Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/02—Making metallic powder or suspensions thereof using physical processes
  • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
  • B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
  • B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/05—Metallic powder characterised by the size or surface area of the particles
  • B22F1/052—Metallic powder characterised by the size or surface area of the particles characterised by a mixture of particles of different sizes or by the particle size distribution
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/06—Metallic powder characterised by the shape of the particles
  • B22F1/065—Spherical particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
  • B22F1/14—Treatment of metallic powder
  • B22F1/142—Thermal or thermo-mechanical treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F10/00—Additive manufacturing of workpieces or articles from metallic powder
  • B22F10/70—Recycling
  • B22F10/73—Recycling of powder
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/02—Making metallic powder or suspensions thereof using physical processes
  • B22F9/14—Making metallic powder or suspensions thereof using physical processes using electric discharge
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B33—ADDITIVE MANUFACTURING TECHNOLOGY
  • B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
  • B33Y70/00—Materials specially adapted for additive manufacturing
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C33/00—Making ferrous alloys
  • C22C33/02—Making ferrous alloys by powder metallurgy
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F2009/001—Making metallic powder or suspensions thereof from scrap particles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F9/00—Making metallic powder or suspensions thereof
  • B22F9/02—Making metallic powder or suspensions thereof using physical processes
  • B22F9/06—Making metallic powder or suspensions thereof using physical processes starting from liquid material
  • B22F9/08—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying
  • B22F9/082—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid
  • B22F2009/0836—Making metallic powder or suspensions thereof using physical processes starting from liquid material by casting, e.g. through sieves or in water, by atomising or spraying atomising using a fluid with electric or magnetic field or induction
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2202/00—Treatment under specific physical conditions
  • B22F2202/13—Use of plasma
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
  • B22F2998/10—Processes characterised by the sequence of their steps
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2999/00—Aspects linked to processes or compositions used in powder metallurgy
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
  • Y02P10/00—Technologies related to metal processing
  • Y02P10/25—Process efficiency

Definitions

• Powder is injected from the side, either perpendicularly or at an angle, into the plasma plume, where it is melted by the high temperature of the plasma. Surface tension of the melt pulls it into a spherical shape, then it is cooled, solidified and is collected in filters.
• An issue with thermal arc plasma is that the electrodes used to ignite the plasma are exposed to the high temperature causing degradation of the electrodes, which contaminates the plasma plume and process material.
• thermal arc plasma plume inherently exhibit large temperature gradient.
• the plasma is produced by a varying magnetic field that induces an electric field in the plasma gas, which in turn drives the plasma processes such as ionization, excitation, etc. to sustain the plasma in cylindrical dielectric tube.
• Inductively coupled plasmas are known to have low coupling efficiency of the radio frequency energy into the plasma and a lower plasma temperature compared to arc and microwave generated plasmas.
• the magnetic field responsible for generating the plasma exhibits a non-uniform profile, which leads to a plasma with a large temperature gradient, where the plasma takes a donut-like shape that exhibiting the highest temperature at the edge of the plasma (close to the dielectric tube walls) and the lowest temperature in the center of the donut.
• metal powder particles should exhibit a spherical shape, which can be achieved through the process of spheroidization. This process involves the melting of particles in a hot environment whereby surface tension of the liquid metal shapes each particle into a spherical geometry, followed by cooling and re-solidification.
• spherical powders can be directly produced by various techniques.
• a plasma rotating electrode PRP
• PRP plasma rotating electrode
• gas atomization which uses a relatively complicated set up and may introduce porosity to the powder.
• Spheroidization methods of irregular shape powders include TEKNA’s (Sherbrook, Quebec, Canada) spheroidization process using inductively coupled plasma (ICP), where angular powder obtained from Hydride-Dehydride (HDH) process is entrained within a gas and injected through a hot plasma environment to melt the powder particles.
• ICP inductively coupled plasma
• HDH process involves several complex steps, including hydrogenation dehydrogenation, and deoxydation before the powder is submitted to spheroidization. This process is a time consuming multi-step process, which drives up the cost of metal powders made through these methods.
• a method for manufacturing a spheroidized powder from powder previously manufactured from a gas atomization process comprising introducing powder previously manufactured from a gas atomization process into a microwave plasma torch, the powder previously manufactured from a gas atomization process having an average particle size outside of a range for additive manufacturing, and melting and spheroidizing the powder previously manufactured from a gas atomization process within the microwave plasma torch to form spheroidized powder particles having different average particle sizes and a smaller particle size distribution from the average particles size and the particle size distribution of the powder previously manufactured from a gas atomization process.
• the melting and spheroidizing increases the average particle size.
• the melting and spheroidizing decreases the average particle size.
• the particle size distribution of the spheroidized particles is at least 50% less from 10% to 95% as compared to the particle size distribution of the powder previously manufactured from a gas atomization process.
• a 50 percentile particle size of the spheroidized powder is reduced by at least 40% as compared to a 50 percentile particle size of the powder previously manufactured from a gas atomization process.
• a 50 percentile particle size of the spheroidized powder is reduced by at least 50% as compared to a 50 percentile particle size of the powder previously manufactured from a gas atomization process.
• a 50 percentile particle size of the spheroidized powder is increased by at least 40% as compared to a 50 percentile particle size of the powder previously manufactured from a gas atomization process. In some embodiments, a 50 percentile particle size of the spheroidized powder is increased by at least 50% as compared to a 50 percentile particle size of the powder previously manufactured from a gas atomization process.
• the powder previously manufactured from a gas atomization process comprise a material selected from the group consisting of metal, metal alloy, titanium, titanium alloy, nickel, nickel alloy, cobalt, cobalt alloy, iron, iron alloy, a ductile metal, a ductile metal alloy, and ceramic.
• carbon and nitrogen are removed from the powder previously manufactured from a gas atomization process during the melting and spheroidizing.
• the spheroidized powder particles retain the same rheological properties as the powder previously manufactured from a gas atomization process after the melting and spheroidizing.
• a method for manufacturing a spheroidized powder from scrap metal or used metal parts comprising: providing scrap metal or used metal parts comprising a material selected from the group consisting of metal, metal alloy, titanium, titanium alloy, nickel, nickel alloy, cobalt, cobalt alloy, steel, and steel alloy; milling the scrap metal or used metal parts to produce metallic particles within a range of particle volumes pre-determined to be suitable for use as feedstock in a microwave plasma process; and applying the microwave plasma process to the metallic particles within the determined range of particle volumes to form spheroidized powder.
• the determined range of particle volumes can be between 15 and 63 microns.
• the scrap metal or used metal parts can comprise a work hardened microstructure that is retained in the spheroidized powder after applying the microwave plasma process. In some embodiments milling the scrap metal or used metal parts can be done without embrittling the scrap metal or used metal parts. [0016] In some embodiments, the scrap metal or used metal parts can comprise Ti 6Al-4V. In some embodiments the scrap metal or used metal parts can comprise alloy elements including Al, Mg, Ti, and/or Cu and, after applying the microwave plasma process the spheroidized powder still includes the Al, Mg, Ti, and/or Cu.
• the scrap metal or used metal parts can comprise sharp turnings, saw swarfs, grinding swarfs, grinding fines, and/or wash line fines. In some embodiments, the scrap metal or used metal parts can be selected for the milling to have a size and/or aspect ratio that will result post-milling in metallic particles within the pre-determined range of particle volumes.
• a method for manufacturing a spheroidized powder having a desired particle size distribution between about x and about y, wherein x represents a low end of the particle size distribution and y represents a high end of the particle size distribution comprising: introducing metallic particles obtained by milling or crushing scrap metal or used metal parts into a microwave plasma torch, a majority of said introduced metallic particles having a volume between about 4/3 ⁇ (x/2) 3 and about 4/3 ⁇ (y/2) 3 , and wherein said introduced metallic particles have a collective average or median aspect ratio between 2:1 and 200:1; and melting and spheroidizing the metallic particles within the microwave plasma torch to form spheroidized powder having the desired particle size distribution of about x to about y.
• x can equal 5 microns and y can equal 45 microns and the majority of said introduced metallic particles can have a volume between about 65.45 ⁇ m 3 and about 47,712.94 ⁇ m 3 .
• the collective average or median aspect ratio can be between 5:1 to 20:1. In some embodiments, the collective average or median aspect ratio can be between 10:1 to 100:1.
• the introducing metallic particles into the microwave plasma torch can comprise introducing the metallic particles into an exhaust of the microwave plasma torch or into a plume of the microwave plasma torch.
• a spheroidized a powder from used powder comprising: introducing previously used powder particles into a microwave plasma torch, the previously used powder particles comprising satellites, agglomerations, or contaminants; and melting and spheroidizing the previously used powder particles within the microwave plasma torch to form spheroidized powder particles having the agglomerations, contaminants, and satellites removed.
• the previously used powder particles can comprise satellites, agglomerations, and contaminants.
• the previously used powder particles can comprise a material selected from the group consisting of metal, metal alloy, titanium, titanium alloy, nickel, nickel alloy, cobalt, cobalt alloy, steel, steel alloy, a ductile metal, a ductile metal alloy, and ceramic.
• carbon and nitrogen can be removed from the previously used powder particles during the melting and spheroidizing.
• the previously used powder particles can be formed from an additive manufacturing process selected from the group consisting of laser sintering, electron-beam melting, filament fused deposition, directed energy deposition, powder bed fusion, and binder jetting.
• the spheroidized powder particles can retain the same rheological properties as the previously used powder particles after the melting and spheroidizing.
• a method for producing a spheroidized powder from a feed material comprising dehydrogenated or non-hydrogenated titanium or titanium alloy comprising: introducing a feed material comprising dehydrogenated or non-hydrogenated titanium or titanium alloy particles into a microwave plasma torch; and melting and spheroidizing the particles within a plasma generated by the microwave plasma torch to form spheroidized powder.
• the feed material can comprise titanium or titanium alloy particles processed by a hydrogenation-dehydrogenation (HDH) process.
• the spheroidized powder can comprise particles with a median sphericity of at least 0.75. In some embodiments, the spheroidized powder can have a particle size distribution of between 5 and 45 microns at a low end of the particle size distribution range and between 15 and 105 microns at a high end of the particle size distribution range. [0023] In some embodiments, one or more processing variables can be set to create a martensitic microstructure in the spheroidized particles. In some embodiments, one or more processing variables can be set to create an equiaxed microstructure in the spheroidized particles.
• one or more processing variables can be set to create at least two regions in the spheroidized powder, each region having a different microstructure.
• the at least two regions can include a core portion and a skin portion, the skin portion having a microstructure that can be different from a microstructure of the feed material.
