Process for mass production of vehicle components made of graphene composite material

Abstract

A method for mass-producing vehicle components made of graphene composite material is provided. The method comprises injecting a first flux into a molten metal contained in a furnace using a first flux injection system and injecting a graphene flux into the molten metal using a second flux injection system. The method comprises stirring and homogenizing the molten metal and the graphene flux in the furnace using an agitator. The method comprises transferring the molten metal into a mold having an electromagnetic stirring system and then stirring the molten metal with the electromagnetic stirring system until the molten metal solidifies. The electromagnetic stirring system ensures homogenization of the molten metal and the graphene flux.

Description

INTRODUCTION

[0001] The present disclosure relates to the field of graphene composites, and more particularly to casting methods for forming a mass-produced graphene composite having a uniformly distributed graphene matrix within the composite. For general technical background, reference is made to US 2021 / 0 062 304 A1, CN 1 15 007 830 A, CN 1 08 060 321 A, CN 1 09 402 442 A, and CN 1 16 356 193 A.

[0002] Aluminum and aluminum alloys are used as thermal conductors in many components, such as electric vehicle battery packs. Batteries and other vehicle components generate heat in vehicle battery packs, which must be dissipated to prevent overheating. Furthermore, battery pack components are subject to stress and must be structurally sound. Battery pack components made of pure grade 1xxx aluminum and aluminum alloys are subject to grain growth at elevated operating temperatures (50°C–100°C) and during long-term operation. Furthermore, copper and copper alloys are used as electrical conductors in many components.

[0003] While current components made of aluminum and aluminum alloys, as well as copper and copper alloys, fulfill their intended purpose of being thermally and electrically conductive and providing structural strength and stability, there is still a need for components, as well as processes and systems for manufacturing the components, that exhibit increased thermal and electrical conductivity, structural strength and thermal material stability. SUMMARY

[0004] The method according to the invention is defined by the features of the accompanying independent main claim. Advantageous further developments can be found in the following description and the dependent claims.

[0005] Preferably, the method comprises blowing in nitrogen gas and / or argon during degassing and blowing in of the first flux.

[0006] Preferably, the method comprises injecting graphene with a surface treatment of nickel, which is deposited on the graphene when the graphene flux is injected into the molten metal.

[0007] Preferably, the method comprises injecting graphene premixed with graphene-aluminum powder and / or graphene-copper powder when injecting the graphene flux into the molten metal.

[0008] Preferably, the method comprises using a propeller stirrer to stir and homogenize the molten metal.

[0009] According to several aspects of the present disclosure, a method for cooling components used in electric vehicles is provided. The method includes injecting a first flux into a molten metal in a furnace using a first flux injection nozzle. The first flux comprises nitrogen gas and / or argon, and the molten metal is degassed by the first flux. The method includes injecting a graphene flux into the molten metal using a second flux injection nozzle. The graphene flux is a powder, and the graphene flux has a surface treatment comprising nickel and / or copper. The method includes stirring and homogenizing the molten metal and the graphene flux in a furnace using a propeller stirrer. The method further includes transferring the molten metal into a mold having an electromagnetic stirring system.The electromagnetic stirring system ensures the homogenization of the molten metal and the graphene flux. The process further includes stirring the molten metal with the electromagnetic stirring system until the molten metal solidifies at a temperature of less than or equal to 660 °C, and forming a cooling component for an electric vehicle from the cooled molten metal. The cooling component includes a cooling plate for the vehicle's battery pack.

[0010] Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are for purposes of illustration only and are not intended to limit the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The drawings described herein are for illustrative purposes only and are not intended to limit the scope of the present disclosure in any way. Fig. 1 shows a simplified schematic view illustrating a furnace system for receiving and homogenizing a graphene-containing molten metal according to the present disclosure. Fig. Figure 2 shows a simplified schematic view illustrating a high pressure die casting (HPDC) designed to discharge the molten metal from the Fig. 1, according to the present disclosure. Fig. Figure 3A shows a simplified schematic view showing an open mold designed to discharge the molten metal from the Fig. 1, according to the present disclosure. Fig. Figure 3B shows a simplified schematic view showing the open mold designed to discharge the molten metal from the Fig. 1, with the forming press inserted, according to the present disclosure. Fig. Figure 4 is a side perspective view illustrating a vehicle having a battery pack assembly with a cooling plate constructed using the method shown in Fig. 1 shown furnace system and the one in Fig. 2 to 3B, according to the present disclosure. Fig. 5 shows a perspective view showing the Fig. 4 shown battery pack assembly with the cooling plate, which is produced using the Fig. 1, according to the present disclosure. Fig. Figure 6 shows a flowchart illustrating a process for mass production of graphene composite vehicle components using the method described in Fig. 1 shown furnace system and the one in Fig. 2 to 3B, according to the present disclosure. DETAILED DESCRIPTION

