JP2019108587A - Metal powder and method for producing the same, and lamination-molded article and method for producing the same - Google Patents

Abstract

To provide a metal powder material for lamination molding, capable of achieving high densification and high conductivity of a molded article.SOLUTION: Metal powder for lamination molding of this invention comprises: 0.02 mass% or more in total of one or more non-metallic elements selected from the group consisting of sulfur, nitrogen and carbon; and 90 mass% or more of copper. For example, the metal powder for lamination molding can be obtained by bringing copper powder into contact with a solution containing the one or more non-metallic elements selected from the group consisting of sulfur, nitrogen and carbon.SELECTED DRAWING: None

Description

  The present invention relates to a metal powder that can be suitably used as a material for additive manufacturing, a method for producing the same, and a method for producing a laminated object. Furthermore, the present invention relates to a laminate.

  The three-dimensional additive manufacturing technology can produce a product having a complicated shape which can not be achieved by conventional processing technology such as cutting, and is expected to be applied to various fields. In recent years, various studies have been made on the additive manufacturing method using metal powder.

  Copper is often used for parts that are required to have mechanical strength and high conductivity, and development of additive manufacturing technology using copper is required. However, it is known that a laminate-molded article using copper powder has a large number of voids and low mechanical strength and conductivity (see, for example, Patent Document 1).

Unexamined-Japanese-Patent No. 2016-211062

  In patent document 1, it is reported that the laminated molded article which is excellent in mechanical strength and has high conductivity is obtained by using the copper alloy powder containing chromium or silicon as a lamination molding material. Although the laminate-molded product obtained by using the copper alloy powder as a material can improve the mechanical strength and the conductivity as compared with the case of using a powder of pure copper as a material, the relative density to the theoretical density is smaller than that of standard soft copper. In addition, when an alloy material is used, it is difficult to sufficiently increase the conductivity depending on the metal composition even when the layered product has a high density.

  In view of the above, it is an object of the present invention to provide a metal powder material for additive manufacturing which can realize densification and high conductivity of a shaped object.

  The metal powder of the present invention contains 90% by mass or more of copper, and contains 0.02% by mass or more of at least one nonmetallic element selected from the group consisting of sulfur, nitrogen and carbon. The metal powder of the present invention is suitably used as a laminate molding material.

  The average particle size of the metal powder is preferably about 0.5 to 200 μm. The metal powder preferably comprises the above nonmetallic element, copper, 9% by mass or less of oxygen and unavoidable impurities. The metal powder preferably contains 0.02% by mass or more of sulfur as a nonmetal element.

  In the metal powder, the concentration of the nonmetallic element in the surface layer portion is preferably higher than the concentration of the nonmetallic element in the central portion. For example, by bringing copper powder into contact with a solution containing a nonmetallic element, a film is formed on the surface layer, and a metal powder having a high concentration of nonmetallic element in the surface layer can be obtained. Contact with the solution may increase the surface area of the metal powder. In addition, the light reflectance of the metal powder may be reduced by contact with a solution.

  Furthermore, the present invention relates to a lamination molding method using the above-mentioned metal powder. A powder bed method, a metal deposition method or the like can be adopted as the additive manufacturing method.

  In the powder bed method, a powder layer forming step of forming a powder layer containing metal powder, and energy such as laser, electron beam, plasma or the like is applied to a predetermined position of the powder layer to solidify the metal powder to form a shaped layer. By sequentially repeating the forming process, the forming layer is laminated to obtain a layered formed article.

  In the metal deposition method, the shaped layer is laminated by repeating the steps of supplying the heated melt of metal powder to a predetermined position and solidifying it to form the shaped layer.

  Furthermore, the present invention relates to a laminate. The layered object according to one embodiment contains 0.02% by mass or more in total of one or more nonmetallic elements selected from the group consisting of sulfur, nitrogen and carbon, and 90% by mass or more of copper. 10% or less is preferable for the porosity calculated | required from cross-sectional observation of a laminate-molded article, and 30% IACS or more of conductivity of a laminate-molded article is preferable.

  By performing lamination molding using the metal powder of the present invention as a material, it is possible to form a lamination-shaped object having a low porosity and high density and high conductivity.

