Copper alloy powder and laminated object

Abstract

To provide a copper alloy powder that has excellent oxidation resistance and can produce an additive-manufactured article particularly suitable for metal AM (Additive Manufacturing).SOLUTION: A copper alloy powder comprises a copper alloy containing Mn of 3 mass% or more and 50 mass% or less. In the copper alloy powder, the Cu content is preferably 45 mass% or more. The total content of one or more selected from Sn, In, and Ni may be 1 mass% or more and 40 mass% or less. The total content of one or more selected from Si, Al, and Ti may be 0.5 mass% or more and 10 mass% or less. The total content of one or more selected from Zn and P may be 10 mass% or less.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a copper alloy powder and a laminated object using the copper alloy powder.

Background Art

[0002] In recent years, while attention has been focused on the antibacterial action of copper and copper alloys, in order to facilitate the shaping of products having various three-dimensional shapes and the coating of existing parts, the application of copper and copper alloys having antibacterial action to metal AM (Additive Manufactuaring) has been expected. Among this metal AM, the SLM (Selective Laser Melting) method using a laser is widely used.

[0003] For example, a laminated object by metal AM is created using a copper alloy powder having either chromium or silicon as disclosed in Patent Document 1 below, or a copper alloy powder having Cr and Zr as disclosed in Patent Document 2. Techniques are known.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, the laminated objects according to the techniques described in Patent Document 1 and Patent Document 2 do not contain elements for improving the oxidation resistance of copper. For this reason, for example, when used as a doorknob for which antibacterial action is required, there is a problem that the doorknob easily discolors due to the oxidation reaction during laminated shaping, the reaction with the atmosphere, or the contact with the sebum and moisture of the user.

[0006] Furthermore, in the case of copper alloy powder that is prone to oxidation, there is a concern that discoloration (oxide film formation) of the powder itself may occur due to reaction with the atmosphere or the like. At that time, when performing laser melting type additive manufacturing, the laser absorptivity varies among the powders depending on the presence, form, and thickness of the oxide film, and there is a problem that the melting behavior is not stable and a shaped article of stable quality cannot be obtained. Also, in the powder bed fusion (PBF) method, when the oxidation resistance of the copper alloy powder is low, there is a problem that the unmelted copper alloy powder also reacts with the atmosphere and oxidizes due to heat transfer from the melted part, which is one of the factors reducing the recyclability of the unmelted powder.

[0007] Therefore, in the case of copper alloy powder, it is required from the viewpoints of stabilizing the melting behavior by laser in laser melting type additive manufacturing and improving the recyclability of the powder that the powder has excellent oxidation resistance, that is, the state of the surface oxidation product film is stable.

[0008] The present invention was devised in view of the above problems, and an object thereof is to provide a copper alloy powder having excellent oxidation resistance and capable of manufacturing a shaped article particularly suitable for metal AM, and a shaped article formed of this copper alloy powder.

Means for Solving the Problems

[0009] In order to achieve the above object, the copper alloy powder of the present invention A copper alloy powder for laminated forming, contains Mn in the range of 3 mass% or more and 50 mass% or less which is composed of a copper alloy having a composition of the balance Cu and inevitable impurities, has a volume average particle size of 10 μm or more and 150 μm or less, a ratio Da / Dt of the powder loose bulk density Da to the powder true density Dt is 0.4 or more, integral intensity values are obtained for the peaks of Cu and O in the XPS analysis of the powder surface, and the abundance ratio Cu / O of Cu and O obtained by performing concentration conversion by the relative sensitivity coefficient method is 0.1 or more. Among the peaks of Cu in the XPS analysis of the powder surface, the Cu2p3 / 2 peak is separated into two peaks at 933.7 eV derived from CuO and 932.5 - 932.7 eV derived from Cu or Cu 2 O, the ratio of the integral intensity values of each peak is taken as the abundance ratio of each, and the ratio of CuO in the peaks of Cu is taken as the value of CuO / (Cu + Cu 2 O + CuO), and the ratio (Cu + Cu 2 O) / CuO of the total of Cu and Cu 2 O to CuO is 1 or more 2 Furthermore, and is characterized by this.

[0010] According to the copper alloy powder of the present invention, by containing an appropriate amount of Mn, a copper alloy powder excellent in oxidation resistance can be provided. Further, since it does not easily discolor, it is difficult to cause fluctuations in laser absorptivity during laser irradiation when forming a laminated object. For this reason, with the irradiation of the laser, heat generation can be obtained in a stable state, and a laminated object can be manufactured in a state where the melting behavior is stable. That is, the copper alloy powder containing Mn in the above range has a small change rate of the laser absorption rate and is desirable for applications such as laminated molding. In addition, when the laminated object is something that comes into contact with the user's hand or something visible to the user's eyes, if there is a discolored phase generated due to the oxidation reaction of Cu on the surface, the design property will be significantly reduced, and depending on the degree of oxidation, the touch feeling will also be reduced. Therefore, it is desirable to contain Mn in the above range.

[0011] Here, in the copper alloy powder of the present invention, it is preferable to contain 45% by mass or more of the Cu. In this case, by containing 45% by mass or more of Cu, a copper alloy powder excellent in antibacterial property can be provided. Further, when it is made into a laminated object, it becomes possible to expose a phase containing a sufficient amount of Cu on the surface of the laminated object, and a laminated object excellent in antibacterial property can be provided by the antibacterial action inherent in Cu.

