Method for producing copper alloy powder for metal AM

Abstract

This method for producing a copper alloy powder for metal AM comprises: a casting step for producing a copper alloy ingot by means of a casting device provided with: a molten copper supply unit for obtaining a molten copper by melting a copper raw material comprising high-purity copper having a purity of 99.99 mass% or more; an addition unit for obtaining a copper alloy melt by adding an alloy element of a copper alloy to the copper melt in a non-oxidizing atmosphere; and a mold to which the molten copper alloy is supplied. And an atomization treatment step in which the copper alloy ingot having an O concentration of 10 ppm by mass or less and an H concentration of 5 ppm by mass or less is pulverized by being atomized in an inert gas or vacuum atmosphere as a raw material and melted and decomposed.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a copper alloy powder for metal additive manufacturing (metal AM) that is most suitable for metal AM technology.

[0002] This application claims priority based on Japanese Patent Application No. 2022-169920 filed on October 24, 2022, and incorporates its content herein by reference. Background Art

[0003] In recent years, as a method for manufacturing metal components with various three-dimensional shapes, metal AM technology that mainly uses powder as a raw material and shapes products through a metal 3D printer has been put into practical use. As the main metal AM technologies using metal powder, there can be mentioned powder bed fusion methods (powder bed fusion: PBF) using electron beams or laser beams, binder jetting methods, and the like.

[0004] Here, copper alloys have various basic properties suitable for industrial applications such as electrical conductivity, thermal conductivity, mechanical properties, wear resistance, and heat resistance, and are used as raw materials for various components. Therefore, in recent years, in various fields such as space and electrical component applications, attempts have been made to form various-shaped components by metal AM using copper alloy powder, and the demand for copper and copper alloy components manufactured by metal AM is increasing.

[0005] For example, in Patent Documents 1 and 2, technologies for manufacturing a laminated molded object based on metal AM using copper alloy powder are proposed.

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

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

[0008] Non-Patent Document 1: Y.M. Arisoy et.al., "Influence of scan strategy and process parameters on microstructure and its optimization in additively manufactured nickel alloy 625 via laser powder bed fusion", The International Journal of Advanced Manufacturing Technology, Volume 90, p.p. 1393-1417 (2017).

[0009] The metal structure formed by metal AM is used as a certain structural component according to various uses. Therefore, when there are pores in the laminated structure or the microstructure of the metal material is uneven, it becomes a problem in terms of thermomechanical and electrical reliability.

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

[0011] However, when performing laminated shaping by irradiating a laser beam or an electron beam, first, a relatively thin powder layer (powder bed) is formed, and then, the powder bed is locally irradiated with a laser beam or an electron beam to melt and solidify the material. However, for copper and copper alloys, compared with other metal materials such as iron, titanium, and nickel-based alloys, copper itself has a high reflectivity to visible light and infrared light. Therefore, during the laser PBF process, the melting behavior of copper alloy powder becomes unstable, and pores are likely to be generated inside the fabricated laminated structure. As a result, problems such as unstable quality and poor productivity of the shaped body manufactured by laser PBF emerge in an endless stream, and it is required to improve the quality and productivity of copper and copper alloys manufactured by laser PBF.

[0012] Currently, the most widely used form of raw material for metal AM is powder. For example, in metal AM using laser PBF, the absorption characteristics of the particles to electromagnetic waves caused by the coupling / interaction of the surface layer of each particle constituting the raw material powder with electromagnetic waves will affect the melting behavior of the raw material powder and will have a great impact on the quality including the productivity of the component and the defect density of the component. For example, in the metal AM process using a powder bed, the thickness of the powder bed formed in one lamination process is, for example, about several tens of micrometers (Non-Patent Document 1). The raw material powder is melted by irradiating the converging electromagnetic waves onto such a relatively thin powder bed, and further, multiple laminations and melting and solidification are repeatedly performed to realize the desired shaping structure. What has a great impact on the basic process of such laminated shaping using a powder bed is the absorption characteristics of solids to electromagnetic waves. 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 the microstructure of the powder becomes extremely important in terms of achieving stable quality and high productivity in the overall laminated structure.