[0012] The following description is merely exemplary and is not intended to limit the present disclosure, application, or uses.

[0013] With reference to Fig. Figure 1 shows a schematic view of a simplified furnace system 10 for receiving and homogenizing a graphene-containing molten metal 12 according to the principles of the present disclosure. The furnace system 10 ensures homogeneity within the matrix of the molten metal 12 when graphene or other materials are added. The furnace system 10 includes a furnace 14, a first flux injection system 16, a second flux injection system 18, and an agitator 20.

[0014] As in Fig. 1, the furnace system 10 includes at least one furnace 14. The furnace 14 is configured to apply heat to the metal, thereby creating the molten metal 12. The molten metal 12 may comprise, for example, a metal or alloy suitable for use in a vehicle (e.g., a cold plate for a vehicle's battery pack, a vehicle frame, and the like). Some examples of a molten metal or alloy may include aluminum and / or copper. In some cases, the cooling temperature of the molten metal may be 600°C or less. The furnace 14 may comprise, for example, an induction furnace, an electric arc furnace, a crucible furnace, and the like.

[0015] With reference to Fig. 1, a first flux injection system 16 is arranged to introduce a first flux 22 into an interior portion of the furnace 14 and into the molten metal 12. The first flux injection system 16 may include a degassing unit with a flux injection nozzle 24, e.g., a graphite tube or a rotating shaft, designed to inject the first flux 22 into the molten metal 12. If the molten metal 12 comprises aluminum, hydrogen gas may form in the molten aluminum and lead to undesirable holes in the finished casting. To remove the hydrogen gas, the flux injection nozzle 24 injects the first flux 22 with an inert gas, e.g., argon or nitrogen, into the molten metal 12. The inert gas combines with the hydrogen and brings the hydrogen gas to the surface, where it is released into the atmosphere. In addition, molten aluminum oxidizes rapidly.To remove the resulting oxides, the first flux 22 is blown into the molten metal 12 and onto the bottom 26 of the furnace 14. The flux adheres to the oxides and is brought to the surface 28 of the molten metal 12 by rising bubbles and then removed.

[0016] With further reference to Fig. 1, a second flux injection system 18 is arranged to introduce a graphene flux 30 into an interior portion 32 of the furnace 14 and into the molten metal 12. The second flux injection system 18 includes a second injection nozzle 34, e.g., a graphite tube or a rotating shaft. The second flux injection system 18 injects the graphene flux onto the surface 28 and / or into the molten metal 12.

[0017] The graphene flux 30 comprises at least graphene and may also contain other materials. The graphene may be present in various forms, for example, as graphene flakes, graphene particles, and / or graphene powder. Graphene flakes may be single-layer graphene flakes and / or multi-layer graphene flakes. In some cases, the graphene flakes are formed by an electrochemical exfoliation process. In one example, the average lateral diameter of the graphene flakes is between 10 nanometers (nm) and 10 micrometers (µm). The graphene flakes are sized to provide the desired mechanical, electrically conductive, and / or thermally conductive properties of the resulting graphene-aluminum composite parts.

[0018] In some cases, the graphene flux 30 comprises graphene mixed with aluminum particles (Al particles), e.g., an aluminum powder (e.g., graphene-aluminum powder), and / or copper particles (Cu particles) (e.g., graphene-copper powder). The aluminum and / or copper powder and the graphene can be formed with opposite charges, which improves both the contact between the aluminum and / or copper particles and the graphene flakes and the packing of the resulting graphene-aluminum composite powder and / or graphene-copper composite powder. Furthermore, the aluminum and / or copper can serve as a support for the graphene.

