Method for manufacturing copper alloy powder for metallic AM

Abstract

The method for manufacturing copper alloy powder for AM metal includes: a casting step in which a copper alloy ingot is manufactured by a casting apparatus comprising: a copper molten metal supply unit for melting copper raw material composed of high-purity copper with a purity of 99.99% by mass or more to obtain copper molten metal; an addition unit for adding alloying elements of a copper alloy to the copper molten metal under a non-oxidizing atmosphere to obtain copper alloy molten metal; and a mold to which the copper alloy molten metal is supplied; and an atomization treatment step in which the copper alloy ingot is used as raw material and is atomized and melted in an inactive gas or vacuum atmosphere to obtain powder, wherein the O concentration in the copper alloy ingot is less than 10 ppm by mass and the H concentration is less than 5 ppm by mass.

Description

Technical Field

[0001] This invention relates to a method for manufacturing copper alloy powder for metal AM technology, which is most suitable for metal additive manufacturing (metal AM) technology.

[0002] This application claims priority based on Japanese Patent Application No. 2022-169920, filed on October 24, 2022, the contents of which are incorporated herein by reference. Background Technology

[0003] In recent years, metal AM (metal 3D printing) technology, which primarily uses powder as a raw material and shapes products using metal 3D printers, has been put into practical use as a method for manufacturing metal components with various three-dimensional shapes. Examples of major metal AM technologies that utilize metal powder include powder bed fusion (PBF) using electron beams or laser beams, and binder jetting.

[0004] Copper alloys possess a variety of fundamental properties suitable for industrial applications, including electrical conductivity, thermal conductivity, mechanical properties, wear resistance, and heat resistance, making them suitable as raw materials for various components. Therefore, in recent years, the use of metal AM (metal alloy powder) to form components of various shapes has been piloted in various fields such as aerospace and electrical component applications, and the demand for copper and copper alloy components manufactured using metal AM is increasing.

[0005] For example, patent documents 1 and 2 propose techniques for using copper alloy powder to create laminated shapes based on metal AM.

[0006] Patent Document 1: Japanese Patent Application Publication No. 2016-211062

[0007] Patent Document 2: Japanese Patent Application Publication No. 2019-070169

[0008] Non-patent document 1: YMArisoy et.al., "Influence of scan strategy and process parameters on microstructure and its optimization in additively manufactured nickel alloy 625via laser powder bed fusion", The International Journal of Advanced Manufacturing Technology, Volume 90, pp1393-1417 (2017).

[0009] Metal structures created by metal AM (Ammonium Metallization) are used as structural components for various purposes. Therefore, when there are pores in the stacked structures or when the microstructure of the metal material is uneven, problems arise in terms of thermomechanical and electrical reliability.

[0010] Currently, the most commonly used shaping method in metal AM is laser PBF, and shaping based on laser PBF has also been tried in copper and copper alloys.

[0011] However, in the process of creating laminated shapes by irradiating with laser or electron beams, a thin powder layer (powder bed) is first formed. Then, the powder bed is locally irradiated with a laser or electron beam to melt and solidify the material. However, for copper and copper alloys, due to copper's higher reflectivity to visible and infrared light compared to other metals such as iron, titanium, and nickel, the melting behavior of copper alloy powder becomes unstable during laser PBF (Powder Bed Fabrication). This easily leads to porosity within the laminated shape, resulting in inconsistent quality and poor productivity in the products manufactured by laser PBF. Therefore, improvements in the quality and productivity of copper and copper alloys manufactured by laser PBF are required.

[0012] Currently, the most widely used form of raw material for metal AM (Advanced Metal Assembly) is powder. For example, in metal AM using laser PBF (Pulse Bed Fabrication), the absorption characteristics of electromagnetic waves by particles caused by the coupling / interaction between the surface layer of each particle constituting the raw material powder and electromagnetic waves affect the melting behavior of the raw material powder and have a significant impact on the quality, including the productivity and defect density of the components. For example, in metal AM processes using powder beds, the thickness of the powder bed formed in a single stacking process is, for example, about tens of micrometers (Non-Patent Literature 1). By irradiating this relatively thin powder bed with converging electromagnetic waves, the raw material powder is melted, and this process of stacking and solidification is repeated multiple times to achieve the desired shape structure. The absorption characteristics of solids to electromagnetic waves have a significant impact on the basic process of this stacking modeling using powder beds. For example, the absorption characteristics of solids to electromagnetic waves are affected by the material composition. Therefore, improving the uniformity of the material composition or microstructure of the powder becomes extremely important for achieving stable quality and high productivity in the overall stacked model.