[0013] Moreover, as a result of various past research and development efforts on copper alloys, materials that maintain high electrical conductivity while achieving high mechanical strength, materials with excellent heat resistance, etc. have been developed. For metal AM, there is also a social demand to use materials composed of existing high-performance copper alloys to realize metal AM components with desired shapes. However, when irradiating a laser beam or an electron beam on a powder bed of raw materials composed of such known copper alloys for layer forming, and in the case of a lack of reproducibility of the fine structure related to the raw material powder, including the compositional reproducibility of the powder particles in each part irradiated with the laser beam, etc., the melting behavior of the powder becomes uneven. As a result, it is possible to cause structural defects such as pores inside the formed body, or to deteriorate the mechanical properties due to the non-uniformity of the metal composition of the formed body.

[0014] This reproducibility of the fine structure of the raw material powder includes the compositional reproducibility of the powder material, and the same problem also exists in other metal AM processes such as the binder jetting method. Especially in the layer forming of copper alloys, due to these various raw material problems, the improvement of productivity is a major issue. In the existing copper alloy powders for metal AM, the material characteristics suitable for the metal AM process are insufficient. As a result, defects are likely to occur in the formed bodies manufactured by various layer forming processes, and sufficient productivity has not been achieved.

[0015] Moreover, as one of the factors causing structural defects in metal AM formed bodies, there is the generation of pores caused by the entrainment of gases, etc. When layer forming is performed by the PBF method using existing copper alloy powders, when melting the powder, gases are generated due to impurities contained in the copper alloy powders. The molten copper alloy or the solidified copper alloy captures the gas components, and sometimes pores are generated inside the produced layer formed object, and it may not be possible to produce a stable and high-quality layer formed object. Summary of the Invention

[0016] The present invention has been completed in view of the foregoing circumstances, and an object thereof is to provide a method for manufacturing a copper alloy powder for metal AM, which can stably manufacture a high-quality layer formed object with high reproducibility of the fine structure and few structural defects such as pores by metal AM.

[0017] To solve this problem, as a result of intensive research by the present inventors, it has been found that when using powders manufactured by an atomization treatment process, the generation of pores inside the produced layer formed object can be significantly suppressed. The atomization treatment process melts and decomposes a high-purity copper alloy ingot with sufficiently reduced O concentration and H concentration as a raw material by atomization treatment in an inert gas or vacuum atmosphere, thereby making it into powder.

[0018] Regarding pore suppression in the laser PBF process, it can be considered that by improving the purity of the copper alloy powder used as the raw material, the reproducibility of the material composition in the entire powder is improved. That is, as a result of the improved reproducibility of the powder composition in each part of the powder bed irradiated with the laser, the reproducibility of the melting / solidification behavior of the raw material powder caused by laser irradiation is improved and stabilized, and the H 2 O and other off-gas components that may be generated due to O and H in the laser raw material powder are suppressed. Through such effects, etc., the generation of pores in the laminated object can be suppressed.

[0019] The present invention has been completed based on the above insights. The manufacturing method of the copper alloy powder for metal AM according to aspect 1 of the present invention is a manufacturing method of the copper alloy powder for metal AM used for metal AM, and is characterized by having: a casting process for manufacturing a copper alloy ingot by a casting device, the casting device including: a copper melt supply part for melting a copper raw material composed of high-purity copper with a purity of 99.99 mass% or more to obtain a copper melt; an addition part for adding alloy elements of the copper alloy to the copper melt in a non-oxidizing atmosphere to obtain a copper alloy melt; and a mold for supplying the copper alloy melt; and an atomization treatment process for using the copper alloy ingot as a raw material and performing atomization treatment in an inert gas or vacuum atmosphere to melt and decompose it, thereby making it powdered. The O concentration in the copper alloy ingot is 10 mass ppm or less, and the H concentration is 5 mass ppm or less.

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

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

[0022] According to the manufacturing method of the copper alloy powder for metal AM according to aspect 2 of the present invention, since the S concentration in the copper alloy ingot is 15 mass ppm or less, S, which is an element that is easily contained in copper, can be sufficiently reduced. A copper alloy powder for metal AM can be manufactured by using the copper alloy ingot as a raw material. This copper alloy powder for metal AM can stably manufacture a higher-quality laminated object with high reproducibility of fine structures and few structural defects such as pores.

