Metal powder atomization manufacturing method

Abstract

A method for manufacturing active metal powder by atomization is provided. For example, such a method includes providing a heated metal source and contacting the heated metal source with at least one additive gas during the atomization process. This method provides raw active metal powder with improved flowability. The at least one additive gas can be mixed with an atomizing gas to obtain an atomized mixture, and the heated metal source can be contacted with the atomized mixture during the atomization process. A method for manufacturing active metal powder by spheroidization is also provided.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to US 62 / 247,794, filed October 29, 2015, which is incorporated herein by reference in its entirety.

[0003] open field

[0004] This disclosure relates to the field of producing spherical powders, such as active metal powders. More specifically, it relates to methods and apparatus for preparing active metal powders by improving flowability.

[0005] Public background

[0006] Typically, the desired characteristics of high-quality active metal powders are a combination of high sphericity, density, purity, flowability, and low gas rejection porosity. Fine powders can be used in applications such as 3D printing, powder injection molding, hot isostatic pressing, and coating. These fine powders are also suitable for aerospace, biomedical, and industrial applications.

[0007] Powders with poor flowability may tend to form agglomerates with lower density and higher surface area. These agglomerates can be detrimental when used in applications requiring finely powdered active metals. Furthermore, poorly flowable active powders can cause pipe blockage and / or adhesion to the walls of the atomizing chamber or delivery pipes of the atomizing device. Moreover, agglomerated powders are more difficult to sieve when separating powders into different size distributions. The higher surface area also translates to higher activity, thus increasing safety risks when handling powders in agglomerated form.

[0008] In contrast, metal powders with improved flowability are desirable for a number of reasons. For example, they can be more readily used in powder metallurgy methods in the form of additive manufacturing and coating.

[0009] Overview

[0010] Therefore, there is a strong desire to provide an apparatus, system, or method that will at least partially address the poor flowability of active metal powders associated with electrostatic sensitivity. High flowability powders typically translate to higher apparent density, and they can be more easily spread to produce a uniform powder layer.

[0011] According to one aspect, a method for manufacturing active metal powder by atomization is provided, comprising:

[0012] A metal source that provides heating; and

[0013] When performing the atomization method, the heated metal source is brought into contact with at least one additive gas.

[0014] According to another aspect, a method for manufacturing active metal powder by atomization is provided, comprising:

[0015] A metal source that provides heating; and

[0016] In performing the atomization method, the heated metal source is contacted with at least one additive gas to obtain a raw active metal powder, which includes...

[0017] Particle size distribution of approximately 10 μm to approximately 53 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0018] Particle size distribution of approximately 10 μm to approximately 45 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0019] Particle size distribution of approximately 15 μm to approximately 45 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0020] Particle size distribution of approximately 15 μm to approximately 53 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0021] Particle size distribution of approximately 25 μm to approximately 45 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0022] Particle size distribution of approximately 25 μm to approximately 53 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0023] Particle size distribution of approximately 45 μm to approximately 75 μm, with flowability of less than 28 s as measured according to ASTM B213;

[0024] Particle size distribution of approximately 45 μm to approximately 106 μm, with flowability of less than 28 s as measured according to ASTM B213;

[0025] A particle size distribution of approximately 45 μm to approximately 150 μm, with flowability of less than 28 s as measured according to ASTM B213; and / or

[0026] The particle size distribution is from approximately 45 μm to approximately 180 μm, with a flowability of less than 28 s as measured according to ASTM B213.

[0027] According to another aspect, a method for manufacturing active metal powder by atomization is provided, comprising:

[0028] Provides a metal source for heating;

[0029] The atomizing gas is mixed with at least one additive gas to obtain an atomized mixture;

[0030] When performing the atomization method, the heated metal source is brought into contact with the atomized mixture.

[0031] According to another aspect, a method for manufacturing active metal powder by atomization is provided, comprising:

[0032] Provides a metal source for heating;

[0033] The atomizing gas is mixed with at least one additive gas to obtain an atomized mixture;

[0034] In performing the atomization method, the heated metal source is brought into contact with the atomized mixture to obtain raw active metal powder, which includes...

[0035] Particle size distribution of approximately 10 μm to approximately 53 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0036] Particle size distribution of approximately 10 μm to approximately 45 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0037] Particle size distribution of approximately 15 μm to approximately 45 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0038] Particle size distribution of approximately 15 μm to approximately 53 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0039] Particle size distribution of approximately 25 μm to approximately 45 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0040] Particle size distribution of approximately 25 μm to approximately 53 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0041] Particle size distribution of approximately 45 μm to approximately 75 μm, with flowability of less than 28 s as measured according to ASTM B213;

[0042] Particle size distribution of approximately 45 μm to approximately 106 μm, with flowability of less than 28 s as measured according to ASTM B213;

[0043] A particle size distribution of approximately 45 μm to approximately 150 μm, with flowability of less than 28 s as measured according to ASTM B213; and / or

[0044] The particle size distribution is from approximately 45 μm to approximately 180 μm, with a flowability of less than 28 s as measured according to ASTM B213.

[0045] According to another aspect, a method for manufacturing metal powder by atomization is provided, comprising:

[0046] A metal source that provides heating; and

[0047] Under conditions sufficient to produce active metal powder, the heated metal source is contacted with at least one additive gas during the atomization method, the active metal powder having an addition amount of less than 1000 ppm of each of the electronegative atoms and / or molecules from the additive gas.

[0048] According to another aspect, a method for manufacturing metal powder by atomization is provided, comprising:

[0049] Provides a metal source for heating;

[0050] The atomizing gas is mixed with at least one additive gas to obtain an atomized mixture; and

[0051] Under conditions sufficient to produce pristine active metal powder, the heated metal source is brought into contact with the atomized mixture during the atomization method, wherein the pristine active metal powder has an addition amount of less than 1000 ppm of electronegative atoms and / or molecules from the added gas.

[0052] According to another aspect, a method for manufacturing metal powder by atomization is provided, comprising:

[0053] Provides a metal source for heating;

[0054] The atomizing gas is mixed with at least one additive gas to obtain an atomized mixture;

[0055] In performing the atomization method, the heated metal source is brought into contact with the atomized mixture to obtain raw metal powder;

[0056] The original active metal powder is sieved to obtain powder with a predetermined particle size; and

[0057] The powder having the predetermined particle size is brought into contact with water.

[0058] According to another aspect, a method for manufacturing active metal powder spheroids is provided, comprising:

[0059] Provide active metal powder sources; and

[0060] During the spheroidization method, the active metal powder source is brought into contact with at least one additive gas.

[0061] According to another aspect, a method for manufacturing active metal powder spheroids is provided, comprising:

[0062] Provide active metal powder sources; and

[0063] In performing the spheroidization method, the active metal powder source is contacted with at least one additive gas to obtain the original active metal powder, which includes...

[0064] Particle size distribution of approximately 10 μm to approximately 53 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0065] Particle size distribution of approximately 10 μm to approximately 45 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0066] Particle size distribution of approximately 15 μm to approximately 45 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0067] Particle size distribution of approximately 15 μm to approximately 53 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0068] Particle size distribution of approximately 25 μm to approximately 45 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0069] Particle size distribution of approximately 25 μm to approximately 53 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0070] Particle size distribution of approximately 45 μm to approximately 75 μm, with flowability of less than 28 s as measured according to ASTM B213;

[0071] Particle size distribution of approximately 45 μm to approximately 106 μm, with flowability of less than 28 s as measured according to ASTM B213;

[0072] A particle size distribution of approximately 45 μm to approximately 150 μm, with flowability of less than 28 s as measured according to ASTM B213; and / or

[0073] The particle size distribution is from approximately 45 μm to approximately 180 μm, with a flowability of less than 28 s as measured according to ASTM B213.