[0012] In the copper alloy powder of the present invention, even if it contains one or more selected from Sn, In, Ni in total within the range of 1% by mass or more and 40% by mass or less even if it contains is good. Elements such as Sn, In, and Ni have low oxidizability and a relatively wide solid solution range with respect to Cu. Therefore, a relatively large amount can be contained as a replacement for Cu, ensuring the oxidation resistance of the copper alloy powder and reducing the change rate of the laser absorption rate.

[0013] Furthermore, in the copper alloy powder of the present invention, Furthermore, one or more selected from Si, Al, Ti in total may be contained within the range of 0.5% by mass or more and 10% by mass or less. Si, Al, and Ti are highly oxidizing, and a thin and strong oxide film is formed on the surface of the copper alloy powder. Therefore, during additive manufacturing or use, further oxidation is suppressed, and the oxidation resistance is improved. As a result, the laser absorption rate is stabilized, and discoloration during use can be suppressed. In addition, by setting the total content of one or more selected from Si, Al, and Ti to 10% by mass or less, it is possible to suppress the formation of an oxide film that is thicker than necessary, and the antibacterial property of copper in the copper alloy powder and the additive manufactured object can be ensured.

[0014] In addition, in the copper alloy powder of the present invention, Furthermore, One or two selected from Zn and P in total 10% by mass or less even if it contains is good. Zn and P are elements that dissolve in Cu in a wide range and can improve the discoloration resistance. In addition, since they are cheaper than copper, the cost can be reduced. However, they have a high vapor pressure, and a large amount of fumes are generated during powder production or laser irradiation, which has an adverse effect on productivity. Therefore, the total content of one or two selected from Zn and P is preferably 10% by mass or less. In addition, since P has the effect of deoxidizing the copper alloy by binding to the contained oxygen, it may be contained within the above range.

[0015] Furthermore, in the copper alloy powder of the present invention, the abundance ratio Cu / O of each element determined from the peaks of Cu and O in the XPS analysis of the powder surface is preferably 0.10 or more. If the abundance ratio Cu / O of the elements determined from the peaks of Cu and O by XPS analysis is 0.10 or more, a copper alloy powder with a low degree of surface oxidation can be provided, and an additive manufactured object with a low degree of oxidation can be provided when used for additive manufacturing. In addition, the antibacterial property of the copper alloy powder and the additive manufactured object can be ensured.

[0016] In addition, in the copper alloy powder of the present invention, among the peaks of Cu in the XPS analysis of the powder surface, the ratio (Cu + Cu2O) / CuO of the total of Cu and Cu2O (Cu + Cu2O) to CuO is preferably 1 or more. Among the Cu peaks obtained by XPS analysis, if (Cu + Cu2O) / CuO is 1 or more, it is possible to provide a copper alloy powder with a low degree of surface oxidation, and when used for additive manufacturing, it is possible to provide an additive manufactured object with a low degree of oxidation. In addition, the antibacterial properties of the copper alloy powder and the additive manufactured object can be ensured.

[0017] Furthermore, in the copper alloy powder of the present invention, it is preferable that the ratio of CuO among the Cu peaks in the XPS analysis of the powder surface is 40% or less. Among the Cu peaks obtained by XPS analysis, if the ratio of CuO is 40% or less, it is possible to provide a copper alloy powder with a low proportion of surface oxidation, and when used for additive manufacturing, it is possible to provide an additive manufactured object with a low proportion of oxidation. In addition, the antibacterial properties of the copper alloy powder and the additive manufactured object can be ensured.

[0018] Also, in the copper alloy powder of the present invention, it is preferable that the thickness of the surface oxidation product film formed on the surface is 3 μm or less. If the thickness of the surface oxidation product film is 3 μm or less, the antibacterial property of the copper alloy powder can be ensured, and since the thickness of the surface oxidation product film is small, when used for additive manufacturing, it is possible to provide an additive manufactured object with a low proportion of oxides. Note that the thickness of the surface oxidation product film can be confirmed by processing the cross-section of the powder for observation using the FIB (Focused Ion Beam) method and then observing the cross-section with SEM. By using EDS (Energy Dispersive X-ray Spectroscopy) to measure the peak derived from O (oxygen) in the depth direction, the depth until the O concentration (oxygen concentration) becomes 0.5 at% or less can be taken as the thickness of the surface oxidation product film.

[0019] Furthermore, in the copper alloy powder of the present invention, it is preferable that the volume average particle size is 10 μm or more and 150 μm or less. If the volume average particle size is within the above range, when used for additive manufacturing, powder aggregation is less likely to occur, and a decrease in fluidity is less likely to occur. Also, since the powder particle size is an appropriate size, uniform powder layering is possible, and no molding defects occur.

[0020] Further, in the copper alloy powder of the present invention, the ratio Da / Dt of the powder apparent density Da to the powder true density Dt is preferably 0.4 or more. By setting Da / Dt to 0.4 or more, the voids during powder lamination can be reduced, and a decrease in the density of the laminated object can be prevented after melting by laser.

[0022] Also, the copper alloy powder of the present invention preferably has antibacterial properties. Since the copper alloy powder has antibacterial properties, it becomes possible to configure various members that require antibacterial properties using this copper alloy powder.

