Powder for laminated molding and laminated molded article

Abstract

To provide a powder for laminated molding that is capable of forming a powder layer with good fillability and high penetration of an aqueous binder solution, and allows efficient production of a laminated molded article with high shape accuracy, and to provide a laminated molded article with high shape accuracy.SOLUTION: A powder for laminated molding used for producing a laminated molded article by a binder jetting method, comprises: a metal particle; and a coating disposed on the surface of the metal particle and containing a compound originating from a silane coupling agent, wherein the silane coupling agent is constituted by structural units represented by the following formula (1). [In formula (1), R represents functional groups which are independent from each other, 50% or more of the functional groups R being organic groups containing any one of a carboxyl group, a hydroxyl group, an amino group, or an epoxy group. n represents the number of repeating units, and is 0 or more and 10 or less.]SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention relates to a powder for additive manufacturing and an additive manufactured product. [Background technology]

[0002] In recent years, additive manufacturing methods using metal powder have become increasingly popular as a technology for creating three-dimensional objects. One such additive manufacturing method is the binder jet method.

[0003] Patent Document 1 discloses a solid freeform fabrication system that uses inkjet printing technology to eject droplets of different volumes as binder droplets onto a powder layer, solidifying the powder and creating an object. Because the method for manufacturing an object using such a system includes a step of ejecting binder droplets, it can be considered a type of binder jetting. By ejecting droplets of different volumes, such a system can produce an object with a smooth surface finish.

[0004] Furthermore, Patent Document 2 discloses the use of powder for additive manufacturing in binder jetting, in which a cyclic structure-containing group, a fluoroalkyl group, or a fluoroaryl group is introduced to the particle surface of a metal powder. The introduction of such functional groups allows for the production of powder for additive manufacturing with high fluidity, resulting in a powder layer with a high packing ratio. By increasing the packing ratio of the powder layer, an additive manufacturing object with high shape precision can ultimately be obtained. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2006-515813 [Patent Document 2] Japanese Patent Publication No. 2022-122503 Summary of the Invention [Problem to be solved by the invention]

[0006] In the binder jet method, a water-based liquid (water-based binder solution) is often used as the binder droplets. The water-based binder solution penetrates into the powder layer, solidifying that area.

[0007] However, the powder for additive manufacturing described in Patent Document 2 has highly hydrophobic particle surfaces, so the aqueous binder solution may not quickly penetrate into the powder layer. In such cases, the penetration takes time, which can reduce the supply rate of the aqueous binder solution or cause uneven penetration. This reduces the speed at which the object (modeled body) is manufactured and reduces the shape accuracy of the manufactured object.

[0008] Therefore, the challenge is to develop a powder that can efficiently produce layered objects with high shape accuracy by improving the packing ability of the powder layer and increasing the permeability of the binder solution into the powder layer. [Means for solving the problem]

[0009] The powder for additive manufacturing according to the application example of the present invention is A powder for additive manufacturing used in manufacturing an additive manufacturing body by binder jetting, Metal particles; a coating film provided on the surface of the metal particles and containing a compound derived from a silane coupling agent; Equipped with The silane coupling agent is composed of a structural unit represented by the following formula (1). [ka] [In formula (1), R are functional groups that are independent of each other, and 50% or more of the functional groups R contain an organic group that is any one of a carboxy group, a hydroxy group, an amino group, and an epoxy group. n is the number of repeating units and is 0 or more and 10 or less.]

[0010] The layered object according to the application example of the present invention is A powder for additive manufacturing according to an application example of the present invention; a binder that binds particles of the powder for additive manufacturing together; It has. [Brief explanation of the drawings]

[0011] [Figure 1] 1A to 1C are process diagrams illustrating a configuration of a method for manufacturing a layered object according to an embodiment. [Figure 2] 2A to 2C are diagrams for explaining a method for manufacturing the layered object shown in FIG. 1. [Figure 3] 2A to 2C are diagrams for explaining a method for manufacturing the layered object shown in FIG. 1. [Figure 4] 2A to 2C are diagrams for explaining a method for manufacturing the layered object shown in FIG. 1. [Figure 5] 2A to 2C are diagrams for explaining a method for manufacturing the layered object shown in FIG. 1. [Figure 6] 2A to 2C are diagrams for explaining a method for manufacturing the layered object shown in FIG. 1. [Figure 7] 2A to 2C are diagrams for explaining a method for manufacturing the layered object shown in FIG. 1. [Figure 8] 2A to 2C are diagrams for explaining a method for manufacturing the layered object shown in FIG. 1. [Figure 9] 2A to 2C are diagrams for explaining a method for manufacturing the layered object shown in FIG. 1. [Figure 10] 2A to 2C are diagrams for explaining a method for manufacturing the layered object shown in FIG. 1. [Figure 11] FIG. 1 is a cross-sectional view schematically illustrating a powder for additive manufacturing according to an embodiment. [Figure 12] 1 is an example of an infrared absorption spectrum obtained from a powder for additive manufacturing. [Figure 13] 1A to 1C are process diagrams illustrating a method for manufacturing a metal sintered body. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, preferred embodiments of the powder for layered manufacturing and layered manufactured body of the present invention will be described in detail with reference to the accompanying drawings.

[0013] 1. Manufacturing method for additive manufacturing objects First, a method for manufacturing a layered object according to an embodiment will be described.

[0014] FIG. 1 is a process diagram showing the configuration of a method for manufacturing an additive manufacturing object according to an embodiment. FIGS. 2 to 10 are diagrams for explaining the method for manufacturing the additive manufacturing object shown in FIG. 1. In FIGS. 2 to 10, three mutually orthogonal axes are defined: an X-axis, a Y-axis, and a Z-axis. Each axis is represented by an arrow, with the tip end side being the "plus side" and the base end side being the "minus side." In the following description, the plus side of the Z-axis will be referred to as "up" and the minus side of the Z-axis will be referred to as "down." Furthermore, both directions parallel to the X-axis will be referred to as X-axis directions, both directions parallel to the Y-axis will be referred to as Y-axis directions, and both directions parallel to the Z-axis will be referred to as Z-axis directions.

[0015] 1 to 10 is a method called the binder jet method, which includes a powder layer forming step S102, a binder solution supplying step S106, a repeating step S108, and a removal step S110, as shown in Fig. 1. The binder jet method has the advantage of being able to produce objects with complex shapes because it does not require a support structure to support the object.

[0016] In the powder layer forming step S102, the additive manufacturing powder 1 is spread to form a powder layer 31. In the binder solution supplying step S106, a binder solution 4 is supplied to a predetermined area of ​​the powder layer 31 to bond the particles in the powder layer 31 together, thereby obtaining a bonded layer 41. In the repeating step S108, the powder layer forming step S102 and the binder solution supplying step S106 are repeated one or more times to stack the bonded layers 41. This results in a layered object 6. In the removing step S110, the additive manufacturing object 6 is removed from the powder layer 31. Each step will be explained in turn below.

[0017] 1.1. Additive manufacturing equipment First, prior to describing the powder layer forming step S102, the layered manufacturing apparatus 2 will be described.

[0018] As shown in Figures 2 to 10, the additive manufacturing device 2 includes an apparatus main body 21 having a powder storage section 211 and a manufacturing section 212, a powder supply elevator 22 provided in the powder storage section 211, a manufacturing stage 23 provided in the manufacturing section 212, and a coater 24, a roller 25, and a liquid supply section 26 that are movably provided on the apparatus main body 21.

