Powder material for additive manufacturing

Abstract

To provide a powder material for lamination molding having excellent fluidity in a dynamic state.SOLUTION: A powder material for lamination molding comprises metal particles, has a powder dynamic friction angle of 22° or less and has an avalanche energy of 15 mJ / kg or less. The powder material for lamination molding preferably does not comprise a fluidization agent, ceramic particles or a binder made of an organic material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a powder material for additive manufacturing, and more particularly to a powder material containing metal particles that can be used as a raw material in an additive manufacturing method.

Background Art

[0002] As a new technology for manufacturing three-dimensional objects, the development of additive manufacturing technology (AM) has been remarkable in recent years. As a type of additive manufacturing technology, there is a layer manufacturing method that utilizes solidification by irradiating a powder material with an energy beam. As layer manufacturing methods using a metal powder material, two typical methods are a powder bed fusion method and a powder deposition method.

[0003] Specific examples of the powder bed fusion method include methods such as selective laser melting (SLM) and electron beam melting (EBM). In these methods, a powder material made of metal is supplied onto a base substrate to form a powder bed, and based on three-dimensional design data, an energy beam such as a laser beam or an electron beam is irradiated to a predetermined position on the powder bed. Then, the powder material at the irradiated site solidifies by melting and re-solidification, and a shaped object is formed. By repeating the supply of the powder material to the powder bed and the shaping by energy beam irradiation, and sequentially laminating the shaped objects in layers, a three-dimensional shaped object can be obtained.

[0004] On the other hand, as a specific example of the powder deposition method, laser metal deposition (LMD) can be mentioned. In this method, while injecting a metal powder using a nozzle at a position where a three-dimensional shaped object is to be formed, at the same time, irradiation with a laser beam is performed to form a three-dimensional shaped object having a desired shape.

[0005] When manufacturing a three-dimensional object made of a metal material using the layered manufacturing method as described above, the resulting three-dimensional object may have a structure in which the distribution of the constituent material is non-uniform, such as voids or defects. It is desirable to suppress the generation of such non-uniform structures as much as possible. In the layered manufacturing method using a metal material, there are multiple possible causes for the non-uniform distribution of the constituent material inside the manufactured three-dimensional object. One of the factors is that the state of the powder material before energy beam irradiation can have a significant impact on the state of the resulting three-dimensional object.

[0006] For example, in the powder bed fusion method, if the powder material can be smoothly supplied onto the substrate and a powder bed in which the powder material is evenly spread can be stably formed, and if the powder material can be filled at a high density in the powder bed, a three-dimensional object with high homogeneity is likely to be obtained after irradiating the powder bed with an energy beam. Also, in the powder deposition method, a three-dimensional object can be stably formed by smoothly and highly uniformly supplying the powder material from the nozzle. Thus, when manufacturing a three-dimensional object by the layered manufacturing method, the higher the fluidity of the powder material used as the raw material, the more it can promote the smooth supply and high-density filling of the powder material, and a three-dimensional object with high uniformity can be obtained after irradiating with an energy beam.

[0007] For example, Patent Document 1 discloses a modeling powder having an optimal powder fluidity range for use in powder bed fusion. The modeling powder of Patent Document 1 mainly consists of ceramic powder and binder powder and has a specified range of angle of repose, Hausner ratio (ratio of tapped density to loose density), and compressibility (((tapped density - loose density) / tapped density)×100). Here, the "loose density" corresponds to the apparent density defined in JIS Z 2504.

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0009] As described above, in the additive manufacturing method, from the viewpoint of manufacturing a high-quality three-dimensional object, it is important that the raw material powder has high fluidity. The angle of repose and Hausner ratio defined for the powder for forming in Patent Document 1 are parameters that mainly reflect the fluidity of the powder material in a static state. However, the additive manufacturing method includes many dynamic processes such as a process of spreading the powder material (squeezing process). Therefore, in order to manufacture a high-quality three-dimensional object having a dense and highly uniform structure, it is important that the raw material powder has high fluidity in a dynamic state. The high fluidity in a static state does not necessarily correspond to the high fluidity in a dynamic state.