[0023] A laminated object according to one embodiment of the present invention is characterized by being formed using the above-described copper alloy powder. According to the laminated object of the present invention, since it is formed of a copper alloy powder having excellent oxidation resistance as described above, the variation in laser absorptivity during laser irradiation when forming the laminated object is small, and the quality is excellent.

Effects of the Invention

[0024] According to the present invention, it is possible to provide a copper alloy powder having excellent discoloration resistance and particularly suitable for metal AM, and a laminated object formed of this copper alloy powder.

Brief Description of the Drawings

[0025]

Figure 1

Modes for Carrying Out the Invention

[0026] The present invention will be described in detail below, but the present invention is not limited to the embodiments described below. FIG. 1 is a side view showing a part of the copper alloy powder for laminated manufacturing according to one embodiment of the present invention, with a part broken away.

[0027] The copper alloy powder 1 of this embodiment has a powder body 2 made of a copper alloy and a surface oxide product film 3 formed on the outer peripheral surface of this powder body 2. The copper alloy powder 1 of this embodiment has, as an example, a powder body 2 having a spherical shape or a shape similar thereto and a surface oxide product film 3 thinly covering the entire outer peripheral surface thereof. Regarding the surface oxide product film 3, a structure without it is desirable, but if it is formed, it is preferably as thin as possible, and preferably within the film thickness range described later.

[0028] The powder body 2 is made of a copper alloy containing 3 mass% or more and 50 mass% or less of Mn. As an example, it may be a copper alloy containing 3 mass% or more and 50 mass% or less of Mn and having a composition of the balance Cu and inevitable impurities. Here, in the copper alloy powder 1 of this embodiment, the copper alloy constituting the powder body 2 preferably contains 45 mass% or more of Cu.

[0029] Also, in the copper alloy powder 1 of this embodiment, the copper alloy constituting the powder body 2 may have a total content of one or more selected from Sn, In, and Ni in the range of 1 mass% or more and 40 mass% or less. Furthermore, in the copper alloy powder 1 of this embodiment, the copper alloy constituting the powder body 2 may have a total content of one or more selected from Si, Al, and Ti in the range of 0.5 mass% or more and 10 mass% or less. Also, in the copper alloy powder 1 of this embodiment, the copper alloy constituting the powder body 2 may have a total content of one or two selected from Zn and P of 10 mass% or less.

[0030] Furthermore, in the copper alloy powder 1 of this embodiment, the abundance ratio Cu / O of each element determined from the peaks of Cu and O in the XPS analysis of the powder surface is preferably 0.10 or more. Also, in the copper alloy powder 1 of this embodiment, the ratio of CuO among the peaks of Cu in the XPS analysis of the powder surface is preferably 40% or less. Furthermore, in the copper alloy powder 1 of the present embodiment, it is preferable that the thickness of the surface oxide product film formed on the surface is 3 μm or less.

[0031] Also, in the copper alloy powder 1 of the present embodiment, it is preferable that the volume average particle diameter is 10 μm or more and 150 μm or less. Furthermore, in the copper alloy powder 1 of the present embodiment, it is preferable that the ratio Da / Dt of the powder loose bulk density Da to the powder true density Dt is 0.4 or more.

[0032] Next, regarding the composition of the copper alloy powder 1 according to the present embodiment, the XPS analysis of the surface, the thickness of the surface oxide product film, the volume average particle diameter, and the ratio Da / Dt of the powder loose bulk density Da to the powder true density Dt, the reasons defined as above will be explained.

[0033] (Mn: 3 mass% or more and 50 mass% or less) Mn is an element that contributes to the improvement of the oxidation resistance of the copper alloy powder 1 when it is contained in Cu to form a copper alloy. By containing an appropriate amount of Mn within the above range, a copper alloy powder with excellent oxidation resistance can be provided. Also, since it does not easily discolor, it is less likely to cause fluctuations in laser absorptivity during laser irradiation when forming a laminated object. Therefore, with laser irradiation, heat generation can be obtained in a stable state, and a laminated object can be manufactured in a state with stable melting behavior. Also, it can be seen that the copper alloy powder containing Mn within the above range is desirable for applications such as laminated manufacturing because the change rate of the laser absorption rate after the heat resistance test is small.

[0034] Also, when the laminated object formed by the copper alloy powder 1 is something that comes into contact with the user's hand and something visible to the user's eyes, if there is a discolored phase generated due to the oxidation reaction of Cu on the surface, the design property will be significantly reduced, and depending on the degree of oxidation, the touch feel will also decrease. Therefore, it is desirable to contain Mn within the above range. Also, if the concentration of Mn is too high, there is a possibility that the antibacterial property of the powder will decrease. Incidentally, the content of Mn is preferably 5% by mass or more, more preferably 10% by mass or more. Also, the content of Mn is preferably 45% by mass or less, more preferably 40% by mass or less.

[0035] (Cu: 45% by mass or more) Cu is the main component, and in order to ensure the antibacterial property of the copper alloy powder 1, it is preferably contained in an amount of 45% by mass or more. By containing Cu in an amount of 45% by mass or more, a copper alloy powder excellent in antibacterial property can be provided. Also, when it is a laminated object, a phase containing a sufficient amount of Cu can be exposed on the surface of the laminated object, and a laminated object excellent in antibacterial property can be provided by the antibacterial action inherent in Cu. Incidentally, the content of Cu is more preferably 50% by mass or more, even more preferably 55% by mass or more. Although there is no particular limitation on the content of Cu, it is preferably 97% by mass or less, more preferably 95% by mass or less.

