Copper-based alloy powder and its manufacturing method

Abstract

This copper-based alloy powder is composed of an aggregate of copper-based alloy particles containing copper and nickel. Within the copper-based alloy particles contained in the copper-based alloy powder, the NiO segregated particle abundance rate, which is the numeric ratio of particles in which the area ratio of NiO is 2% or higher when observed in cross-section, is 4.0% by number or lower. The nickel content is preferably 1.0-20.0 mass%. Additionally, the copper content is preferably 80.0-99.9 mass%. Additionally, the phosphorus content is preferably 0.007-0.5 mass%.

Description

[Technical Field]

[0001] The present invention relates to a copper-based alloy powder and a method for producing the same. [Background technology]

[0002] Atomization is known as a relatively inexpensive method for producing alloy powders for various applications such as electronic materials, powder metallurgy, and paints. For example, Patent Document 1 describes a method in which copper raw material blocks and nickel raw material blocks are melted in a crucible, and the resulting molten metal is used to produce copper-nickel alloy powder by gas atomization. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2018 / 207770 Brochure Summary of the Invention

[0004] Alloy powder obtained by atomization is generally classified to obtain a particle size distribution suitable for the desired application. The non-grade powder removed by classification can be melted and reused as a raw material for atomization. However, when copper-nickel alloy powder obtained by a conventional atomization method such as that described in Patent Document 1 is melted and reused as a raw material for atomization, dross is generated in the molten metal obtained by melting the copper-nickel alloy powder, which results in a problem of a reduced yield of the copper-nickel alloy powder obtained using the molten metal. Therefore, an object of the present invention is to provide a copper-based alloy powder that can suppress the generation of dross when melted, and a method for producing the same.

[0005] The present invention provides a copper-based alloy powder comprising an aggregate of copper-based alloy particles containing copper and nickel, The copper-based alloy powder is provided, in which the presence rate of NiO segregated particles, which is the number ratio of particles having an NiO area rate of 2% or more when cross-sectionally observed, among the copper-based alloy particles contained in the copper-based alloy powder is 4.0% or less by number.

[0006] The present invention also provides a method for producing a molten metal comprising: a melting step for obtaining a molten metal containing copper and nickel; a granulation step of using the molten metal by an atomization method to obtain a copper-based alloy powder comprising an aggregate of copper-based alloy particles containing copper and nickel, The present invention provides a method for producing a copper-based alloy powder, wherein an induction furnace is used in the melting step, and the output of the induction furnace is set to 100 kW or more to obtain the molten metal. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 1 is a scanning electron microscope image showing a cross section of the copper-based alloy powder of the present invention. [Figure 2] FIG. 2 is an image showing the area of ​​the cross section shown in FIG. 1 where the area is to be measured. [Figure 3] FIG. 3 is an image showing the NiO region observed in the cross section shown in FIG. [Figure 4] FIG. 4 is an image showing a region not included in the NiO region shown in FIG. [Figure 5] FIG. 5 is an image showing another region of NiO observed in the cross section shown in FIG. [Figure 6] FIG. 6 is an image showing yet another region of NiO observed in the cross section shown in FIG. [Figure 7] FIG. 7 is a graph showing the relationship between the temperature of the molten metal employed in the examples and comparative examples and the abundance ratio of NiO segregated particles in the copper-based alloy powder. DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention will be described below based on preferred embodiments. The present invention relates to a copper-based alloy powder. The copper-based alloy powder is composed of an aggregate of copper-based alloy particles. The copper-based alloy powder of the present invention consists essentially of copper-based alloy particles, but may contain unavoidable impurities. When the copper-based alloy powder of the present invention contains unavoidable impurities, the amount of such impurities is preferably 0.01 mass % or less, since the inherent properties of the copper-based alloy powder are less likely to be impaired.

[0009] The copper-based alloy particles are made of an alloy mainly composed of copper and containing elements other than copper. The other elements may be, for example, metallic elements or non-metallic elements. For example, nickel may be used as a metallic element, while phosphorus may be used as a non-metallic element. An example of copper-based alloy particles is particles of an alloy containing copper and nickel, with the balance being unavoidable impurities. Another example of copper-based alloy particles is particles of an alloy containing copper, nickel, and phosphorus, with the balance being unavoidable impurities.