[0010] The problem to be solved by the present invention is to provide a powder material for additive manufacturing having excellent fluidity in a dynamic state.

Means for Solving the Problems

[0011] In order to solve the above problems, the powder material for additive manufacturing according to the present invention contains metal particles, has a powder dynamic friction angle of 22° or less, and an avalanche energy of 15 mJ / kg or less.

[0012] Here, the powder material for additive manufacturing preferably does not contain a fluidizing agent. Further, the powder material for additive manufacturing preferably does not contain ceramic particles. The powder material for additive manufacturing preferably does not contain a binder made of an organic material.

Effects of the Invention

[0013] The powder material for laminated manufacturing according to the above invention has a powder dynamic friction angle and an avalanche energy that are each suppressed below a predetermined upper limit. Both the powder dynamic friction angle and the avalanche energy are indicators showing the height of fluidity in the dynamic state of the powder, and the smaller these values are, the better the powder material is in terms of dynamic fluidity. Therefore, the powder material for laminated manufacturing according to the above invention is excellent in dynamic fluidity, and in each process included in laminated manufacturing, processes involving dynamic flow of the powder material, such as the spreading process, can be smoothly and highly uniformly advanced. As a result, it becomes a raw material powder that can provide a three-dimensional shaped object having a highly uniform structure by laminated manufacturing.

[0014] Here, in the above powder material for laminated manufacturing, by suppressing the powder dynamic friction angle and the avalanche energy below a predetermined upper limit, the fluidity can be sufficiently increased. Therefore, for the purpose of improving fluidity, there is no need to contain a fluidizing agent. By making the powder material for laminated manufacturing not contain a fluidizing agent, in the three-dimensional shaped object manufactured using the powder material for laminated manufacturing, the influence of the substance introduced as the fluidizing agent can be eliminated.

[0015] Also, metal particles have a larger Hamaker constant and a larger van der Waals force acting between particles than ceramic particles, so the fluidity is lower. However, in the powder material for laminated manufacturing according to the above invention, even when not containing ceramic particles, by having a powder dynamic friction angle and an avalanche energy suppressed below the above upper limit, sufficiently high dynamic fluidity can be ensured.

[0016] When the powder material for laminated manufacturing does not contain a binder made of an organic material, the dynamic fluidity of the powder material for laminated manufacturing can be increased without being affected by the binder. Also, in the three-dimensional shaped object manufactured using the powder material for laminated manufacturing, the formation of defects due to the presence of organic substances is suppressed. Therefore, by increasing the dynamic fluidity of the raw material powder, the effect of improving the uniformity of the structure of the manufactured three-dimensional shaped object is less likely to be impaired by the occurrence of defects.

Brief Description of the Drawings

[0017]

Figure 1

Mode for Carrying Out the Invention

[0018] Hereinafter, a powder material according to an embodiment of the present invention will be described in detail. In this specification, for a certain component, the states of "not containing" and "not being contained" shall include not only the state where the component is not contained at all, but also the state where the component is contained as an inevitable impurity.

[0019] The powder material for laminated manufacturing according to an embodiment of the present invention (hereinafter, may be simply referred to as a powder material) contains metal particles, has a powder dynamic friction angle of 22° or less, and an avalanche energy of 15 mJ / kg or less. The powder material for laminated manufacturing according to this embodiment has such a powder dynamic friction angle and avalanche energy, and thus has high dynamic fluidity.

[0020] [Constituent Materials] The powder material according to this embodiment contains metal particles. Here, the metal particles refer to particles composed only of metal, excluding inevitable modifications such as surface oxidation and the inclusion of inevitable impurities such as raw material residues. The metal species constituting the metal particles is not particularly limited, but examples of metal species that can be suitably used as raw materials for laminated manufacturing include iron-based alloys such as stainless steel, nickel-based alloys, titanium-based alloys, and cobalt-based alloys. In particular, it is preferable to use an iron-based alloy or a nickel-based alloy in terms of providing a three-dimensional shaped object with excellent properties such as hardness after the laminated manufacturing process. The powder material may contain only one kind of particle or two or more kinds of particles as the metal particles.