[0036] (Total content of Sn, In, Ni: 1% by mass or more and 40% by mass or less) Since the elements of Sn, In, and Ni have low oxidizability and a relatively wide solid solution range with respect to Cu, a relatively large amount of Sn, In, and Ni can be contained as a replacement for Cu, ensuring the oxidation resistance of the copper alloy powder and reducing the change rate of the laser absorption rate. Therefore, when aiming to improve the oxidation resistance and laser absorption stability of the copper alloy powder 1, it is desirable to contain Sn, In, and Ni in a total amount in the range of 1% by mass or more and 40% by mass or less. Incidentally, the total content of Sn, In, and Ni is more preferably 1.5% by mass or more, even more preferably 2.0% by mass or more. Although there is no particular limitation on the total content of Sn, In, and Ni, it is preferably 37% by mass or less, more preferably 35% by mass or less.

[0037] (Total content of Si, Al, Ti: 0.5% by mass or more and 10% by mass or less) Si, Al, and Ti are elements that are soluble in Cu over a wide range together with Mn. Even when added within the above-mentioned range, they do not impair the antibacterial property inherent in Cu, nor do they impair the oxidation resistance obtained by containing Mn within the above-mentioned range. Also, Si, Al, and Ti have high oxidizing properties, and a thin and strong oxide film is formed on the surface of the copper alloy powder. Therefore, during additive manufacturing or use, further oxidation is suppressed, and the oxidation resistance is improved. As a result, the laser absorption rate is stabilized, and discoloration during use can be suppressed. Note that if the content of Si, Al, and Ti is too high, there is a risk that the oxide film will be formed thicker than necessary. Therefore, it is preferable that the total content of Si, Al, and Ti is in the range of 0.5% by mass or more and 10% by mass or less. In addition, the total content of Si, Al, and Ti is more preferably 1.0% by mass or more, and even more preferably 1.5% by mass or more. Although there is no particular limitation on the total content of Si, Al, and Ti, it is preferably 9% by mass or less, and more preferably 8% by mass or less.

[0038] (Total content of Zn and P: 10% by mass or less) Zn and P are elements that are soluble in Cu over a wide range and can improve the discoloration resistance. Also, since they are less expensive than copper, the cost can be reduced. However, they have a high vapor pressure, and a large amount of fumes are generated during powder production or laser irradiation, which has an adverse effect on productivity. Note that P has the effect of deoxidizing the copper alloy by binding to the contained oxygen. In this embodiment, when Zn or P is included, it is preferably 10% by mass or less. In addition, the total content of Zn and P is preferably 8% by mass or less, and more preferably 7% by mass or less.

[0039] (Other elements) In the copper alloy powder 1 of the present embodiment, as other elements, one or more selected from C, N, Sc, V, Sr, H, Li, B, O, Mg, S, Ca, Cr, Fe, Co, Ga, Ge, Se, Y, Zr, Nb, Mo, Ag, Sb, Te, Ba, Ce, La, Hf, Ta, Pb, Bi may be contained in a total amount of 0.1% by mass or more and 10% by mass or less. Also, the other elements may be contained as impurities in an amount of about 0.1% by mass or less. When manufacturing the alloy of this embodiment from melting, elements such as Ag and S that may be unavoidably mixed as impurities in the raw materials may be contained as impurities within the above range. Of course, other impurity elements may be contained within the above range.

[0040] (XPS analysis of the surface) In the copper alloy powder 1 of the present embodiment, as a result of XPS analysis of the surface (XPS analysis of the surface oxide product film 3), when the abundance ratio Cu / O of each element determined from the peaks of Cu and O is 0.10 or more, a copper alloy powder with a low surface oxidation rate can be provided, and when used for additive manufacturing, an additive manufactured object with a low oxidation rate can be provided. Note that the abundance ratio Cu / O of each element determined from the peaks of Cu and O is more preferably 0.15 or more, and even more preferably 0.20 or more. There is no particular limitation on the upper limit of the abundance ratio Cu / O, but it is preferably 0.9 or less, and more preferably 0.8 or less.

[0041] Also, in the copper alloy powder 1 of the present embodiment, as a result of XPS analysis of the surface (XPS analysis of the surface oxide product film 3), when the ratio (Cu + Cu2O) / CuO of the sum of Cu and Cu2O (Cu + Cu2O) to CuO among the peaks of Cu is 1 or more, the ratio of CuO on the surface is small, a copper alloy powder with a low degree of surface oxidation can be provided, and when used for additive manufacturing, an additive manufactured object with a low degree of oxidation can be provided, and an additive manufactured object with excellent antibacterial properties can be provided. In addition, the ratio of the total of Cu and Cu2O (Cu + Cu2O) to CuO, (Cu + Cu2O) / CuO, is more preferably 1.5 or more, and even more preferably 2.0 or more. There is no particular limitation on the upper limit of (Cu + Cu2O) / CuO, but it is preferably 20 or less, and more preferably 15 or less.

