Atomization assembly

Abstract

The atomization assembly comprises a crucible, a copper nozzle extending below the copper crucible and configured to receive metal from the copper crucible, and a cooling system in fluid communication with one or more cooling passages of the copper nozzle during operation of the atomization assembly in its manufacturing mode, wherein during operation of the atomization assembly in its manufacturing mode, the atomization assembly determines an energy conversion factor (ECF) of 1% (0.01) to 30% (0.30).

Description

Technical Field

[0001] The present disclosure relates to an atomization assembly and a method of forming metal powder.

Background Art

[0002] Additive manufacturing processes generally involve the buildup of one or more materials to create net shape or near-net shape (NNS) objects, in contrast to subtractive manufacturing methods. "Additive manufacturing" is an industry standard term, but additive manufacturing encompasses various manufacturing and prototyping techniques known by various additive manufacturing terms such as freeform manufacturing, 3D printing, rapid prototyping / tooling, etc. Additive manufacturing techniques can produce complex parts from a variety of materials. In general, self-standing objects can be manufactured from a computer-aided design (CAD) model.

[0003] A common type of powder bed additive manufacturing process called electron beam melting (EBM) produces three-dimensional (3D) objects by sintering, melting, or otherwise fusing fine powder using an electron beam. Laser sintering or melting is also a notable additive manufacturing process that selectively fuses various material systems such as engineering plastics, thermoplastic elastomers, metals, and ceramics using a laser beam. In both the EBM and laser sintering / melting processes, the powder to be melted is evenly spread over a powder bed on a build platform, and the energy beam sinters or melts a cross-sectional layer of the object being built under the control of an electronic control unit or a radiation guiding device. The build platform is lowered, another powder layer is spread over the powder bed and the object being built, and subsequent continuous melting / sintering of the powder is performed. This process is repeated until the part is completely built from the melted / sintered powder material.

[0004] Regardless of the type of powder bed additive manufacturing process, the physical and chemical properties of the added powder can affect the quality of the resulting object. In other words, the properties of parts constructed by additive manufacturing depend on the metal powder itself; higher quality powder (e.g., denser, cleaner, and more spherical) exhibits more predictable behavior and therefore results in better parts. For this reason, high-quality powder materials are essential for parts formed using additive manufacturing technology, especially when used in the manufacture of parts for gas turbine machinery or medical implants or devices.

[0005] A complete and implementable disclosure of this disclosure, including best embodiments for those skilled in the art, is described in the specification with reference to the accompanying drawings. [Overview of the project] [Means for solving the problem]

[0006] One aspect of the present invention is an atomizing assembly comprising: a crucible configured to receive a metal which is titanium or a titanium alloy; a copper nozzle extending below the crucible and configured to receive the metal from the crucible, defining one or more cooling passages, an inner surface and a metal outlet; and a cooling system that is in fluid communication with the one or more cooling passages of the copper nozzle to supply a flow of cooling fluid to the one or more cooling passages at a mass flow rate ●coolant (hereinafter, "●" is "m" with a "·") during operation of the atomizing assembly in a manufacturing mode, wherein during operation of the atomizing assembly in a manufacturing mode, the copper nozzle determines the maximum temperature Tsurface of the inner surface in direct contact with the metal and the mass flow rate ●metal of the metal passing through the metal outlet, the metal passing through the metal outlet determines the maximum temperature Tmetal, and determines an energy conversion coefficient (ECF) of 1% (0.01) to 30% (0.30), wherein the ECF is equal to the following formula.

number

[0007] [Figure 1] This is a schematic diagram of an exemplary system for forming metal powder through atomization. [Figure 2] This is a schematic diagram of an assembly for melting metal raw materials. [Figure 3A] Figure 2 is a cross-sectional view of the assembly. [Figure 3B] Figure 2 is a cross-sectional view of the assembly. [Figure 4] This is a cross-sectional view of another assembly for melting metal raw materials. [Figure 5] This is a diagram of the assembly in Figure 4, viewed from the direction indicated by arrow 5. [Figure 6] This is a cross-sectional view of another assembly for melting metal raw materials. [Figure 7] This is a block diagram of an exemplary method for forming metal powder. [Figure 8] This is a block diagram of another exemplary method for forming metal powder. [Figure 9] Figure 10 shows a table containing numerical values ​​corresponding to some of the atomized assemblies plotted. [Figure 10] This is a plot of a micronization assembly according to one or more exemplary embodiments of the present disclosure. [Modes for carrying out the invention]

[0008] Embodiments of the present disclosure are described in detail hereby referenced, with one or more examples shown in the accompanying drawings. In the detailed description, numbers and letters are used to refer to features in the drawings. Identical or similar notations in the drawings and description are used to refer to identical or similar parts of the present disclosure.

[0009] In this specification, the term “exemplary” is used to mean “serving as an example, case, or illustration.” Any embodiment described as “exemplary” in this specification should not necessarily be construed as being preferable or advantageous to other embodiments. Furthermore, unless otherwise specified, all embodiments described herein should be considered exemplary.

[0010] The terms "first," "second," "third," and other ordinal numbers used herein are used to distinguish one component from another and are not intended to indicate the position or importance of any individual component.

[0011] In this specification, two components are "adjacent" to each other if they are in close proximity with no other structures, components, or layers in between.

[0012] Singular forms such as "a," "an," and "the" can also refer to multiple things unless the context clearly indicates otherwise.

[0013] For example, in the context of "at least one of A, B, and C," the phrase "at least one" refers to A only, B only, C only, or any combination of A, B, and C.

[0014] The phrases "X~Y" and "between X and Y" refer to a range of values ​​that includes the endpoints (i.e., a range of values ​​that includes both X and Y).

[0015] In this context, "atomizing" a metal means forming a powder of metal particles from molten metal. That is, atomized metal particles are not individual atoms of pure metal or metal alloy, but particles of a size suitable for additive manufacturing. In gas atomization processes, a flow of gas (such as argon) is directed towards a flow of molten metal, causing the molten metal to split into droplets, which then solidify into a powder of metal particles. Atomization of reactive powders is typically performed using a gas flow. This gas flow can be delivered at different pressures and temperatures, such as high-pressure low-temperature gas, or high-temperature gas supplied by a gas heater or plasma torch. In plasma atomization processes, a plasma flow splits the flow of molten metal into droplets. The particles can have diameters ranging from 0.001 μm to 150 μm.

[0016] In this context, "metal" refers to pure metals or metal alloys (i.e., compounds of pure metals that may or may not contain other non-oxygen elements) and not to metal oxides such as ceramics (especially aluminum oxide (alumina), silicon oxide, rust, salts, etc.) or metal salts such as sodium chloride. Examples of metals include aluminum, titanium, copper, and their alloys. "Metal powder" refers to powders containing multiple metal particles, mainly composed of pure metals or metal alloys, such as titanium powder consisting of pure titanium particles. Metal powders may contain trace amounts of interstitial elements (C, O, H, N) and other impurities or passivation layers.

[0017] The present disclosure generally relates to atomizing metals, particularly titanium and titanium alloys, into metal powders. Titanium can be recycled and titanium powder can be formed using a gas atomization process. Gas atomization uses a consumable pouring nozzle and a relatively low-temperature gas stream that interacts with the molten metal stream to atomize the molten metal stream. Such consumable nozzles formed of ceramic or refractory materials that react with titanium rapidly deteriorate, limiting the batch size and quality of titanium powder production. Further, the pouring nozzle needs to have a sufficiently large outlet to prevent clogging, reduce contamination of the molten metal (due to reaction with the molten metal), limit unduly rapid deterioration of the pouring nozzle, or for combinations thereof. Thus, it can be difficult to obtain desirable fine powders using a gas atomization process, particularly when atomizing metals having a relatively high melting point such as titanium or titanium alloys. Multiple attempts have been made to implement cooled copper pouring nozzles, but none were able to miniaturize the nozzle to supply a small metal flow rate for powder atomization.