[0019] In some cases, the graphene flux 30 comprises graphene that has been plasma-treated, for example, to become more negatively charged. Plasma treatment of graphene alters the original surface properties of the graphene by using energetic and reactive radicals in the plasma to interact with the graphene surface. Plasma treatment can have various effects on the graphene, including breaking C–C bonds, removing surface atoms, and / or cleaning the graphene surface.

[0020] In some cases, the graphene flux 30 comprises graphene with a surface treatment. The use of graphene with a surface treatment improves wettability. The graphene surface may, for example, comprise a coating of copper or nickel. In the surface treatment, the coating material (e.g., copper and / or nickel) may be deposited or applied to the graphene using methods such as electrodeposition, chemical vapor deposition, and / or a solution containing the coating material (e.g., nickel sulfate hexahydrate solution).

[0021] With reference to Fig. 1, an agitator 20 is arranged to extend into the molten metal 12 in the furnace 14. As the first flux 22 and / or the graphene flux 30 are supplied to the molten metal 12, the agitator 20 rotates and mixes the molten metal 12. The mixing molten metal 12 enables the homogenization of the graphene flux 30, and the resulting mixture is transferred into a mold. In one aspect, the agitator 20 is a propeller agitator configured to create an axial flow in the molten metal 12. It should be appreciated that the agitator may also include other types of agitators or impellers, e.g., a parabolic agitator, a spiral agitator, a vane agitator, and the like.

[0022] With reference now to Fig. Figure 2 shows a schematic view of a simplified high pressure die casting (HPDC) mold 36. The HPDC mold 36 receives the homogenized mixture of molten metal and graphene flux 38 from the furnace system 10. The HPDC mold 36 includes a metal matrix 40 with a cavity 42 in the negative shape of the part to be formed and an electromagnetic stirring system 44. The mixture 38 fills the cavity 42, the HPDC mold 36 is sealed, and the mixture 38 is subjected to high pressure (e.g., over 1000 bar) until the mixture 38 solidifies.

[0023] The electromagnetic stirring system 44 is disposed within the HPDC mold 36 and utilizes a magnetic field to generate a rotating Lorentz force and fluid flow within the mixture 38. The magnetic field acts as a non-intrusive stirring device within the mixture 38 to maintain the homogenization of the graphene flux 30 until the mixture 38 solidifies. It should be noted that the electromagnetic stirring system 44 may include, for example, an electromagnetic stirrer or other systems such as an electromagnetic braking system. In some cases, the electromagnetic stirring system 44 may be coupled to the HPDC mold 36 rather than being disposed within the HPDC mold 36.

[0024] Fig. Figure 3A illustrates a schematic view of a simplified open mold 46 incorporating the electromagnetic stirring system 44. The open mold 46 may be used in addition to or alternatively to the HPDC mold 36. The open mold 46 receives the homogenized mixture of the molten metal and the graphene flux 38 from the furnace system 10. The open mold 46 includes an open die 48, with a portion 50 of the open die 48 having the negative mold of a portion of the part to be formed. The mixture 38 fills the portion 50.

[0025] With reference to Fig. 3B, after filling the open die 48 with the mixture 38, a forming press 52, which includes at least a portion of the negative mold of the part to be formed, is applied and pressed into the mixture 38 to form the part and seal the open die 46 until the mixture 38 solidifies. The electromagnetic stirring system 44 is disposed within the open die 46 and provides homogenization of the graphene flux 30 within the mixture 38. In some cases, the electromagnetic stirring system 44 may be coupled to the open die 48 rather than being disposed within the open die 48.

[0026] As in Fig. 2-3B, the HPDC mold 36 or the open mold 46 may include a vibration system 54. The vibration system 54 enables homogenization of the graphene flux 30 in the mixture 38 while providing reduced shrinkage, improved morphology, improved surface finish, and reduced hot cracking. Furthermore, the vibration system 54 may enable significant grain refinement, as well as compressive strength and hardness of the casting. In some aspects, the vibration system 54 provides frequencies from 0 to 20 Hertz (Hz) during the casting process. The vibration system 54 may be disposed as a portion of the HPDC mold 36 or the open mold 46, or may be coupled and in communication with the HPDC mold 36 or the open mold 46.

