System and method for atomized powder processing 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 processing atomized powders, and to powders processed accordingly. [Background technology]

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

[0003] One aspect of the present disclosure is an ultrafine particle removal method for removing ultrafine particles from an atomized powder, comprising contacting the atomized powder with a removal liquid, the atomized powder containing 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 so as 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] 1 is a schematic flow diagram of a process according to an exemplary aspect of the present disclosure. [Diagram 2] FIG. 2 is a close-up view of a sample of atomized powder according to an exemplary embodiment of the present disclosure. [Diagram 3] 1 is an ultrafine particle removal system according to an exemplary embodiment of the present disclosure. [Figure 4] 1 is an ultrafine particle removal system according to another exemplary embodiment of the present disclosure. [Diagram 5] 1 is an ultrafine particle removal system according to yet another exemplary embodiment of the present disclosure. [Figure 6] 1 is a liquid classification system that may be incorporated into the ultrafine particle removal system of the present disclosure. [Figure 7] 9 is a table containing numerical values ​​corresponding to some of the example powders of FIG. 8. [Figure 8] 1 is a plot of a powder according to one or more exemplary embodiments of the present disclosure. [Figure 9] 1 is a table of four example reactive metal powders illustrating the processing advantages of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0005] A full and enabling disclosure of this disclosure, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in this specification, with reference to the appended claims.

[0006] Reference will now be made in detail to the embodiments of the present disclosure, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description are used to refer to like or similar parts of the present disclosure.

[0007] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration," and any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. Moreover, unless expressly stated otherwise, all embodiments described herein should be considered exemplary.

[0008] The singular forms "a," "an," and the like include plural references unless the context clearly dictates otherwise.

[0009] For example, the word "at least one of" in the context of "at least one of A, B, and C" 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" each refer to a range of values ​​that includes the endpoints (i.e., a range of values ​​that includes both X and Y).

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

[0012] As used herein, the phrase "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 member selected from one of 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 "unprocessed metal powder" refers to metal powder obtained directly from the atomization process, without post-processing steps such as sieving or classification techniques.

[0014] Referring now to the drawings, in which identical numerals refer to the same elements throughout, Figure 1 is a flow diagram of a process 100 for converting metal into a finished metal powder. More specifically, in the illustrated embodiment, the process 100 is for treating a reactive metal into a finished reactive metal powder.

[0015] The process 100 includes providing a metal from a metal source at 102 and atomizing the metal provided at 102 at 104. 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 combinations thereof. The metal provided at 102 may be in the form of a metal wire, a metal bar, a metal powder, or the like.

[0016] Atomizing the metal at 104 may include utilizing any suitable atomization process. For example, in at least one exemplary embodiment, atomizing the metal at 104 may include atomizing the metal using a plasma atomization process. In particular, in at least one exemplary embodiment of the present invention, atomizing the metal at 104 may include utilizing one or more of the exemplary plasma atomization processes described in U.S. Pat. No. 11,198,179, issued Dec. 14, 2021, and / or U.S. Patent Application No. 2019 / 0001416, published Jan. 3, 2019, each of which is incorporated herein by reference in its entirety for all purposes.

[0017] It will thus be appreciated that in at least one exemplary embodiment of the present disclosure, atomizing the metal at 104 may include preheating the metal and feeding the preheated metal into a plasma stream provided by one or more plasma nozzles, whereby the plasma stream superheats and breaks down the preheated metal into a fine powder. An additive gas may be incorporated to provide benefits to the flowability of the resulting powder.

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

[0019] A green metal powder can be obtained by atomizing the metal at 104. Still referring to FIG. 1, the process 100 further includes sieving the green metal powder at 106 to obtain an atomized powder having a particle size distribution. Sieving the green metal powder at 106 can include applying dry sieving or gas classification to the green metal powder, wet sieving the green metal powder, or a combination thereof. Dry sieving the green metal powder can include, for example, passing the green metal powder through one or more mesh sieves or filters while applying vibration to the green metal powder, the mesh sieves or filters, or both.