[0013] Furthermore, for copper alloys, past research and development have yielded materials that maintain high electrical conductivity while achieving high mechanical strength, as well as materials with excellent heat resistance. Similarly, for metallic AM (alloy-grade metal), there is a societal demand for metallic AM components with desired shapes using existing high-performance copper alloy compositions. However, when a powder bed of such known copper alloy compositions is irradiated with a laser or electron beam for lamination molding, and when the reproducibility of the microstructure related to the raw material powder, including the reproducibility of the composition of powder particles in various parts of the irradiated laser beam, is lacking, the melting behavior of the powder becomes uneven. As a result, structural defects such as pores may be induced within the molded body, or mechanical properties may deteriorate due to the inhomogeneity of the metal composition of the molded body.

[0014] The reproducibility of the fine structure of this raw material powder, including the reproducibility of the powder's material composition, presents the same problem in other metal AM processes such as binder spraying, especially in copper alloy lamination molding. Due to these various raw material issues, improving productivity is a significant challenge. Existing copper alloy powders used in metal AM processes lack sufficient material properties suitable for the process, resulting in defects easily arising in molded objects manufactured through various lamination molding processes, thus failing to achieve adequate productivity.

[0015] Furthermore, one of the factors contributing to structural defects in metal AM (Ampere Atom) molded objects is the formation of porosity due to the entrapment of gases. When using existing copper alloy powder for lamination molding via the PBF (Plain Fiber) method, gases are generated during powder melting due to impurities contained within the copper alloy powder. The molten or solidified copper alloy traps these gas components, sometimes creating porosity within the resulting lamination, potentially preventing the production of stable and high-quality laminations. Summary of the Invention

[0016] The present invention was made in view of the foregoing circumstances, and its object is to provide a method for manufacturing copper alloy powder for metal AM, wherein the copper alloy powder for metal AM can stably manufacture high-quality laminated models with high reproducibility of the microstructure of the laminated model made by metal AM and few structural defects such as pores.

[0017] To address this issue, the inventors conducted in-depth research and discovered that by using powder manufactured through an atomization process, the generation of internal pores in the manufactured laminated shapes can be significantly suppressed. This atomization process involves using a high-purity copper alloy ingot with sufficiently reduced O and H concentrations as raw material, and then melting and decomposing it through atomization in an inactive gas or vacuum atmosphere, thereby pulverizing it.

[0018] Regarding porosity suppression in laser PBF (Powder-Based Fabrication) technology, it can be considered that by increasing the purity of the copper alloy powder used as raw material, the reproducibility of the overall material composition of the powder is improved. That is, the reproducibility of the powder composition in each part of the powder bed irradiated by the laser is improved. As a result, the reproducibility of the melting / solidification behavior of the raw material powder caused by laser irradiation is improved and stabilized. Moreover, the detached gas components such as H2O that may be generated due to O and H in the laser raw material powder are suppressed. Through such effects, the generation of porosity in the laminated model can be suppressed.

[0019] This invention was made based on the above-mentioned understanding. The method for manufacturing copper alloy powder for metallic AM according to aspect 1 of this invention is characterized by comprising: a casting step in which a copper alloy ingot is manufactured by a casting apparatus, the casting apparatus comprising: a copper molten metal supply unit for melting copper raw materials composed of high-purity copper with a purity of 99.99% by mass or more to obtain copper molten metal; an addition unit for adding alloying elements of a copper alloy to the copper molten metal under a non-oxidizing atmosphere to obtain copper alloy molten metal; and a mold supplied with the copper alloy molten metal; and an atomization treatment step in which the copper alloy ingot is used as raw material and is atomized and melted in an inactive gas or vacuum atmosphere, thereby being powdered, wherein the O concentration in the copper alloy ingot is 10 ppm by mass or less, and the H concentration is 5 ppm by mass or less.

[0020] According to aspect 1 of the present invention, the method for manufacturing copper alloy powder for metallic AM is such that since the O concentration in the copper alloy ingot is less than 10 ppm by mass and the H concentration is less than 5 ppm by mass, copper alloy powder for metallic AM can be manufactured by using the copper alloy ingot as raw material. This copper alloy powder for metallic AM can stably manufacture high-quality laminated molded objects with high reproducibility of microstructures and few structural defects such as pores.

[0021] Regarding aspect 2 of the present invention, in the method for manufacturing copper alloy powder for metallic AM in aspect 1, it is preferable that the S concentration in the copper alloy ingot is 15 ppm by mass or less.

[0022] According to aspect 2 of the present invention, the method for manufacturing copper alloy powder for metallic AM is such that since the S concentration in the copper alloy ingot is less than 15 ppm by mass, the component that is easily contained in copper, namely S, can be sufficiently reduced. By using the copper alloy ingot as raw material to manufacture copper alloy powder, copper alloy powder for metallic AM can be manufactured. This copper alloy powder for metallic AM can stably manufacture higher quality laminated molded objects with high reproducibility of microstructure and fewer structural defects such as pores.