[0019] 2, the powder storage unit 211 is a recess that is provided in the device main body 21 and is open at the top. The powder storage unit 211 stores the additive manufacturing powder 1. An appropriate amount of the additive manufacturing powder 1 stored in the powder storage unit 211 is supplied to the manufacturing unit 212 by the coater 24.

[0020] A powder supply elevator 22 is disposed at the bottom of the powder storage unit 211. The powder supply elevator 22 is movable up and down with the additive manufacturing powder 1 loaded thereon. By moving the powder supply elevator 22 upward, the additive manufacturing powder 1 loaded on the powder supply elevator 22 is pushed up and overflows from the powder storage unit 211. This allows the overflowing additive manufacturing powder 1 to be moved toward the manufacturing unit 212.

[0021] The modeling unit 212 is provided in the device main body 21 and is a recessed portion that is open at the top. A modeling stage 23 is arranged inside the modeling unit 212. The powder 1 for additive manufacturing is spread in layers on the modeling stage 23 by a coater 24. The modeling stage 23 is also movable in the vertical direction while the powder 1 for additive manufacturing is spread on it. By appropriately setting the height of the modeling stage 23, the amount of powder 1 for additive manufacturing spread on the modeling stage 23 can be adjusted.

[0022] The coater 24 and roller 25 each extend in the Y-axis direction and are movable in the X-axis direction from the powder storage section 211 to the modeling section 212. The coater 24 drags the additive manufacturing powder 1, thereby leveling the additive manufacturing powder 1 and spreading it in layers. The roller 25 rolls the leveled additive manufacturing powder 1, thereby compressing the additive manufacturing powder 1 from above.

[0023] 5, the liquid supply unit 26 is configured by, for example, an inkjet head or a dispenser, and is movable in the X-axis and Y-axis directions in the modeling unit 212. The liquid supply unit 26 supplies a desired amount of binder solution 4 to a desired position. The liquid supply unit 26 may be equipped with multiple discharge nozzles. The binder solution 4 may be discharged from the multiple discharge nozzles simultaneously or with a time lag.

[0024] 1.2. Powder layer formation process In the powder layer forming step S102, the powder for additive manufacturing 1 is spread on the modeling stage 23 to form a powder layer 31. Specifically, as shown in FIGS. 2 and 3, a coater 24 is used to drag the powder for additive manufacturing 1 stored in the powder storage unit 211 onto the modeling stage 23 and smooth it to a uniform thickness. This results in the powder layer 31 shown in FIG. 4. At this time, the upper surface of the modeling stage 23 is lowered below the upper end of the modeling unit 212, and the thickness of the powder layer 31 can be adjusted by adjusting the amount of lowering.

[0025] The thickness of the powder layer 31 in this step is not particularly limited, but is preferably from 2 to 20 times, more preferably from 3 to 10 times, and even more preferably from 4 to 8 times the average particle size of the metal powder used in the additive manufacturing powder 1. If the thickness of the powder layer 31 is within this range, the shape precision of the finally obtained additive manufacturing body 6 can be sufficiently improved.

[0026] If the thickness of the powder layer 31 is below the lower limit, a larger number of powder layers 31 are required to manufacture the desired layered object 6. This may increase the time required to manufacture the layered object 6. On the other hand, if the thickness of the powder layer 31 exceeds the upper limit, the bonding layer 41 formed from the powder layer 31 also becomes thick, which may decrease the shape accuracy of the layered object 6.

[0027] Next, while compressing the powder layer 31 in the thickness direction with the roller 25, the roller 25 is moved in the X-axis direction as shown in FIG. 4. This increases the filling rate of the powder 1 for layered manufacturing in the powder layer 31. Note that compression with the roller 25 may be performed as needed and may be omitted. Alternatively, the powder layer 31 may be compressed by a means other than the roller 25, such as a pressure plate.

[0028] The relative density of the powder layer 31 after compression is preferably 40% or more, more preferably 45% to 70%, and even more preferably 50% to 65%. If the relative density is below the lower limit, the gaps between particles in the powder layer 31 become large, which may prevent the binder solution 4 from penetrating sufficiently. On the other hand, if the relative density is above the upper limit, the gaps between particles in the powder layer 31 may become too small. In this case, the continuity of the gaps may be lost, which may reduce the permeability of the binder solution 4.

[0029] The relative density of the powder layer 31 is the ratio of the density of the powder layer 31 to the true density of the material that constitutes the additive manufacturing powder 1. The density of the powder layer 31 can be calculated based on the volume calculated from the area and thickness of the powder layer 31 and the mass of the powder layer 31.

[0030] 1.3. Binder solution supply process 5, in the binder solution supplying step S106, droplets of the binder solution 4 are discharged from the liquid supply unit 26 onto a formation region 60 of the powder layer 31 that corresponds to the layered object 6 to be manufactured. In the formation region 60 to which the binder solution 4 is supplied, the particles of the powder 1 for layered object manufacturing are bound together, resulting in a bound layer 41 as shown in FIG.

[0031] The binder solution 4 is a liquid containing, for example, water and a binder component capable of binding the particles of the powder for layered manufacturing 1 together.

[0032] The surface tension of the binder solution 4 is preferably set to 20 mN / m or more and 40 mN / m or less, more preferably 20 mN / m or more and 35 mN / m or less, and even more preferably 20 mN / m or more and 30 mN / m or less. The driving force for permeation due to capillary action tends to increase as the surface tension of the binder solution 4 increases. Therefore, as long as the surface tension of the binder solution 4 is within the above range, the permeability of the binder solution 4 can be increased, even if the particle surfaces of the powder for additive manufacturing 1 are made hydrophobic, and the shape precision of the binder layer 41 can be improved.

[0033] If the surface tension of the binder solution 4 is below the lower limit, the driving force for permeation due to capillary action may not work sufficiently for the binder solution 4 supplied to the powder layer 31. As a result, the binder solution 4 may not permeate sufficiently into the powder layer 31, which may reduce the shape precision of the binder layer 41. On the other hand, if the surface tension of the binder solution 4 is above the upper limit, the surface tension becomes excessive, which may cause the droplets of the binder solution 4 to become spherical. In this case, the binder solution 4 may have difficulty permeating into the powder layer 31.

[0034] The surface tension of the binder solution 4 is measured using a surface tensiometer. Examples of the surface tensiometer include the CBVP-Z surface tensiometer manufactured by Kyowa Interface Science Co., Ltd.

[0035] Examples of binder components contained in the binder solution 4 include fatty acids, paraffin wax, microcrystalline wax, polyethylene, polypropylene, polystyrene, acrylic resins, polyamide resins, polyesters, stearic acid, polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), polyethylene glycol (PEG), urethane resins, epoxy resins, vinyl resins, unsaturated polyester resins, and phenolic resins. Adding these components to a solvent or dispersion medium containing water tends to reduce the surface tension of the binder solution 4. For this reason, the surface tension of the binder solution 4 can be adjusted depending on the type and amount of binder component added.

[0036] Among these, polyvinyl alcohol (PVA) or polyvinylpyrrolidone (PVP) is preferably used as the binder component. The binder solution 4 containing these binder components has a moderate affinity and viscosity for the additive manufacturing powder 1, and also has good binding properties. Therefore, the binder solution 4 containing these binder components contributes to the production of an additive manufacturing object 6 with particularly good shape accuracy.

[0037] The concentration of the binder component in the binder solution 4 is preferably 0.1% by mass or more and 20.0% by mass or less, more preferably 1.0% by mass or more and 15.0% by mass or less, and even more preferably 5.0% by mass or more and 12.0% by mass or less. This optimizes the viscosity of the binder solution 4 and ensures sufficient bonding strength between the particles of the powder for additive manufacturing 1. Furthermore, by setting the concentration of the binder component within the above range, the surface tension of the binder solution 4 can be optimized.

