Powder material, powder material for additive manufacturing, and method for manufacturing a powder material

Abstract

This invention provides a powder material that improves flowability and particle breakage strength compared to existing technologies. The powder material of this invention has a dendritic structure (1). The dendritic structure (1) has a superhard alloy composition or a cermet composition.

Description

[0001] This case is filed on the date of application. November 27, 2018 Application number is 201880071899.2 (PCT / JP2018 / 043475） A divisional application of the patent application entitled "Powder material, powder material for additive manufacturing and method for manufacturing powder material". Technical Field

[0002] This invention relates to, for example, powder materials for additive manufacturing, powder materials for additive manufacturing, and methods for manufacturing powder materials. Background Technology

[0003] In the prior art, the invention of the most suitable lamination molding particles and manufacturing method thereof is known (see Patent Document 1 below) for forming a lamination molding body (sintered body of WC-based superhard alloy) by irradiating WC-based superhard alloy particles of a specified thickness with electron beams to partially melt and solidify them.

[0004] The particles for laminated molding described in Patent Document 1 are formed by granulation and sintering of raw material powder for WC-based superalloys, and are used for laminated molding using electron beams. The average particle size is 60 to 130 μm and at least less than 150 μm, and the flowability is 10 to 25 sec / 50g as measured by JIS Z2502 (see claim 1 of Patent Document 1, etc.).

[0005] Furthermore, an invention relating to WC-based superhard alloys with high hardness, excellent high-temperature strength, and the ability to suppress deformation during manufacturing, and a method for manufacturing the same, is disclosed (see Patent Document 2 below).

[0006] In the WC-based superhard alloy described in Patent Document 2, tungsten carbide particles are bonded together using cobalt or a cobalt alloy. The hardness of this WC-based superhard alloy is 400–800 HV. Furthermore, the content of cobalt or a cobalt alloy in this WC-based superhard alloy is 35–50% by mass. Additionally, the average particle size of the tungsten carbide particles in the cross-sectional microstructure of this WC-based superhard alloy, in terms of the diameter of a circle, is 0.4–1.0 μm. Furthermore, the diameter of the largest inscribed circle of the region without tungsten carbide particles that can be drawn in the cobalt or cobalt alloy bonding phase in the cross-sectional microstructure of this WC-based superhard alloy is 5–30 μm (see claim 1 of Patent Document 2, etc.).

[0007] Furthermore, the manufacturing method described in Patent Document 2 is the manufacturing method of the aforementioned WC-based superhard alloy. In this conventional manufacturing method, a mixed powder of cobalt or cobalt alloy raw material powder with an average particle size D50 of 1 to 50 μm at a cumulative value of 50% and tungsten carbide raw material powder with a D50 of 0.4 to 1.0 μm attached to the surface is subjected to a curing treatment (see claim 2 of Patent Document 2, etc.).

[0008] Existing technical documents Patent documents Patent Document 1: Japanese Patent Application Publication No. 2016-172904 Patent Document 2: Japanese Patent Application Publication No. 2016-160500 Summary of the Invention

[0009] The technical problem that the invention aims to solve In the laminated molding particles described in Patent Document 1 and the mixed powder used in the manufacturing method of Patent Document 2, unevenness is formed on the surface of the particles or powder. Therefore, when these existing particles or mixed powders are used as materials for additive manufacturing, such as powder bed fusion, the low fluidity and uneven material distribution may lead to a decrease in the shape accuracy of the model produced by additive manufacturing.

[0010] Furthermore, in the aforementioned existing granular or mixed powders, there are issues with the bonding strength between cobalt (Co) and WC within the particles. Therefore, when using these existing granular or mixed powders as materials for the aforementioned additive manufacturing, the particles may be crushed during material laying.

[0011] This invention provides a powder material that improves flowability and particle breakage strength compared to existing technologies, a powder material for additive manufacturing, and a method for manufacturing the powder material.

[0012] Technical means for solving technical problems The powder material of the present invention is a powder material having a dendritic structure, wherein the dendritic structure is composed of a superhard alloy or a metal ceramic.

[0013] In addition, the powder material of the present invention is a powder material having a superhard alloy composition or a metal ceramic composition, and has a film containing more than 50 at% carbon on the outermost surface.

[0014] Invention Effects According to the present invention, a powder material, an additive manufacturing powder material, and a method for manufacturing the powder material are provided that can improve flowability and particle crushing strength compared with the prior art. Attached Figure Description

[0015] Figure 1A This is an enlarged photograph of the cross-section of the powder material according to Embodiment 1 of the present invention.

[0016] Figure 1B This is an enlarged photograph of the cross-section of the powder material according to Embodiment 1 of the present invention.

[0017] Figure 2A This is an enlarged photograph of the cross-section of the powder material according to Embodiment 2 of the present invention.

[0018] Figure 2B This is an enlarged photograph of the cross-section of the powder material according to Embodiment 2 of the present invention.

[0019] Figure 3 This is a magnified photograph of the powder material of Comparative Example 1.

[0020] Figure 4A This is an enlarged photograph of the cross-section of the powder material in Comparative Example 1.

[0021] Figure 4B This is an enlarged photograph of the cross-section of the powder material in Comparative Example 1.

[0022] Figure 5 This is an explanatory diagram illustrating some of the manufacturing processes of powder materials.

[0023] Figure 6A This is an enlarged photograph of the powder material involved in Embodiment 3 of the present invention.

[0024] Figure 6B It means Figure 6A A magnified photograph of the appearance of the particles of the first type of powder material shown.

