System and method for processing atomized powder, and processed powder

Abstract

To provide a method for removing ultrafine particles (206) from an atomized powder (306).SOLUTION: A method includes contacting the atomized powder (306) with a removal liquid (324), the atomized powder (306) comprising fine particles (202) and ultrafine particles (206), wherein contacting the atomized powder (306) with the removal liquid (324) comprises adding energy to a mixture (336) of the atomized powder (306) and the removal liquid (324) to detach the ultrafine particles (206) from the fine particles (202); and separating the removal liquid (324) and the ultrafine particles (206) from the fine particles (202).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a system and method for treating atomized powder, and the powder treated accordingly.

Background Art

[0002] Typically, the desired characteristics of high-quality reactive metal powder are a combination of high sphericity, density, purity, and fluidity. Fine reactive metal powder is beneficial for applications such as 3D printing, powder injection molding, hot isostatic pressing, and coating. Such fine powders are used in applications in the aerospace, biomedical, and industrial fields.

Summary of the Invention

Means for Solving the Problems

[0003] One aspect of the present disclosure is a method for removing ultrafine particles from atomized powder, comprising contacting the atomized powder with a removal liquid, the atomized powder including fine particles and ultrafine particles, and contacting the atomized powder with the removal liquid includes adding energy to a mixture of the atomized powder and the removal liquid to separate the ultrafine particles from the fine particles, and separating the removal liquid and the ultrafine particles from the fine particles.

Brief Description of the Drawings

[0004] [Figure 1] It is a schematic flowchart of a process according to an exemplary aspect of the present disclosure. [Figure 2] It is an enlarged view of a sample of atomized powder according to an exemplary aspect of the present disclosure. [Figure 3] It is an ultrafine particle removal system according to an exemplary aspect of the present disclosure. [Figure 4] It is an ultrafine particle removal system according to another exemplary aspect of the present disclosure. [Figure 5] It is an ultrafine particle removal system according to yet another exemplary aspect of the present disclosure. [Figure 6] It is a liquid classification system that can be incorporated into the ultrafine particle removal system of the present disclosure. [Figure 7] This is a table containing numerical values ​​corresponding to some of the exemplary powders shown in Figure 8. [Figure 8] This is a plot of powder according to one or more exemplary embodiments of the present disclosure. [Figure 9] This is a table of four examples of reactive metal powders illustrating the advantages of the processing described herein. [Modes for carrying out the invention]

[0005] A complete and possible disclosure of this disclosure, including its best mode, intended for those skilled in the art, is described herein with reference to the appended inventions.

[0006] Embodiments of the present disclosure are described in detail hereby shown in the accompanying drawings, with one or more examples being illustrated. In the detailed description, numerals and letters are used to refer to features in the drawings. Similar or analogous references in the drawings and description are used to refer to similar or analogous parts of the present disclosure.

[0007] The term “exemplary” is used herein to mean “acting as an example, case, or illustration,” and any implementation described herein as “exemplary” should not necessarily be interpreted as being preferable or advantageous to other implementations. Furthermore, unless otherwise specified, all embodiments described herein should be considered illustrative.

[0008] The singular form "one" or "one" usually refers to multiple things unless the context clearly indicates otherwise.

[0009] For example, in the context of "at least one of A, B, and C," the phrase "at least one of" refers to A only, B only, C only, or any combination of A, B, and C.

[0010] The terms "from X to Y" and "between X and Y" refer to a range of values ​​that includes the endpoint (i.e., a range of values ​​that includes both X and Y).

[0011] The term "particle size distribution" refers to powder in which at least 80% of the obtained powder has a particle size distribution between the lower and upper limits. This value is measured according to ASTM B214-22 for at least the upper cut, and optionally according to ASTM B822-20 for the lower cut.

[0012] As used herein, the term “reactive metal powder” refers to a metal powder formed from an oxygen-reactive metal, a nitrogen-reactive metal, or both. For example, the reactive metal powder may include at least one component selected from titanium, titanium alloys, zirconium, zirconium alloys, magnesium, magnesium alloys, cobalt, cobalt superalloys, nickel, nickel superalloys, niobium, niobium alloys, aluminum, aluminum alloys, molybdenum, molybdenum alloys, tungsten, or tungsten alloys.

[0013] As used herein, the term "untreated metal powder" refers to metal powder obtained directly from atomization without any post-processing steps such as sieving or classification techniques.

[0014] Referring to the drawings, the same numbers throughout the drawings represent the same elements, and Figure 1 is a flowchart of process 100 for processing a metal into finished metal powder. More specifically, in the illustrated embodiment, process 100 is for processing a reactive metal into finished reactive metal powder.

[0015] Process 100 includes, in 102, providing a metal from a metal source, and in 104, atomizing the metal provided in 102. The metal may be a reactive metal such as at least one of titanium, titanium alloys, zirconium, zirconium alloys, cobalt superalloys, nickel, nickel superalloys, magnesium, magnesium alloys, niobium, niobium alloys, aluminum, aluminum alloys, molybdenum, molybdenum alloys, tungsten, tungsten alloys, or a combination thereof. The metal provided in 102 may be in the form of metal wire, metal bar, metal powder, etc.

[0016] Atomizing a metal in 104 may include utilizing any suitable atomizing treatment. For example, in at least one exemplary embodiment, atomizing a metal in 104 may include atomizing a metal using a plasma atomizing treatment. In particular, in at least one exemplary embodiment of the present invention, atomizing a metal in 104 may include utilizing one or more of the exemplary plasma atomizing treatments described in U.S. Patent No. 11,198,179 issued on December 14, 2021, and / or U.S. Patent Application No. 2019 / 0001416 published on January 3, 2019. Each of the above is incorporated fully herein by reference for all purposes.