[0020] As mentioned above, the atomized powder resulting from sieving at 106 may define a particle size distribution. In particular, the atomized powder resulting from sieving at 106 may define a particle size distribution from 0 micrometers (μm) to 150 μm. As used herein, and in the context of sieving at 106, the term "particle size distribution" will be understood to have the definition provided above. The atomized powder may be achieved by passing the raw 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 above embodiments), also referred to as the upper cut size, and then optionally subjecting the raw 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 referred to as the lower cut size.

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

[0022] As will be further understood from the description herein, despite sieving, at 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 now briefly to FIG. 2, a close-up view of a sample 200 of an 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 that are attached 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, such as 5 μm or less.

[0023] It will be appreciated that interactions 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, dipole-dipole or complex electric interactions between one or more of the ultrafine particles 206 and one or more of the fine particles 202 may generate cohesive forces therebetween that may be stronger than the forces exerted on the ultrafine particles 206 during the sieving process (see sieving process at 106 in FIG. 1 ).

[0024] If the ultrafine particles 206 adhering to the fine particles 202 are present in the obtained atomized powder, the flowability of the atomized powder may decrease due to an increase in the coarseness of the fine particles and various electromagnetic interactions.

[0025] Referring again to FIG. 1, to enhance the flowability of the atomized powder, the process 100 further includes subjecting the atomized powder to an ultrafine particle removal process at 108 to produce a treated atomized powder. The ultrafine particle removal process by which the atomized powder is treated at 108 is described in more detail below, for example, with reference to FIGS. 3-5. For example, as discussed in more detail below, the ultrafine particle removal process to which the atomized powder is subjected at 108 may include exposing the atomized powder to a liquid, hereinafter referred to as the removal liquid. Thus, the process 100 of FIG. 1 further includes drying the treated atomized powder at 110. Further details and exemplary methods for drying the treated atomized powder at 110 are also described in more detail below.

[0026] The dried, atomized powder, referred to herein as the finished atomized powder, may then be packaged at 112 or otherwise conditioned for use.

[0027] Briefly, as shown by the dashed line in FIG. 1, a step of sieving the raw metal powder at 106 is provided in the exemplary embodiment of the process 100 described above prior to removing ultrafine particles 206 (see FIG. 2) at 108, although in other embodiments the process 100 of FIG. 1 may additionally or alternatively include a sieving step at 106′ after removing ultrafine particles 206 at 108.

[0028] Referring now to FIG. 3, an ultrafine particle removal system 300 according to an exemplary embodiment of the present disclosure is shown generally.

[0029] The exemplary ultrafine particle removal system 300 includes a container 302 defining a mixing cavity 304 for receiving an atomized powder 306. In particular, in the illustrated embodiment, the container 302 includes a door 308 that is rotatable about a hinge 310 (indicated by arrow 312) between a closed position (shown) and an open position (shown in dashed lines). When the door 308 is in the open position, the atomized 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 may form a fluid-tight seal with the remainder of the container 302.

[0030] The atomized powder 306 may be generated during a process for processing metal into a finished metal powder, such as the exemplary process 100 of Figure 1. Accordingly, the atomized powder 306 may be provided to the mixing cavity 304 of the container 302 after a sieving step 314 to obtain the atomized powder 306 defining a particle size distribution.

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

[0032] It will be appreciated that the ultra-fine particulate filter 316 may have any suitable configuration. In at least certain exemplary embodiments, the ultra-fine particulate filter 316 may be a metal porous filter. Such a metal porous filter has a nominal opening larger than the low cut size of the powder and may preferentially filter more ultra-fine particles depending on the pressure differential and thickness of the powder cake.

[0033] As mentioned above, the attractive forces between the ultrafine particles and the fine particles of the atomized powder 306 may be strong enough to resist mechanical sieving processes. Therefore, the ultrafine particle removal system 300 of FIG. 3 further includes a fluid nozzle 322 in fluid communication with the mixing cavity 304 to provide a removal liquid 324 (see FIG. 4, described below) to the mixing cavity 304. As 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 so as to maintain the original purity of the powder.

