PRODUCTION AND USE OF GRAPH-COPPER COMPOSITE POWS

Abstract

Method (300) comprising: providing (302) an inert environment; introducing (304) a first mist (120) into the inert environment using a first electrospray nozzle (116A), wherein the first mist (120) is atomized copper (204) with a negative charge; introducing (304) a second mist (122) into the inert environment using a second electrospray nozzle (116B), wherein the second mist (122) comprises graphene flakes (202) with a positive charge; and mixing (306) the first mist (120) and the second mist (122) in the inert environment to produce a graphene-copper composite powder (101).

Description

INTRODUCTION

[0001] The disclosure relates to the field of composite powders and in particular to systems and methods for producing and using graphene-copper composite powders for use in additive manufacturing or in conventional powder metallurgical processes.

[0002] Graphene-copper composites can be used as conductors in various applications, such as battery-electric vehicles. Graphene-copper powders produced by mechanical mixing, e.g., by ball milling, can damage the graphene and lead to copper oxidation. This impairs the desired properties of graphene and its coupling effect with copper. Therefore, there is a need in engineering for mixing graphene-copper powders in a way that avoids potential powder damage. SUMMARY

[0003] It is desirable to mix copper particles and graphene flakes without irreversibly altering the graphene flakes. It is also desirable to prevent the oxidation of the copper particles during the formation of the composite powder and its use in manufacturing a composite component. Furthermore, it is desirable to optimize the contact between the copper particles and the flat surfaces of the graphene flakes.

[0004] Systems, methods, and devices according to the present disclosure optimize the formation of graphene-copper composite powders by mixing a first mist comprising copper particles and a second mist comprising unaffected graphene flakes in an inert environment. The first and second mists are supplied with opposite charges such that, upon mixing, the copper particles in the first mist are attracted to the planar surfaces of the graphene flakes in the second mist. Advantageously, this contact optimizes the electrical properties of the graphene-copper composite powder. Since the supplied charges and the method do not irreversibly damage the graphene flakes, the material and electrical properties of the graphene-copper composite powder, as well as the material's behavior, are more predictable and exhibit lower tolerances and deviations.

[0005] The graphene-copper composite powder can be sorted into a variety of fractions exhibiting known particle size distributions with known surface area or volume fractions of graphene flakes and copper particles. Each fraction can then be used in further processes, such as additive manufacturing. Advantageously, the optimized contact between the flat surfaces of the graphene flakes and the copper particles reduces the formation of gaps that arise when the copper particles only touch the edges of the graphene flakes, thus optimizing the material and electrical properties of the resulting graphene-copper composite parts.

[0006] According to the aspects of the present disclosure, a process comprises providing an inert environment, introducing a first mist into the inert environment, introducing a second mist into the inert environment, and mixing the first and second mists in the inert environment to produce a graphene-copper composite powder. The first mist is formed from atomized copper with a negative charge, and the second mist comprises graphene flakes with a positive charge.

[0007] According to further aspects of the present disclosure, the process further comprises separating the graphene-copper composite powder into a plurality of fractions within the inert environment using at least one mesh sieve.

[0008] According to further aspects of the present disclosure, the method also includes feeding a first portion from the plurality of portions into a device connected to the inert environment for additive manufacturing.

[0009] According to further aspects of the present disclosure, the first mist is formed from molten copper, which is directed into the inert environment through a high-pressure nozzle.

[0010] According to further aspects of the present disclosure, a process pressure of the inert environment includes a vacuum.

[0011] According to further aspects of the present disclosure, the copper particles of the graphene-copper composite powder are formed from copper nanoparticles.

[0012] According to further aspects of the present disclosure, the graphene flakes are formed by electrochemical exfoliation.

[0013] According to further aspects of the present disclosure, the process also includes forming a graphene-copper composite rail from the composite powder by means of additive manufacturing or a conventional powder metallurgy process.