• the feed material can have a particle size of no less than 1.0 microns and no more than 300 microns.
• the feed material can comprise Ti 6Al-4V.
• FIG. 2 illustrates an example embodiment of scrap metal feedstock in the form of metal turnings after microwave plasma processing according to the present disclosure.
• FIG.3 illustrates an example of a plot of L/W (aspect ratio) for a sample of metal turnings before microwave plasma processing according to the present disclosure.
• FIG. 4 illustrates an example embodiment of a method for reusing scrap metal/alloys using microwave plasma processing according to the present disclosure.
• FIG. 5 illustrates an example embodiment of a method for processing hydride-dehydride (HDH) produced feedstock using microwave plasma processing according to the present disclosure.
• FIG. 6 and FIG. 7 illustrate example embodiments of used powder CoCr feedstock before microwave plasma processing according to the present disclosure.
• FIG. 9 illustrate example embodiments of used powder CoCr feedstock after microwave plasma processing according to the present disclosure.
• FIG. 10 illustrates an example embodiment of a method of producing spheroidal particles according to the present disclosure.
• FIG.11 illustrates an embodiment of a microwave plasma torch that can be used in the production of spheroidal metal or metal alloy powders, according to embodiments of the present disclosure.
• FIGS.12A-B illustrate embodiments of a microwave plasma torch that can be used in the production of spheroidal metal or metal alloy powders, according to a side feeding hopper embodiment of the present disclosure.
• FIG.12A-B illustrate embodiments of a microwave plasma torch that can be used in the production of spheroidal metal or metal alloy powders, according to a side feeding hopper embodiment of the present disclosure.
• FIG. 13 illustrates an example embodiment of a method of producing titanium based (e.g., titanium, titanium alloy) spheroidal particles having a desired microstructure according to the present disclosure.
• FIG. 14 illustrates an example embodiment of a method of modifying a particle microstructure according to embodiments of the present disclosure.
• FIG. 15 illustrates an embodiment of a particle modified according to embodiments of the present disclosure.
• FIG. 16 illustrates an embodiment of a grain size calculation.
• FIG. 17 illustrates embodiments of microstructures.
• FIG.18 illustrates previously used powders (left) and spheroidized powders (right) according to embodiments of the disclosure.
• FIG. 19 illustrates oversized particles formed from gas atomization.
• FIG. 20 illustrates physical properties data on oversized particles formed from gas atomization
• FIG. 21 illustrates oversized gas atomized particles after performing embodiments of methods disclosed herein.
• FIG. 22 illustrates data on oversized gas atomized particles after performing embodiments of methods disclosed herein.
• FIG.23 illustrates microstructure changes for embodiments of the disclosed methods. DETAILED DESCRIPTION [0045] Disclosed herein are embodiments of methods, devices, and assemblies for spheroidization of feedstock materials using microwave plasma processing. Each different feedstock material has its own critical, specialized, and unique requirements for the initial feedstock as well as the processing in a microwave plasma torch in order to achieve a desired spheroidization.
• the feedstock materials disclosed herein pertain to scrap materials, dehydrogenated or non-hydrogenated feed material, recycled used powder, and powders previously manufactured by a gas atomization process, the feedstocks which may require initial pre-processing or specific plasma processing.
• processing in a microwave plasma torch can include feeding the feedstock into a microwave plasma torch, a plasma plume of the microwave plasma torch, and/or an exhaust of the microwave plasma torch.
• the location may vary depending on the type of feedstock used.
• the feedstock can be selected based on different requirements. Examples of requirements are aspect ratio, particle size distribution (PSD), chemistry, density, diameter, sphericity, oxygenation, hardness, and ductility.
• Scrap materials [0046] Disclosed herein are embodiments of methods, devices, and assemblies for reusing scrap metals/alloys and/or used parts made from metals/alloys (e.g., grave-to-cradle or scrap to premium).
• embodiments of the disclosure allow for taking metallic scrap or used metal parts, such as turnings, and without embrittling (such as through the use of hydrogenation or cryogenics) creating a feedstock for a microwave plasma process.
• scrap or used metal parts can be milled to a desired volume of particles of a feedstock or turnings, though in some embodiments may not be milled.
• the feedstock or turnings can then be used as a feedstock for a microwave plasma process to form a final spheroidized powder, which can then be used in different processes, such as additive manufacturing processes.
• scrap material is extremely difficult to process into a proper feedstock for microwave plasma processing.
• the method can include an analysis of the inter- relationship between 1) selection of feedstock size/aspect ratio, 2) a milling approach that breaks up ductile pieces without embrittling steps, and 3) a final desired particle volume, in order to create a desired particle size distribution for specific applications.
• the feedstock is embrittled before milling.
• the final specific application can be, for example, laser bed fusion which has a particle size distribution (PSD) of 15-45 microns (or about 15 to about 45 microns), or 15-63 microns (or about 15 to about 63 microns) or 20-63 microns (or about 20 – about 63 microns), electron beam processing which can have a particle size distribution of 45-105 microns (or about 45 to about 105 microns) or 105 – 150 microns (or about 105 to about 150 microns), or metal injection molding (MIM).
• PSD particle size distribution
• MIM metal injection molding
• the PSD can be expressed as the D50 of the particles in the feedstock.
• the feedstock is processed through jet milling, wet milling, or ball milling.
• the PSD of the feedstock is 15-15 microns, 15-45 microns, 20-63 microns, 45-105 microns, or 105 to 150 microns.
• the PSD can be adjusted depending on the powder processing technology such as laser powder bed fusion, direct energy deposition, binder jet printing, metal injection molding, and hot isostatic pressing.
• the original scrap or used metal parts can be sharp turnings (e.g., having high aspect ratio, high surface area, thin, or spaghetti-like material, scrap aggregator), saw swarf (high aspect ratio, thin material), grinding swarf (less aspect ratio powder like material), grinding fines, or wash line fines (less aspect ratio, thick or thin plate like material) which can then be broken up into a feedstock of a particular PSD, such as in a milling process, and then microwave plasma processing this feedstock into spherical and dense powders.
• the scrap can be 3D printed parts (such as failed 3D printed parts) or castings (such as failed castings).
• the input materials can be wash line fine, saw swarfs, grinding swarfs. In some embodiments, the input materials can be used or scrap parts by processes like but not limited to grinding, milling, cutting, or turning.
• FIG. 1 is an illustrative example of metal turning feedstock before plasma processing.
• FIG. 2 depicts the illustrative example of metal turnings after plasma processing.
• high aspect ratio turnings from machining processes are used as feedstock into the microwave plasma melting process to produce spherical powders.
• the average aspect ratio of the turnings is 2:1 (or about 2:1), 3:1 (or about 3:1), 5:1 (or about 5:1), 10:1 (or about 10:1), 20:1 (or about 20:1), 100:1 (or about 100:1), or 200:1 (or about 200:1). In some embodiments, the average aspect ratio of the turnings is greater than 1:1 (or about 1:1), 3:1 (or about 3:1), 5:1 (or about 5:1), greater 10:1 (or about 10:1), greater 20:1 (or about 20:1), greater 100:1 (or about 100:1), or greater 200:1 (or about 200:1).
• the average aspect ratio of the turnings is less than, 3:1 (or about 3:1), 5:1 (or about 5:1), greater 10:1 (or about 10:1), greater 20:1 (or about 20:1), greater 100:1 (or about 100:1), or greater 200:1 (or about 200:1).
• the aspect ratio of a majority of the turnings is 2:1 (or about 2:1), 3:1 (or about 3:1), 5:1 (or about 5:1), 10:1 (or about 10:1), 20:1 (or about 20:1), 100:1 (or about 100:1), or 200:1 (or about 200:1).
• the aspect ratio of a majority of the turnings is greater than 1:1 (or about 1:1), 3:1 (or about 3:1), 5:1 (or about 5:1), greater 10:1 (or about 10:1), greater 20:1 (or about 20:1), greater 100:1 (or about 100:1), or greater 200:1 (or about 200:1). In some embodiments, the aspect ratio of a majority of the turnings is less than, 3:1 (or about 3:1), 5:1 (or about 5:1), greater 10:1 (or about 10:1), greater 20:1 (or about 20:1), greater 100:1 (or about 100:1), or greater 200:1 (or about 200:1).
• the aspect ratio of greater than 75% of the turnings is 2:1 (or about 2:1), 3:1 (or about 3:1), 5:1 (or about 5:1), 10:1 (or about 10:1), 20:1 (or about 20:1), 100:1 (or about 100:1), or 200:1 (or about 200:1). In some embodiments, the aspect ratio of greater than 75% of the turnings is greater than 1:1 (or about 1:1), 3:1 (or about 3:1), 5:1 (or about 5:1), greater 10:1 (or about 10:1), greater 20:1 (or about 20:1), greater 100:1 (or about 100:1), or greater 200:1 (or about 200:1).
• the aspect ratio of greater than 75% of the turnings is less than, 3:1 (or about 3:1), 5:1 (or about 5:1), greater 10:1 (or about 10:1), greater 20:1 (or about 20:1), greater 100:1 (or about 100:1), or greater 200:1 (or about 200:1).
• the aspect ratio of greater than 90% of the turnings is 2:1 (or about 2:1), 3:1 (or about 3:1), 5:1 (or about 5:1), 10:1 (or about 10:1), 20:1 (or about 20:1), 100:1 (or about 100:1), or 200:1 (or about 200:1).
• the aspect ratio of greater than 90% of the turnings is greater than 1:1 (or about 1:1), 3:1 (or about 3:1), 5:1 (or about 5:1), greater 10:1 (or about 10:1), greater 20:1 (or about 20:1), greater 100:1 (or about 100:1), or greater 200:1 (or about 200:1). In some embodiments, the aspect ratio of greater than 90% of the turnings is less than, 3:1 (or about 3:1), 5:1 (or about 5:1), greater 10:1 (or about 10:1), greater 20:1 (or about 20:1), greater 100:1 (or about 100:1), or greater 200:1 (or about 200:1).
• the feedstock is tailored to have a volume distribution approximately equal to the volume distribution of the desired PSD of processed powder. Volume is calculated based on 4/3* ⁇ *r 3 where ‘r’ is the radius of the processed powder.
• a majority of the feedstock particles have a volume within a range of about 4/3 ⁇ (x/2) 3 and about 4/3 ⁇ (y/2) 3 , wherein x is the low end of the desired particle size distribution and y is the high end of the desired particle size distribution.
• substantially all of the feedstock particles have a volume within a range of about 4/3 ⁇ (x/2) 3 and 4/3 ⁇ (y/2) 3 .
