Classifications

• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C24/00—Coating starting from inorganic powder
  • C23C24/08—Coating starting from inorganic powder by application of heat or pressure and heat
  • C23C24/10—Coating starting from inorganic powder by application of heat or pressure and heat with intermediate formation of a liquid phase in the layer
  • C23C24/103—Coating with metallic material, i.e. metals or metal alloys, optionally comprising hard particles, e.g. oxides, carbides or nitrides
• • 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
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K10/00—Welding or cutting by means of a plasma
  • B23K10/02—Plasma welding
  • B23K10/027—Welding for purposes other than joining, e.g. build-up welding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K15/00—Electron-beam welding or cutting
  • B23K15/0046—Welding
  • B23K15/0086—Welding welding for purposes other than joining, e.g. build-up welding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K15/00—Electron-beam welding or cutting
  • B23K15/0046—Welding
  • B23K15/0093—Welding characterised by the properties of the materials to be welded
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K15/00—Electron-beam welding or cutting
  • B23K15/10—Non-vacuum electron beam-welding or cutting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/12—Working by laser beam, e.g. welding, cutting or boring in a special environment or atmosphere, e.g. in an enclosure
  • B23K26/126—Working by laser beam, e.g. welding, cutting or boring in a special environment or atmosphere, e.g. in an enclosure in an atmosphere of gases chemically reacting with the workpiece
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/12—Working by laser beam, e.g. welding, cutting or boring in a special environment or atmosphere, e.g. in an enclosure
  • B23K26/127—Working by laser beam, e.g. welding, cutting or boring in a special environment or atmosphere, e.g. in an enclosure in an enclosure
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/34—Laser welding for purposes other than joining
  • B23K26/342—Build-up welding
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/36—Removing material
  • B23K26/38—Removing material by boring or cutting
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B23—MACHINE TOOLS; METAL-WORKING NOT OTHERWISE PROVIDED FOR
  • B23K—SOLDERING OR UNSOLDERING; WELDING; CLADDING OR PLATING BY SOLDERING OR WELDING; CUTTING BY APPLYING HEAT LOCALLY, e.g. FLAME CUTTING; WORKING BY LASER BEAM
  • B23K26/00—Working by laser beam, e.g. welding, cutting or boring
  • B23K26/60—Preliminary treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—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
  • B29C64/10—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
  • 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
  • B33Y30/00—Apparatus for additive manufacturing; Details thereof or accessories therefor
• • 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
  • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
  • B22F10/70—Recycling
  • B22F10/73—Recycling of powder
• • 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
  • B22F12/10—Auxiliary heating means
  • B22F12/13—Auxiliary heating means to preheat the material
• • 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
  • B22F12/10—Auxiliary heating means
  • B22F12/17—Auxiliary heating means to heat the build chamber or platform
• • 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
  • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
  • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
  • B29C64/00—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
  • B29C64/30—Auxiliary operations or equipment
  • B29C64/307—Handling of material to be used in additive manufacturing
  • B29C64/314—Preparation
• • 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 methods and apparatuses adapted to perform additive manufacturing (AM) processes and the resulting products made therefrom, and specifically, to AM processes that employ an energy beam to selectively fuse a material to produce an object. More particularly, the invention relates to methods and systems that use reactive fluids to actively manipulate the surface of a material prior to and/or during the AM process.
• AM additive manufacturing
• AM processes also referred to as three dimensional printing
• AM processes involve the fabrication of a three-dimensional object through the deposition of successive layers of material to make a net or near net shape (NNS).
• NPS net or near net shape
• AM encompasses various manufacturing and prototyping techniques known under a variety of names, including freeform fabrication, 3D printing, rapid prototyping/tooling, etc. AM techniques are capable of fabricating complex components from a wide variety of materials.
• AM process uses an energy beam, for example, an electron beam or electromagnetic radiation such as a laser beam, to sinter or melt a material, such as a powder, rod, wire or liquid, creating a solid three-dimensional object in which particles of the powder material are bonded together.
• energy beam for example, an electron beam or electromagnetic radiation such as a laser beam
• SLM selective laser melting
• DMLS direct metal laser sintering
• SLS selective laser sintering
• FDM fused deposition modeling
• FFF fused filament fabrication
• DPF powder bed and inkjet head 3D printing
• SLS is a notable AM process for rapid fabrication of functional prototypes and tools by using a laser beam to sinter or melt a fine powder. More accurately, sintering entails fusing (agglomerating) particles of a powder at a temperature below the melting point of the powder material, whereas melting entails fully melting particles of a powder to form a solid homogeneous mass.