[0034] The vessel 302 further defines an outlet 326 at a location downstream of the ultraparticulate filter 316 from the fluid nozzle 322, and the ultraparticulate removal system 300 further includes a recirculation assembly 328 having a recirculation loop 330 (e.g., formed of one or more conduits) fluidly coupled to the outlet 326 and thus to the mixing cavity 304 at a location downstream of the ultraparticulate 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, in the illustrated embodiment, recirculation assembly 328 further includes a pump 332 that creates a pressure differential to drive fluid flow through recirculation loop 330 of recirculation assembly 328, and a particulate filter 334. Particulate filter 334 may be configured to filter out particles smaller than 1 μm, for example, as described in more detail below.

[0036] 4, the exemplary ultrafine particle removal system 300 of FIG. 3 is depicted during operation. In particular, during operation, the ultrafine particle removal system 300 is configured to contact the atomized powder 306 (see FIG. 3) received in the mixing cavity 304 of the container 302 with the removal liquid 324 to form a mixture 336 of the atomized powder 306 (see FIG. 3) and the removal liquid 324. In the illustrated embodiment, the ultrafine particle removal system 300 is further configured to apply energy to the mixture 336. As described above, the atomized powder 306 includes fine particles and ultrafine particles (see particles 202, 206 of FIG. 2), and applying energy to the mixture 336 facilitates separating the ultrafine particles from the fine particles in the mixture 336.

[0037] In the embodiment of FIG. 4, applying energy to the mixture 336 may include, for example, spraying the removal liquid 324 onto the atomized powder 306 using a fluid nozzle 322 at a pressure greater than ambient pressure (e.g., between 5 pounds per square inch (psi) and 250 psi, e.g., between 10 psi and 100 psi).

[0038] Moreover, in the illustrated embodiment, applying energy to the mixture 336 further includes exposing the mixture 336 to ultrasonic energy. In particular, in the illustrated embodiment, the ultrafine particle removal system 300 further includes an ultrasonic probe 338 extending into the mixing cavity 304 at a location to interact with the mixture 336. The ultrasonic probe 338 is operably connected to a power source 340 such that, in response to a command, the ultrasonic probe 338 can be provided with sufficient power to provide 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 atomized powder 306 (see FIG. 3) and the removal liquid 324 in any other suitable manner. For example, with brief reference to FIG. 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 FIG. 5 may be configured in substantially the same manner as the ultrafine particle removal system 300 of FIG. 4, and the same or similar numbers may refer to the same or similar parts. However, in the embodiment of FIG. 5, instead of the ultrasonic probe 338, the ultrafine particle removal system 300 includes a mixer 342 disposed within the mixing cavity 304 to add energy to the mixture 336 of the atomized powder 306 (see FIG. 3) and the removal liquid 324. The mixer 342 includes one or more paddles 344, more specifically, a plurality of paddles 344 attached to a shaft 346 configured to rotate about the axis of the shaft 346 to add energy to the mixture 336. The plurality of paddles 346 generate a centrifugal force, which may also be generated by a swirling flow of the liquid. The ultrafine particle removal system 300 of FIG. 5 further includes a power supply 348 operably coupled to the mixer 342 to provide power to the mixer 342.

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

[0041] It will be understood that the liquid classification system 370 shown in Figure 6 is provided by way of example only, and in other exemplary embodiments, other suitable liquid classification systems may be utilized in the ultrafine particle removal system 300 of the present disclosure.

[0042] 4, it should be understood that by contacting the atomized powder 306 (see FIG. 3) 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, 206 in FIG. 2). In particular, the removal liquid 324 can define an electrical permittivity that shields the electrical interactions (e.g., dipole-dipole interactions) between the ultrafine particles and the fine particles, such that the ultrafine particles can be more easily detached by the addition of energy to the mixture 336. It should be further understood that the addition of energy to the mixture 336 of the atomized powder 306 and the removal liquid 324 can facilitate the removal of the ultrafine particles from the fine particles of the atomized powder 306, such that 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 and separate the ultrafine particles from the fine particles after applying energy to the mixture 336. As shown in dashed lines in FIG. 4 and shown in more detail generally in callout circle B of FIG. 4, the vessel 302 further includes a blocker layer 350 that selectively fluidly isolates the ultrafine particle filter 316 from the mixing cavity 304. In the illustrated exemplary embodiment, the blocker layer 350 includes a wall 352 that defines a plurality of openings 354 and a respective plurality of flapper valve doors 356 disposed within each of the plurality of openings 354. Each flapper valve door 356 may be pivotable between an open position (shown in dashed lines) that allows fluid flow through the opening 354 and a closed position that prevents fluid flow through the opening 354.