• the volume distribution of the preprocessed and processed feedstock can be between about 65.45 ⁇ m 3 and about 47,712.94 ⁇ m 3 , corresponding to a desired particle size distribution of 5 to 45 microns for the processed powder
• an average or median aspect ratio, collectively, of preprocessed feedstock can be between 2:1 and 200:1, between 3:1 and 200:1, between 4:1 and 200:1, or between 5:1 and 200:1.
• any of the disclosed ratios/diameters can be used for the volume calculation.
• the particle size distribution in one example can be 5 to 45 microns.
• particle size distributions are also contemplated, including but not limited to particle size distributions of between 5 and 45 microns at a low end of the particle size distribution range and between 15 and 105 microns at a high end of the particle size distribution range (e.g., 5 to 15 microns, 15 to 45 microns, 45 to 105 microns).
• the volume distribution of the feedstock can be the same as the final spheroidized powder.
• the overall volume of the feedstock can be the generally the same as the final spheroidized powder.
• the overall volume of the feedstock can be within 1%, 2%, 3%, 4%, 5%, 10%, 15%, or 20% (or about 1%, about 2%, about 3%, about 4%, about 5%, about 10%, about 15%, or about 20%) of the final spheroidized powder.
• the feedstock may be generally spherical, or generally non-spherical.
• the feedstock can be misshapen feedstock, cubes, filaments, wires, etc.
• FIG.3 is an illustrative example of a sample of high aspect ratio turnings.
• L/W (aspect ratio) is plotted for every individual particle in a sample of high aspect ratio turnings. Aspect ratio is shown as L/W. As can be seen, the aspect ratios range from around 1:1 to 15:1 with most of the particles falling between 1:1 to 7:1. However, this is merely one example, and other aspect ratios can be used as well.
• Turnings from machining processes can be first collected, cleaned from the machining oils and other impurities, and then sieved to separate small particles/turnings that can directly be used as feedstock from larges ones that need further processing to reduce their size. An example method for further reducing the size of the turnings to the desired sizes is through milling.
• the scrap may be pre-processed before they are introduced into the plasma process.
• the scrap may be sieved to remove large agglomerations and selected to the desired size to be processed in the plasma.
• the scrap may be cleaned with water, surfactant, detergent, solvent or any other chemical such as acids to remove contamination.
• the scrap may be magnetically cleaned if they are contaminated with any magnetic material.
• the cleaning removes contaminants such as ceramics and oils.
• the scrap can be pre-treated to de-oxidize it.
• other elements or compounds can be added to compensate or modify the chemistry of the used parts.
• the scrap can be de-dusted to remove fines.
• no pre-processing may be performed. All of these pre-processing techniques can also be used on the post-milled scrap feedstock.
• the material to be milled can be titanium or titanium alloys.
• titanium is commercially pure titanium (CpTi) (known as CpTi), TiAl, Ti-6Al-4V (Ti-6-4), and the particular titanium material/alloy does not limit the disclosure.
• CpTi commercially pure titanium
• TiAl Ti-6Al-4V
• Ti-6-4 titanium material/alloy
• Titanium can be particular problematic for milling as it is highly ductile, and thus would merely bend or change shape, and would not be broken down properly into a powder without embrittling, such as through hydrogenation or cryogenics.
• embodiments of the disclosure can mill titanium or titanium alloys without such an embrittling process. This can be done through the understanding and proper selection of the scrap material to be milled, such as by only choosing material having a particular volume/size/aspect ratio.
• FIG.4 is an illustrative example of a flow chart of a process 100 for reusing scrap metal/alloys.
• the metal/alloy scraps can be received.
• the metal/alloy scraps can be turnings, wash line fine, saw swarfs, grinding swarfs.
• the scrap metal/alloys can be used or scrap parts by processes like but not limited to grinding, milling, cutting, or turning.
• the metal/alloy scraps can be cleaned.
• the cleaning is with water, surfactant, detergent, solvent or any other chemical such as acids to remove contamination.
• the cleaning removes machining oils and other impurities.
• the metal/alloy scraps can be sieved in order to sort between pieces that are too large and pieces that are small enough to be used as feedstock. If the pieces are small enough to be used as feedstock they can pass to block 112. If the pieces are too large, they can be milled at block 110 into smaller scrap metal/alloys in order to adjust particle size. In some embodiments, the milling can be jet milling, wet milling, and/or ball milling. Block 106 can be repeated in order to additionally sieve the milled scrap metal/alloys. Alternatively, it can be decided that the milled scrap metal/alloys are ready to be used as feedstock at block 112.
• the milled scrap metal/alloy that is ready to use as feedstock can be microwave plasma processed. Microwave plasma processing is described below and is also shown in FIG. 11 and FIGS. 12A-B. [0064] As discussed above, scrap material may be extremely complicated to prepare for a feedstock. Dehydrogenated or Non-Hydrogenated Feed Material [0065]
• One aspect of the present disclosure involves a process of spheroidization of metals and metal alloy using a microwave generated plasma. The process uses readily available existing pre-screened or non-prescreened raw materials made of metal and/or metal alloys as feedstock.
• the powder feedstock is entrained in inert and/or reducing and/or oxidizing gas environment and injected into the microwave plasma environment.
• the feedstock Upon injection into a hot plasma, the feedstock is spheroidized and released into a chamber filled with an inert gas and directed into hermetically sealed drums where is it stored.
• This process can be carried out at atmospheric pressure, in a partial vacuum, or at a slightly higher pressure than atmospheric pressure. In alternative embodiments, the process can be carried out in a low, medium, or high vacuum environment. The process can run continuously and the drums are replaced as they fill up with spheroidized metal or metal alloy particles.
• a hydride-dehydride (HDH) process can be used to resize large metallic or metallic alloy pieces down to a finer particle size distribution through crushing, milling, and screening.
• Metal and alloy powders can be manufactured using the HDH process, where bulk feedstock, such as coarse metal powders or metal/metal alloy scraps, etc., are heated in a hydrogen-containing atmosphere at high temperature ( ⁇ 700 °C) for a few days. This leads to the formation of a brittle metal hydride, which can readily be crushed into a fine power and sifted to yield a desired size distribution determined by the end user.
• hydrogen must be dissociated and removed from the metal by heating the metal hydride powder within vacuum for a period of time. The dehydrogenated powder must then be sifted to remove large particle agglomerations generated during process due to sintering.
• Embodiments of the disclosed HDH processes are primarily carried out as solid-state batch processes.
• a volume of metal powder can be loaded into a crucible(s) within a vacuum furnace. The furnace can be pumped down to a partial vacuum and is repeatedly purged with inert gas to eliminate the presence of undesired oxygen.
• Dehydrogenation is rapid on the particle surface where H2 can readily leave the particles. However, within the bulk of the powder, H2 must diffuse through the bulk of the solid before it reaches surface and leave the particle. Diffusion through the bulk is a rate-limiting process “bottle-neck” requiring relatively long reaction time for complete dehydrogenation. The time and processing temperatures required for dehydrogenation are sufficient to cause sintering between particles, which results in the formation of large particle agglomerations in the final product. Post-process sifting can eliminate the agglomerations. Before the powder can be removed from the furnace, it can be sufficiently cooled to maintain safety and limit contamination. The thermal mass of the large furnaces may take minutes or hours to sufficiently cool.
• FIG. 5 illustrates an embodiment of producing spheroidized titanium powder (200) from an HDH feed.
• the process flow (201) on the left of FIG. 5 presents an example process that combines a HDH process (200) with spheroidization of titanium powders. The process starts with Ti raw material (step a, 205) that is hydrogenated (step b, 210), and then crushed and sifted to size (step c, 215).
• Pure titanium is recovered through dehydrogenation (step d, 220). It is then screened for agglomerations and impurities, and then sifted to the size specified by the customer (step e, 225). The powder then goes through a deoxidation step to reduce or eliminate oxygen that it picked up during the sifting and screening processes. Deoxidation is useful especially for small particle sizes, such as particles below 50 microns, where the surface to volume ratio is substantial (step f, 230). The titanium particles are then spheroidized (step g, 235) and collected (step h, 240). A similar process can be used to create a Ti alloy, such as Ti 6-4, instead of pure titanium powder.
• the powder is entrained within an inert gas and injected into a microwave generated plasma environment (235) exhibiting a substantially uniform temperature profile between approximately 4,000 K and 8,000 K and under a partial vacuum.
• the hermetically sealed chamber process can also run at atmospheric pressure or slightly above atmospheric pressure to eliminate any possibility for atmospheric oxygen to leak into the process.
• the particles are melted in the plasma, spheroidized due to liquid surface tension, re-solidifying after exiting the plasma.
• the particles are then collected in sealed drums in an inert atmosphere (140).
• M an arbitrary metal:
• dissociation of hydrogen from the metal to form hydrogen gas is favored, driving the above reaction to the right.
• the rate of dissociation of hydrogen from the liquid metal is rapid, due to convection, which continually introduces H 2 to the liquid surface where it can rapidly leave the particle.
• feedstock sizing can be difficult to obtain.
• An HDH process can aid in the process of obtaining feedstock that meets certain size criteria.
• the previously used powders can be powders which have already undergone a manufacturing process, such as an additive manufacturing process.
• the previously used powders were previously manufactured powders that are outside of the acceptable sizing of powders for particular processes, such as additive manufacturing.
• embodiments of the disclosure allow for the taking of used powder and converting it into a feedstock for a microwave plasma process to form a final spheroidized powder, which can then be used in different processes, such as additive manufacturing processes, metal injection molding (MIM), or hot isostatic Pressing (HIP) processes.
• MIM metal injection molding
• HIP hot isostatic Pressing
• This can be especially useful for powders that were manufactured using a gas atomized process, which can create excessively large particles.
• large and/or misshapen particles can be re-spheroidized.
• Used powder can be of differing quality and therefore it can be challenging to make use of used powder as feedstock.
• the feedstock can be contaminated or an incorrect size, or altogether difficult to process.
• the powders may be pre-processed before they are introduced into the plasma process.
• the powders may be sieved to remove large agglomerations and selected the desired size to be processed in the plasma.
• the powders may be cleaned with water, surfactant, detergent, solvent or any other chemical such as acids to remove contamination.
• the powders may be magnetically cleaned if they are contaminated with any magnetic material.
• the powder can be pre-treated to de-oxidize it.
• other elements or compounds can be added to compensate or modify the chemistry of the powder.
• the powder can be de-dusted to remove fines. In some embodiments, no pre-processing may be performed.
• the previously used powder can be modified to make it more applicable as the feedstock as the previous processing can make the powder/particles unusable.
• “satellites”, which can hurt/reduce flow can be removed.
• used powder can become agglomerated, and the disclosed process can separate the particles in the powder.
