Metal powder for laminate molding and method for producing metal powder for laminate molding

Abstract

A metal powder for lamination molding, the metal powder comprising: copper-containing particles (1) containing copper; and a laser absorbing powder (2) adhered to the surface of the copper-containing particles (1).

Description

Technical Field

[0001] The present specification discloses a metal powder for laminated modeling and a method for manufacturing the same. Background Art

[0002] In metal layer modeling, which is one of the additive manufacturing (so-called AM) technologies, for example, thinly laid metal powder is sometimes irradiated with a laser beam or an electron beam based on the cross-sectional data of the object to be modeled, and a layer is formed by melting and solidifying or sintering a portion of it. The metal powder on the layer is repeatedly deposited and irradiated with a laser beam, etc., thereby modeling the object by stacking layers.

[0003] When a molded object made of copper or a copper alloy having excellent electrical conductivity and thermal conductivity is molded by such a layered molding, copper powder or copper alloy powder is used as the metal powder.

[0004] Here, copper and copper alloys not only have low laser absorption rates, but also high thermal conductivity, so the heat generated by the laser beam is easily dissipated. Therefore, for copper powder and copper alloy powder, if they are not irradiated with a laser beam with a higher output power than usual for a long time, they cannot be fully melted or sintered, and sometimes it is impossible to efficiently perform stacking modeling. In contrast, for example, in Patent Document 1, with the purpose of "providing a copper powder for a 3D printer that has a high absorption rate when irradiated with laser and can efficiently input heat, thereby enabling fusion bonding with a low-energy laser and a method for manufacturing the same", a "copper powder with an absorption rate of 18.9% to 65.0% for light of wavelength λ = 1060nm and an index represented by the absorption rate / oxygen concentration of light of wavelength λ = 1060nm of 3.0 or more" is proposed.

[0005] In addition, regarding copper alloy powder, Patent Document 2 describes "a metal powder for laminated molding, the metal powder containing at least one of chromium and silicon in an amount of 0.10 mass % or more and 1.00 mass % or less, the total amount of the chromium and the silicon being 1.00 mass % or less, and the remainder being copper". According to Patent Document 2, it can be seen that such "metal powder" can "provide a laminated molding made of a copper alloy that can achieve both mechanical strength and electrical conductivity".

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2018-178239

[0009] Patent Document 2: Japanese Patent Application Publication No. 2016-211062 Summary of the invention

[0010] Problems to be solved by the invention

[0011] Furthermore, since the laser absorption rate of copper powder or copper alloy powder is low, when using them for stacking molding, the laser beam is difficult to be absorbed by the copper powder or copper alloy powder. As a result, the melting or sintering of the copper powder or copper alloy powder is insufficient, resulting in a molded object with low density and conductivity.

[0012] In this specification, a metal powder for laminated modeling and a method for producing the metal powder for laminated modeling are provided. The metal powder for laminated modeling has a high laser absorptivity and can help improve the conductivity of a modeled object produced during laminated modeling.

[0013] Solutions for solving problems

[0014] The metal powder for laminated modeling disclosed in this specification includes: copper-containing particles containing copper; and laser absorbing powder attached to the surface of the copper-containing particles.

[0015] The method for producing metal powder for laminated modeling disclosed in this specification includes the steps of mixing copper powder or copper alloy powder with laser absorbing powder and attaching the laser absorbing powder to the surfaces of copper-containing particles of the copper powder or copper alloy powder.

[0016] Effects of the Invention

[0017] The metal powder for laminated modeling has a high laser absorptivity, which can help improve the conductivity of the modeled object produced during laminated modeling. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is a cross-sectional view schematically showing powder-attached particles contained in the metal powder for laminated modeling according to one embodiment. DETAILED DESCRIPTION

[0019] Hereinafter, the embodiment of the metal powder for laminated molding and the method for producing the same will be described in detail with reference to the accompanying drawings. It should be noted that reference numerals are used for description as needed, but may be omitted when they are not necessary.

[0020] (Metal powder)

[0021] like Figure 1 As schematically shown, a metal powder for laminated modeling (hereinafter, also simply referred to as “metal powder”) according to one embodiment includes powder-attached particles 3 in which laser absorbing powder 2 is attached around copper-containing particles 1 containing copper.

