Graphene coating liquid-based cooling plate and preparation method thereof

Abstract

The application relates to the technical field of liquid cooling plates, and particularly discloses a graphene-coated liquid cooling plate, which comprises an upper substrate, a lower substrate and a graphene coating, the upper substrate is provided with a groove, a flow channel for circulating cooling liquid is formed between the upper substrate and the lower substrate through the groove, the flow channel is connected with an inlet and an outlet respectively, the graphene coating is arranged on one side of the lower substrate away from the upper substrate, the graphene coating is provided with concave unit microstructures arranged in an array, the upper substrate and the lower substrate are connected through rolling, and the flow channel is prepared through blow molding. The graphene-coated liquid cooling plate utilizes the excellent heat conductivity of the graphene coating to conduct heat to the cooling liquid in the flow channel of the liquid cooling plate, the concave unit microstructures on the surface of the graphene coating can increase the heat exchange area to sufficiently dissipate and transfer heat, the heat exchange efficiency is improved, and the heat dissipation effect of the liquid cooling plate is improved. The rolling connection-blow molding is adopted to improve the sealing reliability and overall formability of the liquid cooling plate.

Description

Technical Field

[0001] This invention belongs to the field of liquid cooling plate technology, and specifically relates to a graphene-coated liquid cooling plate and its preparation method. Background Technology

[0002] The power battery is the energy source for new energy electric vehicles, and its efficiency limits the driving range and speed of these vehicles. Power batteries operate with high current and generate a lot of heat. Furthermore, the battery is in a relatively enclosed environment, making heat dissipation difficult and easily leading to overheating. Power batteries are highly sensitive to temperature; excessively high temperatures can cause poor consistency in battery pack modules, shorten their lifespan, and also reduce the lifespan of the motor and electronic control system. In severe cases, it can even trigger thermal runaway, leading to battery explosion. The performance, safety, and stability of the battery will be a crucial factor influencing the future development of new energy electric vehicles. Liquid cooling plates can effectively solve the problems of heat dissipation difficulties and excessively high temperatures in power batteries. Liquid cooling plates work by circulating coolant through their channels, quickly removing a large amount of heat and achieving rapid cooling of the battery pack.

[0003] Existing liquid cooling plates suffer from the following drawbacks: Tube-type liquid cooling plates are bulky and occupy a large amount of space; the shape of the circular tube itself imposes significant limitations on battery pack design; the tubular heat sink is structurally constrained, resulting in a relatively small contact area between the tube and the heat exchange surface, thus reducing heat exchange efficiency and making it unsuitable for the complex structural features of battery boxes; Profile-type liquid cooling plates have excessively thick walls, making them heavy and failing to achieve weight reduction in battery systems, while also incurring high costs; The process of stamping the upper and lower plates and then brazing them is difficult to manufacture, and in cases of complex liquid cooling plate shapes, it is hard to ensure the overall sealing of the upper and lower liquid cooling plates, resulting in low processing efficiency, a high defect rate, significant welding pollution, and poor heat dissipation performance. Therefore, there is an urgent need to develop new, safe, environmentally friendly, and high-performance liquid cooling plates. Summary of the Invention

[0004] The purpose of this invention is to provide a graphene-coated liquid cooling plate and its preparation method, overcoming the shortcomings and defects of the prior art.

[0005] To achieve the above objectives, this invention provides a graphene-coated liquid cooling plate, comprising: an upper substrate, a lower substrate, and a graphene coating. The upper substrate has grooves, forming a flow channel for coolant circulation between the upper and lower substrates. The flow channel is connected to an inlet and an outlet. The graphene coating is located on the side of the lower substrate away from the upper substrate and features an array of concave microstructures. The upper and lower substrates are joined together by rolling, and the flow channel is formed by blow molding. The graphene coating possesses excellent thermal conductivity, facilitating heat transfer to the coolant. The array of concave microstructures on the graphene coating surface increases the heat exchange area for sufficient heat dissipation and transfer, improving heat exchange efficiency and enhancing the heat dissipation effect of the liquid cooling plate. The use of rolling and blow molding results in higher sealing reliability and better overall formability of the liquid cooling plate.

