System and method for atomized powder processing and processed powder

Abstract

A method of removing ultrafine particles from an atomized powder is provided. The method includes contacting an atomized powder with a removal liquid, the atomized powder including fine particles and ultrafine particles, where contacting the atomized powder with the removal liquid includes increasing energy to a mixture of the atomized powder and the removal liquid to disengage the ultrafine particles from the fine particles; and separating the removal liquid and the ultrafine particles from the fine particles.

Description

Technical Field

[0001] The present invention relates to a system and method for processing atomized powder, and powder processed according to the system and method. Background Art

[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 can be used in 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

[0003] In one aspect, the present invention relates to a method for removing ultrafine particles from an atomized powder, the method comprising:

[0004] contacting an atomized powder with a removal liquid to form a mixture of the atomized powder and the removal liquid, the atomized powder comprising fine particles and ultrafine particles;

[0005] Adding energy to the atomized powder and removal liquid mixture to separate ultrafine particles from fine particles; and

[0006] The liquid is removed and the detached ultrafine particles are separated from the fine particles.

[0007] In another aspect, the present invention also relates to an ultrafine particle removal system, comprising:

[0008] a container having a mixing chamber for receiving the aerosolized powder, the container further comprising an ultrafine particle filter exposed to the mixing chamber;

[0009] a fluid nozzle in fluid communication with the mixing chamber for providing a removal liquid to the mixing chamber; and

[0010] A recirculation assembly is fluidly connected to the mixing chamber at a location downstream of the ultrafine particle filter and is also fluidly connected to the fluid nozzle, the recirculation assembly including a particulate filter for removing ultrafine particles from the mixture received from the mixing chamber.

[0011] In another aspect, the present invention also relates to an atomized powder mixture comprising:

[0012] A reactive metal powder comprising a fine powder formed of a reactive metal,

[0013] The reactive metal powder has a volume flowability F in cubic centimeters per second measured according to ASTM B213-20. VRMP and the bulk density D in grams per cubic centimeter bulk ;

[0014] The particles of the reactive metal powder have a size S in micrometers. RMP and the average mass M in micrograms C , the size S RMP Corresponds to the D10 value of the active metal powder measured according to ASTM B822-20;

[0015] wherein the reactive metal powder has been processed to remove ultrafine metal powder from the fine powder so that the bulk flowability F VRMP Greater than or equal to 0.3×ln(M C )+2, and

[0016] The average mass M C equal

[0017]

[0018] Where S RMP Between 5 μm and 30 μm, F VRMP Between 0.1 cubic centimeters per second and 1.4 cubic centimeters per second, D BULK Between 1.5 and 20 grams per cubic centimeter. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] A full and enabling disclosure of the present invention, including the best mode thereof, to one of ordinary skill in the art is set forth in the specification with reference to the accompanying drawings, in which:

[0020] Figure 1 is a schematic flow chart of a method according to an exemplary aspect of the invention.

[0021] Figure 2 is an enlarged view of an aerosolized powder sample according to an exemplary aspect of the present invention.

[0022] Figure 3 An ultrafine particle removal system according to an exemplary aspect of the present invention.

[0023] Figure 4 A system for removing ultrafine particles according to another exemplary aspect of the present invention is provided.

[0024] Figure 5 A system for removing ultrafine particles according to another exemplary aspect of the present invention is provided.

[0025] Figure 6 is a liquid classifier system that can be incorporated into the ultrafine particle removal system of the present invention.

[0026] Figure 7 To include Figure 8 Table of values ​​corresponding to several exemplary powders.

[0027] Figure 8 is a powder diagram according to one or more exemplary embodiments of the present invention.

[0028] Fig. 9 Examples of four reactive metal powders are shown, illustrating the benefits of the method of the present invention. DETAILED DESCRIPTION

[0029] Reference will now be made in detail to embodiments of the present invention, one or more examples of which are shown in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. The same or similar designations in the drawings and the specification are used to refer to the same or similar parts in the present disclosure.

[0030] The word "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations. Furthermore, unless otherwise noted, all implementations described herein should be considered exemplary.

[0031] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0032] In a context such as “at least one of A, B, and C,” the term “at least one of” means only A, only B, only C, or any combination of A, B, and C.

[0033] The phrases "from X to Y" and "between X and Y" both refer to numerical ranges that include the endpoints (ie, refer to numerical ranges that include X and Y).

[0034] The expression "particle size distribution" refers to a powder wherein at least 80% of the resulting powder has a particle size distribution between a lower limit and an upper limit. This value is 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.

[0035] The expression "reactive metal powder" used herein refers to a metal powder formed of an oxygen-reactive metal, a nitrogen-reactive metal, or both. For example, the reactive metal powder may include at least one 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.

[0036] The term "raw metal powder" as used herein refers to metal powder obtained directly from the atomization process without any post-processing steps such as screening or classification techniques.

[0037] Referring now to the drawings, wherein like numerals represent like elements throughout the several views, Figure 1 Flowchart of a method 100 for processing a metal into a finished metal powder. More specifically, for the illustrated embodiment, the method 100 is used to process a reactive metal into a finished reactive metal powder.