[0010] From the viewpoint of sufficiently increasing the electrical conductivity of the copper-based alloy powder, the copper content in the copper-based alloy particles is preferably 80.0 mass % or more, more preferably 85.0 mass % or more, and even more preferably 87.0 mass % or more. Furthermore, from the viewpoint of sufficiently increasing the oxidation resistance of the copper-based alloy powder, the copper content in the copper-based alloy particles is preferably 99.9 mass% or less, more preferably 95.0 mass% or less, and even more preferably 92.0 mass% or less.

[0011] From the viewpoint of sufficiently increasing the oxidation resistance of the copper-based alloy powder, the nickel content in the copper-based alloy particles is preferably 1.0 mass% or more, more preferably 5.0 mass% or more, and even more preferably 8.0 mass% or more. Furthermore, from the viewpoint of sufficiently increasing the electrical conductivity of the copper-based alloy powder, the nickel content in the copper-based alloy particles is preferably 20.0 mass % or less, more preferably 15.0 mass % or less, and even more preferably 13.0 mass % or less.

[0012] When the copper-based alloy particles contain phosphorus, the phosphorus content is preferably 0.007% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.012% by mass or more, and even more preferably 0.013% by mass or more, from the viewpoint of sufficiently increasing the oxidation resistance of the copper-based alloy powder. Furthermore, from the viewpoint of sufficiently increasing the electrical conductivity of the copper-based alloy powder, the phosphorus content in the copper-based alloy particles is preferably 0.5 mass % or less, more preferably 0.2 mass % or less, and even more preferably 0.1 mass % or less. The reason why the oxidation resistance of copper-based alloy particles increases when phosphorus is included is that during the manufacturing process of the copper-based alloy particles, phosphorus is sacrificially oxidized instead of nickel being oxidized, effectively suppressing the segregation of NiO (an oxide formed by the combination of divalent nickel and divalent oxygen, as described below).In addition, phosphorus sublimes after sacrificial oxidation, so it is less likely to remain in the copper-based alloy particles, which is advantageous in that it is less likely to reduce the electrical conductivity of the copper-based alloy particles. When the copper-based alloy particles contain phosphorus, it is preferable that the phosphorus be added to the copper-containing molten metal as, for example, Cu3P, as described later in the description of a preferred method for producing copper-based alloy particles.

[0013] The proportions of copper, nickel, and phosphorus contained in the copper-based alloy particles can be measured by ICP atomic emission spectroscopy of a sample solution obtained by dissolving the copper-based alloy particles in an acid such as hydrochloric acid.

[0014] The copper-based alloy particles preferably contain a small amount of oxygen in order to sufficiently enhance the electrical conductivity of the copper-based alloy powder. From this viewpoint, the oxygen content in the copper-based alloy particles is preferably 1.0 mass% or less, more preferably 0.8 mass% or less, even more preferably 0.7 mass% or less, even more preferably 0.65 mass% or less, and particularly preferably 0.6 mass% or less. The smaller the amount of oxygen contained in the copper-based alloy particles, the better from the viewpoint of improving electrical conductivity, and the most preferable amount is zero.

[0015] The oxygen content of the copper-based alloy particles of the present invention can be measured by the following method. For example, an oxygen / nitrogen analyzer EMGA-920 manufactured by Horiba, Ltd. can be used. 1 g of copper-based alloy powder is weighed, placed in a nickel capsule, and then combusted in a graphite crucible, whereby the oxygen content can be determined.

[0016] The copper-based alloy particles contain a low amount of NiO, and the inventors have found through their investigations that this makes it possible to suppress the amount of dross (molten slag) that is generated when the copper-based alloy powder is melted. Ideally, copper-based alloy particles would be free of NiO. However, in reality, nickel is oxidized and NiO is inevitably produced during the production process of copper-based alloy particles. When copper-based alloy particles containing NiO are melted, dross due to NiO may be produced in the molten liquid. The production of dross is one factor that reduces the productivity of copper-based alloy particles. In contrast, according to the present invention, it is possible to reduce the amount of dross produced when copper-based alloy powder is melted, thereby increasing the productivity of copper-based alloy particles.