[0074] According to another aspect, a method for manufacturing active metal powder spheroids is provided, comprising:

[0075] Provides an active metal powder source;

[0076] The spheroidizing process gas is mixed with at least one additive gas to obtain a spheroidizing process gas mixture;

[0077] During the spheroidizing method, the active metal powder source is brought into contact with the spheroidizing process gas mixture.

[0078] According to another aspect, a method for manufacturing active metal powder spheroids is provided, comprising:

[0079] Provides an active metal powder source;

[0080] The spheroidizing process gas is mixed with at least one additive gas to obtain a spheroidizing process gas mixture;

[0081] During the spheroidizing method, the active metal powder source is brought into contact with the spheroidizing process gas mixture to obtain the original active metal powder, which includes...

[0082] Particle size distribution of approximately 10 μm to approximately 53 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0083] Particle size distribution of approximately 10 μm to approximately 45 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0084] Particle size distribution of approximately 15 μm to approximately 45 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0085] Particle size distribution of approximately 15 μm to approximately 53 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0086] Particle size distribution of approximately 25 μm to approximately 45 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0087] Particle size distribution of approximately 25 μm to approximately 53 μm, with flowability of less than 40 s as measured according to ASTM B213;

[0088] Particle size distribution of approximately 45 μm to approximately 75 μm, with flowability of less than 28 s as measured according to ASTM B213;

[0089] Particle size distribution of approximately 45 μm to approximately 106 μm, with flowability of less than 28 s as measured according to ASTM B213;

[0090] A particle size distribution of approximately 45 μm to approximately 150 μm, with flowability of less than 28 s as measured according to ASTM B213; and / or

[0091] The particle size distribution is from approximately 45 μm to approximately 180 μm, with a flowability of less than 28 s as measured according to ASTM B213.

[0092] According to another aspect, a method for manufacturing active metal powder spheroids is provided, comprising:

[0093] Provide active metal powder sources; and

[0094] Under conditions sufficient to produce pristine active metal powder, the active metal source is contacted with at least one additive gas during the spheroidization method, the pristine active metal powder having an addition amount of less than 1000 ppm of each of the electronegative atoms and / or molecules from the additive gas.

[0095] According to another aspect, a method for manufacturing active metal powder spheroids is provided, comprising:

[0096] Provides an active metal powder source;

[0097] The spheroidizing process gas is mixed with at least one additive gas to obtain a spheroidizing process gas mixture;

[0098] Under conditions sufficient to produce pristine active metal powder, the active metal powder source is contacted with the spheroidizing process gas mixture during the implementation of the spheroidizing method, wherein the pristine active metal powder has an addition amount of less than 1000 ppm of electronegative atoms and / or molecules from the added gas.

[0099] According to another aspect, a method for manufacturing metal powder spheroidization is provided, comprising:

[0100] Provides an active metal powder source;

[0101] The spheroidizing process gas is mixed with at least one additive gas to obtain a spheroidizing process gas mixture;

[0102] When implementing the atomization method, the active metal powder source is brought into contact with the spheroidization process gas mixture to obtain the original metal powder;

[0103] The active metal powder is sieved to obtain powder with a predetermined particle size;

[0104] The powder having the predetermined particle size is brought into contact with water.

[0105] According to another example, a method for preparing an active metal powder mixture is provided, comprising mixing an active metal powder obtained by the method described in this disclosure with an active metal powder obtained by a method different from those described in this disclosure.

[0106] According to another example, a method for preparing an active metal powder mixture is provided, comprising mixing an active metal powder obtained by the method described in this disclosure with an active metal powder obtained by a method different from those described in this disclosure.

[0107] According to another example, a method for preparing an active metal powder mixture is provided, comprising mixing active metal powder obtained by the metal powder atomization manufacturing method described in this disclosure with active metal powder obtained by the metal powder spheroidization manufacturing method described in this disclosure.

[0108] According to another example, an active metal powder obtained by the method described in this disclosure is provided.

[0109] This disclosure relates to methods, systems, and apparatus capable of producing active metal powders exhibiting high flowability. Effects can be observed on a variety of particle size distributions, including fine particle size distributions that do not flow even in a Hall flowmeter without the treatment described. One advantage of the current method is that it does not introduce foreign particles into the powder; it only results in improved surface treatment.

[0110] It has been observed that various techniques described in this disclosure help reduce the electrostatic sensitivity of powders, which leads to improved flowability properties of the powders.

[0111] Attached Figure

[0112] The attached figures illustrate non-limiting examples, in which:

[0113] Figure 1 This is a cross-sectional view of an exemplary atomization system;

[0114] Figure 2 This is a schematic diagram of active metal powder particles formed by atomization, wherein the heated metal source is not in contact with the added gas;

[0115] Figure 3 This is a schematic diagram of active metal powder particles formed by an atomization method, in which a heated metal source is in contact with an added gas.

[0116] Figure 4 A schematic diagram is shown of particles with radius R formed from the same mass of material, and multiple particles, each with radius r.

[0117] Figure 5 The TOF-SIMS signals of particles obtained from various tests are shown.

[0118] Figure 6 The photographs are of a batch of metal powder formed according to an atomization method that does not include the step of contact with the added gas; and

[0119] Figure 7 It is a photograph of a batch of metal powder formed by an atomization method in which the metal source has come into contact with the added gas.

[0120] Description of various implementation schemes

[0121] The following examples are presented in a non-restrictive manner.

[0122] When used in conjunction with the term "comprising" in the claims and / or specification, the words "a" or "an" may mean "a," but they also encompass the meanings of "one or more," "at least one," and "one or more than one," unless otherwise expressly stated. Similarly, the word "another" may mean at least a second or more, unless otherwise expressly stated.

[0123] The terms “comprising” (and any form of “comprising” such as “comprise” and “comprises”), “having” (and any form of “having” such as “have” and “has”), “including” (and any form of “including” such as “include” and “includs”), and “containing” (and any form of “containing” such as “contain” and “contains”) as used in this specification and claims are inclusive or open-ended and do not exclude other unrepresented elements or method steps.

[0124] When referring to methods, apparatus, or systems for preparing metal powders, the term "atomization zone" as used herein refers to the area where the material is atomized into material droplets. Those skilled in the art will understand that the size of the atomization zone will vary depending on various parameters, such as the temperature of the atomizing device, the speed of the atomizing device, the material in the atomizing device, the power of the atomizing device, the temperature of the material before entering the atomization zone, the properties of the material, the size of the material, and the resistivity of the material.

[0125] As used herein, the term "heated zone of an atomizer" refers to a region where the powder is sufficiently heated to react with the electronegative atoms of the added gas, thereby producing a depletion layer as discussed in this disclosure.

[0126] The statement "metal powder has a particle size distribution of X-Y μm" means that less than 5% wt. of its particles are larger than Y μm, where the latter value is measured according to ASTM B214. It also means that less than 6% wt. of its particles are smaller than X μm (d6 ≥ X μm), where the latter value is measured according to ASTM B822.

[0127] The description "metal powder with a particle size of 15-45 μm" means that less than 5% wt. of its particles are larger than 45 μm (measured according to ASTM B214) and less than 6% wt. of its particles are smaller than 15 μm (measured according to ASTM B822).

[0128] The term "gas-to-metal ratio" as used in this article refers to the ratio of the mass of injected gas per unit time (kg / s) to the mass feed rate (kg / s) of the metal source provided in the atomization zone.

[0129] As used herein, "active metal powder" refers to metal powders that cannot be effectively prepared using conventional gas atomization methods with tightly coupled nozzles. For example, such active metal powders may be powders containing at least one selected from titanium, titanium alloys, zirconium, zirconium alloys, magnesium, magnesium alloys, aluminum, and aluminum alloys.

[0130] As used in this article, the term "raw active metal powder" refers to active metal powder obtained directly from the atomization process without any post-processing steps (such as sieving or sorting techniques).