[0022] The copper-containing particles 1 are copper or copper alloy particles containing copper. In the case of copper-containing particles 1 made of copper, the copper content of the metal powder is, for example, 99.9% by mass or more. In addition, in the case of copper-containing particles 1 made of copper alloys, sometimes the metal powder contains copper, for example, at 90% by mass to 99.9% by mass, and as an alloying element, contains one or more selected from the group consisting of Al, Cr, Fe, Ni, Nb, P, Si, Ti, Zn and Zr, and in the case of containing multiple elements, their total is 0.1% by mass to 10% by mass. The content of copper and alloying elements in the metal powder can be measured by inductively coupled plasma optical emission spectrometry (ICP-OES).

[0023] Laser absorbing powder 2 is attached around the copper-containing particles 1. Therefore, when metal powder is used for lamination molding, the laser absorbing powder 2 around the copper-containing particles 1 promotes the absorption of the laser beam to the copper-containing particles 1, and the copper-containing particles 1 become easy to melt or sinter. As a result, a high-density molded object can be produced, and the conductivity of the molded object is expected to be improved.

[0024] The laser absorbing powder 2 is preferably a substance having a higher melting point than copper. In addition, the laser absorbing powder 2 preferably contains an element or compound that does not easily react with copper. The reason is that when the laser absorbing powder 2 contains an element or compound that can be solid-dissolved in copper, sometimes it is solid-dissolved in copper during stacking molding, resulting in the electrical conductivity of the molded object not becoming so high. It should be noted that, when the copper-containing particles 1 are made of copper alloy, the substance contained in the laser absorbing powder 2 is preferably a substance that reacts with the alloy element that is solid-dissolved in copper and precipitates. When the substance reacts with the alloy element and precipitates, the parent phase becomes approximately pure copper, and the electrical conductivity is improved.

[0025] As the material of the laser absorbing powder 2, for example, single substance B (boron), TiB 2 Borides, Y 2 O 3 Oxides.

[0026] When the laser absorbing powder 2 contains B, B in the laser absorbing powder 2 may be a single substance or TiB. 2 For example, the laser absorbing powder 2 attached to the surface of the copper-containing particle 1 made of copper can be made of TiB 2 Alternatively, the laser absorbing powder 2 attached to the surface of the copper-containing particle 1 made of a copper alloy (Cu-Ti alloy, etc.) can be a substance containing a single substance B. B of the laser absorbing powder 2 attached to the surface of the copper-containing particle 1 made of a copper alloy reacts with its alloy element during stacking and precipitates, and the parent phase becomes substantially pure copper, thereby improving the conductivity.

[0027] The laser absorbing powder 2 attached to the periphery of the copper-containing particle 1 contains TiB 2 In the case of the above, the metal powder containing such powder-attached particles 3 becomes a substance containing Ti and B. The Ti content of the metal powder is preferably 1% by mass or less, and more preferably 0.5% by mass or less, relative to the total mass of the metal powder. By making the Ti content to be a small amount to some extent, the electrical conductivity of the molded object can be effectively improved. For example, the Ti content is sometimes set to 0.01% by mass or more, and typically, it is sometimes set to 0.1% by mass to 0.5% by mass. In the laser absorbing powder 2 containing TiB 2 In the case of B content, it is ideal that the B content varies according to the Ti content, and the mass-based B content / (Ti content + B content) is preferably 0.1 or more and less than 0.5, and more preferably 0.2 or more and less than 0.4. When the B content / (Ti content + B content) is set within this range, it can be expected that TiB will be formed in the molded object. 2 When TiB is formed in the object 2 When , the parent phase becomes almost pure copper, and the conductivity is improved.

[0028] The Ti content and the B content of the metal powder can be measured by inductively coupled plasma optical emission spectrometry (ICP-OES).

[0029] The laser absorbing powder 2 attached to the periphery of the copper-containing particle 1 contains Y 2 O 3 In the case of , the metal powder containing such powder-attached particles 3 becomes a substance containing Y. The Y content of the metal powder is preferably 1 mass % or less, more preferably 0.5 mass % or less, relative to the total mass of the metal powder. If the Y content is too much, the conductivity of the shaped object will not be improved. The Y content is sometimes, for example, 0.01 mass % or more, and typically, it is sometimes set to 0.1 mass % to 0.5 mass %. Ideally, the oxygen content varies according to the Y content, and the mass-based oxygen content / (Y content + oxygen content) is preferably 0.1 or more and less than 1, more preferably 0.2 or more and less than 0.4. When the oxygen content / (Y content + oxygen content) is set within this range, it can be expected that Y will be formed in the shaped object. 2 O 3 When Y is formed in the model 2 O 3 When , the parent phase becomes almost pure copper, and the conductivity is improved.

[0030] The Y content of the metal powder can be measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). The oxygen content of the metal powder can be measured by an inert gas fusion method. Here, a 1 g sample of the metal powder can be measured twice using TCH600 manufactured by LECO, and the average value is set as the oxygen content.