[0025] Figure 6C It means Figure 6A A magnified photograph of the appearance of particles of the second type of powder material shown.

[0026] Figure 6D It means Figure 6A The image shown is a magnified photograph of the appearance of third-party particles of the powder material.

[0027] Figure 7A It means Figure 6B A magnified photograph of an example of the surface structure of particles of the first type shown.

[0028] Figure 7B It means Figure 6B A magnified photograph of an example of the surface structure of particles of the first type shown.

[0029] Figure 8A It means Figure 6B A magnified photograph of another example of the surface structure of particles in the first manner shown.

[0030] Figure 8B It means Figure 6B A magnified photograph of another example of the surface structure of particles in the first manner shown.

[0031] Figure 9A It means Figure 6C A magnified photograph of an example of the surface structure of particles in the second manner shown.

[0032] Figure 9B It means Figure 6C A magnified photograph of an example of the surface structure of particles in the second manner shown.

[0033] Figure 10 It means Figure 6D A magnified photograph of an example of the surface structure of third-party particles.

[0034] Figure 11 This is a photographic image showing an example of a particle cross-section of the powder material of Example 2 in a first manner.

[0035] Figure 12 This is a photographic image showing an example of a particle cross-section of the powder material of Example 2 in a second manner.

[0036] Figure 13A This is a photographic image showing an example of a cross-section of the powder material of Example 2 in a fourth manner.

[0037] Figure 13B This is a photographic image showing an example of a cross-section of the powder material of Example 2 in a fourth manner.

[0038] Figure 14A This is a TEM image of the powder material involved in the fourth method of the powder material in Example 2.

[0039] Figure 14B yes Figure 14A The image shown is a high-resolution TEM image of the outermost layer of the powder material particles.

[0040] Symbol Explanation 1: Dendritic tissue; 2: Ceramic particles; 300: Powder material; S1: Raw material preparation process; S2: Raw material mixing process; S3: Granulation process; S4: Firing process. Detailed Implementation

[0041] Hereinafter, embodiments of the powder material, additive manufacturing powder material, and powder material manufacturing method of the present invention will be described with reference to the accompanying drawings.

[0042] (Implementation Method 1) Figure 1A and Figure 1BThis is an enlarged photograph of the cross-section of the powder material according to Embodiment 1 of the present invention. Figure 1A The magnification of the photo is 1000x. Figure 1B The magnification of the photographs is 5000x. Specifically, the cross-section of powdered materials is observed by grinding resin into which the powder is embedded, exposing the cross-section of the particles on the resin surface.

[0043] The powder material of this embodiment has a dendritic structure 1. Powder is generally formed by the aggregation of particles, but here it sometimes refers to the particles constituting the powder. That is, the powder material of this embodiment includes particles having a dendritic structure 1. This dendritic structure 1 is, for example, a multi-branched dendritic crystal, i.e., a dendritic crystal (dentrite). Figure 1A and Figure 1B In the example shown, the bright, high-brightness portion of the particle cross-section is dendritic structure 1. This dendritic structure 1 has an ultrahard alloy composition or a cermet composition.

[0044] The powder material of this embodiment is, for example, composed of a dendritic structure having a superhard alloy composition or a cermet composition. Here, the superhard alloy composition of this embodiment is defined as containing W and carbon, with the remainder consisting of at least one selected from Fe, Ni, Co, and Cr. The cermet composition is defined as containing at least one of a Group 4 transition metal, a Group 5 transition metal, a Group 6 transition metal other than W, Al and Si, and at least one of oxygen, carbon, and nitrogen, with the remainder consisting of at least one selected from Fe, Ni, Co, and Cr. A preferred powder material composition contains at least one of W, Ti, and Si. The materials added to the powder material are either elemental metallic elements or compounds such as carbides, added to adjust the material composition of the powder material. There are no particular limitations on the materials added to the powder material.

[0045] The dendritic structure 1 of the powder material contains, for example, at least 5 at% of at least one selected from Group 4, Group 5, and Group 6 transition metals. There is no particular upper limit on the content of Group 4, Group 5, and Group 6 transition metals; for example, it can be set to 60 at% or less. The composition of the powder material can be determined, for example, using an X-ray photoelectron spectroscopy (XPS) apparatus.

[0046] Regarding the powder material of this embodiment, for example, the particle size (particle size distribution range) is 10 μm to 200 μm, and the flowability based on JIS Z 2502 is 25 sec / 50 g or less. With such a particle size range, the powder material can be sieved to achieve an appropriate average particle size. The particle size and particle size range of the powder material can be measured, for example, using a laser diffraction / scattering particle size distribution measuring device. In the JIS Z 2502-based test, the flowability of the powder material is evaluated by measuring the time it takes for 50 g of powder to pass through a funnel.

[0047] Furthermore, the particle size of the powder material is preferably 30 μm or more, more preferably 45 μm or more. And, more preferably, the upper limit of the particle size of the powder material is 130 μm.

[0048] The powder material of this embodiment can be used, for example, as a powder material for additive manufacturing. In other words, the powder material for additive manufacturing of this embodiment includes the powder material described above. Specifically, when the powder material for additive manufacturing contains, for example, 30 vol% or more, more preferably 40 vol% or more of the powder material of this embodiment, advantageous effects can be obtained during layer-by-layer molding. Additive manufacturing is a process of creating objects by attaching materials based on the numerical expression of the three-dimensional shape of the material. In most cases, it is achieved by stacking layers on top of each other, and is the opposite of the subtractive manufacturing method (ASTM F2792-12a). Additive manufacturing requires less finishing of the material and is a near-net-shape manufacturing process that can process it into a shape close to the final form.

