Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y80/00—Products made by 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
  • 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
  • B22F10/36—Process control of energy beam parameters
  • B22F10/364—Process control of energy beam parameters for post-heating, e.g. remelting
• • 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
  • B22F10/36—Process control of energy beam parameters
  • B22F10/366—Scanning parameters, e.g. hatch distance or scanning strategy
• • 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
  • B22F12/00—Apparatus or devices specially adapted for additive manufacturing; Auxiliary means for additive manufacturing; Combinations of additive manufacturing apparatus or devices with other processing apparatus or devices
  • B22F12/40—Radiation means
  • B22F12/41—Radiation means characterised by the type, e.g. laser or electron beam
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C1/00—Making non-ferrous alloys
  • C22C1/04—Making non-ferrous alloys by powder metallurgy
  • C22C1/0425—Copper-based alloys
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C9/00—Alloys based on copper
• • 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
  • B22F2301/00—Metallic composition of the powder or its coating
  • B22F2301/10—Copper
• • 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
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y10/00—Processes of additive manufacturing
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y70/00—Materials specially adapted for additive manufacturing
• • 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 relates to additive manufacturing by powder bed deposition and selective melting of a copper object.
• the invention aims to allow the additive manufacturing of copper objects having a material density greater than 99%.
• Copper is used in many applications for its high thermal conductivity and/or its high electrical conductivity. For example, copper is very frequently used for making electrical connections inside all kinds of electrical appliances.
• the high reflectivity of copper to light and its high thermal conductivity do not favor the implementation of additive manufacturing by powder bed deposition and selective melting with a laser beam.
• the high reflectivity of copper greatly reduces the energy transmitted by the laser beam to the powder layer, and on the other hand, its high thermal conductivity promotes the dissipation of heat in the powder layer by conduction and therefore impairs the quality of the molten pool.
• the objects made with these copper alloys can be suitable in certain applications, there are also applications, in particular electrical, in which these objects cannot be used or will not offer the desired performance because the added metals, chromium or molybdenum, reduce the electrical conductivity of the manufactured object.
• the present invention aims to allow the manufacture of copper objects by an additive manufacturing process by powder bed deposition and selective melting and from a metal powder comprising at least 95% by mass of copper .
• the document FR2980380 proposes a strategy for the additive manufacturing of a metal part by powder bed deposition and selective melting which comprises, for each layer of the part produced, at least two successive scans of the same zone of the layer of powder with a laser beam or an electron beam.
• this double scan makes it possible to better control the manufacturing process, to reduce the risks of cracking and to generate layers of material of greater density without causing excessive thermal gradients, as well as to homogenize the material of the parts thus manufactured.
• This document FR2980380 refers to René 77 alloys, TiAl or a nickel-based superalloy, but it does not address the manufacture of copper objects. [0012] Surprisingly, it has been discovered by the inventor that the use of a double scan as described in the document FR2980380 allows the additive manufacturing of copper objects from a metal powder. comprising at least 95% by mass of copper and allows the manufacture of copper objects having a material density greater than 99%.
• the invention relates to a process for the additive manufacturing of a copper object, the process being an additive manufacturing process by powder bed deposition and selective melting, said object being manufactured by the selective melting of layers of powder superimposed on a support, the selective fusion of a layer of powder being obtained by the displacement, called scanning, of a laser beam on the said layer of powder, the powder used by the method being metallic and comprising at least 95 % by mass of copper.
• each area to be merged of each layer of powder is scanned at least twice by the laser beam, the first scanning of the laser beam making it possible to create a film of nanoparticles on the surface of the powder present in each area. to be merged, this film of nanoparticles reducing the reflectivity of the powder in each zone to be merged, and the second sweep of the laser beam merging the powder in each zone to be merged thanks to the presence of the film of nanoparticles created by the first sweep.
• the invention may also provide that:
• the two scans of each zone to be merged are carried out with a laser beam whose wavelength is between 1030 nm and 1100 nm, more precisely between 1050 nm and 1090 nm, and preferably between 1060 nm and 1080 nm,
• the first scan is performed in conductive mode and the second scan is performed in "keyhole" mode
• the inter-vector space during the second scan is equal to or less than the inter-vector space during the first scan
• the inter-vector space during the second scan is between 50% and 80% of the inter-vector space during the first scan
• the spot size of the laser beam is larger during the first scan than during the second scan
• the spot size of the laser beam during the first scan is between 120% and 140% of the spot size of the laser beam during the second scan
• the vectors of the second scan are parallel to the vectors of the first scan and interleaved with respect to the vectors of this first scan
• each scan of each zone to be merged comprising parallel vectors, the vectors of the second scan are not parallel to the vectors of the first scan,
• the power of the laser beam used for the first scan is greater than or equal to the power of the laser beam used for the second scan
• the power of the laser beam used for the first scan is between 115% and 140% of the power of the laser beam used for the second scan
• the speed of movement of the spot of the laser beam used for the first scan is greater than or equal to the speed of movement of the spot of the laser beam used for the second scan
• the displacement speed of the spot of the laser beam used for the first scan is between 110% and 150% of the displacement speed of the spot of the laser beam used for the second scan
• the inter-vector space in the second scan is smaller than the inter-vector space in the first scan, while the laser beam spot size, laser beam power and laser beam spot moving speed are identical in both scans.
