIG. 1 is shows a schematic diagram of an apparatus used in the direct laser sintering process
  • Fig. 2 shows the Simultaneous Thermal Analysis (STA) traces of the third powder mixture of Example 1 and pure Cu;
  • Fig. 3 shows the surface morphology of a sintered sample of the composition prepared in example 1;
  • Fig. 4 shows the microstructure of the sintered sample of the composition prepared in example 1;
  • Fig. 5 shows a Scanning Electron Microscope (SEM) image of the sintered sample of the composition prepared in example
  • Fig. 6(a) shows X-ray patterns of the starting powder composition prepared in example 1;
  • Fig. 6(b) shows X-ray patterns of a sintered sample of the composition prepared in example 1;
  • Fig. 7 shows a hypothetical model of expansion in plate caused by gravity in direct laser sintering.
  • Fig. 1 shows a schematic diagram of the operation of a laser sintering system 10 that can be used to sinter the metal powder composition.
  • the system 10 includes a continuous-wave (CW) C0 2 laser 12 operating at a wavelength ( ⁇ ) equal to 10.6 ⁇ m and at 200W power.
  • the system 10 also includes a chamber 14 having a controlled atmosphere.
  • the system 10 also includes a metal powder composition delivery system 16 that includes a powder chamber 18 for holding the metal powder composition, a drive plate 20 at the base of the chamber 18 for moving the metal powder composition in the direction of arrow 22, and a scrapper 24 at the top of the powder chamber 18 for moving a layer of metal powder composition 26 in the direction of arrow 28, towards laser chamber 30.
  • Laser chamber 30 is initially charged with the metal powder composition.
  • the system 10 also includes a lens 32 in the optical path of laser light being emitted from the laser 12 for focussing the laser light onto scanner 34.
  • the focus of the lens 32 is 370mm with a focused spot size of 0.3mm.
  • the scanner 34 is also provided along the optical path of the laser light and directs the laser light to the surface of the metal powder composition charged within laser chamber 30.
  • the scanner 34 is capable of operating at variable scanning speed.
  • a preheating device 38 capable of preheating the metal powder within chamber 30 is provided to pre-heat the metal powder to a maximum temperature of 400 °C as a layer of the metal powder composition is passed from scrapper 24 to chamber 30.
  • the system 10 is operable by a controller in the form of a computer (not shown) , the implementation of which is known in the art .
  • Software loaded onto the computer operates the scrapper 24 to move a slice of the metal powder composition over pre-heater 38 and then onto the top surface of chamber 30.
  • the scanner 34 then passes over the surface of the metal powder composition and causes the metal powder composition to sinter and form a metal.
  • the laser 32 is operated in an on/off mode as the scanner 34 passes over the surface of the metal powder in chamber 30 according to, the desired metal part being built (metal part 36) .
  • the operation of the laser 12 and the scanner 34 is controller by the computer with data stored within its software to automatically control the laser scanning and mechanical operation of the system 10.
  • the dimensional accuracy of a sintered metal part is a very important issue in direct laser sintering process .
  • the accuracy of the sintered parts is mainly determined by the shrinkage of the material and process parameters of the sintering machine and its associated control system.
  • the metal powders used in direct laser sintering are in the form of a "loose" powder that generally have an apparent density of 20-70%.
  • the metal powder composition undergoes densification and, in view of the low relative density, it would be expected that the densified material will undergo significant shrinkage.
  • Fig. 7 there is shown a proposed schematic diagram model of expansion in plate caused by gravity in direct laser sintering for the metal powder composition of the disclosed embodiments. It has been found that the density of the metal powder can be enhanced by mixing the different sized metal powders .
  • FIG. 7 shows a schematic diagram of a first metal powder (particle 1 and particle 2) , second metal powder (particle 3)and third metal powder (particle 4).
  • the role of gravity is shown in Figure 7.
  • the metal particle 3 falls down since metal particle 4 forms a liquid during direct laser sintering.
  • the metal particle 3 pushes the metal particle 1 and 2. If the diameter of metal particle 3 is larger than the distance between metal particles 1 and 2, shrinkage in the height (X) direction and expansion "in plane” occurs (ie in plane is width (W) and length (L) direction; Fig. 7 only shows (X) and (W) ) .
  • the direct laser sintering process is a layer by layer process
  • the shrinkage in the X direction is compensated by the subsequently deposited metal powder layer that is sintered.
  • W and L in-plane shrinkage
  • relative densities of more than 70% for copper metal parts have been obtained. More advantageously, relative densities of between 80-90% for copper metal parts have been obtained using direct laser sintering.
  • the Cu powders were obtained from Sulzer Metco (Singapore) Pte Ltd of Singapore.
  • Powders 1, 2 and 3 were blended in the V-Cone blender for 120 minutes to obtain a homogenous mixture.
  • the composition of the metal powder is given in Table 2 below.
  • the mixed metal powder composition was sintered directly in a laser using a High Temperature Laser Manufacturing System (HTLMS) that has been developed by the National University of Singapore.
  • HTLMS High Temperature Laser Manufacturing System
  • the mixed metal powder composition was then subjected to laser sintering by the HTMLS using a laser operating at 200W, a scan speed of 240 mm/s, scan spacing of 0.2mm and a layer thickness of 0.075mm.
  • the sintering occurred in an atmospheric atmosphere, that is in air where the oxygen content is about 21% by volume and the reminder being substantially nitrogen and any other gasses normally present in air.
  • STA Simultaneous Thermal Analysis
  • Fig. 2 shows STA traces of powder 3 and pure Cu.
  • the STA traces shown in Fig. 2 indicate that the melting point of powder 3 is 646°C and that of pure Cu is 1083 °C. No reactions occurred during heating.
  • FIG. 4 there is shown a microstructure of the sintered sample of the composition prepared in example 1.
  • Fig. 4 shows clear structural metal particles and surrounding binder, suggesting that the bonding mechanism is liquid phase sintering.
  • Fig. 5 shows a Scanning Electron Microscope (SEM) image of the sintered sample of the composition prepared in example 1.
  • the image shows the interface of Cu particles from powders 1 and 2 and the powder 3 acting as a binder.
  • the integrity of Cu grain boundary and the compact bonding between the Cu particles and the SCuP binder indicates good wetting between the particles.
  • Fig. 6(a) shows an X-ray pattern of the starting powder composition of example 1.
  • Fig. 6(b) shows an X-ray pattern of the sintered sample .
  • a comparison of the two X-Ray patterns indicates that no oxidization occurred during the sintering.
  • the relative density of the metal produced in experiment 1 was found to be 74.3%.
  • Example 2 10 kg of a metal powder composition capable of being sintered directly by a laser was prepared as follows :
  • Powders 1, 2 and 3 were mixed in a V-Cone blender for 120 minutes.
  • the relative density of the metal produced in experiment 2 was found to be 77.1%.
  • Table 3 shows the shrinkage in scan direction (ie shrinking in plane) of the metal powder of the Comparative Example and that of Example 2.
  • the disclosed embodiments provide a metal powder composition that is capable of being sintered to produce a three-dimensional metal product that has a density of 70% or more.
  • the disclosed metal powder composition is capable of being sintered and used in the fabrication of metallic parts. Upon sintering the disclosed metal powder composition, the fabricated parts are shown to have high relative density and to have relatively minimal in-plane shrinkage or less shrinkage compared to that of known metal powder compositions .
  • the disclosed metal powder composition is capable of being sintered using a relatively low powered laser.
  • the disclosed metal powder composition can be direct sintered using only the relatively low powered laser.
  • the use of relatively a low powered laser reduces the cost of direct laser sintering compared to other methods that utilize high powered laser for sintering.
  • the method and system that utilizes the disclosed metal powder to produce metal products may automatically compensate for sintering shrinkage without sacrificing the product density.
  • the disclosed metal powder is also capable of being sintered under ambient atmospheric conditions .
  • the disclosed metal powder is also capable of being sintered without any pre-heating.