[0017] Therefore, in at least one exemplary embodiment of the present disclosure, atomizing a metal in 104 may include preheating the metal and feeding the preheated metal into a plasma stream provided by one or more plasma nozzles, thereby causing the plasma stream to overheat the preheated metal and crush it into a fine powder. Additive gases may be incorporated to provide a benefit to the fluidity of the resulting powder.

[0018] In other exemplary embodiments, other suitable atomization processes such as other suitable plasma atomization processes, gas atomization processes, skull melting gas atomization processes, electrode induction melting gas atomization processes (EIGA processes), and plasma rotating electrode processes may be utilized. Furthermore, it will be understood that, as used herein, the atomization of metal in 104 may additionally or alternatively include spheroidizing processes such as plasma (RF, DC, MW) spheroidizing processes, such as one or more of the exemplary spheroidizing processes described in U.S. Patent No. 11,235,385 issued February 1, 2022.

[0019] Untreated metal powder can be obtained by atomizing the metal in 104. Further referring to Figure 1, process 100 further includes sieving the untreated metal powder in 106 to obtain atomized powder having a certain particle size distribution. Sieving the untreated metal powder in 106 may include applying dry sieving or gas classification to the untreated metal powder, wet sieving the untreated metal powder, or a combination thereof. Dry sieving the untreated metal powder may include, for example, passing the untreated metal powder through one or more mesh sieves or filters while vibrating the untreated metal powder, a mesh sieve or filter, or both.

[0020] As described above, the atomized powder obtained from sieving in 106 can define a particle size distribution. In particular, the atomized powder achieved from sieving in 106 can define a particle size distribution from 0 micrometers (μm) to 150 μm. As used herein and in the context of sieving in 106, the term “particle size distribution” will be understood to have the definition provided above. The atomized powder can be achieved by passing the untreated metal powder through a first mesh sieve or filter designed to remove particles larger than the upper range of the particle size distribution (e.g., 150 μm in the embodiments described above), also called the upper cut size, and then optionally subjecting the untreated metal powder to a second filtering or classification step designed to remove particles smaller than the lower range of the particle size distribution (e.g., 10 μm in some embodiments). This lower limit is also called the lower cut size.

[0021] In other exemplary embodiments of the present disclosure, it will be understood that in 106, the atomized powder achieved by sieving may define a particle size distribution with a lower range of 0 μm to 75 μm, for example, 5 μm to 45 μm, for example, 7 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, 40 μm, 50 μm, 60 μm, or 70 μm. Furthermore, the atomized powder obtained by sieving may define a particle size distribution in 106 with an upper limit range of 20 μm to 150 μm, for example, 45 μm to 75 μm, for example, 40 μm, 53 μm, 65 μm, 75 μm, 85 μm, 95 μm, 105 μm, or 115 μm.

[0022] As can be further understood from the description herein, despite sieving, in 106 the atomized powder may further include ultrafine particles or satellites attached to the fine particles having a size within the particle size distribution. For example, referring briefly here to Figure 2, a magnified view of a sample 200 of atomized powder according to an exemplary embodiment of the present disclosure is provided. The atomized powder includes fine particles 202 that define a particle size within the particle size distribution. In particular, as used herein, the term “size” with respect to a particle refers to the maximum lateral measurement 204. For example, if the particle is a perfect sphere, the maximum lateral measurement 204 is the diameter of the sphere. The atomized powder further includes ultrafine particles 206 bound to the fine particles 202. In at least certain exemplary embodiments, the ultrafine particles 206 may define a size smaller than the particle size distribution (i.e., a size smaller than the lower limit of the particle size distribution). For example, in at least certain exemplary embodiments, the ultrafine particles 206 may define a size of 7 μm or less, for example, 5 μm or less.

[0023] It will be understood that the interaction between the ultrafine particles 206 and the fine particles 202 may prevent the ultrafine particles 206 from being removed from the resulting atomized powder during the sieving process. For example, in at least certain exemplary embodiments, a dipole-dipole or composite electrical interaction between one or more of the ultrafine particles 206 and one or more of the fine particles 202 may generate a cohesive force between them that may be stronger than the force exerted on the ultrafine particles 206 during the sieving process (see the sieving process in 106 in Figure 1).

[0024] If ultrafine particles 206 attached to fine particles 202 are present in the resulting atomized powder, the fluidity of the atomized powder may decrease due to increased coarseness of the fine particles and various electromagnetic interactions.

[0025] Referring again to Figure 1, in order to increase the fluidity of the atomized powder, process 100 further includes subjecting the atomized powder to an ultrafine particle removal process in 108 to produce treated atomized powder. The ultrafine particle removal process in which the atomized powder is treated in 108 is described in more detail below, for example, with reference to Figures 3 to 5. For example, as will be discussed in more detail below, the ultrafine particle removal process that the atomized powder undergoes in 108 may include exposing the atomized powder to a liquid, which is hereafter referred to herein as the removal liquid. Thus, process 100 in Figure 1 further includes drying the treated atomized powder in 110. Further details and exemplary methods for drying the atomized powder treated in 110 are also described in detail below.

[0026] The dried atomized powder, referred to herein as finished atomized powder, can then be packaged in 112 or otherwise placed into use.