[0021] The particle size of the metal particles is not particularly limited, but from the viewpoint of being suitably used as a raw material for additive manufacturing, it preferably has a particle size on the micron order. Specifically, the particle size of the metal particles can be 10 μm or more and 500 μm or less in terms of the average particle size (d50). If the average particle size is 10 μm or more and 100 μm or less, it is particularly preferable. Note that the average particle size (d50) refers to the particle size at which the cumulative undersize fraction in the mass-based distribution is 50%.

[0022] The powder material according to the present embodiment may be composed only of metal particles excluding inevitable impurities, or may contain other substances in addition to the metal particles. As substances other than the above-mentioned micron-order metal particles that can be added to the powder material, nanoparticles can be exemplified. The nanoparticles are interposed between adjacent metal particles and ensure a distance between the metal particles, thereby reducing the attractive forces acting between the metal particles, such as van der Waals forces and electrostatic attractive forces. As a result, the fluidity of the powder material composed of metal particles can be enhanced.

[0023] The nanoparticles are not particularly specified in terms of the type or specific particle size as long as they have a particle size on the nanometer order, but cases where the particle size is 1 nm or more and 100 nm or less can be exemplified as preferable. The nanoparticles may be made of a metal or a metal compound, but from the viewpoint of effectively reducing the attractive force between the metal particles, it is preferable that they are made of a metal compound. Examples of the metal compound include metal oxides, metal nitrides, and metal carbides. Among them, from the viewpoints of low activity and ease of obtaining the nanoparticles, etc., it is preferable that they are metal oxides. The metal species constituting the metal compound is not particularly limited, but a form using light metal elements such as Si, Al, and Ti is preferable. Nanoparticles of oxides (such as SiO2, Al2O3, and TiO2) of these elements are less likely to have a profound impact even if they are contained in a three-dimensional shaped object made of metal through the additive manufacturing process. In particular, it is preferable to use an oxide of Si (silica) as the nanoparticles. As the nanoparticles, only one type may be used, or two or more types may be mixed.

[0024] The nanoparticles may be composed only of the main material, such as metal oxides, excluding inevitable impurities, but it is preferable that they are surface-treated. Suitable surface treatments include hydrophobization treatment. Examples of hydrophobization treatment include surface modification with organic molecules such as silane coupling agents. By hydrophobization treatment, aggregation between nanoparticles due to adsorption of water molecules and hydroxyl groups, and thereby reduction in the fluidity of the powder material can be suppressed. Also, the nanoparticles may be dispersed independently of the metal particles or attached to the surface of the metal particles in the powder material. The content of the nanoparticles in the powder material is not particularly limited, but examples of the range are 0.001% by mass or more and 0.1% by mass or less based on the mass of the metal particles.

[0025] It is preferable that the powder material according to this embodiment does not contain components other than the metal particles, which are the main material, and the nanoparticles, excluding inevitable impurities. Examples of substances that are better not to be contained in the powder material include fluidizing agents. A fluidizing agent is a substance that can improve the fluidity of a powder composed of metal particles when mixed therewith, and is composed of particles of metal compounds or the like. Representative fluidizing agents include oxide particles of metals such as Si, Ti, and Al. Since the powder material according to this embodiment has a sufficiently high fluidity by having a powder dynamic friction angle and an avalanche energy below a predetermined upper limit, there is no need to add a fluidizing agent for the purpose of improving fluidity. By not adding a fluidizing agent, in a three-dimensional shaped object formed using the powder material, a situation where a substance added to the powder material as a fluidizing agent acts as an impurity can be avoided. Note that the nanoparticles described above are not included in the fluidizing agent.