[0049] The powder material for additive manufacturing in this embodiment can be used, for example, as a material for additive manufacturing using a powder bed fusion bonding method. Powder bed fusion bonding is a method that uses thermal energy to selectively fuse certain areas of a material powder. Examples of such methods include laser sintering, selective laser melting, and electron beam melting.

[0050] Figure 5 This is an explanatory diagram illustrating some steps of the method for manufacturing powder materials. The powder material of this embodiment is manufactured, for example, by a manufacturing method including the following steps. First, in the raw material preparation step S1, as raw materials, particles such as ceramic particles, particles of metal or alloy, and additives are prepared according to the composition of the powder material to be manufactured.

[0051] Here, the ceramic particles described above are selected from at least one oxide, carbide, nitride, carbon oxide, oxynitride, carbonitride, or carbonoxynitride selected from Groups 4, 5, and 6 transition metals, Si, and Al. Preferably, the ceramic particles are selected from at least one of tungsten carbide (WC), titanium carbide (TiC), silicon carbide (SiC), vanadium carbide (VC), alumina (Al₂O₃), titanium oxide (TiO₂), zirconium oxide (ZrO₂), silicon nitride (Si₃N₄), and aluminum nitride (AlN). Regarding the particle size of the ceramic particles, for example, the average particle size D₅₀ when the cumulative value is 50% is 5 μm or less, preferably 0.1 μm or more and 1.0 μm or less. Furthermore, the preferred metal or alloy particles are selected from at least one of Fe, Ni, Co, and Cr. The particle size of the metal or alloy particles is, for example, 1.0 μm or more and 50.0 μm or less as described above, and the particle size of the additive material is, for example, 0.1 μm or more and 1.0 μm or less as described above. Added materials include, for example, Be, B, Mg, Al, Si, Ti, Mn, Cu, Zn, etc.

[0052] Next, in the raw material mixing step S2, the raw materials prepared in the raw material preparation step S1 are wet-mixed with waxes such as paraffin wax. Next, in the granulation step S3, the mixture of raw materials and waxes mixed in the raw material mixing step is sprayed and dried using a spray dryer to granulate the mixture into particles.

[0053] Next, in the firing step S4, the powder 10 of the mixture granulated in the granulation step S3 is fed into a drying oven for degreasing, and then fired at a firing temperature of 1000°C or higher. The degreasing temperature is preferably 400°C to 600°C. The degreasing temperature is the temperature at which the wax used can be removed, and the firing temperature is the temperature at which the powder particles of the mixture are solidified.

[0054] The degreasing temperature and firing temperature in firing step S4 can be selected appropriately based on the combination of raw materials. By degreasing the powder 10 of the mixture in firing step S4, defects can be prevented during additive manufacturing. However, the degreased powder 10 of the mixture cannot be used directly for additive manufacturing because the powder particles are broken when the powder 10 is supplied. Therefore, in firing step S4, after heating to the degreasing temperature, the temperature is then raised to the firing temperature to solidify the powder particles of the mixture, and a high-temperature treatment step (not shown) is further performed after firing step S4.

[0055] In the high-temperature processing step, thermal plasma-droplet refining (PDR) is used to process the powder 10 of the mixture that has been solidified in the firing step S4, so that all or part of the powder particles are instantly melted and solidified.

[0056] Through the above processes, the powder material of this embodiment with dendritic structure 1 can be manufactured. In this way, the powder 10 of the mixture after the wax has been removed and solidified by the firing process S4 is heated instantly to melt and solidify it. As a result, due to surface tension, the particle shape of the powder material is formed into a near-spherical shape, and the particle surface becomes smooth.

[0057] In manufacturing the powder material of this embodiment having dendritic structure 1, during the high-temperature processing step, it is preferable to perform PDR (partial diaphragm reflow) under conditions where the powder of the mixture is melted at a high power of 10 kW to 40 kW. The lower limit of the input power during PDR is preferably 15 kW. More preferably, the power of PDR in the high-temperature processing step is set to 25 kW to 35 kW.

[0058] The functions of the powder material and the additive manufacturing powder material in this embodiment will be explained below.

[0059] As described above, the powder material of this embodiment has a dendritic structure 1. Furthermore, the dendritic structure 1 of the powder material has a superhard alloy composition or a cermet composition. Compared to conventional powder materials, this powder material with a dendritic structure 1 has fewer surface irregularities, a smooth particle surface, and a particle shape closer to a perfect spherical shape. Therefore, when the powder material of this embodiment, or the additive manufacturing powder material of this embodiment containing this powder material, is used in additive manufacturing, for example, by a powder bed fusion bonding method, higher flowability than conventional powder materials can be obtained, and the powder material can be laid more uniformly.

[0060] Furthermore, the powder material of this embodiment, which has a dendritic structure 1, and the additive manufacturing powder material containing this powder material, have a relatively uniform composition within the powder particles. Therefore, when manufacturing a model using additive manufacturing, the powder material can be melted uniformly, large fluctuations in the melt pool formed due to the melting of the powder material can be suppressed, and the formation of the melt pool can be stabilized. As a result, the shape accuracy of the model produced by additive manufacturing can be improved, and the surface can be smoothed. Therefore, the powder material and additive manufacturing powder material of this embodiment can achieve the excellent effect of manufacturing models with high precision using additive manufacturing.