[0014] According to further aspects of the present disclosure, the process also includes forming a graphene-copper composite heat sink from the composite powder by additive manufacturing or a conventional powder metallurgy process.

[0015] According to the aspects of the present disclosure, a system comprises a chamber containing an inert environment, a first nozzle configured to introduce a first mist into a mixing section of the inert environment, a second nozzle configured to introduce a second mist into the mixing section of the inert environment, and an outlet configured to discharge a graphene-copper composite powder from the inert environment. The graphene-copper composite powder is formed by mixing the first mist of negatively charged, atomized copper and the second mist of positively charged graphene flakes. The first mist is formed from negatively charged atomized copper, and the second mist comprises positively charged graphene flakes.

[0016] According to further aspects of the present disclosure, the system further comprises at least one mesh sieve designed to separate the graphene-copper composite powder into a plurality of fractions in the inert environment.

[0017] According to further aspects of the present disclosure, the first nozzle is a high-pressure nozzle.

[0018] According to further aspects of the present disclosure, the copper particles of the graphene-copper composite powder are formed from copper nanoparticles.

[0019] According to further aspects of the present disclosure, the system also comprises a forming device designed to form a graphene-copper composite heat sink from the graphene-copper composite powder via an additive manufacturing process or a conventional powder metallurgical process.

[0020] According to further aspects of the present disclosure, the system also comprises a forming device designed to form a graphene-copper composite rail from the graphene-copper composite powder by means of additive manufacturing or a conventional powder metallurgy process.

[0021] According to aspects of the present disclosure, a graphene-copper composite powder is formed by providing an inert environment, introducing a first mist into the inert environment, introducing a second mist into the inert environment, and mixing the first and second mists within the inert environment to produce a graphene-copper composite powder. The first mist is formed from atomized copper with a negative charge, and the second mist comprises graphene flakes with a positive charge.

[0022] According to further aspects of the present disclosure, the graphene-copper composite powder is a fraction from a plurality of fractions which are separated using at least one mesh sieve in the inert environment.

[0023] According to further aspects of the present disclosure, the first mist is formed from molten copper, which is directed into the inert environment through a high-pressure nozzle.

[0024] According to further aspects of the present disclosure, the copper particles of the graphene-copper composite powder are formed from copper nanoparticles.

[0025] According to further aspects of the present disclosure, the graphene flakes are formed by electrochemical exfoliation.

[0026] The above features and advantages, as well as other features and advantages of the present disclosure, are readily apparent from the following detailed description of the best ways of carrying out the disclosure in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings are for illustrative purposes only and are not intended to limit the subject matter defined by the claims. Exemplary aspects are discussed in the following detailed description and shown in the accompanying drawings, which: Fig. 1 represents an example of a system for producing a graphene-copper composite powder; Fig. 2 represents an example of a graphene-copper composite powder; Fig. 3 represents a process for producing the graphene-copper composite powder; Fig. 4 represents an example of a device for additive manufacturing; Fig. 5 represents a schematic procedure for producing a graphene-copper composite part from the graphene-copper composite powder; Fig. Figure 6A shows a schematic first view of a graphene-copper composite heat sink; Fig. 6B a schematic second view of the composite heat sink of Fig. 6A represents; Fig. 7 represents a battery cell that uses graphene-copper composite current collectors; and Fig. This represents 8 graphene-copper composite rails for use with an electric motor. DETAILED DESCRIPTION

[0028] Fig. Figure 1 represents an example of a system for producing a graphene-copper composite powder 101. The system comprises a chamber 102, a copper feed material 104, a graphene feed material (not shown), a mixing section 105, a separation section 106, and a graphene-copper composite powder outlet 108. The chamber 102 comprises an inert environment that can be conditioned by a vacuum source 110, an inert gas inlet 112, an inert gas outlet 114, and temperature control devices (not shown).