• the invention relates to a process for the additive manufacturing of a copper object from a metal powder comprising at least 95% by mass of copper. More particularly, the invention aims to allow the additive manufacturing of a copper object having a density of material greater than or equal to 99.6%.
• the material density of a manufactured object is directly linked to the quality of the weld pool and to the porosities created in the object by the use of selective melting.
• an object with a density of matter equal to 100% contains no porosity
• an object with a density of matter equal to 90% contains 10% by volume of porosities, that is to say interstices filled gas and not solid matter. It is generally sought to avoid porosities because they reduce the mechanical characteristics of the manufactured object as well as its electrical and thermal conductivities.
• the material density of a manufactured object is preferably measured by destructive cutting of the object then polishing and image analysis (measurement of the ratio: holes/solid material).
• the material density of a manufactured object can be measured by tomography, with Archimedes' principle or with a pycnometer.
• the process used is an additive manufacturing process by powder bed deposition and selective melting.
• Additive manufacturing by powder bed deposition and selective fusion is an additive manufacturing process in which one or more objects are manufactured by the selective fusion of different layers of additive manufacturing powder superimposed on each other.
• the first layer of powder is deposited on a support such as a plate, then selectively fused using one or more sources of energy or heat along a first horizontal section of the object or objects to be manufactured.
• a second layer of powder is deposited on the first layer of powder which has just been merged, and this second layer of powder is in turn selectively merged, and so on until the last layer of powder useful for the manufacture of the last horizontal section of the object(s) to be manufactured.
• the selective melting of a layer of powder is obtained by the movement, called scanning, of at least one laser beam on said layer of powder.
• the method according to the invention aims in particular to allow the manufacture of copper objects with a laser beam whose wavelength is between 1030 nm and 1100 nm, more precisely between 1050 nm and 1090 nm, and preferably between 1060 nm and 1080 nm.
• a laser beam whose wavelength is between 1030 nm and 1100 nm offers a greater focal length and therefore the possibility of making objects of larger dimensions.
• a laser beam whose length wavelength is between 1030 nm and 1100 nm offers a larger diameter, and therefore greater productivity, than a laser beam of shorter wavelength, and located for example around 532 nm.
• the reflectivity of a laser beam whose wavelength is between 1030 nm and 1100 nm is greater than the reflectivity of a laser beam whose length d
• the wave is shorter and is for example around 532 nm. Therefore, the longer wavelength laser beam has a lower absorption rate and transmits less energy to the copper powder than the shorter wavelength laser beam.
• the method according to the invention aims in particular to overcome this drawback and to allow the manufacture of copper objects with a laser beam whose wavelength is between 1030 nm and 1100 nm.
• the method according to the invention provides that each zone to be merged of each layer of powder is scanned at least twice by the laser beam, the first scanning of the laser beam making it possible to create a film of nanoparticles on the surface of the powder present in each zone to be merged, this film of nanoparticles reducing the reflectivity of the powder in each zone to be merged, and the second scan of the laser beam merging the powder in each zone to be merged thanks to the presence of the film of nanoparticles created by the first scan.
• the film of nanoparticles created by the first scanning of the laser beam is a thin layer of nanoparticles, at least partially covering the layer of powder to be fused.
• a zone to be merged of a layer of powder is a zone corresponding to the section of an object to be manufactured in this layer of powder or to the section of a support of an object to be manufactured in this layer of powder.
• the first scanning of an area to be merged by the laser beam has the main objective of creating the film of nanoparticles.
• the powder is partially fused following this first scan.
• this partial fusion of the powder following the first scan does not harm the quality of the fusion generated by the second scan, in particular because nanoparticles are also present on the partially fused powder.
• the film of nanoparticles makes it possible to reduce the reflectivity of the powder by increasing the roughness of the surface of the powder layer. This increase in roughness results in an increase in the number of cavities on the surface of the powder which make it possible to trap the photons of the laser beam and therefore to improve the transfer of energy between the laser beam and the powder during the second scan. As it makes it possible to trap the photons and therefore the light from the laser beam, the film of nanoparticles also has a darker color than the powder it covers.
• the nanoparticles have a particle size approximately 1000 times smaller than the particle size of the powder used in the process according to the invention.
• the nanoparticles have a particle size between 25 and 75 nm.