[0018] In addition to or instead of this, a plasma atomization process can be used to atomize metals and form metal powders. Plasma atomization uses titanium wire instead of recycled powder, and the titanium wire is atomized with hot gas from one or more plasma torches. The hot plasma can melt and atomize the metal simultaneously to form the desired powder. However, it can be difficult to supply sufficient energy through the hot plasma to produce the desired fine powder, particularly when atomizing metals having a relatively high melting point such as titanium.

[0019] The inventors of the present disclosure have sought means to facilitate the production of metal powders (e.g., titanium or titanium alloy powders) that enable the production of a desired fine powder size and, if desired, the use of recycled raw materials without unduly contaminating the atomized metal and consuming the main components of the atomization system. In particular, the inventors have recognized that an atomization assembly equipped with a copper crucible and a copper nozzle can be combined with an induction heater and a cooling system (operable with both the copper crucible and the copper nozzle) and used in both a gas atomization process and a plasma atomization process to achieve these goals.

[0020] For example, the induction heater can heat the titanium raw material within the copper crucible, enabling the use of recycled powder for atomization and melting it into a molten metal stream. Copper does not react significantly with titanium, reducing or suppressing the contamination of the molten titanium. To keep the molten titanium in a liquid state while suppressing the melting of the copper crucible and the copper nozzle, a cooling system (such as a water-based cooling system) actively cools the copper crucible and the copper nozzle. The cooling system further enables the copper pouring nozzle to define a sufficiently small outlet, whereby the molten titanium is supplied to the outlet at a sufficiently low mass flow rate, enabling the production of relatively fine metal powder. In particular, even when the induction heater heats the molten titanium to a temperature far exceeding the melting point of copper, the high thermal conductivity of copper enables rapid cooling to maintain the integrity of the copper crucible and the copper nozzle. Furthermore, the induction heater extending to the copper pouring nozzle can prevent clogging of the copper pouring nozzle during and between operations, despite the relatively low mass flow rate of the molten titanium passing through the relatively small outlet of the copper pouring nozzle.

[0021] In particular, the inventors, in the process of designing atomization assemblies having the above structure, unexpectedly discovered that the costs associated with including both induction heaters and cooling systems that operate at a sufficiently high level to cool the vessel / nozzle where the metal is molten, respectively, can be overcome by the advantages associated with the atomization assemblies of this disclosure (e.g., having a non-consumable copper nozzle, obtaining a sufficiently high percentage of atomized powder at a desired fine size), contrary to conventional thinking and expectations. In particular, the inventors, in the process of designing several atomization systems having the above structure, discovered that there is a relationship between the mass flow rate of molten metal passing through the outlet of the copper nozzle, the mass flow rate of coolant passing through the copper nozzle supplied by the cooling system, the maximum surface temperature of the copper surface in direct contact with the solidified molten metal, and the maximum temperature of the molten metal passing through the outlet of the copper nozzle, and that including the above structure according to one or more exemplary embodiments described herein may bring net benefits to the atomization system design.

[0022] With the goal of achieving an improved atomization system that can produce metal powders of a desired fine powder size (e.g., titanium) without contaminating the metal being atomized or consuming the main components of the atomization system, and that allows for the use of recycled materials as needed, the inventors designed several different types of atomization systems, including the atomization system described herein, in the design process by designing an atomization system having the above structure with various metal and coolant mass flow rates, maximum metal temperature, and maximum surface temperature in the copper nozzle, verifying the operability and powder properties achieved by the designed atomization system, redesigning the atomization system by changing the above parameters based on the impact on other aspects of the atomization system, and re-verifying the operability and powder properties of the redesigned atomization system. These atomization systems will be described in more detail later.

[0023] Next, referring to drawings where the same reference number throughout indicates the same element, Figure 1 is a schematic diagram of an exemplary system 100 for forming metal powder 102 by atomization. The system 100 includes a melting chamber 104 and an atomization chamber 106. Here, a metal raw material 108, shown in the form of a rod, melts into molten metal 110, the molten metal 110 is atomized into droplets 112, and the droplets 112 solidify in the atomization chamber 106 to form metal powder 102.

[0024] The atomization chamber 106 includes a vacuum pump 114 and a powder collection container 116. The vacuum pump 114 exhausts almost all the air from inside the atomization chamber 106, reducing oxygen contamination of the metal powder 102. After exhausting the air, an inert gas (such as argon) is supplied to the atomization chamber 106 to maintain the pressure difference between the melting chamber 104 and the atomization chamber 106. In this configuration, the gas pressure inside the melting chamber 104 is higher than the gas pressure inside the atomization chamber 106. This pressure difference reduces or suppresses the return of the metal powder 102 formed inside the atomization chamber 106 to the melting chamber 104. The metal powder 102 settles into the powder collection container 116 by gravity and is stored there.

[0025] The melting chamber 104 includes an assembly 120 for melting the metal raw material 108. The assembly 120 melts the metal raw material 108 into a flow of molten metal 110, atomizes the molten metal 110 into droplets 112, and the droplets 112 solidify in the atomization chamber 106 to form metal powder 102.

[0026] Next, referring to Figures 2 to 3B, schematic diagrams of assembly 120 are shown. Figure 2 shows an enlarged view of assembly 120. Figure 3A shows a cross-sectional view of assembly 120 with a water cooling system. Figure 3B shows a cross-sectional view of assembly 120 with two water cooling systems.

[0027] Assembly 120 includes a copper crucible 122 and a copper nozzle 124. The copper crucible 122 is positioned to hold the metal raw material 108. The copper nozzle 124 is located below and adjacent to the copper crucible 122. As shown in Figure 2, the copper nozzle 124 and the copper crucible 122 can be separate parts. Alternatively, although not shown in the figure, the copper crucible 122 and the copper nozzle 124 can be part of the same part. In this configuration, the “crucible” is part of a part having a diameter greater than a specified value, such as 0.75 inches, and the “nozzle” is part of a part having a diameter smaller than a specified value.

[0028] The copper nozzle 124 is adjacent to the copper crucible 122 and directs the flow of molten metal 110 downwards. The copper crucible 122 and the copper nozzle 124 are located in the molten chamber 104 above the atomization chamber 106. The copper nozzle 124 controls the flow rate of the molten metal 110 by forming a choke point and delivers the molten metal 110 to the location of the atomization fluid supply unit, which will be described in more detail later, in order to atomize it.

[0029] The copper crucible 122 and copper nozzle 124 are formed from pure copper or a copper alloy in particular, so as to maintain the rigidity of the copper crucible 122 and copper nozzle 124 by cooling the copper while the metal raw material 108 is melted into the molten metal 110. In this context, the nozzle and crucible are made from a material with high electrical and thermal conductivity, such as high-purity copper (e.g., 99.9% copper) or a copper alloy. The copper crucible 122 and copper nozzle 124 may be formed from the same copper alloy. Alternatively, the copper crucible 122 and copper nozzle 124 may be made from different copper alloys, different copper concentrations, or combinations thereof. The copper crucible 122 and copper nozzle 124 can be manufactured by additive manufacturing to improve the shape of each of the specific features.

[0030] The copper crucible 122 has one or more insulating slots 123, and the copper nozzle 124 has one or more insulating slots 125. Electrically insulating materials such as ceramics can be attached to the insulating slots 123 and 125 defined on the outer surfaces of the copper crucible 122 and the copper nozzle 124, respectively. The insulating slots 123 and 125 reduce or suppress the flow of current that may be generated, for example, by an induction heater described later.

[0031] As shown in Figures 3A and 3B, the copper crucible 122 includes an inlet 126 and an outlet 128, with an inner surface 129 further defined, and the copper nozzle 124 includes an inlet 130 and an outlet 132, with an inner surface 133 further defined. The outlet 132 is defined at the downstream end 135 of the copper nozzle 124. Metallic raw material 108 is supplied to the inlet 126 of the copper crucible 122, and the metallic raw material 108 melts into molten metal 110. The molten metal 110 flows through the outlet 128 of the copper crucible 122 to the inlet 130 of the copper nozzle 124. Next, the molten metal 110 flows through the outlet 132 of the copper nozzle 124 into the atomization chamber 106. The inlet 126 of the copper crucible 122 is larger than the outlet 132 of the copper nozzle 124 and tapers to allow the molten metal 110 to accumulate in the copper crucible 122. A layer of solidified metal 134 is formed between the molten metal 110 and the copper crucible 122 and copper nozzle 124 (on the inner surface 133 of the copper nozzle 124). The solidified metal 134 prevents the molten metal 110 (heated to a temperature higher than the melting point of copper) from reaching (and melting) the copper crucible 122 and copper nozzle 124.