[0027] In short, as shown by the dashed line in Figure 1, the step of sieving the untreated metal powder in 106 is provided in an exemplary embodiment of process 100 described above before removing the ultrafine particles 206 in 108 (see Figure 2), but in other embodiments, the step of sieving 106' after removing the ultrafine particles 206 in 108 may be additionally or alternatively included in process 100 of Figure 1.

[0028] Referring now to Figure 3, an exemplary embodiment of the ultrafine particle removal system 300 of this disclosure is schematically shown.

[0029] An exemplary ultrafine particle removal system 300 includes a container 302 defining a mixing cavity 304 for receiving atomizing powder 306. In particular, in the illustrated embodiment, the container 302 includes a door 308 that is rotatable around a hinge 310 (indicated by arrow 312) between a closed position (illustrated) and an open position (indicated by dashed line). When the door 308 is in the open position, the atomizing powder 306 may be added to or removed from the mixing cavity 304. When the door 308 is in the closed position, the door 308 can form a fluid seal with the rest of the container 302.

[0030] The atomized powder 306 can be generated during the execution of a process for processing a metal into a finished metal powder, such as the exemplary process 100 in Figure 1. Thus, the atomized powder 306 can be supplied to the mixing cavity 304 of the container 302 after the sieving step 314 to obtain atomized powder 306 with a defined particle size distribution.

[0031] The container 302 of the ultrafine particle removal system 300 in Figure 3 further includes an ultrafine particle filter 316 exposed to a mixing cavity 304. More specifically, in the illustrated embodiment, the mixing cavity 304 is positioned above the ultrafine particle filter 316 along a vertical direction V defined by the ultrafine particle removal system 300. As understood, the atomized powder includes fine particles having a size within the particle size distribution and ultrafine particles having a size which may be smaller than the particle size distribution (see particles 202, 206 in Figure 2). The ultrafine particle filter 316 defines a plurality of openings 318 defining a diameter 320 small enough to prevent particles larger than the ultrafine particles of the atomized powder 306 from passing through, as shown in the callout circle A. For example, in at least certain exemplary embodiments, the diameter 320 of the openings 318 may be 5 μm to 10 μm.

[0032] It will be understood that the ultrafine particle filter 316 can have any suitable configuration. In at least certain exemplary embodiments, the ultrafine particle filter 316 may be a porous metal filter. Such a porous metal filter has a nominal opening larger than the low cut size of the powder and can further preferentially filter out ultrafine particles depending on the pressure difference and thickness of the powder cake.

[0033] As described above, the attractive forces between the ultrafine particles and fine particles of the atomized powder 306 may be strong enough to resist mechanical sieving. Therefore, the ultrafine particle removal system 300 in Figure 3 further includes a fluid nozzle 322 that is in fluid communication with the mixing cavity 304 to provide the removal liquid 324 (see Figure 4, described later) to the mixing cavity 304. As will be described in more detail below, the removal liquid 324 may be water, a fluorocarbon liquid, a halocarbon liquid, an organic solvent or an inorganic solvent, or a combination thereof. One criterion for the selection of the liquid should be that it does not chemically react with the powder in order to maintain the original purity of the powder.

[0034] The container 302 further defines an outlet 326 located downstream of the ultrafine particle filter 316 from the fluid nozzle 322, and the ultrafine particle removal system 300 further includes a recirculation assembly 328, the recirculation loop 330 (e.g., formed by one or more conduits) which is fluidly coupled to the outlet 326 and thus fluidly coupled to a mixing cavity 304 located downstream of the ultrafine particle filter 316. The recirculation assembly 328 is further fluidly coupled to the fluid nozzle 322 and recirculates the removal liquid 324 received therethrough.

[0035] In particular, the illustrated embodiment further includes a pump 332 that generates a pressure difference to facilitate fluid flow through the recirculation loop 330 of the recirculation assembly 328, and a particulate filter 334. The particulate filter 334 may be configured to extract particles smaller than, for example, 1 μm, as will be described in more detail below.

[0036] Referring now to Figure 4, an exemplary ultrafine particle removal system 300 of Figure 3 is depicted in operation. In particular, during operation, the ultrafine particle removal system 300 is configured to bring the atomized powder 306 (see Figure 3) received in the mixing cavity 304 of the container 302 into contact with the removal liquid 324 to form a mixture 336 of the atomized powder 306 (see Figure 3) and the removal liquid 324. In the illustrated embodiment, the ultrafine particle removal system 300 is further configured to add energy to the mixture 336. As described above, the atomized powder 306 contains fine particles and ultrafine particles (see particles 202 and 206 in Figure 2), and by adding energy to the mixture 336, it becomes easier to separate the ultrafine particles from the fine particles in the mixture 336.

[0037] In the embodiment shown in Figure 4, applying energy to the mixture 336 includes, for example, spraying the removal liquid 324 onto the atomizing powder 306 using a fluid nozzle 322 at a pressure higher than the ambient pressure (e.g., 5 pounds / square inch (psi) to 250 psi, e.g., 10 psi to 100 psi).

[0038] Furthermore, in the illustrated embodiment, adding energy to the mixture 336 further includes exposing the mixture 336 to ultrasonic energy. In particular, the illustrated embodiment further includes an ultrasonic probe 338 extending into the mixing cavity 304 at a position where the ultrafine particle removal system 300 interacts with the mixture 336. The ultrasonic probe 338 is operably connected to a power source 340 so that, in response to a command, the ultrasonic probe 338 can be provided with sufficient power to deliver ultrasonic energy to the mixture 336 of the atomized powder 306 and the removal liquid 324.