It is a cross-sectional microscope observation image of the laminate-molded article obtained in the Example. It is a SEM image of sulfided copper powder of an example. It is the graph which plotted the sulfur content of sulfided copper powder, and the porosity of a laminate-molded article.

[Metal powder]
The metal powder of the present invention contains 90% by mass or more of copper, and contains one or more nonmetallic elements selected from the group consisting of sulfur, nitrogen and carbon. This metal powder can be used as a laminate molding material. Content of the said nonmetallic element in metal powder is 0.02 mass% or more. When the metal powder contains a non-metal element, a low-porosity, high-density layered product can be obtained. When the content of the nonmetallic element is less than 0.02% by mass, the properties of the metal powder are close to the properties of a pure copper (oxygen-free copper) powder, and it becomes difficult to form a high density laminate-shaped article. From the viewpoint of increasing the density and conductivity of the laminate-molded product, the content of the nonmetallic element in the metal powder is preferably 10% by mass or less.

  In order to form a low-porosity small and high-density laminate-molded article, the content of the nonmetallic element in the metal powder is preferably 0.03 to 7% by mass, and more preferably 0.05 to 5% by mass. 0.1 to 3% by mass is more preferable. In order to obtain a layered product with higher conductivity, the content of the nonmetallic element in the metal powder is preferably 2% by mass or less, more preferably 1% by mass or less, and still more preferably 0.5% by mass or less .

  It is particularly preferable that the metal powder contains sulfur among the above nonmetallic elements. Since sulfur compounds such as copper sulfide have higher conductivity than compounds of other nonmetallic elements, even if sulfur elements remain in the laminate-molded product, it is easy to achieve high conductivity. In addition, since copper sulfide has a low light reflectance, a copper sulfide film is formed on the surface of copper powder, so it becomes easy to absorb a laser etc. as an energy source for layered manufacturing, and it is expected to improve energy utilization efficiency it can. In a particularly preferred embodiment of the present invention, the metal powder contains sulfur as a nonmetallic element in the above range.

  The metal powder may contain an impurity element in addition to copper and the nonmetallic element described above. The impurity element is an element which is inevitably mixed in the production of the raw material copper powder, or an element which is inevitably mixed in the case where the copper powder is treated with a solution. As an unavoidable impurity element, the phosphorus etc. which are mixed, for example, when producing a raw material powder by the atomization method are mentioned. The amount of such unavoidable impurities is, for example, less than 0.1% by mass.

  In addition, during the treatment with a solution, oxygen may be mixed with the oxidation of the metal or the like. The oxygen atom contained in the metal powder is, for example, 9% by mass or less, preferably 7% by mass or less, and more preferably 5% by mass or less. The metal powder contains a small amount (for example, about 0.01 to 5% by mass) of oxygen, thereby promoting desorption by vaporization of nonmetallic elements such as sulfur, nitrogen, and carbon by heating at the time of additive manufacturing, etc. In some cases, it is expected that the porosity of the shaped article will be reduced and the conductivity will be improved. If the oxygen content in the metal powder is excessively high, the amount of residual oxygen in the shaped article may be increased, and the conductivity of the shaped article may be reduced.

  The above nonmetallic element may be deposited as a film on the surface of the copper powder, may form a compound with copper, or may form a compound with an element other than copper. The above nonmetallic element may be contained in the whole of the metal powder at equal concentration, or may have a concentration distribution. For example, when copper powder is used as a raw material powder and the powder is surface-treated with a solution containing a nonmetallic element, the nonmetallic element is introduced into the surface layer of the powder. Therefore, in the metal powder, the concentration of the nonmetallic element in the surface layer portion tends to be larger than the concentration of the nonmetallic element in the central portion.

  The surface layer portion of the powder is maintained while maintaining the characteristics of copper such as high conductivity by the high concentration of nonmetal elements in the surface layer portion of the powder and the low concentration of nonmetal elements in the center portion (composition is close to pure copper) To improve the processability by additive manufacturing. Therefore, the metal powder which has concentration distribution of such a nonmetallic element is suitable for formation of the high-density and high conductivity layered product.

  The shape of the metal powder is not particularly limited, and may be spherical, flake-like, plate-like, needle-like, amorphous or the like. In the case of performing lamination molding by the powder bed method described later, a spherical shape or a substantially spherical shape having an aspect ratio of 2 or less is preferable because the gaps between the powders can be spread little at the time of forming the powder layer. Irregularities may be formed on the surface of the metal powder. In addition, secondary particles may be deposited on the surface of the metal powder.