[0038] The method 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 rod, a metal powder, or the like.

[0039] Atomizing the metal at 104 may include utilizing any suitable atomization method. For example, in at least one exemplary embodiment, atomizing the metal at 104 may include atomizing the metal using a plasma atomization method. In particular, in at least one exemplary embodiment of the present disclosure, atomizing the metal at 104 may include utilizing one or more exemplary plasma atomization methods discussed in U.S. Patent No. 11,198,179, published on December 14, 2021, and / or U.S. Patent Application No. 2019 / 0001416, published on January 3, 2019. Each of the foregoing is incorporated herein by reference in its entirety and for all purposes.

[0040] Thus, it should be appreciated that in at least one exemplary embodiment of the present invention, 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 the preheated metal into a fine powder. An additive gas may be added to improve the flowability of the resulting powder.

[0041] In other exemplary embodiments, other suitable atomization methods may be utilized, such as other suitable plasma atomization methods, gas atomization methods, shell melting gas atomization methods, electrode induction melting gas atomization methods (EIGA methods), plasma rotating electrode methods, etc. In addition, it should be understood that, as used herein, atomizing 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 discussed in U.S. Patent No. 11,235,385 issued on February 1, 2022, which is fully incorporated herein by reference and for all purposes.

[0042] Atomizing the metal at 104 may produce raw metal powder. Still referring to Figure 1, the method 100 also includes screening the raw metal powder at 106 to obtain an atomized powder having a particle size distribution. Screening the raw metal powder at 106 may include dry screening or applying gas classification to the raw metal powder, wet screening the raw metal powder, or a combination thereof. Dry screening the raw metal powder may include passing the raw metal powder through one or more screens or filters while, for example, applying vibration to the raw metal powder, the screens or filters, or both.

[0043] As described above, the atomized powder obtained by sieving at 106 can define a particle size distribution. In particular, the atomized powder obtained by sieving at 106 can have a particle size distribution of 0 μm to 150 μm. It should be understood that as used herein, and in the context of sieving at 106, the term "particle size distribution" has the definition provided above. The atomized powder can be obtained by passing the raw metal powder through a first screen or filter, which is designed to remove particles greater than the upper limit of the particle size distribution (also referred to as the upper limit particle size (upper cut-size)) (e.g., 150 μm in the above embodiment), and then optionally subjecting the raw metal powder to a second filtering or classification step, which is designed to remove particles less than the lower limit of the particle size distribution (e.g., 10 μm in some embodiments). This lower limit is also referred to as the lower limit particle size (lower cut-size).

[0044] It should be understood that in other exemplary embodiments of the present invention, the atomized powder obtained by sieving at 106 may have a particle size distribution in which the lower limit is between 0 μm and 75 μm, such as between 5 μm and 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. In addition, the atomized powder obtained by sieving at 106 may have a particle size distribution in which the upper limit range is between 20 μm and 150 μm, such as between 45 μm and 75 μm, such as 40 μm, 53 μm, 65 μm, 75 μm, 85 μm, 95 μm, 105 μm or 115 μm.

[0045] It will be further understood from the description herein that, despite the screening at 106, the atomized powder may also include ultrafine particles or satellite particles attached to fine particles having a particle size within the particle size distribution range. For example, now briefly referring to Figure 2, provides an enlarged view of a sample 200 of an atomized powder according to an exemplary aspect of the present disclosure. The atomized powder includes fine particles 202, and the fine particles 202 have a size within a particle size distribution. It is noteworthy that, as used herein, the term "size" with respect to a particle refers to a maximum transverse measurement value 204. For example, when the particle is a perfect sphere, the maximum transverse measurement value 204 is the diameter of the sphere. The atomized powder also includes ultrafine particles 206 combined with the fine particles 202. In at least some exemplary aspects, the ultrafine particles 206 may have a size less than the particle size distribution (i.e., a size less than the lower limit of the particle size distribution). For example, in at least some exemplary embodiments, the ultrafine particles 206 may have a size less than or equal to 7 μm, for example less than or equal to 5 μm.

[0046] It should 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 some exemplary embodiments, a dipole-dipole or complex electrical interaction between one or more ultrafine particles 206 and one or more 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 Figure 1 106).

[0047] The presence of ultrafine particles 206 adhering to fine particles 202 in the generated atomized powder may reduce the flowability of the atomized powder due to, for example, increased roughness of the fine particles and various electromagnetic interactions.

[0048] Reference again Figure 1 In order to increase the flowability of the atomized powder, the method 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 to which the atomized powder is subjected at 108 will be described below with reference to, for example, Figures 3 to 5 For example, as will be 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 a removal liquid. Figure 1 The method 100 also includes drying the processed atomized powder at 110. Additional details and exemplary methods of drying the processed atomized powder at 110 are described in detail below.

[0049] The dried, processed aerosolized powder, referred to herein as finished aerosolized powder, may be packaged or otherwise prepared for use at 112 .