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

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

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

[0047] After the removal solution 324 and ultrafine particles are separated from the fine particles, the fine particles can be removed (e.g., through door 308 of container 302) and dried using a drying device 362. Drying device 362 can be a vacuum drying device that exposes the fine particles from ultrafine particle removal system 300 to a vacuum environment (pressure less than atmospheric pressure) and controls the atmosphere, temperature, etc. to which the fine particles are exposed. A thermal oven 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 FIG. 3 ) given the size of the ultrafine particles. For example, the fine particles may be referred to as finished metal powder after being dried using the drying device 362, and the finished metal powder mass M Finish The atomized powder 306 provided to the ultrafine particle removal system 300 (see FIG. 3) has an initial mass M Initial The final metal powder mass M may be defined as Finish , initial mass M Initial may be 0.90 or greater, such as 0.95 or greater. Thus, the process of removing ultra-fine 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 equipment, the finished metal powder mass M Finish is substantially lower (e.g., the finished metal powder mass M Finish , initial mass M Initial It will be appreciated that the ratio of 0.85 to 0.8 (for example, 0.8) is affected by two processes during insertion into the cavity and drying.

[0050] As briefly discussed above, the removal liquid 324 may be water or an organic or inorganic solvent. Additionally or alternatively, if the reactive metal powder is a reactive metal powder that is not prone to reacting with water, the removal liquid 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 liquid 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 the reactive metal powder. Halocarbon liquids also generally have relatively low boiling points so that they can evaporate relatively quickly from the reactive metal powder after processing. Fluorocarbon liquids according to various aspects of the present invention include, for example, Novec TM , hydrofluorocarbons, fluorinated ketones, etc.

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

[0053] The method includes (a) contacting an atomized powder with a removal liquid to form a mixture of the atomized powder and the removal liquid. The atomized powder includes fine particles and ultrafine particles. In at least certain exemplary embodiments, the atomized powder may be free of dopants and / or flow enhancers or attachment molecules that reduce the hydrophilicity of the particles. Such hydrophilicity-reducing binding molecules are described, for example, in Canadian Patent Application CA3138388. The atomized powder of the present disclosure does not include intentional elemental additions as referred to by ASTM F 1580-18 or composition doping as referred to by AMS 7002A.

[0054] The method further includes (b) applying energy to the mixture of the atomized powder and the removal liquid to separate the ultrafine particles from the fine particles.

[0055] In certain exemplary embodiments, applying energy to the mixture of atomized 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, applying energy to the mixture of atomized powder and removal liquid in (b) includes atomizing pressurized removal liquid into the atomized powder.

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

[0057] The method may further comprise (d) classifying or sieving the raw atomized powder to obtain the atomized powder prior to contacting the atomized powder with the removal liquid.

[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 the separated ultrafine particles in a recirculation loop, (f) filtering the separated ultrafine particles from the removal liquid in the recirculation loop, and (g) returning the filtered removal liquid to the first batch of atomized powder or the second batch of atomized powder.

[0059] In the past, it was thought that exposing reactive metal powders to moisture was undesirable. This is because moisture is generally believed to increase the cohesive forces between fine particles, particularly between ultrafine particles and fine particles. Thus, in the past, the exposure of reactive metal powders to moisture would reduce the flowability of the resulting powder. However, the inventors of the present disclosure have unexpectedly discovered that by exposing the reactive metal powder to a sufficient amount of a removal liquid to form a mixture of the reactive metal powder and the removal liquid and adding energy to the mixture, ultrafine particles can actually be removed from the fine particles, and further, such removal of ultrafine particles can significantly improve the flowability of the reactive metal powder after drying.