[0131] Active metal powders with fine particle sizes (e.g., within a particle size distribution below 106 μm) have been observed to have larger surface areas and stronger surface interactions. These result in poorer flowability compared to coarser powders. Powder flowability depends on one or more of a variety of factors, such as particle shape, particle size distribution, surface smoothness, humidity level, satellite content, and the presence of electrostatics. Therefore, powder flowability is a complex macroscopic characteristic arising from the balance between adhesive forces and gravity on the powder particles.

[0132] For example, the particle size distribution can be:

[0133] Approximately 10 μm to approximately 53 μm, exhibiting a flowability of less than 40 s as measured according to ASTM B213;

[0134] Approximately 10 μm to approximately 45 μm, exhibiting flowability of less than 40 s as measured according to ASTM B213;

[0135] Approximately 15μm to approximately 45μm, with a flowability of less than 40s as measured according to ASTM B213;

[0136] Approximately 15μm to approximately 53μm, with a flowability of less than 40s as measured according to ASTM B213;

[0137] Approximately 25μm to approximately 45μm, with a flowability of less than 40s as measured according to ASTM B213;

[0138] Approximately 25 μm to approximately 53 μm, exhibiting a flowability of less than 40 s as measured according to ASTM B213;

[0139] Approximately 45μm to approximately 75μm, with a flowability of less than 28s as measured according to ASTM B213;

[0140] Approximately 45 μm to approximately 106 μm, exhibiting a flowability of less than 28 s as measured according to ASTM B213;

[0141] Approximately 45 μm to approximately 150 μm, with a flowability of less than 28 s as measured according to ASTM B213; and / or

[0142] Approximately 45 μm to approximately 180 μm, with a flowability of less than 28 s as measured according to ASTM B213.

[0143] For example, the particle size distribution can be from about 10 μm to about 53 μm, with a flowability of less than 36 s as measured according to ASTM B213.

[0144] For example, the particle size distribution can be from about 10 μm to about 53 μm, with a flowability of less than 32 s as measured according to ASTM B213.

[0145] For example, the particle size distribution can be from about 10 μm to about 53 μm, with a flowability of less than 30 s as measured according to ASTM B213.

[0146] For example, the particle size distribution can be from about 10 μm to about 53 μm, with a flowability of less than 28 s as measured according to ASTM B213.

[0147] For example, the particle size distribution can be from about 10 μm to about 45 μm, with a flowability of less than 36 s as measured according to ASTM B213.

[0148] For example, the particle size distribution can be from about 10 μm to about 45 μm, with a flowability of less than 32 s as measured according to ASTM B213.

[0149] For example, the particle size distribution can be from about 10 μm to about 45 μm, with a flowability of less than 30 s as measured according to ASTM B213.

[0150] For example, the particle size distribution can be from about 10 μm to about 45 μm, with a flowability of less than 28 s as measured according to ASTM B213.

[0151] For example, the particle size distribution can be from about 15 μm to about 45 μm, with a flowability of less than 36 s as measured according to ASTM B213.

[0152] For example, the particle size distribution can be from about 15 μm to about 45 μm, with a flowability of less than 32 s as measured according to ASTM B213.

[0153] For example, the particle size distribution can be from about 15 μm to about 45 μm, with a flowability of less than 30 s as measured according to ASTM B213.

[0154] For example, the particle size distribution can be from about 15 μm to about 45 μm, with a flowability of less than 28 s as measured according to ASTM B213.

[0155] For example, the particle size distribution can be from about 15 μm to about 53 μm, with a flowability of less than 36 s as measured according to ASTM B213.

[0156] For example, the particle size distribution can be from about 15 μm to about 53 μm, with a flowability of less than 32 s as measured according to ASTM B213.

[0157] For example, the particle size distribution can be from about 15 μm to about 53 μm, with a flowability of less than 30 s as measured according to ASTM B213.

[0158] For example, the particle size distribution can be from about 15 μm to about 53 μm, with a flowability of less than 28 s as measured according to ASTM B213.

[0159] For example, the original active metal powder has a particle size distribution of about 25 μm to about 45 μm and a flowability of less than 36s as measured according to ASTM B213.

[0160] For example, the original active metal powder has a particle size distribution of about 25 μm to about 45 μm and a flowability of less than 32 s as measured according to ASTM B213.

[0161] For example, the original active metal powder has a particle size distribution of about 25 μm to about 45 μm and a flowability of less than 30 s as measured according to ASTM B213.

[0162] For example, the original active metal powder has a particle size distribution of about 25 μm to about 45 μm and a flowability of less than 25 s as measured according to ASTM B213.

[0163] For example, the original active metal powder has a particle size distribution of about 25 μm to about 53 μm and a flowability of less than 36s as measured according to ASTM B213.

[0164] For example, the original active metal powder has a particle size distribution of about 25 μm to about 53 μm and a flowability of less than 32 s as measured according to ASTM B213.

[0165] For example, the original active metal powder has a particle size distribution of about 25 μm to about 53 μm and a flowability of less than 30 s as measured according to ASTM B213.

[0166] For example, the original active metal powder has a particle size distribution of about 25 μm to about 53 μm and a flowability of less than 25 s as measured according to ASTM B213.

[0167] For example, the original active metal powder has a particle size distribution of about 45 μm to about 75 μm and a flowability of less than 26s as measured according to ASTM B213.

[0168] For example, the original active metal powder has a particle size distribution of about 45 μm to about 75 μm and a flowability of less than 25 s as measured according to ASTM B213.

[0169] For example, the original active metal powder has a particle size distribution of about 45 μm to about 75 μm and a flowability of less than 24 s as measured according to ASTM B213.

[0170] For example, the original active metal powder has a particle size distribution of about 45 μm to about 75 μm and a flowability of less than 23s as measured according to ASTM B213.

[0171] For example, the original active metal powder has a particle size distribution of about 45 μm to about 106 μm and a flowability of less than 26s as measured according to ASTM B213.

[0172] For example, the original active metal powder has a particle size distribution of about 45 μm to about 106 μm and a flowability of less than 25 s as measured according to ASTM B213.

[0173] For example, the original active metal powder has a particle size distribution of about 45 μm to about 106 μm and a flowability of less than 24 s as measured according to ASTM B213.

[0174] For example, the original active metal powder has a particle size distribution of about 45 μm to about 106 μm and a flowability of less than 23s as measured according to ASTM B213.

[0175] For example, the original active metal powder has a particle size distribution of about 45 μm to about 150 μm and a flowability of less than 26s as measured according to ASTM B213.

[0176] For example, the original active metal powder has a particle size distribution of about 45 μm to about 150 μm and a flowability of less than 25 s as measured according to ASTM B213.

[0177] For example, the original active metal powder has a particle size distribution of about 45 μm to about 150 μm and a flowability of less than 24 s as measured according to ASTM B213.

[0178] For example, the original active metal powder has a particle size distribution of about 45 μm to about 150 μm and a flowability of less than 23s as measured according to ASTM B213.

[0179] For example, the original active metal powder has a particle size distribution of about 45 μm to about 180 μm and a flowability of less than 26s as measured according to ASTM B213.

[0180] For example, the original active metal powder has a particle size distribution of about 45 μm to about 180 μm and a flowability of less than 25 s as measured according to ASTM B213.

[0181] For example, the original active metal powder has a particle size distribution of about 45 μm to about 180 μm and a flowability of less than 24 s as measured according to ASTM B213.

[0182] For example, the original active metal powder has a particle size distribution of about 45 μm to about 180 μm and a flowability of less than 23s as measured according to ASTM B213.

[0183] For example, in the atomization zone of the atomizer, a heated metal source is brought into contact with the at least one added gas.

[0184] For example, within the heating zone of the atomizer, a heated metal source is brought into contact with at least one of the added gases.