[0039] However, it will be understood that in other exemplary embodiments, energy may be added to the mixture 336 of the atomizing powder 306 (see Figure 3) and the removal liquid 324 in any other suitable manner. For example, with brief reference to Figure 5, an ultrafine particle removal system 300 according to another exemplary embodiment of the present disclosure is provided. The exemplary ultrafine particle removal system 300 of Figure 5 can be configured in substantially the same manner as the ultrafine particle removal system 300 of Figure 4, and the same or similar numbers may refer to the same or similar parts. However, in the embodiment of Figure 5, instead of the ultrasonic probe 338, the ultrafine particle removal system 300 includes a mixer 342 positioned in a mixing cavity 304 to add energy to the mixture 336 of the atomizing powder 306 (see Figure 3) and the removal liquid 324. The mixer 342 includes one or more paddles 344, more specifically a plurality of paddles 344 mounted on a shaft 346 configured to rotate around the axis of the shaft 346 to add energy to the mixture 336. Multiple paddles 346 generate centrifugal force, which can also be generated by the swirling flow of the liquid. The ultrafine particle removal system 300 in Figure 5 further includes a power supply 348 operably coupled to the mixer 342 to supply power to the mixer 342.

[0040] In addition, or alternatively, in other exemplary embodiments, energy may be added to the mixture 336 using a liquid classification system. Briefly referring here to Figure 6, a schematic diagram of a liquid classification system 370 that may be incorporated into the ultrafine particulate removal system 300 of the present disclosure (e.g., one or more of the ultrafine particulate removal systems 300 described above) is provided. The liquid classification system 370 of Figure 6 utilizes centrifugal force such that the removal liquid 324 is introduced through an inlet 372 together with the atomized powder 306 (see Figure 3) and the mixture 336 is swirled within the cylindrical body 374 of the liquid classification system 370 (see arrow 380). The first outlet 376 of the liquid classification system 370 is located below the second outlet 378 of the liquid classification system 370 along the vertical direction V, so that coarser particles can be received through the first outlet 376 and a mixture of ultrafine particles and the removal liquid can be received through the second outlet 378.

[0041] It will be understood that the liquid classification system 370 shown in Figure 6 is provided for illustrative purposes only. In other exemplary embodiments, other suitable liquid classification systems may be used in the ultrafine particle removal system 300 of this disclosure.

[0042] Referring again to Figure 4, it should be understood that by bringing the atomized powder 306 (see Figure 3) into contact with the removal liquid 324, the removal liquid 324 can shield the electrical interactions (such as dipole-dipole interactions) between the ultrafine particles and the fine particles of the atomized powder 306 (see particles 202 and 206 in Figure 2). In particular, the removal liquid 324 can define an electrical dielectric constant that shields the electrical interactions (e.g., dipole-dipole interactions) between the ultrafine particles and the fine particles, and as a result, the ultrafine particles can be more easily desorbed by adding energy to the mixture 336. It should be further understood that adding energy to the mixture 336 of atomized powder 306 and removal liquid 324 can promote the removal of ultrafine particles from the fine particles of the atomized powder 306, and as a result, the ultrafine particles are suspended in the removal liquid 324 within the mixture 336.

[0043] The ultrafine particle removal system 300 is further configured to separate the removal liquid 324 after energy has been added to the mixture 336, thereby separating ultrafine particles from fine particles. As shown by the dashed line in Figure 4 and schematically shown in more detail by the callout circle B in Figure 4, the container 302 further includes a blocker layer 350 that selectively fluidically isolates the ultrafine particle filter 316 from the mixing cavity 304. In the illustrated exemplary embodiment, the blocker layer 350 includes a wall 352 defining a plurality of openings 354 and a plurality of flapper valve doors 356, each positioned inside each of the plurality of openings 354. Each flapper valve door 356 may be swiveling between an open position (shown by the dashed line) that allows fluid flow through the opening 354 and a closed position that prevents fluid flow through the opening 354.

[0044] In this way, it will be understood that the blocker layer 350 can allow the ultrafine particle removal system 300 to separate the removal liquid 324 and add a desired amount of energy to the mixture 336 of atomized powder 306 (see Figure 3) and the removal liquid 324 before separating the ultrafine particles from the fine particles.

[0045] In the embodiment shown in Figure 4, separating the removal liquid 324 and the separated ultrafine particles from the fine particles may include the removal liquid 324 and the separated ultrafine particles flowing through the ultrafine particle filter 316 of the container 302 and through the outlet 326 to the recirculation assembly 328, as indicated by arrow 358 (representing the mixture of removal liquid 324 and ultrafine particles). As described above, the recirculation assembly 328 includes a fine particle filter 334 that can remove ultrafine particles from the mixture 358, leaving the removal liquid 324 that can be reused in the ultrafine particle removal system 300. In this way, it will be understood that the removal liquid 324 can be filtered to remove the ultrafine particles separated from the removal liquid 324 in the recirculation loop 330 of the recirculation assembly 328, and the filtered removal liquid 324 can then be supplied to the same or a second group of atomizing powders (not shown). As a result, waste may be reduced during the operation of the ultrafine particle removal system 300.

[0046] In short, the ultrafine particle removal system 300 further includes a recirculation assembly 328 and a source 360 ​​of removal liquid 324 that is in fluid communication with the fluid nozzle 322, ensuring that a sufficient amount of removal liquid 324 is available for the ultrafine particle removal process.