[0017] The amount of NiO contained in copper-based alloy particles can be evaluated by the abundance of NiO segregated particles. In this specification, the abundance of NiO segregated particles refers to the percentage (number %) of particles in which, when cross-sectionally observed, the area ratio of NiO present inside the particles is 2% or more among the copper-based alloy particles contained in the copper-based alloy powder. In the copper-based alloy powder of the present invention, in order to effectively suppress the generation of dross, the abundance of NiO segregated particles is preferably 4.0% by number or less, more preferably 3.0% by number or less, even more preferably 2.0% by number or less, and particularly preferably 1.0% by number or less. The smaller the abundance ratio of NiO segregated particles, the more preferable it is from the viewpoint of suppressing the generation of dross, and it is most preferably zero.

[0018] The reason why the area ratio of NiO is set to 2% or more in the definition of the abundance ratio of NiO segregated particles in the present invention is that it has been found that the generation of dross can be effectively suppressed by adopting this area ratio value. During the production process and / or storage of copper-based alloy particles, the surface of the particles may inevitably be oxidized to form oxides. These oxides may contain NiO. However, in the present invention, NiO present on the surface of the particles is not included in the calculation of the above-mentioned abundance ratio of NiO-segregated particles. In the present invention, only NiO present inside the particles is included in the calculation of the abundance ratio of NiO-segregated particles. The reason for including only NiO present inside the particles in the calculation of the abundance ratio of NiO-segregated particles is that while NiO present on the surface of particles can be removed by various reduction treatments, NiO present inside the particles is extremely difficult or impossible to remove, and therefore essentially causes the generation of dross. The presence of NiO inside the particles is particularly pronounced in atomized powders, which are powders produced by atomization.

[0019] In the copper-based alloy powder of the present invention, the average area ratio calculated for particles having an area ratio of 2% or more is preferably 30% or less, more preferably 20% or less, and even more preferably 12% or less. By setting the average value to the above-mentioned value or less, the amount of dross generated when the copper-based alloy powder is melted can be further reduced. From this perspective, the smaller the average value, the better.

[0020] Whether NiO is observed in the cross section of a copper-based alloy particle can be determined by image analysis using a scanning electron microscope-energy dispersive X-ray analysis (hereinafter also referred to as "SEM-EDX"). In an SEM image of a copper-based alloy particle obtained using SEM-EDX, regions where NiO is present appear with a contrast different from regions where NiO is not present (i.e., regions that are copper-nickel alloys). Specifically, as shown in the SEM image of the cross section of a copper-based alloy particle shown in Figure 1, regions where NiO is not present have a bright contrast, while regions where NiO is present have a dark contrast. When the image in Figure 1 is elementally mapped using SEM-EDX (not shown), it is confirmed that regions with dark contrast in the copper-based alloy particle in the figure contain higher concentrations of Ni and O than other regions in the copper-based alloy particle. Therefore, the dark contrast regions can be considered to be regions where NiO is present. Furthermore, it has been confirmed that the bright contrast regions in the copper-based alloy particles in Figure 1 contain (i) higher concentrations of Cu, (ii) lower concentrations of Ni, and (iii) similar concentrations of Cu and Ni, compared to the regions containing NiO. Therefore, the bright contrast regions can be considered to be regions containing a copper-nickel alloy. The area of ​​NiO observed on the cross section of a copper-based alloy particle can be measured using image analysis software. The specific method for measuring the area of ​​NiO is as follows.

[0021] First, a sample for EDX observation is prepared. To prepare the sample, copper-based alloy particles are embedded in resin, then a cross section is cut out and polished. Next, a metal (e.g., platinum) is sputtered onto the cross section to complete the sample preparation. This sample was observed using a scanning electron microscope (hereinafter also referred to as "SEM"). An example of an SEM image is shown in Figure 1. In the figure, the dark gray region extending along the longitudinal direction of the particle is the region where NiO segregates. The light gray region surrounding this region consists of a copper-nickel alloy. To measure the area of ​​NiO, the cross-sectional area of ​​the particle and the area of ​​the region where NiO is segregated are determined. The cross-sectional area of ​​the particle is calculated from the hatched area S2 shown in Figure 2. The area of ​​the region where NiO is segregated is the sum of the area S3 of the hatched region shown in Fig. 3 minus the area S4 of the hatched region shown in Fig. 4 (S3-S4), the area S5 of the hatched region shown in Fig. 5, and the area S6 of the hatched region shown in Fig. 6. That is, S3-S4+S5+S6. The above value is divided by the previously determined S2 and multiplied by 100, that is, (S3-S4+S5+S6) / S2×100 is calculated to calculate the area ratio of NiO. The above procedure is performed on 100 or more particles. The ratio (unit: number%) of particles with an NiO area ratio of 2% or more to the total number of particles for which the NiO area ratio has been measured is defined as the abundance ratio of segregated NiO particles.