[0026] In addition to those that function as fluidizing agents, the powder material according to the present embodiment preferably does not contain ceramic particles. Although ceramic particles are also used as raw materials for laminated fabrication, the powder material according to the present embodiment is assumed to be used as a raw material for forming a metal member by laminated fabrication, and thus preferably does not contain ceramic particles. Generally, since metal particles have a larger Hamaker constant than ceramic particles and the van der Waals force acting between the particles becomes larger, the fluidity of the powder material tends to be low. However, in the powder material according to the present embodiment, even if the substance contained as particles having a particle size on the micron order is only metal particles, the powder dynamic friction angle and the avalanche energy are controlled within the above ranges, so that it exhibits high dynamic fluidity. Note that the ceramic particles, which are substances that are preferably not contained in the powder material here, do not include the metal compounds as the nanoparticles described above. This is because nanoparticles have a small volume and are unlikely to affect the properties of the metal of the member even if they are contained in the manufactured metal member.

[0027] Furthermore, as a substance that should preferably not be contained in the powder material according to the present embodiment, a binder made of an organic material can be cited. The binder assists in forming a three-dimensional shaped object by solidifying the powder material in the laminated shaping process, but may also affect the fluidity of the powder material. By not including the binder in the powder material, it is possible to avoid the influence on the fluidity realized by the metal particles and the optionally added nanoparticles. In addition, an organic material such as a binder can form pores in the three-dimensional shaped object due to the generation of hydrocarbon-based gas in the laminated shaping process, which can cause a non-uniform distribution of the structure. The powder material according to the present embodiment has high dynamic fluidity, and thus has the effect of enhancing the homogeneity of the structure in the three-dimensional shaped object manufactured through the laminated shaping process. By avoiding a decrease in the structural homogeneity due to the formation of defects caused by the inclusion of organic substances, this effect can be enhanced. Note that ceramics materials and organic materials are preferably not contained in the powder material except for inevitable impurities, even in forms other than independent particles or binders. For example, the surface of the metal particles is preferably not coated with a layer other than the intended metal material, such as a layer of a metal compound like a ceramics layer or a layer of an organic substance, and the metal surface is preferably exposed. When the nanoparticles are hydrophobically treated, since the amount of organic molecules used for the hydrophobic treatment is extremely small corresponding to the small volume of the nanoparticles, it does not substantially affect the manufactured three-dimensional shaped object.

[0028] In the powder material according to this embodiment, as a suitable means for improving fluidity, particularly the dynamic fluidity manifested as small powder dynamic friction angle and avalanche energy, the addition of nanoparticles such as the metal oxides described above can be mentioned. Additionally, as an effective means for improving the fluidity of the powder material, as metal particles, those having a high roundness, a shape approximating a sphere, and a smooth surface can be used. As a method for improving the roundness of metal particles, for metal powders produced by an atomization method or the like, means such as eliminating aggregation by applying a shearing force, selecting a particle size distribution by classification, and causing surface melting by plasma heating or the like can be exemplified. Also, from the perspective of avoiding the inclusion of materials other than the metal material as described above, it is better not to provide a layer of a metal compound such as a ceramic material or a layer of an organic material on the surface of the metal particles. However, from the perspective of improving fluidity, a layer of an inert metal compound such as a metal oxide or a metal nitride, or a layer of a hydrophobic substance such as an organic material may be provided on the surface of the metal particles. Also, drying the powder material and reducing the moisture content are also effective in improving fluidity.

[0029] [Powder dynamic friction angle] In the powder material according to this embodiment, the powder dynamic friction angle is suppressed to 22° or less. The powder dynamic friction angle can be obtained from the critical state line (CSL) by a shear test based on JIS Z 8835. Specifically, while applying a vertical stress (stress perpendicular to the shear plane) to the powder material filled in two cells, the shear stress generated between the powder materials filled in the two cells is measured. Then, after obtaining the critical state line as the relationship between the shear stress when a certain value is reached and the vertical stress acting on the shear plane, the angle formed by the critical state line and the vertical stress axis can be taken as the powder dynamic friction angle.

[0030] The smaller the powder dynamic friction angle, the smaller the shear stress acting on the powder material, indicating that the fluidity of the powder material is high. As the fluidity of the powder material, there are two types of contributions: static fluidity indicating the fluidity in a static state where the powder material is constrained and not flowing, such as when filled in a container, and dynamic fluidity indicating the fluidity in a dynamic state where the powder material flows without being constrained. The powder dynamic friction angle mainly reflects the dynamic fluidity among these. The acquisition of the limit state line for evaluating the powder dynamic friction angle corresponds to applying a shear force by translational motion or rotational motion between the layers of the powder material filled in two cells. In particular, when the particles constituting the powder material have a high roundness and a smooth surface, making it difficult for shear stress to act between the particles, this is well reflected in the smallness of the powder dynamic friction angle.