[0060] In particular, the flowability of the powder (i.e., its fluidity, F RMP A common measure for the flowability, F, of the resulting powder is achieved by using the Hall test according to ASTM B213-20. The removal of ultrafine particles from the atomized powder according to the present invention is achieved by improving the flowability, F, of the resulting powder. RMP It has been found that the flowability F RMP Increased throughput can provide significant benefits, for example, in the additive manufacturing industry, as well as in other industries.

[0061] The inventors have determined that the size of the particles of the finished metal powder is S RMP (and size S RMP Each particle has an average mass M C ) and the apparent density of the finished metal powder, D RMP Both of these are related to the volume flowability of the finished metal powder. VRMP For example, larger particulates generally have improved volume flow properties F compared to smaller powders with similar properties. VRMP Similarly, denser finished metal powders generally have improved flow properties F compared to less dense finished metal powders having similar properties. RMP Also has.

[0062] For example, to function in a desired manner in an additive manufacturing machine, the inventors need to determine a minimum volumetric flowability F VRMP It was found that these volume flow rates F VRMP can be achieved using the improvements associated with the processes and methods described herein. Finished metal powders exhibiting flow properties below these thresholds may not be able to function in the desired manner, e.g., may clog or slow down production using the powder. The inventors have discovered that the volume flow properties F of alloys that have been found to provide the above benefits. VRMP , the size of the particles in the finished metal powder S RMP , apparent density D RMP , the average mass of each particle M C , Size S RMP , bulk density D BULK The relationship is as follows:

[0063] F VRMP ≧0.3×ln(M C )+2

[0064] M C Size S RMP The average mass of the particles is between 0.001 micrograms and 1 microgram. C is obtained by calculating the mass of a sphere of radius equal to half the size of the SRMP, and the density is the bulk density D of the alloy. BULK In particular, M C is found using the following relationship:

[0065]

number

[0066] S RMP is the D10 value (defined as the point under which 10% of the particles lie on the particle size distribution curve measured according to ASTM B822-20) and is between 5 and 30 micrometers. The instrument used to carry out the measurement method is a Beckman Coulter LS 13 320. D BULK is the bulk density of the alloy, which can be obtained according to ASTM B923-22. BULK is 1.5~20g / cm 3 There are various instruments that can be used for particle size determination by laser diffraction according to ASTM B822-20. These include the Beckman Coulter TM LS 13 320, Cilas 990L TM , Malvern TM , Mastersizer TM , Sympatec TM , HELOS TM , Microtrac TM Particle size analyzer S3500 TMand the like. As will be appreciated, there may be inherent variability in the D10 values ​​obtained from a particular powder tested using available equipment under the guidelines of ASTM B822-20. For purposes of this disclosure, the ranges of D10 values ​​provided herein are intended to refer to powders that exhibit D10 values ​​within the disclosed and / or claimed ranges when tested using at least one of the approved methods and equipment in accordance with ASTM B822-20.

[0067] F VRMP is the volumetric flow rate, which is between 0.1 cubic centimeters per second and 1.4 cubic centimeters per second. VRMP is the time required for a powder to flow through a funnel (F) using 50 grams of powder in a Hall Flow test (per ASTM B213-20). HFT The volumetric flow rate F is obtained by dividing the apparent density by the mass fraction (expressed in grams per cubic centimeter) and is given in grams per cubic centimeter according to ASTM B212-21. VRMP The final unit of is cubic centimeters divided by seconds. D measured according to ASTM B212-21 RMP is between 0.8 grams / cubic centimeter and 11 grams / cubic centimeter. In particular, F VRMP is found using the following relationship:

[0068]

number

[0069] 7 and 8, various exemplary powders according to one or more exemplary embodiments of the present disclosure are shown. In particular, FIG. 7 provides a table with numerical values ​​corresponding to some of the exemplary powders of FIG. 8. FIG. 8 is a graph 400 of powders according to one or more exemplary embodiments of the present invention, showing volume flowability F on the Y-axis 402. VRMP and the particle size S on the X-axis 404 RMP The average mass M C This indicates that:

[0070] As shown, plot 400 of FIG. 8 shows the flowability F VRMP is 0.3×ln(M C )+2(line 408) or more and 0.3ln(M C )+2.4 (line 410).

