Graphene foam copper composite heat sink and preparation method thereof

Abstract

The application discloses a graphene foam copper composite radiator and a preparation method thereof, and belongs to the technical field of radiators.The composite radiator adopts foam copper or foam aluminum as a porous matrix, graphene nanoceramic slurry is vacuum-filled in the internal pores of the porous matrix, and a dense and gap-free graphene nanoceramic slurry solidification layer is formed; by limiting the porosity of the porous matrix, the slurry ratio and the preparation process parameters, the overall density of the composite radiator is controlled to be 0.7-3.8 g / cm3, and the overall thermal conductivity is greater than or equal to 1200 W / m*K; the application solves the problems that the traditional single metal radiator cannot simultaneously consider light weight and high thermal conductivity, the traditional composite radiator has interface gaps, large thermal resistance, an easy-to-fall coating, low yield and the like, and the pure foam metal radiator has insufficient heat dissipation efficiency; the product has various structures, high structural stability, excellent corrosion resistance and oxidation resistance, and a stable and controllable preparation process.

Description

Technical Field

[0001] This invention relates to the field of radiator manufacturing technology, specifically to a graphene foam copper composite material radiator and its manufacturing method. Background Technology

[0002] With the rapid iteration of new energy equipment, high-precision electronic instruments, and high-power heat sink manufacturing devices, the operating power of equipment continues to increase, and the heat generation per unit volume increases significantly, which puts forward higher requirements for the thermal conductivity, lightweight, structural stability and service life of heat sinks.

[0003] Currently, most mainstream radiators on the market are made of a single metal material such as pure copper, pure aluminum, or aluminum alloy. Pure copper radiators have good thermal conductivity, but their high density and weight make them unsuitable for the assembly requirements of lightweight equipment. Aluminum and aluminum alloy radiators are lighter, but their thermal conductivity is limited, resulting in insufficient heat dissipation efficiency in high-power scenarios. Furthermore, the metal surface is prone to oxidation and corrosion, leading to significant performance degradation over long-term use. Meanwhile, traditional composite radiators often employ a simple surface coating process, which can easily result in interfacial gaps and bubbles between the coating and the metal substrate. This leads to high interfacial thermal resistance and a high risk of coating peeling and incomplete filling, resulting in unstable overall thermal conductivity and low yield rates.

[0004] Foam metal has the advantages of being porous, lightweight, having a large specific surface area, and being highly malleable, making it a high-quality substrate material for heat sinks. However, the internal structure of individual foam metal pores is hollow, and the thermal conductivity of air is extremely low, which limits the overall heat dissipation efficiency of foam metal heat sinks and makes them unable to meet the rapid heat dissipation requirements of high-power equipment. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a graphene foam copper composite material heat sink and its preparation method.

[0006] The technical problem to be solved by this invention is achieved through the following technical solution: This invention provides a graphene-copper foam composite heat sink, using copper foam or aluminum foam as a porous matrix, wherein the pores of the porous matrix are filled with a cured graphene nano-ceramic slurry layer; the porosity of the porous matrix is ​​60%–90%, the overall density of the composite heat sink is 0.7–3.8 g / cm³, and the overall thermal conductivity of the composite heat sink is ≥1200 W / (m³). K).

[0007] Furthermore, the porous matrix is ​​copper foam, the porosity of the copper foam is 75% to 90%, and the pore size of the copper foam is 0.5 to 5 mm.

[0008] Furthermore, the porous matrix is ​​aluminum foam, the porosity of the aluminum foam is 60% to 85%, and the pore size of the aluminum foam is 1 to 8 mm.

[0009] Furthermore, the graphene nano-ceramic slurry curing layer is continuously and densely filled in the pores of the porous matrix, and there are no pores or interface gaps between the graphene nano-ceramic slurry curing layer and the porous matrix.

[0010] Furthermore, the overall structure of the composite radiator can be any one of plate-shaped, column-shaped, fin-shaped, or honeycomb-shaped.

[0011] Furthermore, the graphene nano-ceramic slurry curing layer is made of graphene powder, nano-ceramic powder, organic binder, and deionized water; wherein the content of graphene powder is 3% to 10 wt%, and the content of nano-ceramic powder is 15% to 25 wt%.