[0061] On the other hand, existing material powders that do not have dendritic structure 1 form larger irregularities on the particle surface compared to the powder material of this embodiment. Therefore, when using existing material powders as materials for additive manufacturing, such as powder bed fusion bonding, the unevenness of the particle surface prevents the material powder from being evenly distributed, which may lead to a decrease in the shape accuracy of the model produced by additive manufacturing.

[0062] Furthermore, when using existing material powders composed of WC and Co phases as materials in additive manufacturing via powder bed fusion bonding, powders with different melting points fuse together during the process of melting the material powders to form a molten pool, subsequently forming a dendritic structure with a relatively uniform composition. Because this process occurs due to extremely short periods of heating and exothermic reactions, the additively manufactured shape exhibits compositional inhomogeneity in minute areas. This results in uneven sizes of the molten pools formed by melting the material powders, hindering the stable formation of the molten pools. Consequently, the additively manufactured shape suffers from reduced shape accuracy and surface unevenness.

[0063] Furthermore, existing powder materials have issues with the bonding strength between Co and WC particles. Therefore, if existing powder materials are used in additive manufacturing using the powder bed fusion bonding method described above, the powder particles may be pulverized during the powder bed application process. Moreover, using existing powder materials for sandblasting of the resulting additively shaped objects may also lead to particle pulverization. Thus, once the powder particles are pulverized, a problem of microparticle scattering occurs.

[0064] In contrast, the powder material of this embodiment exhibits improved particle strength compared to conventional powder materials due to its dendritic structure 1. More specifically, the dendritic structure 1 of the powder material is formed, for example, through a high-temperature and instantaneous melting and solidification process such as PDR. This process melts and solidifies all or part of the powder material particles, resulting in spherical particle shape and smoothed particle surfaces, as described above, while also increasing the particle breakage strength. Therefore, according to this embodiment, the flowability is improved compared to the prior art, enabling the provision of powder materials with improved particle breakage strength and powder materials for additive manufacturing.

[0065] Furthermore, the powder material in this embodiment has a superhard alloy composition or a cermet composition. Therefore, by using additive manufacturing methods such as powder bed fusion bonding, it is possible to make easier to manufacture molds and other shapes made of ceramic and metal materials.

[0066] More specifically, in the prior art, molds and other shapes composed of materials such as superhard alloys or cermet are manufactured, for example, by sintering ceramic and metal material powders. However, by using additive manufacturing powder materials containing powder materials of this embodiment composed of superhard alloys or cermet in additive manufacturing, it is possible to make the manufacture of shapes composed of materials such as superhard alloys or cermet easier and to increase the degree of freedom in shape. Cermet is a material formed by mixing powders of hard compounds such as metal carbides or nitrides with a metal binder.

[0067] Furthermore, the superhard alloy composition or cermet composition of the powder material in this embodiment preferably contains at least one of W, Ti, and Si, and carbon, with the remainder consisting of at least one selected from Fe, Cr, Ni, and Co. Therefore, as described above, the manufacture of molds and other shaped objects formed from materials having a superhard alloy composition or cermet composition is easier than in the prior art.

[0068] Furthermore, the superhard alloy composition or cermet composition of the powder material in this embodiment preferably contains at least 5 at% of at least one of Group 4 transition metals, Group 5 transition metals, Group 6 transition metals, and Si and Al, as well as at least 5 at% of at least one of oxygen, carbon, and nitrogen. Therefore, as described above, it is easier than prior art to manufacture molds and other shaped objects formed from materials having a superhard alloy composition or cermet composition and having a mixture containing at least 5 at% of the constituent elements of these ceramics.

[0069] Furthermore, the powder material of this embodiment has a particle size of 10 μm to 200 μm and a flowability of 25 sec / 50 g or less based on JIS Z 2502. The powder material of this embodiment possesses these characteristics, making it particularly suitable for use as a material in additive manufacturing using the powder bed fusion bonding method. When the particle size of the powder material is, for example, 45 μm or more, even when the powder material is used in additive manufacturing using the powder bed fusion bonding method with electron beam melting, it is possible to prevent the powder material from being ejected by the irradiation energy of the electron beam. Moreover, by making the particle size of the powder material, for example, 45 μm to 130 μm, a powder material suitable for additive manufacturing using the powder bed fusion bonding method with electron beam melting can be formed.

[0070] Furthermore, by setting the particle size of the powder material to, for example, 10 μm to 130 μm, it is possible to form powder materials suitable for additive manufacturing methods that use laser beams as heat sources for powder bed fusion bonding, such as laser sintering or selective laser melting. Moreover, by setting the particle size of the powder material to, for example, 30 μm to 200 μm, it is possible to form powder materials suitable for additive manufacturing using directional energy deposition methods.

[0071] As described above, according to this embodiment, it is possible to provide a powder material that improves flowability and particle breakage strength compared to the prior art, a powder material for additive manufacturing, and a method for manufacturing the powder material.

[0072] (Implementation Method 2) Figure 2A and Figure 2B This is an enlarged photograph of the cross-section of the powder material according to Embodiment 2 of the present invention. Figure 2AThe magnification of the photo is 1000x. Figure 2B The magnification of the photograph is approximately 5000 times.