[0042] Furthermore, in the copper alloy powder 1 of the present embodiment, as a result of XPS analysis of the surface (XPS analysis of the surface oxide product film 3), when the ratio of CuO among the peaks of Cu is 40% or less, the ratio of CuO on the surface is small, and when used for additive manufacturing applications, it is possible to provide an additive manufactured object with excellent antibacterial properties. In addition, the ratio of CuO among the peaks of Cu is more preferably 35% or less, and even more preferably 30% or less. There is no particular limitation on the lower limit of the ratio of CuO among the peaks of Cu, but it is preferably 1% or more, and more preferably 2.5% or more.

[0043] (Thickness of the surface oxide product film: 3 μm or less) In the copper alloy powder 1 of the present embodiment, if the thickness of the surface oxide product film 3 formed on the surface becomes large, there is a risk that antibacterial properties cannot be ensured. Therefore, in order to ensure antibacterial properties, it is preferable that the thickness of the surface oxide product film 3 is 3 μm or less. In addition, the thickness of the surface oxide product film 3 is more preferably 2.0 μm or less, even more preferably 1.5 μm or less, and furthermore, the surface oxide product film 3 may not exist.

[0044] (Volume average particle size) In the copper alloy powder 1 of the present embodiment, when used for additive manufacturing applications, it is preferable that the volume average particle size is in the range of 10 μm or more and 150 μm or less. When the volume average particle size of the copper alloy powder 1 is 10 μm or more, it is possible to suppress a decrease in fluidity due to powder aggregation. Also, when the volume average particle size of the copper alloy powder 1 is 150 μm or less, uniform powder layering and supply are possible, and shaping can be performed stably. The volume average particle diameter of the more preferable copper alloy powder 1 varies depending on the additive manufacturing method and apparatus configuration. In the PBF (Powder Bed Fusion) method, it is in the range of 10 μm or more and 60 μm or less, and in the DED (Directed Energy Deposition) method, it is in the range of 50 μm or more and 150 μm or less.

[0045] (Ratio of the bulk density to the true density of the copper alloy powder) In the copper alloy powder 1 of the present embodiment, when used for additive manufacturing, the ratio Da / Dt of the powder bulk density Da to the powder true density Dt is preferably 0.4 or more. When Da / Dt of the copper alloy powder 1 is 0.4 or more, the voids during powder lamination are reduced, and the density of the additive manufactured object after laser melting can be improved. Note that Da / Dt of the copper alloy powder 1 is more preferably 0.45 or more, and even more preferably 0.50 or more.

[0046] Next, an example of the method for manufacturing the copper alloy powder 1 of the present embodiment will be described. As an example of the method for manufacturing the copper alloy powder 1 of the present embodiment, a gas atomization method known as a technique for obtaining spherical or spherical-like powders by using a copper alloy melt obtained by melting a copper alloy base material and spraying with a high-pressure gas can be adopted. As the copper alloy base material used here, a copper alloy base material having the above-described composition can be used, or a plurality of base materials can be used so that the above-described component elements have the above-described composition ratio to form an alloy melt. The alloy base material may contain inevitable impurities within the above-described range.

[0047] Also, as the high-purity copper serving as the base of the copper alloy base material, high-purity copper with a purity of 99.99 mass% or more and less than 99.9999 mass% can be used, and a copper alloy melt having the above-described composition ratio can be obtained by adding a necessary amount of elemental metal or alloy to this high-purity copper and melting it. The measurement of the content of these trace elements in the copper alloy powder 1 can be carried out by high-frequency inductively coupled plasma optical emission spectrometry or the like.

[0048] In this embodiment, an example of using the gas atomization method to describe the method for manufacturing the copper alloy powder 1 has been described. However, regarding the powder manufacturing method, in addition to this, the copper alloy powder may be manufactured by other methods such as the water atomization method, the centrifugal atomization method, the inductively coupled plasma method, or the plasma atomization method. Alternatively, other generally known methods for manufacturing powders for additive manufacturing may be applied. The copper alloy powder 1 obtained as described above may be appropriately heat-treated to achieve tissue stabilization or the like.

[0049] In order to perform flow adjustment and agglomeration separation of the copper alloy powder 1 obtained as described above, it is desirable to perform a classification step so that the volume average particle size of the copper alloy powder 1 is in the range of 10 μm or more and 150 μm or less. Sieving methods, gravity classification, centrifugal classification, etc. can be used for the classification step.

[0050] Using the copper alloy powder 1 of this embodiment obtained as described above, for example, additive manufacturing can be carried out using M280 of EOS (trade name of Electro Optical Systems (EOS) in Germany). In this additive manufactured object, if the copper alloy powder 1 with appropriate particle size and bulk density is used, an additive manufactured object with excellent forming accuracy and high density can be provided.

[0051] In addition, in the copper alloy powder 1 of this embodiment, when it contains 45 mass% or more of Cu, a copper alloy powder with excellent antibacterial properties can be provided. Also, when it is made into an additive manufactured object, it is possible to expose a phase containing a sufficient amount of Cu on the surface of the additive manufactured object, and an additive manufactured object with excellent antibacterial properties can be provided due to the antibacterial action inherent in Cu.

[0052] In addition, in the copper alloy powder 1 of this embodiment, when it contains a total of 1 mass% or more and 40 mass% or less of one or more selected from Sn, In, and Ni, a relatively large amount can be contained as a replacement for Cu, ensuring oxidation resistance and also reducing the rate of change of the laser absorption rate.