[0023] Regarding aspect 3 of the present invention, in the method for manufacturing copper alloy powder for metallic AM in aspect 1 or aspect 2, it is preferable that the total concentration of O, H and S in the copper alloy ingot is 30 ppm by mass or less.

[0024] According to aspect 3 of the present invention, in the method for manufacturing copper alloy powder for metallic AM, since the total concentration of O, H and S in the copper alloy ingot is less than 30 ppm by mass, copper alloy powder for metallic AM can be manufactured by using the copper alloy ingot as raw material. This copper alloy powder for metallic AM can stably manufacture higher quality laminated molded objects with high reproducibility of microstructures and fewer structural defects such as pores.

[0025] Regarding aspect 4 of the present invention, in the method for manufacturing copper alloy powder for metallic AM in any of aspects 1 to 3, it is preferable that the total content of the alloying elements in the copper alloy ingot is in the range of 0.01% by mass or more and 50% by mass or less.

[0026] According to aspect 4 of the present invention, the method for manufacturing copper alloy powder for metallic AM is able to stably manufacture copper alloy powder for metallic AM with uniform alloy element content because the total content of the alloying elements in the copper alloy ingot is in the range of 0.01% by mass or more and 50% by mass or less.

[0027] Furthermore, due to the presence of alloying elements, it is possible to manufacture copper alloy powders for AM metals with excellent electrical conductivity, thermal conductivity, and other properties.

[0028] Regarding aspect 5 of the present invention, in the method for manufacturing copper alloy powder for metallic AM according to any one of aspects 1 to 4, it is preferable to contain one or more alloying elements selected from Cr, Zr, Si, Ni, Mg, Ti, Al, Zn, Ca, Sn, Pb, Fe, Mn, Te, Nb, Co, Sb, Bi, Ag, Ta, W, Mo and P.

[0029] According to aspect 5 of the present invention, the method for manufacturing copper alloy powder for metallic AM can produce copper alloy powder for metallic AM with excellent electrical conductivity, thermal conductivity and other properties because it contains any one or more of the above-mentioned alloying elements.

[0030] Regarding aspect 6 of the present invention, in the method for manufacturing copper alloy powder for metallic AM in any of aspects 1 to 5, it is preferable that the copper alloy ingot is continuously manufactured by a continuous casting apparatus in the casting process.

[0031] According to aspect 6 of the present invention, the method for manufacturing copper alloy powder for metallic AM has excellent production efficiency because copper alloy ingots are continuously manufactured by a continuous casting apparatus. Furthermore, the method for manufacturing copper alloy powder for metallic AM according to aspect 6 of the present invention enables the continuous casting of copper alloy ingots with stable alloy element content, thereby enabling the stable manufacture of copper alloy powder for metallic AM with uniform alloy element content.

[0032] According to the present invention, a method for manufacturing copper alloy powder for metal AM is provided, wherein the copper alloy powder for metal AM can stably manufacture high-quality laminated models with high reproducibility of the microstructure and few structural defects such as pores in the laminated models made by metal AM. Attached Figure Description

[0033] Figure 1 This is a flowchart of the method for manufacturing copper alloy powder for metallic AM according to this embodiment.

[0034] Figure 2 This is a flowchart of the melting / casting process in the manufacturing method of copper alloy powder for metal AM according to this embodiment.

[0035] Figure 3 This is a flowchart of the copper alloy raw material preparation process in the method for manufacturing copper alloy powder for metal AM according to this embodiment.

[0036] Figure 4 This is a flowchart of the atomization process in the manufacturing method of copper alloy powder for metal AM according to this embodiment.

[0037] Figure 5 This is a schematic diagram illustrating the continuous casting apparatus used in the manufacturing method of copper alloy powder for metallic AM in this embodiment.

[0038] Figure 6 This is a schematic diagram illustrating other continuous casting apparatus used in the method for manufacturing copper alloy powder for metallic AM in this embodiment. Detailed Implementation

[0039] Hereinafter, with reference to the accompanying drawings, a method for manufacturing copper alloy powder for metal AM according to an embodiment of the present invention will be described.

[0040] This embodiment describes a method for manufacturing copper alloy powder for metallic AM (acoustic alloying). Furthermore, in this embodiment, copper alloy powder suitable for the laser PBF (photolithography-based powder exchange) method is manufactured.

[0041] Regarding the method for manufacturing copper alloy powder for metallic AM according to this embodiment, using Figure 1 The flowchart is used for illustration.

[0042] The method for manufacturing copper alloy powder for metal AM according to this embodiment includes: a melting / casting process S01 for obtaining a copper alloy ingot; a copper alloy raw material manufacturing process S02 for processing the obtained copper alloy ingot into wire rods and using them as copper alloy raw materials; and a powder processing process S03 for processing the copper alloy raw materials into powder.