[0038] Furthermore, when the binder solution 4 contains a liquid other than water, examples of the liquid include alcohols, ketones, and carboxylic acid esters, and a mixture containing at least one of these is used. Adding these components to water tends to reduce the surface tension of the binder solution 4. This allows the surface tension of the binder solution 4 to be adjusted.

[0039] The water content in the binder solution 4 is not particularly limited, but is preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more. This allows the water content in the binder solution 4 to be sufficiently increased, thereby reducing the environmental impact when drying or disposing of the binder solution 4.

[0040] In addition to the above components, the binder solution 4 may contain additives such as viscosity adjusters, surfactants, moisturizing agents, stabilizers, antifoaming agents, crosslinking agents, and antioxidants.

[0041] The total content of the additives in the binder solution 4 is preferably 20.0% by mass or less, and more preferably 1.0% by mass or more and 15.0% by mass or less.

[0042] The movement speed of the liquid supply unit 26 is not particularly limited, but is preferably 0.1 mm / s to 20 mm / s, more preferably 1 mm / s to 15 mm / s, and even more preferably 3 mm / s to 10 mm / s. By setting the movement speed of the liquid supply unit 26 within this range, the ejection position accuracy of the droplets of the binder solution 4 can be improved. This improves the shape accuracy of the binder layer 41, and therefore the shape accuracy of the final layered object 6 obtained.

[0043] If the moving speed of the liquid supply unit 26 is lower than the lower limit, there is a risk of a decrease in the production efficiency of the layered object 6. On the other hand, if the moving speed of the liquid supply unit 26 is higher than the upper limit, there is a risk of a decrease in the shape accuracy of the bonding layer 41 because the accuracy of the droplet ejection position decreases.

[0044] The moving speed of the liquid supply unit 26 is the average speed of the liquid supply unit 26 measured at the timing when droplets of the binder solution 4 are discharged toward the formation region 60. The average speed is calculated by measuring the speed of the liquid supply unit 26 10 or more times at the timing when droplets are discharged and averaging the measured values.

[0045] The interval between droplets of the binder solution 4 is not particularly limited, but is preferably 1 μm to 90 μm, more preferably 5 μm to 80 μm, even more preferably 10 μm to 70 μm, and particularly preferably 20 μm to 60 μm. By setting the interval between droplets of the binder solution 4 within the above range, the binder solution 4 can be supplied uniformly and in a sufficient amount.

[0046] The interval between droplets of the binder solution 4 may be below the lower limit, but in that case, the improvement in the shape precision of the layered object 6 cannot be expected to be significant, and it may become difficult to increase the movement speed of the liquid supply unit 26, which may reduce the production efficiency of the layered object 6. On the other hand, if the interval between droplets of the binder solution 4 exceeds the upper limit, the droplets of the binder solution 4 that land on the powder layer 31 may be too far apart, preventing the formation of a continuous coating. In this case, there is a higher probability that particles will not bond together, and the shape precision of the layered object 6 will be reduced.

[0047] The ejection interval of the droplets of the binder solution 4 is determined by ejecting the binder solution 4 onto a smooth surface that does not absorb the binder solution 4 under the same conditions as when ejecting it onto the formation region 60, measuring the distance between the ejected droplets within a 5 mm x 5 mm area, and taking the average of these measurements. The distance between droplets is the distance between the centers of adjacent droplets. The average value is the average of the measurements obtained by measuring the distance between each of 10 or more pairs of randomly selected droplets.

[0048] Furthermore, the volume of the droplets of the binder solution 4 discharged from the liquid supply unit 26 is not particularly limited, but is preferably from 1 pL to 10 pL, more preferably from 1 pL to 8 pL, and even more preferably from 2 pL to 6 pL. Setting the volume of the droplets of the binder solution 4 within this range can improve the accuracy of the droplet discharge position, particularly at the outer edge of the binder layer 41. This can improve the shape accuracy of the layered object 6, particularly at the portion corresponding to the outer edge of the binder layer 41.

[0049] If the volume of the droplets of the binder solution 4 is below the lower limit, it becomes difficult to increase the movement speed of the liquid supply unit 26, which may reduce the production efficiency of the layered object 6. On the other hand, if the volume of the droplets of the binder solution 4 exceeds the upper limit, the mass of the droplets may increase. In this case, the impact when the droplets land on the powder layer 31 increases, reducing the shape accuracy of the binder layer 41, which in turn reduces the shape accuracy of the layered object 6.

[0050] The volume of the droplets of the binder solution 4 is determined by observing the plan view and cross section of the droplets after discharging the binder solution 4 onto a smooth surface that does not absorb the binder solution 4 under the same conditions as when discharging it onto the formation region 60. The average value is determined by averaging the volumes of 10 or more droplets randomly selected.

[0051] Simultaneously with or after the supply of the binder solution 4, the powder layer 31 to which the binder solution 4 has been supplied may be subjected to a drying process. Examples of drying processes include heating and gas spraying. The drying process can promote the drying of the powder layer 31 to which the binder solution 4 has been supplied. This allows the penetration range of the binder solution 4 to be controlled as desired, further improving the shape precision of the layered object 6 that is finally obtained.

[0052] The heating temperature when heating is not particularly limited, but is preferably 50°C or higher and 250°C or lower, and more preferably 70°C or higher and 200°C or lower.

[0053] Furthermore, if the binder has photo-curing or ultraviolet-curing properties, a light irradiation process or ultraviolet-irradiation process may be performed, which allows the binder to be solidified or hardened in a shorter time.

[0054] 1.4.Repetitive process In the repeating step S108, the powder layer forming step S102 and the binder solution supplying step S106 are repeated one or more times. In other words, these steps are performed two or more times in total. This results in multiple bonding layers 41 being stacked. By stacking the bonding layers 41 in this manner, a layered object 6 having a desired three-dimensional shape is obtained, as shown in FIG. 10.

[0055] Specifically, first, a new powder layer 31 shown in Fig. 7 is formed on the binder layer 41 shown in Fig. 6. Next, as shown in Fig. 8, a binder solution 4 is supplied to a formation region 60 of the newly formed powder layer 31. This results in a second binder layer 41 shown in Fig. 9. The two binder layers 41 may have the same shape or different shapes.

[0056] 1.5.Removal process In the removal step S110, the binder layer 41 is removed from the powder layer 31. In this way, the layered object 6 is obtained.

[0057] Of the powder layer 31, the powder for layered manufacturing 1 that did not form the binder layer 41 is collected and reused as necessary, that is, it is used again to manufacture the layered object 6.

[0058] 2. Powder for additive manufacturing Next, the powder for additive manufacturing according to the embodiment will be described. FIG. 11 is a cross-sectional view that schematically shows the powder for layered manufacturing 1 according to the embodiment.

[0059] The powder for layered manufacturing 1 according to this embodiment is a powder used to manufacture a layered manufactured body 6 by, for example, the binder jet method described above.

[0060] The powder for additive manufacturing 1 shown in Fig. 11 has a plurality of surface-coated particles 13, each of which includes a metal particle 11 made of a metal material and a coating 12 covering the surface of the metal particle 11. The coating 12 contains a compound derived from a silane coupling agent. Note that the coating 12 preferably covers the entire surface of the metal particle 11, but some portions may not be covered.