[0071] In the exemplary embodiment shown in FIG. 8, the powder has a volume flowability F of 0.35 to 1.05. VRMP Titanium alloys (such as Ti-6Al-4V) with volume fluidity F of 0.7 to 1.1 VRMP Nickel or nickel alloys with a volume flow rate F of 1.0 to 1.2 VRMP Niobium or niobium alloy having a volume fluidity F of 0.2 to 0.5; VRMP The alloy may be aluminum or an aluminum alloy having the above formula:

[0072] Referring now to FIG. 9, a table of four example reactive metal powders illustrating the advantages of the process of the present disclosure is shown.

[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 through a 15 micrometer mesh. As can be seen, the ultrafine particle removal process confirmed a slight increase in D10 (increase rate of more than 0%, less than 10%, e.g., less than 5%), a slight decrease in the percentage of particles below 10 microns, and a significant increase in flowability (improvement of 10% to 100%, e.g., improvement of 25% to 50%).

[0074] Example 2. A second lot of nickel alloy was processed in the same manner as the first lot, except specifically, the ultrafine particle removal process resulted in a slight increase in D10 (>0% increase, <10%), a slight decrease in the percentage of particles below 10 microns, and a significant increase in flowability (between 10% improvement and 100% improvement).

[0075] Example 3. A third lot of niobium alloy was processed in the same manner as the first lot (but with 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 (>0% increase, <10%, e.g., <5%), no measurable change in the percentage of particles below 10 microns, and a significant increase in flowability (between 10% improvement and 100% improvement).

[0076] Example 4. The fourth batch of aluminum alloy also 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 included spraying the atomized powder with fluorocarbon liquid and filtering through a 20 micron mesh. Thus, it will be understood that the mixture of atomized powder and removal liquid (fluorocarbon liquid in Example 4) was filtered through a mesh size smaller than the lower limit of the particle size distribution of the atomized powder being tested. As can be seen, the ultrafine particle removal process slightly increased D10 (increase of 0% or more and increase of less than 20%), reduced the percentage of particles below 10 microns, and significantly increased flowability (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 appreciated that the D10 value is not substantially affected by the ultra-fine powder removal process.

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

[0079] A method for removing ultrafine particles from an atomized powder, the method comprising: contacting the atomized powder with a removal liquid, the atomized powder comprising fine particles and ultrafine particles; and contacting the atomized powder with the removal liquid comprising adding energy to a mixture of the atomized powder and the removal liquid so as to separate the ultrafine particles from the fine particles, thereby separating the removal liquid and the ultrafine particles from the fine particles.

[0080] Any of the above-mentioned methods, wherein the atomized powder has a particle size distribution of 0 micrometers to 150 micrometers.

[0081] Any of the preceding methods, wherein the atomized powder is a reactive metal powder.

[0082] Any of the preceding methods, wherein the reactive metal powder comprises 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] Any of the preceding methods, wherein the removal liquid is a halocarbon liquid.

[0085] Any of the preceding methods, further comprising sieving untreated metal powder to obtain said atomized powder prior to contacting said atomized powder with said removal liquid.

[0086] Any of the preceding methods, wherein sieving the untreated atomized powder comprises dry sieving the untreated metal powder or wet sieving the untreated metal powder.

[0087] Any of the preceding methods, wherein adding energy to the mixture of atomized powder and removal liquid includes exposing the mixture to ultrasonic energy, mechanically agitating the mixture, adding kinetic energy from a fluid flow, or a combination thereof.

[0088] Any of the preceding methods, wherein applying energy to the mixture of the atomized powder and the removal liquid comprises spraying the removal liquid onto the atomized powder.

[0089] Any of the preceding methods, wherein the removal liquid is water, an organic or inorganic solvent, a halocarbon liquid, a fluorocarbon liquid, or a combination thereof.

[0090] The fine particles have a final mass M Finish and forming a finished metal powder defining an initial mass M prior to contacting the atomized powder with the removal liquid. Initial Define M Finish and M. Initial Any of the preceding methods, wherein the ratio of

[0091] Any of the above methods, wherein the atomized powder is a first batch atomized powder, the method further comprising 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 atomized powder or to a second batch atomized powder.