[0022] The particle size of the copper-based alloy powder of the present invention can be adjusted appropriately depending on the application. When the copper particles of the present invention are used to form fine electrical wiring by means of, for example, screen printing, dispensing, or inkjet printing, the primary particle size is preferably set to 50 nm to 2 μm, and more preferably set to 200 nm to 1 μm. The primary particle size of the copper particles can be measured, for example, using image analysis particle size distribution measurement software MacView (manufactured by Mountec Co., Ltd.).

[0023] The copper-based alloy powder of the present invention, in the as-produced state, has a volume cumulative particle size D at 50% cumulative volume by a laser diffraction / scattering particle size distribution measurement method. 50 The volume cumulative particle diameter D of the copper-based alloy powder of the present invention is preferably 0.3 μm or more, more preferably 0.6 μm or more, and even more preferably 1.0 μm or more. 50 is preferably 15.0 μm or less, more preferably 10.0 μm or less, and even more preferably 8.0 μm or less.

[0024] The copper-based alloy powder of the present invention has a volume-cumulative particle size D at 10% by volume of the cumulative volume in the as-produced state. 10 The volume cumulative particle diameter D of the copper-based alloy powder of the present invention is preferably 0.1 μm or more, more preferably 0.3 μm or more, and even more preferably 0.5 μm or more. 10 is preferably 10.0 μm or less, more preferably 7.0 μm or less, and even more preferably 5.0 μm or less. The copper-based alloy powder of the present invention has a volume-cumulative particle size D at 90% by volume of the cumulative volume in the as-produced state. 90 The volume cumulative particle diameter D of the copper-based alloy powder of the present invention is preferably 1.0 μm or more, more preferably 2.0 μm or more, and even more preferably 2.5 μm or more. 90 is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 35 μm or less.

[0025] In the present invention, the copper-based alloy powder may be classified before use depending on the specific application of the copper-based alloy powder. Even if the copper-based alloy powder is classified, the volume-cumulative particle size D 10 , D 50 and D 90 are preferably within the above ranges.

[0026] The shape of the copper-based alloy particles constituting the copper-based alloy powder of the present invention is not particularly limited, and various shapes, such as spherical, flake, plate, and dendritic, can be used. The shape of the copper-based alloy particles to be used can be appropriately determined depending on the specific application of the copper-based alloy powder of the present invention. The shape of the copper-based alloy particles generally depends on the manufacturing method. Spherical copper-based alloy particles can be manufactured by, for example, atomization or wet reduction. Flake-shaped particles can be manufactured by, for example, mechanically plastically deforming spherical particles. The copper-based alloy powder of the present invention may also be a mixture of copper-based alloy particles of various shapes. For example, the copper-based alloy powder of the present invention may be a mixture of spherical particles and flake-shaped particles.

[0027] Next, a preferred method for producing the copper-based alloy powder of the present invention will be described. As described above, the copper-based alloy particles can be produced by, for example, atomization or wet reduction. From the viewpoint of easily producing a copper-based alloy powder in which the abundance ratio of NiO segregated particles is controlled, it is preferable to employ the atomization method.

[0028] When producing a copper-based alloy powder by atomization, a melting step is carried out before atomization to obtain a molten metal containing copper and nickel. In the melting step, copper and nickel bullion, which are the raw materials for the molten metal, are heated to a predetermined temperature in the atmosphere and melted. In addition to or instead of copper bullion or nickel bullion, a copper-nickel alloy bullion can also be used. As the copper base metal and the nickel base metal, any base metal known in the art can be used without any particular limitation. For example, electrolytic copper can be used as the copper base metal. Similarly, electrolytic nickel can be used as the nickel base metal.