[0012] In another aspect, the present invention provides a method for preparing the above-mentioned graphene foam copper composite heat sink, characterized by comprising the following steps: Step 1: Select a porous substrate of copper foam or aluminum foam with matching specifications, process it to the preset size and structural specifications through cutting and shaping processes, and remove burrs, oxide layer and impurities in the pores of the porous substrate surface. Step 2: Place the processed porous substrate flat into the customized molding mold, complete the positioning and fixation, and seal the mold cavity; Step 3: Evacuate the mold cavity to 10°C. - ¹Pa vacuum degree, after holding pressure for 3 to 10 minutes, uniformly inject graphene nano-ceramic slurry into the mold to completely wet and fill the pores of the porous matrix. Step 4: Place the porous matrix after injection molding, along with the molding die, into a drying device and dry and cure at a constant temperature to obtain a preliminary composite matrix; Step 5: Perform surface finishing and protective treatment on the dried and cured composite substrate to remove residual slurry and defects, and finally obtain the composite heat sink; Step 6: Test the thermal conductivity, density, and appearance accuracy of the processed composite heat sink. After passing the tests, remove dust and package it.

[0013] Furthermore, in step 4, the drying and curing temperature is 50-150℃, the drying and curing time is 6-13h, and the drying process adopts a segmented heating mode with a heating rate of 2-5℃ / min.

[0014] Furthermore, the surface treatment in step 5 is at least one of mechanical grinding, mirror polishing, and spraying an anti-oxidation and anti-corrosion coating; the thickness of the anti-oxidation and anti-corrosion coating is 5 to 20 μm.

[0015] Furthermore, after the slurry injection in step 3 is completed, maintain for 10 minutes. - Allow the slurry to stand in a vacuum environment for 5–15 minutes to ensure that the slurry fully penetrates the micropores of the matrix and eliminates air bubbles.

[0016] As can be seen from the above, the graphene foam copper composite heat sink and its preparation method provided in this application use foam copper or foam aluminum as a porous matrix and fill the pores with graphene nano-ceramic slurry. After drying and curing, the porous matrix and graphene nano-ceramic slurry are composited. At the same time, a continuous and dense thermally conductive layer structure is ensured, and interfacial gaps and bubbles are avoided, thereby achieving high thermal conductivity and low density. It has the advantages of efficient heat dissipation while significantly reducing weight.

[0017] Compared with the prior art, the present invention has the following significant advantages: 1. This invention employs a vacuum grouting and curing process, which enables the graphene nano-ceramic slurry to continuously and densely fill the porous interior of the foamed metal. There are no interfacial gaps or bubble defects between the matrix and the cured layer, significantly reducing interfacial thermal resistance. The overall thermal conductivity of the product is ≥1200W / m·K, far exceeding that of traditional copper-aluminum heat sinks, and can meet the high heat flux density and rapid heat dissipation requirements of high-power equipment.

[0018] 2. This invention can balance structural strength and lightweight performance by adjusting the porosity of foamed copper and foamed aluminum. The overall density of the product is only 0.7 to 3.8 g / cm³, which effectively solves the defects of traditional pure copper heat sinks, such as large weight and high assembly load, and is suitable for assembly scenarios of portable and lightweight electronic devices.

[0019] 3. In the graphene nano-ceramic slurry curing layer used in this invention, the graphene has ultra-high thermal conductivity, and the nano-ceramic powder has the advantages of high temperature resistance, oxidation resistance, and corrosion resistance. Combined with the surface protective coating, it can effectively avoid the problems of oxidation corrosion and performance degradation of the heat sink during long-term high-temperature operation, and greatly extend the service life of the equipment. Attached Figure Description

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0021] Figure 1 This is a schematic flowchart of a method for preparing a graphene foam copper composite heat sink according to the present invention. Figure 2 This is a partially enlarged schematic diagram of the foamed copper in a graphene foamed copper composite heat sink according to the present invention. Figure 3 This is a partially enlarged schematic diagram of a graphene foam copper composite material heat sink according to the present invention. Detailed Implementation