[0031] As described above, it can be confirmed by X-ray photoelectron spectroscopy (XPS) that the laser absorbing powder 2 attached to the periphery of the copper-containing particle 1 contains TiB. 2 , Y 2 O 3 .

[0032] The average particle size D50 of the metal powder is preferably 10 μm to 150 μm. By making the average particle size D50 not too small, in addition to being difficult to fly during molding, the metal powder becomes easy to handle, and the required fluidity can be exerted, and it can be laid in the desired position, and the molding property is improved. By maintaining the average particle size D50 to a certain extent, the energy required to melt or sinter the metal powder by laser beam can be suppressed to a small level, and the molding accuracy can be improved.

[0033] The above-mentioned average particle diameter D50 refers to the particle diameter of the metal powder measured by a laser diffraction / scattering particle diameter distribution measuring device, and in the particle diameter histogram (particle diameter distribution diagram) obtained thereby, the accumulation of the frequency of the volume basis of the metal powder becomes 50%, and is measured based on JIS Z8825 (2013). More specifically, in the measurement of the average particle diameter D50, MT3300EXII manufactured by MicrotracBEL can be used, the solvent can be pure water, and the refractive index can be set to 1.33.

[0034] In conventional laser lamination molding, a fiber laser with a wavelength of about 1060 nm is used, so the laser absorptivity of the metal powder is measured by the reflectivity at a wavelength of 1060 nm and calculated under the following apparatus and conditions. The laser absorptivity of the metal powder is preferably 15% or more, more preferably 25% or more.

[0035] Manufacturer: Shimadzu Corporation.

[0036] Device name: Spectrophotometer (MPC-3100, using powder holder).

[0037] Measuring wavelength: 300~1500mm.

[0038] Slit width: 20nm.

[0039] Reference: BaSO 4 .

[0040] Measured physical property value: reflectivity.

[0041] Absorption rate (%) = 1 - (reflectivity (%)).

[0042] (Manufacturing method)

[0043] When manufacturing the metal powder as described above, for example, copper powder or copper alloy powder is first prepared. The copper powder or copper alloy powder can be prepared by purchasing already prepared powder or by atomization or other various methods.

[0044] The copper powder mainly includes copper-containing particles containing copper, and the copper content is preferably 99.9% by mass or more (purity is 3N or more). In addition, the copper alloy powder mainly includes copper-containing particles containing copper alloy. As the copper alloy powder, the copper content is 80% by mass or more, further 85% by mass or more, further 90% by mass or more, and further 99% by mass or more, and in addition to copper, one or more selected from the group consisting of Al, Cr, Fe, Ti, Ni, Nb, P, Si, Zn and Zr are sometimes used as alloy elements.

[0045] The copper powder or copper alloy powder is preferably sized by screening or the like as needed, and the average particle size D50 is 10 μm to 150 μm. The average particle size D50 has the same meaning as the average particle size D50 described above for the metal powder and can be measured by the same method.

[0046] The copper powder or copper alloy powder described above can be mixed with laser absorbing powder so that the laser absorbing powder adheres to the surface of copper-containing particles, thereby producing metal powder.

[0047] The laser absorbing powder mixed with the copper particles of the copper powder or copper alloy powder is preferably a fine-particle powder. The average particle size D50 of the laser absorbing powder is preferably 10 μm or less. The average particle size D50 has the same meaning as the above-mentioned average particle size D50.

[0048] However, fine laser absorbing powders such as those with an average particle size D50 of 10 μm or less may sometimes aggregate. If the laser absorbing powders are highly aggregated, the aggregates can be easily eliminated by sieving them together with the copper powder or copper alloy powder after mixing with the copper powder or copper alloy powder.

[0049] The mixing method may be any method such as mixing using a ball mill or a mixer. For example, copper powder or copper alloy powder is put into a ball mill, and TiB 2 powder or B powder, or Y 2 O 3 The laser absorbing powder such as powder is rotated at 50 rpm or more for about 10 to 90 minutes, thereby forming a Figure 1 The powder-adhered particles 3 shown are metal powders.

[0050] By carrying out the above-described process, a metal powder including copper-containing particles and laser absorbing powder can be produced.

[0051] Example

[0052] Next, the above-mentioned metal powder for laminated modeling was tried to be produced, and its effect was confirmed, so it is described below. However, the description here is only for the purpose of illustration and is not intended to be limited to this.