  The particle diameter of the metal powder is not particularly limited, and may be appropriately adjusted in accordance with the lamination molding method, the lamination thickness of lamination molding, and the like. The average particle diameter of the metal powder is, for example, 0.1 to 200 μm, preferably 1 to 100 μm, more preferably 3 to 70 μm, and still more preferably 5 to 50 μm. The average particle size is a median size obtained from a particle size distribution measured by a laser diffraction type particle size distribution measuring apparatus.

[Preparation of metal powder]
The method for producing the metal powder of the present invention is not particularly limited, and a material having a predetermined composition may be powdered, or the composition may be adjusted by surface treatment of the raw material powder. In order to produce a metal powder having a relatively high concentration of nonmetallic elements in the surface layer portion, it is preferable to use a copper powder as a raw material and contact the raw material copper powder with a solution containing a nonmetallic element to perform surface treatment .

  As a raw material copper powder, the copper powder formed of the mechanical method, the chemical method, the atomizing method etc. can be used without a restriction | limiting. In order to obtain spherical or substantially spherical powder, gas atomizing method, water atomizing method, disk atomizing method, plasma rotating electrode method, thermal plasma method and the like are preferable. In general, since the particle size hardly changes before and after the surface treatment, as the raw material copper powder, one having a particle size equivalent to the particle size of the above-mentioned metal powder is preferable.

  As the surface treatment solution, a solution containing one or more nonmetallic elements selected from the group consisting of sulfur, nitrogen and carbon is used. The surface treatment solution is capable of forming a film of a nonmetallic element and a compound of copper on the surface of copper powder, capable of forming a film containing a nonmetallic element on the surface of copper powder, or on the surface of copper powder Those which can precipitate secondary particles containing nonmetallic elements are preferably used. The compound of the nonmetallic element and copper includes copper sulfide, copper nitride and copper carbide. As a film which may be formed on the surface of copper powder other than copper compounds, sulfur-containing organic compounds, nitrogen-containing organic compounds, carbon and the like can be mentioned. In addition, these coating materials may be deposited on the surface of the copper powder as secondary particles.

For example, when forming a copper sulfide film on the surface of a copper powder, as a sulfur source, potassium sulfide (K ₂ S), sodium sulfide (Na ₂ S), barium sulfide (BaS), ammonium sulfide ((NH ₄ ) ₂ It is preferable to treat the copper powder with an aqueous solution containing a sulfide such as S). When the copper sulfide film is formed on the surface of the copper powder, the surface tends to be blackened and the light reflectance tends to be reduced.

  When using an aqueous solution of ammonium sulfide as the surface treatment solution, the concentration of sulfur in the aqueous solution of ammonium sulfide is preferably 0.0001% by mass or more, more preferably 0.0005% by mass or more, from the viewpoint of promoting sulfurization on the surface of copper powder. .001% by mass or more is more preferable, and 0.002% by mass or more is particularly preferable. The upper limit of the sulfur concentration in the ammonium sulfide aqueous solution is not particularly limited, but in order to facilitate the adjustment of the treatment rate and the introduction amount of sulfur element, 5% by mass or less is preferable, 1% by mass or less is more preferable 0.5 % By mass or less is more preferable, and 0.3% by mass or less is particularly preferable. Also when using sulfides other than ammonium sulfide, it is preferable that the sulfur concentration in aqueous solution is in the said range.

  Before the sulfidation treatment, the oxide film formed on the surface of the copper powder may be removed (see, for example, JP-A-2015-129336). In addition, after the copper powder on which the oxide film is formed is treated with a reducing agent, a copper sulfide film may be formed on the surface of the copper powder by a method of contacting with a sulfide aqueous solution in the presence of a reducing agent (for example, See open 2014-5491).

  The surface treatment solution may contain, in addition to the sulfur source, the nitrogen source and the carbon source, a component capable of dissolving copper. By using a solution containing a component capable of dissolving copper and a nonmetallic element, a film or a secondary particle containing the nonmetallic element may be formed on the surface while dissolving the copper surface. As a component which can melt | dissolve copper, the oxidizing agent of a copper, an acid component, etc. are mentioned, for example.