[0029] The vacuum source 110 is designed to extract air from the inert environment during startup. The vacuum source 110, or another vacuum source, can further be designed to maintain the inert environment at a desired process pressure, either alone or in combination with other devices.

[0030] An inert gas flows through system 100 to prevent the oxidation of the powder and its particles. The inert gas enters chamber 102 via inert gas inlet 112 and exits chamber 102 via inert gas outlet 114. The flow of the inert gas can further be configured to influence or generate the desired gas flow patterns within the system. For example, inert gas inlet 112 can be located below separation section 106 and inert gas outlet 114 can be located above separation section 106, so that the flow of the inert gas promotes the movement of the graphene-copper composite powder 101 to aid in the size separation of the graphene-copper composite powder 101 (e.g., by promoting the fluidization of the graphene-copper composite powder 101).

[0031] The temperature control devices are designed to heat and / or cool the inert environment to a desired temperature profile. This temperature profile can be a uniform temperature, multiple zones with different temperatures, a temperature gradient, a combination thereof, or similar. In some aspects, the temperature profile is generated by controlling the temperatures of the input materials, the distance between components, and the insulation or thermal conductivity of the system chamber 102.

[0032] Copper and graphene are fed into the mixing section 105 of the system through the respective spray nozzles 116. The copper and graphene are supplied with opposite charges. Without being bound by theory, it is assumed that the supply of oppositely charged particles promotes both the contact between the copper particles and the graphene flakes and the packing of the resulting graphene-copper composite powder 101. In some aspects, the nozzles 116 can include one or more high-pressure nozzles. Additionally or alternatively, the nozzles 116 can include one or more electrospray nozzles.

[0033] Furthermore, the amount of charge imparted to the particles is selected to reduce voids in the resulting powder and the parts formed from it. For example, only a portion of the copper particles can be charged, so that the charged particles are attracted to the graphene flakes, while the uncharged particles reduce the repulsive forces that can leave voids in a resulting powder or additive manufacturing process. Additionally or alternatively, residual charges can be removed by grounding after mixing (e.g., by grounding the mesh sieves 124).

[0034] A first nozzle 116A is connected to the copper starting material 104, for example, a deoxidized copper melt 118. The first nozzle 116A is designed to produce a negatively charged, atomized copper mist 120 with a desired particle size distribution. The copper particles in the atomized copper mist 120 can, for example, be nanoparticles. In some aspects, the diameter of the copper particles corresponds approximately to the lateral flake size of the graphene particles. Without being bound to the theory, it is assumed that this provides improved copper-copper interfaces. Alternatively, the diameter of the copper particles is an order of magnitude smaller than the lateral flake size of the graphene particles. Again, without being bound to the theory, it is assumed that this provides improved copper-copper and graphene-copper interfaces.In other aspects, the diameter of the copper particles is two orders of magnitude smaller than the lateral flake size of the graphene particles. Without being bound to the theory, it is assumed that this provides improved graphene-copper interfaces.

[0035] A second nozzle 116B is connected to the graphene starting material. The second nozzle 116B is configured to generate a positively charged graphene mist 122. The graphene starting material comprises pure graphene flakes in a solvent. The graphene flakes are dimensioned to exhibit the desired mechanical, electrically conductive, and / or thermally conductive properties of the resulting graphene-copper composites. The graphene flakes can be single-layer and / or multi-layered. In some cases, the graphene flakes are formed by electrochemical exfoliation techniques. In some examples, the average lateral diameter of the graphene flakes is between 10 nm and 10 µm.

[0036] The solvent is selected to avoid negative interactions with the copper mist 120. For example, the solvent is chosen to prevent oxidation of the copper particles, flocculent formation, or undesirable particle shape. The solvent is also selected so that it is not present in the resulting powder under the process conditions. The solvent may be polar solvents such as alcohols (e.g., methanol or ethanol) and / or nonpolar solvents such as medium- to long-chain hydrocarbons (e.g., gasoline or kerosene).