[0032] Assembly 120 includes an induction heater 136 extending around a copper crucible 122 and a copper nozzle 124. The induction heater 136 includes a heating coil 138, a power supply 140, and a controller 142 (Figure 2). The heating coil 138 of the induction heater is configured to heat the metal raw material 108 to a temperature higher than the melting point of the metal when powered by the power supply 140. The controller 142 instructs the power supply 140 to supply power to the heating coil 138. As will be described in more detail later, the induction heater 136 heats the metal raw material 108 to form molten metal 110, which flows through the copper crucible 122 and the copper nozzle 124. As shown in Figure 2, the heating coil 138 is continuous and extends spirally from the copper crucible 122 to the copper nozzle 124, providing uniform heating throughout the assembly 120.

[0033] Referring again to Figure 2, the heating coil 138 of the induction heater 136 is configured to heat the metal to a temperature higher than the melting point of the metal. Specifically, the metal raw material 108 contains titanium powder. The heating coil 138 of the induction heater 136 is operated to receive a single-frequency alternating current from the power supply 140, which generates a magnetic field. The magnetic field generates eddy currents in the molten metal 110, which generates heat and maintains a specific viscosity of the molten metal 110. Specifically, the controller 142 operates the power supply 140 and the heating coil 138 to heat the molten metal 110 so that the molten metal 110 flows through the copper nozzle 124 at a flow rate within a specified flow rate threshold. The specified flow rate is determined so that the molten metal 110 is atomized to provide metal powder particles of a specific size, and also determines the temperature at which the induction heater heats the molten metal 110 above its melting point. As an example, the specified flow rate can be 4.0 kg / min or less.

[0034] The particle size of the metal powder 102 is primarily determined by the ratio of the mass flow rate of the atomizing gas to the mass flow rate of the molten metal, i.e., the gas-to-metal ratio (GMR). The higher the mass flow rate of the gas relative to the mass flow rate of the metal, the smaller the resulting powder size. Other factors such as the heating of the metal, the viscosity of the metal, the velocity of the atomizing gas, and the nozzle shape also affect the particle size of the metal powder 102. The metal raw material 108 may be preferentially preheated in an arc melting furnace or induction heater before entering the copper crucible 122. By mixing the preheated and unpreheated raw materials, scrap, slag, and other waste metal products can be recycled. Preheating the metal raw material 108 reduces the amount of energy supplied by the induction heater 136 to the molten metal 110, improving overall energy efficiency.

[0035] As shown in Figures 3A and 3B, the assembly 120 includes a cooling system 144 that has thermal communication with the copper crucible 122 and copper nozzle 124. The cooling system 144 may be a water-cooling system configured to cool the copper crucible 122 and copper nozzle 124 while the heating coil 138 heats the molten metal 110. Alternatively, other coolants such as oil or refrigerant can be used in the cooling system 144. The cooling system 144 includes a controller 146, a pump 148, a storage tank 150, and a heat exchanger 152. The controller 146 operates the pump 148 to supply water from the storage tank 150 to the copper crucible 122 and copper nozzle 124. The heat exchanger 152 cools the heated water from the copper crucible 122 and copper nozzle 124 and supplies the cooled water to the storage tank 150. The heat from the heat exchanger 152 can be transferred to the environment or to a different separate cooling system.

[0036] The cooling system 144 cools the copper crucible 122 and the copper nozzle 124. Specifically, the cooling system 144 is configured to flow water through a first cooling channel 154 of the copper crucible 122 and a second cooling channel 156 of the copper nozzle 124. The pump 148 supplies water to the first and second cooling channels 154 and 156, which cool the copper crucible 122 and the copper nozzle 124 so that all parts of the copper crucible 122 and the copper nozzle 124 are below the melting point of copper (typically around 1100°C). In one embodiment, the average temperature of the copper crucible 122 and the copper nozzle 124 is cooled to 400°C, at which point neither the copper crucible 122 nor the copper nozzle 124 substantially exceeds the melting point of copper. The cooling system 144 keeps the copper crucible 122 and copper nozzle 124 in a solid state while the induction heater heats the metal raw material 108 to a temperature above its melting point. As shown in Figure 3B, the assembly 120 may include a second cooling system 144' comprising a second controller 146', a second pump 148', a second storage tank 150', and a second heat exchanger 152'. In such a configuration, the cooling system 144 can cool only the copper crucible 122, and the second cooling system 144' can cool only the copper nozzle 124. That is, the cooling systems 144 and 144' can cool the copper crucible 122 and copper nozzle 124 independently, enabling specific temperature control of the assembly 120.

[0037] Assembly 120 includes an atomizing fluid supply unit 158 ​​located below the copper nozzle 124. The atomizing fluid supply unit 158 ​​can supply cold gas from a gas pipe, hot gas from a gas heater, or plasma from a plasma torch. The atomizing fluid supply unit 158 ​​provides a fluid flow through an outlet 160, which feeds the molten metal 110 into the atomizing chamber, splitting the flow of molten metal 110 into droplets 112 (Figure 1). The droplets 112 then solidify into metal powder 102 (Figure 1). The atomizing fluid supply unit 158 ​​may be a plasma torch or a gas torch, and the fluid flow may be a plasma flow (i.e., a fluid heated to the plasma state of matter) or a heated gas flow. The fluid may be a mixture of inert gases, including an inert gas such as argon or helium, or other gases at low concentrations, which suppress the reactivity of the molten metal 110.

[0038] Referring to Figures 4 and 5, schematic diagrams of another assembly 200 for melting the metal raw material 108 are shown. Figure 4 shows a side cross-sectional view of assembly 200. Figure 5 shows a bottom view of assembly 200. Common components between assembly 120 and assembly 200 are indicated by common numbers.

[0039] The assembly 200 includes a copper crucible 202 that holds the metal raw material 108 while it melts into molten metal 110, and a copper nozzle 204 extending downward from the copper crucible 202. The copper nozzle 204 defines a thickness T, i.e., the diameter of the copper nozzle 204. The copper nozzle 204 guides the molten metal 110 into the atomization chamber 106. The copper nozzle 204 includes an inlet 206 and an outlet 208 defined at the bottom surface 210. The bottom surface 210 is defined at the downstream end 211 of the copper nozzle 204. The molten metal 110 from the copper crucible 202 flows into the inlet 206 of the copper nozzle 204, exits through the outlet 208 of the copper nozzle 204, and flows into the atomization chamber 106.

[0040] Each copper nozzle 204 defines a plurality of grooves 212 extending from its side 214 to its bottom 210. The copper nozzle 204 defines a width W from its side 214 to the inner surface of the second cooling channel 156. Multiple atomizing fluid supply units 158, such as plasma torches, gas torches, gas pipes, manifolds, and plenums, are arranged such that the outlet 160 of each atomizing fluid supply unit 158 ​​is adjacent to one of the grooves 212. This arrangement can be called a "close coupling" of the atomizing fluid supply units 158 to the copper nozzles 204. Each atomizing fluid supply unit 158 ​​can be positioned at a distance L from the top surface of the copper crucible 202. The plurality of grooves 212 allow atomizing gases, such as the flows from each atomizing fluid supply unit 158, to feed the flow of molten metal 110 from the outlet 208 of the copper nozzles 204 into the atomizing chamber 106. As shown in Figure 5, the multiple grooves 212 can be arranged at equal intervals along the circumference of the copper nozzle 204 so that the atomizing gas flow flows evenly around the flow of molten metal 110. Although Figure 5 shows three grooves 212, it will be understood that the copper nozzle 204 may contain a different number of grooves 212, such as four, five, or six.