  Examples of oxidizing agents for copper include metal ions such as cupric ions and ferric ions, nitric acid, hydrogen peroxide and the like. Examples of the acid component include hydrohalic acids such as hydrofluoric acid, hydrochloric acid (hydrochloric acid), hydrobromic acid and hydroiodic acid, and inorganic substances such as sulfuric acid, nitric acid, phosphoric acid, perchloric acid and sulfamic acid Examples of the acid include organic acids such as sulfonic acid and carboxylic acid. Since the acid component has the function of dissolving the copper eluted from the copper powder in the solution, the use of the treatment solution containing the acid component may result in the formation of fine irregularities on the powder surface. In addition, when copper dissolved in a solution forms a compound with a nonmetallic element in the solution, a film or a secondary particle containing the nonmetallic element and copper may be formed on the surface of the powder. When the concavo-convex shape and secondary particles are formed on the surface, the surface area of the powder is increased, and the light reflectance tends to be reduced accordingly.

  The surface treatment solution may contain various additives. For example, a nonionic surfactant as an antifoaming agent or a complexing agent such as pyridine may be added to improve the stability of copper. As additives, various amines, pyrrole, pyrazole, imidazole, triazole, tetrazole, oxazole, oxadiazole, isoxazole, thiazole, isothiazole, triazine, tetrazine, piperazine, pyrimidine and the like, nitrogen-containing cyclic compounds, or derivatives thereof Etc. may be used. The inclusion of additives may accelerate the deposition of secondary particles on the surface of the copper powder. Furthermore, various asperities may be formed on the surface of the copper powder by using various water-soluble polymers as additives.

  As the solvent for the surface treatment solution, water, alcohols such as ethanol and isopropyl alcohol, esters, ethers, ketones, aromatic hydrocarbons and the like can be used. As water, water from which ionic substances and impurities have been removed is preferable, and for example, ion-exchanged water, pure water, ultrapure water and the like are preferably used.

  The method of contacting the raw material powder with the surface treatment solution is not particularly limited, and a method of bringing a mist-like solution into contact with the surface of the raw material powder by a spray method or a method of immersing the raw material powder in a solution can be employed. The temperature and the treatment time (the contact time with the solution) during the treatment are not particularly limited, and may be set according to the shape and particle diameter of the raw material powder, the composition of the surface treatment solution, the composition and surface shape of the target metal powder, etc. Just do it. From the viewpoint of appropriately controlling the composition, surface shape and the like of the powder, it is preferable to remove the solution from the surface of the powder after the treatment. For example, the solution can be removed from the powder surface by water washing.

  As described above, by bringing the raw material powder and the surface treatment solution into contact with each other, the nonmetal element is introduced into the surface layer of the copper powder, and a metal powder suitable for a laminate molding material can be obtained. The surface treatment may be a treatment to make the light reflectance of the metal powder smaller than the light reflectance of the raw material copper powder in addition to the introduction of the nonmetal element to the metal powder, and the surface area of the metal powder is a raw material copper powder It may be processing to make it larger than the surface area of.

[Laminated modeling method]
A laminate-molded article can be obtained by performing lamination molding using the above-mentioned metal powder. The lamination molding method of the present invention can be carried out in the same manner as the conventional lamination molding method using metal powder, except that the above-mentioned metal powder is used as the lamination molding material.

  As a lamination molding method using metal powder, a method of applying high density energy to metal powder and melting and solidifying it is suitable. As an energy source for melting and solidifying the metal powder, a laser, an electron beam, plasma and the like can be mentioned. Among them, a method using a laser is preferable because it can locally melt high-density energy to melt the metal powder. The powder bed method and the metal deposition method can be mentioned as a lamination molding method of metal powder using a laser.

  In the powder bed method, metal powder is arranged in a layer to form a powder layer, and energy is irradiated to a predetermined position of the powder layer to solidify and solidify the metal powder to form a shaped layer. By repeating the formation of the powder layer and the formation of the shaped layer by energy irradiation, it is possible to produce a three-dimensional laminated three-dimensional object of any shape. In the metal deposition method, the metal powder is heated and melted by energy such as a laser, and the heated molten material is supplied to a predetermined position and solidified at the predetermined position to form a shaped layer. A three-dimensional laminated three-dimensional object can be produced by repeating the formation of the formation layer.