• contaminants, such as organics can be removed.
• carbon, nitrogen, oxygen, and hydrogen can be removed from the previously used powder by the disclosed process.
• artifacts can be removed.
• the disclosed process can also improve the flowability of the used powders.
• surface texture can be adjusted to reduce surface roughness of used powder to improve flowability.
• flowability can be improved by absorbing satellites.
• residence time and power levels can be modified to absorb satellites or evaporate them, such as with minimal affect the chemistry of the bulk powders.
• embodiments of the disclosed methods can make the used powered spherical again, for example a powder having particles that were spherical and have become not spherical during a previous process. These previous processes can include, but are not limited to, gas atomization, laser bed fusion, electron-beam melting, and binder jetting.
• the used powder can be larger powder waste from an electron beam process, which can then be made into a smaller powder for laser application.
• the used powder can be larger powder waste from a gas atomization process, which can then be made into a smaller powder for laser application.
• the powder after use, has agglomerations, increased oxygen content that is out of specification, contamination from soot and inorganic materials, and/or deformation which makes them non- spherical. In these embodiments, the powders cannot be reused without processing.
• PSD is with a minimum diameter of 1 micrometers ( ⁇ m) and a maximum diameter of 22 ⁇ m, or a minimum of 5 ⁇ m and a maximum of 15 ⁇ m, or a minimum of 15 ⁇ m and a maximum of 45 ⁇ m or a minimum of 22 ⁇ m and a maximum of 44 ⁇ m, or a minimum of 20 ⁇ m to a maximum of 63 ⁇ m, or a minimum of 44 ⁇ m and a maximum of 70 ⁇ m, or a minimum of 70 ⁇ m and a maximum of 106 ⁇ m, or a minimum of 105 ⁇ m to a maximum of 150 ⁇ m, or a minimum of 106 ⁇ m and a maximum of 300 ⁇ m.
• the disclosed processing methods retains alloy elements especially highly volatile elements such as Al, Mg, Ti, and Cu from the used powder.
• This disclosure describes the rejuvenation of used powders described above to produce fresh powders with improved specifications.
• the microwave plasma process that is made of a microwave generated plasma is used to rejuvenate used powders described above to better specifications, so they can be used again as feedstock to the powder metallurgy processes described above.
• FIG. 18 illustrates previously used powders 1802 (left) as compared to spheroidized powders 1804 (right).
• the particle size distribution can be maintained.
• the particle size distribution can be improved/tightened by absorbing satellites.
• the particle size distribution can be improved/tightened by re-spheroidizing large agglomerates.
• used powder can include a) 5% by weight of satellites that are absorbed or evaporated by the microwave plasma process, and b) large misshapen agglomerations, both of which can be removed by embodiments of the disclosed process.
• powders having a particle size distribution of 45-106 micron can be reduced to 15-45 micron, such as for laser powder bed.
• the particle size distribution can be the D50 of the particles in the powder.
• the particle size diameter can be altered. In some embodiments, the particle size diameter can be reduced. In some embodiments, the particle size diameter can be reduced to produce smaller diameter particle size by partially vaporizing the surface of large particles. For example, powder from an e-beam powder bed with 45-106 micron particle size diameter can be used to produce powder with 15-45 micron particle size to be used in a laser bed additive manufacturing process.
• FIG. 19 illustrates powders formed from a gas atomization (GA) process shown at 100X magnification at 1902 and 1000X magnification at 1904.
• G gas atomization
• the illustrated powders may have an apparent density of about 2.483 g/cc, no Hall Flow, and a composition comprising about 0.106 oxygen wt% and about 0.016 nitrogen wt%.
• FIG. 20 illustrates a particle size distribution chart for the powders of FIG. 19.
• FIG. 21 illustrates powders formed from embodiments of the disclosure shown at 100X magnification at 2102 and 1000X magnification at 2104.
• the powder illustrated in FIG. 21 may comprise a composition comprising about 0.076 oxygen wt% and about 0.011 nitrogen wt%.
• FIG. 22 illustrates a particle size distribution chart for the powders of FIG. 21.
• the gas atomization process typically produces wide range of particle sizes, too fine or too coarse on average, are otherwise unusable.
• embodiments of the disclosure can convert the unusably sized particles to particle sizes, which can be used in different processes, such as additive manufacturing processes.
• the methods disclosed herein can greatly tighten the particle size distribution, while also reducing the overall size of the powders. For example, the 50 percentile of particles are around 34 microns, whereas the powder originally had a 50 percentile of particles are 52 microns. Thus, the average particle size can be reduced (or increased if needed in other embodiments) Further, the overall powder distribution has been narrowed, where the original particles spanned from 21-101 microns (from 10% to 95%), whereas after processing the particles span from 23 to 58 microns (from 10% to 95%).
• the 50 percentile of particle sizes can be reduced by 10, 20, 30, 40, 50, 60, or 70% (or about 10, about 20, about 30, about 40, about 50, about 60, or about 70%). In some embodiments, the 50 percentile of particle sizes can be reduced by greater than 10, 20, 30, 40, 50, 60, or 70% (or about 10, about 20, about 30, about 40, about 50, about 60, or about 70%). In some embodiments, the 50 percentile of particle sizes can be reduced by less than 10, 20, 30, 40, 50, 60, or 70% (or about 10, about 20, about 30, about 40, about 50, about 60, or about 70%).
• the particle size distribution from 10% to 95% can be reduced by 10, 20, 30, 40, 50, 60, or 70% (or about 10, about 20, about 30, about 40, about 50, about 60, or about 70%). In some embodiments, the particle size distribution from 10% to 95% can be reduced by greater than 10, 20, 30, 40, 50, 60, or 70% (or about 10, about 20, about 30, about 40, about 50, about 60, or about 70%). In some embodiments, the particle size distribution from 10% to 95% can be reduced by less than 10, 20, 30, 40, 50, 60, or 70% (or about 10, about 20, about 30, about 40, about 50, about 60, or about 70%).
• the 50 percentile of particle sizes can be increased by 10, 20, 30, 40, 50, 60, or 70% (or about 10, about 20, about 30, about 40, about 50, about 60, or about 70%). In some embodiments, the 50 percentile of particle sizes can be increased by greater than 10, 20, 30, 40, 50, 60, or 70% (or about 10, about 20, about 30, about 40, about 50, about 60, or about 70%).
• the 50 percentile of particle sizes can be increased by less than 10, 20, 30, 40, 50, 60, or 70% (or about 10, about 20, about 30, about 40, about 50, about 60, or about 70%).
• the plasma gases can be specific to the materials of the powders.
• nitrogen gas can be used in the case of metal and metal alloys that do not readily form nitrides.
• One example is the processing of Inconel 718 where when it is run in a nitrogen plasma environment, the processed powder is not chemically altered and do not present any nitrogen incorporation into the bulk powder.
• noble gases such as argon, argon/helium mixture can be used.
• noble gases can be mixed with hydrogen gas to increase the uniformity of the plasma.
• An example of a metal alloy that is susceptible to reaction with nitrogen is titanium alloy Ti 6%Al - 4%V (by weight).
• noble gases and mixtures such as argon a and argon/hydrogen mixtures are used to avoid any reaction between the powders and the plasma gases.
• nitrogen can be used when the processed powder is not reactive with the above mentioned gas.
• the reconditioning of the used powder/particles can include the removal of artifacts, such as from a laser sintering process. Further, satellites and agglomerated materials due to overheating, for example from a laser process outside a build line, can be removed.
• the particular process to form the used particles is not limiting and other processes could have been performed on the original particles.
• the reconditioning of the used powder/particles can allow the powder/particles to, in some embodiments, regain their original rheological properties (such as bulk density, flowability, etc.).
• the reconditioning of used powder/particles can also improve the rheological properties. This can be achieved through the removing of any satellite on the surface through surface melting of the satellites and their incorporation into the bulk of the particle. In some cases, full melting of the particles will densify particles and remove any porosity.
• FIG.6 and FIG.7 illustrates a sample of CoCr which includes satellites before processing.
• FIG. 8 and FIG. 9 illustrates a sample of CoCr after microwave plasma processing in which satellites are removed which can improve flowability by 25% (or by about 25%).
• FIG. 6 and FIG. 8 show the same powder before and after microwave plasma processing, respectively.
• FIG.7 and FIG.9 show the same powder before and after microwave plasma processing, respectively.
• satellites can be absorbed into larger particles.
• a satellite can be a main powder particle that has a size that is within the defined particle size distribution to which a small particle of much smaller diameter that is outside the particle size distribution than the diameter of the main particle is agglomerated either through sintering or other physical processes.
• An agglomeration can be two or more particles which coalesce to form a larger particle.
• the reconditioning can minimize oxygen pickup during the reconditioning. This can be achieved by, for example, adding hydrogen or reducing agent, running in a close environment, or running at a high temperature. In some embodiments, atmospheric pressure inert gas can be used. In some embodiments, a low oxygen environment can be used.
• the alloying component chemistry or minor component chemistry may not be altered. In some embodiments, certain elements with low melting temperatures can be removed from the powder.
• the previously used powder particles can be metal or metal alloys. In some embodiments, the previously used powder particles can be titanium or titanium alloys. Specific titanium that can be used is Ti (known as CpTi), TiAl, Ti-6-4, and the particular titanium material/alloy does not limit the disclosure. Other materials can be used as well, for example other ductile materials. In some embodiments, nickel and nickel alloys, cobalt, and cobalt alloys, steel, or stainless steel can be the previously used powder particles and the particular material is not limiting.
• nickel metals/alloys such as Iconel 718 and 625 superalloys
• YSZ, MY, CoO, Al 2 O 3 - TiO2, Stainless 316L, and 17-4 can be used.
• used powder may be extremely complicated to prepare for a feedstock.
• Sphericity the final particles achieved by the plasma processing can be spherical or spheroidal, terms which can be used interchangeably.
• all of the feedstocks can be transformed into the spherical powders.
• Embodiments of the present disclosure are directed to producing particles that are substantially spherical or spheroidal or have undergone significant spheroidization.
• spherical, spheroidal or spheroidized particles refer to particles having a sphericity greater than a certain threshold.
• particles can have a sphericity of greater than 0.5, 0.6, 0.7, 0.75, 0.8, 0.9, 0.91, 0.95, or 0.99 (or greater than about 0.5, about 0.6, about 0.7, about 0.75, about 0.8, about 0.8, about 0.91, about 0.95, or about 0.99).
• particles can have a sphericity of 0.75 or greater or 0.91 or greater (or about 0.75 or greater or about 0.91 or greater). In some embodiments, particles can have a sphericity of less than 0.5, 0.6, 0.7, 0.75, 0.8, 0.9, 0.91, 0.95, or 0.99 (or less than about 0.5, about 0.6, about 0.7, about 0.75, about 0.8, about 0.8, about 0.91, about 0.95, or about 0.99).