[0041] As shown in Figure 5, the groove 212 can be defined as an arc shape that starts from the side 214 and extends to the bottom 210, and extends along the height H. More specifically, as shown in the cutaway 162, the outlet 160 of the atomizing fluid supply unit 158 ​​is positioned so that the inlet angle of the atomizing gas flow is perpendicular to the side 214, forming a 90-degree angle. It will be understood that the inlet angle may be different from 90 degrees. The atomizing gas flows through the groove 212 past the side 214 to the bottom 210, where the outflow of the atomizing gas forms an outlet angle of X degrees with respect to the vertical axis, as shown in the cutaway 164, where X is a specified angle determined based on the specific flow path of the atomizing gas. The shape of the groove 212 can be specified to optimize the shear force of the atomizing gas supplied onto the molten metal. Due to the specified outlet angle, the atomizing gas draws the molten metal 110 into the atomizing chamber 106 through the copper nozzle 204. Specifically, the atomized gas and the molten metal 110 merge at a contact point 166 separated by a gap G from the bottom surface 210 of the copper nozzle 204.

[0042] Assembly 200 includes a cooling system 144 and an induction heater 136. As previously stated, the induction heater 136 melts the metal raw material 108 into molten metal 110, and the cooling system 144 cools the copper crucible 202 and copper nozzle 204 to maintain their rigidity. The heating coil 138 of the induction heater 136 can be operated at a specific frequency to uniformly melt the metal raw material 108. Although not shown in Figure 5, it will be understood that assembly 200 may include a second cooling system, as shown in Figure 3B, to cool the copper crucible 202 and copper nozzle 204 separately.

[0043] Next, referring to Figure 6, another assembly 300 for melting the metal raw material 108 is shown. Assembly 300 contains components similar to those of assembly 200, and common components are given common numbers.

[0044] The assembly 300 includes a copper crucible 202, a copper nozzle 204 positioned below the copper crucible 202, and an annular plate 302 positioned below the copper nozzle 204 and defining an opening 304. The annular plate 302 is positioned in the melting chamber 104 adjacent to the atomizing chamber 106 such that the opening 304 is the only connection between the melting chamber 104 and the atomizing chamber 106.

[0045] As shown in Figure 6, the copper nozzle 204 and the atomizing fluid supply unit 158 ​​are positioned above the annular plate 302. The molten metal 110 flows through the copper nozzle 204, and the atomizing fluid supply unit 158 ​​directs a gas or plasma flow from the outlet 160 along the groove 212 of the copper nozzle 204, guiding the molten metal 110 to the opening 304. The annular plate 302 separates the molten chamber 104 from the atomizing chamber 106, so when the molten metal 110 in the atomizing chamber 106 is atomized by the flow from the atomizing fluid supply unit 158, the annular plate 302 prevents at least a portion of the molten metal 110 from flowing upward and returning to the molten chamber 104. By preventing the upward flow of the molten metal 110, contact between the hot molten metal 110 and components in the molten chamber 104 that could be damaged by the molten metal 110 can be reduced or suppressed. The annular plate 302 thus helps protect the components of the molten chamber 104 by preventing metal particles from flowing upward from the atomization chamber 106. In particular, the annular plate 302 includes a tapered edge 306 that opens into the atomization chamber 106, thereby allowing the molten metal 110 to form a conical droplet flow 112 within the atomization chamber 106. Furthermore, the annular plate 302 helps to regulate the pressure difference between the molten chamber 104 and the atomization chamber 106.

[0046] The annular plate 302 includes a cooling system 308 to maintain the rigidity of the annular plate 302 while the molten metal 110 is being heated. Similar to the cooling system 144 described above, the cooling system 308 includes a controller 310, a pump 312, a storage tank 314, and a heat exchanger 316. The controller 310 operates the pump 312 to supply water from the storage tank 314 to the cooling channels 318 of the annular plate 302. The heat exchanger 316 cools the heated water (or other coolant) from the cooling channels 318 and supplies the cooled water to the storage tank 314.

[0047] As described above, the cooling system 308 can be operated to keep the temperature of the annular plate 302 below a specified temperature. The cooling system 308 for the annular plate 302 can be a separate system from the cooling system 144 for the copper crucible 202 and copper nozzle 204. Alternatively, the cooling system 308 for the annular plate 302 can share one or more components with the cooling system 144 for the copper crucible 202 and copper nozzle 204, such as by sharing a common storage tank.

[0048] The copper nozzle 204 can be separated from the annular plate 302 by a gap 320, although in certain embodiments the gap may not be necessary. The size of the gap 320 is determined based on the specified flow characteristics of the atomized gas and the molten metal 110. More specifically, the gap 320 can be sized such that the atomized gas and the molten metal 110 can meet at a specified contact point 166 through the opening 304, where droplets 112 of the molten metal 110 are formed.

[0049] Referring next to Figure 7, a flow diagram of a method 700 for melting a metal raw material according to an exemplary embodiment of the present disclosure is provided. The method 700 in Figure 7 can be used to operate one or more exemplary assemblies described above with reference to Figures 1 to 6. However, in other exemplary embodiments, the method 700 can be used additionally or alternatively to operate other suitable assemblies for heating metal.

[0050] As shown, method 700 includes, in (702), supplying a metallic raw material to a copper crucible of the assembly. As previously stated, the raw material may be in the form of a metal that can be melted in the copper crucible. The raw material may include metal powder, metal shavings, metal wire, or a combination thereof. The metal may be aluminum, titanium, or an alloy thereof.

[0051] Method 700 includes, in (704), activating a cooling system that penetrates a copper crucible and a copper nozzle positioned below the copper crucible. Since the metal raw material is heated to a temperature above the melting point of copper, the copper crucible and copper nozzle are cooled to maintain their rigidity. The cooling system may be a water cooling system through which water flows to transfer heat away from the copper crucible and copper nozzle.

[0052] Method 700, in (706), includes operating a heating coil of an induction heater to maintain the molten metal in a liquid state. The induction heater generates eddy currents in the molten metal, heating the material above the melting point of the metal. The heating coil can be operated with an alternating current of a specific frequency to provide a specific electric field that generates eddy currents. The heating coil extends around a copper crucible and a copper nozzle, maintaining the molten metal in a liquid state.

[0053] Method 700, in (708), includes flowing molten metal from a copper crucible through a copper nozzle. Since the molten metal is a liquid, it flows downward and forms a flow that exits the outlet of the copper nozzle. A heating coil maintains a specific temperature of the molten metal and ensures that this flow is at a specified flow rate.

[0054] Method 700 includes atomizing the molten metal flowing from the copper nozzle to form metal powder in (710). A fluid flow, such as a plasma flow or a gas flow, can divide the flow of molten metal to form droplets. The droplets solidify into metal powder and fall into a powder container. A fluid supply unit for atomization, such as a plasma torch, gas torch, or gas pipe, can be positioned adjacent to the copper nozzle to atomize the molten metal.

[0055] Referring next to Figure 8, a flow diagram of a method 800 for melting a metal raw material according to an exemplary embodiment of the present disclosure is provided. The method 800 in Figure 8 can be used to operate one or more exemplary assemblies described above with reference to Figures 1 to 6. However, in other exemplary embodiments, the method 800 can be used additionally or alternatively to operate other suitable assemblies for heating metal.

[0056] Method 800 includes, in (802), supplying a metallic raw material to a copper crucible. As previously stated, the raw material may be in the form of a metal that can be melted in the copper crucible. The raw material may include metal powder, metal shavings, metal wire, or a combination thereof. The metal may be aluminum, titanium, or an alloy thereof.

[0057] Method 800, in (804), includes cooling the copper crucible and copper nozzle to a temperature below a temperature threshold. Specifically, the cooling system flows water around the copper crucible and copper nozzle to maintain the temperature of the copper crucible and copper nozzle below a temperature threshold and to maintain the rigidity of the assembly.

[0058] Method 800 includes, in (806), melting the metal raw material in a copper crucible into molten metal. A heater, such as an induction coil, can raise the temperature of the raw material above the melting point of the metal. It will be understood that steps (804) and (806) can be performed simultaneously so that the cooling system and the induction heater operate at approximately the same time.

[0059] Method 800, in (808), includes flowing molten metal from a copper crucible through a copper nozzle. An induction heater heats the molten metal to a viscosity that allows for a specific flow rate.