[0037] The copper mist 120 and the graphene mist 122 are combined in the mixing section 105 of the inert environment. The mixing section 105 is designed to create a homogeneous mixture of the two mists. For example, the nozzles 116 can be distributed over the mixing section 105 such that the turbulence caused by the sprayed mist provides a homogeneous mixture of the copper particles and graphene flakes. Additionally or alternatively, the flow of the inert gas can be controlled to improve the mixing of the mist. For example, the mixing can be improved by selecting the positions of the inert gas inlet 112 and the inert gas outlet 114, the inert gas flow rate, the positioning of flow control features (e.g., baffles, formers, and turbulators), combinations thereof, etc.

[0038] After the two fogs have homogeneously mixed, the graphene-copper composite powder 101 settles on the separation section 106 of the inert environment.

[0039] The separation section 106 can, for example, comprise a plurality of mesh screens 124. The mesh screens 124 are arranged such that the graphene-copper composite powder 101 is filtered through a first mesh screen 124A, which has larger opening sizes than a subsequent mesh screen 124B, so that the graphene-copper composite powder 101 is separated into a plurality of fractions 126 with known and unique particle size distributions. Each of the plurality of fractions 126 can be selected for a specific use. For example, one of the fractions 126C can be selected for an additive manufacturing process, another fraction 126B can be further processed for another use, and another fraction 126A can be processed to remove impurities and recycled back into the copper melt 118.

[0040] In some examples, the graphene-copper composite powder 101 comprises one or more parts of 126 between 1 wt% and 40 wt% graphene. In other examples, the graphene-copper composite powder 101 comprises one or more parts of 126 between 5 wt% and 30 wt% graphene. In still other examples, the graphene-copper composite powder 101 comprises one or more parts of 126 between 10 wt% and 20 wt% graphene. Advantageously, optimal tensile strength and electrical properties can be achieved with a graphene-copper composite powder containing graphene flakes with an average lateral flake diameter of 2 µm and a content of 10 wt.%, an average lateral flake diameter of 5 µm and a content of 15 wt.%, or an average lateral flake diameter of 7 µm and a content of 20 wt.%.The advantage is that by reducing the average lateral flake diameter, the required amount of graphene in the resulting powder is generally reduced.

[0041] In some aspects, the system is coupled with a device for additive manufacturing, such as the one described with reference to Fig. The device described in section 4 below. The graphene-copper composite powder output 108 can couple the devices such that they comprise a common inert environment for one or more desired fractions 126 of the powder, which are conveyed directly from the system to the additive manufacturing device. Additionally or alternatively, the fractions 126 can be conveyed into a container in the inert environment, which can then be sealed, removed from the inert environment, transported to the additive manufacturing device, and opened / controlled for use in an inert environment of the additive manufacturing device.

[0042] Fig. Figure 2 shows an example of a graphene-copper composite powder 101 produced by the system. As can be seen, the graphene flakes 202 are distributed over the copper particles 204. Without being bound to the theory, it is assumed that electrostatic or transferred charges improve the contact between the copper particles 204 and the flat surfaces of the graphene flakes 202, thereby reducing or eliminating gaps in the powder that would otherwise arise because the copper particles 204 only touch the edges of one or more graphene flakes 202.

[0043] The avoidance of gaps and the optimized contact between the copper particles 204 and the graphene flakes 202 improve the electrical conductivity, thermal conductivity, and mechanical properties of the parts manufactured from the graphene-copper composite powder 101. Without being bound by theory, it is further assumed that the charges can be chosen to utilize the different electronic properties of the planar and edge sections of the graphene flakes 202, thereby further optimizing the packing and other physical properties of the powder, as well as the properties of the parts formed from the powder. Advantageously, mixing the charged particles also increases the graphene charge of the graphene-copper composite powder 101. For example, a graphene-copper composite powder formed by mixing charged particles can have a graphene charge of between 30 vol.-% and 40 vol-%, which is above the expected charge of 20 vol% to 25 vol% when the same particles are mixed without charges.