[0185] For example, the heated metal source is brought into contact with the at least one additive gas for substantially the same amount of time as the atomizing gas.

[0186] For example, the atomizing gas is an inert gas.

[0187] For example, the atomizing gas is mixed with the additive gas before it comes into contact with a heated metal source.

[0188] For example, contact with the added gas results in the formation of a first layer and a second layer on the surface of the original metal particles. The first layer contains atoms of the heated metal and atoms and / or molecules of the added gas. The first layer is a depletion layer that is deeper and thicker than the natural oxide layer, and the second layer is the natural oxide layer.

[0189] For example, the first layer has a substantially positive charge and the second layer has a substantially negative charge, and the first and second layers have a substantially neutral combined charge.

[0190] For example, the method also includes:

[0191] After the heated metal source is atomized, the original active metal powder is sieved to separate the original active metal powder by particle size distribution.

[0192] For example, the method also includes:

[0193] After sieving, the raw material powders are separated by stirring in water.

[0194] For example, the water is distilled water or demineralized water.

[0195] For example, the flowability of active metal powder can be measured based on dry, sieved metal powder after stirring.

[0196] For example, the active metal powder has an addition of less than 1000 ppm of each of the electronegative atoms and / or molecules from the added gas.

[0197] For example, the active metal powder has an addition of less than 500 ppm of each of the electronegative atoms and / or molecules from the added gas.

[0198] For example, the active metal powder has an addition amount of less than 250 ppm for each of the electronegative atoms and / or molecules from the added gas.

[0199] For example, the active metal powder has an addition amount of less than 200 ppm for each of the electronegative atoms and / or molecules from the added gas.

[0200] For example, the active metal powder has an addition of less than 150 ppm of each of the electronegative atoms and / or molecules from the added gas.

[0201] For example, the active metal powder has an addition amount of less than 100 ppm for each of the electronegative atoms and / or molecules from the added gas.

[0202] For example, the predetermined particle size includes any particle size distribution of about 10-53 μm, such as 10-45 μm, 15-45 μm, 10-53 μm, 15-53 μm and / or 25-45 μm.

[0203] For example, at least one of the added gases is an oxygen-containing gas.

[0204] For example, at least one of the added gases is an oxygen-containing gas selected from O2, CO2, CO, NO2, air, water vapor, and mixtures thereof.

[0205] For example, at least one of the added gases is a halogenated gas.

[0206] For example, halogens are F, Cl, Br, or I.

[0207] For example, at least one of the added gases is a hydrogen-containing gas.

[0208] For example, at least one of the added gases is a sulfur-containing gas.

[0209] For example, at least one of the added gases is a nitrogen-containing gas.

[0210] For example, at least one of the added gases is selected from O2, H2O, CO, CO2, NO2, N2, NO3, Cl2, SO2, SO3 and mixtures thereof.

[0211] For example, the active metal powder contains at least one of titanium, zirconium, magnesium, and aluminum.

[0212] For example, active metal powder is a metal powder containing at least one selected from titanium, titanium alloys, zirconium, zirconium alloys, magnesium, magnesium alloys, aluminum, and aluminum alloys.

[0213] For example, active metal powders contain titanium.

[0214] For example, active metal powders may contain titanium alloys.

[0215] For example, active metal powders contain zirconium.

[0216] For example, active metal powders may contain zirconium alloys.

[0217] For example, active metal powder is a metal powder containing at least one selected from titanium and titanium alloys.

[0218] For example, the method can be implemented using at least one plasma torch.

[0219] For example, the method can be implemented using at least one plasma torch.

[0220] For example, at least one plasma torch is a radio frequency (RF) plasma torch.

[0221] For example, at least one plasma torch is a direct current (DC) plasma torch.

[0222] For example, at least one plasma torch is a microwave (MW) plasma torch.

[0223] Now for reference Figure 1The diagram shows a cross-section of an example of an atomizing system 2'. The atomizing system 2' includes a container 8 that receives feed from a metal source 16 of an upstream system. For example, the feed to the metal source 16 is provided as a molten stream, but it can also be provided as a metal rod or wire. The metal source can be heated according to various techniques.

[0224] A heated metal source 16 is supplied to the atomization zone 32 through outlet 24, where it immediately comes into contact with the atomizing fluid from the atomization source 40. The contact between the heated metal source 16 and the atomizing fluid results in the formation of virgin active metal powder 64, which then exits from the atomization zone 32. For example, the atomizing fluid can be an atomizing gas. For example, the atomizing gas can be an inert gas.

[0225] For example, the inert gas can be selected from Ar and / or He.

[0226] It should be understood that although the atomization system 2' has an atomizing plasma torch 40, the methods and apparatus described herein for forming active metal powders with improved flowability can be applied to other types of spherical powder generation systems, such as shell melting gas atomization methods, electrode induction melting gas atomization methods (EIGA methods), plasma rotating electrode methods, plasma (RF, DC, MW) spheroidization methods, etc.

[0227] According to the illustrated example, the plasma source 40 includes at least one plasma torch. At least one discrete nozzle 48 of the at least one plasma torch 40 is located at the center of the metal source feed. For example, the cross-section of the nozzle 48 may be tapered in the direction toward the metal source feed to concentrate plasma in contact with the metal source feed. As described elsewhere herein, the nozzle 48 may be positioned such that the tip of the plasma jet contacts the metal source feed from container 8. The contact between the metal source feed and the plasma from the at least one plasma torch 40 results in metal source atomization.

[0228] In the case of providing multiple plasma torches, the nozzles of the torches are discrete nozzles 48 of the plasma torches oriented toward the metal source from container 8. For example, the discrete nozzles 48 are positioned such that the tip of the plasma jet output from them contacts the metal source from container 8.

[0229] According to several exemplary embodiments for preparing spherical powders, a heated metal source is contacted with at least one additive gas during the atomization method.

[0230] The added gas can be any gas containing electronegative atoms or molecules. Added gases can contain fluorine, chlorine, iodine, bromine, and hydrogen-based, nitrogen-based, and carbon-based compounds.

[0231] The added gas can be an oxygen-containing gas. As used in this article, "oxygen-containing gas" refers to a gas containing at least one oxygen atom. Examples of such gases include O2, CO2, CO, NO2, air, water vapor, and ozone.

[0232] According to several exemplary embodiments, within the atomization zone 32 of the atomizer, the added gas is brought into contact with a heated metal source 16. This atomization zone 32 is the high-heat zone of the atomizer. Therefore, within the atomization zone 32, the heated metal source 16 can come into contact with the atomizing gas and the added gas at substantially the same time.

[0233] The reaction between metal particles generated by atomization of a heated metal source and the added gas can occur, provided that the metal particles are hot enough to allow electronegative atoms and / or molecules to diffuse tens of nanometers into the surface layer.

[0234] It will be understood that, according to the various exemplary embodiments described herein, in addition to the contact between the heated metal source and the atomizing fluid, the gas added during the atomization process also comes into contact with the heated metal source.

[0235] It will be further understood that, according to existing atomization methods, some additive gases can be inherently introduced into the atomizing fluid, such as through contamination, potential impurities, or leaks. For example, the introduced additive gas may include air or oxygen.

[0236] However, according to several exemplary embodiments described herein for manufacturing spherical powders, an additive gas for contacting the heated metal source is intentionally provided in addition to any additive gas that may be introduced during the atomization process.

[0237] According to several exemplary embodiments, a first set of nozzles projects atomized fluid into an atomization zone 32 to contact the heated metal source 16, and a second set of nozzles injects an additive gas into the atomization zone 32 to contact the heated metal source 16. Alternatively, the second set of nozzles may mix the additive gas in the compatibility fluid with the atomized fluid before injecting the additive gas into the atomization zone 32. For example, the atomized fluid and the additive gas contact the heated metal source 16 substantially at the same time or shortly thereafter. For example, it is possible to mix the additive gas to dilute such additive gas and avoid excessive local concentrations that could lead to adverse or undesirable reactions.