• the physical processes associated with laser sintering or laser melting include heat transfer to a powder material and then either sintering or melting the powder material.
• the laser sintering and melting processes can be applied to a broad range of powder materials, the scientific and technical aspects of the production route, for example, sintering or melting rate and the effects of processing parameters on the microstructural evolution during the layer manufacturing process have not been well understood.
• This method of fabrication is accompanied by multiple modes of heat, mass and momentum transfer, and chemical reactions on the surface of the powder material that make the process very complex.
• LAM Low-power additive
• the various forms of LAM offer great potential for fabricating and repairing complex objects, they are limited by certain disadvantages which often inhere to the use of powder materials.
• One disadvantage relates to the reactivity of the surface of the powder materials with components in air such as oxygen and nitrogen.
• the powdered materials comprise reactive metals such as iron, aluminum and titanium the surface of these metallic particles can react with air to form microstructural defects (e.g., voids, impurities, or inclusions) in the final product.
• microstructural defects e.g., voids, impurities, or inclusions
• the impurities include metal oxides, and metal nitrides, and the rate of such defects whether impurities, voids or inclusions generally increases as the surface area of the powdered materials increase.
• Powder materials also tend to readily adsorb moisture which in the case of metallic powders results in the formation of metal oxides and may also lead to unwanted porosity in metallic objects formed using laser powder deposition.
• the moisture is also a source of hydrogen that forms on the powders' surface and within the fabricated product resulting in delayed cracking or hydrogen embrittlement.
• the melt pool resulting from laser powder deposition is often shielded by applying an inert gas, such as argon and helium.
• an inert gas such as argon and helium.
• post-deposition processes such as hot isostatic pressing (HIP) are also often used to collapse pores (voids), inclusions and cracks in order to improve the properties of laser-deposited metals.
• HIP hot isostatic pressing
• Such protective and post-processing measures are particularly important for metallic powders containing highly reactive metals (e.g., superalloys) and for fine powders having high surface areas.
• Pre-treatment may include coating, degassing and heat treating the powder.
• Degassing can be used to remove water vapor from the powder particles. Surfaces of the powder can become oxidized very quickly during the manufacturing process when exposed to the environment. Water vapor can absorb into the oxide, which can cause voids in the material formed with the additive manufacturing process. Methods of removing water from the manufactured materials can cause the forming of hydrogen which can make the final material more brittle. Previous methods of removing water vapor from the powder include various methods of degassing. For example, Chinese patent No.
• CN105593185A describes a way to produce low-oxygen containing metallic Ti powders by utilizing hydrogen atmosphere and the hydrogen embrittlement. However, avoiding reactions with oxygen result in safe delivery/handling complications because low-oxygen containing metallic powders are highly explosive.
• an improved system for laser additive manufacturing is necessary which allows for active manipulation of the surface of a material prior to and/or during the additive manufacturing process by introduction of one or more reactive fluids or fluid mixtures that react with the surface of the base material, such as but not limited to a powder, plasma, rod, wire or liquid, being deposited such that different portions of the deposited base material can be made to possess different base material properties.
• a reactive fluids or fluid mixtures that react with the surface of the base material, such as but not limited to a powder, plasma, rod, wire or liquid, being deposited such that different portions of the deposited base material can be made to possess different base material properties.
• the present invention provides a method and apparatus suitable for use in AM (additive manufacturing) techniques, wherein a reactive fluid is contacted with a base material, such as but not limited to a powder, plasma, rod, wire or liquid wherein the reactive fluid modifies the surface of the base material to have a desired chemistry prior to, during or after the application of an energy beam which is used to selectively sinter (fuse) or melt the base material to produce a 3D object.
• a base material such as but not limited to a powder, plasma, rod, wire or liquid
• the reactive fluid modifies the surface of the base material to have a desired chemistry prior to, during or after the application of an energy beam which is used to selectively sinter (fuse) or melt the base material to produce a 3D object.
• the chemical composition of the surface of the base material is controlled/reformed/modified before, during and/or after the AM process by introduction of one or more reactive fluids or fluid mixtures that chemically react with the surface of the base material.