• a particle is considered to be spherical, spheroidal or spheroidized if it has a sphericity at or above any of the aforementioned sphericity values, and in some preferred embodiments, a particle is considered to be spherical if its sphericity is at or about 0.75 or greater or at or about 0.91 or greater.
• a median sphericity of all particles within a given powder can be greater than 0.5, 0.6, 0.7, 0.75, 0.8, 0.9, 0.91, 0.95, or 0.99 (or greater than about 0.5, about 0.6, about 0.7, about 0.75, about 0.8, about 0.8, about 0.91, about 0.95, or about 0.99). In some embodiments, a median sphericity of all particles within a given powder can be less than 0.5, 0.6, 0.7, 0.75, 0.8, 0.9, 0.91, 0.95, or 0.99 (or less than about 0.5, about 0.6, about 0.7, about 0.75, about 0.8, about 0.8, about 0.91, about 0.95, or about 0.99).
• a powder is considered to be spheroidized if all or a threshold percentage (as described by any of the fractions below) of the particles measured for the given powder have a median sphericity greater than or equal to any of the aforementioned sphericity values, and in some preferred embodiments, a powder is considered to be spheroidized if all or a threshold percentage of the particles have a median sphericity at or about 0.75 or greater or at or about 0.91 or greater.
• the fraction of particles within a powder that can be above a given sphericity threshold can be greater than 50%, 60%, 70%, 80%, 90%, 95%, or 99% (or greater than about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 99%). In some embodiments, the fraction of particles within a powder that can be above a given sphericity threshold, such as described above, can be less than 50%, 60%, 70%, 80%, 90%, 95%, or 99% (or less than about 50%, about 60%, about 70%, about 80%, about 90%, about 95%, or about 99%).
• Particle size distribution and sphericity may be determined by any suitable known technique such as by SEM, optical microscopy, dynamic light scattering, laser diffraction, manual measurement of dimensions using an image analysis software, for example from about 15-30 measures per image over at least three images of the same material section or sample, and any other techniques.
• SEM SEM
• optical microscopy optical microscopy
• dynamic light scattering laser diffraction
• manual measurement of dimensions using an image analysis software, for example from about 15-30 measures per image over at least three images of the same material section or sample, and any other techniques.
• image analysis software for example from about 15-30 measures per image over at least three images of the same material section or sample, and any other techniques.
• bad particles only problematic particles
• the problematic particles can be separated from particles that could be used as a feedstock for the microwave plasma process without any further processing (“good particles”).
• good particles both the good and the bad particles can be put into the process.
• Powder metallurgy processes such as additive manufacturing, thermal and cold spray coating produce
• those powders’ morphology is changed from the original fresh powders and can include satellites, partial melting and/or other contaminants. Those changes can lead to a deterioration of the powder flowability, tap and bulk density, and sometime contamination such as carbon and nitrogen, and render the used powders useless for the same processes. Recycling those used powders to their original specifications can provide an economical advantage and lower costs.
• the used parts may be pre- processed before they are introduced into the plasma process. For example, the used parts may be sieved to remove large agglomerations and selected to the desired size to be processed in the plasma. In some embodiments, the used parts may be cleaned with water, surfactant, detergent, solvent or any other chemical such as acids to remove contamination.
• the used parts may be magnetically cleaned if they are contaminated with any magnetic material.
• the used parts can be pre-treated to de-oxidize it.
• other elements or compounds can be added to compensate or modify the chemistry of the used parts.
• the used parts can be de-dusted to remove fines.
• no pre-processing may be performed. All of these pre-processing techniques can also be used on the post-milled powder.
• the material to be milled can be titanium or titanium alloys. Specific titanium that can be used is Ti (known as CpTi), TiAl, Ti-6-4, and the particular titanium material/alloy does not limit the disclosure.
• Titanium can be particular problematic for milling as it is highly ductile, and thus would merely bend or change shape, and would not be broken down properly into a powder without embrittling, such as through hydrogenation or cryogenics.
• embodiments of the disclosure can mill titanium or titanium alloys without such an embrittling process. This can be done through the understanding and proper selection of the scrap material to be milled, such as by only choosing material having a particular volume/size/aspect ratio.
• Other materials can be used as well, for example other ductile materials.
• nickel and nickel alloys, steel, stainless steel, copper, copper alloys, and Hastealloy can be used and the particular material is not limiting.
• nickel metals/alloys such as Iconel 718 and 625 superalloys
• oxygen content of the material needs to be in the range of a few ppm to about 2% in the case of reactive materials and a few ppm to about 1% for non-reactive materials.
• the materials can come into the milling procedure having particular advantageous properties, such as a work-hardened microstructure.
• Embodiments of the disclosure allow for the work-hardened microstructure to last all the way through the microwave plasma processing, thereby forming a final spheroidized powder product retaining the work-hardened material.
• a Scherrer Equation can be used to calculate grain sizes using a full width half maximum (FWHM). This can show how at least a partial retention of microstructure is achieved from the original microstructure of the feedstock to the post plasma processing microstructure for any of the above processes, such as the recycling of gas atomized powders, the recycling of used powders, or the grave-to-cradle process.
• FWHM full width half maximum
• FIG. 17 illustrates different grain structures pre and post processing. As shown, the grain size of the particles can be significantly reduced to the nanoscale after spheroidization.
• GA powder 1702 comprises visible micro-sized grains.
• the ball-milled feedstock 1704 may comprise a nanoscale structure such that micro-scale grains are not visible.
• the plasma processed spheroidized powder 1706 may comprise a nanoscale structure such that micro-scale grains are not visible.
• FIG. 23 illustrates how plasma processing can improve microstructure, such as homogenizing and reducing/eliminating dendritic structure (top) between structure 2302 and structure 2304 or reducing precipitates (bottom) between structure 2306 and structure 2308.
• work hardened (or other microstructure) metals and metal alloys feedstock can be spheroidized without affecting the microstructure by a high heating rate that will only melt the surface of the particles without affecting the bulk, hence preserving the microstructure.
• the feedstock materials can be turnings that have been hardened during the machining process, or large scrap pieces made of hardened material and that is milled to the desired size to be used as feedstock for the spheroidization process.
• a miller can determine the thickness of materials that can be milled based on the prescribed desired volume.
• a user can perform the selection of pieces of ductile material that can be milled to a desired volume without embrittling the material, and then milling the material without having to embrittle first to produce particles each having the desired volume as feed material for the microwave plasma torch.
• scrap material made of ductile metals and/or metal alloys is milled in a process to avoid the material hardening.
• the ductile product of the milling process is then sieved to different size distributions to be used as feedstock for spheroidization in the microwave plasma melting process.
• the heating and cooling rates can be controlled through the residence time of the particles in the plasma and in the plasma afterglow.
• Embodiments of the disclosed process can include feeding the powders using a powder feeder into a microwave generated plasma where the power density, gas flows and residence time are controlled.
• the process parameters such as power density, flow rates and residence time of the powder in the plasma can depend on the powder material’s physical characteristics, such as the melting point and thermal conductivity.
• the power density can range from 20 W/cm 3 to 500 W/cm 3 (or about 20 W/cm 3 to about 500 W/cm 3 ).
• the total gas flows can range from 0.1 cfm to 50 cfm (or about 0.1 cfm to about 50 cfm), and the residence time can be tuned from 1 ms to 10 sec (or about 1 ms to about 10 sec).
• the scrap material can be material that is direct from the factory floor.
• any remaining contaminants such as oils, grease, or other material, can be removed before or during the disclosed process (either prior to milling, during milling, or during the microwave plasma melting).
• the ability to control oxygen can provide advantages, for example in the case of titanium scrap.
• the milling can be done in water. Thus, as the titanium is sheared apart fresh titanium surfaces oxidize, which increases the oxygen level.
• Different environmental gasses can be used for different applications.
• nitrogen gas can be used.
• One example is the processing of Inconel 718 where when it is run in a nitrogen plasma environment, the processed powder is not chemically altered and do not present any nitrogen incorporation into the bulk powder.
• the feedstock could be of various morphology such as angular powder, angular chips, irregular powder, and sponge powders.
• the feedstock can be processed to meet certain criteria for size, gas content, purity contamination and chemistry by processing such as but not limited to grinding, milling, cleaning, washing, drying and screening.
• the cleaning includes removing organic, ceramic, or other metallic contaminants.
• nickel or nickel alloys, steel or steel alloys, cobalt or cobalt alloys, and titanium or titanium alloys can be used in embodiments of the disclosure, and the particular material is not limiting.
• ceramics can be used.
• noble gases such as argon, argon/helium mixture can be used. Also these noble gases can be mixed with hydrogen gas to increase the uniformity of the plasma.
• An example of a metal alloy that is susceptible to reaction with nitrogen is titanium alloy Ti 6%Al - 4%V (by weight).
• Microwave Plasma Processing [0125] The process parameters can be optimized to obtain maximum spheroidization depending on the feedstock initial condition.
• U.S. Pat. Pub. No. 2018/0297122, US 8748785 B2, and US 9932673 B2 disclose certain processing techniques that can be used in the disclosed process, specifically for microwave plasma processing. Accordingly, U.S. Pat. Pub. No. 2018/0297122, US 8748785 B2, and US 9932673 B2 are incorporated by reference in its entirety and the techniques describes should be considered to be applicable to the feedstock described herein.
• One aspect of the present disclosure involves a process of spheroidization of metals and metal alloys using a microwave generated plasma.
• the powder feedstock is entrained in an inert and/or reducing gas environment and injected into the microwave plasma environment.
• the feedstock Upon injection into a hot plasma (or plasma plume or exhaust), the feedstock is spheroidized and released into a chamber filled with an inert gas and directed into hermetically sealed drums where is it stored.
• This process can be carried out at atmospheric pressure, in a partial vacuum, or at a slightly higher pressure than atmospheric pressure. In alternative embodiments, the process can be carried out in a low, medium, or high vacuum environment. The process can run continuously and the drums are replaced as they fill up with spheroidized metal or metal alloy particles.
• the rate of cooling of the spheroidized metal and metal alloys can be controlled to strategically influence the microstructure of the powder. For example, rapid cooling of ⁇ -phase titanium alloys facilitates an acicular (martensite) structure.
• Moderate cooling rates produce a Widman Berryn microstructure, and slow cooling rates form an equiaxed microstructure.
• microstructure of the metal and metal alloys can be controlled.
• the precise cooling rates required to form these structures is largely a function of the type and quantity of the alloying elements within the material.