[0050] In short, Figure 1As shown by the dashed line in FIG. 1 , although in the exemplary aspect of the above method 100, the step of screening the raw metal powder at 106 is to remove the ultrafine particles 206 at 108 (see FIG. 1 ). Figure 2 ), but in other embodiments, Figure 1 The method 100 may additionally or alternatively include a screening step 106 ′ after removing the ultrafine particles 206 at 108 .

[0051] Reference Figure 3 , schematically depicts an ultrafine particle removal system 300 according to an exemplary aspect of the present invention.

[0052] The exemplary ultrafine particle removal system 300 includes a container 302 having a mixing chamber 304 for receiving an atomized powder 306. In particular, for the illustrated embodiment, the container 302 includes a door 308 that can rotate between a closed position (shown) and an open position (shown in phantom) about a hinge 310 (as indicated by arrow 312). When the door 308 is in the open position, the atomized powder 306 can be added to the mixing chamber 304, or removed from the mixing chamber 304. When the door 308 is in the closed position, the door 308 can form a fluid-tight seal with the rest of the container 302.

[0053] Atomized powder 306 may be produced during the execution of a method for processing metal into finished metal powder, e.g. Figure 1 1. Thus, after the sieving step 314, the atomized powder 306 can be provided to the mixing chamber 304 of the container 302 to produce an atomized powder 306 having a defined particle size distribution.

[0054] Figure 3 The container 302 of the ultrafine particle removal system 300 also includes an ultrafine particle filter 316 exposed to the mixing chamber 304. More specifically, for the illustrated embodiment, the mixing chamber 304 is located above the ultrafine particle filter 316 along the vertical direction V defined by the ultrafine particle removal system 300. It is understood that the atomized powder includes fine particles with a size within the particle size distribution and ultrafine particles with a size that may be smaller than the particle size distribution (see Figure 2 As shown by the circle labeled A, the ultrafine particle filter 316 has a plurality of openings 318 having a diameter 320 small enough to prevent particles larger than the ultrafine particles of the atomized powder 306 from passing therethrough. For example, in at least some exemplary aspects, the diameter 320 of the openings 318 can be between 5 μm and 10 μm.

[0055] It should be understood that the ultrafine particle filter 316 can have any suitable configuration. In at least some exemplary embodiments, the ultrafine particle filter 316 can be a metal porous filter. Such a metal porous filter can have a nominal opening that is larger than the lower limit size of the powder and still preferentially filter out ultrafine particles, depending on the pressure difference and the thickness of the powder filter cake.

[0056] As described above, the attraction between the ultrafine particles and the fine particles of the atomized powder 306 may be strong enough to resist the mechanical sieving process. Figure 3 The ultrafine particle removal system 300 further includes a fluid nozzle 322 in fluid communication with the mixing chamber 304 for providing a removal liquid 324 (see Figure 4 , discussed below). As will be explained in more detail below, the removal liquid 324 can be water, a fluorocarbon liquid, a halocarbon liquid, an organic or inorganic solvent, or a combination thereof. One criterion for selecting the liquid should be that it does not chemically react with the powder to maintain the original purity of the powder.

[0057] The container 302 also defines an outlet 326 at a location downstream of the ultrafine particle filter 316 of the fluid nozzle 322, and the ultrafine particle removal system 300 also includes a recirculation assembly 328 having a recirculation loop 330 (formed by, for example, one or more conduits) that is fluidly connected to the outlet 326 and, therefore, to the mixing chamber 304 at a location downstream of the ultrafine particle filter 316. The recirculation assembly 328 is further fluidly connected to the fluid nozzle 322 for recirculating the removal liquid 324 received therethrough.

[0058] It is noted that for the described embodiment, the recirculation assembly 328 also includes a pump 332 and a particulate filter 334, the pump 332 generating a pressure differential for driving the fluid through the recirculation loop 330 of the recirculation assembly 328. The particulate filter 334 may be configured to extract particles smaller than, for example, 1 μm, as will be explained in more detail below.

[0059] Reference Figure 4 , Figure 3 The exemplary ultrafine particle removal system 300 is shown in operation. In particular, during operation, the ultrafine particle removal system 300 is configured to atomize powder 306 (see FIG. 1 ) contained in a mixing chamber 304 of a container 302. Figure 3 ) contacts the removal liquid 324 to form atomized powder 306 (see Figure 3 ) and the removal liquid 324. For the illustrated embodiment, the ultrafine particle removal system 300 is also configured to add energy to the mixture 336. As described above, the atomized powder 306 includes fine particles and ultrafine particles (see Figure 2particles 202, 206), and adding energy to the mixture 336 helps to separate the ultrafine particles from the fine particles within the mixture 336.

[0060] exist Figure 4 In an embodiment, adding energy to the mixture 336 includes using a fluid nozzle 322 to spray the atomized powder 306 with a removal liquid 324, for example at a pressure greater than ambient pressure (e.g., 5 pounds per square inch (psi) to 250 psi, such as 10 psi to 100 psi).

[0061] Additionally, for the embodiment described, adding energy to the mixture 336 also includes exposing the mixture 336 to ultrasonic energy. In particular, for the embodiment shown, the ultrafine particle removal system 300 also includes an ultrasonic probe 338 that extends into the mixing chamber 304 at a location that interacts with the mixture 336. The ultrasonic probe 338 is operably connected to the power source 340 so 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.