[0022] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments. The components of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0023] It should be noted that similar reference numerals and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures. Furthermore, in the description of this application, terms such as "first," "second," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0024] Example 1: like Figure 2 ~as Figure 3 As shown, this invention provides a graphene-copper foam composite heat sink, wherein the composite heat sink uses copper foam or aluminum foam as a porous matrix, and the pores of the porous matrix are filled with a cured graphene nano-ceramic slurry layer; the porosity of the porous matrix is ​​60% to 90%, the overall density of the composite heat sink is 0.7 to 3.8 g / cm³, and the overall thermal conductivity of the composite heat sink is ≥1200 W / (m³). K).

[0025] Furthermore, the porosity range of the porous matrix was optimized to balance the requirements of lightweight design and heat dissipation surface area; a graphene nano-ceramic slurry solidification layer was filled inside the pores, eliminating hollow structures and reducing interfacial thermal resistance; and the overall density and thermal conductivity of the composite heat sink were limited to ensure both lightweight characteristics and efficient heat dissipation. As a result, the heat conduction path efficiency of the heat sink was improved, the weight was controlled, the interfacial thermal resistance was reduced, and the problem of insufficient heat dissipation caused by hollow pores was solved.

[0026] The main technical features of the graphene foam copper composite material heat sink proposed in this application are as follows: First, this composite radiator uses either copper foam or aluminum foam as a porous matrix, and the choice of porous matrix is ​​crucial to the overall performance of the radiator. For example, copper foam can be prepared using electrodeposition or powder metallurgy, and different pore sizes and porosities can be obtained by adjusting process parameters. Alternatively, aluminum foam can be prepared using melt foaming or sintering methods to meet specific structural and performance requirements. These porous matrices, due to their inherent lightweight properties and large specific surface area, provide the radiator with a good initial structure and heat transfer interface.

[0027] Secondly, the pores of the porous matrix are filled with a cured graphene nano-ceramic slurry layer. Various methods can be used to achieve this filling process. For example, the prepared graphene nano-ceramic slurry can be directly poured into the porous matrix, allowing it to naturally penetrate and fill the pores. Alternatively, a simple impregnation coating method can be used to allow the slurry to adhere to and enter the pores of the porous matrix. After the slurry filling is complete, it is cured by heating or natural drying, thereby forming a continuous cured layer inside the pores of the porous matrix.

[0028] Furthermore, the porosity of the porous matrix is ​​set to 60%–90%. Porosity control can be achieved by adjusting the preparation process of the porous matrix. For example, in the preparation of foamed metals, matrices with different porosities can be obtained by changing parameters such as the amount of foaming agent added or the sintering temperature. This porosity range is designed to provide sufficient space for filling with a highly thermally conductive slurry while ensuring the integrity of the matrix structure, thus achieving a balance between lightweighting and thermal conductivity.

[0029] Furthermore, the overall density of the composite heat sink is controlled within the range of 0.7–3.8 g / cm³. This overall density is the result of the combined effects of the selection of the porous matrix material, its porosity, and the density of the filler material. For example, by selecting low-density aluminum foam as the matrix, combined with appropriate porosity and filler content, a lower overall density can be obtained. Conversely, if relatively high-density copper foam is selected, higher porosity and precise filler content control are required to meet the density requirements.

[0030] Finally, the overall thermal conductivity of the composite heat sink was designed to be ≥1200W / (m²). This high thermal conductivity is primarily achieved through the synergistic effect of the porous matrix and the graphene nanoceramic slurry solidification layer. For example, heat is first conducted through the metal framework of the porous matrix, while the graphene nanoceramic solidification layer filling the pores provides an additional, highly efficient heat conduction path. By optimizing the material selection and structural design of the matrix and filling layer, heat can be quickly and effectively conducted from one end of the heat sink to the other, thus achieving efficient heat dissipation.