[0044] Fig. Figure 3 describes a process 300 for preparing a graphene-copper composite powder 101. In step 302, the process includes providing an inert environment. A first mist, e.g., atomized copper particles 204, and a second mist, e.g., graphene flakes 202 in a solvent, are introduced into the environment in step 304. The first mist and the second mist are provided with opposite charges such that, upon mixing, the copper particles 204 in the first mist are attracted to the flat surfaces on the graphene flakes 202 in the second mist. The process 300 further includes mixing the first mist and the second mist to prepare the graphene-copper composite powder 101 in step 306.The process 300 can also include an optional step 308 for filtering the produced powder into a plurality of fractions 126 with known particle size distributions and known area fractions or volume fractions of graphene flakes 202 and copper particles 204. It is conceivable that the area fractions or volume fractions can be different for each of the plurality of fractions.

[0045] Fig. Figure 4 represents an example of an additive manufacturing device 400. The additive manufacturing device 400 is designed to form parts using the graphene-copper composite powder 101 in a layer-by-layer process. The additive manufacturing device 400 comprises a sintering device 402, a chamber 404, a powder feeder 406, and a powder bed 408. The chamber 404 comprises an inert environment.

[0046] The sintering device 402 is configured to selectively form coherent sections within the graphene-copper composite powder 101 when the graphene-copper composite powder 101 is exposed to the sintering device 402. The selective formation of coherent sections produces a graphene-copper composite part 410, such that the improved contact between the graphene flakes 202 and the copper particles 204 of the graphene-copper composite powder 101 is maintained in the resulting graphene-copper composite part 410.

[0047] In the figure shown, the sintering device 402 is an electron gun 412 that emits an electron beam 414. The electron beam 414 is shaped and directed onto a focal point corresponding to an upper surface 416 of the powder bed 408 such that the electron beam 414 fuses a volume of the graphene-copper composite powder 101 to produce a layer of the resulting graphene-copper composite part 410.

[0048] The same inert gas as in the system or a different inert gas can be used in the inert environment. Additionally or alternatively, the inert environment can be an ultra-low-pressure environment. Furthermore, chamber 404 includes the powder feed 406 and the powder bed 408 in the inert environment.

[0049] The powder feeder 406 is designed to hold the graphene-copper composite powder 101 in an inert environment and feed it to the additive manufacturing device 400 for use in the powder bed 408. The illustrated powder feeder 406 is a container located in the inert environment of the chamber 404; however, it is conceivable that the container or another conveying mechanism could be connected to the outside of the chamber 404 without exposing the graphene-copper composite powder 101 to a non-inert environment.

[0050] The powder bed 408 comprises a platform 418 that is movable relative to the sintering device 402. In the illustrated embodiment, the platform 418 is configured to move three-dimensionally using a Cartesian coordinate system. Other systems can also be used. The powder bed 408 is configured to include a quantity of the graphene-copper composite powder 101 that moves with it.

[0051] Fig. Figure 5 presents a schematic process 500 for producing a graphene-copper composite part 410 from the graphene-copper composite powder 101. The process 500 begins in step 502 with feeding a quantity of the graphene-copper composite powder 101 onto a substrate. Subsequently, in step 504, the quantity of the graphene-copper composite powder 101 is prepared for sintering. The preparation may, for example, include drying the quantity of the graphene-copper composite powder 101, bringing the quantity of the graphene-copper composite powder 101 to a predetermined temperature or temperature profile, and / or treating an area 416 of the graphene-copper composite powder 101 to improve sintering or exposure to the sintering device 402. The surface treatment may, for example, B. include chemical or mechanical treatment.