[0073] The powder material of this embodiment comprises a dendritic structure 1 and ceramic particles 2 formed of ceramic components, which differs from the powder material described in Embodiment 1. Furthermore, the manufacturing method of the powder material of this embodiment is the same as that of the powder material of Embodiment 1, except for the heating conditions. It is generally considered that the powder material of this embodiment is easier to manufacture when the input power of the PDR is reduced. Other aspects of the powder material of this embodiment are the same as those of the powder material described in Embodiment 1, and therefore, descriptions of the similarities are appropriately omitted.

[0074] The powder material in this embodiment, like the powder material described in Embodiment 1, has a dendritic structure 1, which is composed of an ultrahard alloy or a metal-ceramic composition. The shape of the ceramic particles 2 is as follows: Figure 2A and Figure 2B As shown, various polygonal shapes are represented. More specifically, the dendritic structure 1 includes ceramic particles 2 of various polygonal shapes, such as triangles, quadrilaterals, and combinations thereof. Furthermore, the ceramic particles 2 are predominantly composed of ceramic microparticles prepared in the aforementioned raw material preparation process. Moreover, the superhard alloy composition or cermet composition of the dendritic structure 1 contains at least 5 at% of ceramic constituent elements.

[0075] The powder material according to this embodiment, like the powder material described in Embodiment 1, can provide a powder material with improved flowability and increased particle breakage strength compared to the prior art, and a powder material for additive manufacturing.

[0076] (Implementation Method 4) Figure 14A This is a cross-sectional transmission electron microscope (TEM) image of the powder material particles involved in Embodiment 4 of the present invention. Figure 14B yes Figure 14A High-resolution TEM image of the outermost layer of the particles shown. Figure 14A The magnification of the photo is 3000x. Figure 14B The magnification of the photo is 700,000 times.

[0077] Among them, Figure 14A and Figure 14B In the diagram, the upper side is the surface side of the particle, and the lower side is the center side of the particle. Figure 14A and Figure 14BThe sample of the particles shown was fabricated by forming a carbon protective film on the particle surface and then thinning it to a thickness of 100 nm using sputtering with a Ga ion beam.

[0078] The powder material in this embodiment is as follows: Figure 14A The powder material shown has a superhard alloy composition or a cermet composition, and has an outermost layer 3 on its outermost surface. This outermost layer 3 is a film containing 50 at% or more carbon. The carbon content of the outermost layer is preferably 60 at% or more, more preferably 70 at% or more. The composition of the protective film on the powder surface and the outermost layer 3 can be determined, for example, using energy dispersive X-ray spectroscopy (EDX). The manufacturing method of the powder material in this embodiment is the same as that of the powder material in Embodiment 1 described above. Other aspects of the powder material in this embodiment are the same as those described in Embodiment 1, and therefore, descriptions of the similarities are appropriately omitted.

[0079] In the powder material of this embodiment, the outermost layer 3 formed on the outermost surface of the particles is a film containing 50 at% or more carbon, and is a carbon-based film. The carbon content in the outermost layer 3, which is the carbon-based film on the particle surface, can be appropriately varied within the range of 50 at% or more, depending on the desired characteristics. For example, when it is desirable to further improve powder properties such as rolling characteristics, the carbon content is preferably 60 at% or more, more preferably 70 at% or more, even more preferably 80 at% or more, and particularly preferably 90 at% or more. Most preferably, the outermost layer 3 is composed of, for example, approximately 100 at% carbon.

[0080] like Figure 14B As shown, the outermost layer 3 of the film containing 50 at% or more carbon has, for example, a layered crystalline structure along the tangential direction of the surface. In this case, the powder material may have a dendritic structure 1 covered by the aforementioned film. The aforementioned superhard alloy composition or the aforementioned cermet composition, for example, contains at least one of a Group 4 transition metal, a Group 5 transition metal, a Group 6 transition metal, Si, and Al, and at least 5 at% or more carbon. The aforementioned superhard alloy composition or the aforementioned cermet composition may, for example, contain at least 5 at% or more oxygen or nitrogen, and the WC particles may be a composition formed by bonding with a Co or Co alloy bonding layer.

[0081] As described above, the powder material of this embodiment is a powder material composed of a superhard alloy or a cermet, and has an outermost layer 3 on its outermost surface, which is a film containing 50 at% or more carbon. The surface of the outermost layer 3 is smooth, thus reducing the coefficient of friction of the particle's outermost surface compared to the case without the outermost layer 3. Furthermore, compared to the case where the powder material does not have the outermost layer 3, the particle breakage strength of the powder material can be improved. Therefore, according to this embodiment, even when the powder material has an outermost layer 3, it is possible to provide a powder material and an additive manufacturing powder material that improves flowability and particle breakage strength compared to the prior art. The thickness of the outermost layer 3 is not particularly limited, and can be specified to be 20 nm to 5000 nm in order to stably exert the effect of the carbon film. In addition, the content of the powder material having the outermost layer 3 is preferably 50 vol% or more of the total additive manufacturing powder material, more preferably 60 vol% or more, further preferably 70 vol% or more, and particularly preferably 80 vol% or more, thereby enabling the aforementioned carbon film effect to be exerted.

[0082] Furthermore, in the powder material of this embodiment, when the outermost layer 3, which is a film containing 50 at% or more carbon, has a layered crystalline structure along the tangential direction of the surface, the coefficient of friction of the outermost surface of the particles can be further reduced, and the flowability of the powder material can be further improved. This can be attributed to the fact that, although the carbon atoms in the outermost layer 3, which is a film containing 50 at% or more carbon, are strongly covalently bonded to each other within the planes constituting each layer of the outermost layer 3, the interlayer bonding force is weak, resulting in interlayer splitting.