[0006] Preferably, in the above-mentioned graphene-coated liquid cooling plate, the concave unit microstructure is cylindrical in shape.

[0007] Preferably, in the above-mentioned graphene-coated liquid cooling plate, the diameter of the concave unit microstructure is 100~300μm, the depth is 20~40μm, and the spacing between the concave unit microstructures is 100~300μm.

[0008] Preferably, in the above-mentioned graphene-coated liquid cooling plate, the lower substrate is a graphene-reinforced aluminum substrate, and the upper substrate is an aluminum plate. Using a graphene-reinforced aluminum substrate for the lower substrate provides good strength and thermal conductivity, while using an aluminum plate for the upper substrate facilitates blow molding.

[0009] A method for preparing the above-mentioned graphene-coated liquid cooling plate includes the following steps:

[0010] (1) Preparation of graphene-reinforced aluminum substrate;

[0011] (2) Roughen one side of the graphene-reinforced aluminum substrate, block the non-flow channel area, apply graphene oil-based coating to the rough surface of the graphene-reinforced aluminum substrate, and dry to form a graphene flow channel circuit diagram.

[0012] (3) The side of the graphene-reinforced aluminum substrate with the graphene flow channel diagram obtained in step (2) is covered with an aluminum plate and then subjected to hot rolling composite and annealing treatment.

[0013] (4) The flow channel is formed by blowing process;

[0014] (5) Roughen the side of the graphene-reinforced aluminum substrate away from the upper substrate and coat it with a graphene coating.

[0015] (6) A concave unit microstructure arranged in an array was prepared on a graphene coating by laser etching.

[0016] Preferably, in the above-mentioned method for preparing a graphene-coated liquid cooling plate, in step (1), the preparation process of the graphene-reinforced aluminum substrate is as follows: a tin film is formed on the surface of graphene aerogel by vacuum evaporation; the graphene aerogel with the tin film on its surface is stirred and crushed to obtain graphene powder with the tin film on its surface; aluminum ingots are melted into aluminum liquid, and the graphene powder with the tin film is added and mixed, with the weight ratio of graphene to aluminum ingot being 0.002~0.005:1; the mixture is poured into a mold for cooling, rolled, and annealed to obtain the graphene-reinforced aluminum substrate. Adding graphene can improve the strength and thermal conductivity of aluminum plates. However, graphene and aluminum have different densities and surface properties, making it difficult for graphene to be evenly dispersed in aluminum substrates. Graphene powder with a tin film on its surface can improve the wettability between the graphene powder and the aluminum substrate, enhance the uniformity of graphene dispersion in the aluminum substrate, and the tin film on the surface can also effectively prevent carbon from reacting with aluminum at high temperatures to form a brittle phase, thereby improving the strength of the aluminum plate.

[0017] Preferably, in the above-mentioned method for preparing a graphene-coated liquid cooling plate, the graphene oil-based coating is obtained by mixing graphene powder and polydimethylsiloxane at a mass ratio of 1:8~15, and then diluting it 3~8 times with an organic solvent.

[0018] Preferably, in the above-mentioned method for preparing a graphene-coated liquid cooling plate, in step (3), the hot rolling temperature is 400~450℃, and the annealing treatment is: hot pressing at 400℃~450℃ for 1h~3h.

[0019] Preferably, in the above-mentioned method for preparing a graphene-coated liquid cooling plate, step (5) specifically includes: dispersing graphene oxide in water at a ratio of 1-15 mg: 1 ml, then adding 30-50% (by weight of graphene oxide) of γ-aminopropyltriethoxysilane, and ultrasonically dispersing for 1-3 h to obtain a modified graphene oxide dispersion; coating the modified graphene oxide dispersion onto the roughened surface of a graphene-reinforced aluminum substrate, and then heat-treating it at 400-500°C for 1-2 h in a hydrogen and argon atmosphere to obtain a graphene coating. Modifying graphene oxide with γ-aminopropyltriethoxysilane and then coating it onto the substrate enhances the bonding force between the graphene coating and the substrate.