[0031] The powder material according to this embodiment has a high dynamic fluidity suitable as a raw material powder for laminated manufacturing because its powder dynamic friction angle is 22° or less. It is more preferable that the powder dynamic friction angle is 19° or less. Although there is no particular lower limit for the powder dynamic friction angle of the powder material, from the viewpoint of facilitating the spreading of the powder material on the powder bed, it may be set to, for example, 10° or more.

[0032] [Avalanche Energy] The powder material according to this embodiment has an avalanche energy of 15 mJ / kg or less. The avalanche energy (AE) is a parameter indicating the change in the potential energy of the powder material accompanying the avalanche phenomenon. When the rotating drum containing the powder material is rotated, the avalanche energy can be evaluated as the change in potential energy before and after the avalanche phenomenon in which the powder material pulled upward with the rotation collapses.

[0033] The smaller the avalanche energy, the easier it is for the aggregated powder material to collapse. That is, the smaller the avalanche energy, the higher the fluidity of the powder material is shown. Since the avalanche energy is evaluated while rotating a rotating drum containing the powder material and flowing the powder material, it well reflects the dynamic fluidity of the powder material. In particular, when the adhesiveness of the powder material due to attractive forces acting between particles, such as van der Waals forces and electrostatic attractive forces, is small, this is well reflected as the smallness of the avalanche energy.

[0034] In the powder material according to the present embodiment, since the avalanche energy is 15 mJ / kg or less, the powder material has high dynamic fluidity suitable as a raw material powder for additive manufacturing. It is more preferable that the avalanche energy is 10 mJ / kg or less. Although there is no particular lower limit provided for the avalanche energy of the powder material, from the viewpoint of facilitating the spreading of the powder material on the powder bed, it is advisable to set it, for example, at 5 mJ / kg or more.

[0035] [Properties of Powder Material] The powder material according to the present embodiment has a powder dynamic friction angle suppressed to 22° or less and an avalanche energy suppressed to 15 mJ / kg or less. Since the powder dynamic friction angle and the avalanche energy are suppressed to be so small, the powder material according to the present embodiment is excellent in fluidity, particularly dynamic fluidity. Furthermore, the high dynamic fluidity reflects both the smallness of the shear stress generated between particles and the low adhesiveness of the particles. Since the powder material containing metal particles has high dynamic fluidity, the powder material can be suitably used as a raw material for additive manufacturing.

[0036] Many of the processes for performing additive manufacturing involve dynamically flowing a powder material. For example, when implementing powder bed fusion methods such as SLM or EBM among additive manufacturing methods, a powder material is supplied from a hopper, spread over a substrate, and a powder bed is formed. At this time, due to the high fluidity of the powder material, the powder material can stably flow out from the hopper. Also, when using a recoater or the like to spread the powder material to form a powder bed (skidding), it becomes easier to spread the powder material densely and homogeneously. Thus, the high dynamic fluidity of the powder material is important for stably forming a highly uniform and dense powder bed. Then, by irradiating an energy beam onto a powder bed with high uniformity and density and performing additive manufacturing, it becomes easier to form a three-dimensional object with high tissue uniformity, high density, and few defects. Also, in additive manufacturing by powder deposition methods including LMD, by using a powder material with excellent dynamic fluidity, the powder material can be stably supplied to the nozzle. Further, when injecting the powder material together with an air current toward the location where manufacturing is performed from the nozzle, the supply of the powder material can be continued with high uniformity, and manufacturing can proceed stably. Note that as the apparatus for performing additive manufacturing, in the examples, a product of Concept Laser is used, but the powder material according to this embodiment can be suitably used for performing additive manufacturing not only with this product but also with various additive manufacturing apparatuses.