[0061] 2.1. Metal particles The metal material comprising the metal particles 11 is not particularly limited and may be any metal material that has sinterability. Examples include simple substances such as Fe, Ni, Co, and Ti, as well as alloys and intermetallic compounds containing these as main components.

[0062] The preferred metallic material is an Fe-based metallic material. Fe-based metallic materials are metallic materials with an Fe atomic ratio of over 50%. Fe-based metallic materials are easy to obtain and can be used to produce sintered metal bodies with excellent mechanical properties.

[0063] Examples of Fe-based metallic materials include stainless steels such as austenitic stainless steel, ferritic stainless steel, martensitic stainless steel, precipitation hardened stainless steel, and austenitic-ferritic (duplex) stainless steel, as well as low-carbon steel, carbon steel, heat-resistant steel, die steel, high-speed tool steel, Fe-Ni alloys, and Fe-Ni-Co alloys.

[0064] Among these, stainless steel is preferably used as the Fe-based metallic material. Stainless steel is a type of steel that has excellent mechanical strength and corrosion resistance. Therefore, by using powder 1 for additive manufacturing made of stainless steel, it is possible to efficiently manufacture a metal sintered body that has excellent mechanical strength and corrosion resistance and high shape accuracy.

[0065] Examples of austenitic stainless steel include SUS301, SUS301L, SUS301J1, SUS302B, SUS303, SUS304, SUS304Cu, SUS304L, SUS304N1, SUS304N2, SUS304LN, SUS304J1, SUS304J2, SUS305, SUS309S, SUS310S, SUS312L, SUS315J1, SUS315J2, SUS316, SUS316L, SUS316N, SUS316LN, SUS316Ti, SUS316J1, SUS316J1L, SUS317, SUS317L, SUS317LN, SUS317J1, SUS317J2, SUS836L, SUS890L, SUS321, SUS347, SUSXM7, and SUSXM15J1.

[0066] Examples of ferritic stainless steel include SUS405, SUS410L, SUS429, SUS430, SUS430LX, SUS430J1L, SUS434, SUS436L, SUS436J1L, SUS445J1, SUS445J2, SUS444, SUS447J1, and SUSXM27.

[0067] Examples of martensitic stainless steel include SUS403, SUS410, SUS410S, SUS420J1, SUS420J2, and SUS440A.

[0068] Precipitation hardening stainless steel includes, for example, SUS630 and SUS631.

[0069] Examples of austenitic-ferritic (duplex) stainless steel include SUS329J1, SUS329J3L, and SUS329J4L.

[0070] The above symbols are material symbols based on the JIS standard. The types of stainless steel in this specification are distinguished by the above material symbols.

[0071] The additive manufacturing body 6 may be manufactured using two or more types of additive manufacturing powder 1 made of different metal materials. For example, the additive manufacturing body 6 may be divided into two parts, one part made using additive manufacturing powder 1 made of a first metal material, and the other part made using additive manufacturing powder 1 made of a second metal material.

[0072] 2.2.Coating The coating 12 contains a compound derived from a silane coupling agent. By providing such a coating 12, it is possible to obtain a powder for additive manufacturing 1 that maintains high fluidity and high packing ability when forming the powder layer 31. Furthermore, by providing the coating 12, it is possible to increase the affinity between the powder for additive manufacturing 1 and the binder.

[0073] The silane coupling agent is a compound composed of a structural unit represented by the following formula (1).

[0074] [ka] [In formula (1), R are functional groups that are independent of each other, and 50% or more of the functional groups R contain an organic group that is any one of a carboxy group, a hydroxy group, an amino group, and an epoxy group. n is the number of repeating units and is 0 or more and 10 or less.]

[0075] All of the above organic groups are hydrophilic. Therefore, when more than half of the functional groups R of the structural units contain this hydrophilic organic group, the particle surfaces of the powder for additive manufacturing 1 become moderately hydrophilic. Therefore, when the binder solution 4 is supplied in the binder solution supplying step S106, the permeability of the binder solution 4 into the powder layer 31 can be improved. As a result, an additive manufacturing body 6 with high shape accuracy is finally obtained. Note that the above compounds may be crosslinked to form a polymer. This further improves the adhesion of the coating 12 to the metal particles 11.

[0076] Furthermore, all of the organic groups can act as hydrogen-bonding interactive groups, which allows the silane coupling agent to bond well to the surfaces of the metal particles 11. This allows for stabilization of the coating 12 that coats the surfaces of the metal particles 11.

[0077] Furthermore, in the structural units, the ratio of the number of functional groups R containing the organic group to all functional groups R is preferably 50% or more and 100% or less, and more preferably 60% or more and 100% or less. This further optimizes the balance between hydrophilicity and hydrophobicity on the particle surfaces of the powder for additive manufacturing 1. This results in a powder for additive manufacturing 1 that can form a powder layer 31 that has excellent moisture resistance and excellent permeability for the binder solution 4.

[0078] If the ratio of the number of functional groups R containing the organic group is below the lower limit, the hydrophilicity of the particle surfaces of the powder 1 for additive manufacturing may decrease, resulting in a decrease in the permeability of the binder solution 4. On the other hand, if the ratio of the number of functional groups R containing the organic group is above the upper limit, the adhesion between the metal particles 11 and the coating 12 in the particles of the powder 1 for additive manufacturing may decrease.

[0079] The functional group R refers to all atomic groups bonded to Si atoms, excluding oxygen atoms sandwiched between Si atoms.

[0080] The functional group R may contain a monovalent group other than the above organic groups. Such a monovalent group may be, for example, a hydrophobic organic group such as an alkyl group having from 1 to 6 carbon atoms or an aryl group. When the functional group R contains a hydrophobic organic group, an additive manufacturing powder 1 having both hydrophilic and hydrophobic properties can be obtained. Such additive manufacturing powder 1 has good fluidity and filling properties, even in a high-temperature and high-humidity environment, and can form a powder layer 31 that has excellent permeability for the binder solution 4.

[0081] Furthermore, when the functional group R contains the organic group, the organic group may be located at the terminal of the functional group R, and any divalent group may be contained between the organic group and the Si atom. Examples of the divalent group include -NH-CO-, -NH-, -O-, -S-, -CO-, and -O-CO-.

[0082] Preferably, at least one of the functional groups R contains a hydroxy group, which easily undergoes dehydration condensation with the hydroxy groups present on the surface of the metal particles, thereby further improving the adhesion of the coating.

[0083] In the structural units, the ratio of the number of functional groups R containing hydroxy groups is preferably 10% or more, more preferably 20% to 95%, and even more preferably 30% to 90%. This makes it possible to particularly optimize the balance between hydrophilicity and hydrophobicity on the particle surfaces of the powder for layered manufacturing 1.

[0084] Furthermore, it is preferable that at least one of the functional groups R contains a carboxy group. In particular, it is preferable that the functional groups R located at both ends of the siloxane bond each contain a carboxy group. This carboxy group easily reacts with adjacent structural units to form a gel. This allows for the production of a silane coupling agent with excellent film-forming properties.

[0085] In the structural units, the ratio of the number of functional groups R containing carboxy groups is preferably 10% to 40%, more preferably 15% to 35%, thereby obtaining a coating 12 that has excellent film-forming properties and excellent adhesion to the surfaces of metal particles 11.

[0086] Furthermore, the ratio of the number of alkoxy groups among the functional groups R of the structural units is preferably 10% or less, and more preferably 5% or less. This reduces the amount of alcohol generated when the alkoxy groups bond to the particle surfaces of the powder for additive manufacturing 1. As a result, it is possible to reduce the environmental impact and prevent the deterioration of the coating quality due to alcohol.