[0043] (Melting / Casting Process S01)

[0044] First, a copper alloy ingot 1 with a specified composition is manufactured. In the melting / casting process S01, as follows... Figure 2 As shown in the flowchart, it has a melting process S11, an alloy element addition process S12, and a continuous casting process S13.

[0045] Then, in this embodiment, using Figure 5 The continuous casting apparatus 10 shown produces a copper alloy ingot 1.

[0046] The continuous casting apparatus 10 includes: a melting furnace 11; a tundish 12 disposed downstream of the melting furnace 11; a connecting tank 13 connecting the melting furnace 11 and the tundish 12; an adding unit 14 for adding alloying elements to the tundish 12; a continuous casting mold 15 disposed downstream of the tundish 12; and a pouring nozzle 16 for injecting molten copper alloy from the tundish 12 into the continuous casting mold 15.

[0047] In the melting furnace 11 of the copper molten liquid supply section, copper raw materials are melted in a non-oxidizing atmosphere (inactive gas atmosphere or reducing atmosphere) to obtain copper molten liquid 3 (melting process S11).

[0048] Here, the copper raw material melted in the melting furnace 11 is high-purity copper with a purity of 99.99% by mass or higher (e.g., high-purity electrolytic copper or oxygen-free copper). Furthermore, the copper raw material melted is high-purity copper of grade 4N (99.99% by mass) or higher, but more preferably high-purity copper of grade 5N (99.999% by mass) or higher, and even more preferably high-purity copper of grade 6N (99.9999% by mass) or higher. Moreover, the resulting copper melt 3 is preferably oxygen-free copper melt.

[0049] In the connecting tank 13, the obtained molten copper 3 is supplied to the tundish 12 in a non-oxidizing atmosphere (inactive gas atmosphere or reducing atmosphere). The connecting tank 13 is disposed between the melting furnace 11 and the tundish 12, and the molten copper 3 passes through the connecting tank 13 in a non-oxidizing atmosphere.

[0050] Furthermore, the copper molten liquid 3 is maintained in the intermediate ladle 12 under a non-oxidizing atmosphere (inactive gas atmosphere or reducing gas atmosphere).

[0051] In addition, since the melting furnace 11, connecting tank 13, and tundish 12 are set in a non-oxidizing atmosphere (inactive gas atmosphere or reducing atmosphere), the gas components (O, H) in the copper melt 3 will be reduced.

[0052] Furthermore, in the intermediate ladle 12, alloying elements are added to the copper melt 3 using the addition section 14 (alloying element addition process S12).

[0053] By adding alloying elements to copper melt 3 with significantly reduced gas composition (O, H), the yield of alloying element addition is good, thus reducing the amount of alloying elements used and reducing the manufacturing cost of copper alloys.

[0054] Furthermore, by adding alloying elements to the copper melt 3 flowing in the tundish 12, the alloying elements can be uniformly dissolved, thereby enabling the continuous production of copper alloy melt with stable composition values.

[0055] The obtained copper alloy molten liquid is injected into the continuous casting mold 15 through the pouring nozzle 16 to continuously manufacture copper alloy ingot 1 (continuous casting process S13).

[0056] In this embodiment, the O concentration in the obtained copper alloy ingot 1 is 10 ppm by mass or less, and the H concentration is 5 ppm by mass or less.

[0057] The O concentration is more preferably 8 ppm by mass or less, and the lower limit is not particularly limited, but may be a value excluding 0 (or a value exceeding 0), or may be 0.5 ppm by mass. The H concentration is more preferably 3 ppm by mass or less, and the lower limit is not particularly limited, but may be a value excluding 0 (or a value exceeding 0), or may be 0.2 ppm by mass.

[0058] Furthermore, in the obtained copper alloy ingot 1, the S concentration is preferably 15 ppm by mass or less. The S concentration is more preferably 11 ppm by mass or less. The lower limit is not particularly limited and can be a value excluding 0 (or a value exceeding 0) or 0.01 ppm by mass.

[0059] Furthermore, in the obtained copper alloy ingot 1, the total content of impurity elements (excluding O, H, and S) other than Cu and alloying elements is preferably 0.04% by mass or less.

[0060] Furthermore, in the obtained copper alloy ingot 1, the total concentration of O, H, and S is preferably 30 ppm by mass or less. More preferably, the total concentration of O, H, and S is 25 ppm by mass or less, even more preferably 22 ppm by mass or less, and may also be 20 ppm by mass or less. The lower limit of the total concentration of O, H, and S is not particularly limited; it may be a value excluding 0 (or a value exceeding 0), or it may be 0.71 ppm by mass.

[0061] (Copper alloy raw material manufacturing process S02)

[0062] Next, the copper alloy ingot 1 obtained in the melting / casting process S01 is processed into wire rods to manufacture copper alloy raw materials.

[0063] In the copper alloy raw material manufacturing process S02, such as Figure 3 As shown, it includes an extrusion process S21, a drawing process S22, and a cutting process S23.