  Among the above, the powder bed method has the advantages of high processing accuracy and capable of forming a high-density shaped object. Hereinafter, a layered manufacturing method by the powder bed method will be described.

  In additive manufacturing, first, slice data for additive manufacturing is created based on three-dimensional shape data of a shaped object. For example, three-dimensional shape data produced by 3D-CAD or the like is converted into STL (Stereolithography) data by element division by the finite element method, and slice data is created from the STL data. The slice data is obtained by dividing the STL data of a shaped object into N along the height direction (modeling direction), and includes shape data (xy coordinates) of each of the shaped layers of the first to N-th layers. . The slice thickness d is about 10 to 150 μm. This slice thickness d corresponds to the lamination thickness of one layer in additive manufacturing.

  The additive manufacturing is performed based on the slice data. In order to suppress oxidation of a shaped article, it is preferable to carry out additive manufacturing in an inert gas atmosphere such as nitrogen, argon or helium or in a reduced pressure atmosphere.

(Powder layer forming process)
The above-mentioned metal powder is spread over a predetermined area on the table which can be raised and lowered to form a powder layer of thickness d. The powder layer may contain a laser absorber etc. in addition to the above-mentioned metal powder. The surface of the powder layer may be smoothed with a squeegee blade or the like as required.

(Forming process)
Energy is applied to a predetermined position of the powder layer based on the slice data. As described above, examples of the energy to be irradiated include a laser, an electron beam, plasma and the like, and a laser is particularly preferable. The powder layer may be heated in advance prior to energy irradiation by a laser or the like. The metal powder in the energy irradiated area solidifies through melting or sintering to form a shaped layer. The metal powder in the region where the energy was not irradiated remains in a powder state without solidifying.

As the laser, a fiber laser, a YAG laser, a carbon dioxide gas laser, a semiconductor laser or the like is used. The laser output is preferably about 50 to 1000 W. The scanning speed of the laser is, for example, about 1 to 5000 mm / sec. The scanning pitch of the laser is about 10 to 500 μm. The energy density of the laser is adjusted, for example, in the range of 50 to 1000 J / mm ³ . The energy density E of the laser is represented by E = P / v · s · d. P is the laser output, v is the scanning speed, s is the scanning pitch, and d is the slice thickness (stacking thickness).

  A shaped layer corresponding to the first layer of slice data is formed by the powder layer forming step and the shaping step described above. Thereafter, the table is lowered by the slice thickness d. Instead of lowering the table, the relative positional relationship between the powder layer and the laser light source may be adjusted by raising the laser light source. A metal powder is spread on the first layer after forming the forming layer to form a powder layer of the second layer, and laser is irradiated to a predetermined position of the powder layer based on the slice data of the second layer to form the forming layer. Form.

  Thereafter, the powder layer forming step and the shaping layer forming step by energy irradiation based on the slice data of the n-th layer (n ≦ N) are repeated for the third to N-th layers. Finally, the layered product is completed by removing the unsolidified metal powder in the area not irradiated with energy. The layered product may be subjected to post-treatment. Post treatments include, for example, heating. By performing post-processing such as heating, the mechanical strength and conductivity of the laminate-molded article may be improved.

[Layered object]
Shaped articles produced by additive manufacturing may have complicated shapes that can not be realized by cutting. In the present invention, since the metal powder containing copper as a main component is used as a laminate-modeling material, the resulting laminate-molded article contains copper as a main component. 90 mass% or more is preferable, as for content of copper in a laminate-molded article, 95 mass% or more is more preferable, and 97 mass% or more is more preferable.

  The composition of the layered object may be the same as or different from the metal powder as the layered material. Since nonmetallic elements such as sulfur, nitrogen, and carbon contained in the metal powder are easily vaporized and eliminated by heating at the time of additive manufacturing, the content of the nonmetallic element in the additive is the same as the nonmetallic elements in the metal powder. It tends to be smaller than the content of Similar to the metal powder, the layered product may contain unavoidable impurities.