[0083] Furthermore, in the powder material of this embodiment, when the outermost layer 3 covers the dendritic structure 1 and the outermost layer is a film containing 50 at% or more carbon, as described above, higher flowability and higher particle strength can be achieved compared with conventional material powders.

[0084] Furthermore, when the powder material has an outermost layer 3, the dendritic structure can have a superhard alloy composition or a cermet composition as described above. This superhard alloy composition or cermet composition can contain at least one of a Group 4 transition metal, a Group 5 transition metal, a Group 6 transition metal, Si, and Al, and at least 5 at% carbon. Moreover, the superhard alloy composition or cermet composition can contain at least 5 at% oxygen or nitrogen, and the WC particles can be a composition formed by bonding with a Co or Co alloy bonding layer. Therefore, the manufacture of molds and other shaped objects made of materials having these compositions is easier than with existing technologies.

[0085] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the specific configuration is not limited to these embodiments. Any design changes that do not depart from the scope of the present invention are also included within the scope of the present invention. Hereinafter, embodiments of the powder material of the present invention and comparative examples as comparative objects will be described.

[0086] [Examples and Comparative Examples] Using the manufacturing method described in the above embodiments, the powder materials of Examples 1 to 3 were manufactured. Specifically, firstly, as raw materials, WC particles with an average particle size D50 of 0.4 μm to 1.0 μm and Co alloy particles with an average particle size D50 of 5 μm to 30 μm and Cr added to Co were prepared. Next, in the raw material mixing step, 2.0 mass% of the paraffinic compound n-tetradecane as a wax was added to the raw materials prepared in the raw material preparation step, and the mixture was mixed using a vertical ball mill.

[0087] Next, in the granulation process, a spray dryer is used to spray and dry the mixture of raw materials and wax from the raw material mixing process to produce granules. The composition of the granulated mixture powder is determined using an XPS analyzer, and the composition is Co 41 mass%, Cr 3.4 mass%, with the remainder being WC.

[0088] Next, in the firing process, the powder of the mixture particles obtained from the granulation process is fed into a drying furnace and degreased at a degreasing temperature of 500°C, followed by firing at a firing temperature of 1040°C. To improve the bonding strength of the powder particles, it is further fired at a firing temperature of 1260°C. Then, using PDR, the powder particles of the mixture fired in the firing process during the high-temperature treatment process are instantaneously melted and solidified to produce the powder materials of Examples 1 to 3 of this invention.

[0089] Regarding the powder material of Example 1, the input power of the PDR in the high-temperature treatment process was set to 15 kW, and it was manufactured under the following conditions: powder input of 100 g, treatment time of 37 minutes, plasma gas Ar: 76 L / min, H2: 3 L / min, carrier gas Ar: 4 L / min, and treatment pressure of 0.02 MPa. Regarding the powder material of Example 2, the input power of the PDR in the high-temperature treatment process was set to 18 kW. Regarding the powder material of Example 3, the input power of the PDR in the high-temperature treatment process was set to 25 kW. Furthermore, the powder of the mixture of particles after the firing process and before the high-temperature treatment process was used as the powder material of Comparative Example 1, constituting the comparative object of the powder materials of Examples 1 to 3.

[0090] Below, the flowability of the powder material of Comparative Example 1 and the powder materials of Examples 1 to 3 will be evaluated based on JIS Z 2502. Table 1 below shows the evaluation results of the flowability of the powder material of Comparative Example 1 and the powder materials of Examples 1 to 3.

[0091] [Table 1] As shown in Table 1, the flowability of the powder material in Comparative Example 1 exceeds 25 [sec / 50g], which is an unsuitable value for additive manufacturing using powder bed fusion bonding. However, the flowability of the powder materials in Examples 1-3 of this invention is below 25 [sec / 50g], specifically in the range of 10 [sec / 50g] to 12 [sec / 50g], which is a suitable value for additive manufacturing using powder bed fusion bonding.

[0092] Figure 3 This is a magnified photograph of the powder material 900 of Comparative Example 1, at a magnification of 500x. The powder material 900 of Comparative Example 1 exhibits a large degree of unevenness on its particle surface, resulting in deformed particle shapes with low sphericity and low surface smoothness. It can be considered that, given this particle state, the flowability of the powder material 900 of Comparative Example 1 is unsuitable for additive manufacturing using a powder bed fusion bonding method.

[0093] Next, the resin in which the powder material of Comparative Example 1 was embedded was ground to expose the cross-section of the particles, and the cross-sectional structure was observed using an electron microscope. Figure 4A and Figure 4B These are photographs of the particle cross-section of the powder material 900 of Comparative Example 1, at magnifications of 800x and 5000x, respectively. The powder material of Comparative Example 1 has ceramic particles c and metal particles m from the raw material in its cross-sectional structure, but does not have dendritic structure 1.

[0094] In addition, the powder materials of Examples 1 to 3 were observed using an electron microscope, and three different morphologies of particles as described below were found.

[0095] Figure 6A This is a magnified photograph of the powder material 300 of Example 3, with a magnification of 100x. Figure 6B This is a magnified photograph showing the appearance of the particles 301 of the first type contained in the powder material 300 of Example 3, with a magnification of 1000x. Figure 6C This is a magnified photograph showing the appearance of the particles 302 of the second type contained in the powder material 300 of Example 3, with a magnification of 1000x. Figure 6DThis is a magnified photograph showing the appearance of the third-party particles 303 contained in the powder material 300 of Example 3, at a magnification of 500x.