[0062] However, it should be understood that in other exemplary embodiments, the atomized powder 306 (see Figure 3 ) and removing the mixture 336 of liquid 324 increases energy. For example, briefly referring to Figure 5 , an ultrafine particle removal system 300 according to another exemplary embodiment of the present disclosure is provided. Figure 5 The exemplary ultrafine particle removal system 300 may be configured with Figure 4 The ultrafine particle removal system 300 is configured in substantially the same manner, and the same or similar numbers may refer to the same or similar components. Figure 5 In an embodiment, instead of the ultrasonic probe 338, the ultrafine particle removal system 300 includes a mixer 342 located in the mixing chamber 304 for atomizing the powder 306 (see Figure 3 ) and remove the mixture 336 of the liquid 324 to add energy. The mixer 342 includes one or more blades 344, more specifically, a plurality of blades 344 mounted on a shaft 346 and configured to rotate about the axis of the shaft 346 to add energy to the mixture 336. The plurality of blades 346 generate centrifugal force, which may also be generated by the vortex of the liquid. Figure 5 The ultrafine particle removal system 300 also includes a power source 348 operably connected to the mixer 342 for providing power to the mixer 342 .

[0063] Additionally, or alternatively, in other exemplary embodiments, a liquid staging system may be used to add energy to the mixture 336. Referring now briefly to Figure 6, provides a schematic diagram of a liquid classifier system 370 that can be incorporated into the ultrafine particle removal system 300 of the present disclosure (e.g., incorporated into one or more of the ultrafine particle removal systems 300 described above). Figure 6 The liquid classifier system 370 utilizes centrifugal force, wherein the removal liquid 324 is introduced through the inlet 372 together with the atomized powder 306 having a certain speed, so that when the atomized powder 306 (see Figure 3 ) and the removed liquid 324 is provided into the cylindrical body 374 of the liquid classifier system 370, the mixture 336 swirls (see arrow 380) within the body 374. The first outlet 376 of the liquid classifier system 370 is located below the second outlet 378 of the liquid classifier system 370 along the vertical direction V, so that coarser particles can be received through the first outlet 376, and the mixture of ultrafine particles and the removed liquid can be received through the second outlet 378.

[0064] It should be understood that Figure 6 The illustrated liquid classifier system 370 is provided as an example only. In other exemplary embodiments, other suitable liquid classifier systems may be used in the ultrafine particle removal system 300 of the present disclosure.

[0065] Now return to reference Figure 4 It should be understood that the atomized powder 306 (see Figure 3 ) and the removal liquid 324 may allow the removal liquid 324 to shield the ultrafine particles and fine particles of the atomized powder 306 (see Figure 2 In particular, the removal liquid 324 can define a dielectric constant 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 disengaged as energy is added to the mixture 336. It should also be understood that adding energy to the mixture 336 of the atomized powder 306 and the removal liquid 324 can promote 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.

[0066] The ultrafine particle removal system 300 is further configured to separate the removal liquid 324 and the dislodged ultrafine particles from the fine particles after adding energy to the mixture 336. Figure 4 As shown by the dotted line in Figure 4302, the container 302 also includes a barrier 350 that selectively isolates the ultrafine particle filter 316 from the mixing chamber 304 fluid. In the exemplary embodiment shown, the barrier 350 includes a wall 352 having a plurality of openings 354, and a corresponding plurality of flapper valves 356 located within each of the plurality of openings 354. Each flapper valve 356 can be pivoted between an open position (shown in dashed lines) that allows fluid to flow through the opening 354 and a closed position that prevents fluid from flowing through the opening 354.

[0067] In this manner, it should be appreciated that the barrier layer 350 may allow the ultrafine particle removal system 300 to provide atomized powder 306 (see FIG. 1 ) prior to separating the removal liquid 324 and the dislodged ultrafine particles from the fine particles. Figure 3 ) and removing the mixture 336 of liquid 324 increases the required amount of energy.

[0068] exist Figure 4 In an embodiment of the present invention, separating the removal liquid 324 and the detached ultrafine particles from the fine particles may include allowing the removal liquid 324 and the detached ultrafine particles to flow through the ultrafine particle filter 316 of the container 302, as shown by arrow 358 (representing a mixture of the removal liquid 324 and the ultrafine particles), and reach the recirculation component 328 through the outlet 326. As described above, the recirculation component 328 includes a particulate filter 334, which 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 manner, it should be understood that the removal liquid 324 can be filtered to remove the detached ultrafine particles from the removal liquid 324 within the recirculation loop 330 of the recirculation component 328, and the filtered removal liquid 324 can then be provided to the same or a second batch of atomized powder (not shown). This can result in a reduction in waste during operation of the ultrafine particle removal system 300.

[0069] Briefly, the ultrafine particle removal system 300 also 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.

[0070] After the removal liquid 324 and the ultrafine particles are separated from the fine particles, the fine particles can be removed (e.g., through the door 308 of the container 302) and dried using a drying device 362. The drying device 362 can be a vacuum drying device configured to expose the fine particles from the ultrafine particle removal system 300 to a vacuum environment (defined as a pressure less than the ambient pressure) in order to control, for example, the atmosphere and temperature to which the fine particles are exposed. A heating furnace can also be used to dry the powder.