[0064] In the extrusion process S21, a copper alloy ingot with a circular cross-section is heated and processed into a bar of a specified diameter through hot extrusion.

[0065] In addition, in this embodiment, it is preferable to set the heating temperature during hot extrusion processing in the range of 700°C or higher and 1000°C or lower.

[0066] In the drawing process S22, the bar obtained by the extrusion process S21 is drawn to form a wire of a specified diameter.

[0067] In addition, there are no particular restrictions on the temperature of the drawing process, but it is preferred to be in the range of -200°C to 200°C, which is the temperature at which cold rolling or hot rolling is performed, and especially preferred to be room temperature.

[0068] In the cutting process S23, the wire obtained by the drawing process S22 is cut into a specified length and set as a copper alloy raw material.

[0069] Here, the O concentration in the obtained copper alloy raw material is preferably less than 10 ppm by mass, and the H concentration is preferably less than 5 ppm by mass.

[0070] Furthermore, the sulfur concentration in the obtained copper alloy raw material is preferably below 15 ppm by mass.

[0071] Furthermore, the total content of impurity elements (excluding O, H, and S) in the obtained copper alloy raw material is preferably less than 0.04% by mass.

[0072] (Powder processing step S03)

[0073] Next, copper alloy raw materials obtained in the copper alloy raw material manufacturing process S02 are atomized to produce copper alloy powder for metal AM.

[0074] In the powder processing step S03, such as Figure 4 As shown, it includes a melting process S31, an atomization process S32, and a grading process S33.

[0075] In the melting process S31, the copper alloy raw material is heated and melted to obtain molten metal. Here, in this embodiment, the atmosphere during melting is preferably a non-oxidizing atmosphere.

[0076] In the atomization process S32, the molten metal obtained in the melting process S31 is rapidly cooled by spraying it with a high-pressure gas, thereby producing spherical or spherical-like powder. Inert gases such as argon and nitrogen can be used as the gas for gas atomization. The melting temperature of the copper alloy raw material in the gas atomization process (the melting temperature during gas atomization) is preferably above the melting point of copper and below 1500°C. The melting temperature during gas atomization can be above 1085°C and below 1500°C.

[0077] In the grading process S33, the obtained powder is graded to obtain copper alloy powder with a specified particle size distribution.

[0078] The copper alloy powder for metal AM is manufactured through the above processes.

[0079] The copper alloy powder for metal AM produced by the manufacturing method of the present embodiment contains various alloying elements as described above.

[0080] In this embodiment, the alloying element refers to an element intentionally added during the manufacturing method of the copper alloy powder for metallic AM according to this embodiment. In this embodiment, sometimes a portion of the alloying element is referred to as an active metal element.

[0081] In the copper alloy ingot of this embodiment, it is preferable to contain one or more alloying elements selected from Cr, Zr, Si, and Ni.

[0082] The alloying elements are not limited to the above-mentioned components, but preferably include one or more of the following as alloying elements: Cr, Zr, Si, Ni, Mg, Ti, Al, Zn, Ca, Sn, Pb, Fe, Mn, Te, Nb, Co, Sb, Bi, Ag, Ta, W, Mo and P.

[0083] Furthermore, in the copper alloy ingot of this embodiment, it is preferable to contain one or more active metal elements as alloying elements.

[0084] Examples of active metallic elements include Cr, Zr, Si, Ni, Mg, Ti, Ni, Al, Zn, Ca, Sn, Pb, Fe, Mn, Te, and Nb.

[0085] Furthermore, in the copper alloy ingot of this embodiment, the total content of alloying elements is preferably in the range of 0.01% by mass or more and 50% by mass or less. More preferably, the total content of alloying elements is 0.02% by mass or more and 45% by mass or less, and may also be 5% by mass or less.

[0086] In addition, copper alloy powder for metal AM can contain impurity elements other than alloying elements (excluding O, H, S and N) within a range that does not affect the properties.

[0087] Impurity elements (excluding O, H, S, and N) refer to contaminants originating from the manufacturing process or trace impurities present in the raw materials, rather than intentionally introduced components. In this embodiment, impurity elements may be unavoidable impurities.

[0088] Here, the total amount of impurity elements (excluding O, H, S and N) in the copper alloy powder for metal AM can be less than 0.07% by mass, less than 0.06% by mass, less than 0.05% by mass, preferably 0.04% by mass, more preferably 0.03% by mass, more preferably 0.02% by mass, and even more preferably 0.01% by mass.