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Abstract

L'invention concerne une composition de poudres métalliques, pouvant être utilisée comme matériau dans un procédé de frittage. Cette composition comprend une première poudre métallique qui contient du cuivre et présente une première taille de particule moyenne; une deuxième poudre métallique qui contient du cuivre et présente une deuxième taille de particule moyenne inférieure à la première taille de particule moyenne; une troisième poudre métallique pouvant fondre à une température inférieure aux températures de fusion de la première et de la deuxième poudre métallique et présentant une troisième taille de particule moyenne inférieure à la première et à la deuxième taille de particule moyenne.
PCT/SG2004/000112 2003-04-29 2004-04-29 Composition de poudres metalliques WO2004096469A1 (fr)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130087605A1 (en) * 2011-10-06 2013-04-11 Fujitsu Limited Conductive bonding material, conductor bonding method, and semiconductor device production method
US20200180081A1 (en) * 2013-04-29 2020-06-11 Nuburu, Inc. Applications, methods and systems for materials processing with visible raman laser
US10773310B2 (en) * 2017-01-31 2020-09-15 General Electric Company Additive manufacturing system, article, and method of manufacturing an article
EP4268996A1 (fr) * 2022-04-29 2023-11-01 EOS GmbH Electro Optical Systems Mélanges pulvérulents pour fabrication additive ayant une densité accrue

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3881914A (en) * 1974-04-26 1975-05-06 Owens Illinois Inc Preparation of electronic grade copper
WO2002060623A2 (fr) * 2001-01-31 2002-08-08 Crompton Corporation Preparation de cuivre et de composes de cuivre nanometriques
US20040009089A1 (en) * 2002-07-12 2004-01-15 Jianxin Liu Blended powder solid-supersolidus liquid phase sintering

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3881914A (en) * 1974-04-26 1975-05-06 Owens Illinois Inc Preparation of electronic grade copper
WO2002060623A2 (fr) * 2001-01-31 2002-08-08 Crompton Corporation Preparation de cuivre et de composes de cuivre nanometriques
US20040009089A1 (en) * 2002-07-12 2004-01-15 Jianxin Liu Blended powder solid-supersolidus liquid phase sintering

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20130087605A1 (en) * 2011-10-06 2013-04-11 Fujitsu Limited Conductive bonding material, conductor bonding method, and semiconductor device production method
US20200180081A1 (en) * 2013-04-29 2020-06-11 Nuburu, Inc. Applications, methods and systems for materials processing with visible raman laser
US10773310B2 (en) * 2017-01-31 2020-09-15 General Electric Company Additive manufacturing system, article, and method of manufacturing an article
EP4268996A1 (fr) * 2022-04-29 2023-11-01 EOS GmbH Electro Optical Systems Mélanges pulvérulents pour fabrication additive ayant une densité accrue
WO2023209190A1 (fr) * 2022-04-29 2023-11-02 Eos Gmbh Electro Optical Systems Mélanges de poudres pour fabrication additive à densité accrue

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