[0071] It should be appreciated that, given the size of the ultrafine particles, the removal of the ultrafine particles using the ultrafine particle removal system 300 may not result in a significant reduction in the mass of the atomized powder 306 (see Figure 3 For example, after having been dried using the drying device 362, the fine particles, which may be referred to as the finished metal powder, may define the finished metal powder mass M 成品 Before the ultrafine particles are removed, they are provided to the ultrafine particle removal system 300 (see Figure 3 ) of the atomized powder 306 can define an initial mass M 初始 Finished metal powder mass M 成品 With initial mass M 初始 The ratio may be greater than or equal to 0.90, such as greater than or equal to 0.95. Therefore, the process of removing ultrafine particles from the atomized powder 306 does not result in a significant reduction in the quality of the finished metal powder.

[0072] It is worth noting that it should be understood that if the ultrafine particle removal process described herein is used in conjunction with a wet screening process in the same apparatus, the finished metal powder mass M 成品 The quality of the finished metal powder M will be significantly reduced (for example, 成品 With initial mass M 初始 The ratio may be less than 0.85, for example less than 0.8), which is affected by two processes between its insertion into the cavity and drying.

[0073] As briefly described above, the removal liquid 324 may be water or an organic or inorganic solvent. Additionally or alternatively, when the reactive metal powder is a reactive metal powder that reacts poorly 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.

[0074] 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, so that they can evaporate relatively quickly from reactive metal powders after processing. Examples of fluorocarbon liquids according to various aspects of the present disclosure include Novec TM , hydrofluorocarbons, and fluorinated ketones.

[0075] In addition, the present invention also provides a method for removing ultrafine particles from atomized powder. The method may include as Figure 1 A portion of the method 100 may be related to Figures 3 to 5 The ultrafine particle removal system 300 may be used in conjunction with, or may be included as part of or used with, any other suitable method or system.

[0076] The method includes contacting an atomized powder with a removal liquid at (a) to form a mixture of the atomized powder and the removal liquid. The atomized powder includes fine particles and ultrafine particles. In at least some exemplary aspects, the atomized powder may not contain any dopants and / or fluidity enhancers or attached molecules that reduce the hydrophilicity of the particles. For example, such attached molecules that reduce hydrophilicity are described in Canadian patent application CA3138388. The atomized powder of the present invention does not include the intentional element additions mentioned in ASTM F1580-18 or the component doping mentioned in AMS 7002A.

[0077] The method also includes adding energy to the mixture of the atomized powder and the removal liquid at (b) to separate the ultrafine particles from the fine particles.

[0078] In certain exemplary aspects, adding energy to the mixture of atomized powder and removal liquid at (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 aspects, adding energy to the mixture of atomized powder and removal liquid at (b) includes spraying the atomized powder with pressurized removal liquid.

[0079] The method also includes separating the removal liquid and the detached ultrafine particles from the fine particles at (c).

[0080] The method may further include classifying or sieving the atomized powder raw material to obtain the atomized powder before contacting the atomized powder with the removal liquid at (d).

[0081] In certain exemplary aspects, the atomized powder may be a first batch of atomized powder, and the method may further include: receiving the separated removal liquid and detached ultrafine particles in the recirculation loop at (e); filtering the detached ultrafine particles from the removal liquid in the recirculation loop at (f); and providing the filtered removal liquid back to the first batch of atomized powder, or the second batch of atomized powder at (g).

[0082] It should be understood that previous thinking has been that it is undesirable to expose reactive metal powders to moisture because moisture is generally believed to increase cohesion between fine particles, especially between ultrafine particles and fine particles. In this way, the conventional thinking is that exposing reactive metal powders to moisture will reduce the flowability of the resulting powder. However, the inventors of the present invention have unexpectedly discovered that by exposing the reactive metal powder to a sufficient amount of 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 result in a significant improvement in the flowability of the reactive metal powder after drying.

[0083] In particular, powder flowability (i.e. its flowability, F RMP ) is measured using the Hall test according to ASTM B213-20. It has been found that the removal of ultrafine particles from the atomized powder according to the present invention has an effect on the flowability F of the resulting metal powder. RMP Provides significant benefits. Flow F RMP The increase in can provide significant benefits in, for example, the additive manufacturing industry as well as other industries.

[0084] The inventors have found that the particle size S of the finished metal powder RMP (and each having a size S RMP The average mass of the particles M C ) and the apparent density D of the finished metal powder RMP All of them affect the volume flowability of the finished metal powder. VRMP For example, larger particles generally have improved bulk flow properties compared to smaller powders with similar properties. VRMP , and higher density finished metal powders also generally have improved flow properties compared to lower density finished metal powders with similar properties. RMP .