[0047] After separating the removal liquid 324 and the ultrafine particles from the fine particles, the fine particles can be removed (for example, through the door 308 of the container 302) and dried using the drying apparatus 362. The drying apparatus 362 may be a vacuum drying apparatus that exposes the fine particles from the ultrafine particle removal system 300 to a vacuum environment (pressure below atmospheric pressure) and controls the atmosphere and temperature to which the fine particles are exposed. A heat furnace can also be used to dry the powder.

[0048] It should be understood that removing ultrafine particles using the ultrafine particle removal system 300 may not result in a substantial reduction in the mass of the atomized powder 306 (see Figure 3), given the size of the ultrafine particles. For example, the particles may be referred to as finished metal powder after drying using the drying apparatus 362, and the mass of the finished metal powder M Finish The atomized powder 306 provided to the ultrafine particle removal system 300 (see Figure 3) has an initial mass M before the ultrafine particles are removed. Initial The finished metal powder mass M may be defined. Finish The initial mass M Initial The ratio to may be 0.90 or higher, for example, 0.95 or higher. Therefore, the process of removing ultrafine particles from the atomized powder 306 may not result in a substantial reduction in the mass of the finished metal powder.

[0049] In particular, when the ultrafine removal process described herein is used in conjunction with a wet sieving process in the same apparatus, the finished metal powder mass M Finish It is practically low (for example, the finished metal powder mass M) Finish The initial mass M Initial The ratio to is less than 0.85 (for example, it may be less than 0.8), and it will be understood that this is influenced by two processes during insertion into the cavity and drying.

[0050] As briefly described above, the removal solution 324 may be water or an organic or inorganic solvent. In addition, or alternatively, if the reactive metal powder is a reactive metal powder that does not react well with water, the removal solution 324 may be an organic or inorganic solvent, a halocarbon liquid, or a fluorocarbon liquid. For example, in certain exemplary embodiments, the reactive metal powder may include aluminum or an aluminum alloy, and the removal solution may be a halocarbon liquid to prevent the powder from reacting with water.

[0051] Halocarbon liquids, such as fluorocarbon liquids, have the advantage of avoiding reaction or corrosion with reactive metal powders. Halocarbon liquids also generally have relatively low boiling points, and as a result, they can evaporate relatively quickly from reactive metal powders after processing. Examples of fluorocarbon liquids according to various aspects of the present invention include Novec TM Examples include hydrofluorocarbons and fluorinated ketones.

[0052] In addition, the present disclosure further provides a method for removing ultrafine particles from atomized powder. This method may be included as part of process 100 in Figure 1, used in conjunction with the ultrafine particle removal system 300 in Figures 3 to 5, or included as part of or used in conjunction with any other suitable process or system.

[0053] The method comprises (a) contacting atomizing powder with a removal solution to form a mixture of atomizing powder and removal solution. The atomizing powder includes fine particles and ultrafine particles. In at least certain exemplary embodiments, the atomizing powder does not have to contain dopants and / or flow enhancers or adhering molecules that reduce the hydrophilicity of the particles. Such hydrophilic-reducing binding molecules are described, for example, in Canadian Patent Application CA3138388. The atomizing powder of this disclosure does not involve intentional elemental addition as referred to by ASTMF 1580-18 or compositional doping as referred to by AMS 7002A.

[0054] The method further comprises (b) adding energy to a mixture of atomized powder and removal liquid in order to separate ultrafine particles from fine particles.

[0055] In certain exemplary embodiments, the application of energy to the mixture of atomizing powder and removal liquid in (b) includes exposing the mixture to ultrasonic energy, mechanically agitating the mixture (e.g., mixing or stirring the mixture), or both. In additional or alternative exemplary embodiments, the application of energy to the mixture of atomizing powder and removal liquid in (b) includes atomizing the pressurized removal liquid with the atomizing powder.

[0056] This method further includes separating the removal solution from the ultrafine particles separated from the fine particles in (c).

[0057] The method may further include (d) classifying or sieving the unprocessed atomized powder in order to obtain the atomized powder before contacting the atomized powder with the removal solution.

[0058] In certain exemplary embodiments, the atomized powder may be a first batch of atomized powder, and the method may further include (e) receiving the separated removal liquid and separated ultrafine particles in a recirculation loop, (f) filtering the ultrafine particles separated from the removal liquid in a recirculation loop, and (g) returning the filtered removal liquid to the first batch of atomized powder or a second batch of atomized powder.

[0059] According to conventional thinking, exposing reactive metal powders to moisture has been considered undesirable. This is because moisture is generally thought to increase the cohesive force between fine particles, particularly between ultrafine particles and fine particles. Thus, conventional thinking dictates that exposing reactive metal powders to moisture would reduce the fluidity of the resulting powder. However, the inventors of this disclosure have discovered, beyond expectations, that by exposing reactive metal powders to a sufficient amount of a removal solution to form a mixture of the reactive metal powders and the removal solution, and then adding energy to the mixture, ultrafine particles can actually be removed from the fine particles. Furthermore, they have discovered that such removal of ultrafine particles can significantly improve the fluidity of the reactive metal powder after drying.

[0060] In particular, a common measure for the flowability of the powder (i.e., its fluidity, F RMP ) is by use of the Hall test according to ASTM B213-20. The removal of ultrafine particles from the atomized powder according to the present invention has been found to provide a significant advantage to the fluidity F RMP of the resulting powder. An increase in the fluidity F RMP can provide significant benefits, for example, in the additive manufacturing industry and other industries.