• the rate of cooling especially when combined with the consistent and uniform heating capabilities of a microwave plasma plume, allow for control over the final microstructure.
• the above methods can be applied to processing metal (e.g., titanium and titanium alloys such as Ti 6-4) feedstock.
• metal e.g., titanium and titanium alloys such as Ti 6-4
• the control over microstructure is not limited thereto.
• the method and powders created by the present technology include the use of non- hydrided sources.
• titanium metal and various titanium metal alloys can be utilized as the feedstock source. These materials can be crushed or milled to create particles for treatment within a microwave plasma torch.
• Cooling processing parameters include, but are not limited to, cooling gas flow rate, residence time of the spheroidized particles in the hot zone, and the composition or make of the cooling gas.
• the cooling rate or quenching rate of the particles can be increased by increasing the rate of flow of the cooling gas. The faster the cooling gas is flowed past the spheroidized particles exiting the plasma, the higher the quenching rate-thereby allowing certain desired microstructures to be locked-in.
• Residence time of the particles within the hot zone of the plasma can also be adjusted to provide control over the resulting microstructure. That is, the length of time the particles are exposed to the plasma determines the extent of melting of the particle (i.e., surface of the particle melted as compared to the inner most portion or core of the particle). Consequently, the extent of melting effects the extent of cooling needed for solidification and thus it is a cooling process parameter. Microstructural changes can be incorporated throughout the entire particle or just a portion thereof depending upon the extent of particle melting. Residence time can be adjusted by adjusting such operating variables of particle injection rate and flow rate (and conditions, such as laminar flow or turbulent flow) within the hot zone. Equipment changes can also be used to adjust residence time.
• residence time can be adjusted by changing the cross-sectional area of the hot zone.
• Another cooling processing parameter that can be varied or controlled is the composition of the cooling gas. Certain cooling gases are more thermally conductive than others. For example helium is considered to be a highly thermally conductive gas. The higher the thermal conductivity of the cooling gas, the faster the spheroidized particles can be cooled/quenched. By controlling the composition of the cooling gas (e.g., controlling the quantity or ratio of high thermally conductive gasses to lesser thermally conductive gases) the cooling rate can be controlled.
• the microstructure of a metal is determined by the composition of the metal and heating and cooling/quenching of the material.
• the phase of the metallic material depends upon the compositions of the feed stock material (e.g., purity, composition of alloying elements, etc.) as well thermal processing. Titanium has two distinct phases known as the alpha phase (which has a hexagonal close packed crystal structure) and a beta phase which has a body centered cubic structure. Titanium can also have a mixed ⁇ + ⁇ phase. The different crystal structures yield different mechanical responses.
• inert gas is continually purged surrounding a powdered metal feed to remove oxygen within a powder-feed hopper.
• a continuous volume of powder feed is then entrained within an inert gas and fed into the microwave generated plasma for dehydrogenation or for composition/maintaining purity of the spheroidized particles.
• the microwave generated plasma may be generated using a microwave plasma torch, as described in U.S. Patent Publication No.
• the particles are exposed to a uniform temperature profile at between 4,000 and 8,000 K within the microwave generated plasma. In some embodiments, the particles are exposed to a uniform temperature profile at between 3,000 and 8,000 K within the microwave generated plasma.
• the powder particles are rapidly heated and melted. Liquid convection accelerates H2 diffusion throughout the melted particle, continuously bringing hydrogen (H2) to the surface of the liquid metal hydride where it leaves the particle, reducing the time each particle is required to be within the process environment relative to solid-state processes.
• the particle size distribution of the feed materials is maintained in the end products.
• the melted metals are inherently spheroidized due to liquid surface tension. As the microwave generated plasma exhibits a substantially uniform temperature profile, more than 90% spheroidization of particles could be achieved (e.g., 91%, 93%, 95%, 97%, 99%, 100%).
• inert gas is continually purged surrounding a powdered metal feed to remove oxygen within a powder-feed hopper.
• a continuous volume of powder feed is then entrained within an inert gas and fed into the microwave generated plasma for composition/maintaining purity of the spheroidized particles.
• the microwave generated plasma may be generated using a microwave plasma torch, as described in U.S. Patent Publication No. US 2013/0270261, and/or U.S. Patent No. 8,748,785, each of which is hereby incorporated by reference in its entirety.
• the particles are exposed to a uniform temperature profile at between 4,000 and 8,000 K within the microwave generated plasma.
• the powder particles are rapidly heated and melted.
• an inert gas such as argon
• the particles within the process are entrained within an inert gas, such as argon, generally contact between particles is minimal, greatly reducing the occurrence of particle agglomeration.
• the need for post-process sifting is thus greatly reduced or eliminated, and the resulting particle size distribution could be practically the same as the particle size distribution of the input feed materials.
• the particle size distribution of the feed materials is maintained in the end products. [0135]
• the melted metals are inherently spheroidized due to liquid surface tension.
• FIG.10 is a flow chart illustrating an exemplary method (250) for producing spherical powders, according to an embodiment of the present disclosure.
• the process (250) begins by introducing a feed material into a plasma torch (255).
• the plasma torch is a microwave generated plasma torch or an RF plasma torch.
• the feed materials are exposed to a plasma causing the materials to melt, as described above (260).
• the melted materials are spheroidized by surface tension, as discussed above (260b).
• the products cool and solidify, locking in the spherical shape and are then collected (265).
• the plasma torch can be a microwave generated plasma or an RF plasma torch.
• an AT-1200 rotating powder feeder available from Thermach Inc.
• the powder can be fed into the plasma using other suitable means, such as a fluidized bed feeder.
• the feed materials may be introduced at a constant rate, and the rate may be adjusted such that particles do not agglomerate during subsequent processing steps.
• the feed materials to be processed are first sifted and classified according to their diameters, with a minimum diameter of 1 micrometers ( ⁇ m) and a maximum diameter of 22 ⁇ m, or a minimum of 5 ⁇ m and a maximum of 15 ⁇ m, or a minimum of 15 ⁇ m and a maximum of 45 ⁇ m or a minimum of 22 ⁇ m and a maximum of 44 ⁇ m, or a minimum of 20 ⁇ m to a maximum of 63 ⁇ m, or a minimum of 44 ⁇ m and a maximum of 70 ⁇ m, or a minimum of 70 ⁇ m and a maximum of 106 ⁇ m, or a minimum of 105 ⁇ m to a maximum of 150 ⁇ m, or a minimum of 106 ⁇
• these upper and lower values are provided for illustrative purposes only, and alternative size distribution values may be used in other embodiments.
• This eliminates recirculation of light particles above the hot zone of the plasma and also ensures that the process energy present in the plasma is sufficient to melt the particles without vaporization. Pre-screening allows efficient allocation of microwave power necessary to melt the particles without vaporizing material.
• the environment and/or sealing requirements of the bins are carefully controlled. That is, to prevent contamination or potential oxidation of the powders, the environment and or seals of the bins are tailored to the application.
• the bins are under a vacuum.
• the bins are hermetically sealed after being filled with powder generated in accordance with the present technology.
• the bins are back filled with an inert gas, such as, for example argon. Because of the continuous nature of the process, once a bin is filled, it can be removed and replaced with an empty bin as needed without stopping the plasma process. [0139]
• the methods and processes in accordance with the disclosure can be used to make spherical metal powders or spherical metal alloy powders. For example, if the starting feed material is a titanium material, the resulting powder will be a spherical titanium powder. If the starting feed material is a titanium alloy material, the resulting powder will be a spherical titanium alloy powder.
• the resulting spherical titanium alloy powder comprises spherioidized particles of Ti Al6-V4, with between 4% to 7% weight aluminum (e.g., 5.5 to 6.5% Al) (or about 4% to about 7%, or about 5.5% to about 6.5%) and 3% to 5% weight vanadium (e.g., 3.5 to 4.5% vanadium) (or about 3% to about 5%, or about 3.5 to about 4.5%).
• the material may have a composition that is within 10% (+/- 10%) of the wt. % listed in this paragraph.
• the feed material may be Ti Al6-V4 (or Ti-6-4) and wherein the melting and spheroidizing is controlled such that the spheroidized powder comprises Ti Al6-V4 as discussed herein.
• both the initial feedstock and the final powder is Ti Al6-V4.
• the starting feedstock and final powder can have a different composition, but still be within the Ti Al6-V4 discussed herein.
• the starting feedstock and final powder can have a different composition.
• the processing discussed herein such as the microwave plasma processing, can be controlled to prevent and/or minimize aluminum for escaping the feedstock during the melt, which can maintain the desired composition/microstructure.
• FIG.11 illustrates an exemplary microwave plasma torch 2 that can be used in the production of spheroidal metal or metal alloy powders, according to embodiments of the present disclosure.
• metal feed materials 9, 10 can be introduced into a microwave plasma torch 3, which sustains a microwave generated plasma 11.
• an entrainment gas flow and a sheath flow may be injected through inlets 5 to create flow conditions within the plasma torch prior to ignition of the plasma 11 via microwave radiation source 1.
• the entrainment flow and sheath flow are both axis-symmetric and laminar, while in other embodiments the gas flows are swirling.
• the feed materials 9 are introduced axially into the microwave plasma torch, where they are entrained by a gas flow that directs the materials toward the plasma.
• the gas flows can consist of a noble gas column of the periodic table, such as helium, neon, argon, etc.
• the feed materials are melted in order to spheroidize the materials.
• Inlets 5 can be used to introduce process gases to entrain and accelerate particles 9, 10 along axis 12 towards plasma 11. First, particles 9 are accelerated by entrainment using a core laminar gas flow (upper set of arrows) created through an annular gap within the plasma torch.
• a second laminar flow (lower set of arrows) can be created through a second annular gap to provide laminar sheathing for the inside wall of dielectric torch 3 to protect it from melting due to heat radiation from the hot zone 6 and plasma 11.
• the laminar flows direct particles 9, 10 toward the plasma 11 along a path as close as possible to axis 12, exposing them to a substantially uniform temperature within the plasma.
• suitable flow conditions are present to keep particles 10 from reaching the inner wall of the plasma torch 3 where plasma attachment could take place.
• Particles 9, 10 are guided by the gas flows towards microwave plasma 11 were each undergoes homogeneous thermal treatment.
• Various parameters of the microwave generated plasma, as well as particle parameters, may be adjusted in order to achieve desired results.
• FIGS. 12A-B illustrates an exemplary microwave plasma torch that includes a side feeding hopper rather than the top feeding hopper shown in the embodiment of FIG. 11, thus allowing for downstream feeding.
• the feedstock is injected after the microwave plasma torch applicator for processing in the “plume” or “exhaust” of the microwave plasma torch.