• Fluids including gas mixtures containing hydrogen, carbon monoxide or other gas components that chemically reduce surface oxides and/or otherwise clean or remove impurities on the surface of materials such as solid powders are used instead of or in addition to pure purge gases (e.g. He, Ar or N 2 ) in the chamber itself, as well as in the metallic-powder-delivery line, the metallic- powder-delivery container, or in the used-metallic-powder receiver.
• the present invention includes the treatment of the material by a gas or gases including gas mixtures could be employed to recycle, for example, used metallic powders, which leads to the cost reduction of powders.
• gases with higher thermal conductivity e.g. He
• the gases with higher thermal conductivity could be employed as a purge gas or a balance gas, which is effective to reduce the residual stress derived from temperature gradients.
• the present invention may further employ gases including gas mixtures to remove hydrogen in the base materials or fabricated products and/or intentionally oxidize the surface of the base materials.
• gases including gas mixtures containing CO, C0 2 , and/or fluorocarbons are utilized to remove hydrogen to enhance the mechanical strength of fabricated products.
• the present invention further contemplates the use of gases including gas mixtures to form nitride, carbide, boride, phosphide, silicide or other chemical layer on the surface of base materials, such as but not limited to metallic powders to enhance the wear resistance or corrosion resistance of the fabricated products.
• gases including gas mixtures to form nitride, carbide, boride, phosphide, silicide or other chemical layer on the surface of base materials, such as but not limited to metallic powders to enhance the wear resistance or corrosion resistance of the fabricated products.
• any combinations of these gases can be used to form binary, ternary, or higher order compounds such as nitride and boride at the same time.
• gases/fluids including their mixtures may be used to alter the alloy composition of the base material before, during and/or after additive manufacturing.
• Gases/fluids containing volatile organometallic components can be used to introduce or deposit metals by chemical vapor deposition, atomic layer deposition or other process on the surface of powders as they are used in the 3D printing process.
• reactive fluids including their mixtures would be ideally suited for use with stand alone laser cutting processes or in combination with the AM process.
• a fabricated object could be further shaped through the use of a laser which cuts by melting, burning or vaporizing the base material. After and/or during the cut the surface of the fabricated object would be exposed to the reactive fluid(s) and/or mixtures thereof so that the entire surface of the fabricated object will have the same desired chemistry.
• a technical effect of the invention is the ability to improve the mechanical properties such as higher wear resistance, higher corrosion resistance, higher mechanical strength, and lower residual stress of the metallic products fabricated by LAM.
• the mechanical and/or chemical properties of fabricated products rely on the chemical compositions and the grain structures of the matrix and surface of fabricated products as well as the base materials employed in the process.
• the existence of oxides or other impurities at the surface of the base materials prevents the adhesion of the base materials for fabricating products, which degrades the mechanical properties of fabricated products.
• the grain structure with more/larger pores and disorder of grains, derived from temperature gradient during the process, also causes the residual stress in fabricated products.
• FIG. 1 depicts a diagram of an additive manufacturing apparatus encompassing one aspect of the present invention wherein the reactive fluid(s) and base material are contacted with one another inside of the build chamber.
• FIG. 2 depicts a diagram of an additive manufacturing apparatus encompassing one aspect of the present invention wherein the reactive fluid(s) and base material are contacted with one another prior to entering the build chamber.
• FIG. 3 depicts a diagram of an additive manufacturing apparatus encompassing one aspect of the present invention wherein the reactive fluid(s) and base material are stored within the same container and have contacted one another prior to entering the build chamber.
• AM processes also, “additive manufacturing” processes
• AM processes refers to any process which results in a useful, three-dimensional object and includes a step of sequentially forming the shape of the object one layer at a time.
• AM processes include electron-beam melting (EBM), selective laser melting (SLM) or direct metal laser sintering (DMLS), direct metal laser melting (DMLM), selective laser sintering (SLS), fused deposition modeling (FDM), fused filament fabrication (FFF), or powder bed and inkjet head 3D printing (3DP) processes, laser-net-shape manufacturing, direct metal laser sintering (DMLS), plasma transferred arc, freeform fabrication, etc.