[0029] In order to heat copper and nickel raw materials to obtain a molten metal, various heating furnaces can be used as heating means. Examples of heating furnaces include induction furnaces and combustion furnaces. An induction furnace is a furnace that uses electromagnetic induction to heat metals. An induction furnace has a coil that is equipped with an alternating current, which induces an electromotive force within the coil, generating eddy currents in the conductors within the coil. The Joule heat generated by these eddy currents is used to heat the metals. On the other hand, a combustion furnace uses the heat generated by burning fuels such as propane, city gas, LNG, kerosene, and heavy oil to heat the metals. The inventors' investigations have revealed that when an induction furnace is used to heat the base metal, NiO is less likely to segregate in the resulting copper-based alloy particles. This is thought to be because, when heating using an induction furnace, the molten metal flows along the magnetic field during heating, which causes the NiO to disperse into small particles and makes it less likely to segregate. In particular, when the induction furnace is lined with carbon (for example, when a graphite crucible is used in an induction furnace), the generated NiO reacts with the carbon to be reduced, resulting in a synergistic effect that makes the NiO more likely to disperse into small particles. In contrast, when heating using a combustion furnace, the molten metal does not flow actively during heating, which is thought to make NiO more likely to segregate.

[0030] When an induction furnace is used in the metal melting step, it is advantageous to obtain a molten metal by setting the output of the induction furnace to preferably 100 kW or more, more preferably 130 kW or more, and even more preferably 150 kW or more, since this further suppresses the segregation of NiO. From the viewpoints of energy saving and production efficiency, the output of the induction furnace is preferably set to 250 kW or less, more preferably 230 kW or less, and even more preferably 200 kW or less.

[0031] When obtaining molten metal using an induction furnace, it is preferable to heat to a predetermined temperature in a short time from the viewpoint of suppressing NiO segregation. From this viewpoint, it is preferable to perform the atomization method within 120 minutes, particularly within 100 minutes, and especially within 90 minutes after starting to energize the induction furnace. The shorter this time, the better from the viewpoint of suppressing NiO segregation. However, since the capacity of the induction furnace is limited, the lower limit of this time is approximately 50 minutes.

[0032] The temperature when performing the atomization method, in other words, the temperature when the metal is melted using an induction furnace, is preferably set to a relatively low temperature in order to suppress the oxidation of nickel and the segregation of NiO. From these viewpoints, the temperature when the metal is melted using an induction furnace is preferably set to 1850°C or less, more preferably 1600°C or less, and even more preferably 1500°C or less. This temperature is preferably as low as possible as long as the molten metal has sufficient fluidity. Specifically, the lower limit of the temperature is approximately 1100°C.

[0033] From the viewpoint of suppressing oxidation of nickel and suppressing segregation of NiO, it is desirable to apply as little heat as possible to nickel. From this viewpoint, when obtaining a molten metal, it is preferable to first heat and melt copper base metal, and then add and melt nickel base metal to obtain a molten metal containing copper and nickel.

[0034] When copper and nickel ingots are heated to obtain a molten metal, it is preferable to additionally add CuP (copper(I) phosphide). The addition of CuP has the advantage that phosphorus is oxidized before nickel in the molten metal is oxidized (sacrificial oxidation), thereby suppressing the formation of NiO. From this perspective, the amount of CuP added is preferably 0.007% by mass or more, more preferably 0.01% by mass or more, and even more preferably 0.02% by mass or more, calculated as elemental phosphorus relative to the molten metal after the addition of CuP. Furthermore, from the perspective of sufficiently increasing the electrical conductivity of the copper-based alloy particles, the amount of CuP added is preferably 1.0% by mass or less, more preferably 0.7% by mass or less, and even more preferably 0.5% by mass or less, calculated as elemental phosphorus relative to the molten metal after the addition of CuP. The mass of P in the copper-based alloy particles obtained after adding CuP may be smaller than the mass of P in the added CuP. This is presumably because phosphorus may sublimate during particle production (see Example 12 below). Therefore, the amount of CuP added, converted to elemental phosphorus, may differ from the phosphorus content in the copper-based alloy particles. The phosphorus content in the copper-based alloy particles is preferably 0.007% by mass or more, more preferably 0.01% by mass or more, even more preferably 0.012% by mass or more, and even more preferably 0.013% by mass or more. The phosphorus content in the copper-based alloy particles is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, and even more preferably 0.1% by mass or less.

[0035] When copper and nickel ingots are heated to obtain a molten metal, it is also preferable to additionally add a carbonaceous material. The addition of a carbonaceous material has the advantage of suppressing the formation of NiO because carbon is oxidized before nickel in the molten metal is oxidized. From this perspective, the amount of carbonaceous material added is preferably 0.5% by mass or more, more preferably 0.8% by mass or more, and even more preferably 1.0% by mass or more, based on the molten metal after the addition of the carbonaceous material. Furthermore, from the perspective of sufficiently increasing the electrical conductivity of the copper-based alloy particles, the amount of carbonaceous material added is preferably 5.0% by mass or less, more preferably 3.0% by mass or less, and even more preferably 2.0% by mass or less, based on the molten metal after the addition of the carbonaceous material.