[0053] Furthermore, in the copper alloy powder 1 of the present embodiment, when one or more selected from Si, Al, and Ti are contained in a total amount of 0.5 mass% or more and 10 mass% or less, a thin and strong oxide film (surface oxidation product film 3) is formed on the surface of the copper alloy powder 1, and further oxidation during laminated manufacturing or use is suppressed, improving oxidation resistance. As a result, the laser absorption rate is stabilized and discoloration during use can be suppressed. Also, formation of an oxide film (surface oxidation product film 3) that is thicker than necessary can be suppressed, and the antibacterial property of copper can be ensured.

[0054] Also, in the copper alloy powder 1 of the present embodiment, when Zn and P are contained in a total amount of 10 mass% or less, the discoloration resistance can be improved.

[0055] Furthermore, in the copper alloy powder 1 of the present embodiment, when the abundance ratio Cu / O of each element obtained from the peaks of Cu and O in the XPS analysis of the powder surface is 0.10 or more, a copper alloy powder 1 with a low degree of surface oxidation can be provided, and when used for laminated manufacturing, a laminated product with a low degree of oxidation can be provided. Also, the antibacterial property of the copper alloy powder 1 and the laminated product can be ensured.

[0056] Also, in the copper alloy powder 1 of the present embodiment, when the ratio (Cu + Cu2O) / CuO of the total of Cu and Cu2O (Cu + Cu2O) to CuO among the peaks of Cu in the XPS analysis of the powder surface is 1 or more, a copper alloy powder 1 with a low degree of surface oxidation can be provided, and when used for laminated manufacturing, a laminated product with a low degree of oxidation can be provided. Also, the antibacterial property of the copper alloy powder 1 and the laminated product can be ensured.

[0057] Furthermore, in the copper alloy powder 1 of the present embodiment, when the ratio of CuO among the peaks of Cu in the XPS analysis of the powder surface is 40% or less, a copper alloy powder with a low rate of surface oxidation can be provided, and when used for laminated manufacturing, a laminated product with a low rate of oxidation can be provided. Also, the antibacterial property of the copper alloy powder 1 and the laminated product can be ensured.

[0058] Further, in the copper alloy powder 1 of the present embodiment, when the thickness of the surface oxide product film formed on the surface is 3 μm or less, since the thickness of the surface oxide product film is small, a laminated molded product with a small proportion of oxides can be provided when used for laminated molding applications. Further, the antibacterial properties of the copper alloy powder 1 and the laminated molded product can be ensured.

[0059] Furthermore, in the copper alloy powder 1 of the present embodiment, when the volume average particle diameter is in the range of 10 μm or more and 150 μm or less, powder aggregation hardly occurs and a decrease in fluidity hardly occurs when used for laminated molding applications. Also, since the powder particle diameter is an appropriate size, uniform powder lamination is possible and molding defects do not occur.

[0060] Also, in the copper alloy powder 1 of the present embodiment, when the ratio Da / Dt of the powder loose bulk density Da to the powder true density Dt is 0.4 or more, the voids during powder lamination can be reduced, and a decrease in the density of the laminated molded product can be prevented after melting by laser.

[0061] Furthermore, when the copper alloy powder 1 of the present embodiment is used for laminated molding, it is excellent in laser absorptivity and discoloration resistance, and a laminated molded product can be stably produced.

[0062] Also, when the copper alloy powder 1 of the present embodiment has antibacterial properties, it becomes possible to configure various members that require antibacterial properties using this copper alloy powder 1.

[0063] The laminated molded product of the present embodiment is formed using the copper alloy powder 1 of the present embodiment described above, so it is formed of the copper alloy powder 1 having excellent oxidation resistance, and there is little variation in laser absorptivity during laser irradiation when forming the laminated molded product, and it is excellent in quality.

[0064] As described above, the embodiments of the present invention have been described, but the present invention is not limited thereto, and can be appropriately modified without departing from the technical idea of the invention.

Example

[0065] The results of the verification experiments conducted to confirm the effects of the present invention will be described below.

[0066] The required amount of master alloy was added to high-purity copper with a purity of 99.999% by mass and introduced into a melting furnace to prepare a copper alloy molten metal. Each copper alloy powder was prepared from this copper alloy molten metal by the gas atomization method. Each of the obtained copper alloy powders was subjected to sieving and washing to remove fine powders consisting of coarse powders and fumes, and sieving according to the target particle size was performed as necessary to obtain copper alloy powders having the compositions shown in Table 1.

[0067] For the copper alloy powders with each composition ratio, the volume average particle size, the ratio Da / Dt of the powder loose bulk density Da to the powder true density Dt, the XPS analysis of the surface, the thickness of the surface oxide product film, and the change rate of the laser absorption rate were evaluated.

[0068] Further, using the obtained copper alloy powders, a 10 mm square cube-shaped laminated object was produced using an M280 (3D printer) manufactured by EOS. Regarding the obtained laminated object, the antibacterial property and the measurement of the discoloration resistance were determined by the methods described below.

[0069] (Volume average particle size of copper alloy powder) Using a MT3300EXII manufactured by Microtrac, the particle size distribution was measured wet, and the volume-based 50% cumulative particle size of the obtained results was taken as the volume average particle size.