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

[0024] According to the method for manufacturing a copper alloy powder for metal AM according to Aspect 3 of the present invention, since the total of the O concentration, H concentration, and S concentration in the copper alloy ingot is 30 mass ppm or less, a copper alloy powder for metal AM can be manufactured by using the copper alloy ingot as a raw material, and a higher-quality laminated object with high reproducibility of fine structures and few structural defects such as pores can be stably manufactured.

[0025] Regarding Aspect 4 of the present invention, in the method for manufacturing a copper alloy powder for metal AM according to any one of Aspects 1 to 3, it is preferable that the total content of the alloy elements in the copper alloy ingot is in the range of 0.01 mass% or more and 50 mass% or less.

[0026] According to the method for manufacturing a copper alloy powder for metal AM according to Aspect 4 of the present invention, since the total content of the alloy elements in the copper alloy ingot is in the range of 0.01 mass% or more and 50 mass% or less, a copper alloy powder for metal AM with a uniform content of alloy elements can be stably manufactured.

[0027] Moreover, since it contains alloy elements, a copper alloy powder for metal AM with excellent various properties such as electrical conductivity and thermal conductivity can be manufactured.

[0028] Regarding Aspect 5 of the present invention, in the method for manufacturing a copper alloy powder for metal AM according to any one of Aspects 1 to 4, it is preferable to contain one or more 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 as the alloy elements.

[0029] According to the method for manufacturing a copper alloy powder for metal AM according to Aspect 5 of the present invention, since it contains any one or more of the above alloy elements as alloy elements, a copper alloy powder for metal AM with excellent various properties such as electrical conductivity and thermal conductivity can be manufactured.

[0030] Regarding Aspect 6 of the present invention, in the method for manufacturing a copper alloy powder for metal AM according to any one of Aspects 1 to 5, it is preferable that in the casting process, the copper alloy ingot is continuously manufactured by a continuous casting device.

[0031] The method for manufacturing a copper alloy powder for metal AM according to aspect 6 of the present invention has excellent production efficiency of the copper alloy ingot because the copper alloy ingot is continuously manufactured by a continuous casting device. Further, the method for manufacturing a copper alloy powder for metal AM according to aspect 6 of the present invention can obtain a copper alloy ingot with a stable content of alloy elements by continuous casting, and thus can stably manufacture a copper alloy powder for metal AM with a uniform content of alloy elements.

[0032] According to the present invention, there can be provided a method for manufacturing a copper alloy powder for metal AM, and the copper alloy powder for metal AM can stably manufacture a high-quality laminated object with high reproducibility of the fine structure of the laminated object produced by metal AM and few structural defects such as pores. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 is a flowchart of the method for manufacturing a copper alloy powder for metal AM of the present embodiment.

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

[0035] Figure 3 is a flowchart of the process for producing a copper alloy raw material in the method for manufacturing a copper alloy powder for metal AM of the present embodiment.

[0036] Figure 4 is a flowchart of the atomization treatment process in the method for manufacturing a copper alloy powder for metal AM of the present embodiment.

[0037] Figure 5 is a schematic explanatory view of the continuous casting device used in the method for manufacturing a copper alloy powder for metal AM of the present embodiment.

[0038] Figure 6 is a schematic explanatory view of another continuous casting device used in the method for manufacturing a copper alloy powder for metal AM of the present embodiment. DETAILED DESCRIPTION OF THE EMBODIMENTS

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

[0040] The method for manufacturing a copper alloy powder for metal AM of the present embodiment manufactures a copper alloy powder for metal AM. Further, in the present embodiment, a copper alloy powder suitable for the laser PBF method is manufactured.

[0041] Regarding the method for manufacturing a copper alloy powder for metal AM of the present embodiment, use Figure 1 of the flowchart for explanation.

[0042] The manufacturing method of the 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 production process S02 for processing the obtained copper alloy ingot into a wire rod and using it as a copper alloy raw material; and a powder processing process S03 for processing the copper alloy raw material 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 shown in the flowchart of Figure 2 , it has a melting process S11, an alloy element addition process S12, and a continuous casting process S13.