[0036] Examples of the carbonaceous material that can be used include charcoal, activated carbon, and graphite. Other examples of the carbonaceous material include a group of carbonaceous materials known as carbon black. Specific examples include Ketjen Black (registered trademark), oil furnace black, channel black, lamp black, thermal black, and acetylene black. In the present invention, the type of carbonaceous material is not particularly limited, and any carbonaceous material can be used to suppress NiO formation.

[0037] Once the molten metal has been obtained by the above procedure, the molten metal is used in a granulation step by atomization to obtain copper-based alloy powder consisting of an aggregate of copper-based alloy particles containing copper and nickel.

[0038] As the atomization method, gas atomization and water atomization can be preferably used. Gas atomization is preferably used when uniform particle shape is desired. On the other hand, water atomization is preferably used when fine particles are desired. Of gas atomization and water atomization, high-pressure atomization is particularly preferred because it can produce fine and uniform particles. High-pressure atomization is a method of atomizing at a water pressure of about 50 MPa to 150 MPa in the case of water atomization. Gas atomization is a method of atomizing at a gas pressure of about 0.5 MPa to 3 MPa in the case of gas atomization.

[0039] Once atomized powder, i.e., copper-based alloy powder, is obtained by atomization, it may be used as is, or may be classified to obtain a powder with a specific particle size distribution. When classification is performed, it is desirable from an economical standpoint to reuse the copper-based alloy powder removed by classification. For example, the copper-based alloy powder removed by classification can be recovered and supplied to a melting process for copper and nickel metals to be used as a raw material for the molten metal described above. The copper-based alloy powder supplied to the melting process is composed of copper-based alloy particles with a low proportion of NiO segregated particles, which has the advantage of suppressing the generation of dross when the copper-based alloy powder is supplied to the melting process to obtain the molten metal.

[0040] The recovered copper-based alloy powder can be heated together with copper and nickel bullion, or alternatively, after the copper bullion is heated to obtain a molten copper metal, the nickel bullion and the recovered copper-based alloy powder can be added to the molten copper metal and melted to obtain a molten copper and nickel-containing metal.

[0041] The particles constituting the copper-based alloy powder obtained by atomization are generally spherical. The spherical copper-based alloy powder may be used as is, or may be flattened to form flakes before use. Furthermore, the spherical copper-based alloy powder may be mixed with a flaky copper-based alloy powder, or with a spherical or flaky copper powder.

[0042] The copper-based alloy powder thus obtained can be used to form fine electrical wiring by means of, for example, screen printing, dispensing, inkjet printing, etc., taking advantage of its high electrical conductivity and oxidation resistance, or can be used as an internal or external electrode of a multilayer ceramic chip capacitor. [Example]

[0043] The present invention will be described in more detail below with reference to examples. However, the scope of the present invention is not limited to such examples. Unless otherwise specified, "%" means "% by mass."

[0044] Example 1 Electrolytic copper and electrolytic nickel ingots were prepared. These ingots were used in the amounts shown in Table 1 and charged simultaneously into an induction furnace. Charcoal was also charged into the induction furnace in the amount shown in Table 1. The output of the induction furnace was set to 150 kW, and the ingots were heated in the atmosphere to obtain molten metals at the temperatures shown in Table 1. The resulting molten metal was poured into a tundish in a water atomization device. While the molten metal was falling from a nozzle at the bottom of the tundish, water was jet-sprayed onto the molten metal from the nozzle holes of a full-cone nozzle in the form of an inverted cone-shaped stream, producing atomized powder consisting of an aggregate of spherical particles. The time from the start of heating to the start of atomization was as shown in Table 1. The atomized powder thus obtained was classified using a classifier to obtain the desired copper-based alloy powder.

[0045] Examples 2 to 7 A copper-based alloy powder was obtained in the same manner as in Example 1, except that the conditions for obtaining the molten metal were as shown in Table 1.

[0046] Example 8 Instead of electrolytic nickel base metal, copper-nickel alloy base metal (copper:nickel=85%:15%) was used. The conditions for obtaining the molten metal were as shown in Table 1. Except for these, a copper-based alloy powder was obtained in the same manner as in Example 1.