[0089] Furthermore, in processes performed under limited pressure, such as atomization, atmospheric components may be present in the powder due to atmospheric components in the atmosphere or the process itself. For example, nitrogen, as an atmospheric component, may be present in the powder. In the copper alloy powder for metal AM in this embodiment, the nitrogen concentration (N concentration) is preferably 30 ppm by mass, more preferably 20 ppm by mass, and even more preferably 10 ppm by mass or less. Furthermore, in the copper alloy powder for metal AM in this embodiment, it is even more preferable that the nitrogen concentration (N concentration) is 5 ppm by mass or less. The lower limit of the N concentration is not particularly limited and can be a value excluding 0 (or a value exceeding 0).

[0090] In addition, the numerical precision error in the composition of the copper alloy particles constituting the copper alloy powder for metallic AM is ±10% (excluding O, H, S and N).

[0091] Furthermore, the copper alloy powder for metallic AM produced by the manufacturing method of this embodiment contains one or more alloying elements selected from Cr, Zr, Si, and Ni. The total content of the alloying elements can be in the range of 0.01% by mass or more and 50% by mass or less, more preferably in the range of 0.01% by mass or more and 10% by mass or less, more preferably in the range of 0.01% by mass or more and 5% by mass or less, and may also be 0.02% by mass or more. Moreover, the alloying elements in the copper alloy powder for metallic AM produced by this embodiment are not limited to the above-mentioned components. Examples of alloying elements (active metal elements) include one or more selected from Cr, Zr, Si, Ni, Mg, Ti, Al, Zn, Ca, Sn, Pb, Fe, Mn, Te, Nb, Co, Sb, Bi, and Ag. Furthermore, the O concentration in the copper raw material composed of oxygen-free copper is less than 10 ppm by mass and the H concentration is less than 5 ppm by mass. Therefore, the O concentration and H concentration of the copper alloy powder for metal AM produced by the manufacturing method of the present embodiment are low.

[0092] According to the manufacturing method of the copper alloy powder for metal AM in this embodiment as described above, the O concentration in the copper alloy ingot obtained in the melting / casting process S01 is less than 10 ppm by mass and the H concentration is less than 5 ppm by mass. Therefore, by using the copper alloy ingot as raw material to manufacture copper alloy powder, it is possible to manufacture copper alloy powder for metal AM. This copper alloy powder for metal AM can stably manufacture high-quality laminated molded objects with high reproducibility of microstructure and few structural defects such as pores.

[0093] In the method for manufacturing copper alloy powder for metal AM in this embodiment, when the S concentration in the copper alloy ingot is 15 ppm by mass or less, the component that is easily included in copper, namely S, can be sufficiently reduced. By using the copper alloy ingot as raw material to manufacture copper alloy powder, copper alloy powder for metal AM can be manufactured. This copper alloy powder for metal AM can stably manufacture higher quality laminated molded objects with high reproducibility of microstructure and fewer structural defects such as pores.

[0094] In the manufacturing method of copper alloy powder for metal AM in this embodiment, when the total content of impurity elements (excluding Cu and alloying elements, such as O, H and S) in the copper alloy ingot is 0.04% by mass or less, the amount of impurity elements is sufficiently reduced. By using the copper alloy ingot as raw material to manufacture copper alloy powder, copper alloy powder for metal AM can be manufactured. This copper alloy powder for metal AM can stably manufacture higher quality laminated molded objects with high reproducibility of microstructure and fewer structural defects such as pores.

[0095] In the manufacturing method of copper alloy powder for metal AM according to this embodiment, when alloying elements are included, it is possible to manufacture copper alloy powder for metal AM that achieves various excellent properties such as electrical conductivity and thermal conductivity.

[0096] Furthermore, the continuous casting apparatus 10 can obtain copper alloy ingots with stable alloy element content, and can stably manufacture copper alloy powder for AM metal with uniform alloy element content. It can be considered that this uniform alloy element content in the copper alloy powder for AM metal, for example in PBF molding processes using electron beams or laser beams, achieves uniform energy absorption throughout the powder bed, resulting in highly reproducible and reliable stacked molded objects.

[0097] In the method for manufacturing copper alloy powder for metal AM in this embodiment, copper alloy ingot 1 can be manufactured efficiently when copper alloy ingots are continuously manufactured by the continuous casting apparatus 10.

[0098] The manufacturing method of copper alloy powder for metal AM according to the embodiments of the present invention has been described above. However, the present invention is not limited thereto, and appropriate modifications can be made without departing from the technical concept of the invention.

[0099] For example, in the above embodiments, the method of manufacturing powder by gas atomization has been described, but it is not limited to this. Copper alloy powder can also be manufactured by water atomization, centrifugal atomization, inductively coupled plasma, or plasma atomization.

[0100] Furthermore, the metal AM obtained as described above can be subjected to appropriate heat treatment to achieve microstructure stabilization. During this heat treatment, a suitable atmosphere such as an inert gas or a vacuum can be selected.

[0101] Furthermore, in this embodiment, a method for manufacturing copper alloy powder for metal AM suitable for the PBF method using laser has been described, but it is not limited to this, and copper alloy powder for metal AM applicable to other metal AM methods may also be used.