[0085] In order to function in a desired manner in, for example, an additive manufacturing machine, the inventors have found that a minimum volume flowability F should be achieved. VRMP These volume flows F VRMP This can be achieved using improvements associated with the methods and systems described herein. Finished metal powders that exhibit flow characteristics below these thresholds may not function in a desired manner and may, for example, clog or slow down production using the powder. The inventors have discovered the following relationship that provides the above benefits: Volume flowability, F VRMP The size of the particles in the finished metal powder, S RMP ; Apparent density, D RMP ; Size is S RMP The average mass of each particle M C ; and the bulk density of the alloy D BULK :

[0086] F VRMP ≥0.3×ln(M C )+2,

[0087] Among them, M C Size S RMP The average mass of the particles is between 0.001 μg and 1 μg. C is calculated by calculating the radius equal to the size S RMP half of the alloy’s bulk density D BULKThe mass of the sphere is obtained. In particular, M C Use the following relationship to determine:

[0088]

[0089] Where S RMP is the D10 value (defined as the point on the particle size distribution curve measured according to ASTM B822-20 below which 10% of the particles are below) and is between 5 μm and 30 μm. The equipment used to carry out the measurement method is a Beckman Coulter LS 13320. D BULK is the bulk density of the alloy, which can be obtained by ASTM B923-22. In the above relationship, D BULK It can be between 1.5 and 20 grams per cubic centimeter. There are a variety of instruments available for quantifying particle size by laser diffraction following ASTM B822-20. These include the Beckman Coulter TM LS 13 320、Cilas990L TM Malvern TM Mastersizer TM 、Sympatec TM HELOS TM 、Microtrac TM Particle Size Analyzer S3500 TM Etc. It is understood that there may be inherent variability in the D10 values ​​obtained from a particular powder tested using existing equipment under the guidance of ASTM B822-20. For the purposes of this disclosure, the D10 value ranges provided herein refer to powders that demonstrate D10 values ​​within the disclosed and / or claimed ranges when tested in accordance with ASTM B822-20 using at least one recognized method and equipment.

[0090] F VRMP is the volume flow rate and is between 0.1 cubic centimeters per second and 1.4 cubic centimeters per second. VRMP Obtained by dividing the 50 g used in the Hall flow test (according to ASTM B213-20) by the time required for the powder to flow through the funnel (F HFT , expressed in seconds), and then divided by the apparent density D RMP (Expressed in grams per cubic centimeter and obtained according to ASTM B212-21). Volume flowability F VRMP The final unit is cubic centimeters divided by seconds. D measured according to ASTM B212-21 RMP Between 0.8 g / cm3 and 11 g / cm3. In particular, F VRMP It is obtained through the following relationship:

[0091] F VRMP =(50 / F HFT ) / D RMP .

[0092] Reference Figure 7 and Figure 8 , various exemplary powders are described according to one or more exemplary embodiments of the present invention. In particular, Figure 7 Provides corresponding Figure 8 Table of values ​​for several exemplary powders. Figure 8 Shown is a graph 400 of a powder according to one or more exemplary embodiments of the present disclosure, showing the volume flowability F on the Y-axis 402. VRMP and the dimension on the X axis 404 is S RMP The average weight of the particles M C .

[0093] As shown in the figure, Figure 8 The curve 400 in FIG. 4 depicts a first range 406, where the mobility F VRMP Greater than or equal to 0.3×ln(M C )+2 (line 408) and is less than or equal to 0.3×ln(M C )+2.4(line 410).

[0094] As shown in the figure, Figure 8 In the exemplary embodiment shown, the powder comprises a bulk flowability F VRMP Titanium alloys (such as Ti-6Al-4V) between 0.35 and 1.05; volume flowability F VRMP Nickel or nickel alloy with volume flowability F between 0.7 and 1.1 VRMP Niobium or niobium alloys having a volume flowability F between 1.0 and 1.2; VRMP Aluminium or aluminium alloys between 0.2 and 0.5.

[0095] Reference now Fig. 9 , a table of four examples of reactive metal powders illustrates the benefits of the method of the present invention.

[0096] Example 1. The first batch of titanium alloy includes a first batch of atomized powder before removing ultrafine particles and a second batch of atomized powder after removing ultrafine particles. The ultrafine particle removal process of this embodiment includes mixing the atomized powder with water, adding ultrasonic energy, and filtering on a 15μm sieve. It can be seen that the ultrafine particle removal process results in a slight increase in D10 (an increase greater than 0% and an increase less than 10%, such as an increase less than 5%), a slight decrease in the portion below 10μm, and a significant increase in fluidity (between 10% improvement and 100% improvement, such as between 25% improvement and 50% improvement).

[0097] Example 2. The second batch was a nickel alloy, processed in the same manner as the first batch (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 (greater than 0% increase and less than 10% increase), a slight decrease in the fraction below 10 μm, and a significant increase in flowability (between 10% improvement and 100% improvement).

[0098] Example 3. The third batch was a niobium alloy, processed in the same manner as the first batch (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 (an increase greater than 0% and an increase less than 10%, such as an increase less than 5%), no measurable change in the fraction less than 10 μm, and a significant increase in flowability (between a 10% improvement and a 100% improvement).