[0070] (Ratio Da / Dt of powder loose bulk density Da to powder true density Dt) The loose bulk density Da of the copper alloy powder was measured using a Powder Tester PT-X manufactured by Hosokawa Micron in accordance with the Japan Powder Industry Technology Association Standard SAP05-98:2013. In calculating the loose bulk density Da of the powder, the simple average value of three measurements was used. The true density Dt of the copper alloy powder was measured by the gas displacement method using an Ultra Pycnometer 1000 type manufactured by QURNTACHROME INSTRUMENTS. The ratio Da / Dt of the apparent density Da to the true density Dt of the obtained powder was calculated from the values of the apparent density and the true density of the powder.

[0071] (XPS analysis) Among the target samples, surface analysis was performed on Invention Example 2 and Invention Example 7 of the present invention by XPS (X-ray photoelectron spectroscopy). The samples were measured after being attached to a carbon tape. The measurement results of XPS are shown in Table 2. Note that the measurement results of XPS describe the minimum value and the maximum value when measuring a plurality of samples of the same composition multiple times. Integrated intensity values were obtained for the peaks of Cu and O on the surface, respectively, concentration conversion was carried out by the relative sensitivity coefficient method, the abundance ratios of Cu and O were determined, and the ratio of Cu / O was calculated.

[0072] Regarding the ratios of Cu, Cu2O, and CuO on the surface, chemical state separation was performed using the peak of Cu to obtain them. Specifically, first, the Cu2p3 / 2 peak was separated into two peaks: 933.7 eV derived from CuO and 932.5 - 932.7 eV derived from Cu or Cu2O. Then, the ratio of the integrated intensity values of each peak was used as the abundance ratio of each. Note that since Cu and Cu2O each have a peak in the energy band of 932.5 - 932.7 eV and it is difficult to separate the peaks in principle, they were calculated as the abundance in the form of the combination of Cu and Cu2O. Also, the ratio of CuO in the peaks of Cu was taken as the value of CuO / (Cu + Cu2O + CuO).

[0073] In addition, the thickness of the surface oxide product film was confirmed by using the FIB (Focused Ion Beam) method to process a cross-section near the surface for observation and then observing the cross-section with SEM. Using EDS (Energy Dispersive X-ray Spectroscopy), the peak derived from O (oxygen) was measured, and the depth until the O concentration (oxygen concentration) became 0.5 at% or less was evaluated as the film thickness of the surface oxide product film. Note that the measurement by XPS and the thickness of the surface oxide product film by SEM-EDS were also measured for the laminated object, and it was confirmed that they were of the same order as the particles.

[0074] (Antibacterial Evaluation Method) The simple antibacterial test method used for antibacterial evaluation followed JIS Z 2801. Using the film method, bacteria were seeded on the sample, and the test was conducted on the laminated object. For the laminated object, a copper alloy powder sample was used, and a laminated object with dimensions of 50×50 mm and a thickness of 1 mm was fabricated using the EOS M280 (3D printer). The tests were carried out under the conditions of test times of 10, 20, 30, 40, 50, 60, 70, 80, 90, and 100 min. After a certain period of time elapsed, the bacteria were collected, and the viable cell count was measured. Escherichia coli (ATCC8739 strain) specified by JIS was used as the bacterial species. From the results, the time (T 1 / 10 ) when the number of bacteria became 1 / 10 was measured. The average value was obtained from the results of n5 at each measurement point, and the value was derived. T 1 / 10 If T was 10 minutes or less, the antibacterial property was evaluated as "◎"; if it exceeded 10 minutes and was 20 minutes or less, it was "○"; if it exceeded 20 minutes and was 100 minutes or less, it was "△"; if it did not become 1 / 10 at 100 minutes, it was "×". It is considered that particles with the same composition as the laminated object also have equivalent antibacterial properties.

[0075] (Discoloration Resistance Evaluation Method) For the discoloration resistance test to evaluate discoloration resistance, after polishing the surface of a 15 mm square cube-shaped laminated object made using a copper alloy powder sample and the EOS M280 (3D printer) with emery paper #1000, the polished surface was placed on top, and each sample was exposed to an atmosphere with a temperature of 60 °C and a relative humidity of 95% using a thermo-hygrostat. The test time was 144 hours. After the test, the sample was taken out, and the change in the appearance of the upper surface, which was the polished surface, was confirmed using a color difference meter. For the discoloration resistance evaluation, those with no change in appearance confirmed over the entire surface were judged as "◎", those with discoloration of the appearance occurring only in less than half of the entire surface were "○", and those with discoloration of the appearance seen over more than half of the entire surface were judged as "×", as described in Table 1. The discoloration of the appearance referred to here was based on a color difference ΔE of 10 or more shown by the color difference measured in accordance with JIS 8781-4 using the SCI (including regular reflection light) method with the spectrophotometer "CM-700d" manufactured by Konica Minolta.