[0052] Step 506 of the process 500 comprises exposing the surface 416 of the powder bed 408 relative to the sintering device 402 while the powder bed 408 is displaced. The powder bed 408 is displaced in one or more dimensions and at one or more speeds such that the sections of the graphene-copper composite powder 101 exposed to the sintering device 402 form one or more features of a cross-sectional layer of the emerging part.

[0053] After the desired features of the layer have been formed, step 508 of process 500 determines whether the part is complete. If the part is not complete, the platform 418 is moved so that another layer of the resulting part can be formed and bonded to the previous layer. Process 500 then repeats steps 502, 504, and 506 by applying another quantity of the graphene-copper composite powder 101 to the substrate above the previous layer, preparing the graphene-copper composite powder 101 for sintering, and exposing the respective layer to the sintering device 402 while the powder bed 408 is moved to form one or more features of the respective cross-sectional layer. This is repeated until all desired features of all desired layers of the workpiece have been formed.

[0054] Optionally, step 510 of process 500 can include further processing or treatment of the formed part to produce a finished graphene-copper composite object with the desired mechanical, thermal, and / or electronic properties. For example, hot pressing or annealing can be used to optimize adhesion between the layers and / or to optimize grain boundaries and other material properties of the formed part. Additionally or alternatively, the substrate can be a sacrificial substrate that is removed from the formed part by mechanical processes, chemical treatments, heat or light exposure, combinations thereof, and the like.

[0055] Fig. 6A and Fig. 6B represent a graphene-copper composite heat sink 600, which was manufactured using the method of Fig. 5 is manufactured. The graphene-copper composite heat sink 600 comprises a base 602 and a plurality of fins 604, which are designed to increase the heat flow from a heat-generating object. The base 602 is designed to contact the heat-generating object and conduct the heat from the heat-generating object to the plurality of fins 604. The fins 604 are designed to increase the surface area of ​​the graphene-copper composite heat sink 600 that is exposed to the coolant (such as air or liquids). The ribs 604 can be formed from a shaped block of the graphene-copper composite material during the additive manufacturing process or by subtractive processes (e.g. milling) without negatively affecting the target properties of the graphene-copper composite heat sink 600 provided by the graphene-copper composite powder 101.Advantageously, the graphene-copper composite heat sink 600 optimizes the cooling of the heat-generating part by optimizing the grain properties (e.g., by preventing grain growth through high-temperature operation and / or interactions with electromagnetic fields) and the thermal conductivity of the graphene-copper composite heat sink 600.

[0056] Fig. Figure 7 represents a battery cell 700 that uses graphene-copper composite current collectors 702. The battery cell 700 includes a separator 704, which is arranged between a first electrode 706 and a second electrode 708. The separator 704 allows ion transfer but prevents electronic transfer through it.

[0057] The first electrode 706 is configured to intercalate ions while the battery cell 700 is being charged and to deintercalate ions while the battery cell 700 is being discharged. The first electrode 706 is arranged on a first graphene-copper composite current collector 702. The first graphene-copper composite current collector 702 is configured to collect free electrons and move them via an external circuit between the first electrode 706 and the second electrode 708. The external circuit can include an external device, which may be a load that consumes electrical current from the battery cell 700, and / or a power source that supplies electrical current to the battery cell 700.

[0058] The second electrode 708 is configured to intercalate the ions received from the first electrode 706 when the battery cell 700 is discharged, and to deintercalate the ions for transport to the first electrode 706 when the battery cell 700 is charged. The second electrode 708 comprises a second electroactive material (not shown) and is arranged on a second graphene-copper composite current collector 702. The second electroactive material is formed from materials that interact with the first electroactive material to facilitate the flow of ions and electrons between the first electrode 706 and the second electrode 708.

[0059] The second graphene-copper composite current collector 702 is designed to collect free electrons and move via the external circuit between the first electrode 706 and the second electrode 708. The second electrode 708 may also include a binder (not shown). In some aspects, the binder of the second electrode 708 is the binding agent.