[0060] Method 800, in (810), includes atomizing molten metal descending into the atomization chamber by flowing a gas stream from an atomizing fluid supply unit along a groove in a copper nozzle. This stream may be a low-temperature gas stream or a high-temperature gas stream from a gas heater or plasma torch. In particular, the gas stream collides with the molten metal stream. Both the gas stream and the molten metal stream flow through an opening in an annular plate located below the copper nozzle. The groove determines the position of the collision angle between the molten metal stream and the atomizing fluid stream. To apply atomization and to reduce or suppress metal scattering, it is preferable that the atomizing fluid is supplied at a downward angle with respect to the axis of symmetry of the metal delivery channel in the nozzle.

[0061] Method 800 includes atomizing the molten metal in an atomization chamber in (812). As the flow guides the molten metal into the atomization chamber, the flow divides the molten metal into droplets. The droplets cool to solid particles and settle in a powder collection container of the atomization chamber.

[0062] As previously stated, in the process of designing an atomization assembly with a copper nozzle in combination with an induction heater and cooling system, the inventors inadvertently discovered an important relationship between the mass flow rate of the metal, the mass flow rate of the coolant in the copper nozzle, the maximum surface temperature of the copper in contact with the solidified molten metal, and the maximum temperature of the molten metal passing through the outlet of the copper nozzle. This design process included, for example, designing atomization assemblies having the aforementioned structure with variations in the aforementioned aspects (mass flow rate and maximum temperature), and evaluating the overall atomization system and powder properties. This relationship can be considered an indicator of the atomization system's ability to produce metal powders of a desired fine powder size (e.g., titanium or titanium alloys) without excessively contaminating the metal being atomized or consuming the main components of the atomization system, and to enable the use of recycled materials as needed. It will be further understood that this relationship can be considered an indicator of the atomization system's ability to achieve these advantages without unnecessarily depleting energy resources (electricity to drive the induction heater and water or coolant for the cooling system).

[0063] This relationship applies to atomization assemblies having copper nozzles combined with induction heaters and cooling systems. This relationship links the mass flow rate of the metal, the mass flow rate of the copper nozzle coolant, the maximum surface temperature of the copper in direct contact with the solidified molten metal, and the maximum temperature of the molten metal passing through the outlet of the copper nozzle, as will be described in more detail later. It is important to note that this relationship applies to relatively small nozzles in the metal powder atomization process that can limit the mass flow rate of the metal, such as those with an inner diameter within the upper limit (i.e., having a diameter at the outlet).

[0064] In particular, the inventors have discovered that by including an induction heater and a cooling system in combination with a copper nozzle, it is possible to design an atomization system having a specific maximum temperature Tmetal of the metal passing through the outlet of the copper nozzle (for example, through the outlet 132 of the copper nozzle 124 in Figures 3A-3B) and a maximum temperature Tsurface of an inner surface that is in direct contact with the metal, such as the copper surface that is in direct contact with the solidified molten metal (for example, the inner surface 133 of the copper nozzle 124 in Figures 3A-3B).

[0065] The inventors have found that in order to achieve desirable flow characteristics (e.g., sufficient fluidity without excessive solidification on the copper nozzle) and without affecting the metal composition, the maximum temperature Tmetal of the metal passing through the copper nozzle outlet must be kept within a relatively narrow range. For example, if the metal is a titanium alloy containing aluminum, if the maximum temperature Tmetal exceeds an upper threshold, the aluminum may evaporate, potentially affecting the composition of the titanium alloy.

[0066] Furthermore, the inventors discovered that, in order to not only keep the copper nozzle in a solid state (assuming the metal may be heated to a temperature far exceeding the melting point of copper) but also to reduce wear on the copper nozzle so that it is not "consumed" as part of the atomization process, the maximum temperature of the copper surface in direct contact with the solidified molten metal, Tsurface, must also be kept within a relatively narrow range. Moreover, the inventors discovered that the copper nozzle can function in this way without being cooled to unnecessarily low temperatures that could make the atomization process unproductive in terms of energy consumption.

[0067] Furthermore, the inventors have discovered that by including an induction heater and a cooling system in combination with a copper nozzle, the atomization system can be designed to supply molten metal through the outlet of the copper nozzle (for example, through the outlet 132 of the copper nozzle 124 in Figures 3A-3B) at a mass flow rate of ●metal, enabling the molten metal to be atomized into a desired small powder. The atomization system can also be designed with a cooling system capable of supplying a cooling fluid through the copper nozzle at a mass flow rate of ●coolant, and the copper nozzle can be designed to receive and circulate the cooling fluid at a mass flow rate of ●coolant, thereby enabling the supply of molten metal through the outlet of the copper nozzle at a mass flow rate of ●metal without maintaining the maximum temperature Tmetal and maximum temperature Tsurface within a desired range and without overcooling the copper nozzle.

[0068] To be understood, the mass flow rate of coolant through the copper nozzle refers to the total mass flow rate of all coolant supplied to the copper nozzle at a given time.

[0069] Therefore, the relationships revealed below allow us to identify a atomization assembly combining an induction heater and cooling system with a copper nozzle that can achieve the aforementioned desirable advantages while avoiding the aforementioned pitfalls and is suitable for producing powders with a desired particle size.

[0070] The desirable relationship for providing an improved atomization system, as discovered by the inventors, is the energy conversion factor (ECF), which is expressed as follows:

number

[0071] To ensure clarity, the term "manufacturing mode" refers to the steady-state operating conditions of a milling assembly where it is producing metal powder at a rate of 70% or more of its maximum design operating speed (in kilograms per second). The term "maximum design operating speed" refers to the operating speed of the milling assembly for a particular metal at which the milling assembly produces the largest amount of powder.

[0072] The values ​​of various parameters related to ECF are listed in Table 1 below. [Table 1]

[0073] Referring here to Figures 9 and 10, the relationships between the various parameters of the ECF described above are shown according to one or more exemplary embodiments of the present disclosure. Specifically, Figure 9 shows a table containing numerical values ​​corresponding to some of the atomization assemblies plotted in Figure 10. Figure 10 is a plot of an atomization assembly according to one or more exemplary embodiments of the present disclosure, showing the ECF (Y-axis) and the mass flow rate in kilograms / second (kg / second) of the coolant supplied from one or more cooling passages of the copper nozzle (X-axis). The values ​​plotted in the chart of Figure 10 include various exemplary maximum temperatures of the copper surface in contact with the solidified molten metal, and are indicated by lines labeled as such. In particular, as also shown in the chart of Figure 10, these values ​​assume that the mass flow rate in kilograms / second (kg / second) of the molten metal passing through the outlet of the copper nozzle is 0.025 kg / second and the maximum temperature (Celsius) of the molten metal flowing through the outlet of the copper nozzle is 1700°C.

[0074] Although not shown in Figures 9 and 10, as mentioned above, this relationship applies to relatively small nozzles that can limit the mass flow rate of metal in the metal powder atomization process, for example, those whose inner diameter falls within the upper limit (i.e., have a diameter at the outlet). In some embodiments, the upper limit of the inner diameter of the metal outlet of the copper nozzle is set to 0.750 inches, thereby defining the inner diameter of the metal outlet of the copper nozzle to be 0.750 inches or less.

[0075] Furthermore, it will be understood that the above relationship is valid for various different atomization assemblies having various different operating parameters and configurations. In one exemplary embodiment, the atomization assembly may have a total plasma torch output of 100 kilowatts (kW), a total induction power of 250 kW (e.g., for induction heater 136), a mass flow rate of coolant supplied from one or more cooling passages of the copper nozzle of 3 kilograms / second (kg / second), a mass flow rate of molten metal through the outlet of the copper nozzle of 0.017 kilograms / second (kg / second), a pouring metal supply rate equal to the mass flow rate of molten metal through the outlet of the copper nozzle (0.017 kg / second), and a pressure difference of 100 mbar between the melting chamber and the reaction chamber of the atomization assembly. Such a configuration can supply powder having a particle size with a median D50 equal to 51 microns when atomizing titanium or a titanium alloy.