[0061] The inventors have found that both the size S RMP of the particles of the finished metal powder (and the average mass M RMP of each particle having the size S C ) and the apparent density, D RMP of the finished metal powder affect the volume fluidity F VRMP of the finished metal powder. For example, larger fine particles generally have improved volume fluidity F VRMP compared to smaller powders having similar properties, and more dense finished metal powders also generally have improved fluidity F RMP compared to less dense finished metal powders having similar properties.

[0062] For example, in order to function in a desired manner in an additive manufacturing machine, the inventors have found that a minimum volume fluidity F VRMP should be achieved. These volume fluidities F VRMP can be achieved using the improvements associated with the processes and methods described herein. Finished metal powders exhibiting fluidity characteristics below these thresholds may not be able to function in the desired manner and may, for example, cause jamming or slow down production using the powder. The relationship between the volume fluidity F VRMP of the alloys found by the inventors to have the above-described effects, the size S<00000​​​​​​​​​

[0063] F VRMP ≥0.3 × ln(M C )+2

[0064] M C Size S RMP This is the average mass of the particles, ranging from 0.001 micrograms to 1 microgram. C This is obtained by calculating the mass of a sphere with a radius equal to half the size of the SRMP, and the density is the bulk density D of the alloy. BULK It is equal to M C This can be found using the following relationship:

[0065]

number

[0066] S RMP The D10 value (defined as the point below which 10% of particles are located in the particle size distribution curve measured according to ASTM B822-20) is between 5 micrometers and 30 micrometers. The instrument used to carry out the measurement method is a Beckman Coulter LS 13 320. BULK is the bulk density of the alloy, which can be obtained by ASTM B923-22. In relation to the above, D BULK The amount is 1.5-20 g / cm³. 3 This may be the case. There are various instruments that can be used for particle size determination by laser diffraction in accordance with ASTM B822-20. These include Beckman Coulter TM LS 13 320, Cilas990L TM Malvern TM Mastersizer TM , Sympatec TM HELOS TM Microtrac TM Particle size analyzer S3500 TMThis includes, among others. As should be understood, there may be inherent variability in the D10 values ​​obtained from specific powders tested using equipment available under the guidance of ASTM B822-20. For the purposes of this disclosure, the range of D10 values ​​provided herein is intended to refer to powders exhibiting D10 values ​​within the disclosed and / or claimed range when tested using at least one of the approved methods and equipment in accordance with ASTM B822-20.

[0067] F VRMP It is a volumetric fluidity, ranging from 0.1 cubic centimeters / second to 1.4 cubic centimeters / second. VRMP This refers to the time (F) required for 50 grams of powder used in a whole flow test (according to ASTM B213-20) to flow through a funnel. HFT Volumetric flow rate F is obtained by dividing by (expressed in seconds) and then by the apparent density, expressed in grams / cubic centimeter, and obtained according to ASTM B212-21. VRMP The final unit is cubic centimeters divided by seconds. Measured according to ASTM B212-21. RMP It ranges from 0.8 grams / cubic centimeter to 11 grams / cubic centimeter. In particular, F VRMP This can be found using the following relationship:

[0068]

number

[0069] Referring here to Figures 7 and 8, various exemplary powders according to one or more exemplary embodiments of the present disclosure are shown. In particular, Figure 7 provides a table containing numerical values ​​corresponding to some of the exemplary powders in Figure 8. Figure 8 is a graph 400 of powders according to one or more exemplary embodiments of the present invention, with volumetric fluidity F on the Y axis 402. VRMP And the particle size S on the X-axis 404 RMP Average mass M C This indicates that.

[0070] As shown in the diagram, plot 400 in Figure 8 represents the fluidity F VRMP 0.3 × ln(M C ) + 2 (line 408) or more and 0.3 ln (M C The first range 406 is drawn, which is less than or equal to ) + 2.4 (line 410).

[0071] In the exemplary embodiment shown in Figure 8, the powder has a volume fluidity F of 0.35 to 1.05. VRMP Titanium alloys having (Ti-6Al-4V, etc.); volumetric fluidity F of 0.7 to 1.1 VRMP Nickel or nickel alloy having volume fluidity F of 1.0 to 1.2 VRMP Niobium or niobium alloy having ; and volumetric fluidity F of 0.2 to 0.5 VRMP Includes aluminum or aluminum alloys having the properties of aluminum.

[0072] Referring now to Figure 9, a table is shown of four examples of reactive metal powders illustrating the advantages of the process of this disclosure.

[0073] Example 1. The first lot was a titanium alloy and included a first batch of atomized powder before ultrafine particle removal and a second batch of atomized powder after ultrafine particle removal. The ultrafine particle removal process for this example included mixing the atomized powder with water, applying ultrasonic energy, and straining across a 15-micrometer mesh. As observed, the ultrafine particle removal process resulted in a slight increase in D10 (increase rate greater than 0%, less than 10%, e.g., less than 5%), a slight decrease in the proportion of particles smaller than 10 microns, and a significant increase in fluidity (improvement from 10% to 100%, e.g., improvement from 25% to 50%).

[0074] Example 2. The second batch of nickel alloy was processed in the same way as the first batch (however, specifically, the ultrafine particle removal process resulted in a slight increase in D10 (increase rate greater than 0%, less than 10%), a slight decrease in the proportion of particles smaller than 10 microns, and a significant increase in fluidity (between a 10% improvement and a 100% improvement).

[0075] Example 3. The third lot of niobium alloy was processed in the same manner as the first lot (except for a slightly different nominal size / particle size distribution). The results were similar. Specifically, the ultrafine particle removal process resulted in a slight increase in D10 (increase rate greater than 0%, less than 10%, e.g., less than 5%), no measurable change in the proportion of particles smaller than 10 microns, and a significant increase in fluidity (between a 10% improvement and a 100% improvement).