[0102] Furthermore, in this embodiment, the use of Figure 5 The method of manufacturing copper alloy ingots using the continuous casting apparatus shown has been described, but it is not limited to this and other casting apparatuses may also be used.

[0103] For example, you can use Figure 6The continuous casting apparatus 101 shown includes: an oxygen-free copper supply mechanism (molten copper supply section) 102 located at the upstream end; a heating furnace 103 located downstream of it; an tundish 104 located downstream of the heating furnace 103 and supplying molten copper; molten copper supply channels 105a, 105b, and 105c connecting the oxygen-free copper supply mechanism 102 to the heating furnace 103; a tank 106 connecting the heating furnace 103 and the tundish 104; an addition mechanism (addition section) 107 and 108 for adding alloying elements in a non-oxidizing atmosphere; and a continuous casting mold 142. Furthermore, the interiors of the oxygen-free copper supply mechanism 102, the heating furnace 103, the tundish 104, the molten copper supply channels 105a, 105b, and 105c, and the tank 106 are each provided with a non-oxidizing atmosphere.

[0104] The oxygen-free copper supply mechanism 102 consists of a melting furnace 121 for melting copper raw materials, a holding furnace 122 for temporarily holding the molten copper obtained by melting in the melting furnace 121, a degassing treatment device 124 for removing oxygen and hydrogen from the molten copper, and molten liquid supply channels 105a, 105b, and 105c connected to them.

[0105] The degassing treatment apparatus 124 has a gas bubbling device as a stirring mechanism to stir the molten copper inside it, for example by performing bubbling based on inactive gases to remove oxygen and hydrogen from the molten copper.

[0106] To prevent the molten copper and oxygen-free copper melt from being oxidized, the interior of the melt supply channels 105a, 105b, and 105c is set with a non-oxidizing atmosphere. This non-oxidizing atmosphere is formed, for example, by blowing a mixture of nitrogen and carbon monoxide, or an inert gas such as argon, into the melt supply channels.

[0107] The alloying mechanism includes a first addition mechanism 107 disposed in the heating furnace 103 and a second addition mechanism 108 disposed in the tundish 104.

[0108] If alloying elements are continuously or intermittently added from the first adding mechanism 107 provided in the heating furnace 103, the alloying elements are added to the oxygen-free copper molten liquid stored in the heating furnace 103. Here, the oxygen-free copper molten liquid stored in the storage section is heated by a high-frequency induction coil, which promotes the melting of the added alloying elements.

[0109] Furthermore, if alloying elements are continuously or intermittently added from the second adding mechanism 108 provided in the tundish 104, the alloying elements are added to the oxygen-free copper molten liquid flowing through the tundish 104. Here, the oxygen-free copper molten liquid flowing through the tundish 104 is heated to a high temperature in the heating furnace 103 and flows within the tundish 104, thus promoting the melting of the added alloying elements.

[0110] Example

[0111] To verify the effectiveness of the present invention, the following confirmation experiment was conducted.

[0112] (Example of the invention)

[0113] First, using the manufacturing method described in the embodiments, C18000 ingots with the composition shown in Table 1 are produced using copper raw materials composed of high-purity copper of grade 4N.

[0114] The impurities shown in Table 1 are impurity elements (excluding O, H and S).

[0115] Next, using the prepared C18000 ingot as raw material, copper alloy powder for metallic AM with the composition shown in Table 2 was produced by argon gas atomization, and then sieved into a particle size suitable for the powder bed of metallic AM. The gas atomization process was carried out at a melting temperature of 1300°C.

[0116] Regarding the copper alloy powder for metal AM of the present invention, the particle size distribution was measured using MT3300EXII manufactured by MICRO TRACK CO.,LTD., and the results showed a particle size distribution based on volume: 10% cumulative particle size of 16 μm, 50% cumulative particle size of 28 μm, and 90% cumulative particle size of 45 μm.

[0117] Then, using the copper alloy powder for metal AM according to the present invention, and using a commercially available laser PBF device, at an energy density of 13 J / mm², 2 Small pieces of layered shapes are created under certain conditions.

[0118] (Existing example)

[0119] As an example, commercially available metal AM C18000 powder as shown in Table 2 was prepared.

[0120] Regarding the existing example of metal AM C18000 powder, the particle size distribution was measured using MICRO TRACK CO.,LTD. MT3300EXII, and the results were obtained as a volume-based particle size distribution with a 10% cumulative particle size of 13 μm, a 50% cumulative particle size of 33 μm, and a 90% cumulative particle size of 57 μm.

[0121] Then, using existing metal AM C18000 powder and a commercially available laser PBF device, small pieces of the stacked model were produced under the same modeling conditions as the present invention, including the same layer thickness.