[0238] According to several alternative exemplary embodiments, the atomizing fluid is an atomizing gas that is mixed with at least one additive gas to form an atomized mixture. For example, the atomizing gas is mixed with the additive gas before contact with a heated metal source. The atomizing gas and the additive gas can be mixed in a gas storage tank or pipeline upstream of the contact with the heated metal source. For example, the additive gas can be injected into an atomizing gas canister. The injected additive gas is a gas other than any additive gas inherently present in the atomizing gas.

[0239] The amount of added gas in contact with the heated metal source can be controlled based on the desired final properties of the active metal powder to be formed by the atomization process.

[0240] For example, the additive gas contained within the formed active metal powder can be considered a contaminant of the metal powder. Therefore, the amount of additive gas in contact with the heated metal source is controlled so that the atomic weight and / or molecular weight of the additive gas contained within the active metal powder are maintained within certain limits.

[0241] For example, the chemical composition limits within the active metal powder can be specified by appropriate standards, such as AMS4998, ASTM F3001, ASTM F2924, ASTM B348, ASTM B350 in Table 1, and ASTM B550 in Table 3. Therefore, the amount of additive gas in contact with the heated metal source is controlled based on the composition of the additive gas and the limits specified by standards for one or more atoms and / or molecules constituting the additive gas.

[0242] For example, when the added gas contains oxygen and the active metal powder to be formed is titanium alloy powder, the amount of added gas in contact with the heated metal source is controlled so that the amount of oxygen in the formed active metal powder is less than 1800 ppm according to AMS4998 and less than 1300 ppm according to ASTM F3001.

[0243] For example, when the added gas contains carbon and the active metal powder to be formed is titanium alloy powder, the amount of added gas in contact with the heated metal source is controlled so that the amount of carbon in the formed active metal powder is less than 1000 ppm according to AMS4998 and less than 800 ppm according to ASTM F3001.

[0244] For example, when the added gas contains hydrogen and the active metal powder to be formed is a titanium alloy powder, the amount of added gas in contact with the heated metal source is controlled so that the amount of hydrogen in the formed active metal powder is less than 120 ppm according to AMS4998 and ASTM F3001.

[0245] For example, when the added gas contains nitrogen and the active metal powder to be formed is a titanium alloy powder, the amount of added gas in contact with the heated metal source is controlled so that the amount of nitrogen in the formed active metal powder is less than about 400 ppm according to AMS4998 and less than 500 ppm according to ASTM F3001.

[0246] For example, in the case where the added gas contains chlorine and the active metal powder to be formed is titanium metal powder, the amount of added gas in contact with the heated metal source is controlled so that the amount of chlorine in the formed active metal powder is less than about 1000 ppm according to ASTM F3001.

[0247] For example, the amount of additive gas in contact with the heated metal source can be controlled by controlling the amount of additive gas injected into the atomizing gas during the formation of the atomized mixture. For example, the amount of additive gas injected can be controlled to achieve one or more desired ratio ranges of atomizing gas to additive gas in the formed atomized mixture.

[0248] For active metal powders formed without the addition of gas, it has been observed that active metal powders with a variety of different particle size distributions and that have undergone sieving and mixing steps are not always sufficiently fluid to allow their flowability to be measured in a Hall flowmeter (see [link]). Figure 1 (ASTM B213). For example, according to ASTM B213, active metal powder falling within a particle size distribution of 10-53 μm does not flow in a Hall flowmeter.

[0249] Without being bound by theory, a significant factor contributing to the poor flowability of activated metal powders is their sensitivity to electrostatics. Sieving, mixing, and handling processes can cause activated metal powder particles to collide with each other, thereby increasing the level of electrostatic charge. This electrostatic charge further generates cohesive forces between the particles, resulting in poor flowability of the activated metal powder.

[0250] The raw active metal powder, formed by atomization of the heated metal source through contact with both atomizing and additive gases, is further collected. The collected raw active metal powder comprises a mixture of metal particles of various sizes. The raw active metal powder is further sieved to separate it into different size distributions, such as 10–45 μm, 15–45 μm, 10–53 μm, 15–53 μm, and / or 25–45 μm.

[0251] After sieving, the metal powders of different particle sizes are stirred in distilled water or demineralized water. Stirring helps remove electrostatic charges accumulated on the surface of the metal powder particles.

[0252] After sieving, the metal powders of each particle size distribution were dried separately. It was observed that the active metal powders formed according to the various exemplary atomization methods described herein (where the heated metal source is in contact with the added gas) exhibited significantly higher flowability than those formed by atomization methods without contact with the added gas. This difference in flowability between metal powders formed according to different methods is primarily limited to metal powders with particle size distributions of 10-45 μm, 15-45 μm, 10-53 μm, 15-53 μm, and / or 25-45 μm or similar. However, it will be understood that metal powders with other size distributions may also exhibit a slight increase in flowability when formed according to methods including contacting the heated metal source with the added gas.

[0253] It is well known that titanium forms a natural surface oxide layer when exposed to air. This layer is typically about 3-5 nm long and consists primarily of titanium oxides (S. Axelsson, 2012, p. 37). The natural oxides function as a passivation layer and reduce reactivity. This natural layer has a strong affinity for water vapor (hydrophilicity) and possesses hydroxyl groups on its surface (Tanaka et al., 2008, p. 1; Lu et al., 2000, p. 1).

[0254] Without being bound by theory, during atomization, the contact between a heated metal source and an additive gas leads to the formation of active metal powder particles. As these particles form, the atoms and / or molecules of the additive gas react with them. Consequently, a first layer is formed on the outer surface of the active metal particles, consisting of a compound of the heated metal and the additive gas, and the additive gas is consumed through thickness. This layer is thicker and deeper at the surface and lies beneath the native oxide layer. For example, the compound of the heated metal and the additive gas in the depletion layer is a metal oxide, nitride, carbide, or halide. Because the atoms of the additive gas are consumed through the thickness of the surface layer, they form non-stoichiometric compounds with the metal. Such compounds give this first layer a fundamentally positive charge.

[0255] This first layer can only form at high temperatures because electronegative atoms and / or molecules need to have enough energy to diffuse into the surface layer more than the natural oxide layer.

[0256] A second layer, a natural oxide layer, is further formed on the surface of the active metal powder particles. The hydroxyl groups formed on the surface give the second layer a fundamentally negative charge.

[0257] A first layer with a substantially positive charge and a second layer with a substantially negative charge together form an electric double layer. The combined charge of the double layers has a substantially neutral charge (i.e., the net charge tends to zero). This neutral charge on the particle surface of an active metal powder may contribute to improved flowability of the active metal powder formed according to the exemplary methods and apparatus described herein. For example, while the net charge on the particles (such as particles formed according to conventional atomization methods) will favor particle polarization and increase interaction with other particles, weakly charged particles will have almost no electrical interaction with other particles. This reduced interaction may lead to better flowability.

[0258] Figure 2 This diagram illustrates particles 100 of an active metal powder formed according to an atomization method in which a heated metal source 16 is not in contact with an added gas. The formed particles 100 typically comprise a particle body 108 (e.g., Ti-6Al-4V particles) and a surface native oxide layer 116. The surface native oxide layer 116 typically has a negative charge, which makes the formed particles 100 have a non-net zero charge (i.e., Q for particle 108). net (≠0). This type of negative charge imparts a stronger polarization ability. Particle 108 also contains hydroxyl groups on its surface.