[0047] Examples 9 and 10 After melting electrolytic copper to obtain a molten copper metal, electrolytic nickel was added and melted to obtain a molten copper metal containing copper and nickel. The conditions for obtaining the molten metal were as shown in Table 1. Except for these, a copper-based alloy powder was obtained in the same manner as in Example 1.

[0048] Example 11 In addition to electrolytic copper and electrolytic nickel base metals, copper-nickel alloy powder was used. The amounts used were as shown in Table 1. This copper-nickel alloy powder was the atomized powder obtained in Example 1 that had been removed by classification. After electrolytic copper ingot was melted to obtain a molten copper, electrolytic nickel ingot and copper-nickel alloy powder were added and melted to obtain a molten copper containing copper and nickel. The conditions for obtaining the molten metal are shown in Table 1. Other than these, the copper-based alloy powder was obtained in the same manner as in Example 1.

[0049] Example 12 In Example 11, electrolytic copper was melted to obtain a molten copper metal, and then electrolytic nickel, copper-nickel alloy powder, and CuP were added and melted to obtain a molten copper and nickel metal. The amount of CuP added was set to 0.03 mass % in terms of elemental phosphorus in the molten metal. The conditions for obtaining the molten metal are shown in Table 1. Other than these, the copper-based alloy powder was obtained in the same manner as in Example 11.

[0050] Examples 13 to 17 A copper-based alloy powder was obtained in the same manner as in Example 1, except that the conditions for obtaining the molten metal were as shown in Table 1. Note that, although Example 13 was produced under the same production conditions as Example 2, the particle size distribution of the obtained copper-based alloy powder differed from that of Example 2 due to the difference in the atomization batch.

[0051] Comparative Example 1 Electrolytic copper and electrolytic nickel ingots were prepared. These ingots were used in the amounts shown in Table 1 and simultaneously charged into a combustion furnace fueled by propane. Charcoal was also charged into the combustion furnace in the amount shown in Table 1. The ingots were heated to obtain molten metals at the temperatures shown in Table 1. The resulting molten metal was subjected to water atomization to produce atomized powder under the same conditions as in Example 1. The time from the start of heating to the start of atomization was as shown in Table 1. The atomized powder thus obtained was classified under the same conditions as in Example 1 to obtain the desired copper-based alloy powder.

[0052] Comparative Example 2 In addition to electrolytic copper and electrolytic nickel base metals, copper-nickel alloy powder was used. The amounts used were as shown in Table 1. This copper-nickel alloy powder was the atomized powder obtained in Example 1 that had been removed by classification. The conditions for obtaining the molten metal are shown in Table 1. Other than these, the copper-based alloy powder was obtained in the same manner as in Example 1.

[0053] Comparative Example 3 In Comparative Example 2, the amount of charcoal used was as shown in Table 1. Other than this, a copper-based alloy powder was obtained in the same manner as in Example 11.

[0054] [Table 1]

[0055] 〔evaluation〕 The copper-based alloy powders obtained in the examples and comparative examples were measured for the abundance of NiO segregated particles using the method described above. The particle size distribution was also measured using the following method. Furthermore, the copper-based alloy powders were subjected to elemental analysis and measurement of the amount of dross generated using the following methods. The results are shown in Table 2.

[0056] [Particle size distribution] 0.1 g of the measurement sample was mixed with 100 ml of a 20 mg / L aqueous solution of sodium hexametaphosphate and dispersed for 10 minutes using an ultrasonic homogenizer (US-300T manufactured by Nippon Seiki Seisakusho Co., Ltd.). The particle size distribution was then measured using a laser diffraction / scattering particle size distribution analyzer (Microtrac MT3300EX-II manufactured by Nikkiso Co., Ltd.). The volume cumulative particle size D at 10% by volume of the cumulative volume was calculated. 10 , cumulative particle size at 50% by volume D 50 , and the volume cumulative particle size at 90% by volume D 90 asked for.

[0057] [Elemental analysis] The proportions of copper, nickel and phosphorus were measured by ICP atomic emission spectrometry on a sample solution obtained by dissolving copper-based alloy particles in an acid such as hydrochloric acid. The oxygen content of the copper-based alloy particles was measured as follows: 1 g of copper-based alloy powder was weighed, placed in a nickel capsule, and then burned in a graphite crucible. The oxygen content was determined using an oxygen / nitrogen analyzer (EMGA-920, manufactured by Horiba, Ltd.).