[0122] (Composition of copper alloy powder for casting ingots and metal AM)

[0123] The concentrations of O in the ingots shown in Table 1, the copper alloy powder for metallic AM in this invention, and the copper alloy powder for metallic AM in conventional examples were determined using the inert gas melting-infrared absorption method; the concentrations of H were determined using the inert gas melting-thermal conductivity method; and the concentrations of S were determined using the combustion-infrared absorption method. Furthermore, the concentrations of components other than copper were determined using a combination of fluorescence X-ray diffraction analysis, glow discharge mass spectrometry, and inductively coupled plasma mass spectrometry.

[0124] The results are shown in Table 2. The impurities shown in Table 2 are impurity elements (excluding O, H, S and N).

[0125] (Density of the sculpture)

[0126] The density of the stacked structure was evaluated based on its cross-section and the area occupied by the pores observed within that cross-section. In this specification, this density is defined as the structure density.

[0127] Regarding the evaluation of the density of the sculpture, after defining the cross-sectional area of ​​the object to be measured in the cross-section of the sculpture (referred to as the evaluation cross-sectional area, 3.4 mm square), the pores located inside this measurement cross-sectional area are identified, and the area occupied by the pores in the evaluation cross-sectional area is calculated. Then, (evaluation cross-sectional area - pore area) / evaluation cross-sectional area is defined as the density of the sculpture. The evaluation results of the density of the sculpture are shown in Table 2.

[0128] [Table 1]

[0129]

[0130] [Table 2]

[0131]

[0132] As shown in Table 2, it was confirmed that by using the copper alloy powder for metal AM of the present invention for layering and molding, the density of the molded object reached 99.3%. On the other hand, it was confirmed that when using the conventional C18000 powder for metal AM, the density of the molded object was 97.3%, which is a problematic density in practical use.

[0133] Based on the above results, it has been confirmed that by using the copper alloy powder for metal AM manufactured by the manufacturing method of the present invention, it is possible to manufacture laminated shapes with sufficiently high density and few pores.

[0134] In addition, it can be considered that the O concentration of the copper alloy powder for metal AM in this invention is higher than the O concentration of the ingot in Table 1. However, since the original copper alloy ingot is of high purity, it can suppress the increase of excess O concentration in subsequent processes, which can help improve the reproducibility of the microstructure of the laminated model.

[0135] According to the present invention, a method for manufacturing copper alloy powder for metal AM has been found that can stably manufacture high-quality laminated models with high reproducibility of the fine structure of the laminated model made by metal AM and few structural defects such as pores.

[0136] Symbol Explanation

[0137] S14 - Continuous casting process; S32 - Atomization treatment process.

Claims

1. A method for manufacturing copper alloy powder for metallic AM, characterized in that, have: The casting process manufactures copper alloy ingots using a casting apparatus comprising: a copper molten metal supply unit for melting copper raw materials composed of high-purity copper with a purity of 99.99% by mass or higher to obtain copper molten metal; a tundish disposed downstream of the copper molten metal supply unit and holding the copper molten metal; a connecting tank disposed between the copper molten metal supply unit and the tundish and supplying the copper molten metal to the tundish; and an additive unit for adding copper alloying elements to the copper molten metal to obtain copper alloy molten metal. And a mold, supplied with the molten copper alloy; and The atomization process involves using the copper alloy ingot as raw material, atomizing it in an inert gas or vacuum atmosphere to melt and decompose it, thereby pulverizing it. In the casting process, the copper molten metal supply unit, the tundish, the connecting tank, and the additive unit are in a non-oxidizing atmosphere. The copper alloy ingot has an O concentration of less than 10 ppm by mass, an H concentration of less than 5 ppm by mass, and a total O, H, and S concentration of less than 20 ppm by mass. Furthermore, the total content of impurity elements other than Cu and alloying elements is less than 0.04% by mass, wherein the impurity elements are elements other than O, H, and S. In the copper alloy powder for AM metal obtained in the atomization process, the total amount of impurity elements other than alloying elements is less than 0.07% by mass, wherein the impurity elements are elements other than O, H, S and N.

2. The method for manufacturing copper alloy powder for metallic AM according to claim 1, characterized in that, The concentration of O in the copper alloy ingot is below 8 ppm by mass, and the concentration of H is below 3 ppm by mass.

3. The method for manufacturing copper alloy powder for metallic AM according to claim 1 or 2, characterized in that, The total content of the alloying elements in the copper alloy ingot is in the range of more than 0.01% by mass and less than 5% by mass.

4. The method for manufacturing copper alloy powder for metallic AM according to claim 1 or 2, characterized in that, The alloy contains one or more of the following alloying elements: Cr, Zr, Si, Ni, Mg, Ti, Al, Zn, Ca, Sn, Pb, Fe, Mn, Te, Nb, Co, Sb, Bi, Ag, Ta, W, Mo, and P.

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