[0087] The number of repeating units n is set to 0 or more and 10 or less as described above, but is preferably set to 0 or more and 5 or less, and more preferably set to 0 or more and 2 or less. This allows the coating 12 to be formed evenly on the surface of the metal particles 11. As a result, the powder for additive manufacturing 1 can be obtained that has good flowability and filling properties and is capable of forming a powder layer 31 that is excellent in permeability for the binder solution 4.

[0088] The average thickness of the coating 12 is not particularly limited, but is preferably 100 nm or less, more preferably 0.5 nm to 50 nm, and even more preferably 1 nm to 10 nm, which ensures a film thickness necessary to maintain the coating 12.

[0089] The average thickness of the coating 12 can be determined by, for example, qualitative and quantitative analysis in the depth direction using a combination of X-ray photoelectron spectroscopy and ion sputtering. Specifically, the concentration of the component derived from the silane coupling agent is examined along the depth direction. The region where the concentration of the component derived from the silane coupling agent is relatively high is then determined as the average thickness of the coating 12. Specifically, when the concentration changes near the boundary between the coating 12 and the metal particles 11, half of the concentration change, that is, the position corresponding to the midpoint between the concentration on the coating 12 side and the concentration on the metal particles 11 side, is considered to be the boundary, and the thickness on the surface side of the boundary can be determined as the average thickness of the coating 12.

[0090] Furthermore, the coating 12 may be a multilayer film in which molecules of the aforementioned compound are stacked in multiple layers, for example, two to ten layers. However, it is preferably a monomolecular film of the aforementioned compound. The coating 12, which is a monomolecular film, can minimize its thickness. As a result, when an additive manufacturing product 6 is produced, an additive manufacturing product 6 having a low occupancy rate of the coating 12 and a high occupancy rate of the metal particles 11 can be obtained. When such an additive manufacturing product 6 is subjected to a sintering process, for example, the shrinkage rate can be reduced, which is useful in that a metal sintered body with high shape precision can be obtained.

[0091] The monolayer can be formed by utilizing the self-organization of a silane coupling agent. The coupling agent is densely arranged on the surface of the metal particles 11, so that the monolayer can be formed efficiently.

[0092] Whether or not the coating 12 is a monolayer can be determined, for example, if the average thickness of the coating 12 measured by the above-mentioned method is equal to or less than the molecular size of the silane coupling agent, then the coating 12 can be evaluated as a monolayer.

[0093] The coating 12 may contain any component other than the above-mentioned compound. In this case, in order to reliably obtain the above-mentioned effects, the mass ratio of the above-mentioned compound is preferably greater than 50%, more preferably 70% or more, and even more preferably 90% or more.

[0094] 2.3. Various properties of powders for additive manufacturing Next, various properties of the powder for layered manufacturing 1 will be described.

[0095] 2.3.1. Infrared spectroscopy The powder for additive manufacturing 1 according to this embodiment can be subjected to infrared spectroscopic analysis to evaluate the permeability of the aqueous binder solution 4. Specifically, first, the powder for additive manufacturing 1 is subjected to infrared spectroscopic analysis to obtain an infrared absorption spectrum. A Fourier transform infrared spectrometer is used for the infrared spectroscopic analysis. In particular, the ATR method is preferably used. Next, the areas of the waveform P1 derived from Si-O bonds (siloxane bonds) and the waveform P2 derived from C-H bonds in the infrared absorption spectrum are obtained.

[0096] The top of waveform P1 is at a wave number of 1120 cm -1 More than 1140cm -1 The top of waveform P2 is located at wavenumber 2700 cm -1 More than 3000cm -1 Located below.

[0097] In the powder for layered manufacturing 1 according to this embodiment, the infrared absorption spectrum obtained has a waveform P1 and a waveform P2. The ratio P2 / P1 of the area of ​​waveform P2 to the area of ​​waveform P1 is 0.5 or less, preferably 0.001 or more and 0.4 or less, and more preferably 0.01 or more and 0.2 or less.

[0098] If the ratio P2 / P1 is within the above range, the hydrophobicity resulting from C-H bonds is suppressed on the particle surfaces of the additive manufacturing powder 1. This results in an additive manufacturing powder 1 with appropriate hydrophilicity. As a result, an additive manufacturing powder 1 is obtained that can form a powder layer 31 that has excellent permeability to the binder solution 4. In addition, a decrease in the moisture resistance of the additive manufacturing powder 1 is suppressed, ensuring flowability and fillability.

[0099] The ratio P2 / P1 may be below the lower limit, but in that case, the moisture resistance of the powder 1 for layered manufacturing may decrease, and the fluidity and filling ability may decrease. On the other hand, if the ratio P2 / P1 exceeds the upper limit, the permeability of the binder solution 4 in the powder layer 31 may decrease.

[0100] In some cases, waveforms P1 and P2 overlap with waveforms derived from other bonds. In such cases, waveform separation can be performed in a program that analyzes the infrared absorption spectrum, and the areas of the separated waveforms can be used as the areas of waveforms P1 and P2.

[0101] Fig. 12 is an example of an infrared absorption spectrum SP obtained from the powder for layered manufacturing 1. The horizontal axis of Fig. 12 represents wave numbers (cm -1 ) and the vertical axis is absorbance.

[0102] The infrared absorption spectrum SP shown in Figure 12 has waveforms P1 and P2. Meanwhile, waveform P2 overlaps with waveform P3, which is derived from an OH bond. In such a case, waveforms P2 and P3 can be separated using a waveform separation program (curve fitting program).

[0103] 2.3.2. Coverage The ratio of the area of ​​the entire surface of the metal particle 11 that is covered by the coating 12 is referred to as the "coverage." In the powder for additive manufacturing 1 according to this embodiment, the coverage of the coating 12 is preferably 10% or more and 150% or less, more preferably 20% or more and 120% or less, and even more preferably 30% or more and 100% or less. This makes it possible to impart hydrophilicity to the surfaces of the metal particles 11 evenly. This allows for the production of a powder for additive manufacturing 1 that can form a powder layer 31 that has particularly good permeability for the binder solution 4.

[0104] The coverage of the coating 12 can be calculated from the amount of the coating 12, the amount of the metal particles 11, the minimum coverage area of ​​the coupling agent, and the specific surface area of ​​the metal particles 11. The amount of the coating 12 can be calculated based on the concentration of the constituent elements of the silane coupling agent by, for example, performing qualitative and quantitative analysis of the powder for additive manufacturing 1 using X-ray photoelectron spectroscopy. For example, if the coupling agent is a silane coupling agent, the amount of the compound constituting the coating 12 can be calculated based on the Si concentration. The minimum coverage area of ​​the coupling agent is available from the manufacturer of each type of coupling agent. The specific surface area of ​​the metal particles 11 is measured using a specific surface area measuring device after removing the coating 12 from the powder for additive manufacturing 1 using, for example, a chemical. An example of a specific surface area measuring device is the BET specific surface area measuring device HM1201-010 manufactured by Mountech Co., Ltd.

[0105] 2.3.3.Particle size distribution When the particle size distribution of the metal particles 11 is obtained on a volume basis using a laser diffraction particle size distribution analyzer, the particle size D50 is the particle size at which the cumulative frequency is 50% from the smallest diameter side. An example of an apparatus for measuring particle size distribution is Microtrac HRA9320-X100 manufactured by Nikkiso Co., Ltd.