  10% or less is preferable, 7% or less is more preferable, 5% or less is more preferable, and 3% or less is particularly preferable. As the porosity of the layered product is smaller, mechanical strength and conductivity tend to be improved. By using the metal powder of the present invention as the layered molding material, it is possible to form a layered molded article having a smaller porosity and a higher density than when a general copper powder is used.

  As one of the reasons why laminated shaped articles with a small porosity can be obtained by the metal powder of the present invention containing a nonmetallic element, the utilization efficiency of energy such as a laser to be irradiated to melt and solidify the metal powder is improved Be When a copper powder is brought into contact with a solution containing a nonmetallic element such as sulfur, carbon or nitrogen, a film of a copper compound such as copper sulfide, copper carbide or copper nitride may be formed on the surface. In addition, the contact of the solution with the copper powder may roughen the surface to form a fine uneven shape, or the secondary particles may be precipitated.

  Since copper compounds such as copper sulfide, copper carbide and copper nitride have lower light reflectance than metal copper, when a copper compound film is formed on the surface of copper powder, the light energy absorbed by the metal powder is increased It is thought that. When a fine uneven shape is formed on the surface of the copper powder, the specific surface area is increased. The specific surface area also increases when secondary particles are deposited on the surface of the copper powder. As the specific surface area increases, the light energy absorbed by the metal powder tends to increase. Thus, surface treatment of the copper powder causes formation of a compound film, formation of an uneven shape, precipitation of secondary particles, and the like, and the utilization efficiency of light energy is increased, so that the void ratio is small and high density. It is believed that a shaped object is obtained.

The conductivity of the layered product is preferably 30% IACS or more, more preferably 40% IACS or more, further preferably 50% IACS or more, and particularly preferably 60% IACS or more. In addition, IACS% is the electrical conductivity which prescribed | regulated the electrical conductivity (1.7241 * 10 < ^-20 > (micro | micron | mu) ohm * m) of annealing standard soft copper (International Annealed Copper Standard: IACS) as 100% IACS. When the layered product is used as an electrical material, the conductivity is preferably high. However, if it is 30% IACS or more, it has a conductivity equal to or higher than that of brass, so it can be sufficiently used as an electrical material.

  Compounds of copper and nonmetallic elements such as copper sulfide, copper carbide and copper nitride generally have significantly lower conductivity than copper, but the laminate-molded product produced using the metal powder of the present invention is the above-mentioned. Have a high conductivity. One of the reasons why the layered product has high conductivity is that the content of the nonmetallic element in the metal powder is small.

  As shown in the subsequent examples, the smaller the content of the nonmetal element of the metal powder, the higher the conductivity of the laminate-shaped article tends to be. On the other hand, when the content of the nonmetallic element is less than 0.02% by mass, the properties of the metal powder tend to be close to the properties of the untreated pure copper powder, and the porosity of the laminate-shaped article tends to be large. As described above, in the present invention, the nonmetallic element contained in the powder as the laminate shaping material is vaporized and eliminated by heating or the like at the time of laminate modeling, thereby containing the nonmetal element in the laminate shaped article. The amount is small, the void ratio is small, and a layered product with high density and high conductivity is obtained.

  Hereinafter, the present invention will be more specifically described by way of examples, but the present invention is not limited to these examples.

[Preparation of metal powder]
<Sulfurated copper powder 1>
Water atomized copper powder having an average particle diameter of 20 μm is placed in a container, and a 5-fold amount (weight ratio) of ammonium sulfide aqueous solution is poured onto the copper powder and stirred for 2 minutes at a temperature of 20 ° C. The solution was separated by filtration, and the surface of the powder was washed with ion exchanged water. As the ammonium sulfide aqueous solution, one obtained by diluting an ammonium sulfide aqueous solution having a sulfur concentration of 6% so that the sulfur concentration is 0.001 mass% was used. As a result of analysis by ICP emission spectroscopy, the obtained powder had a sulfur concentration of 0.01% by mass.

<Sulfurated copper powder 2>
The treatment was performed in the same manner as in the preparation of the sulfided copper powder 1 except that the sulfur concentration of the treatment solution was changed to 0.006 mass%, to obtain a powder having a sulfur concentration of 0.03 mass%.

<Sulfurated copper powder 3>
The treatment was performed in the same manner as in the preparation of the sulfurized copper powder 1 except that the sulfur concentration of the treatment solution was changed to 0.03 mass%, to obtain a powder having a sulfur concentration of 0.13 mass%.