[0076] It will be further understood that this disclosure provides a method for atomizing metals. This method may utilize one or more of the exemplary atomization assemblies described above, or other suitable atomization assemblies.

[0077] In one exemplary embodiment, this method involves operating an atomization assembly in manufacturing mode. Operating the atomization assembly in manufacturing mode may include feeding metal into a crucible, feeding it from the crucible to a copper nozzle, feeding it through the copper nozzle to a metal outlet of the copper nozzle (e.g., outlet 132 in embodiments of Figures 3A-3B), and feeding it through the metal outlet at a mass flow rate of ●metal (kilograms / second (kg / second)). In certain exemplary embodiments, the metal may be titanium or a titanium alloy.

[0078] This method may further include cooling the copper nozzle with a cooling system while the atomization assembly is operating in manufacturing mode. Cooling the copper nozzle may include supplying a flow of cooling fluid at a mass flow rate to one or more cooling passages of the copper nozzle.

[0079] In the exemplary embodiment described above, while the atomization assembly is operating in manufacturing mode, the copper nozzle sets the maximum temperature Tsurface, the metal passing through the metal outlet sets the maximum temperature Tmetal, and the atomization assembly sets an energy conversion coefficient (ECF) between 1.4% (0.014) and 25.0% (0.25). The ECF is equal to the following formula:

number

[0080] In certain exemplary embodiments, the method may further include heating the metal in an induction heater positioned around a crucible, a copper nozzle, or both, while the atomization assembly is operating in manufacturing mode.

[0081] Further embodiments are provided by the subject matter of the following sections.

[0082] A atomizing assembly for heating a metal includes a copper crucible positioned to hold the metal, a copper nozzle extending downward from the copper crucible, a heating coil extending around the copper crucible and the copper nozzle, and a cooling system in thermal communication with at least one of the copper crucible or the copper nozzle.

[0083] The assembly described in any of the preceding sections, wherein the copper crucible includes an inlet and an outlet, the copper nozzle includes an inlet and an outlet, and the outlet of the copper crucible is positioned above the inlet of the copper nozzle.

[0084] The assembly according to any of the preceding items, further comprising an atomizing fluid supply unit positioned adjacent to the outlet of a copper nozzle.

[0085] The atomizing fluid supply unit is configured to deliver one of the following: a cryogenic gas, a high-temperature gas, or a plasma, as described in any of the preceding sections of the assembly.

[0086] The assembly described in one of the preceding sections, in which the inlet of the copper crucible is larger than the outlet of the copper nozzle.

[0087] The assembly according to any of the preceding paragraphs, wherein a copper crucible defines a first cooling channel, a copper nozzle defines a second cooling channel, and the cooling system is a water cooling system including a pump, a tank, and a heat exchanger that are in fluid communication with at least one of the first or second cooling channels.

[0088] The assembly described in any of the preceding sections, wherein the first cooling channel and the second cooling channel are in fluid communication with each other.

[0089] The assembly described in any of the preceding sections, wherein the first cooling channel is in fluid communication with a cooling system, and the second cooling channel is in fluid communication with a second cooling system.

[0090] The heating coil is configured to heat the metal to a temperature higher than the melting point of the metal, as described in any of the preceding sections.

[0091] The heating coil is continuous and extends spirally from the copper crucible to the copper nozzle, as described in any of the preceding sections.

[0092] A method for heating a metal for atomization includes supplying a metal raw material to a copper crucible, activating a cooling system that extends in thermal communication with the copper crucible and a copper nozzle located below the copper crucible, activating a heating coil to melt the metal raw material in the copper crucible into molten metal, and flowing the molten metal from the copper crucible through the copper nozzle.

[0093] The method according to any of the preceding items, further comprising cooling the copper crucible and copper nozzle to a temperature below 400°C using a cooling system.

[0094] The method according to any of the preceding items, further comprising: cooling a copper crucible and a copper nozzle to a temperature below 400°C using a cooling system; heating the metal in the copper crucible and copper nozzle (where the metal is titanium or a titanium alloy) to a temperature above the melting point of the metal using a coil; and flowing the metal in the copper crucible and copper nozzle through the outlet of the copper nozzle at a flow rate of 4.0 kg / min or less.

[0095] The method described in any of the preceding sections, further comprising operating the heating coil at a single frequency.

[0096] The method according to any of the preceding items, further comprising atomizing the molten metal flowing from a copper nozzle to form a metal powder.

[0097] The heating coil is continuous and extends around the copper crucible and copper nozzle, as described in any of the preceding sections.

[0098] The method according to any of the preceding items, further comprising heating the molten metal in a heating coil such that the flow rate of the molten metal coming out of the copper nozzle is within a specified flow rate threshold.

[0099] The method according to any of the preceding items, further comprising atomizing the molten metal by flowing plasma through it from an atomizing fluid supply unit.

[0100] The method according to any of the preceding items, further comprising circulating water through the cooling system to cool the copper crucible and copper nozzle.

[0101] The method described in any of the preceding paragraphs, wherein the metal is titanium or a titanium alloy.

[0102] A atomizing assembly for heating a metal, comprising: a copper crucible positioned to hold the metal; a copper nozzle extending downward from the copper crucible; an annular plate positioned below the copper nozzle and defining an opening; a cooling system in thermal communication with the annular plate; and an atomizing fluid supply section oriented to flow an atomizing gas to guide the metal into the opening.

[0103] The assembly according to any of the preceding items, further comprising an atomization chamber and a melting chamber positioned above the atomization chamber, wherein the annular plate is positioned within the melting chamber adjacent to the atomization chamber.

[0104] The assembly described in any of the preceding sections, wherein the copper crucible, copper nozzle, and atomizing fluid supply unit are located within the melting chamber.

[0105] The assembly described in any of the preceding sections, wherein the gas pressure in the melting chamber is higher than the gas pressure in the atomizing chamber.

[0106] The copper nozzle is an assembly as described in any of the preceding sections, comprising a bottom surface defining an outlet through which metal flows, a side surface, and a groove extending from the side surface to the bottom surface.

[0107] The assembly according to any of the preceding items, wherein the copper nozzle defines a plurality of grooves extending from its bottom surface, the plurality of grooves including the aforementioned grooves, and the plurality of grooves are arranged at equal intervals along the circumference of the copper nozzle.

[0108] The assembly according to any of the preceding items, further comprising a plurality of atomizing fluid supply units, each of which is positioned adjacent to one of a plurality of grooves.

[0109] The assembly described in any of the preceding sections, wherein the outlet of the copper nozzle is spaced apart from the opening of the annular plate by a gap.

[0110] The assembly described in any of the preceding sections further includes a heating coil positioned around a copper crucible and a copper nozzle.

[0111] The annular plate is made of copper, as described in any of the preceding sections of the assembly.

[0112] The assembly described in any of the preceding sections, wherein the annular plate defines a cooling channel, and the cooling system is a cooling system including a pump, a storage tank, and a heat exchanger that are in fluid communication with the cooling channel.

[0113] The assembly according to any of the preceding items, further comprising a cooling system in thermal communication with a copper nozzle, wherein the atomizing fluid supply unit is a plasma torch, and the atomizing gas is a plasma atomizing gas.

[0114] A method for atomizing a metal, comprising flowing molten metal from a copper crucible through a copper nozzle and through an outlet defined by the copper nozzle, and flowing a flow from an atomizing fluid supply unit to guide the molten metal from the outlet through an opening in an annular plate from the molten chamber to an atomizing chamber.

[0115] The method according to any of the preceding items, further comprising separating the molten chamber from the atomizing chamber by an annular plate, and atomizing the molten metal in the atomizing chamber with a flow from an atomizing fluid supply unit.

[0116] The annular plate prevents at least a portion of the atomized molten metal from flowing into the molten chamber, as described in any of the preceding sections.

[0117] The method according to any of the preceding items, further comprising providing a specific flow rate of molten metal exiting a copper nozzle by allowing a flow from an atomizing fluid supply unit to pass through.

[0118] The method according to any of the preceding items, further comprising activating heating coils of an induction heater positioned around a copper crucible and a copper nozzle to melt a metal raw material into a molten metal.

[0119] The method according to any of the preceding items, further comprising cooling the annular plate with a cooling system.