[0106] The particle size D50 (average particle size) of the metal particles 11 is preferably 1.0 μm or more and 15.0 μm or less, more preferably 3.0 μm or more and 12.0 μm or less, and even more preferably 4.0 μm or more and 10.0 μm or less. This results in a powder for additive manufacturing 1 that can produce an additive manufacturing body 6 with excellent sinterability. Furthermore, the powder for additive manufacturing 1 that can form a powder layer 31 with excellent fluidity and high packing density is obtained.

[0107] If the particle size D50 is below the lower limit, the particles of the additive manufacturing powder 1 may be more likely to agglomerate. If agglomeration occurs, the fluidity of the additive manufacturing powder 1 may decrease, and the density of the metal sintered body may decrease. On the other hand, if the particle size D50 is above the upper limit, the sinterability of the additive manufacturing powder 1 may decrease, and when a metal sintered body is obtained from the additive manufacturing body 6, the density of the metal sintered body may decrease.

[0108] 2.3.4. Water contact angle The silane coupling agent used in this embodiment is configured so that when the contact angle of water is measured by the following method, the measured value falls within a predetermined range.

[0109] First, a silane coupling agent is diluted with pure water to prepare a 0.3% by mass solution. The resulting solution is then applied to a glass substrate to obtain a coating film. The glass substrate with the coating film formed thereon is then placed in a thermostatic chamber and heated to 100°C for 1 hour to dry. This results in a dried film on the glass substrate. The water contact angle of the resulting dried film is then measured using a contact angle measuring device. The contact angle measuring device used is a DropMaster 500 contact angle measuring device manufactured by Kyowa Interface Science Co., Ltd. The θ / 2 method is used for the measurement, and measurements are taken 5 seconds after the droplets land. The measurement conditions are an air temperature of 25°C, a relative humidity of 50%±5%, and a water droplet volume of 3 μL.

[0110] When the water contact angle of the obtained dried film is measured by the above method, the measured value is preferably 30° to 90°, more preferably 40° to 80°, and even more preferably 50° to 70°. By using a silane coupling agent configured so that the water contact angle is within the above range, it is possible to obtain a powder for additive manufacturing 1 that has good fluidity and filling properties, even in a high-temperature, high-humidity environment, and is capable of forming a powder layer 31 that has excellent permeability for the binder solution 4.

[0111] If the water contact angle is below the lower limit, the moisture resistance of the powder 1 for use in additive manufacturing may decrease, resulting in decreased fluidity and filling ability. On the other hand, if the water contact angle is above the upper limit, the hydrophilicity of the powder 1 for use in additive manufacturing may decrease, resulting in decreased permeability of the binder solution 4 in the powder layer 31.

[0112] The contact angle of water is affected by the functional group R of the silane coupling agent. Therefore, when the functional group R contains a large amount of the aforementioned hydrophilic organic groups, the contact angle of water tends to be small. On the other hand, when the functional group R contains a large amount of the aforementioned hydrophobic organic groups, the contact angle of water tends to be large.

[0113] 2.3.5. Bulk and tapped density The bulk density AD of the powder for additive manufacturing 1 according to this embodiment is 2.50 g / cm 3 More than 3.70g / cm 3 Preferably, it is 2.70 g / cm or less. 3 More than 3.60g / cm 3 More preferably, it is 3.00 g / cm or less. 3 More than 3.50g / cm 3 It is even more preferable that the bulk density AD is equal to or less than this range. If the bulk density AD is within this range, good packing properties can be ensured even in the natural state. This allows the powder layer 31 to be formed with a high packing rate when the powder for additive manufacturing 1 is used to form the powder layer 31. As a result, a dense additive manufacturing body 6 with high shape accuracy can be obtained, and this can be used to finally manufacture a metal sintered body with high density and high shape accuracy.

[0114] The bulk density AD of the powder for additive manufacturing 1 is measured in accordance with the method for measuring the apparent density of metal powders specified in JIS Z 2504:2012. A powder property evaluation device, Powder Tester (registered trademark) PT-X, manufactured by Hosokawa Micron Corporation, is preferably used to measure the bulk density AD. Prior to measuring the bulk density AD, the powder for additive manufacturing 1 to be measured is preferably left in an environment at a temperature of 25°C and a relative humidity of 50% for at least one hour.

[0115] The tap density of additive manufacturing powder 1 is 4.10 g / cm 3 More than 4.80g / cm 3 Preferably, it is 4.20 g / cm or less. 3 More than 4.70g / cm 3 More preferably, it is 4.30 g / cm or less. 3 More than 4.60g / cm 3 If the tap density TD is within the above range, a high filling rate can be obtained when the powder layer 31 is leveled by the building stage 23 or compressed by the roller 25. This makes it possible to obtain a dense layered manufactured body 6 with high shape accuracy, which can then be used to finally manufacture a metal sintered body with high density and high shape accuracy.

[0116] The tap density TD of the powder for additive manufacturing 1 is measured using a powder property evaluation device, Powder Tester (registered trademark) PT-X, manufactured by Hosokawa Micron Corp. Before measuring the tap density TD, the powder for additive manufacturing 1 to be measured is preferably left to stand in an environment at a temperature of 25°C and a relative humidity of 50% for at least one hour.

[0117] Furthermore, the ratio of the tap density TD to the bulk density AD of the additive manufacturing powder 1 is preferably 1.15 or more and 1.50 or less, more preferably 1.20 or more and 1.45 or less, and even more preferably 1.25 or more and 1.36 or less. If this ratio is within the above range, the difference in packing rate between the additive manufacturing powder 1 in its natural state and the additive manufacturing powder 1 after vibration, load, or the like has been applied can be reduced. Therefore, differences in packing rate are unlikely to occur in the powder layer 31, and deformation of the additive manufacturing body 6 due to differences in packing rate, etc. can be suppressed.

[0118] Although this ratio may be below the lower limit, it may be more difficult to produce the powder for additive manufacturing 1 having such properties. On the other hand, if this ratio exceeds the upper limit, the difference in filling rate becomes large, which may result in deformation of the additive manufacturing body 6.

[0119] 3. Manufacturing method of powder for additive manufacturing Next, a method for producing the powder 1 for layered manufacturing will be described.

[0120] The powder for additive manufacturing 1 is produced through, for example, a preparation step, a coupling agent reaction step, and a coating formation step.

[0121] 3.1. Preparation process In the preparation step, metal particles 11 are prepared. The metal particles 11 may be produced by any method, but are preferably produced by an atomization method such as water atomization, gas atomization, or rotary water atomization, and are more preferably produced by water atomization or rotary water atomization. The surfaces of metal particles 11 produced by these methods are likely to be covered with hydroxyl groups derived from water. This improves the adhesion of the coating 12, and even if the coating 12 is thin, the fluidity of the additive manufacturing powder 1 can be sufficiently improved. As a result, an additive manufacturing body 6 can be produced in which the occupancy of the metal particles 11 is higher than that of the coating 12, and which has a small shrinkage rate during sintering.

[0122] If necessary, the surfaces of the metal particles 11 may be subjected to a known pretreatment for generating hydroxyl groups.

[0123] 3.2. Coupling agent reaction step In the coupling agent reaction step, the silane coupling agent is reacted with the metal particles 11. Examples of this procedure include a procedure in which both the metal particles 11 and the silane coupling agent are placed in a chamber and then the chamber is heated (Method 1), a procedure in which the metal particles 11 are placed in a chamber and then the silane coupling agent is sprayed into the chamber while stirring the metal particles 11 (Method 2), and a procedure in which water, a coupling agent, and an alkaline solution such as ammonia or sodium hydroxide are added to a primary alcohol such as methanol, ethanol, or isopropyl alcohol, stirred, filtered, and then dried (Method 3). The silane coupling agent is supplied by leaving it stationary in the chamber or spraying it into the chamber.