[0053] A pure copper powder or a copper alloy powder having an average particle size D50 of about 30 μm to 45 μm is prepared. The copper content of the pure copper powder is 99.9% by mass, and the copper alloy powder is a copper alloy powder containing 0.3% by mass of Ti.

[0054] (Example 1)

[0055] The copper powder and TiB 2 The powder (laser absorbing powder) was mixed for 30 minutes to prepare a metal powder in which the laser absorbing powder adhered to the surface of the copper-containing particles.

[0056] (Example 2)

[0057] Using a ball mill, the copper powder and Y 2 O 3 The powder (laser absorbing powder) was mixed for 30 minutes to prepare a metal powder in which the laser absorbing powder adhered to the surface of the copper-containing particles.

[0058] (Example 3)

[0059] The copper alloy powder and the B powder (laser absorbing powder) were mixed for 30 minutes using a ball mill to prepare a metal powder in which the laser absorbing powder adhered to the surface of copper-containing particles.

[0060] (Comparative Example 1)

[0061] The above copper powder was used as metal powder as it is.

[0062] (evaluate)

[0063] The average particle size D50 and the content of the constituent components of the laser absorbing powder were confirmed by the above-mentioned method. The results are shown in Table 1. The metal powders of Examples 1 and 2 were analyzed by the above-mentioned method to confirm the presence of laser absorbing powder of a predetermined material.

[0064] In addition, in order to confirm the effect of each metal powder, a 20 mm square cubic shape was made using the metal powder using a molding machine, and the density and conductivity of the shape were evaluated. The molding machine was AM400 manufactured by Renishaw, the output power was set to 400 W, and the scanning speed was set to 400 mm / sec.

[0065] As the density of the above-mentioned molded object, the relative density is obtained by measuring the ratio of the area occupied by the pores to the area of ​​the image observed by an optical microscope. The relative density is calculated according to the formula: relative density = ((area of ​​the molded object - area of ​​the pores) / area of ​​the molded object) × 100 (%). It should be noted that the same calculation is also performed when the molded object is made of metal powder made of copper alloy powder.

[0066] As for the electrical conductivity, an eddy current was made to flow through the molded object, and the electrical conductivity was calculated based on the current value of the eddy current. Furthermore, the molded object was subjected to an aging treatment in an Ar atmosphere at 1000°C for 2 hours in Example 1 and at 700°C for 2 hours in Example 3 to confirm whether the electrical conductivity could be improved.

[0067] Table 1 shows the results.

[0068] [Table 1]

[0069]

[0070] The conductivity of Comparative Example 1 is less than 80%, while the shaped objects of Examples 1 and 3 made under the same molding conditions can achieve a conductivity of 90% IACS or more after aging treatment. Example 2 achieves 95% IACS or more even without aging treatment. This confirms that the laser absorbing powder is effective.

[0071] From the above, it can be seen that the laser absorptivity of the above-mentioned metal powder is improved, which is effective for the molding of high-conductivity molded objects.

[0072] Description of Reference Numerals

[0073] 1: Copper-containing particles; 2: Laser-absorbing powder; 3: Powder-attached particles.

Claims

1. A metal powder for laminated modeling, which is a metal powder for laminated modeling, The metal powder for laminated modeling includes: copper-containing particles containing copper; and laser absorbing powder attached to the surface of the copper-containing particles.

2. The metal powder for laminated molding according to claim 1, in, The laser absorbing powder contains B.

3. The metal powder for laminated molding according to claim 2, in, The laser absorbing powder contains TiB 2 .

4. The metal powder for laminated molding according to claim 3, in, The Ti content is 0.1% to 0.5% by mass based on the total mass of the metal powder.

5. The metal powder for laminated molding according to claim 1, in, The laser absorbing powder contains oxides.

6. The metal powder for laminated molding according to claim 5, in, The oxide is Y 2 O 3 .

7. The metal powder for laminated molding according to claim 6, in, The Y content is 0.1 mass % to 0.5 mass % based on the total mass of the metal powder.

8. The metal powder for laminated molding according to any one of claims 1 to 7, in, The average particle size D50 is 10 μm to 150 μm.

9. A method for producing metal powder for laminated modeling, which is a method for producing metal powder for laminated modeling, The method for producing the metal powder for laminated modeling includes the following steps: mixing copper powder or copper alloy powder with laser absorbing powder, and making the laser absorbing powder adhere to the surface of copper-containing particles of the copper powder or copper alloy powder.

10. The method for producing the metal powder for laminated molding according to claim 9, in, Use containing TiB 2 or Y 2 O 3 The laser absorbing powder is a laser absorbing powder.

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