[0027] Fig. 4 shows a vehicle 56 with a battery pack assembly 58 for a vehicle having a cooling plate 60 for the vehicle's battery pack formed using the furnace system 10 and the HPDC mold 36 and / or the open mold 46. The battery pack assembly 58 provides motive power to the vehicle 56. The battery pack assembly 58 is illustrated with an exemplary vehicle 56, and the vehicle 56 is an electric vehicle or hybrid vehicle with wheels 62 powered by an electric vehicle motor (not shown).

[0028] With reference now to Fig. 5, the battery pack assembly 58, which generally includes a battery pack housing 64, the cooling plate, and a plurality of battery cells 68, is shown in a perspective view. The battery pack housing 64 generally includes a floor 70 and a plurality of sidewalls 72. The plurality of sidewalls 72 extend around a perimeter of the floor 70. The floor 70 is a generally planar member and is supported by and secured to the vehicle 56 using mechanical fasteners (not shown), such as bolts or the like, threaded through openings in the floor 70. Additionally, the battery pack housing 64 may include a top cover (not shown) coupled to the plurality of sidewalls 72. The cooling plate 60 is supported by the floor 70 of the battery pack housing 64.The cold plate 60 regulates the temperature of the battery pack enclosure 64 by dissipating heat dissipated by the batteries or other heat-generating devices and transferred to the cold plate 60. The cold plate 60 is an example of a graphene-based molded component using the HPDC mold 36 or the open mold 46 with the electromagnetic stirring system 44 disclosed herein.

[0029] Fig. 6 illustrates a method 100 for mass production of vehicle components made of graphene composite material, such as those in Fig. 4 and Fig. 5. The method 100 begins in block 102.

[0030] In block 102, the first flux 22 is injected into the molten metal 12 in the furnace 14 using the first flux injection system 16. Injecting the first flux 22 includes using a flux injection nozzle 24 to inject a gas (e.g., argon, nitrogen gas) or other material below the surface of the molten metal 12. Injecting the first flux 22 may include degassing the molten metal 12, for example, degassing hydrogen gas. Furthermore, injecting the first flux 22 may include removing oxides resulting from the oxidation of the molten metal 12, e.g., molten aluminum.

[0031] In block 104, the graphene flux 30 is injected into the molten metal using a second flux injection system 18. Injecting the graphene flux 30 includes using a second injection nozzle 34 to provide graphene below and / or on the surface 28 of the molten metal 12. Injecting the graphene flux 30 may include providing graphene in the form of powder and / or flakes in such a way that the graphene can be mixed into the molten metal 12.

[0032] In block 106, the molten metal 12 and the graphene flux 30 are stirred and homogenized in the furnace 14 using the agitator 20. Stirring the graphene flux 30 and the molten metal 12 includes using the agitator 20 to homogenize and thoroughly mix the graphene flux 30 in the mixture 38. Failure to use the agitator 20 to stir and homogenize the graphene flux 30 and the molten metal 38 may result in incomplete mixing or separation of the graphene from the molten metal 12, which is undesirable.

[0033] In block 108, the molten metal 12 is then transferred into a mold (e.g., the HPDC mold 36, the open mold 46) having an electromagnetic stirring system 44. Transferring the molten metal 12 includes pouring or otherwise flowing the molten metal mixture 38 into the mold. In some cases, transferring the molten metal 12 may include using a high-pressure system, such as a hydraulically or pneumatically operated piston or plunger device, to force the molten metal mixture 38 into the HPDC mold. In other cases, transferring the molten metal 12 may include using a pouring process and gravity to cause it to flow into the open mold 46.

[0034] In block 110, the molten metal mixture 38 is stirred using the electromagnetic stirring system 44 until the mixture 38 solidifies. The electromagnetic stirring system 44 provides and facilitates homogenization of the molten metal 12 and the graphene flux 30. Without stirring the molten metal mixture 38, the graphene added as the graphene flux 30 may clump, separate, and / or become unevenly distributed in the mixture 38, thereby reducing the benefits of the graphene. In one example, the molten metal mixture 38 is stirred using an electromagnetic stirring system 44 at a frequency between 5 and 20 hertz (Hz) and an alternating current (AC) between 50 and 300 amperes (A). The molten metal mixture 38 is continuously stirred until solidification is complete.