[0124] The amount of silane coupling agent added is not particularly limited, but is preferably 0.01% by mass or more and 1.00% by mass or less, and more preferably 0.05% by mass or more and 0.50% by mass or less, relative to the metal particles 11. This allows the metal particles 11 to be evenly coated with the coating 12. As a result, the obtained powder for additive manufacturing 1 has good fluidity and filling properties, even in a high-temperature and high-humidity environment, and is capable of forming a powder layer 31 that has excellent permeability for the binder solution 4.

[0125] 3.3. Film formation process In the coating formation step, the metal particles 11 to which the silane coupling agent is attached are heated. As a result, a coating 12 is formed on the surface of the metal particles 11, and the powder for additive manufacturing 1 is obtained. In addition, the heating can remove any unreacted silane coupling agent.

[0126] The heating temperature of the metal particles 11 to which the silane coupling agent is attached is not particularly limited, but is preferably 50°C or higher and 300°C or lower, more preferably 100°C or higher and 250°C or lower, and even more preferably 120°C or higher and 200°C or lower. The heating time is preferably 10 minutes or higher and 24 hours or lower, more preferably 30 minutes or higher and 10 hours or lower, and even more preferably 1 hour or higher and 6 hours or lower. Note that this heating time refers to the duration of the heating temperature. Examples of the atmosphere for the heat treatment include air and inert gas atmospheres.

[0127] In addition, it is preferable to perform at least one of the coupling agent reaction process and the coating formation process in a sealed container, and more preferably to perform both processes in a sealed container. This prevents the silane coupling agent from decomposing and volatilizing. As a result, the reaction amount and deposition density of the silane coupling agent can be suitably controlled, and ultimately, a coating 12 having the desired properties can be formed.

[0128] 4.Method for manufacturing sintered metal bodies By subjecting the layered manufactured body 6 to a sintering process, a metal sintered body is obtained. FIG. 13 is a process diagram for explaining the method for manufacturing a metal sintered body.

[0129] The method for manufacturing a metal sintered body shown in Figure 13 includes a manufacturing process S202 in which an additive manufacturing body 6 is obtained by the above-mentioned method for manufacturing an additive manufacturing body, and a sintering process S204 in which the additive manufacturing body 6 is sintered to obtain a metal sintered body.

[0130] 4.1. Molding process In the modeling step S202, the layered object 6 is obtained by the above-described method for manufacturing a layered object.

[0131] 4.2.Sintering process In the sintering step S204, the layered manufactured body 6 is sintered to obtain a metal sintered body.

[0132] When the sintering process performed under the above conditions is referred to as "main sintering," the layered product 6 may be subjected to at least one of "pre-sintering" and "debinding," which correspond to pre-treatments prior to the main sintering, as needed. This makes it possible to remove at least a portion of the binder contained in the layered product 6 and sinter a portion of the layered product 6. This makes it possible to suppress unintended deformation during the main sintering.

[0133] The metal sintered body obtained as described above can be used as a material for constituting all or part of transportation equipment parts such as automobile parts, bicycle parts, railway vehicle parts, ship parts, aircraft parts, and space transport vehicle parts; electronic equipment parts such as personal computer parts, mobile phone terminal parts, tablet terminal parts, and wearable terminal parts; electrical equipment parts such as refrigerators, washing machines, and air conditioners; machine parts such as machine tools and semiconductor manufacturing equipment; plant parts such as nuclear power plants, thermal power plants, hydroelectric power plants, refineries, and chemical complexes; watch parts; and decorative items such as metal tableware, jewelry, and eyeglass frames.

[0134] 5. Effects of the above embodiment As described above, the powder for additive manufacturing 1 according to the embodiment is a powder for additive manufacturing used to manufacture an additive manufacturing body 6 by the binder jet method, and includes metal particles 11 and coatings 12 that are provided on the surfaces of the metal particles 11 and contain a compound derived from a silane coupling agent. The silane coupling agent is composed of a structural unit represented by the following formula (1):

[0135] [ka] [In formula (1), R are functional groups that are independent of each other, and 50% or more of the functional groups R contain an organic group that is any one of a carboxy group, a hydroxy group, an amino group, and an epoxy group. n is the number of repeating units and is 0 or more and 10 or less.]

[0136] With this configuration, it is possible to form a powder layer 31 that has good filling properties and high permeability for the binder solution 4, and to realize a powder for additive manufacturing 1 that can efficiently produce an additive manufacturing body 6 with high shape accuracy.

[0137] In addition, in the powder for layered manufacturing 1 according to the embodiment, the number of repeating units n is 0 or more and 5 or less.

[0138] With this configuration, the coating 12 can be formed evenly on the surfaces of the metal particles 11. As a result, the powder 1 for additive manufacturing can be obtained, which has good flowability and filling properties and can form a powder layer 31 that is excellent in permeability for the binder solution 4.

[0139] Furthermore, when the powder for additive manufacturing 1 according to the embodiment is subjected to infrared spectroscopic analysis, the obtained infrared absorption spectrum has waveforms P1 and P2. -1 More than 1140cm -1 The waveform P2 is derived from the Si-O bond located at the wavenumber 2700 cm. -1 More than 3000cm -1 The waveform is derived from a C-H bond located below. The ratio P2 / P1 of the area of ​​waveform P2 to the area of ​​waveform P1 is 0.5 or less.

[0140] This configuration makes it possible to obtain a powder for additive manufacturing 1 that has appropriate hydrophilicity. As a result, it is possible to obtain a powder for additive manufacturing 1 that can form a powder layer 31 that has excellent permeability for the binder solution 4. In addition, it is possible to prevent the moisture resistance of the powder for additive manufacturing 1 from decreasing, and ensure fluidity and filling properties.

[0141] Furthermore, in the powder for additive manufacturing 1 according to the embodiment, the silane coupling agent is diluted to a concentration of 0.3% by mass and applied to a glass substrate. The resulting coating film is then heated at 100°C for 1 hour to dry it, and when the water contact angle of the resulting dried film is measured using a contact angle meter, the measured value is between 30° and 90°.

[0142] According to this configuration, the powder for additive manufacturing 1 can be obtained that has good fluidity and filling properties even in a high-temperature and high-humidity environment, and can form a powder layer 31 that has excellent permeability for the binder solution 4.

[0143] In addition, in the powder for layered manufacturing 1 according to the embodiment, the average particle size of the metal particles 11 is 1.0 μm or more and 15.0 μm or less.

[0144] According to this configuration, the powder for additive manufacturing 1 can be obtained, which can produce an additive manufacturing body 6 with excellent sinterability. Also, the powder for additive manufacturing 1 can be obtained, which has excellent fluidity and can form a powder layer 31 with a high packing density.

[0145] Moreover, the layered manufacturing body 6 according to the embodiment includes the powder for layered manufacturing 1 according to the embodiment, and a binder that binds the particles of the powder for layered manufacturing 1 together. With this configuration, a layered object 6 with a high degree of shape volume can be obtained.

[0146] The powder for additive manufacturing and the additive manufacturing body of the present invention have been described above based on the illustrated embodiment, but the present invention is not limited to this, and for example, any desired process may be added to the above embodiment. [Example]

[0147] Next, specific examples of the present invention will be described. 6. Preparation of powder for additive manufacturing First, metal particles were produced using the water atomization method. Precipitation hardening stainless steel SUS630 (17-4PH) was used as the raw material. Next, a coating was formed on the obtained metal powder using a silane coupling agent. The reaction of the silane coupling agent and the subsequent heat treatment were both carried out with the metal powder and silane coupling agent in a sealed container. This resulted in the production of powder for additive manufacturing.