<Sulfurated copper powder 4>
It processed similarly to preparation of the sulfurization-treated copper powder 1 except having changed the sulfur concentration of the process solution into 0.12 mass%, and obtained the powder whose sulfur concentration is 0.50 mass%.

<Sulfurated copper powder 5>
The treatment was performed in the same manner as in the preparation of the sulfided copper powder 1 except that the sulfur concentration of the treatment solution was changed to 0.54 mass%, to obtain a powder having a sulfur concentration of 2.75 mass%.

<Sulfurated copper powder 6>
It processed similarly to preparation of the sulfurization-treated copper powder 1 except having changed the sulfur concentration of the process solution into 0.75 mass%, and obtained the powder whose sulfur concentration is 6.90 mass%.

[Laser layer formation]
Using the above-mentioned sulfurized copper powder 1 to 5 and the copper powder before treatment as raw materials, using EOSINT M280 made by Germany EOS, under the nitrogen gas flow atmosphere (residual oxygen concentration about 0.5%), the following conditions A cylindrical shaped object having a diameter of 8 mm and a height of about 10 mm was produced.
Laser power: 370 W
Scanning speed: 200 to 1200 mm / sec Scanning pitch: 100 μm
Stacking thickness: 40 μm

  For the untreated copper powder, additive manufacturing was performed only at a scanning speed of 400 mm / sec. The sulfided copper powders 1 to 5 were subjected to additive manufacturing under conditions of a scanning speed of 200 mm / sec, 400 mm / sec, 600 mm / sec, 800 mm / sec, 1000 mm / sec, and 1200 mm / sec. The sulfided copper powder 5 (sulfur content: 2.75% by mass) could not produce a shaped article at a scanning speed of 200 mm / sec and 400 mm / sec.

[Evaluation]
<Observation of powder>
The surface shapes of the untreated copper powder and the sulfided copper powder 1 to 6 were observed with a scanning electron microscope (SEM) at a magnification of 500 times and 2000 times.

<Cross-sectional observation of layered object>
The cross section of the laminate was observed at 25 × and 50 × magnification by an optical microscope.

<Void ratio of layered object>
The cross section (near the center of a circle) of the layered object is observed with an optical microscope (magnification: 50 times), and the void ratio (%) = 100 × (void area) / (observation area) Calculated.

<Conductivity of Laminated Products>
The conductivity (% IACS) of the laminate was measured using an eddy current conductivity meter.

[Evaluation results]
Type of powder used to manufacture each layered object (sulfur concentration of ammonium sulfide aqueous solution used for processing and sulfur content of powder), scanning speed of layering, and evaluation results of layered object (porosity and conductivity) The ratio is shown in Table 1.

  The cross-sectional observation image of the laminate-molded article in the scanning speed of 200 mm / sec, 400 mm / sec, and 600 mm / sec of untreated copper powder and sulfurization-treated copper powder 1-5 is shown in FIG. Moreover, the SEM image of untreated copper powder and sulfurization-treated copper powder 1-6 is shown in FIG. The graph which plotted the sulfur content of the sulfided copper powders 1-4, and the porosity of the laminate-molded article in the scanning speed of 200 mm / sec and 400 mm / sec is shown in FIG.

  As shown in Table 1 and FIG. 1, in the case of the sulfided copper powders 1 to 4, as the laser scanning speed is smaller, the porosity of the laminate-molded product tends to be smaller and the conductivity to be higher. When the characteristics of the laminate-molded article are compared at the same laser scanning speed, as shown in FIG. 3, the porosity of the laminate-molded article is lower in the case of the sulfided copper powders 2 to 4 than in the case where the sulfided copper powder 1 is used. Is clearly reduced.

  As shown in FIG. 1, the layered product produced at a laser scanning speed of 200 mm / sec or 400 mm / sec using the sulfided copper powder 3 and the sulfided copper powder 4 has a significantly higher porosity than the other examples. Was reduced to The laminate-molded product produced at a laser scanning speed of 200 mm / sec using the sulfided copper powder 2 has a smaller porosity and higher conductivity than the laminate-molded product produced using the untreated copper powder. The other laminate-molded articles had a conductivity lower than that of the laminate-molded article using untreated copper powder, but all exhibited a conductivity of 30% IACS or more.