• EBM electron-beam melting
• SLM selective laser melting
• DMLS direct metal laser melting
• SLS selective laser sintering
• FDM fused deposition modeling
• FFF fused filament fabrication
• 3DP powder bed and inkjet head 3D printing
• a particular type of AM process uses an energy beam, for example, an electron beam or electromagnetic radiation such as a laser beam, to sinter or melt a powder material.
• AM processes often employ relatively expensive materials such as but not limited to, powders, metal powder materials, rods, liquids or wire as a raw material.
• the present invention relates generally to AM processes as a rapid way to manufacture an object (article, component, part, product, etc.) where a multiplicity of thin unit layers are sequentially formed to produce the object. More specifically, layers of a metallic powder are laid down and irradiated with an energy beam (e.g., laser beam) so that particles of the metallic powder within each layer are sequentially sintered (fused) or melted to solidify the layer or substrate.
• an energy beam e.g., laser beam
• one or more reactive fluids or fluid mixtures that react with the surface of the metallic powder or powders is brought into contact with the metallic powder prior to during and/or after the AM process to actively manipulate the surface chemistry of the powder material thus the chemical composition of the surface of the powder material is controlled/reformed/modified before, during and/or after the AM process.
• Fluids including gas mixtures containing hydrogen, carbon monoxide or other gas components that chemically reduce surface oxides and/or otherwise clean or remove impurities on the surface of solid powders are used instead of or in addition to pure purge gases (e.g. He, Ar or N 2 ) in the build chamber itself, as well as in the metallic-powder-delivery line, the metallic-powder-delivery container, or in the used-metallic-powder receiver.
• pure purge gases e.g. He, Ar or N 2
• the present invention includes bulk modification of a base material, for example a very thin film/layer (such as those less than 1 micron), it is feasible to modify the property of whole by exposing it to reactive fluids with energy assistance (such as thermal diffusion in semiconductor manufacturing).
• a base material for example a very thin film/layer (such as those less than 1 micron)
• energy assistance such as thermal diffusion in semiconductor manufacturing
• the present invention includes the treatment of a base material by a gas or gases including gas mixtures and could be employed to recycle used metallic powders, which leads to the cost reduction of powders.
• gases with higher thermal conductivity e.g. He
• the gases with higher thermal conductivity could be employed as a purge gas or a balance gas, which is effective to reduce the residual stress derived from temperature gradients.
• the present invention may further employ gases including gas mixtures to remove hydrogen in the powders or fabricated products and/or intentionally oxidize the surface of powders.
• gases including gas mixtures containing CO, C0 2 , and/or fluorocarbons are utilized to remove hydrogen to enhance the mechanical strength of fabricated products.
• oxygen, ozone, and/or hydrogen peroxide are utilized not only to remove hydrogen but also to form metal oxides materials.
• the present invention further contemplates the use of gases including gas mixtures to form nitride, carbide, boride, phosphide, silicide or other chemical layer on the surface of base materials to enhance the wear resistance or corrosion resistance of the fabricated products. Any combinations of these gases can be used to form binary, ternary, or higher order compounds such as nitride and boride at the same time. It is further contemplated that gases/fluids including their mixtures may be used to alter the alloy composition of the powder material before and/or during additive manufacturing. Gases/fluids containing volatile organometallic components can be used to introduce or deposit metals by chemical vapor deposition, atomic layer deposition or other process on the surface of powders as they are used in the 3D printing process.
• the AM apparatus comprises a build chamber within which an article can be fabricated, a movable build platform positioned within the build chamber and on which the article is fabricated, a base material/fluid delivery system, and an energy delivery system.
• the base material/fluid delivery system delivers a base material that has been chemically modified to the build platform.
• a heating system may be employed that is capable of heating the base material and the platform with a heated gas.
• the base material can be a metallic material, non-limiting examples of which include aluminum and its alloys, iron and its alloys, titanium and its alloys, nickel and its alloys, stainless steels, cobalt-chrome alloys, tantalum, and niobium.
• the reactive fluid is chosen based on the specific metallic material being used and the desired surface chemistry.
• Non-limiting examples of reactive fluid contemplated by this invention include highly diffusive gases and/or gas mixtures such as reducing, oxidizing reagent, reactive gases or reactive fluids.
• Fluids including gas mixtures containing hydrogen, carbon monoxide or other gas components that chemically reduce surface oxides and/or otherwise clean or remove impurities on the surface of the base materials are used instead of or in addition to pure purge gases (e.g. He, Ar or N 2 ) in the build chamber itself, as well as in the base material delivery line, the base material container, or in the used base material receiver.