[0035] At block 112, the method 100 may include vibrating the molten metal 12 in the mold using ultrasonic vibrations. The ultrasonic vibration may be provided using a vibration system 54 to maintain uniform distribution and homogenization of the graphene flux 30 in the molten metal during cooling in the mold (e.g., the HPDC mold 36, the open mold 46).

[0036] In block 114, the solidified mixture 38 may be formed into a cooling component for an electric vehicle (e.g., the vehicle 56). The cooling component may include a cooling plate for a vehicle's battery pack (e.g., the cooling plate 60). In one example, the HPDC mold 36 is configured in the negative mold of the cooling component, and upon cooling of the molten metal mixture 38, the cooling component is formed. In another example, the open mold 46 and the forming press 52 are configured in the negative mold of the cooling component, and after cooling and / or solidification of the molten metal mixture 38, the forming press 52 is used to press on the cooled mixture 38 and form the cooling component therein.

[0037] In block 116, the method 100 may include releasing the cast metal from the mold after cooling and solidification, wherein the graphene flux is evenly distributed in the cooled metal. The HPDC mold 36 and / or the open mold 46 may include a cover side 74 (i.e., the forming press 52 in the case of the open mold 46) and an ejector half 76 (in Fig. 2 to 3B). The solidified mixture 38 remains in the ejector half 76 when the HPDC mold 36 or the open mold 46 is opened. The ejector half 76 includes ejector pins driven by an ejector pin plate (not shown). The ejector pins are used to release the cast metal from the HPDC mold 36 and / or the open mold 46. The method 100 is thus terminated.

[0038] The present disclosure has many advantages and benefits over prior art systems and methods for manufacturing graphene-based composite components. For example, using the furnace system 10 with an agitator 20 provides better distribution of the graphene throughout the molten metal 12. Furthermore, transferring the molten metal 12 from the furnace system 10 to the HPDC mold 36 or the open mold 46 with an electromagnetic agitator system 44 provides better distribution of graphene throughout the molten metal 12 until the molten metal 12 solidifies. This better distribution of graphene throughout the solidified casting provides a component with improved thermal conductivity and electrical conductivity.

[0039] This description is merely illustrative and is not intended to limit the disclosure, its application, or uses in any way. The broad teachings of the disclosure may be embodied in a variety of forms. Therefore, while this disclosure includes specific examples, the true scope of the disclosure should not be limited thereto, since other modifications will become apparent upon examination of the drawings, the patent specification, and the following claims.

Claims

[1] A method for mass production of vehicle components made of graphene composite material, comprising: Injecting a first flux (22) into a molten metal (12) contained in a furnace (14) using a first flux injection system (16), Injecting a graphene flux (30) into the molten metal (12) using a second flux injection system (18), Stirring and homogenizing the molten metal (12) and the graphene flux (30) in the furnace (14) using a stirrer (20), Transferring the molten metal (12) into a mold (36, 46) having an electromagnetic stirring system (44), and Stirring the molten metal (12) with the electromagnetic stirring system (44) until the molten metal (12) solidifies, wherein the electromagnetic stirring system (44) maintains the homogenization of the molten metal (12) and the graphene flux (30). [2] The method of claim 1, wherein degassing and injecting the first flux (22) into the molten metal (12) comprises injecting the first flux (22) into molten copper and / or molten aluminum. [3] The method of claim 1, wherein degassing and blowing the first flux (22) comprises blowing nitrogen gas and / or argon. [4] The method of claim 1, wherein injecting the graphene flux (30) into the molten metal (12) comprises injecting graphene having a surface treatment. [5] The method of claim 4, wherein the surface treatment comprises nickel and / or copper deposited on the graphene flux (30). [6] The method of claim 1, wherein injecting the graphene flux (30) into the molten metal (12) comprises injecting graphene that has been premixed with graphene-aluminum powder and / or graphene-copper powder. [7] The method of claim 1, wherein stirring and homogenizing the molten metal (12) and the graphene flux (30) comprises using a propeller stirrer (20). [8] The method of claim 1, wherein transferring the molten metal (12) into the mold (36) having the electromagnetic stirring system (44) comprises injecting the molten metal (12) into a die casting mold (36). [9] The method of claim 1, wherein transferring the molten metal (12) into the mold (46) having the electromagnetic stirring system (44) comprises pouring the molten metal (12) into an open die (48).

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