[0259] Figure 3 This diagram illustrates particles 140 of an active metal powder formed according to an exemplary atomization method described herein, in which a heated metal source 16 is in contact with an additive gas. A first layer 148 (or layer 1) is formed on the outer surface of a particle body 156 (e.g., a Ti-6Al-4V particle). It is produced by the recombination of heated metal with electronegative atoms and / or molecules consumed via thickness. A second layer 164 (or layer 2), a natural oxide layer, is further formed on the surface of the particle body 156. As described elsewhere herein, the first layer 148 and the second layer 164 have a substantially neutral combined charge, resulting in the formed particles 140 having a substantially zero net charge (Q). net (≈0) and low polarization ability.

[0260] Based on the theory that electronegative atoms and / or molecules from the additive gas become surface additives on the particles of the original metal powder formed, the amount of additive gas injected together with the atomizing gas to form the atomized mixture can be controlled because it varies quasi-linearly with the production rate of metal powder having a predetermined particle size distribution. The amount of additive gas required to form layer 1 is related to the total surface area of ​​the metal particles, which depends on the productivity and particle size distribution (see [link to relevant documentation]). Figure 4 The concentration of the added gas and the thermal state of the metal particles will determine the depth of the depletion layer in layer 1.

[0261] Furthermore, based on the theory that electronegative atoms and / or molecules from the additive gas become surface additives on the particles of the original metal powder formed, the amount of additive gas injected together with the atomizing gas to form the atomized mixture can be controlled, because it varies with... Figure 4 The total area of ​​the formed metal powder particles varies as shown.

[0262] Based further on the theory that electronegative atoms and / or molecules from the added gas become surface additives on the particles of the resulting original metal powder, the amount of added gas injected together with the atomizing gas to form the atomized mixture can be controlled, as it varies with the temperature of the surface of the particles of the resulting original metal powder. The reaction rate Ф of such a chemical reaction with activation energy E generally follows an Arhenius relationship with temperature T:

[0263]

[0264] Therefore, the injection efficiency of the added gas is higher at high temperatures, and a lower concentration of added gas is required to produce the desired depletion depth and form layer 1.

[0265] Figure 4 A schematic diagram is shown of a particle 180 with radius R and a depletion depth δ at the particle surface 188. The total surface area of ​​the particle is S1 = 4πR. 2 .

[0266] Figure 4 A further schematic diagram shows multiple particles (n particles) 200 of the same size and with the same total mass as particle 180. Particles 200 are smaller than particle 180, but they have a larger total surface area. Each particle 200 has a radius r, and the total number of particles is n = R. 3 / r 3 The combined surface area of ​​particle 200 is It increases linearly as the particle radius decreases.

[0267] Therefore, the amount of added surface additive is a function of the total surface area, since the volume to be processed is the product of the total surface area and the depletion depth.

[0268] For example, the obtained metal powder may have fewer than about 100 ppm, 150 ppm, 200 ppm, 300 ppm, 500 ppm, 1000 ppm or 1500 ppm of electronegative atoms and / or molecules (e.g. electronegative atom and / or molecular elements contained in the additive gas used to generate the powder).

[0269] Experiment 1

[0270] Apart from the composition of the atomized mixture in contact with a heated metal source, four different batches of powder were produced by plasma atomization under the same experimental conditions.

[0271] The atomizing gas is high-purity argon (≥99.997%).

[0272] In tests 1 and 2, the heated metal source was contacted only with the atomizing gas during the atomization process.

[0273] In Test 3, high-purity argon was injected into the air to form an atomized mixture of air and argon at 80 ppm. During the atomization process, heated metal was brought into contact with the atomized mixture.

[0274] In Test 4, O2 was injected into high-purity argon to form an atomized mixture of O2 and argon at 50 ppm. During the atomization process, heated metal was brought into contact with this second atomized mixture.

[0275] After contact with atomized gas (Tests 1 and 2) or atomized mixture (Tests 3 and 4), the resulting pristine active metal powder is sieved to separate a particle size distribution of 15–45 μm.

[0276] The sieved powders are then mixed to ensure homogeneity.

[0277] The powder is further stirred in distilled or demineralized water to remove the electrostatic charge that has accumulated in the previous steps.

[0278] The powder was dried in air at 80°C for 12 hours.

[0279] Figure 5 This is a graph showing a comparison of oxygen distribution between different samples using TOF-SIMS. The TOF-SIMS signals of the powders were obtained from tests 1 to 4. As can be seen in Table 1, the presence of a depletion layer may be associated with highly flowable powders.

[0280] Available from Figure 5 The TOF-SIMS signal of the processed fine powder is clearly visible. The oxygen content extends deeper into the surface layer. Obtaining this depletion layer with a specific critical depth is crucial for improved flow behavior. The TOF-SIMS results show a depletion layer depth of approximately 100 nm. This depth can be estimated by calibrating the sputtering rate of the ion beam obtained on the Ti-6Al-4V body using a profilometer. The sputtering rate depends on the ion beam intensity and material type. Calibration was performed before measurement, and the ion beam energy was highly stable.

[0281] Table 1: Description of flowability and apparent density based on 15-45 μm particle size distribution for tests 1 to 4

[0282]

[0283] Table 2: Chemical composition of powders from tests 1 to 4 based on 15-45 μm particle size distribution

[0284]

[0285] Table 3: Particle size distribution of tests 1 to 4 based on the 15-45 μm particle size distribution

[0286]

[0287] Statistical analysis of multiple batches determined that air injection (Test 3) added approximately 100-150 ppm of nitrogen and approximately 50 ppm of oxygen to the powder. Air injection improved the flowability of the resulting active metal powder.

[0288] Further analysis of statistical data confirmed that injecting only O2 (Test 4) added approximately 150-200 ppm of oxygen without adding nitrogen.

[0289] Other successful tests have been conducted on the flowability of the 15–45 μm particle size distribution by injecting water vapor. Improved flowability of the 15–45 μm particle size distribution has also been observed.

[0290] The treatment performed, based on the compositions specified in standards ASTM B348, ASTM F2924, and ASTM F3001, maintains a satisfactory chemical composition. If the oxygen content of the raw material were slightly higher, it would also conform to those standards of AMS 4998.

[0291] Figure 6 This is a photograph of a batch of approximately 100 kg of metal powder formed using an atomization method excluding contact with the added gas. Due to agglomerates, the collection bucket is 90% full and the compaction appears poor.

[0292] Figure 7 This is a photograph of a batch of approximately 100 kg of metal powder formed using an atomization method that involves contacting a metal source with an added gas. Due to the improved flowability and low surface interaction between particles, the collection bin is 20% filled with... Figure 6 The same amount of material was used during operation, and the visual compaction was good.

[0293] Similar tests to tests 3 and 4 have been conducted by intermittent injection of the added gas. The treatment was found to remain effective, while having the advantage of adding fewer impurities to the final product.

[0294] Similarly, it has been shown that a mixture containing up to 30% of powder with good flowability can be mixed with 70% of powder that does not flow in a Hall flowmeter, and the resulting powder still flows, even if not as well as the starting powder.

[0295] Experiment 2

[0296] The formed metal powder is then subjected to subsequent heat treatment, the powder being formed without the addition of gas.

[0297] More specifically, the formed metal powder was heated in air at approximately 250°C for 12 hours. This heating is expected to result in the addition of oxygen to the surface of the original metal powder particles and an increase in the thickness of the native oxide layer.

[0298] Subsequent oxidation / nitriding did not produce results similar to those obtained by contacting the added gas in the atomization zone of the atomization method. No improvement in the flowability of the metal powder was observed.

[0299] It appears that further heating of the already formed metal powder will only thicken the native oxide layer and will not provide sufficient depth and depletion of the oxide / nitride layer on the particle. A thicker oxide layer will also remain quasi-stoichiometric and will not provide the positively charged layer 1 provided by the depletion layer.

[0300] Without being bound by theory, when the metal source comes into contact with the additive gas, the high temperature and low concentration of the additive gas involved in atomization enable the oxidation / nitriding reaction that forms a depleted oxide / nitride layer to occur.