• the plasma of the microwave plasma torch is engaged at the exit end of the plasma torch to allow downstream feeding of the feedstock, as opposed to the top-feeding (or upstream feeding) discussed with respect to FIG. 11.
• This downstream feeding can advantageously extend the lifetime of the torch as the hot zone 6 is preserved indefinitely from any material deposits on the walls of the hot zone liner.
• it allows engaging the plasma plume downstream at temperature suitable for optimal melting of powders through precise targeting of temperature level and residence time. For example, there is the ability to dial the length of the plume using microwave powder, gas flows, and pressure in the quenching vessel that contains the plasma plume.
• the downstream approach may allow for the use of wire feedstocks instead to produce spheroidized materials such as metals which may include aluminum, Iconel, titanium, molybdenum, tungsten, and rhenium.
• This spheroidization method can be applied to both ceramics and metals.
• the downstream spheroidization method can utilize two main hardware configurations to establish a stable plasma plume which are: annular torch, such as described in U.S. Pat. Pub. No. 2018/0297122, or swirl torchas described in US 8748785 B2 and US 9932673 B2 .
• FIG. 12A and FIG. 12B show embodiments of a method that can be implemented with either an annular torch or a swirl torch.
• a feed system close-coupled with the plasma plume at the exit of the plasma torch is used to feed powder axisymmetrically to preserve process homogeneity.
• Other feeding configurations may include one or several individual feeding nozzles surrounding the plasma plume.
• the feedstock powder can enter the plasma from any direction and can be fed in 360° around the plasma.
• the feedstock powder can enter the plasma at a specific position along the length of the plasma plume where a specific temperature has been measured and a residence time estimated for sufficient melting of the particles.
• the melted particles exit the plasma into a sealed chamber where they are quenched then collected.
• the metal feed materials 314 can be introduced into a microwave plasma torch 302.
• a hopper 306 can be used to store the metal feed material 314 before feeding the metal feed material 314 into the microwave plasma torch 302, plume, or exhaust.
• the feed material 314 can be injected at any angle to the longitudinal direction of the plasma torch 302. 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or 55 degrees.
• the feedstock can be injected an angle of greater than 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or 55 degrees.
• the feedstock can be injected an angle of less than 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, or 55 degrees.
• the feedstock can be injected along the longitudinal axis of the plasma torch.
• the microwave radiation can be brought into the plasma torch through a waveguide 304.
• the feed material 314 is fed into a plasma chamber 310 and is placed into contact with the plasma generated by the plasma torch 302. When in contact with the plasma, plasma plume, or plasma exhaust, the feed material melts. While still in the plasma chamber 310, the feed material 314 cools and solidifies before being collected into a container 312. Alternatively, the feed material 314 can exit the plasma chamber 310 while still in a melted phase and cool and solidify outside the plasma chamber. In some embodiments, a quenching chamber may be used, which may or may not use positive pressure. While described separately from FIG. 11, the embodiments of FIGS. 12A-B are understood to use similar features and conditions to the embodiment of FIG. 11.
• implementation of the downstream injection method may use a downstream swirl, extended spheroidization, or quenching.
• a downstream swirl refers to an additional swirl component that can be introduced downstream from the plasma torch to keep the powder from the walls of the tube.
• An extended spheroidization refers to an extended plasma chamber to give the powder longer residence time.
• it may not use a downstream swirl, extended spheroidization, or quenching.
• it may use one of a downstream swirl, extended spheroidization, or quenching.
• it may use two of a downstream swirl, extended spheroidization, or quenching.
• Injection of powder from below may results in the reduction or elimination of plasma-tube coating in the microwave region.
• the coating becomes too substantial, the microwave energy is shielded from entering the plasma hot zone and the plasma coupling is reduced. At times, the plasma may even extinguish and become unstable. Decrease of plasma intensity means decreases in spheroidization level of the powder.
• coating in this region is eliminated and the microwave powder to plasma coupling remains constant through the process allowing adequate spheroidization.
• the downstream approach may allow for the method to run for long durations as the coating issue is reduced.
• FIG. 13 illustrates an exemplary method (500) of producing spheroidized titanium particles with a tailored or desired microstructure.
• Method 500 includes several processing steps to treat metallic feed materials such as, for example, titanium feed materials (e.g., titanium or titanium alloys) to create spheroidized metallic particles with a desired microstructure.
• metallic feed materials e.g., titanium based
• metallic feed materials comprising particles are feed into a plasma torch.
• the particles can be produced from crushing, pulverizing, or milling feed stock materials.
• the feed stock particles have an average particle size of between 1 micron and 300 microns.
• step 515 the feed stock particles are exposed to a microwave generated plasma to melt at least the surface portion of the particles. The melted portions of the particles allow for spheriodization of the particles.
• step 520 the spheroidized particles are exposed to an inert gas such helium, nitrogen, argon or combinations/mixtures thereof.
• step 525 the cooling processing variables/conditions are set and maintained to achieve a desired microstructure. For example, in embodiments in which a martensitic microstructure is desired throughout the entire particle, the cooling processing conditions are set for rapid cooling.
• FIG. 14 illustrates an exemplary method (600) of modifying metallic feed stock material to have a spheroidized shape and a desired microstructure.
• the method of 600 includes several processing steps to treat metallic feed materials such as, for example, titanium feed materials (e.g., titanium or titanium alloys) to create spheroidized metallic particles with a desired microstructure.
• step 610 the composition of the Ti-based feed stock material is selected or analyzed to determine its composition.
• step 615 a desired microstructure of a final product is determined. For example, it may be determined that an ⁇ - phase 99% pure Ti equiaxed microstructure throughout the spheroidized particle is desired. As a result, a slower rate of cooling will be required than that used to produce a martensitic microstructure.
• Cooling processing parameters will be selected (step 620), such as cooling gas flow rate, residence time, and/or composition of cooling gas to achieve such a microstructure based upon the composition of the feed stock materials.
• the microstructure of the final product will differ from the original feed stock material. That is an advantage of the present method is to be able to efficiently process feed materials to create spheroidized particles with a desired microstructure.
• the feed stock particles are melted in the microwave generated plasma to spheriodize the particles in step 625.
• the spheroidized particles are exposed to an inert gas (step 630) and the determined or selected cooling parameters are applied to form the desired microstructure.
• the desired microstructure of the spheroidized particle (end product) can be tailored to meet the demands and material characteristics of its use.
• the desired microstructure may be one that provides improved ductility (generally associated with the ⁇ - phase).
• the desired microstructure may be associated with the inclusion of ⁇ + ⁇ phase or regions of ⁇ with islands of ⁇ phase or vice-versa.
• FIG.15 shows such an embodiment. This figure illustrates a spheroidal particle which has two distinct regions. The outer or shell region 715 and an inner core 710.
• the original titanium feed material for this particle was a pure titanium ⁇ - phase powder. The feed material was exposed to the plasma under conditions (temperature, residence time, etc.) such that only a surface portion of the particle melted, so that spheriodization could occur.
• both the shell and the inner core are Ti- 6-4.
• the core composition/microstructure is retained, such as keeping Ti-6-4, and the shell composition/microstructure can be changed.
• the entire feed stock particle can be melted and cooling parameters can be selected and applied to create a crystal structure that has the same phase as the feed stock material (e.g., retains ⁇ -phase) or is transformed to a new phase or mixture of phases.
• Embodiment 1 A method for manufacturing a spheroidized powder from scrap metal or used metal parts, the method comprising: introducing metallic particles obtained by milling or crushing scrap metal or used metal parts into a microwave plasma torch; and melting and spheroidizing the metallic particles within the microwave plasma torch to form spheroidized powder.
• Embodiment 2 The method of Embodiment 1, wherein the milled or crushed particles have a desired particle size distribution.
• Embodiment 3. The method of Embodiment 2, wherein the desired particle size distribution is 15 to 63 microns.
• Embodiment 4. The method of Embodiment 1, wherein the milled or crushed particles have a desired range of particle volumes.
• Embodiment 5. The method of any of the preceding embodiments, wherein the particles are milled or crushed without embrittling the scrap metal or used metal parts.
• Embodiment 6. The method of any of the preceding embodiments, further comprising milling or crushing the scrap metal or used metal parts to produce the metallic particles.
• the metallic particles comprise milled turnings resulting from subtractive manufacturing.
• Embodiment 13 The method of any one of Embodiments 1-11, wherein the scrap metal or used metal parts comprise sharp turnings, saw swarfs, grinding swarfs, grinding fines, and/or wash line fines.
• Embodiment 14 The method of any of the preceding embodiments, wherein the metallic particles comprise a work hardened microstructure that is at least partially retained after the melting and spheroidizing.
• Embodiment 15 The method of any of the preceding embodiments, wherein the metallic particles are only partially surface melted.
• a method for manufacturing a spheroidized powder from scrap metal or used metal parts comprising: providing scrap metal or used metal parts comprising titanium, titanium alloy or other ductile metal or ductile metal alloy; milling the scrap metal or used metal parts to produce metallic particles within a range of particle volumes pre-determined to be suitable for use as feedstock in a microwave plasma process, wherein the scrap metal or used metal parts are selected for the milling to have a size and/or aspect ratio that will result post-milling in metallic particles within the pre-determined range of particle volumes, wherein the milling occurs without embrittling the scrap metal or used metal parts; and applying the microwave plasma process to the metallic particles within the determined range of particle volumes to form spheroidized powder.
• scrap metal or used metal parts comprising titanium, titanium alloy or other ductile metal or ductile metal alloy
• milling the scrap metal or used metal parts to produce metallic particles within a range of particle volumes pre-determined to be suitable for use as feedstock in a microwave plasma process, wherein the scrap metal or used metal parts are selected
• Embodiment 16 further comprising selecting portions of the scrap metal or used metal parts having a size and/or aspect ratio suitable for milling to the determined range of particle volumes.
• Embodiment 18 The method of Embodiment 16 or 17, wherein the determined range of particle volumes is between 15 and 63 microns.
• Embodiment 19 The method of any one of Embodiments 16-18, wherein the scrap metal or used metal parts comprise a work hardened microstructure that is retained in the spheroidized powder after applying the microwave plasma process.
• Embodiment 20 The method of any one of Embodiments 16-19, wherein the milling is performed in water.
• Embodiment 21 The method of any one of Embodiments 16-19, wherein the milling is performed in water.
• Embodiment 22 The method of any one of Embodiments 16-21, comprising milling the scrap metal or used metal parts without embrittling the scrap metal or used metal parts by hydrogenation or applying cryogenics.
• Embodiment 23 The method of any one of Embodiments 16-22, wherein the scrap metal or used metal parts comprise turnings resulting from subtractive manufacturing.