[0020] Preferably, in the above-described method for preparing a graphene-coated liquid cooling plate, the thickness of the graphene coating is 30~50μm.

[0021] Compared with existing technologies, the present invention has the following advantages:

[0022] 1. The graphene-coated liquid cooling plate of this invention utilizes the excellent thermal conductivity of the graphene coating to conduct heat to the coolant in the flow channels of the liquid cooling plate. An array of concave microstructures arranged on the surface of the graphene coating increases the heat exchange area for sufficient heat dissipation and transfer, improving heat exchange efficiency and enhancing the heat dissipation effect of the liquid cooling plate. The upper and lower substrates are connected by rolling, and the flow channels are formed by blow molding, resulting in higher sealing reliability and better overall formability of the liquid cooling plate.

[0023] 2. In the preparation method of the graphene-coated liquid cooling plate of the present invention, graphene powder with a tin film on its surface is mixed with aluminum liquid to prepare a graphene-reinforced aluminum substrate. This improves the wettability between the graphene powder and the aluminum matrix, enhances the uniform dispersion of graphene in the aluminum matrix, and the surface tin film effectively prevents carbon from reacting with aluminum at high temperatures to form a brittle phase, thereby improving the strength and thermal conductivity of the aluminum plate. A graphene oil-based coating is applied to the rough surface of the graphene-reinforced aluminum substrate to form a graphene flow channel diagram. Due to the anti-bonding effect of graphene, the flow passages are not connected during the rolling connection of the upper and lower substrates. Flow channels for the coolant can be obtained through blow molding. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the liquid cooling plate structure in Embodiment 1 of the present invention.

[0025] Figure 2 This is a partially enlarged schematic diagram of the graphene coating structure of the liquid cooling plate in Embodiment 1 of the present invention.

[0026] Main illustrations:

[0027] 1-Upper substrate, 2-Lower substrate, 3-Graphene coating, 4-Flow channel, 5-Inlet, 6-Outlet, 7-Concave unit microstructure. Detailed Implementation

[0028] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0029] Example 1

[0030] like Figure 1 and Figure 2As shown, a graphene-coated liquid cooling plate includes an upper substrate 1, a lower substrate 2 connected to the upper substrate 1 by rolling, and a graphene coating 3 disposed on the side of the lower substrate 2 away from the upper substrate 1. The upper substrate 1 has grooves, forming a flow channel 4 for coolant circulation between the upper substrate 1 and the lower substrate 2. The flow channel 4 is connected to an inlet 5 and an outlet 6, respectively, and is formed by blow molding. The graphene coating 3 has an array of concave microstructure units 7. The concave microstructure units are cylindrical, with a diameter of 200 μm and a depth of 20 μm, and the spacing L between the concave microstructure units is 200 μm. The upper substrate 1 is an aluminum plate, and the lower substrate 2 is a graphene-reinforced aluminum substrate.

[0031] The preparation method of the graphene-coated liquid cooling plate in this embodiment includes the following steps:

[0032] (1) Preparation of graphene-reinforced aluminum substrate:

[0033] A tin film was formed on the surface of graphene aerogel using vacuum evaporation. The graphene aerogel was placed in a vacuum coating apparatus, and the vacuum chamber was evacuated to a vacuum level of 0.1 Pa. The sample was then subjected to ion bombardment at a voltage of 200 V for 30 min. Tin plating was then performed, with the vacuum evaporation working pressure at 10 kPa. -4 A graphene aerogel with an aluminum film on its surface was obtained by evaporation at a power of 300W and a deposition time of 10min. The graphene aerogel with a tin film on its surface was then pulverized by sealed magnetic stirring at a speed of 500rpm / min for 15min to obtain graphene powder with a tin film on its surface. Aluminum ingots were melted in a furnace at 650℃ to form molten aluminum, and the graphene powder with a tin film was added and stirred at a weight ratio of 0.0035:1 (graphene to aluminum ingot). The mixture was poured into a mold, cooled at room temperature, and pressed to obtain a graphene-reinforced aluminum substrate.