[0060] Each of the first electrode 706, the second electrode 708, and the separator 704 can further comprise an electrolyte. The electrolyte is designed to promote the movement of ions between the first electrode 706 and the second electrode 708 during the charging and discharging of the lithium-ion cell. The electrolyte can be a liquid, a solid, or a gel electrolyte.

[0061] Fig.Figure 8 represents graphene-copper composite busbars 802 for use with an electric motor. Each graphene-copper composite busbar 802 includes a coupler 804 configured to be electrically connected to a power source. The graphene-copper composite busbars 802 are attached to the windings (not shown) of the electric motor, so that the current between the power source (not shown) and the windings is conducted via the graphene-copper composite busbars 802. Advantageously, the improved mechanical properties of the graphene-copper composite busbars 802 optimize the performance of the graphene-copper composite busbars 802 by avoiding the effects on the material properties of pure copper busbars that result from resistance heating generated during use.The improved thermal conductivity of the 802 graphene-copper composite busbars also optimizes the transfer of heat generated in the windings away from the motor, increasing operating efficiency, maintaining the desired material properties of the copper windings, and extending the service life of the electric motor. For example, the electric motor can generate an electromagnetic field with a temperature between 50 °C and 100 °C. This can occur during short cycles, extended operation, and combinations thereof. The 802 graphene-copper composite busbars optimize the material's microstructure and prevent grain growth and / or busbar softening, which can occur with other materials. These optimized mechanical properties and improved durability also allow for the integration of heat transfer channels into the 802 graphene-copper composite busbars to further enhance electric motor operation.

[0062] Although the present disclosure discusses additive manufacturing using the graphene-copper composite powder 101, it is also considered that other powder metallurgy forming devices and techniques can be used to produce graphene-copper composite parts using the graphene-copper composite powder 101.

[0063] The foregoing detailed description is merely exemplary and is not intended to limit application and use. Furthermore, there is no intention to be bound by the express or implied theory set forth in the preceding sections or the preceding detailed description.

[0064] As those skilled in the art know, the present disclosure is suitable for various modifications and alternative forms, and some representative embodiments are illustrated by way of example in the drawings and described in detail above. It is understood, however, that the novel aspects of this disclosure are not limited to the particular forms illustrated in the accompanying drawings. Rather, the disclosure is intended to cover modifications, equivalents, combinations, sub-combinations, substitutions, groupings, and alternatives that fall within the scope and spirit of the disclosure and are defined by the accompanying claims.

[0065] Unless the context clearly indicates otherwise, the words "and" and "or" apply in both the subjunctive and disjunctive moods; the word "all" means "all and every", the word "every" means "all and every"; the word "including" means "including and without restriction"; and the singular forms "a", "an", as well as "the", "the" include the plural forms and vice versa.

[0066] Unless expressly stated otherwise, or in light of the context, including the appended claims, numerical values ​​of parameters (e.g., of quantities or conditions) in this description are to be understood as being modified by the term "approximately," regardless of whether "approximately" actually precedes the numerical value. The numerical parameters specified here and in the appended claims are approximate values ​​that may vary depending on the desired properties to be achieved by the present disclosure. At a minimum—and not as an attempt to limit the application of the equivalence doctrine to the scope of the claims—each numerical parameter should be interpreted with respect to the number of significant figures reported and using standard rounding methods.

[0067] Words of approximation such as "approximately", "about", "essentially" and the like may be used here in the sense of "at, close or almost at", "within 0-10% of" or "within acceptable manufacturing tolerances" or a logical combination thereof.

[0068] While the measure and limits of the term "approximately" are readily understood by a person skilled in the art, the term "approximately" indicates that the stated numerical value or property is subject to inaccuracies. Unless otherwise understood in the field, the inaccuracy implied by "approximately" is understood differently in this ordinary sense, meaning that "approximately" indicates at least deviations that may arise from ordinary methods of measurement and the use of such parameters. For example, unless otherwise understood in the field, the term "approximately" means that the stated value will deviate by no more than 10% (e.g., ±10%).