• Embodiment 24 The method of any one of Embodiments 16-23, wherein the scrap metal or used metal parts comprises Ti-6-4.
• Embodiment 25 A method of additive manufacturing, comprising using the spheroidized powder resulting from any one of Embodiments 16-24.
• Embodiment 26 A method of laser bed fusion, comprising using the spheroidized powder resulting from any one of Embodiments 16-24.
• Embodiment 27 A method of electron beam manufacturing, comprising using the spheroidized powder resulting from any one of Embodiments 16-24.
• Embodiment 28 A method of metal injection molding, comprising using the spheroidized powder resulting from any one of Embodiments 15-23.
• Embodiment 29 A method of laser bed fusion, comprising using the spheroidized powder resulting from any one of Embodiments 16-24.
• a method for manufacturing a spheroidized powder from scrap metal or used metal parts comprising: providing scrap metal or used metal parts; milling the scrap metal or used metal parts to produce metallic particles within a range of particle volumes pre-determined to be suitable for use as feedstock in a microwave plasma process, wherein the scrap metal or used metal parts are selected for the milling to have a size and/or aspect ratio that will result post-milling in metallic particles within the pre-determined range of particle volumes, wherein the milling occurs without embrittling the scrap metal or used metal parts; and applying the microwave plasma process to the metallic particles within the determined range of particle volumes to form spheroidized powder.
• Embodiment 30 Embodiment 30.
• Embodiment 31 A method for manufacturing a spheroidized powder from used powder, the method comprising: introducing previously used powder particles into a microwave plasma torch; and melting and spheroidizing the previously used powder particles within the microwave plasma torch to form spheroidized powder particles.
• Embodiment 32 The method of Embodiment 31, wherein the previously used powder particles have a desired particle size distribution.
• Embodiment 33 The method of any one of Embodiments 31-32, wherein the previously used powder particles comprise satellites, wherein the satellites are removed during the melting and spheroidizing.
• Embodiment 34 A method for manufacturing a spheroidized powder from used powder, the method comprising: introducing previously used powder particles into a microwave plasma torch; and melting and spheroidizing the previously used powder particles within the microwave plasma torch to form spheroidized powder particles.
• Embodiment 31-33 wherein the previously used powder particles comprise agglomerations, wherein the agglomerations are removed during the melting and spheroidizing.
• Embodiment 35 The method of any one of Embodiments 31-34, wherein the previously used powder particles comprise contaminants, wherein the contaminants are removed during the melting and spheroidizing.
• Embodiment 36 The method of any one of Embodiments 31-35, wherein the previously used powder particles comprise metal or metal alloys.
• Embodiment 37 The method of any one of Embodiments 31-36, wherein the previously used powder particles comprise titanium or titanium alloy.
• Embodiment 38 The method of any one of Embodiments 31-33, wherein the previously used powder particles comprise agglomerations, wherein the agglomerations are removed during the melting and spheroidizing.
• Embodiment 39 The method of any one of Embodiments 31-36, wherein the previously used powder particles comprise a ductile metal or metal alloy.
• Embodiment 40 The method of any one of Embodiments 31-36, wherein the previously used powder particles comprise cobalt or cobalt alloy.
• Embodiment 41 The method of any one of Embodiments 31-36, wherein the previously used powder particles comprise steel and steel alloy.
• Embodiment 42. The method of any one of Embodiments 31-36, wherein the previously used powder particles comprise a ceramic.
• Embodiment 43 The method of any one of Embodiments 31-36, wherein the previously used powder particles comprise a ceramic.
• Embodiment 44 The method of any one of Embodiments 31-42, wherein the melting and spheroidizing improves flowability of the previously used powder particles.
• Embodiment 44 The method of any one of Embodiments 31-43, wherein the melting and spheroidizing increases density of the previously used powder particles.
• Embodiment 45 The method of any one of Embodiments 31-44, wherein carbon, nitrogen and/or other contaminants are removed from the previously used powder particles during the melting and spheroidizing.
• Embodiment 46 The method of any one of Embodiments 31-45, wherein a noble gas, argon gas, a mixture of argon gas and hydrogen gas, or nitrogen gas is used during the melting and spheroidizing.
• Embodiment 47 The method of any one of Embodiments 31-42, wherein the melting and spheroidizing improves flowability of the previously used powder particles.
• Embodiment 44 The method of any one of Embodiments 31
• Embodiment 48 The method of any one of Embodiments 31-46, wherein the previously used powder particles were formed from an additive manufacturing process.
• Embodiment 48 The method of Embodiment 47, wherein the additive manufacturing process comprises laser sintering, electron-beam melting, filament fused deposition, directed energy deposition, powder bed fusion, or binder jetting.
• Embodiment 49 The method of any one of Embodiments 31-48, wherein the spheroidized powder particles retain the same rheological properties as the previously used powder particles after the melting and spheroidizing.
• Embodiment 50 The method of any one of Embodiments 31-46, wherein the previously used powder particles were formed from an additive manufacturing process.
• Embodiment 48 The method of Embodiment 47, wherein the additive manufacturing process comprises laser sintering, electron-beam melting, filament fused deposition, directed energy deposition, powder bed fusion, or binder jetting.
• Embodiment 49 The method of any one of
• Embodiment 51 The method of any one of Embodiments 31-50, wherein the previously used powder particles substantially only comprise particles that are not spheroidal.
• Embodiment 52 The method of any one of Embodiments 31-50, wherein the previously used powder particles substantially only comprise particles that have satellites, contaminants, and/or agglomerations.
• Embodiment 53 The method of any one of Embodiments 31-49, wherein alloy component chemistry and/or minor component chemistry being less than 10 wt% are the same in the spheroidized powder particles as the previously used powder particles.
• Embodiment 54 A method for producing a spheroidized powder from a feed material comprising dehydrogenated or non-hydrogenated titanium or titanium alloy, the method comprising: introducing a feed material comprising dehydrogenated or non-hydrogenated titanium or titanium alloy particles into a microwave plasma torch; and melting and spheroidizing the particles within a plasma generated by the microwave plasma torch to form spheroidized powder.
• Embodiment 55 A method for producing a spheroidized powder from a feed material comprising dehydrogenated or non-hydrogenated titanium or titanium alloy, the method comprising: introducing a feed material comprising dehydrogenated or non-hydrogenated titanium or titanium alloy particles into a microwave plasma torch; and melting and spheroidizing the particles within a plasma generated by the microwave plasma torch to form spheroidized powder.
• Embodiment 54 wherein the feed material comprises titanium or titanium alloy particles processed by the hydrogenation-dehydrogenation (HDH) process.
• Embodiment 56 The method of any one of Embodiments 54-55, wherein the spheroidized powder comprises particles with a median sphericity of at least 0.75.
• Embodiment 57 The method of any one of Embodiments 54-56, wherein the spheroidized powder comprises particles with a median sphericity of at least 0.91.
• Embodiment 58 The method of any one of Embodiments 54-57, wherein the spheroidized powder has a particle size distribution of 15 to 45 microns.
• Embodiment 59 The method of any one of Embodiments 54-57, wherein the spheroidized powder has a particle size distribution of 15 to 45 microns.
• Embodiment 60 The method of any one of Embodiments 54-58, wherein the spheroidized powder has a particle size distribution of 45 to 105 microns.
• Embodiment 60 The method of any one of Embodiments 54-59, further comprising exposing the spheroidized particles to an inert gas.
• Embodiment 61 The method of any one of Embodiments 54-60, further comprising setting one or more cooling processing variables to tailor the microstructure of the spheroidized particles.
• Embodiment 62 The method of Embodiment 61, wherein setting one or more cooling processing variables comprises selecting and controlling a cooling gas flow rate.
• Embodiment 63 The method of any one of Embodiments 54-58, wherein the spheroidized powder has a particle size distribution of 45 to 105 microns.
• Embodiment 60 The method of any one of Embodiments 54-59, further comprising exposing the spheroidized particles to an iner
• Embodiment 61 wherein setting one or more cooling processing variables comprises selecting and controlling a residence time of the particles of feed materials within the plasma.
• Embodiment 64 The method of Embodiment 61, wherein setting one or more cooling processing variables comprises selecting and controlling a cooling gas composition.
• Embodiment 65 The method of Embodiment 64, wherein the cooling gas composition is selected to provide high thermal conductivity.
• Embodiment 66 The method of Embodiment 61, wherein one or more cooling processing variables are set to create a martensitic microstructure in the spheroidized particles.
• Embodiment 67 The method of Embodiment 61, wherein setting one or more cooling processing variables comprises selecting and controlling a residence time of the particles of feed materials within the plasma.
• Embodiment 64 The method of Embodiment 61, wherein setting one or more cooling processing variables comprises selecting and controlling a cooling gas composition.
• Embodiment 65 The method of Embodiment 64, wherein the cooling gas composition is selected
• Embodiment 61 wherein one or more cooling processing variables are set to create a Widman Toon microstructure in the spheroidized particles.
• Embodiment 68 The method of Embodiment 61, wherein one or more cooling processing variables are set to create an equiaxed microstructure in the spheroidized particles.
• Embodiment 69 The method of Embodiment 61, wherein one or more cooling processing variables are set to create at least two regions, each region having a different microstructure.
• Embodiment 70 The method of Embodiment 69, wherein the at least two regions include a core portion and a skin portion.
• Embodiment 71 Embodiment 71.
• Embodiment 70 wherein the skin portion has a microstructure that is different from the feed material’s microstructure.
• Embodiment 72 The method of any one of Embodiments 54-71, wherein melting and spheroidizing of the particles occurs within a substantially uniform temperature profile between about 4,000K and 8,000K.
• Embodiment 73 The method of any one of Embodiments 54-71, wherein the feed material has a particle size of no less than 1.0 microns and no more than 300 microns.
• Embodiment 74 The method of any one of Embodiments 54-71, wherein the feed material comprises Ti-6-4, and wherein the melting and spheroidizing is controlled such that the spheroidized powder comprises Ti-6-4.
• Embodiment 75 A spheroidized powder manufactured according to the method of any of Embodiments 31-74.
• the terms “approximately”, “about”, “generally,” and “substantially” may refer to an amount that is within less than or equal to 10% of, within less than or equal to 5% of, within less than or equal to 1% of, within less than or equal to 0.1% of, and within less than or equal to 0.01% of the stated amount. If the stated amount is 0 (e.g., none, having no), the above recited ranges can be specific ranges, and not within a particular % of the value. For example, within less than or equal to 10 wt./vol. % of, within less than or equal to 5 wt./vol. % of, within less than or equal to 1 wt./vol.

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