• the nanoparticles can be isolated or agglomerated with each other. In the case where the nanoparticles are agglomerated together, they always make it possible to reduce the reflectivity of the powder.
• the first scan is performed in conductive mode.
• the method according to the invention therefore implements a first step, namely the first scan, the result of which is generally considered a failure due to the poor quality of fusion of the powder.
• the increase in the roughness of the powder obtained with the first scan makes it possible to reduce the reflectivity of the powder and therefore to guarantee the good quality of the fusion during the second scan by improving the absorption rate. of the energy of the laser beam by the powder during this second scan.
• a copper object obtained with the additive manufacturing process according to the invention has a material density greater than or equal to 99.6%.
• the two scans of each zone to be merged are carried out with a laser beam whose wavelength is between 1030 nm and 1100 nm, more precisely between 1050 nm and 1090 nm, and preferably between 1060 nm and 1080 nm.
• the method according to the invention can also be implemented with a laser beam whose wavelength is shorter and is for example around 532 nm. In this case, the method according to the invention will serve above all to increase productivity.
• the second scan of each zone to be merged is performed in “keyhole” mode.
• each scan of each zone to be merged comprises parallel vectors.
• These parallel vectors are for example arranged at regular intervals from each other, this interval being called inter-vector space.
• This scanning technique is known in particular by the term “hatching” or hatching.
• the inter-vector space during the second scan is equal to or less than the inter-vector space during the first scan.
• the first scan can be performed with larger inter-vector spaces, for example to reduce the time spent on this first scan.
• the inter-vector space during the first scan is between 100 and 300 ⁇ m, and preferably between 150 ⁇ m and 200 ⁇ m.
• the inter-vector space during the second scan is between 50% and 80% of the inter-vector space during the first scan.
• the vectors of the second scan are for example parallel to the vectors of the first scan and interlaced with respect to the vectors of this first scan.
• a vector of the second scan is interleaved with the vectors of the first scan when this vector of the second scan lies between two vectors of the first scan.
• a vector of the second scan is between two vectors of the first scan and equidistant from these two vectors of the first scan.
• each scan of each zone to be merged comprises parallel vectors
• the vectors of the second scan may not be parallel to the vectors of the first scan. In this case, there is therefore an angular offset between the vectors of the first scan and the vectors of the second scan.
• the power of the laser beam used for the first scan is greater than or equal to the power of the laser beam used for the second scan.
• the power of the laser beam used for the two scans is between 700 and 1000 W.
• the power of the laser beam used for the first scan is at least equal to 800 W.
• the power of the laser beam used for the first scan is between 115% and 140% of the power of the laser beam used for the second scan.
• the speed of movement of the spot of the laser beam used for the first scan is greater than or equal to the speed of movement of the spot of the laser beam used for the second scan.
• these movement speeds are between 300 and 1000 m/s.
• the speed of movement of the spot of the laser beam used for the first scan is between 110% and 150% of the speed of movement of the spot of the laser beam used for the second scan.
• the spot size of the laser beam is larger during the first scan than during the second scan.
• the spot size of the laser beam during a scan can be between 100 ⁇ m and 200 ⁇ m, and is preferably between 120 and 180 ⁇ m.
• the size of the spot of the laser beam is for example measured on the layer of powder to be fused.
• the spot size of the laser beam during the first scan is between 120% and 140% of the spot size of the laser beam during the second scan.
• the size of the spot of the laser beam is its diameter when this spot is circular or corresponds to the largest dimension of this spot when it takes another shape.
• the inter-vector space during the second scan is less than the inter-vector space during the first scan, and the spot size of the laser beam, the power of the laser beam and the displacement speed of the spot of the laser beam are identical during the two scans.
• the present invention also covers a copper object manufactured additively with the method which has just been described, the object being manufactured layer by layer and having a material density greater than or equal to 99.6%.
• a copper object manufactured additively with the process according to the invention offers a metallurgical structure specific to objects manufactured additively and distinguishing itself from the metallurgical structure of copper objects manufactured by other processes such as foundry or forging for example. For example, when cutting an object made additively layer by layer in a plane perpendicular to these layers, it is possible to distinguish, with the appropriate equipment, the different superimposed layers and the fusion beads.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Materials Engineering (AREA)
• Manufacturing & Machinery (AREA)
• Plasma & Fusion (AREA)
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• Automation & Control Theory (AREA)
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• 2021
  • 2021-09-27 FR FR2110152A patent/FR3127422B1/fr active Active
• 2022
  • 2022-09-19 CN CN202280060590.XA patent/CN117940237A/zh active Pending
  • 2022-09-19 WO PCT/FR2022/051754 patent/WO2023047044A1/fr not_active Ceased
  • 2022-09-19 EP EP22789956.4A patent/EP4408601A1/de not_active Withdrawn
  • 2022-09-19 US US18/695,197 patent/US20240390979A1/en active Pending

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