[0076] (Rate of change of laser absorption rate) For each sample, using the ultraviolet-visible near-infrared spectrophotometer "UH4150" manufactured by Hitachi High-Tech Science Corporation, the rate of change of the laser absorption rate before and after the durability test for light with a wavelength of 1064 nm was determined. The absorption rate was calculated as "absorption rate = 1 - total reflectance". The durability test is to perform a test of heating to 200 °C in an air atmosphere and holding for 60 minutes. When the absolute value of the rate of change of the laser absorption rate before and after the durability test was less than 20%, it was evaluated as "◎", when it was 20% or more and less than 50%, it was evaluated as "〇", and when it was 50% or more, it was evaluated as "×". For example, when the laser absorption rate before the durability test was 50% and the laser absorption rate after the durability test was 55%, the absolute value of the rate of change of the laser absorption rate was (55 - 50) / 50 = 10%.

[0077]

Table 1

[0078]

Table 2

[0079] In Comparative Example 1 of pure copper powder, although it was excellent in antibacterial properties, it was inferior in discoloration resistance. In Comparative Example 2 in which the Mn content was 75% by mass, it was excellent in discoloration resistance, but the antibacterial property was insufficient. In Comparative Example 3 in which the copper content was 5% by mass and the Mn content was 82% by mass, it was excellent in discoloration resistance, but the antibacterial property was insufficient.

[0080] In contrast, Examples 1 to 21 of the present invention were excellent in discoloration resistance and had a small rate of change of the laser absorption rate. They were also excellent in antibacterial properties. In Examples 1 to 21 of the present invention, the ratio of the powder looseness bulk density Da to the powder true density Dt, Da / Dt, was 0.4 or more. From these results, it is clear that the copper alloy powder according to the present invention can provide a copper alloy powder that is excellent in discoloration resistance and antibacterial properties and has little change in laser absorption rate after heating at 200°C.

[0081] Also, as shown in Table 2, in Examples 2 and 7 of the present invention, the abundance ratio Cu / O of each element determined from the peaks of Cu and O in the XPS analysis was 0.10 or more, specifically 0.10 to 0.45. As shown in Table 2, in Examples 2 and 7 of the present invention, among the peaks of Cu in the XPS analysis, the ratio (Cu + Cu2O) / CuO of the total of Cu and Cu2O (Cu + Cu2O) to CuO was 1 or more, specifically 1.5 to 7.5. As shown in Table 2, in Examples 2 and 7 of the present invention, the ratio of CuO among the peaks of Cu in the XPS analysis was 40% or less, specifically 12 to 40%. As shown in Table 2, in Examples 2 and 7 of the present invention, the thickness of the surface oxide product film was 0.7 μm and 1.6 μm.

Explanation of Reference Numerals

[0082] 1 Copper alloy powder 2 Powder body 3 Surface oxide product film.

Claims

1. A copper alloy powder for additive manufacturing, composed of a copper alloy containing Mn in the range of 3% by mass or more and 50% by mass or less, with the balance being Cu and inevitable impurities, having a volume average particle size of 10 μm or more and 150 μm or less, and a ratio Da / Dt of the powder loose bulk density Da to the powder true density Dt of 0.4 or more, obtaining the integrated intensity values for the Cu and O peaks in the XPS analysis of the powder surface, and the Cu / O abundance ratio obtained by performing concentration conversion by the relative sensitivity coefficient method being 0.1 or more, Among the Cu peaks in the XPS analysis of the powder surface, the Cu2p3 / 2 peak is separated into two peaks at 933.7 eV derived from CuO and at 932.5 - 932.7 eV derived from Cu or Cu ２ O. The ratio of the integrated intensity values of each peak is used as the abundance ratio of each, and the ratio of CuO among the Cu peaks is taken as the value of CuO / (Cu + Cu ２ O + CuO), and the ratio of the total of Cu and Cu ２ O (Cu + Cu ２ O) to CuO ((Cu + Cu ２ O) / CuO) is 1 or more, characterized by a copper alloy powder.

2. The copper alloy powder according to Claim 1, further characterized by containing one or more selected from Sn, In, and Ni in a total amount in the range of 1% by mass or more and 40% by mass or less.

3. The copper alloy powder according to Claim 1 or Claim 2, further characterized by containing one or more selected from Si, Al, and Ti in a total amount in the range of 0.5% by mass or more and 10% by mass or less.

4. The copper alloy powder according to any one of Claims 1 to 3, further characterized by containing one or two selected from Zn and P in a total amount of 10% by mass or less.

5. Among the Cu peaks in the XPS analysis of the powder surface, the Cu2p3 / 2 peak was separated into two peaks at 933.7 eV derived from CuO and 932.5 - 932.7 eV derived from Cu or Cu ２ O. The ratio of the integrated intensity values of each peak was taken as the abundance ratio of each, and the ratio of CuO among the Cu peaks was taken as the value of CuO / (Cu + Cu ２ O + CuO), The copper alloy powder according to any one of Claims 1 to 4, characterized in that the ratio of CuO is 40% or less.

6. Using the FIB (Focused Ion Beam) method to process the cross-section of the powder for observation, then observing the cross-section with SEM, and using EDS (Energy Dispersive X-ray Spectroscopy) to measure the peak derived from O (oxygen) in the depth direction, and taking the depth until the O concentration (oxygen concentration) becomes 0.5 at% or less as the thickness of the surface oxide product film, The copper alloy powder according to any one of Claims 1 to 5, characterized in that the thickness of the surface oxide product film is 3 μm or less.

7. The copper alloy powder according to any one of Claims 1 to 6, characterized by having antibacterial properties.

8. An additive manufactured object characterized by being formed using the copper alloy powder according to any one of Claims 1 to 7.

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