[0069] While the measure and limits of the term "essentially" are readily understood by a person skilled in the art, the term "essentially" indicates that the stated numerical value or property allows for a certain degree of inaccuracy. If the inaccuracy implied by "essentially" is not understood differently in this ordinary sense within the field, then "essentially" at least refers to deviations that may arise from manufacturing processes and the measurement of such parameters. If not understood differently within the field, the term "essentially" means, for example, that the stated value will not deviate from the stated value by more than 5% (e.g., ±5%).

[0070] While the measure and limits of the term "essentially" are readily understood by a person skilled in the art, the term "essentially" indicates that the stated numerical value or property permits a slight inaccuracy. If the inaccuracy implied by "essentially" is not understood differently in the field in this ordinary sense, then "essentially" at least indicates negligible deviations in the desired parameters that may not be surmountable. If not understood differently in the field, the term "essentially" means, for example, that the stated value will not deviate from the specified value by more than 1% (e.g., ±1%).

[0071] While the measure and limits of the term "pure" are readily understood by a person skilled in the art, the term "pure" indicates that the compound may contain very small traces of other substances. If the imprecision implied by "pure" is not otherwise understood in this ordinary sense within the scientific community, then "pure" at least denotes the deviations that can arise from separation processes and the measurement of such parameters. If not otherwise understood within the scientific community, the term "pure" means, for example, more than 99.9% of the specified material.

[0072] While the best modes for carrying out the disclosure have been described in detail, those who are familiar with the technology to which this disclosure relates will recognize various alternative designs and embodiments for carrying out the disclosure within the scope of the attached claims. legend

[0073] In the drawing figures, N stands for no and Y for yes.

Claims

[1] Method comprising: Providing an inert environment; Introducing a first mist into the inert environment, the first mist being atomised copper with a negative charge; introducing a second mist into the inert environment, the second mist comprising graphene flakes with a positive charge; and Mixing the first mist and the second mist in the inert environment to thereby produce a graphene-copper composite powder. [2] The method of claim 1, further comprising separating the graphene-copper composite powder into a plurality of fractions within the inert environment using at least one mesh screen. [3] The method of claim 2, further comprising feeding a first portion of the plurality of portions into an additive manufacturing device connected to the inert environment. [4] The method of claim 1, wherein the first mist is formed from molten copper which is passed through a high pressure nozzle into the inert environment. [5] The method of claim 1, wherein the process pressure of the inert environment comprises a vacuum. [6] The method according to claim 1, wherein copper particles of the graphene-copper composite powder are formed from copper nanoparticles. [7] The method of claim 1, further comprising forming a graphene-copper composite rail from the composite powder by an additive manufacturing process or a conventional powder metallurgy process. [8] The method of claim 1, further comprising forming a graphene-copper composite heat sink from the composite powder by an additive manufacturing process or a conventional powder metallurgy process. [9] System comprising: a chamber comprising an inert environment and a mixing section, the mixing section being disposed within the inert environment; a first nozzle and a second nozzle, wherein the first nozzle is configured to introduce a first mist into the mixing section of the inert environment, the first mist being formed of atomized copper and having a negative charge, and wherein the second nozzle is configured to introduce a second mist into the mixing section of the inert environment, the second mist comprising graphene flakes and having a positive charge; and an exit configured to deliver a graphene-copper composite powder from the inert environment, wherein the graphene-copper composite powder is formed by mixing the first mist of negatively charged atomized copper and the second mist of positively charged graphene flakes. [10] Graphene-copper composite powder formed by: Providing an inert environment; Introducing a first mist into the inert environment, the first mist being atomised copper with a negative charge; introducing a second mist into the inert environment, the second mist comprising graphene flakes with a positive charge; and Mixing the first mist and the second mist in the inert environment to thereby produce a graphene-copper composite powder.

Images