  The porosity of the laminate-molded product using the sulfurized copper powder 1 having a sulfur content of 0.01% by mass was equivalent to that of the laminate-molded product using the untreated copper powder. In the case of the sulfide-treated copper powder 1, the surface treatment of the copper powder is not sufficient, and it is considered that the void reduction effect of the layered product is not obtained because it has the same characteristics as the untreated copper powder.

  As shown in FIG. 2, the sulfurized copper powder 1 having a sulfur concentration of 0.01% by mass had a smooth surface, like the untreated copper powder. In the case of sulfurized copper powder 2 having a sulfur concentration of 0.03% by mass, fine irregularities are formed on the surface of the copper powder, and even with sulfurized copper powder 3 and 4, fine irregularities similar to those of sulfurized copper powder 2 are obtained. It was formed. In addition to the surface of the copper powder being sulfided by the ammonium sulfide treatment, the formation of fine irregularities reduces the light reflectance and increases the utilization efficiency of the light energy by the metal powder. It is considered to be one of the factors that can form a small shaped object.

  In the case of the sulfurized copper powder 5 having a sulfur concentration of 2.75% by mass, as compared with the sulfided copper powders 2 to 4, the surface asperity shape was coarsened, and particulate precipitates were observed. In the sulfurized copper powder 6 in which the sulfur concentration of the treatment solution was increased to a sulfur concentration of 6.90% by mass, the surface irregularities were further coarsened, and a crack was generated in the surface layer film. When the sulfur concentration of the powder is excessively high, it is presumed that such a change in the surface shape influences as a cause of the increase in the porosity in addition to the decrease in the conductivity of the layered product.

From the above results, it can be seen that metal powder containing a nonmetallic element such as sulfur can be obtained by surface treatment of copper powder. In addition, by using metal powder having a nonmetallic element content in a predetermined range as the material for laminating and forming, a laminate having a smaller porosity and higher density and higher conductivity than in the case of using pure copper can be obtained. I understand that.

Claims (11)

A metal powder for additive manufacturing,
Metal powder which contains one or more nonmetallic elements selected from the group consisting of sulfur, nitrogen and carbon in a total amount of 0.02 mass% or more and 90 mass% or more of copper.   The metal powder of Claim 1 which consists of said nonmetallic element, copper, 9 mass% or less oxygen, and an unavoidable impurity.   The metal powder according to claim 1 or 2 which contains sulfur as 0.02 mass% or more as said nonmetallic element.   The metal powder according to any one of claims 1 to 3, wherein the concentration of the nonmetallic element in the surface layer portion is higher than the concentration of the nonmetallic element in the central portion.   The metal powder of any one of Claims 1-4 which is an average particle diameter of 0.5-200 micrometers. It is a manufacturing method of the metal powder of any one of Claims 1-5, Comprising:
A method for producing a metal powder, comprising contacting the copper powder with a solution containing one or more nonmetallic elements selected from the group consisting of sulfur, nitrogen and carbon.   The manufacturing method of the metal powder of Claim 6 whose light reflectivity of metal powder becomes smaller than the light reflectivity of the said copper powder by contact with the said solution.   The method for producing a metal powder according to claim 6 or 7, wherein the surface area of the metal powder is larger than the surface area of the copper powder by the contact with the solution. A powder layer forming step of forming a powder layer containing the metal powder according to any one of claims 1 to 5; and irradiating energy at a predetermined position of the powder layer to solidify the metal powder to form a shaped layer Forming a forming process,
The manufacturing method of a laminate-molded article which repeats the said powder layer formation process and the above-mentioned modeling process one by one, and laminates the above-mentioned modeling layer.   The manufacturing of a laminate-molded article, wherein the step of supplying the heated melt of the metal powder according to any one of claims 1 to 5 to a predetermined position and solidifying it to form a shaped layer is repeated to laminate the shaped layer. Method. Containing at least 0.02 mass% in total, and at least 90 mass% of copper, containing one or more nonmetallic elements selected from the group consisting of sulfur, nitrogen and carbon;
A laminate-molded article having a porosity of 10% or less and a conductivity of 30% IACS or more as determined from cross-sectional observation.