[0045] Then, in this embodiment, the continuous casting device 10 shown in Figure 5 is used to obtain the copper alloy ingot 1.

[0046] This continuous casting device 10 includes: a melting furnace 11; a tundish 12 disposed downstream of the melting furnace 11; a connecting trough 13 connecting the melting furnace 11 and the tundish 12; an addition part 14 for adding alloy elements to the tundish 12; a continuous casting mold 15 disposed on the downstream side of the tundish 12; and a pouring nozzle 16 for injecting the copper alloy melt from the tundish 12 into the continuous casting mold 15.

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

[0048] Here, the copper raw materials melted in the melting furnace 11 are high-purity copper with a copper purity of 99.99 mass% or more (for example, high-purity electrolytic copper or oxygen-free copper). In addition, the melted copper raw materials are high-purity copper of 4N grade (99.99 mass%) or more, but more preferably 5N grade (99.999 mass%) or more, and even more preferably 6N (99.9999 mass%) or more. And the obtained copper melt 3 is preferably an oxygen-free copper melt.

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

[0050] And, in the tundish 12, the copper melt 3 is maintained in a non-oxidizing atmosphere (non-reactive gas atmosphere or reducing gas atmosphere).

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

[0052] Moreover, in the tundish 12, alloying elements are added to the copper melt 3 using the addition part 14 (alloying element addition step S12).

[0053] By adding alloying elements to the copper melt 3 with sufficiently reduced gas components (O, H), the addition yield of the alloying elements is good. Therefore, the usage amount of the alloying elements can be reduced, and the manufacturing cost of the copper alloy can be reduced.

[0054] Furthermore, by adding alloying elements to the copper melt 3 flowing in the tundish 12, the alloying elements can be uniformly melted, enabling the continuous production of a copper alloy melt with a stable component value.

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

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

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

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

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

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

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

[0062] Next, the copper alloy ingot 1 obtained in the melting / casting process S01 is processed into a wire rod to produce a copper alloy raw material.

[0063] In this copper alloy raw material production process S02, as Figure 3 shown, an extrusion process S21, a drawing process S22, and a cutting process S23 are provided.

[0064] In the extrusion process S21, the copper alloy ingot having a circular cross-section is heated and formed into a rod having a specified diameter by hot extrusion processing.

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

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

[0067] In addition, the temperature of the drawing process is not particularly limited, and it is preferably within the range of -200°C to 200°C which becomes cold rolling or hot rolling, and particularly preferably at room temperature.

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

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

[0070] Further, the S concentration in the obtained copper alloy raw material is preferably 15 mass ppm or less.

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

[0072] (Powder processing process S03)

[0073] Next, by using the copper alloy raw material obtained in the copper alloy raw material production process S02, atomization treatment is performed to manufacture copper alloy powder for metal AM.

[0074] In this powder processing process S03, as Figure 4 shown, it includes a melting process S31, an atomization treatment process S32, and a classification process S33.

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

[0076] In the atomization treatment process S32, by spraying the metal melt obtained in the melting process S31 with high-pressure gas, the droplets of the metal melt are rapidly cooled to manufacture spherical or spherical-like powders. As the gas used for the gas atomization method, inert gases such as argon and nitrogen can be used. The melting temperature of the copper alloy raw material in the gas atomization treatment (the melting temperature during the gas atomization treatment) is preferably above the melting point of copper and below 1500 °C. The melting temperature during the gas atomization treatment can be above 1085 °C and below 1500 °C.

[0077] In the classification process S33, the obtained powders are classified to obtain copper alloy powders having a specified particle size distribution.

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

[0079] Regarding the copper alloy powder for metal AM manufactured by the manufacturing method of the copper alloy powder for metal AM of the present embodiment, as described above, it contains various alloy elements.

[0080] In the present embodiment, the alloy element refers to an element intentionally added in the manufacturing method of the copper alloy powder for metal AM of the present embodiment. In the present embodiment, sometimes a part of the alloy element is called an active metal element.

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

[0082] The alloy element is not limited to the above components, and it is preferable to contain one or more 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 as alloy elements.

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

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

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

[0086] In addition, in the copper alloy powder for metal AM, impurity elements (excluding O, H, S, and N) may be contained within a range that does not affect the properties.