[0099] Example 4. The fourth batch of aluminum alloy similarly includes the first batch of atomized powder before removing ultrafine particles and the second batch of atomized powder after removing ultrafine particles. The ultrafine particle removal process of this embodiment includes spraying the atomized powder with a fluorocarbon liquid and filtering on a 20μm sieve. In this way, it can be understood that the mixture of atomized powder and removal liquid (fluorocarbon liquid in Example 4) is filtered on a sieve having a size smaller than the lower limit of the particle size distribution of the tested atomized powder. It can be seen that the ultrafine particle removal process results in a slight increase in D10 (an increase greater than 0% and an increase less than 20%), a reduction in the portion below 10μm, and a significant increase in fluidity (between 10% improvement and 100% improvement, for example, between 25% improvement and 50% improvement).

[0100] In this way, it can be understood that the D10 value is substantially unaffected by the ultrafine powder removal process.

[0101] Other aspects are provided by the following subjects:

[0102] 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, wherein contacting the atomized powder with the removal liquid comprises 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.

[0103] The method of any preceding clause, wherein the atomized powder has a particle size distribution of 0 μm to 150 μm.

[0104] A method as claimed in any preceding clause, wherein the atomised powder is a reactive metal powder.

[0105] The method of any of the preceding clauses, 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.

[0106] The method of any preceding clause, wherein the reactive metal powder is aluminum or an aluminum alloy, and wherein the removal liquid is a halocarbon liquid.

[0107] The method of any preceding clause, further comprising: prior to contacting the atomized powder with the removal liquid, sieving the raw metal powder to obtain the atomized powder.

[0108] The method of any of the preceding clauses, wherein screening the raw atomized powder comprises dry screening the raw metal powder or wet screening the raw metal powder.

[0109] The method of any of the preceding clauses, wherein adding energy to the atomized powder and liquid removal mixture comprises exposing the mixture to ultrasonic energy, mechanically agitating the mixture, adding kinetic energy from a liquid stream, or a combination thereof.

[0110] The method of any preceding clause, wherein adding energy to the mixture of atomized powder and removal liquid comprises spraying the atomized powder with the removal liquid.

[0111] The method of any of the preceding clauses, wherein the removal liquid is water, an organic or inorganic solvent, a halocarbon liquid, a fluorocarbon liquid, or a combination thereof.

[0112] The method of any of the preceding clauses, wherein the fine particles are formed into a finished product quality M 成品 The finished metal powder is obtained by mixing the atomized powder with the removal liquid, and wherein the atomized powder has an initial mass M before the atomized powder is contacted with the removal liquid. 初始 , and where M 成品 With M 初始 The ratio is greater than 0.90.

[0113] The method of any of the preceding clauses, wherein the atomized powder is a first batch of atomized powder, and wherein the method further comprises: 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 of atomized powder or the second batch of atomized powder.

[0114] A method as claimed in any preceding clause, wherein adding energy to the mixture of atomised powder and removed liquid comprises exposing the mixture to ultrasonic energy.

[0115] A method as claimed in any preceding clause, wherein adding energy to the mixture of atomised powder and removed liquid comprises mechanically agitating the mixture.

[0116] A method as claimed in any preceding clause, wherein adding energy to the mixture of atomised powder and removed liquid comprises adding kinetic energy to the liquid stream.

[0117] An ultrafine particle removal system includes: a container having a mixing chamber for receiving atomized powder, the container also including an ultrafine particle filter exposed to the mixing chamber; a fluid nozzle in fluid communication with the mixing chamber for providing a removal liquid to the mixing chamber; and a recirculation assembly fluidly connected to the mixing chamber at a position downstream of the ultrafine particle filter and further fluidly connected to the fluid nozzle, the recirculation assembly including a fine filter for removing ultrafine particles from a mixture received from the mixing chamber.

[0118] The ultrafine particle removal system of any preceding clause, wherein the atomized powder has a particle size distribution of 0 μm to 150 μm.

[0119] The ultrafine particle removal system of any of the preceding clauses, 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.

[0120] The ultrafine particle removal system described in any of the preceding clauses further includes a mixer located in the mixing chamber for adding energy to the mixture of the atomized powder and the removal liquid.

[0121] The ultrafine particle removal system of any of the preceding clauses, wherein the mixer comprises one or more blades and a shaft, the one or more blades being mounted on the shaft and configured to rotate about the axis of the shaft to add energy to the mixture.

[0122] The ultrafine particle removal system of any of the preceding clauses, wherein the ultrafine particle filter has a plurality of openings, the diameter of the openings being between 5 μm and 10 μm

[0123] An ultrafine particle removal system as described in any of the preceding clauses, wherein the container further includes a barrier layer that selectively isolates the ultrafine particle filter from the mixing chamber fluid, the barrier layer comprising a wall having a plurality of openings and a corresponding plurality of flapper valves located within each of the plurality of openings.