[0031] The following example will provide a more detailed explanation of the above technical solution: Suppose that at location A, user A needs to design a new type of heatsink for a high-power server. This server generates a large amount of heat during operation, and traditional heatsinks are unsuitable due to insufficient thermal conductivity, excessive weight, or susceptibility to corrosion. Specifically, user A faces the following problems: existing pure copper heatsinks, while having good thermal conductivity, are too heavy; pure aluminum heatsinks are lightweight but lack sufficient thermal conductivity and are prone to oxidation over long-term use; while simple composite-coated heatsinks suffer from high interfacial thermal resistance and easy coating peeling, resulting in unstable heat dissipation performance.

[0032] To address these issues, this application proposes a graphene-copper foam composite heat sink that effectively solves the aforementioned problems. Specifically, firstly, a copper foam is selected as the porous matrix. This copper foam is lightweight and has a high specific surface area, with its porosity controlled at around 75% to ensure sufficient structural support while reserving ample space for subsequent filling materials.

[0033] Subsequently, the prepared graphene nano-ceramic slurry was injected into the pores of the porous copper foam matrix. This slurry, composed of highly thermally conductive graphene powder and nano-ceramic powder, exhibits excellent flowability and filling properties. By precisely controlling the injection speed and environmental conditions, the slurry was able to fully wet and fill all the pores of the copper foam matrix, avoiding the formation of air bubbles or unfilled areas. After the slurry injection was completed, a curing treatment was performed to form a continuous and dense graphene nano-ceramic slurry cured layer within the pores.

[0034] Thus, the metal skeleton of the foamed copper matrix is ​​tightly bonded to the internally filled graphene nano-ceramic solidified layer, forming a unified whole. This composite structure allows the overall density of the heat sink to be controlled at around 2.5 g / cm³, significantly lower than that of pure copper heat sinks, meeting the lightweight requirements of servers. Simultaneously, because the graphene nano-ceramic solidified layer provides an efficient heat conduction path and eliminates the heat dissipation bottleneck caused by the hollow pores of traditional foamed metal, the overall thermal conductivity of the composite heat sink reaches 1300 W / m³. K and above.

[0035] When the server generates heat during operation, the heat is rapidly transferred to the composite heatsink. First, the heat is absorbed by the metal framework of the copper foam matrix and quickly diffuses. Simultaneously, the heat is rapidly conducted to the external surface of the heatsink along a highly efficient thermally conductive network through the graphene nanoceramic solidified layer tightly bonded to the metal framework, and ultimately dissipated into the environment. This synergistic effect ensures that heat is quickly and evenly conducted away from the heat source, effectively reducing the server's operating temperature and ensuring its stable and efficient operation.

[0036] Based on the above examples, the graphene foam copper composite heat sink proposed in this application demonstrates significant technological contributions.

[0037] Compared to traditional pure copper heat sinks, this application utilizes foamed copper or foamed aluminum as a porous matrix, combined with a highly thermally conductive filling layer, to significantly reduce the overall density of the heat sink while maintaining or even improving its thermal conductivity. For example, in the aforementioned server cooling scenario, while traditional pure copper heat sinks offer good thermal conductivity, their high density increases the overall weight of the device, limiting their application in lightweight devices. The composite heat sink of this application achieves a balance between lightweight design and high thermal conductivity with a density of approximately 2.5 g / cm³.

[0038] Compared to pure aluminum or aluminum alloy heat sinks, the composite heat sink of this application has a significant advantage in thermal conductivity. While pure aluminum heat sinks are lightweight, their thermal conductivity is often insufficient to meet the demands of rapid heat dissipation in high-power applications, and they are prone to surface oxidation and corrosion, leading to performance degradation over long-term use. This application improves the overall thermal conductivity to 1300 W / m by filling a porous matrix with a graphene nano-ceramic slurry curing layer. With a K value exceeding that of pure aluminum, it effectively solves the heat dissipation bottleneck of high-power equipment.

[0039] Furthermore, addressing the common problems of high interfacial thermal resistance, coating peeling, and insufficient filling in existing composite heat sinks, this application effectively eliminates interfacial gaps and voids by continuously and densely filling the pores of a porous matrix with a graphene nano-ceramic slurry curing layer. In the above example, the thorough wetting and curing of the slurry ensures a tight bond between the foamed copper matrix and the filling layer, significantly reducing interfacial thermal resistance and guaranteeing the continuity and stability of heat conduction. This avoids the performance instability and low yield problems caused by interfacial issues in traditional composite coated heat sinks.