• pure purge gases e.g. He, Ar or N 2
• Methods of producing a three-dimensional structure may include depositing a first layer of one or more of the aforementioned base materials on the platform thereby forming a substrate. At least one additional layer of base material is deposited and then the laser scanning steps for each successive layer are repeated thereby forming a thicker substrate until a desired object is obtained.
• the base material can be actively modified by changing the reactive gas during the layering process.
• the article is formed in layer-wise fashion until completion.
• the average grain size is, in an embodiment, about 10 to 100 ⁇ . Properties of metallic powders or metallic products are improved during product fabrication by spatio-temporally (chamber/line/container, continuously/cyclically/multiple-steps) controlled chemical reaction during the AM process.
• the present invention provides for a higher purity metal product that has an improvement of phase, crystal structure, and metallurgical structure of base materials in addition to a high dimensional accuracy and excellent microstructural characteristics, for example, characterized by the substantial absence of microstructural defects such as voids, impurities, inclusions, and particularly microcracks and porosity, without employing metal stamping, even though the product may be formed of a pure metal of choice and/or an alloy-based powder material that is considered to be resistant to sintering.
• the present invention provides a methodology for modification of the magnetic properties and residual stress in a fabricated product.
• the AM process according to the present invention may be carried out under an inert atmosphere wherein the base material has been stored in or reacted with the reactive fluid prior to entering the build chamber.
• the inert atmosphere is an atmosphere comprising a gas selected from the group consisting of helium, argon, hydrogen, oxygen, nitrogen, air, nitrous oxide, ammonia, carbon dioxide, and combinations thereof.
• the inert atmosphere is an atmosphere comprising a gas selected from the group consisting of nitrogen (N 2 ), argon (Ar), helium (He) and mixtures thereof.
• the inert atmosphere is substantially an argon gas atmosphere.
• AM process according to the present invention is carried out under an atmosphere of the desired reactive fluid wherein the base material has been stored in or reacted with the reactive fluid prior to entering the build chamber.
• the additive manufacturing (AM) device 10 includes a build chamber 100 having a movable build platform (not shown) upon which an object 90 is to be fabricated.
• the AM device 10 further includes an energy generating system 50 and a controller 40.
• a reactive fluid 60 or reactive fluids 60' and 60" is contacted with base material 70 as they are introduced into build chamber 100 of the AM device 10 to create an object 90 using energy generated by the generating system 50.
• base material 70 is contacted with reactive fluid 60 the surface of base material modified as desired resulting in modified base material 75 (not shown).
• the modification to the surface of base material 70 may be a chemical modification, a coating and/or the result of the adsorption of the reactive fluid 60.
• AM device is capable of introducing an inert gas 80 if necessary.
• Object 90 may take various forms. Controller 40 sends control signals 42 to generating system 50 and control signals 44 to build chamber 100 to control the heating and, in some embodiments, melting of modified base material 75 to form object 90. These control signals 42 and 44 may be generated using design data 30.
• Operator specified values can be computer fed into controlled to specify quantities and types of reactive gases that will contact base material 70 thus allowing for the operator to specifically design the chemical profile of each layer within object 90 during the actual fabrication process.
• Different profiles and repetition rates within the release of at least one reactive gas (60, 60' and/or 60") with respect to the course or progress of the layers being deposited can therefore be defined and varied.
• the reactive gas is contacted with the base material at differing times.
• reactive fluid 260 and base material 270 are contacted together in supply line 272 thereby providing more time for the chemical reaction to take place on the surface of base material 270.
• supply line 272 may run through an external energy source (not shown) prior to introduction into the build chamber.
• the modified base material (not shown) is then directed into build chamber 200 where object 290 is fabricated.
• FIG. 3 An alternate embodiment shown in Figure 3 is provided that not only has the benefit of modifying the surface chemistry of base material, but by storing and transporting the base material with reactive fluid 370 an enhanced safety, handling, delivery of some base material is achieved.
• reactive fluid 370 For example, low-oxygen containing powders or fine particles are explosive and by suspending them in the reactive fluid 370 the handling and safety of those materials is considerably increased.
• Table 1 below provide various example of reactive fluids and where that reaction in the AM process with the metallic material is to take place.