[0087] The impurity elements (excluding O, H, S, and N) refer to components that are not intentionally mixed but are contaminants from the manufacturing process or trace impurities contained in the raw materials. In the present embodiment, the impurity elements may be inevitable impurities.

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

[0089] Moreover, in the process implemented under limited pressure such as atomization treatment, the powder may contain atmosphere components due to the atmosphere components contained in the atmosphere or the process. For example, nitrogen may be contained in the powder as an atmosphere component. In the copper alloy powder for metal AM of the present embodiment, the nitrogen concentration (N concentration) is preferably 30 mass ppm, more preferably 20 mass ppm, and further preferably 10 mass ppm or less. Moreover, in the copper alloy powder for metal AM of the present embodiment, the nitrogen concentration (N concentration) is further preferably 5 mass ppm or less. And the lower limit value of the N concentration is not particularly limited and may be a value not including 0 (or a value exceeding 0).

[0090] In addition, in the composition of the copper alloy of the copper alloy particles 50 constituting the copper alloy powder for metal AM, the error in numerical accuracy is ±10% (excluding O, H, S, and N)

[0091] Moreover, the copper alloy powder for metal AM manufactured by the manufacturing method of the copper alloy powder for metal AM according to the present embodiment contains one or more alloy elements selected from Cr, Zr, Si, and Ni. The total content of the alloy 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, still more preferably in the range of 0.01% by mass or more and 5% by mass or less, and can also be 0.02% by mass or more. Moreover, the alloy elements of the copper alloy powder for metal AM manufactured by the present embodiment are not limited to the above components. As the alloy elements (active metal elements), 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 can be cited. Furthermore, the O concentration in the copper raw material composed of oxygen-free copper is 10 mass ppm or less, and the H concentration is 5 mass ppm or less. Therefore, the O concentration and H concentration of the copper alloy powder for metal AM manufactured by the manufacturing method of the copper alloy powder for metal AM according to the present embodiment are low.

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

[0093] In the manufacturing method of the copper alloy powder for metal AM of the present embodiment, when the S concentration in the copper alloy ingot is 15 mass ppm or less, it is possible to sufficiently reduce S, which is an element that is easily contained in copper. By using this copper alloy ingot as a raw material to manufacture a copper alloy powder, it is possible to manufacture a copper alloy powder for metal AM that can stably manufacture a higher-quality laminated object with high reproducibility of fine structures and few structural defects such as pores.

[0094] In the manufacturing method of the copper alloy powder for metal AM of the present embodiment, when the total content of impurity elements (excluding O, H, and S) other than Cu and alloy elements in the copper alloy ingot is 0.04% by mass or less, the amount of impurity elements is sufficiently reduced. By using this copper alloy ingot as a raw material to manufacture a copper alloy powder, it is possible to manufacture a copper alloy powder for metal AM that can stably manufacture a higher-quality laminated object with high reproducibility of fine structures and few structural defects such as pores.

[0095] In the method for manufacturing a copper alloy powder for metal AM according to this embodiment, in the case of containing alloy elements, it is possible to manufacture a copper alloy powder for metal AM that can realize a copper alloy molded body having excellent various properties such as electrical conductivity and thermal conductivity.

[0096] Moreover, a copper alloy ingot with a stable content of alloy elements can be obtained by the continuous casting device 1, and a copper alloy powder for metal AM with a uniform content of alloy elements can be stably manufactured. It is considered that in the copper alloy powder for metal AM, such a state where the content of alloy elements is uniform realizes uniform energy absorption throughout the powder bed, for example, in the molding process of PBF using an electron beam or a laser beam. As a result, a laminated molded object with high reproducibility and high reliability is realized.

[0097] In the method for manufacturing a copper alloy powder for metal AM according to this embodiment, in the case of continuously manufacturing a copper alloy ingot by the continuous casting device 10, the copper alloy ingot 1 can be effectively manufactured.

[0098] The above has described the method for manufacturing a copper alloy powder for metal AM according to the embodiment of the present invention, but the present invention is not limited thereto, and can be appropriately changed within the scope not departing from the technical idea of the invention.