[0124] An atomized powder mixture comprising: a reactive metal powder comprising a fine powder formed of a reactive metal, wherein the reactive metal powder has a volume flowability F in cubic centimeters per second measured according to ASTM B213-20 VRMP and the bulk density D in grams per cubic centimeter BULK wherein the particles of the reactive metal powder have a size S in micrometers corresponding to the D10 value of the reactive metal powder measured according to ASTM B822-20 RMP and the average mass M in μg C ; wherein the reactive metal powder has been treated to remove ultrafine metal powder from fine powder so that the volume flowability FVRMP is greater than or equal to 0.3×ln(M C )+2, and the average mass M C equal

[0125]

[0126] Where S RMP Between 5 μm and 30 μm, F VRMP Between 0.1 cubic centimeters per second and 1.4 cubic centimeters per second, D BULK Between 1.5 and 20 grams per cubic centimeter.

[0127] The atomized powder mixture of any of the preceding clauses, wherein the reactive metal powder comprises titanium, titanium alloy, zirconium, zirconium alloy, magnesium, magnesium alloy, aluminum, aluminum alloy, nickel, nickel alloy, niobium, niobium alloy or a combination thereof.

[0128] The atomized powder mixture of any of the preceding clauses, wherein the reactive metal powder comprises 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, tungsten alloys, or combinations thereof.

[0129] An atomized powder mixture as described in any of the preceding clauses, wherein the reactive metal powder has a particle size distribution between 0 μm and 150 μm.

[0130] An atomized powder mixture according to any of the preceding clauses, wherein F VRMP Less than or equal to 0.3×ln(M C )+2.4.

[0131] The atomized powder mixture of any of the preceding clauses, wherein the reactive metal powder has an apparent density D in grams per cubic centimeter measured according to ASTM B212-21. RMP , where D RMP Between 0.8 and 11 grams per cubic centimeter.

[0132] The atomized powder mixture of any of the preceding clauses, wherein the reactive metal powder has a flowability F of 0.040 in a Hall flow test. HFT , and wherein the volume flowability F VRMP equal:

[0133] F VRMP =(50 / F HFT ) / D RMP .

[0134] An atomized powder mixture is formed using the method described in any of the preceding clauses.

[0135] An atomized powder mixture is formed using any of the ultrafine particle removal systems described above.

[0136] This written description uses examples to disclose the invention, including the best mode, and to enable any person skilled in the art to practice the invention, including making and using any devices or systems, and performing 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 include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements that are insubstantially different from the literal language of the claims.

Claims

1. A method for removing ultrafine particles from an atomized powder, the method comprising: contacting an atomized powder with a removal liquid to form a mixture of the atomized powder and the removal liquid, the atomized powder comprising fine particles and ultrafine particles; Adding energy to the mixture of atomized powder and removal liquid to separate ultrafine particles from fine particles; as well as The liquid is removed and the detached ultrafine particles are separated from the fine particles.

2. The method according to claim 1, wherein: The atomized powder has a particle size distribution of 0 μm to 150 μm.

3. The method according to claim 1, wherein: The atomized powder is a reactive metal powder.

4. The method according to claim 3, wherein: The reactive metal powder includes 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, tungsten alloys, or combinations thereof.

5. The method according to claim 3, wherein: The reactive metal powder is aluminum or an aluminum alloy, and the removal liquid is a halocarbon liquid.

6. The method according to claim 1, wherein: The method further comprises: Prior to contacting the atomized powder with the removal liquid, the raw metal powder is sieved to obtain the atomized powder.

7. The method according to claim 1, wherein: The fine particles form a finished metal powder having a finished quality M 成品 , and before the atomized powder contacts the removal liquid, the atomized powder has an initial mass M 初始 , and M 成品 With M 初始 The ratio is greater than 0.

90.

8. The method according to claim 1, wherein: The atomized powder is a first atomized powder, and the method further comprises: receiving the separated removal liquid and the dislodged ultrafine particles in a recirculation loop; filtering ultrafine particles removed from the removal liquid within a recirculation loop; and The filtered removal liquid is provided to the first batch of atomized powder or the second batch of atomized powder.

9. An ultrafine particle removal system comprising: a container having a mixing chamber for receiving the aerosolized powder, the container further comprising an ultrafine particle filter exposed to the mixing chamber; a fluid nozzle in fluid communication with the mixing chamber for providing a removal liquid to the mixing chamber; and A recirculation assembly is fluidly connected to the mixing chamber at a location downstream of the ultrafine particle filter and is also fluidly connected to the fluid nozzle, the recirculation assembly including a particulate filter for removing ultrafine particles from the mixture received from the mixing chamber.

10. An atomized powder mixture comprising: A reactive metal powder comprising a fine powder formed of a reactive metal, in, The reactive metal powder has a volume flowability F in cubic centimeters per second measured according to ASTM B213-20. VRMP and the bulk density D in grams per cubic centimeter bulk ; The particles of the reactive metal powder have a size S in micrometers. RMP and the average mass M in micrograms C , the size S RMP Corresponds to the D10 value of the active metal powder measured according to ASTM B822-20; wherein the reactive metal powder has been processed to remove ultrafine metal powder from the fine powder so that the volume flowability F VRMP Greater than or equal to 0.3×ln(M C )+2, and Among them, the average mass M C equal Among them, S RMP Between 5 μm and 30 μm, F VRMP Between 0.1 cubic centimeters per second and 1.4 cubic centimeters per second, D BULK Between 1.5 and 20 grams per cubic centimeter.

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