• alkylborane H 2 S
• alkyl sulfur PH 3
• the additive manufacturing device 10, shown in Figure 1 may be constructed by modifying currently available laser sintering or melting systems.
• the different embodiments may be achieved by replacing the inert gas typically found on these systems with reactive gas.
• the apparatus 10 is capable of processing a wide variety of materials, including but not limited to the following discussed below.
• the base material 70 may be pure aluminum or an aluminum alloy.
• the base material 70 also may be a mixture of particles of pure aluminum and one or more aluminum alloys or may be a mixture of various aluminum alloys. There are no restrictions on the composition of an aluminum base material 70 other than it is to contain sufficient aluminum in metallic form for the powder material particles to form a substantially enveloping film of alumina.
• Base material 70 may further be nickel and nickel alloys including nickel-based superalloys; copper and its alloys; refractory metals, including noble metals and metalloids and/or materials having a high oxidation potential, for example, copper, iron, titanium, ruthenium, cadmium, zinc, rhodium, potassium, sodium, nickel, bismuth, tin, barium, germanium, lithium, strontium, magnesium, beryllium, lead, calcium, molybdenum, tungsten, cobalt, indium, silicon, gallium, iron, zirconium, chromium, boron, manganese, aluminum, lanthanum, neodymium, niobium, vanadium, yttrium, and/or scandium.
• nickel and nickel alloys including nickel-based superalloys; copper and its alloys; refractory metals, including noble metals and metalloids and/or materials having a high oxidation potential, for example, copper, iron
• Base material 70 may further be metallic glasses or amorphous metallic compounds; ternary, quaternary, or higher-order metallic alloys having amorphous structures, for example, aluminum-titanium-based alloy such as Ti-Al-Fe and Ti-Al-N, zirconium-based alloy such as Zr-Cu-Al-Ni, palladium-based alloy such as Pd-Ni-P, iron- based alloy comprising the combination of iron, boron, silicon, carbon, phosphorous, nickel, cobalt, chromium, nitrogen, titanium, zirconium, vanadium, and niobium.
• ternary, quaternary, or higher-order metallic alloys having amorphous structures for example, aluminum-titanium-based alloy such as Ti-Al-Fe and Ti-Al-N, zirconium-based alloy such as Zr-Cu-Al-Ni, palladium-based alloy such as Pd-Ni-P, iron- based alloy compris
• boron, phosphorous, silicon, carbon, and/or any other element can be added within the apparatus 10 using reactive fluids like diborane, phosphine, and methane.
• the present invention could be applied for formation of amorphous metallic oxides, for example, In-Ga-Zn-0 and Zn-Rh-O. Oxides could be formed within the apparatus 10 using reactive fluids like oxygen or hydrogen peroxide.
• the present invention could select various reactive fluids, for example,
• reducing agents hydrogen, carbon monoxide, formic acid, ammonia, hydrazine, monom ethyl hydrazine, 1,2-dimethyl hydrazine;
• saturated hydrocarbons such as methane, ethane, propane, butane, pentane, hexane, heptane, and higher hydrocarbons, unsaturated hydrocarbons such as acetylene, propylene, isomers of butene, ethylene;
• oxidizing agent carbon dioxide, oxygen, carbon tetrafluoride, fluoroform, methylene difluoride, fluoromethane, hydrogen peroxide, ozone, nitrous oxide, nitric oxide, nitrogen dioxide, nitrogen trifluoride, fluorine;
• nitriding agent monomethylamine, dimethylamine, trimethylamine, ammonia, hydrazine, monom ethyl hydrazine, 1,2-dimethyl hydrazine;
• bonding agent diborane, trimethyl borane, tetram ethyl diborane, trichloroborane, trifluoroborane;
• sulfiding agent hydrogen sulfide, methanethiol, ethanethiol, propanethiol, butanethiol, pentanethiol, dialkylsulfides;
• phosphiding agent phosphine, tert-butylphosphine, triethylphosphine, trimethylphosphine, phosphorous oxy chloride, trifluorophosphine, trichlorophosphine:
• silanizing agent monosilane, disilane, higher silanes, alkyl silanes, tetraethoxysilane, fluorosilanes, chlorosilanes, aminosilanes;
• (9) seleniding agent hydrogen selenide, alkyl selenides

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