[0034] (2) Roughen one side of the graphene-reinforced aluminum substrate to block the non-flow channel area. Apply graphene oil-based coating to the rough surface of the graphene-reinforced aluminum substrate. The graphene oil-based coating is obtained by mixing graphene powder and polydimethylsiloxane at a mass ratio of 1:12 and then diluting it with toluene 5 times. Dry it in a vacuum at 100°C to form the graphene flow channel circuit diagram.

[0035] (3) The graphene-reinforced aluminum substrate obtained in step (2) is covered with a pure aluminum plate on one side with the graphene flow channel circuit diagram, aligned and riveted, heated in a 400°C furnace, and then rolled in a hot rolling mill. Then it is hot-pressed at 450°C for 1 hour to obtain a composite aluminum plate.

[0036] (4) Drill process holes to the graphene layer at the graphene circuit position of the composite aluminum plate, and introduce air through the process holes. The aluminum plate on the graphene flow channel expands to form a flow channel for the flow of coolant.

[0037] (5) Roughening is performed on the side of the graphene-reinforced aluminum substrate away from the upper substrate, and a graphene coating is applied. The specific process includes: dispersing graphene oxide in water at a ratio of 10 mg to 1 ml, then adding 30% of the weight of graphene oxide in r-aminopropyltriethoxysilane, and ultrasonically dispersing for 2 hours to obtain a modified graphene oxide dispersion; coating the modified graphene oxide dispersion onto the roughened surface of the graphene-reinforced aluminum substrate, and then applying it under a hydrogen and argon atmosphere ( V (H2): V A graphene coating with a thickness of 30 μm was obtained by heat treatment at 450 °C for 1 h in (Ar)=30:70.

[0038] (6) A concave unit microstructure arranged in an array was prepared on the graphene coating by laser etching. During laser processing, the control power was 5W, the frequency was 20000Hz, the pulse was 300ns, and the scanning speed was 300mm / s.

[0039] Example 2

[0040] A graphene-coated liquid cooling plate includes an upper substrate, a lower substrate connected to the upper substrate by rolling, and a graphene coating on the side of the lower substrate away from the upper substrate. The upper substrate has grooves, forming flow channels for coolant flow between the upper and lower substrates. These flow channels are connected to an inlet and an outlet, respectively, and are formed by blow molding. The graphene coating has an array of concave microstructure units. Each concave microstructure unit is cylindrical, with a diameter of 200 μm and a depth of 20 μm, and the spacing L between the concave microstructure units is 100 μm. The upper substrate is an aluminum plate, and the lower substrate is a graphene-reinforced aluminum substrate.

[0041] The preparation method of the graphene-coated liquid cooling plate in this embodiment includes the following steps:

[0042] (1) Preparation of graphene-reinforced aluminum substrate:

[0043] A tin film was formed on the surface of graphene aerogel using vacuum evaporation. The graphene aerogel was placed in a vacuum coating apparatus, and the vacuum chamber was evacuated to a vacuum level of 0.1 Pa. The sample was then subjected to ion bombardment at a voltage of 200 V for 30 min. Tin plating was then performed, with the vacuum evaporation working pressure at 10 kPa. -4A graphene aerogel with an aluminum film on its surface was obtained by evaporation at a power of 300W and a deposition time of 10min. The graphene aerogel with a tin film on its surface was then pulverized by sealed magnetic stirring at a speed of 500rpm / min for 15min to obtain graphene powder with a tin film on its surface. Aluminum ingots were melted in a furnace at 650℃ to form molten aluminum, and the graphene powder with a tin film was added and stirred at a weight ratio of 0.002:1 (graphene to aluminum ingot). The mixture was poured into a mold, cooled at room temperature, and pressed to obtain a graphene-reinforced aluminum substrate.

[0044] (2) Roughen one side of the graphene-reinforced aluminum substrate to block the non-flow channel area. Apply graphene oil-based coating to the rough surface of the graphene-reinforced aluminum substrate. The graphene oil-based coating is obtained by mixing graphene powder and polydimethylsiloxane at a mass ratio of 1:12 and then diluting it with toluene 5 times. Dry it in a vacuum at 100°C to form the graphene flow channel circuit diagram.