[0058] [Amount of dross generated] After melting and atomization, the residues in the induction furnace and tundish were collected and weighed.

[0059] [Table 2]

[0060] As is clear from the results shown in Table 2, the copper-based alloy powders obtained in each example had a low NiO segregation particle content and a low amount of dross. In particular, it was found that the NiO segregation particle content was low when a molten metal was used in which nickel was added after melting copper. Furthermore, it was found that the shorter the time between the start of current application to the induction furnace and the start of atomization, the lower the NiO segregation particle content. Furthermore, it was found that the addition of Cu3P to the molten metal resulted in a lower NiO segregation particle content compared to when Cu3P was not added. Figure 7 shows a graph of the relationship between the temperature of the molten metal used in the examples and comparative examples and the abundance ratio of segregated NiO particles in the copper-based alloy powder. As is clear from the graph, the abundance ratio of segregated NiO particles is suppressed even when atomization is performed at a high molten metal temperature. It is also clear that the lower the molten metal temperature, the lower the abundance ratio of segregated NiO particles tends to be. [Industrial Applicability]

[0061] According to the present invention, there are provided a copper-based alloy powder that can suppress the generation of dross when melted, and a method for producing the same.

Claims

1. A copper-based alloy powder comprising an aggregate of copper-based alloy particles containing copper and nickel, with the remainder being unavoidable impurities, The nickel content is 5.0% by mass or more and 20.0% by mass or less, The copper content is 80.0% by mass or more and 95.0% by mass or less, a NiO segregation particle abundance rate, which is the number ratio of particles having an NiO area rate of 2% or more when observed in cross section, among the copper-based alloy particles contained in the copper-based alloy powder, of 4.0% or less.

2. A copper-based alloy powder comprising an aggregate of copper-based alloy particles containing copper, nickel, and phosphorus, with the balance being unavoidable impurities, The nickel content is 5.0% by mass or more and 15.0% by mass or less, The copper content is 80.0% by mass or more and 92.0% by mass or less, The phosphorus content is 0.007% by mass or more and 0.5% by mass or less, a NiO segregation particle abundance rate, which is the number ratio of particles having an NiO area rate of 2% or more when observed in cross section, among the copper-based alloy particles contained in the copper-based alloy powder, of 4.0% or less.

3. 3. The copper-based alloy powder according to claim 1, wherein an average of the area ratios calculated for the particles having an area ratio of 2% or more is 30% or less.

4. 3. The copper-based alloy powder according to claim 1, which is an atomized powder.

5. a melting step for obtaining a molten metal containing copper and nickel; a granulation step of using the molten metal by atomization to obtain a copper-based alloy powder comprising an aggregate of copper-based alloy particles, the copper content being 80.0% by mass or more and 95.0% by mass or less, a nickel content being 5.0% by mass or more and 20.0% by mass or less, and the balance being unavoidable impurities, A method for producing a copper-based alloy powder, wherein a carbonaceous material is added in the melting step, and the molten metal is obtained using an induction furnace with an output of the induction furnace set to 100 kW or more.

6. The method according to claim 5, wherein the melting in the induction furnace is carried out at 1850°C or less.

7. The method according to claim 5 or 6, wherein the atomization is carried out within 120 minutes after starting to energize the induction furnace.

8. A method for adding Cu to a molten metal containing copper and nickel. ３ a melting step of adding P to obtain a molten metal; and a granulation step of using the molten metal by atomization to obtain a copper-based alloy powder comprising an aggregate of copper-based alloy particles containing copper, nickel, and phosphorus, the copper content being 80.0% by mass or more and 92.0% by mass or less, a nickel content being 5.0% by mass or more and 15.0% by mass or less, and a phosphorus content being 0.007% by mass or more and 0.5% by mass or less, with the remainder being unavoidable impurities, Cu ３ The amount of P added is ３ The content of phosphorus in the molten metal after adding P is 0.005% by mass or more and 1.0% by mass or less in terms of phosphorus element, A method for producing a copper-based alloy powder, wherein a carbonaceous material is added in the melting step, and the molten metal is obtained using an induction furnace with an output of the induction furnace set to 100 kW or more.

9. The method according to claim 5 or 6, wherein in the melting step, nickel is added and melted after copper is melted.

10. 7. The manufacturing method according to claim 5, wherein the copper-based alloy powder obtained in the granulating step is classified, and the powder removed by the classification is supplied to the melting step.

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