Examples

[0037] Hereinafter, the present invention will be described more specifically using examples. Here, regarding various powder materials, the relationship between the powder dynamic friction angle and the avalanche energy and the compatibility with additive manufacturing was examined. The present invention is not limited by the following examples.

[0038] (Preparation of Samples) A plurality of powder materials containing metal particles made of iron-based alloys and nickel-based alloys were prepared. Except for the powder material marked "with nano" in Figure 1, the powder materials contain only those metal particles, excluding inevitable impurities. The powder material marked "with nano" contains SiO2 nanoparticles in addition to particles made of metal. In any of the powder materials, the particle size of the metal particles is in the range of 14 μm or more and 50 μm or less in average particle size. Also, in the powder material with "nano", the particle size of the nanoparticles is in the range of 12 nm or more and 15 nm or less, and the addition amount of the nanoparticles is in the range of 0.01 mass% or less based on the mass of the metal particles.

[0039] (Evaluation of powder dynamic friction angle) In accordance with JIS Z 8835, using a rotational cell type shear test apparatus, the powder dynamic friction angle of each powder material was evaluated. The relationship between the shear stress acting on the shear plane between the powder materials filled in the two cells and the vertical stress acting on the shear plane was plotted with the shear stress on the vertical axis and the vertical stress on the horizontal axis, and a limiting state line was obtained as an approximate straight line passing through the origin. Then, the powder dynamic friction angle was determined as the angle formed by the limiting state line and the horizontal axis. The evaluation of the powder dynamic friction angle was carried out at room temperature in an environment with a humidity of 15%RH.

[0040] (Evaluation of avalanche energy) Using a rotary drum type powder flowability measuring apparatus, the avalanche energy of each powder material was evaluated. The powder material was accommodated in a transparent rotary drum, and while rotating at a rotational speed of 0.6 rpm, the state of the powder was photographed from the outside of the rotary drum, and the height of the powder surface based on the bottom of the drum was recorded. Then, the difference in the total potential energy of the powder material before and after the avalanche phenomenon occurred was taken as the avalanche energy. Here, the total potential energy of the powder material was estimated by calculating the potential energy based on the bottom of the drum for each pixel of the photographed image and taking the sum. The evaluation of the avalanche energy was carried out at room temperature in an environment with a humidity of 5%RH or less.

[0041] (Evaluation of suitability for additive manufacturing) The compatibility of each powder material with laminated manufacturing was evaluated by performing laminated manufacturing using SLM. Specifically, after each powder material was supplied from a hopper onto a substrate, a recoater was used to spread the powder material on the substrate to form a powder bed. Then, a laser beam was irradiated onto the powder bed to form a shaped object. By alternately repeating the spreading of the powder material and the irradiation of the laser beam, a three-dimensional shaped object was formed. The conditions for laminated manufacturing were as follows. · Apparatus used: "M2" manufactured by Concept Laser · Laser beam used: wavelength 1070 nm, energy density 60 - 100 J / mm 3 · Thickness of the layer of powder material spread at one time: 50 μm · Shape of the formed three-dimensional shaped object: block shape (12 mm × 12 mm × 12 mm)

[0042] Samples for which the supply of the powder material from the hopper or the spreading of the powder material by the recoater could not be performed smoothly were evaluated as impossible to laminate manufacture (×). This can be interpreted as being due to the extremely low fluidity of the powder material, resulting in the inability to normally discharge the powder material from the hopper or disperse the powder material by the recoater. For samples for which the formation of the powder bed could be performed without problems, the formed three-dimensional shaped object was cut at the center, and based on the captured image of the cross-section, it was evaluated whether or not shape unevenness (non-uniform distribution of constituent materials) was formed in the cross-section. Specifically, the captured image was binarized, and the area ratio of the region occupied by the metal material was estimated. Samples for which the area ratio of the region occupied by the metal material was 99.9% or less and shape unevenness was considered to have occurred were evaluated as having low compatibility with laminated manufacturing (△). On the other hand, samples for which the area ratio of the region occupied by the metal material exceeded 99.9% and shape unevenness was not considered to have occurred were evaluated as having high compatibility with laminated manufacturing (○). It can be interpreted that when the fluidity of the powder material is high, a highly uniform structure without shape unevenness is formed.