[0045] (3) The graphene-reinforced aluminum substrate obtained in step (2) is covered with a pure aluminum plate on one side with the graphene flow channel circuit diagram, aligned and riveted, heated in a 400°C furnace, and then rolled in a hot rolling mill. Then it is hot-pressed at 450°C for 1 hour to obtain a composite aluminum plate.

[0046] (4) Drill process holes to the graphene layer at the graphene circuit position of the composite aluminum plate, and introduce air through the process holes. The aluminum plate on the graphene flow channel expands to form a flow channel for the flow of coolant.

[0047] (5) Roughening is performed on the side of the graphene-reinforced aluminum substrate away from the upper substrate, and a graphene coating is applied. The specific process includes: dispersing graphene oxide in water at a ratio of 10 mg to 1 ml, then adding 30% of the weight of graphene oxide in r-aminopropyltriethoxysilane, and ultrasonically dispersing for 2 hours to obtain a modified graphene oxide dispersion; coating the modified graphene oxide dispersion onto the roughened surface of the graphene-reinforced aluminum substrate, and then applying it under a hydrogen and argon atmosphere ( V (H2): V A graphene coating with a thickness of 30 μm was obtained by heat treatment at 450 °C for 1 h in (Ar)=30:70.

[0048] (6) A concave unit microstructure arranged in an array was prepared on the graphene coating by laser etching. During laser processing, the control power was 5W, the frequency was 20000Hz, the pulse was 300ns, and the scanning speed was 300mm / s.

[0049] Comparative Example 1

[0050] This comparative example is the same as Example 1, except that the graphene coating 3 in this comparative example does not have an array of concave unit microstructures. The liquid cooling plates of Example 1 and Comparative Example 1 dissipate heat from the battery; the liquid cooling plate of Example 1 has high heat dissipation efficiency and good heat dissipation effect.

[0051] Comparative Example 2

[0052] This comparative example is the same as Example 1, except that step (1) in the preparation method is as follows: an aluminum film is formed on the surface of graphene aerogel by vacuum evaporation. The graphene aerogel is placed in a vacuum coating equipment, and the vacuum chamber is evacuated to a vacuum degree of 0.1 Pa. The sample is then bombarded with ions at a voltage of 200 V for a time of 30 min. Then, aluminum is deposited, and the working pressure of the vacuum evaporation is 5 × 10⁻⁶. -3 At a pressure of 500W and a deposition time of 5 minutes, graphene aerogel with an aluminum film on its surface was obtained. The graphene aerogel with the aluminum film on its surface was then crushed by sealed magnetic stirring at a speed of 500 rpm / min for 15 minutes to obtain graphene powder with an aluminum film on its surface. Aluminum ingots were melted in a furnace at 650℃ to form molten aluminum, and the graphene powder with the aluminum film was added and stirred at a weight ratio of 0.0035:1 (graphene to aluminum ingot). The mixture was poured into a mold, cooled at room temperature, and pressed to obtain a graphene-reinforced aluminum substrate.

[0053] The thermal conductivity of the graphene-reinforced aluminum substrates and pure aluminum plates prepared in Examples 1-2 and Comparative Example 2 was measured using a laser thermal conductivity meter. Tensile strength tests were conducted on the graphene-reinforced aluminum substrates and pure aluminum plates prepared in Examples 1-2 and Comparative Example 2 using a universal testing machine. Plate-shaped specimens were used for the tests, which were performed according to HB5143-96, the method for room temperature tensile testing of metals. The results are shown in Table 1.

[0054] As shown in Table 1, the thermal conductivity and tensile strength of the example group are higher than those of the comparative example and the pure aluminum plate, indicating that the thermal conductivity and mechanical properties of the graphene-reinforced aluminum substrate prepared by the present invention are improved, which is beneficial to improving the heat dissipation performance, heat exchange efficiency and load-bearing capacity of the liquid cooling plate.