[0099] For example, in the above embodiment, the method of manufacturing powder by the gas atomization method has been described, but it is not limited thereto, and copper alloy powder can also be manufactured by the water atomization method, the centrifugal atomization method, the inductively coupled plasma method, the plasma atomization method, etc.

[0100] Moreover, heat treatment can be appropriately performed on the copper alloy powder for metal AM obtained as described above to achieve stabilization of the structure, etc. At the time of this heat treatment, an appropriate atmosphere such as an inert gas or a vacuum can be selected.

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

[0102] Moreover, in this embodiment, the use of Figure 5 The method of manufacturing a copper alloy ingot using the shown continuous casting device has been described, but it is not limited thereto, and other casting devices can also be used.

[0103] For example, it is possible to use Figure 6The continuous casting apparatus 101 shown. The continuous casting apparatus 101 includes: an oxygen-free copper supply mechanism (copper melt supply section) 102 disposed at the uppermost upstream portion; a heating furnace 103 disposed downstream thereof; a tundish 104 disposed downstream of the heating furnace 103 and supplying the copper melt; melt supply channels 105a, 105b, 105c connecting the oxygen-free copper supply mechanism 102 to the heating furnace 103; a trough 106 connecting the heating furnace 103 and the tundish 104; addition mechanisms (addition sections) 107, 108 for adding alloy elements in a non-oxidizing atmosphere; and a continuous casting mold 142. Further, the interiors of the oxygen-free copper supply mechanism 102, the heating furnace 103, the tundish 104, the melt supply channels 105a, 105b, 105c, and the trough 106 are each set to a non-oxidizing atmosphere.

[0104] The oxygen-free copper supply mechanism 102 is composed of a melting furnace 121 for melting a copper raw material, 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 melt supply channels 105a, 105b, 105c connecting them.

[0105] The degassing treatment device 124 has a gas bubbling device as a stirring mechanism to stir the molten copper therein, and removes oxygen and hydrogen from the molten copper, for example, by performing bubbling based on an inert gas.

[0106] In order to prevent the molten copper and the oxygen-free copper melt from being oxidized, the interiors of the melt supply channels 105a, 105b, 105c are set to a non-oxidizing atmosphere. This non-oxidizing atmosphere is formed, for example, by blowing a mixed gas of nitrogen and carbon monoxide, an inert gas such as argon, into the melt supply channel.

[0107] As an addition mechanism for adding alloy elements, a first addition mechanism 107 disposed in the heating furnace 103 and a second addition mechanism 108 disposed in the tundish 104 are provided.

[0108] If alloy elements are continuously or intermittently charged from the first addition mechanism 107 provided in the heating furnace 103, the alloy elements are added to the oxygen-free copper melt stored in the heating furnace 103. Here, the oxygen-free copper melt stored in the storage section is heated by a high-frequency induction coil to promote the melting of the added alloy elements.

[0109] Moreover, if alloy elements are continuously or intermittently charged from the second addition mechanism 108 provided in the tundish 104, the alloy elements are added to the oxygen-free copper melt flowing in the tundish 104. Here, the oxygen-free copper melt flowing in the tundish 104 is heated in the heating furnace 103 to become high temperature and flows in the tundish 104, thus promoting the melting of the added alloy elements.

[0110] Examples

[0111] In order to verify the effects of the present invention, the following confirmation experiments were conducted.

[0112] (Example of the present invention)

[0113] First, by the manufacturing method described in the embodiment, a C18000 ingot having the composition shown in Table 1 was produced using a copper raw material composed of 4N grade high-purity copper.

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

[0115] Next, using the produced C18000 ingot as a raw material, a copper alloy powder for metal AM having the composition shown in Table 2 was produced by a gas atomization method using argon, and sieved into a particle size suitable for a powder bed of metal AM. The melting temperature during the gas atomization treatment was carried out under the condition of 1300 °C.

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

[0117] Then, using the copper alloy powder for metal AM of the example of the present invention and a commercially available laser PBF apparatus, small pieces of a laminated structure were produced under the condition of an energy density of 13 J / mm 2 2.

[0118] (Existing example)

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

[0120] Regarding the C18000 powder for metal AM of the existing example, as a result of measuring the particle size distribution using MT3300EXII manufactured by MICRO TRACK CO., LTD., the particle size distribution was such that the 10% cumulative particle size based on volume was 13 μm, the 50% cumulative particle size was 33 μm, and the 90% cumulative particle size was 57 μm.