[0120] Cooling the annular plate is the method described in any of the preceding paragraphs, further comprising circulating water from a pump into cooling channels defined within the annular plate.

[0121] The flow from the atomizing fluid supply unit is a plasma flow, as described in any of the above sections.

[0122] A atomizing assembly for heating a metal, comprising: a copper crucible positioned to hold the metal; a copper nozzle extending below the copper crucible and defining grooves on its side, outer surface, and at its downstream end, from the side to the outer surface; a cooling system in thermal communication with the copper crucible and the copper nozzle; and an atomizing fluid supply unit including an outlet positioned adjacent to the groove.

[0123] The assembly according to any of the preceding items, further comprising an atomizing chamber and a melting chamber, wherein the melting chamber is positioned above the atomizing chamber.

[0124] The assembly described in any of the preceding sections, wherein the copper crucible, copper nozzle, and atomizing fluid supply unit are located within the melting chamber.

[0125] The assembly described in any of the preceding sections, wherein the gas pressure in the melting chamber is higher than the gas pressure in the atomizing chamber.

[0126] The copper nozzle includes a bottom surface that defines an outlet through which metal flows, and a groove extends to the bottom surface, as described in any of the preceding sections.

[0127] The assembly described in any of the preceding sections, wherein the copper nozzle defines a plurality of grooves extending from its bottom surface, and the plurality of grooves are arranged at equal intervals along the circumference of the copper nozzle.

[0128] The assembly described in any of the preceding sections further includes a heating coil extending around a copper crucible and a copper nozzle.

[0129] The coil is continuous, as described in any of the preceding sections.

[0130] The cooling system is a water-cooling system, as described in any of the preceding sections.

[0131] The atomizing fluid supply unit is a plasma torch, as described in any of the preceding sections of the assembly.

[0132] A method for atomizing a metal, comprising: supplying a metal raw material to a copper crucible; cooling the copper crucible and copper nozzle to a temperature below a temperature threshold; flowing the molten metal formed from the raw material from the copper crucible through the copper nozzle and through an outlet defined by the copper nozzle; and directing a flow from an atomizing fluid supply unit along a groove in the copper nozzle to guide the molten metal downward.

[0133] The method according to any of the preceding items, further comprising atomizing molten metal in an atomization chamber with a flow from an atomization fluid supply unit.

[0134] The method according to any of the preceding items, further comprising heating the molten metal to provide a specific flow rate of molten metal exiting a copper nozzle.

[0135] Cooling the copper crucible and copper nozzle is the method described in any of the preceding paragraphs, further comprising operating a cooling system.

[0136] The method according to any of the preceding items, further comprising operating an induction heater positioned around a copper crucible and a copper nozzle to melt the raw metal material.

[0137] The method according to any of the preceding items, further comprising directing each flow from each of a plurality of atomizing fluid supply units along each of a plurality of grooves in a copper nozzle.

[0138] The groove is provided in any of the above-mentioned methods to guide the flow from the atomizing fluid supply unit to the point of contact with the molten metal.

[0139] The method according to any of the preceding items, further comprising atomizing molten metal into droplets and forming metal powder from the droplets.

[0140] The metal is titanium, as described in any of the preceding sections.

[0141] The flow from the atomizing fluid supply unit is a plasma flow, as described in any of the above sections.

[0142] Atomization assembly comprising: a crucible configured to receive a metal which is titanium or a titanium alloy; a copper nozzle extending below the crucible and configured to receive the metal from the crucible, defining one or more cooling passages, an inner surface and a metal outlet; and a cooling system fluid-communicating with the one or more cooling passages of the copper nozzle to supply a flow of cooling fluid to the one or more cooling passages at a mass flow rate ●coolant during operation of the atomization assembly in the manufacturing mode, wherein during operation of the atomization assembly in the manufacturing mode, the copper nozzle determines the maximum temperature Tsurface of the inner surface in direct contact with the metal and the mass flow rate ●metal of the metal passing through the metal outlet, the metal passing through the metal outlet determines the maximum temperature Tmetal, and determines an energy conversion coefficient (ECF) of 1% (0.01) to 30% (0.30), wherein the ECF is equal to the following formula.

number

[0143] The atomization assembly according to any of the preceding items, wherein the maximum temperature Tsurface is 15°C or more and 400°C or less, and during operation of the atomization assembly in the manufacturing mode, the metal includes a layer of solidified metal in direct contact with the inner surface of the copper nozzle.

[0144] The atomization assembly described in any of the preceding paragraphs, wherein the maximum temperature Tmetal is 1650°C or higher and 2000°C or lower.

[0145] The atomization assembly according to any of the preceding items, wherein the mass flow rate of the metal passing through the metal outlet is 0.0016 kilograms / second (kg / second) or more and 0.067 kg / second or less, and the metal outlet of the copper nozzle has an inner diameter of 0.750 inches or less.

[0146] The atomization assembly according to any of the preceding items, wherein the mass flow rate of the cooling fluid passing through one or more cooling passages is 0.1 kilograms / second (kg / second) or more and 8 kg / second or less.

[0147] The atomization assembly according to any of the preceding items, wherein the maximum temperature Tsurface is 15°C or more and 400°C or less, the maximum temperature Tmetal is 1650°C or more and 2000°C or less, the mass flow rate ●metal of the metal passing through the metal outlet is 0.1 / 60 kilograms / second (kg / second) or more and 4.0 / 60 kg / second or less, and the mass flow rate ●coolant of the cooling fluid passing through one or more cooling passages is 0.1 kilograms / second (kg / second) or more and 8 kg / second or less.

[0148] The atomization assembly according to any of the preceding items, wherein the maximum temperature Tsurface is 50°C or more and 390°C or less, the maximum temperature Tmetal is 1650°C or more and 1900°C or less, the mass flow rate ●metal of the metal passing through the metal outlet is 0.0041 kilograms / second (kg / second) or more and 0.034 kg / second or less, and the mass flow rate ●coolant of the cooling fluid passing through one or more cooling passages is 0.18 kilograms / second (kg / second) or more and 2.1 kg / second or less.

[0149] The atomization assembly according to any of the preceding items, further comprising an induction heater positioned around the crucible, the copper nozzle, or both thereof, for controlling the temperature of the metal in the crucible, the copper nozzle, or both thereof during operation of the atomization assembly in the manufacturing mode.

[0150] The atomization assembly described in any of the preceding sections, wherein the metal is a titanium alloy.

[0151] The atomization assembly described in any of the preceding paragraphs, wherein the crucible is a copper crucible.

[0152] A method for atomizing a metal, comprising operating an atomization assembly in a manufacturing mode, wherein the metal is supplied to a crucible, supplied from the crucible to a copper nozzle, supplied through the copper nozzle to a metal outlet of the copper nozzle, supplied through the metal outlet at a mass flow rate of ●metal (kilograms / second (kg / second)), wherein the metal is titanium or a titanium alloy, the operation of the atomization assembly in the manufacturing mode, and cooling the copper nozzle with a cooling system while the atomization assembly is operating in the manufacturing mode. A method comprising cooling the copper nozzle, which includes supplying a flow of cooling fluid to one or more cooling passages of the copper nozzle at a mass flow rate of ●coolant, wherein while the atomizing assembly is operating in the manufacturing mode, the copper nozzle determines the highest temperature Tsurface of the copper surface in direct contact with the metal, the metal passing through the metal outlet determines the highest temperature Tmetal, the atomizing assembly determines an energy conversion coefficient (ECF) of 1% (0.01) to 30% (0.30), and the ECF is equal to the following formula.

number

[0153] The method according to any of the preceding items, further comprising heating the metal in an induction heater positioned around the crucible, the copper nozzle, or both, while the atomization assembly is operating in the manufacturing mode.

[0154] The method according to any of the preceding items, wherein the maximum temperature Tsurface is 15°C or more and 400°C or less.

[0155] The method according to any of the preceding items, wherein the maximum temperature Tmetal is 1650°C or higher and 2000°C or lower.

[0156] The method according to any of the preceding items, wherein the mass flow rate of the metal passing through the metal outlet is 0.0016 kilograms / second (kg / second) or more and 0.067 kilograms / second (kg / second) or less.