[0055] Table 1. Thermal conductivity and tensile strength of graphene-reinforced aluminum substrate and pure aluminum plate

[0056] Group Tensile strength (MPa) Thermal conductivity / W / (m * K) Example 1 190.4 247.8 Example 2 181.2 236.1 Comparative Example 2 183.5 241.7 pure aluminum plate 113.8 211.5

[0057] The foregoing description of specific exemplary embodiments of the invention is for illustrative and explanatory purposes. These descriptions are not intended to limit the invention to the precise forms disclosed, and it will be apparent that many changes and variations can be made in accordance with the foregoing teachings. The exemplary embodiments were chosen and described in order to explain the specific principles of the invention and its practical application, thereby enabling those skilled in the art to implement and utilize various different exemplary embodiments of the invention, as well as various different choices and variations. The scope of the invention is intended to be defined by the claims and their equivalents.

Claims

1. A method for preparing a graphene-coated liquid cooling plate, characterized in that, The liquid cooling plate includes: an upper substrate, a lower substrate, and a graphene coating. The lower substrate is a graphene-reinforced aluminum substrate, and the upper substrate is an aluminum plate. The upper substrate has grooves, forming flow channels for coolant flow between the upper and lower substrates. These flow channels are connected to an inlet and an outlet. The graphene coating is located on the side of the lower substrate away from the upper substrate, and the graphene coating has an array of concave microstructure units. The upper and lower substrates are connected by rolling, and the flow channels are formed by blow molding. The preparation method includes the following steps: (1) Preparation of graphene-reinforced aluminum substrate: A tin film is formed on the surface of graphene aerogel by vacuum evaporation; the graphene aerogel with the tin film on the surface is stirred and crushed to obtain graphene powder with the tin film on the surface; aluminum ingot is melted into aluminum liquid, and the graphene powder with the tin film is added and mixed according to the weight ratio of graphene to aluminum ingot of 0.002~0.005:1; the mixture is poured into a mold and cooled to obtain graphene-reinforced aluminum substrate. (2) Roughen one side of the graphene-reinforced aluminum substrate, block the non-flow channel area, apply graphene oil-based coating to the rough surface of the graphene-reinforced aluminum substrate, and dry to form a graphene flow channel circuit diagram. (3) The side of the graphene-reinforced aluminum substrate with the graphene flow channel circuit diagram obtained in step (2) is covered with an aluminum plate, and hot rolling composite and annealing are performed. The hot rolling temperature is 400~450℃, and the annealing treatment is: hot pressing at 400℃~450℃ for 1h~3h. (4) The flow channel is formed by blowing process; (5) Roughen the side of the graphene-reinforced aluminum substrate away from the upper substrate and coat it with a graphene coating. (6) A concave unit microstructure arranged in an array was prepared on a graphene coating by laser etching.

2. The method for preparing a graphene-coated liquid cooling plate according to claim 1, characterized in that, The concave unit microstructure is cylindrical in shape.

3. The method for preparing a graphene-coated liquid cooling plate according to claim 1, characterized in that, The concave unit microstructure has a diameter of 100~300μm, a depth of 20~40μm, and a spacing of 100~300μm between the concave unit microstructures.

4. The method for preparing a graphene-coated liquid cooling plate according to claim 1, characterized in that, The graphene oil-based coating is obtained by mixing graphene powder and polydimethylsiloxane at a mass ratio of 1:8~15, and then diluting it 3~8 times with an organic solvent.

5. The method for preparing a graphene-coated liquid cooling plate according to claim 1, characterized in that, The specific process of step (5) includes: dispersing graphene oxide in water at a ratio of 1~15 mg: 1 ml, then adding 30~50% of the weight of graphene oxide in γ-aminopropyltriethoxysilane, ultrasonically dispersing for 1~3 h to obtain a modified graphene oxide dispersion; coating the modified graphene oxide dispersion onto the roughened surface of a graphene-reinforced aluminum substrate, and then heat-treating it at 400~500℃ for 1~2 h in a hydrogen and argon atmosphere to obtain a graphene coating.

Images