[0121] Then, using the C18000 powder for metal AM of the existing example and a commercially available laser PBF apparatus, small pieces of a laminated structure were produced under the same shaping conditions as in the example of the present invention including the lamination thickness.

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

[0123] The O concentration in the ingot shown in Table 1, the copper alloy powder for metal AM of the present invention example, and the copper alloy powder for metal AM of the existing example was determined by inert gas fusion-infrared absorption method, the H concentration was determined by inert gas fusion-thermal conductivity method, and the S concentration was determined by combustion-infrared absorption method. And, excluding copper, the concentrations of the components other than these substances were determined by combining fluorescence X-ray 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 molded object)

[0126] Based on the cross-section of the fabricated laminated object and the area occupied by the pores observed in the cross-section of the laminated object, the density of the laminated object was evaluated. In this specification, this density is defined as the density of the molded object.

[0127] Regarding the evaluation of the density of the molded object, after defining the cross-sectional area of the measurement object in the cross-section of the molded object (which is called the evaluation cross-sectional area, 3.4 mm square), the pore parts located inside the measurement cross-sectional area were confirmed, and the occupied area of the pores in the evaluation cross-sectional area was calculated. Then, (evaluation cross-sectional area - pore occupied area) / evaluation cross-sectional area was defined as the density of the molded object. The evaluation results of the density of the molded object 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 example for laminated modeling, the density of the molded object reached 99.3%. On the other hand, it was confirmed that in the case of using the C18000 powder for metal AM of the existing example, the density of the molded object was 97.3%, which is a density that causes problems in actual use.

[0133] Based on the above results, it was confirmed that by using the copper alloy powder for metal AM manufactured by the manufacturing method of the copper alloy powder for metal AM of the present invention, a laminated object with a sufficiently high density and few pores can be manufactured.

[0134] In addition, it can be considered that the O concentration of the copper alloy powder for metal AM in the example of the present invention is higher than that of the ingot in Table 1. However, since the original copper alloy ingot is of high purity, it is possible to suppress the increase in the excessive O concentration in the subsequent processes, which can contribute to improving the reproducibility of the fine structure of the laminated object.

[0135] According to the present invention, it has been confirmed that a manufacturing method of a copper alloy powder for metal AM can be provided, and the copper alloy powder for metal AM can stably manufacture a high-quality laminated object with high reproducibility of the fine structure of the laminated object produced 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 manufacturing method of copper alloy powder for metal AM, characterized in that, it has: a casting process, in which a copper alloy ingot is manufactured by a casting device, and the casting device includes: a copper melt supply part that melts a copper raw material composed of high-purity copper with a purity of 99.99 mass% or more to obtain a copper melt; an addition part that adds alloy elements of the copper alloy to the copper melt in a non-oxidizing atmosphere to obtain a copper alloy melt; and a mold that is supplied with the copper alloy melt; and an atomization treatment process, in which the copper alloy ingot is used as a raw material and atomized and decomposed by atomization treatment in an inert gas or vacuum atmosphere, thereby being powdered, the O concentration in the copper alloy ingot is 10 mass ppm or less, and the H concentration is 5 mass ppm or less.

2. The manufacturing method of copper alloy powder for metal AM according to claim 1, characterized in that, the S concentration in the copper alloy ingot is 15 mass ppm or less.

3. The manufacturing method of copper alloy powder for metal AM according to claim 1 or 2, characterized in that, the total of the O concentration, H concentration and S concentration in the copper alloy ingot is 30 mass ppm or less.

4. The manufacturing method of copper alloy powder for metal AM according to claim 1 or 2, characterized in that, the total content of the alloy elements in the copper alloy ingot is in the range of 0.01 mass% or more and 50 mass% or less.

5. The manufacturing method of copper alloy powder for metal AM according to claim 1 or 2, characterized in that, it contains one or more 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 as alloy elements.

6. The manufacturing method of copper alloy powder for metal AM according to claim 1 or 2, characterized in that, in the casting process, the copper alloy ingot is continuously manufactured by a continuous casting device.

Images