[0092] Any of the preceding methods, wherein applying energy to the mixture of atomized powder and the removal liquid comprises exposing the mixture to ultrasonic energy.

[0093] Any of the preceding methods, wherein applying energy to the mixture of the atomized powder and the removal liquid comprises mechanically agitating the mixture.

[0094] Any of the preceding methods, wherein adding energy to the mixture of atomized powder and the removal liquid comprises adding kinetic energy from a fluid flow.

[0095] 1. An ultrafine particle removal system comprising: a container defining a mixing cavity for receiving an atomized powder, the container further comprising an ultrafine particle filter exposed to the mixing cavity; a fluid nozzle in fluid communication with the mixing cavity for providing a removal liquid to the mixing cavity; and a recirculation assembly fluidly coupled to the mixing cavity at a location downstream of the ultrafine particle filter and further fluidly coupled to the fluid nozzle, the recirculation assembly including a fine filter for removing ultrafine particles from a mixture received from the mixing cavity.

[0096] Any of the ultrafine particle removal systems described above, wherein the atomized powder has a particle size distribution of 0 micrometers to 150 micrometers.

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

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

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

[0100] Any of the preceding ultrafine particle removal systems, wherein the ultrafine particle filter defines a plurality of openings defining a diameter of between 5 μm and 10 μm.

[0101] Any of the preceding ultrafine particle removal systems, wherein the container further includes a blocker layer selectively fluidly isolating the ultrafine particle filter from the mixing cavity, the blocker layer including a wall defining a plurality of openings and a plurality of flapper valve doors disposed in each of the plurality of openings, respectively.

[0102] 1. An atomized powder mixture comprising a reactive metal powder comprising a fine powder formed from a reactive metal, the reactive metal powder having a volume flowability F measured according to ASTM B213-20. VRMP (cubic centimeters per second) and bulk density D BULK(grams per cubic centimeter), and the particles of the reactive metal powder have a size S corresponding to the D10 value of the reactive metal powder measured in accordance with ASTM B822-20. RMP (micrometers) and average mass M C (micrograms) and volumetric fluidity F VRMP is 0.3×ln(M C )+2 or more, and M C but

[0103]

number

[0104] The reactive metal powder is treated to remove ultra-fine metal powder from the fine powder, such that RMP is 5 micrometers to 30 micrometers, F VRMP is 0.1 cubic centimeters / second to 1.4 cubic centimeters / second, and D BULK Atomization powder mixture with a density of 1.5 grams / cubic centimeter to 20 grams / cubic centimeter.

[0105] Any of the preceding atomized powder mixtures, wherein the reactive metal powder comprises titanium, titanium alloys, zirconium, zirconium alloys, magnesium, magnesium alloys, aluminum, aluminum alloys, nickel, nickel alloys, niobium, niobium alloys, or combinations thereof.

[0106] Any of the preceding atomized powder mixtures, wherein the reactive metal powder defines a particle size distribution from 0 micrometers to 150 micrometers.

[0107] Said F VRMP But, 0.3×ln(M C )+2.4 or less.

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

[0109] The reactive metal powder is subjected to Hall Flow Test Flowability F HFT The volume flow rate F VRMP but

[0110]

number

[0111] Any of the preceding atomized powder mixtures,

[0112] An atomized powder mixture formed using any of the above methods.

[0113] An atomized powder mixture formed using any of the ultrafine particle removal systems described above.

[0114] This specification uses examples to disclose the disclosure, including the best mode, and also enables any person skilled in the art to practice the disclosure, including making and using any device or system, and practicing any incorporated methods. The patentable scope of the disclosure is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they contain structural elements that do not differ from the literal language of the claims, or if they contain equivalent structural elements that do not differ substantially from the literal language of the claims.