[0076] Example 4. The fourth lot, an aluminum alloy, similarly contained the first batch of atomized powder before ultrafine particle removal and the second batch of atomized powder after ultrafine particle removal. The ultrafine particle removal process in this example involved spraying the atomized powder with fluorine carbon solution and filtering it through a 20-micron mesh. Thus, it can be seen that the mixture of atomized powder and removal solution (fluorine carbon solution in Example 4) was filtered through a mesh smaller than the lower limit of the particle size distribution of the atomized powder under test. As can be seen, the ultrafine particle removal process resulted in a slight increase in D10 (increase of 0% or more and increase of less than 20%), a decrease in the proportion of particles smaller than 10 microns, and a significant increase in fluidity (improvement of 10% or more and improvement of 100% or more, e.g., improvement of 25% or more and improvement of 50% or more).

[0077] Thus, it will be understood that the D10 value is substantially unaffected by the ultrafine powder removal process.

[0078] Further aspects are provided by the subject of the following sections:

[0079] A method for removing ultrafine particles from atomized powder, comprising contacting the atomized powder with a removal liquid, wherein the atomized powder comprises fine particles and ultrafine particles, and the contact of the atomized powder with the removal liquid includes adding energy to a mixture of the atomized powder and the removal liquid to separate the ultrafine particles from the fine particles, thereby separating the removal liquid and the ultrafine particles from the fine particles.

[0080] The method described above, wherein the atomized powder has a particle size distribution of 0 micrometers to 150 micrometers.

[0081] The method, wherein the atomized powder is a reactive metal powder.

[0082] The method wherein the reactive metal powder includes titanium, titanium alloys, zirconium, zirconium alloys, magnesium, magnesium alloys, aluminum and aluminum alloys, nickel and nickel alloys, niobium, niobium alloys, or combinations thereof.

[0083] The reactive metal powder is aluminum or an aluminum alloy.

[0084] The method wherein the removal liquid is a halocarbon liquid.

[0085] Any of the above methods further comprises sieving the untreated metal powder to obtain the atomized powder before bringing the atomized powder into contact with the removal liquid.

[0086] The method comprising sieving the untreated atomized powder by sieving the untreated metal powder by dry sieving or by wet sieving.

[0087] Adding energy to the mixture of the atomizing powder and the removal liquid is any of the methods described above, including exposing the mixture to ultrasonic energy, mechanically agitating the mixture, adding kinetic energy from a fluid flow, or a combination thereof.

[0088] The method of adding energy to a mixture of the atomizing powder and the removal liquid includes spraying the removal liquid onto the atomizing powder.

[0089] The method wherein the removal solution is water, an organic solvent or inorganic solvent, a halocarbon liquid, a fluorocarbon liquid, or a combination thereof.

[0090] The fine particles have a finished mass M Finish A finished metal powder is formed that defines the atomizing powder, and before the atomizing powder comes into contact with the removal liquid, the initial mass M Initial Define M Finish and M Initial Any of the above methods, wherein the ratio to exceeds 0.90.

[0091] The method further comprises the following steps: the atomizing powder is a first batch atomizing powder, and the method receiving the separated removal liquid and ultrafine particles in a recirculation loop, filtering the ultrafine particles from the removal liquid in the recirculation loop, and providing the filtered removal liquid to the first batch atomizing powder or to the second batch atomizing powder.

[0092] The method of applying energy to a mixture of the atomizing powder and the removal liquid includes exposing the mixture to ultrasonic energy.

[0093] The method of adding energy to the mixture of the atomizing powder and the removal liquid includes mechanically stirring the mixture.

[0094] Adding energy to the mixture of the atomizing powder and the removal liquid is any of the methods described above, including adding kinetic energy from the fluid flow.

[0095] A particulate removal system comprising: a container defining a mixing cavity for receiving atomized powder, further comprising an ultrafine particle filter exposed to the mixing cavity; a fluid nozzle fluidly communicating with the mixing cavity to provide a removal liquid to the mixing cavity; and a recirculation assembly fluidly coupled to the mixing cavity downstream of the ultrafine particle filter and further fluidly coupled to the fluid nozzle, wherein the recirculation assembly comprises a microfilter for removing ultrafine particles from a mixture received from the mixing cavity.

[0096] The aforementioned ultrafine particle removal system wherein the atomized powder defines a particle size distribution of 0 micrometers to 150 micrometers.

[0097] Any of the ultrafine particle removal systems further comprising an ultrasonic probe operably connected to a power supply, wherein, in response to a command, the ultrasonic probe is configured to provide ultrasonic energy to the mixture of the atomizing powder and the removal liquid.

[0098] Any of the ultrafine particle removal systems further comprising a mixer disposed within the mixing cavity and adding energy to a mixture of atomized powder and removal liquid.

[0099] Any of the ultrafine particle removal systems, wherein the mixer includes one or more paddles and a shaft, and one or more of the paddles are attached to the shaft and configured to rotate around the axis of the shaft to add energy to the mixture.

[0100] An ultrafine particle removal system, wherein the ultrafine particle filter defines multiple apertures that define diameters of 5 μm to 10 μm.

[0101] The container further comprises a blocker layer that selectively and fluidly isolates the ultrafine particle filter from the mixing cavity, the blocker layer comprising a wall defining a plurality of openings and a plurality of flapper valve doors, each positioned over each of the plurality of openings, in any of the ultrafine particle removal systems.