[0148] Next, the average particle size of the produced metal particles, the compound of the silane coupling agent, the ratio of hydrophilic organic groups in the functional groups of the silane coupling agent, the ratio of hydroxyl groups, the ratio of carboxyl groups, the area ratio P2 / P1 in the infrared absorption spectrum, the coating coverage, the water contact angle, the bulk density, and the tap density were measured. The measurement results are shown in Table 1.

[0149] The compounds shown in Table 1 are as follows: Compound A-1: ​​A compound composed of a structural unit represented by the following formula (2), in which the functional group R contains a carboxy group and a hydroxy group

[0150] [ka]

[0151] Compound A-2: A compound composed of a structural unit represented by the following formula (3), in which the functional group R contains a primary amino group and a hydroxy group

[0152] [ka]

[0153] Compound A-3: A compound composed of a structural unit represented by the following formula (4), in which the functional group R contains an alkylene glycol group and a hydroxy group The alkylene glycol group is a group having a structure in which one or more "-CH2CH2O-" units are repeated. In Compound A-3, the terminal bonded to the oxygen atom is a methyl group.

[0154] [ka]

[0155] Compound B-1: 3-aminopropyltrimethoxysilane represented by the following formula (5):

[0156] [ka]

[0157] Compound C-1: Phenyltrimethoxysilane represented by the following formula (6)

[0158] [ka]

[0159] In Table 1, powders for additive manufacturing that correspond to the present invention are designated as "Examples," and powders for additive manufacturing that do not correspond to the present invention are designated as "Comparative Examples."

[0160] 6. Evaluation of Powders for Additive Manufacturing The powder for additive manufacturing of each sample number was evaluated as follows.

[0161] 6.1.Fillability 50 g of each sample No. of additive manufacturing powder was subjected to a heat treatment in an air atmosphere at 200°C for 24 hours. The heat-treated additive manufacturing powder was then placed in a 50 mL screw cap vial. The screw cap vial was then held upright and the height from the bottom to the top of the powder was measured. The measured height was then compared with the following evaluation criteria to relatively evaluate the packing ability of the additive manufacturing powder. The evaluation results are shown in Table 1.

[0162] A: Height is 25mm or less (especially high filling ability) B: Height is over 25mm and 30mm or less (slightly high filling ability) C: Height is over 30 mm (poor filling ability)

[0163] 6.2.Water permeability Each sample number of additive manufacturing powder was placed in a container and compressed to a relative density of 51%, forming a powder layer measuring 10 mm or more x 10 mm or more and 10 mm thick. The relative density of the powder layer was calculated from the volume determined from the area and thickness of the powder layer and the mass of the powder layer. Next, 40 μL of pure water was supplied as droplets to the powder layer. The time elapsed from the time of supply until all of the supplied water had permeated the powder layer was measured as the water penetration time. The obtained water penetration time was evaluated for water permeability according to the following evaluation criteria.

[0164] A: Water penetration time is between 0.10 seconds and 2.00 seconds. B: Water penetration time is 0.05 seconds or more but less than 0.10 seconds, or more than 2.00 seconds but less than 5.00 seconds C: Water penetration time is less than 0.05 seconds or more than 5.00 seconds

[0165] 7. Evaluation of the additive manufacturing object (evaluation of the shape accuracy of the additive manufacturing object) First, a rectangular parallelepiped-shaped additive manufacturing object was fabricated by binder jetting using the additive manufacturing powder of each sample number. The resulting additive manufacturing object measured 40 mm in length, 20 mm in width, and 5 mm in thickness. The binder solution used was a PVP aqueous solution containing 10% by mass of PVP, 12% by mass of a humectant, and the remainder being pure water.

[0166] The resulting layered object was then observed using a digital microscope that functions as a non-contact surface roughness measuring device. The arithmetic mean roughness Ra of the surface of the layered object was then measured based on the observation results. The shape accuracy of the layered object was then evaluated relative to the measurement results using the following evaluation criteria. The evaluation results are shown in Table 1.

[0167] A: The arithmetic mean roughness Ra is 4.0 μm or less (particularly high shape precision) B: The arithmetic mean roughness Ra is greater than 4.0 μm and less than 7.0 μm (shape accuracy is somewhat high) C: The arithmetic mean roughness Ra is greater than 7.0 μm and less than 10.0 μm (shape accuracy is somewhat low) D: Arithmetic mean roughness Ra is over 10.0 μm (shape accuracy is particularly low)

[0168] [Table 1]

[0169] As shown in Table 1, the powders for additive manufacturing in each example were found to have good packing properties and to be capable of forming powder layers with good water permeability. Furthermore, the additive manufacturing bodies in each example were found to have high shape accuracy. [Explanation of symbols]

[0170] 1... Powder for additive manufacturing, 2... Additive manufacturing apparatus, 4... Binder solution, 6... Additive manufacturing body, 11... Metal particles, 12... Coating, 13... Surface-coated particles, 21... Apparatus body, 22... Powder supply elevator, 23... Manufacturing stage, 24... Coater, 25... Roller, 26... Liquid supply unit, 31... Powder layer, 41... Binder layer, 60... Formation area, 211... Powder storage unit, 212... Manufacturing unit, P1... Waveform, P2... Waveform, P3... Waveform, S102... Powder layer formation process, S106... Binder solution supply process, S108... Repeating process, S110... Removal process, S202... Manufacturing process, S204... Sintering process, SP... Infrared absorption spectrum

Claims

1. A powder for additive manufacturing used in manufacturing an additive manufacturing body by binder jetting, Metal particles; a coating film provided on the surface of the metal particles and containing a compound derived from a silane coupling agent; Equipped with The silane coupling agent is a powder for additive manufacturing, characterized in that it is composed of a structural unit represented by the following formula (1): 【Chemical 1】 [In formula (1), R are functional groups that are independent of each other, and 50% or more of the functional groups R contain an organic group selected from the group consisting of a carboxy group, a hydroxy group, an amino group, and an epoxy group. n is the number of repeating units and is 0 or more and 10 or less.]

2. The powder for layered manufacturing according to claim 1 , wherein the number of repeating units n is 0 or more and 5 or less.

3. When subjected to infrared spectroscopic analysis, the obtained infrared absorption spectrum is Wave number 1120cm －１ 1140cm or more －１ Waveform P1 derived from the Si—O bond located below, and Wave number 2700cm －１ More than 3000cm －１ Waveform P2 derived from the C-H bond located below, and The powder for layered manufacturing according to claim 1 or 2, wherein the ratio P2 / P1 of the area of ​​waveform P2 to the area of ​​waveform P1 is 0.5 or less.

4. The silane coupling agent is diluted to a concentration of 0.3% by mass, applied to a glass substrate, and the resulting coating film is dried by heating at 100°C for 1 hour. The powder for additive manufacturing according to claim 1 or 2 is configured so that when the water contact angle of the resulting dried film is measured using a contact angle meter, the measured value is 30° or more and 90° or less.

5. The powder for additive manufacturing according to claim 1 or 2, wherein the average particle size of the metal particles is 1.0 μm or more and 15.0 μm or less.

6. The powder for additive manufacturing according to claim 1 or 2, a binder that binds particles of the powder for additive manufacturing together; A layered object comprising:

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