[0096] Figure 6A The powder material 300 of Example 3 shown contains Figure 6B The first type of particle 301 shown Figure 6C The second type of particles 302, and Figure 6D The three different forms of particles 303 shown are shown.

[0097] Figure 7A and Figure 7B It means Figure 6B An enlarged photograph of an example of the surface structure of particle 301 in the first manner shown. Figure 7A The magnification is 2000 times. Figure 7B The magnification of the photograph is 5000x. The particles 301 of the first embodiment have a dendritic structure 1. Although the dendritic structure 1 has a superhard alloy composition or a cermet composition, it does not have ceramic particles 2 composed of a ceramic composition. In the example shown, the particles 301 of the first embodiment not only have a dendritic structure 1, but also have an outermost layer 3 covering the dendritic structure 1.

[0098] The outermost layer 3 can be considered as a vitreous film formed, for example, by the melting and solidification of ceramic. The outermost layer 3 has linear portions 4 on its surface that form an irregular grid pattern. The linear portions 4 form an irregular polygonal network on the surface of the outermost layer 3, which is raised above other parts of the surface of the outermost layer 3, thereby forming wrinkles on the surface of the outermost layer 3.

[0099] Figure 8A and Figure 8B It means Figure 6B A magnified photograph of another example of the surface structure of particle 301 in the first manner shown. Figure 8A The magnification is 2000 times. Figure 8B The magnification of the photograph is 5000x. In the example image, the particles 301 of the first type not only have dendritic tissue 1, but also have tiny granular tissue 5, and an outermost layer 3 covering these granular tissue 5 and dendritic tissue 1.

[0100] In the microgranular structure 5, not only do individual structures have irregular polygonal shapes, but multiple granular structures 5 also form an irregular polygonal grid pattern, arranged along grain boundaries. This granular structure 5 can be considered to be formed, for example, by the nucleation growth of ceramic particles. In this example, the particles 301 of the first type also have... Figure 7A and Figure 7B The example shown has the same outermost layer 3 and linear portion 4.

[0101] Figure 6C The particles 302 of the second embodiment shown have a dendritic structure 1. The dendritic structure 1 has a superhard alloy composition or a cermet composition, and also has ceramic particles 2 formed by a ceramic structure. The ceramic particles 2 have a polygonal shape.

[0102] Figure 9A and Figure 9B It means Figure 6C The images shown are magnified photographs of an example of the surface structure of particles 302 in the second embodiment, at a magnification of 5000x. The surface structure of particles 302 in the second embodiment contains WC particles as ceramic particles 2 within the dendritic structure 1. A film-like substance is also observed on almost the entire powder surface of particles 302 in the second embodiment.

[0103] Figure 6D The third-party particle 303 shown has a microstructure in which fine ceramic particles 2 are dispersed in the metal. Figure 10 It means Figure 6D The image shown is a magnified photograph of an example of the surface structure of the third-party particle 303, at a magnification of 5000x. In the example shown, the surface structure of the third-party particle 303 has WC particles dispersed on the surface as fine ceramic particles 2, and grain boundary products 6 formed in the matrix.

[0104] Next, the composition of the powder material of Example 2 was determined using an XPS measuring device. More specifically, firstly, the resin in which the powder material of Example 2 was embedded was ground to expose the cross-section of the powder material particles.

[0105] Figure 11 A photograph of a cross-section of the particles of the first type contained in the powder material of Example 2 is shown, magnified 10,000 times. In the example, the powder material has a dendritic structure 1, and dark phases with low brightness in the secondary electron image (SEI) are present at the interfaces and interstices of the dendritic crystals. The compositional analysis results at the first measurement point P1, the second measurement point P2, and the third measurement point P3 in the figure are shown in Table 2 below.

[0106] [Table 2] The dendritic structure 1 at measurement point P1 is composed of Co-C-W-Cr. At measurement points P2 and P3, W and C decrease while Co increases at the interfaces and interstices of the dendritic crystals. From measurement point P1 to measurement point P3, that is, at dendritic structure 1, the interfaces and interstices of the dendritic crystals, there are 10 [at%] or more W and C as ceramic constituent elements. In other words, the chemical composition of dendritic structure 1 is a mixture of ceramic and metallic components.

[0107] Figure 12 This is a photographic image showing a cross-section of the particles of the second type contained in the powder material of Example 2, at a magnification of 10,000. In the example image, the powder material has a dendritic structure 1, in which WC particles, which are ceramic particles 2, are present. That is, the dendritic structure 1 contains ceramic particles 2 formed of a ceramic composition. In the example image, the powder material exhibits a dark phase with low brightness in the secondary electron image (SEI). The compositional analysis results at measurement points P4 (4th measurement point), P5 (5th measurement point), P6 (6th measurement point), and P7 (7th measurement point) in the figure are shown in Table 3 below.

[0108] [Table 3] In the second method, ceramic particles 2 at measurement point P4 (4th measurement point) showed a near 1:1 ratio of W and C, confirming them as WC particles. The difference in brightness of dendritic structure 1 was caused by the difference in W content. Following the order of brightness from high to low, W 21.0 [at%] and C 26.6 [at%] were detected at measurement point P5 (5th measurement point), and W 11.8 [at%] and C 29.9 [at%] were detected at measurement point P6 (6th measurement point). The W and C contents in dendritic structure 1 at these measurement points P5 and P6 were both above 10 [at%]. In the structure at measurement point P7 (7th measurement point), where the brightness was low due to the interstices of the dendritic crystals, 82.4 [at%] of Co was detected, indicating that the composition was predominantly metallic or alloyed.