[0043] (Evaluation results) Figure 1 shows the relationship between the powder dynamic friction angle, the avalanche energy, and the suitability for laminated manufacturing for each powder material. The powder dynamic friction angle is plotted on the vertical axis, the avalanche energy is plotted on the horizontal axis, and the suitability for laminated manufacturing is indicated by plot symbols. As plot symbols, those with high suitability for laminated manufacturing (〇) are shown as circles, those with low suitability for laminated manufacturing (△) are shown as triangles, and those for which laminated manufacturing was impossible (×) are shown as crosses. Further, when the metal particles are composed of an iron-based alloy, each symbol is shown in black, and when the metal particles are composed of a nickel-based alloy, each symbol is shown in gray. Also, when nanoparticles are added to the powder material, each symbol is shown in white. However, for each material type, not all data points of "〇", "△", and "×" exist.

[0044] According to Figure 1, as shown by the dashed line in the figure, data points of samples with high suitability for laminated manufacturing, indicated by circles, are distributed in the region where the powder dynamic friction angle is 22° or less and the avalanche energy is 15 mJ / kg or less. On the other hand, outside that region, data points of samples with low suitability for laminated manufacturing, indicated by triangles, and samples for which laminated manufacturing was impossible, indicated by crosses, are distributed. From this, it can be seen that by using a powder material with a powder dynamic friction angle of 22° or less and an avalanche energy of 15 mJ / kg or less, the supply and spreading of the powder material can be smoothly performed, and high dynamic fluidity can be obtained, which provides a three-dimensional shaped object with high tissue uniformity. If a threshold is set for only one of the powder dynamic friction angle and the avalanche energy, it is not possible to accurately select a powder material having high dynamic fluidity and excellent suitability for laminated manufacturing. It is only possible to select a powder material having high fluidity suitable as a raw material for laminated manufacturing by using both parameters as indices.

[0045] Furthermore, in FIG. 1, there is a tendency that powder materials within the region of a powder dynamic friction angle of 22° or less and an avalanche energy of 15 mJ / kg or less exhibit high compatibility with laminated forming, while powder materials outside that region have low compatibility with laminated forming or are incapable of laminated forming. This tendency is commonly observed regardless of whether the metal particles are composed of an iron-based alloy, a nickel-based alloy, or whether nanoparticles are added. From this, regardless of the detailed material composition of the powder material, such as the type of metal constituting the powder material and the presence or absence of nanoparticles, by selecting a powder material to be used as a raw material for laminated forming with the powder dynamic friction angle and the avalanche energy as indices, and ensuring that their respective values are 22° or less and 15 mJ / kg, it can be said that a high-quality three-dimensional formed object with high tissue uniformity can be formed by utilizing the high dynamic fluidity of the powder material.

[0046] As described above, the embodiments and examples of the present invention have been explained. The present invention is not particularly limited to these embodiments and examples, and various modifications can be made.

Claims

1. A powder material for laminated manufacturing, containing metal particles composed of an iron-based alloy or a nickel-based alloy, not containing nanoparticles composed of oxides of Si, Al, and Ti, having a powder dynamic friction angle of 22° or less, and having an avalanche energy of 15 mJ / kg or less.

2. A powder material for laminated manufacturing, containing metal particles with a particle size in the range of 14 μm or more and 50 μm or less in terms of average particle size, not containing nanoparticles composed of oxides of Si, Al, and Ti, having a powder dynamic friction angle of 22° or less, and having an avalanche energy of 15 mJ / kg or less.

3. The powder material for laminated manufacturing according to Claim 1 or Claim 2, not containing a fluidizing agent.

4. The powder material for laminated manufacturing according to Claim 1 or Claim 2, not containing ceramic particles.

5. The powder material for laminated manufacturing according to any one of Claims 1 to 4, not containing a binder made of an organic material.

6. The powder material for laminated manufacturing according to Claim 1, wherein the particle size of the metal particles is in the range of 14 μm or more and 50 μm or less in terms of average particle size.

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