[0301] The embodiments described in paragraphs

[0027] through

[00192] of this disclosure are presented in this manner to demonstrate each combination of embodiments when applicable. Thus, these embodiments are presented in the specification in a form equivalent to causing the dependent claims to apply to all embodiments dependent on any of the preceding claims (covering the previously presented embodiments), thereby demonstrating that they can be combined in all possible ways. For example, this disclosure herein covers all possible combinations (where applicable) between the embodiments described in paragraphs

[0027] through

[00192] and the methods described in paragraphs

[0006] through

[0026] .

[0302] It will be understood that, for simplicity and clarity, reference numerals may be repeated in the accompanying drawings where deemed appropriate to indicate corresponding or similar elements or steps. Furthermore, numerous specific details are set forth to provide a comprehensive understanding of the exemplary embodiments described herein. However, those skilled in the art will understand that the embodiments described herein can be practiced without these specific details. In other instances, well-known methods, procedures, and components are not described in detail to avoid obscuring the embodiments described herein. Moreover, this description is not intended to limit the scope of the embodiments described herein in any way, but rather to describe only the implementation of the various embodiments described herein.

Claims

1. A method for manufacturing active metal powder by atomization, comprising: The heated active metal source is atomized to produce original active metal powder; During the atomization of the heated active metal source, the heated active metal source is contacted with an atomization mixture containing at least one atomizing gas and at least one additive gas, and the resulting raw active metal powder is heated sufficiently to react with the electronegative atoms of the additive gas to form a first layer, wherein the at least one additive gas is present in the atomization mixture at a concentration of less than 1000 ppm; and A surface layer is formed on the original active metal powder via the at least one additive gas, wherein the original active metal powder having the surface layer contains less than 1000 ppm of at least one element from the at least one additive gas. The surface layer comprises a first layer and a second layer. The first layer contains atoms of the heated active metal source and atoms and / or molecules of the at least one added gas. The first layer is a deeper and thicker depletion layer than the second layer. The second layer is a native oxide layer. The original active metal powder having the surface layer thereon with a particle size distribution of 10 µm to 53 µm has a flowability of less than 40 s as measured according to ASTM B213.

2. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 10 µm to 45 µm and has a flowability of less than 40 s as measured according to ASTM B213.

3. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 15 µm to 45 µm and has a flowability of less than 40 s as measured according to ASTM B213.

4. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 15 µm to 53 µm and has a flowability of less than 40 s as measured according to ASTM B213.

5. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 25 µm to 45 µm and has a flowability of less than 40 s as measured according to ASTM B213.

6. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 25 µm to 53 µm and has a flowability of less than 40 s as measured according to ASTM B213.

7. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 45 µm to 75 µm and has a flowability of less than 28 s as measured according to ASTM B213.

8. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 45 µm to 106 µm and has a flowability of less than 28 s as measured according to ASTM B213.

9. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 10 µm to 53 µm and has a flowability of less than 36 s as measured according to ASTM B213.

10. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 10 µm to 53 µm and has a flowability of less than 32 s as measured according to ASTM B213.

11. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 10 µm to 53 µm and has a flowability of less than 30 s as measured according to ASTM B213.

12. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 10 µm to 53 µm and has a flowability of less than 28 s as measured according to ASTM B213.

13. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 10 µm to 45 µm and has a flowability of less than 36 s as measured according to ASTM B213.

14. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 10 µm to 45 µm and has a flowability of less than 32 s as measured according to ASTM B213.

15. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 10 µm to 45 µm and has a flowability of less than 30 s as measured according to ASTM B213.

16. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 10 µm to 45 µm and has a flowability of less than 28 s as measured according to ASTM B213.

17. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 15 µm to 45 µm and has a flowability of less than 36 s as measured according to ASTM B213.

18. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 15 µm to 45 µm and has a flowability of less than 32 s as measured according to ASTM B213.

19. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 15 µm to 45 µm and has a flowability of less than 30 s as measured according to ASTM B213.

20. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 15 µm to 45 µm and has a flowability of less than 28 s as measured according to ASTM B213.

21. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 15 µm to 53 µm and has a flowability of less than 36 s as measured according to ASTM B213.

22. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 15 µm to 53 µm and has a flowability of less than 32 s as measured according to ASTM B213.

23. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 15 µm to 53 µm and has a flowability of less than 30 s as measured according to ASTM B213.

24. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 25 µm to 45 µm and has a flowability of less than 36 s as measured according to ASTM B213.

25. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 25 µm to 45 µm and has a flowability of less than 32 s as measured according to ASTM B213.

26. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 25 µm to 45 µm and has a flowability of less than 30 s as measured according to ASTM B213.

27. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 25 µm to 45 µm and has a flowability of less than 25 s as measured according to ASTM B213.

28. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 25 µm to 53 µm and has a flowability of less than 36 s as measured according to ASTM B213.

29. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 25 µm to 53 µm and has a flowability of less than 32 s as measured according to ASTM B213.

30. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 25 µm to 53 µm and has a flowability of less than 30 s as measured according to ASTM B213.

31. The method of claim 1, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 25 µm to 53 µm and has a flowability of less than 25 s as measured according to ASTM B213.

32. The method of claim 1, wherein the original active metal powder having the surface layer thereon further comprises a particle size distribution of 45 µm to 75 µm and has a flowability of less than 26 s as measured according to ASTM B213.

33. The method of claim 1, wherein the original active metal powder having the surface layer thereon further comprises a particle size distribution of 45 µm to 75 µm and has a flowability of less than 25 s as measured according to ASTM B213.

34. The method of claim 1, wherein the original active metal powder having the surface layer thereon further comprises a particle size distribution of 45 µm to 75 µm and has a flowability of less than 24 s as measured according to ASTM B213.

35. The method of claim 1, wherein the original active metal powder having the surface layer thereon further comprises a particle size distribution of 45 µm to 75 µm and has a flowability of less than 23 s as measured according to ASTM B213.

36. The method of claim 1, wherein the original active metal powder having the surface layer thereon further comprises a particle size distribution of 45 µm to 106 µm and has a flowability of less than 26 s as measured according to ASTM B213.

37. The method of claim 1, wherein the original active metal powder having the surface layer thereon further comprises a particle size distribution of 45 µm to 106 µm and has a flowability of less than 25 s as measured according to ASTM B213.

38. The method of claim 1, wherein the original active metal powder having the surface layer thereon further comprises a particle size distribution of 45 µm to 106 µm and has a flowability of less than 24 s as measured according to ASTM B213.

39. The method of claim 1, wherein the original active metal powder having the surface layer thereon further comprises a particle size distribution of 45 µm to 106 µm and has a flowability of less than 23 s as measured according to ASTM B213.

40. The method of any one of claims 1 to 39, wherein the heated active metal source is brought into contact with the at least one additive gas in the atomization zone of the atomizer.

41. The method of any one of claims 1 to 39, wherein the heated active metal source is brought into contact with the at least one additive gas within the heating zone of the atomizer.

42. The method of any one of claims 1 to 39, wherein the heated active metal source is contacted with the at least one additive gas for substantially the same duration as the contact with the atomizing gas.

43. The method of any one of claims 1 to 42, wherein the atomizing gas is an inert gas.

44. The method of claim 43, wherein the atomizing gas is mixed with the at least one additive gas before contacting the heated active metal source.

45. The method of any one of claims 1 to 44, wherein the first layer has a substantially positive charge and the second layer has a substantially negative charge, and wherein the first layer and the second layer have a substantially neutral combined charge.

46. ​​The method of any one of claims 1 to 45, further comprising: After the heated active metal source is atomized, the original active metal powder having the surface layer thereon is sieved to separate the original active metal powder having the surface layer thereon by particle size distribution.

47. The method of claim 46, further comprising: After the sieving, the separated original active metal powder having the surface layer thereon is stirred in water.