[0102] A atomized powder mixture comprising reactive metal powder, which includes fine powder formed from a reactive metal, wherein the reactive metal powder has a volumetric fluidity F measured according to ASTM B213-20. VRMP (cubic centimeters / second) and bulk density D BULK(grams / cubic centimeter) is defined, and the size S of the particles of the reactive metal powder corresponds to the D10 value of the reactive metal powder measured according to ASTM B822-20. RMP (micrometers) and average mass M C (micrograms) is defined, and volumetric fluidity F VRMP 0.3 × ln(M C ) + 2 or more, M C but

[0103]

number

[0104] In order to remove ultrafine metal powder from the fine powder, the reactive metal powder is treated as follows: RMP The size is 5 micrometers to 30 micrometers, and F VRMP The flow rate is 0.1 cubic centimeters / second to 1.4 cubic centimeters / second, and D BULK A atomized powder mixture with a concentration of 1.5 grams / cubic centimeter to 20 grams / cubic centimeter.

[0105] The atomized powder mixture is any of the above, wherein the reactive metal powder includes titanium, titanium alloys, zirconium, zirconium alloys, magnesium, magnesium alloys, aluminum, aluminum alloys, nickel, nickel alloys, niobium, niobium alloys, or a combination thereof.

[0106] The atomized powder mixture, wherein the reactive metal powder defines a particle size distribution of 0 micrometers to 150 micrometers.

[0107] Said F VRMP However, 0.3 × ln(M C Any of the atomized powder mixtures mentioned above, having a pH of 2.4 or less.

[0108] The apparent density D of the reactive metal powder is measured according to ASTM B212-21. RMP Define (grams / cubic centimeter), DRMP Any of the atomized powder mixtures having a concentration of 0.8 to 11 grams / cubic centimeter.

[0109] The reactive metal powder has a whole flow test fluidity F HFT The volumetric fluidity F is defined as follows: VRMP but

[0110]

number

[0111] The atomized powder mixture of any of the above.

[0112] A mixture of atomized powders formed using any of the above methods.

[0113] A atomized powder mixture formed using any of the aforementioned ultrafine particle removal systems.

[0114] This specification uses examples to disclose the disclosure, including the best mode, and enables any person skilled in the art to implement the disclosure, including making and using any device or system, and implementing any incorporated method. The patentable scope of the disclosure is defined by the claims and may include other examples that are recalled by a person skilled in the art. Such other examples are intended to be within the claims if they include structural elements that are not different from the literal language of the claims, or if they include equivalent structural elements that are substantially different from the literal language of the claims.

Claims

1. A method for removing ultrafine particles (206) from atomized powder (306), The atomizing powder (306) and the removal liquid (324) are brought into contact. The atomizing powder (306) comprises fine particles (202) and ultrafine particles (206). The fine particles are a titanium alloy with a particle size distribution of 15-45 μm, a nickel alloy with a particle size distribution of 15-53 μm, a niobium alloy with a particle size distribution of 15-53 μm, or an aluminum alloy with a particle size distribution of 25-63 μm. The ultrafine particles are smaller in size than the lower limit of the particle size distribution. Bringing the atomizing powder (306) and the removal liquid (324) into contact is The process involves adding energy to a mixture (336) of the atomizing powder (306) and the removal liquid (324) so ​​as to separate the ultrafine particles (206) from the fine particles (202), The removal liquid (324) and the ultrafine particles (206) are separated from the fine particles (202). The atomizing powder (306) is a reactive metal powder. The removal solution (324) is water, an organic solvent or inorganic solvent, a halocarbon liquid, a fluorocarbon liquid, or a combination thereof. Ultrafine particle removal method.

2. The method for removing ultrafine particles according to claim 1, wherein the atomized powder (306) defines a particle size distribution of 0 micrometers to 150 micrometers.

3. The reactive metal powder is an aluminum alloy. The removal liquid (324) is a halocarbon liquid. The method for removing ultrafine particles according to claim 1.

4. The process further includes sieving the untreated metal powder in order to obtain the atomized powder (306) before bringing the atomized powder (306) into contact with the removal liquid (324). The method for removing ultrafine particles according to claim 1.

5. The process of sieving the untreated metal powder includes sieving the untreated metal powder through a dry sieve or sieving the untreated metal powder through a wet sieve. The method for removing ultrafine particles according to claim 4.

6. The method for removing ultrafine particles according to claim 1, wherein adding energy to the mixture (336) of the atomizing powder (306) and the removal liquid (324) includes exposing the mixture (336) to ultrasonic energy, mechanically stirring the mixture (336), adding kinetic energy from a fluid flow, or a combination thereof.

7. The fine particles (202) have a finished mass M Ｆｉｎｉｓｈ A dried finished metal powder is formed that defines the shape. Before the ultrafine particles (206) are removed, the atomized powder (306) comes into contact with the removal liquid (324), and the initial mass M Ｉｎｉｔｉａｌ Define the area, M Ｉｎｉｔｉａｌ M for Ｆｉｎｉｓｈ The ratio exceeds 0.

90. The method for removing ultrafine particles according to claim 1.

8. The atomizing powder (306) is the first batch atomizing powder (306), The above-mentioned method for removing ultrafine particles is In the recirculation loop, the separated removal liquid (324) and ultrafine particles (206) are received. In the recirculation loop, the ultrafine particles (206) are filtered from the removal liquid (324). The filtered removal liquid (324) is provided to the first batch atomized powder (306) or the second batch atomized powder (306). This further includes, The method for removing ultrafine particles according to claim 1.

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