[0157] The method according to any of the preceding items, wherein the mass flow rate of the cooling fluid passing through one or more cooling passages is 0.1 kilograms / second (kg / second) or more and 8 kilograms / second (kg / second) or less.

[0158] The method according to any of the above items, wherein the maximum temperature Tsurface is 15°C or more and 400°C or less, the maximum temperature Tmetal is 1650°C or more and 2000°C or less, the mass flow rate ●metal of the metal passing through the metal outlet is 0.1 / 60 kilograms / second (kg / second) or more and 4.0 / 60 kg / second or less, and the mass flow rate ●coolant of the cooling fluid passing through one or more cooling passages is 0.1 kilograms / second (kg / second) or more and 8 kg / second or less.

[0159] The method according to any of the above items, wherein the maximum temperature Tsurface is 50°C or more and 390°C or less, the maximum temperature Tmetal is 1650°C or more and 1900°C or less, the mass flow rate ●metal of the metal passing through the metal outlet is 0.25 / 60 kilograms / second (kg / second) or more and 2.0 / 60 kg / second or less, and the mass flow rate ●coolant of the cooling fluid passing through one or more cooling passages is 0.18 kilograms / second (kg / second) or more and 2.1 kg / second or less.

[0160] The crucible is a copper crucible, as described in any of the preceding paragraphs.

[0161] The method according to any of the preceding items, wherein the metal includes a layer of solidified metal in direct contact with the inner surface of the copper nozzle.

[0162] This specification discloses the present disclosure, including the best mode, with reference to examples, and enables a person skilled in the art to implement the present disclosure, including the manufacture and use of any vise or system, and the execution of any method incorporating it. The patentable scope of the present disclosure is defined by the claims and may include other examples that a person skilled in the art could conceive. Such other examples are intended to be within the scope of the claims if they include components identical to, or equivalent components not significantly different from, the language of the claims.

[0163] [Additional Claims] (Note 1) A atomized assembly, A crucible configured to receive a metal that is titanium or a titanium alloy, A copper nozzle extending below the crucible and configured to receive the metal from the crucible, comprising a copper nozzle defining one or more cooling passages, an inner surface and a metal outlet, During operation in the manufacturing mode of the atomization assembly, a cooling system is provided that is in fluid communication with the one or more cooling passages of the copper nozzle in order to supply a flow of cooling fluid to the one or more cooling passages at a mass flow rate of ●coolant (hereinafter, "●" is "m" with a "·" above it), Includes, During operation of the atomization assembly in the manufacturing mode, The copper nozzle determines the maximum temperature Tsurface of the inner surface that is in direct contact with the metal and the mass flow rate of the metal passing through the metal outlet ●metal, The metal passing through the aforementioned metal outlet determines the maximum temperature Tmetal, An energy conversion coefficient (ECF) of 1% (0.01) or more and 30% (0.30) or less is defined, and the said ECF is equal to the following formula: Atomization assembly.

number

number

Claims

1. A atomized assembly, A crucible (122) configured to receive a metal which is titanium or a titanium alloy, A copper nozzle (124) extending below the crucible (122) and configured to receive the metal from the crucible (122), the copper nozzle (124) defining one or more cooling passages, an inner surface (133) and a metal outlet (128), During operation in the manufacturing mode of the atomization assembly, a cooling system (138) is fluidly communicating with the one or more cooling passages of the copper nozzle (124) to supply a flow of cooling fluid to the one or more cooling passages at a mass flow rate of ●coolant (hereinafter, "●" is "m" with a "•" above it), Includes, During operation of the atomization assembly in the manufacturing mode, The copper nozzle (124) determines the maximum temperature Tsurface of the inner surface (133) that is in direct contact with the metal, and the mass flow rate of the metal passing through the metal outlet (128), The metal passing through the metal outlet (128) determines the maximum temperature Tmetal. An energy conversion coefficient (ECF) of 1% (0.01) or more and 30% (0.30) or less is defined, and the said ECF is equal to the following formula: Atomization assembly. [Math 1]

2. The atomizing assembly according to claim 1, wherein the maximum temperature Tsurface is 15°C or more and 400°C or less, and during operation of the atomizing assembly in the manufacturing mode, the metal includes a layer of solidified metal in direct contact with the inner surface (133) of the copper nozzle (124).

3. The atomization assembly according to claim 1, wherein the maximum temperature Tmetal is 1650°C or higher and 2000°C or lower.

4. The atomization assembly according to claim 1, wherein the mass flow rate of the metal passing through the metal outlet (128) is 0.0016 kilograms / second (kg / second) or more and 0.067 kg / second or less, and the metal outlet (128) of the copper nozzle (124) has an inner diameter of 0.750 inches or less.

5. The atomization assembly according to claim 1, wherein the mass flow rate of the cooling fluid passing through one or more cooling passages is 0.1 kilograms / second (kg / second) or more and 8 kg / second or less.

6. The atomization assembly according to claim 1, wherein the maximum temperature Tsurface is 15°C or more and 400°C or less, the maximum temperature Tmetal is 1650°C or more and 2000°C or less, the mass flow rate ●metal of the metal passing through the metal outlet (128) is 0.1 / 60 kg / sec (kg / sec) or more and 4.0 / 60 kg / sec or less, and the mass flow rate ●coolant of the cooling fluid passing through one or more cooling passages is 0.1 kg / sec (kg / sec) or more and 8 kg / sec or less.

7. The atomization assembly according to claim 1, wherein the maximum temperature Tsurface is 50°C or more and 390°C or less, the maximum temperature Tmetal is 1650°C or more and 1900°C or less, the mass flow rate ●metal of the metal passing through the metal outlet (128) is 0.0041 kilograms / second (kg / second) or more and 0.034 kg / second or less, and the mass flow rate ●coolant of the cooling fluid passing through one or more cooling passages is 0.18 kilograms / second (kg / second) or more and 2.1 kg / second or less.

8. The atomizing assembly according to claim 1, further comprising induction heaters positioned around the crucible (122), the copper nozzle (124), or both thereof, for controlling the temperature of the metal in the crucible (122), the copper nozzle (124), or both thereof, during operation of the atomizing assembly in the manufacturing mode.

9. The atomization assembly according to claim 1, wherein the metal is a titanium alloy.

10. The atomization assembly according to claim 1, wherein the crucible (122) is a copper crucible (122).

11. A method for atomizing metal, Operating an atomizing assembly in a manufacturing mode, comprising supplying the metal to a crucible (122), supplying it from the crucible (122) to a copper nozzle (124), supplying it through the copper nozzle (124) to a metal outlet (128) of the copper nozzle (124), and supplying it through the metal outlet (128) at a mass flow rate of ●metal (kilograms / second (kg / second)), wherein the metal is titanium or a titanium alloy, and operating the atomizing assembly in the manufacturing mode, Cooling the copper nozzle (124) with a cooling system while the atomization assembly is operating in the manufacturing mode, comprising supplying a flow of cooling fluid to one or more cooling passages of the copper nozzle (124) at a mass flow rate of ●coolant, Includes, While the atomization assembly is operating in the manufacturing mode, the copper nozzle (124) sets the maximum temperature Tsurface of the copper surface in direct contact with the metal, and the metal passing through the metal outlet (128) sets the maximum temperature Tmetal. The atomization assembly has an energy conversion coefficient (ECF) of 1% (0.01) or more and 30% (0.30) or less, and the ECF is equal to the following formula: method. [Math 2]

12. The method according to claim 11, further comprising heating the metal in an induction heater positioned around the crucible (122), the copper nozzle (124), or both thereof, while the atomization assembly is operating in the manufacturing mode.

13. The method according to claim 11, wherein the maximum temperature Tsurface is 15°C or more and 400°C or less.

14. The method according to claim 11, wherein the maximum temperature Tmetal is 1650°C or higher and 2000°C or lower.

15. The method according to claim 11, wherein the mass flow rate of the metal passing through the metal outlet (128) is 0.0016 kilograms / second (kg / second) or more and 0.067 kilograms / second (kg / second) or less.

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