Claims

1. A method for removing ultrafine particles (206) from an atomized powder (306), comprising the steps of: contacting the atomized powder (306) with a removal liquid (324); The atomized powder (306) includes fine particles (202) and ultrafine particles (206), Contacting the atomized powder (306) with the removal liquid (324) comprises: applying energy to the mixture (336) of the atomized powder (306) and the removal liquid (324) to separate the ultrafine particles (206) from the fine particles (202); Separating the removal solution (324) and the ultrafine particles (206) from the fine particles (202); Ultrafine particle removal method.

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

3. The method of claim 1 , wherein the atomized powder (306) is a reactive metal powder.

4. The reactive metal powder comprises titanium, a titanium alloy, zirconium, a zirconium alloy, magnesium, a magnesium alloy, aluminum, an aluminum alloy, nickel, a nickel alloy, niobium, a niobium alloy, or a combination thereof; The method for removing ultrafine particles according to claim 3.

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

6. the method further comprising sieving the untreated metal powder to obtain the atomized powder (306) prior to contacting the atomized powder (306) with the removal liquid (324). The method for removing ultrafine particles according to claim 1 .

7. sieving the green metal powder comprises dry sieving the green metal powder or wet sieving the green metal powder. The method for removing ultrafine particles according to claim 6.

8. 2. The method of claim 1, wherein applying energy to the mixture (336) of the atomized powder (306) and the removal liquid (324) comprises exposing the mixture (336) to ultrasonic energy, mechanically agitating the mixture (336), applying kinetic energy from a fluid flow, or a combination thereof.

9. 2. The method of claim 1, wherein the removal liquid (324) is water, an organic or inorganic solvent, a halocarbon liquid, a fluorocarbon liquid, or a combination thereof.

10. The fine particles (202) have a final mass M Ｆｉｎｉｓｈ forming a finished metal powder defining The atomized powder (306) has an initial mass M before the atomized powder (306) contacts the removal liquid (324). Ｉｎｉｔｉａｌ Define M Ｉｎｉｔｉａｌ M Ｆｉｎｉｓｈ The ratio of is more than 0.

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

11. the atomized powder (306) is a first batch atomized powder (306); The method for removing ultrafine particles comprises: receiving the separated removal solution (324) and ultrafine particles (206) in a recirculation loop; filtering the ultrafine particles (206) from the removal solution (324) in the recirculation loop; providing the filtered removal liquid (324) to the first batch of atomized powder (306) or to the second batch of atomized powder (306); [0023] The method for removing ultrafine particles according to claim 1 .

12. A mixture (336) of atomized powder (306), a reactive metal powder comprising a fine powder formed from a reactive metal; The reactive metal powder is Volume flowability F measured according to ASTM B213-20 ＶＲＭＰ (cubic centimeters per second) and Bulk density D ＢＵＬＫ (grams per cubic centimeter) The reactive metal powder particles (202, 204) Size S corresponding to the D10 value of the reactive metal powder measured according to ASTM B822-20 ＲＭＰ (micrometers) and Average mass M Ｃ (micrograms) is specified, Volumetric fluidity F ＶＲＭＰ is 0.3 × ln (M Ｃ the reactive metal powder is treated to remove ultrafine metal powder from the fine powder such that the R 1 / R 2 ratio is greater than or equal to 1 / R 2 +2; Preface Average mass M Ｃ が [0010] and S ＲＭＰ is between 5 micrometers and 30 micrometers, F ＶＲＭＰ is between 0.1 cubic centimeters per second and 1.4 cubic centimeters per second; D ＢＵＬＫ is between 1.5 grams / cubic centimeter and 20 grams / cubic centimeter; Atomized powder mixture.

13. 13. The mixture of atomized powders of claim 12, wherein the reactive metal powder comprises titanium, titanium alloys, zirconium, zirconium alloys, magnesium, magnesium alloys, aluminum, aluminum alloys, nickel, nickel alloys, niobium, niobium alloys, or combinations thereof.

14. 14. The atomized powder mixture of claim 13, wherein the reactive metal powder defines a particle size distribution from 0 micrometers to 106 micrometers.

15. Said F ＶＲＭＰ is 0.3 × ln (M Ｃ 14. The mixture of atomized powders according to claim 13, wherein the MnO2 content is 0.01 or less than 0.01.

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