[0109] Figure 13A and Figure 13B These are photographs illustrating an example of a cross-section of particles of the fourth type contained in the powder material of Example 2, magnified at 10,000x and 5,000x respectively. In the example shown, the powder material has WC particles as ceramic particles 2 within a Co-based matrix. The black structure in the figure represents free carbon 7. In the example shown, the powder material does not have a clearly defined dendritic structure 1, and the WC particles as ceramic particles 2 are more... Figure 3 , Figure 4A and Figure 4B The powder material of Example 1 shown is enlarged. Figure 13AThe compositional analysis results at measurement points P8 (8th measurement point) and P9 (9th measurement point) are shown in Table 4.

[0110] [Table 4] Figure 13A In the fourth method, at the high-brightness measurement point P8, the ceramic particles 2 showed W and C particles detected in an almost 1:1 ratio, confirming them as WC particles. Figure 13A In the fourth method, the microstructure at measurement point P9, where the particle brightness is low, showed 73.2 [at%] Co, with metal or alloy composition being the main component. The microstructures at measurement points P8 and P9 each contained more than 10 [at%] W and C.

[0111] Of these, the powder materials of Examples 1 to 3 could not be obtained by simply feeding the raw material powder into the plasma processing apparatus without manufacturing the powder material of Comparative Example 1. Therefore, it can be confirmed that the powder materials of Examples 1 to 3 of the present invention have a novel structure different from existing powder materials. Furthermore, when the input power (heating) in the PDR is increased, the proportion of particles in the first and second methods is higher than that in the third method.

[0112] Select particles having an outermost layer 3 from the powder material of Example 2 above (fourth method), such as Figure 14A , Figure 14B As shown, a TEM image was obtained. Figure 14A The magnification of the photo is 3000x. Figure 14B The magnification of the photograph is 700,000 times. Furthermore, EDX analysis was used to determine... Figure 14A The composition of the outermost layer 3 at measurement point P10 is shown. The compositional analysis results of the outermost layer 3 are shown in Table 5.

[0113] [Table 5] The results of EDX analysis confirm this. Figure 7A and Figure 7B , Figure 8A and Figure 8B ,as well as Figure 14A The powder material 300 of Example 3 shown contains particles 301 of the first type, which, as the outermost layer 3 of the outermost surface film, is a film containing 50 at% or more carbon, as shown in Table 5. Furthermore, according to... Figure 14B It can also be confirmed that it has a layered crystalline structure along the tangential direction of the surface, which can be expected to exhibit higher fluidity than existing powder materials.

Claims

1. A powder material for additive manufacturing, characterized in that, The additive manufacturing powder material contains a dendritic structure, the dendritic structure having a superhard alloy composition or a cermet composition, the superhard alloy composition or the cermet composition containing at least one of a group 4 transition metal, a group 5 transition metal, a group 6 transition metal and Si, Al, and at least 5 at% of oxygen, carbon and nitrogen, the powder material having a flowability of less than 12 sec / 50 g based on JIS Z 2502, and having a film containing more than 50 at% carbon on the outermost surface.

2. The powder material for additive manufacturing as described in claim 1, characterized in that, The powder material comprises dendritic structures and ceramic particles.

3. The powder material for additive manufacturing as described in claim 1, characterized in that, The ceramic particles are polygonal in shape.

4. The powder material for additive manufacturing as described in claim 1, characterized in that, The superhard alloy composition or the cermet composition contains at least 5 at% of at least one of oxygen, carbon, and nitrogen, and at least one of W, Ti, and Si, with the remainder being at least one selected from Fe, Cr, Ni, and Co.

5. The powder material for additive manufacturing as described in claim 1, characterized in that, The membrane has a layered crystalline structure along the tangential direction of its surface, and the membrane covers the dendritic tissue.

6. The powder material for additive manufacturing as described in claim 1, characterized in that, Particle size is 10μm or larger, up to 200μm.

7. The additive manufacturing powder material according to any one of claims 1 to 6, characterized in that, Particle size is 45μm or larger, up to 130μm.

8. A method for manufacturing an additive manufacturing powder material, used to manufacture the additive manufacturing powder material according to any one of claims 1 to 7, characterized in that the method comprises: A raw material mixing process involves wet mixing ceramic particles with an average particle size D50 of 0.4 μm to 1.0 μm, metal or alloy particles with an average particle size D50 of 5 μm to 30 μm, and wax to obtain a mixture. The mixture is sprayed and dried to produce granules. A firing process in which the powdered mixture is degreased and then fired at a firing temperature above 1000°C; and A high-temperature treatment process that involves refining the mixture particles with thermal plasma droplets, causing all or part of the powder to melt and solidify instantaneously after the solidification process in the firing step.

9. The method for manufacturing powder material for additive manufacturing as described in claim 8, characterized in that, The ceramic particles are selected from at least one oxide, carbide, nitride, carbon oxide, nitrogen oxide, carbon nitride, or carbon oxynitride selected from group 4, 5, and 6 transition metals, Si, and Al. The metal or alloy particles are selected from at least one of Fe, Ni, Co and Cr.

10. The method for manufacturing powder material for additive manufacturing as described in claim 8 or 9, characterized in that, The firing temperature is above 1040℃, and the power of the thermal plasma droplet refining is above 25kW and below 35kW.

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