48. The method of claim 47, wherein the water is distilled water or demineralized water.

49. The method of claim 47 or 48, wherein the flowability of the active metal powder having the surface layer thereon is measured based on the dried, sieved active metal powder after stirring.

50. The method of any one of claims 1 to 49, wherein the surface layer comprises less than 500 ppm of at least one element from the at least one added gas.

51. The method of any one of claims 1 to 49, wherein the surface layer comprises less than 250 ppm of at least one element from the at least one added gas.

52. The method of any one of claims 1 to 49, wherein the surface layer comprises less than 200 ppm of at least one element from the at least one added gas.

53. The method of any one of claims 1 to 49, wherein the surface layer contains less than 150 ppm of at least one element from the at least one added gas.

54. The method of any one of claims 1 to 49, wherein the surface layer comprises less than 100 ppm of at least one element from the at least one added gas.

55. The method of any one of claims 1 to 49, wherein the surface layer has an addition amount of less than 500 ppm of an electronegative element from the at least one additive gas.

56. The method of any one of claims 1 to 49, wherein the surface layer has an added amount of less than 250 ppm of an electronegative element from the at least one added gas.

57. The method of any one of claims 1 to 49, wherein the surface layer has an addition amount of less than 200 ppm of an electronegative element from the at least one additive gas.

58. The method of any one of claims 1 to 49, wherein the surface layer has an added amount of less than 150 ppm of an electronegative element from the at least one added gas.

59. The method of any one of claims 1 to 49, wherein the surface layer has an added amount of less than 100 ppm of an electronegative element from the at least one added gas.

60. The method according to any one of claims 1 to 49, wherein, The original active metal powder is heated sufficiently to allow electronegative atoms and / or molecules of the added gas to diffuse into the surface layer at a depth of tens of nanometers. The method further includes: The original active metal powder having the surface layer thereon is sieved to obtain powder with a particle size of 10 µm to 53 µm or 45 µm to 180 µm; and The powder having a particle size of 10 µm to 53 µm or 45 µm to 180 µm is brought into contact with water.

61. The method of claim 60, wherein the powder has a particle size distribution of 10-45 μm, 15-45 μm, 10-53 μm, 15-53 μm or 25-45 μm.

62. A method for manufacturing active metal powder spheroids, comprising: An active metal powder source is contacted with a spheroidizing process gas mixture containing at least one spheroidizing process gas and at least one additive gas, while spheroidizing the active metal powder source to produce a raw active metal powder, which is sufficiently heated to react with electronegative atoms of the additive gas to form a first layer, wherein the at least one additive gas is present in the spheroidizing process gas mixture at a concentration of less than 1000 ppm. A surface layer is formed on the original active metal powder via the at least one additive gas, wherein the original active metal powder having the surface layer contains less than 1000 ppm of at least one element from the at least one additive gas, and The original active metal powder having the surface layer thereon is sieved to obtain powder with a particle size of 10 µm to 53 µm or 45 µm to 180 µm. The surface layer comprises a first layer and a second layer. The first layer contains atoms of a heated active metal source and atoms and / or molecules of the at least one added gas. The first layer is a depletion layer that is deeper and thicker than the second layer. The second layer is a native oxide layer. The original active metal powder having the surface layer thereon with a particle size distribution of 10 µm to 53 µm has a flowability of less than 40 s as measured according to ASTM B213.

63. The method of claim 62, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 10 µm to 45 µm and has a flowability of less than 40 s as measured according to ASTM B213.

64. The method of claim 62, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 15 µm to 45 µm and has a flowability of less than 40 s as measured according to ASTM B213.

65. The method of claim 62, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 15 µm to 53 µm and has a flowability of less than 40 s as measured according to ASTM B213.

66. The method of claim 62, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 25 µm to 45 µm and has a flowability of less than 40 s as measured according to ASTM B213.

67. The method of claim 62, wherein the original active metal powder having the surface layer thereon comprises a particle size distribution of 25 µm to 53 µm and has a flowability of less than 40 s as measured according to ASTM B213.

68. The method of claim 62, wherein the original active metal powder having the surface layer thereon further comprises a particle size distribution of 45 µm to 75 µm and has a flowability of less than 28 s as measured according to ASTM B213.

69. The method of claim 62, wherein the original active metal powder having the surface layer thereon further comprises a particle size distribution of 45 µm to 106 µm and has a flowability of less than 28 s as measured according to ASTM B213.

70. The method of any one of claims 62 to 69, wherein, The original active metal powder is heated sufficiently to allow electronegative atoms and / or molecules of the added gas to diffuse into the surface layer at a depth of tens of nanometers. The method further includes: The original active metal powder having the surface layer thereon is sieved to obtain powder with a particle size of 10 µm to 53 µm or 45 µm to 180 µm. The powder having a particle size of 10 µm to 53 µm or 45 µm to 180 µm is brought into contact with water.

71. The method of claim 1, wherein, The original active metal powder is heated sufficiently to allow electronegative atoms and / or molecules of the added gas to diffuse into the surface layer at a depth of tens of nanometers. The method further includes: The original active metal powder having the surface layer thereon is sieved to obtain powder with a particle size of 10 µm to 53 µm or 45 µm to 180 µm. The original active metal powder having the surface layer thereon with a particle size of 10 µm to 53 µm or 45 µm to 180 µm is stirred in water.

72. The method of any one of claims 1 to 71, wherein the at least one added gas is an oxygen-containing gas.

73. The method according to any one of claims 1 to 71, wherein the at least one added gas is an oxygen-containing gas selected from O2, CO2, CO, NO2, air, water vapor, and mixtures thereof.

74. The method of any one of claims 1 to 71, wherein the at least one added gas is a halogen-containing gas.

75. The method of claim 74, wherein the halogen is F, Cl, Br or I.

76. The method of any one of claims 1 to 71, wherein the at least one added gas is a hydrogen-containing gas.

77. The method of any one of claims 1 to 71, wherein the at least one added gas is a sulfur-containing gas.

78. The method of any one of claims 1 to 71, wherein the at least one added gas is a nitrogen-containing gas.

79. The method according to any one of claims 1 to 71, wherein the at least one added gas is selected from: O2, H2O, CO, CO2, NO2, N2, NO3, Cl2, SO2, SO3 and mixtures thereof.

80. The method of any one of claims 1 to 79, wherein the original active metal powder having the surface layer thereon comprises at least one of titanium, zirconium, magnesium and aluminum.

81. The method of any one of claims 1 to 79, wherein the original active metal powder having the surface layer thereon is a metal powder comprising at least one selected from titanium, titanium alloys, zirconium, zirconium alloys, magnesium, magnesium alloys, aluminum, and aluminum alloys.

82. The method of any one of claims 1 to 79, wherein the original active metal powder having the surface layer thereon comprises titanium.

83. The method of any one of claims 1 to 79, wherein the original active metal powder comprises a titanium alloy.

84. The method of any one of claims 1 to 79, wherein the original active metal powder having the surface layer thereon comprises zirconium.

85. The method of any one of claims 1 to 79, wherein the original active metal powder having the surface layer thereon comprises a zirconium alloy.

86. The method of any one of claims 1 to 79, wherein the original active metal powder having the surface layer thereon is a metal powder comprising at least one selected from titanium and titanium alloys.

87. The method of any one of claims 1 to 86, wherein the method is carried out by at least one plasma torch.

88. The method of claim 87, wherein the at least one plasma torch is a radio frequency (RF) plasma torch.

89. The method of claim 87, wherein the at least one plasma torch is a direct current (DC) plasma torch.

90. The method of claim 87, wherein the at least one plasma torch is a microwave (MW) plasma torch.

91. A method for preparing an active metal powder mixture, comprising mixing an active metal powder obtained by any one of claims 1 to 90 with an active metal powder obtained by a method different from any one of claims 1 to 90.

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