[0040] Therefore, the composite heat sink of this application not only solves the problems of low thermal conductivity, heavy weight, high interfacial thermal resistance and insufficient heat dissipation caused by hollow pores, but also provides a heat dissipation solution with stable structure, reliable performance and longer life, which plays an important role in promoting the advancement of heat dissipation technology in fields such as high-power electronic devices and new energy equipment.

[0041] In some of the solutions described above in this application, foamed copper is proposed as a porous matrix to achieve a lightweight and high thermal conductivity heat sink. However, in the process of its implementation, if the porosity and pore size of the foamed copper are not appropriate, it may lead to problems such as insufficient slurry filling, increased interfacial thermal resistance, unstable thermal conductivity, or poor lightweight effect.

[0042] In this regard, this application further proposes that the porous matrix is ​​copper foam, the porosity of the copper foam is 75% to 90%, and the pore size of the copper foam is 0.5 to 5 mm.

[0043] Copper foam is a copper material with a three-dimensional interconnected porous structure, characterized by excellent thermal conductivity, high mechanical strength, and a certain degree of plasticity. As a porous matrix, it provides skeletal support and thermal conduction channels for subsequent slurry filling. It can be prepared through processes such as electrodeposition, sintering, or melt foaming.

[0044] Porosity refers to the percentage of pore volume in copper foam relative to the total volume. This parameter directly affects the lightweight nature, mechanical strength, and filling amount and effect of the slurry in copper foam. For example, porosity can be controlled by adjusting the amount of foaming agent, sintering temperature, or electrodeposition parameters in the preparation process. In addition to the 75%–90% range, other porosities, such as 60%–75% or 90%–95%, can be achieved by adjusting process parameters, but these ranges may involve different trade-offs in terms of lightweighting, strength, and filling effect.

[0045] Pore ​​size refers to the average diameter or size range of the pores inside the copper foam. This parameter has a critical impact on the permeability of the slurry, the uniformity of filling, and the thermal conductivity and interfacial thermal resistance of the final composite material. Pore size can be controlled by adjusting the template size, foaming agent particle size, or sintering particle size during the preparation process. In addition to the range of 0.5–5 mm, other pore sizes, such as 0.1–0.5 mm or 5–10 mm, can be achieved by adjusting process parameters, but these ranges may present different challenges in terms of slurry penetration, bubble retention, and the continuity of the thermal conductivity path.

[0046] This application optimizes the structural parameters of the composite heat sink by specifically defining the porous matrix as copper foam and precisely controlling its porosity between 75% and 90%, while limiting the pore size of the copper foam to within the range of 0.5 to 5 mm. As a porous matrix, copper foam, with its inherent high thermal conductivity and good mechanical strength, provides a solid foundation and efficient thermally conductive framework for the subsequent filling of graphene nano-ceramic slurry. By setting the porosity to 75%–90%, sufficient lightweight characteristics of the copper foam matrix are ensured, while ample filling space for the slurry is provided. This avoids insufficient slurry filling due to excessively low porosity, which would affect the overall thermal conductivity, and also avoids the problem of excessively high porosity potentially weakening the matrix's own support. Simultaneously, controlling the pore size to 0.5–5 mm effectively promotes the uniform flow and full penetration of the graphene nano-ceramic slurry within the porous matrix pores, ensuring that the slurry can continuously and densely fill the entire pore structure, thereby significantly reducing interfacial gaps and bubble formation. This precise structural control enables a tight bond between the graphene nano-ceramic slurry curing layer and the foamed copper matrix, minimizing interfacial thermal resistance and ensuring that heat can be efficiently transferred from the foamed copper skeleton to the slurry curing layer, and then further conducted through the slurry curing layer, ultimately improving the overall thermal conductivity and structural stability of the composite heat sink.

[0047] In one specific implementation, the porous matrix can be selected from copper foam prepared by electrodeposition, with a porosity controlled at approximately 80% and a pore size controlled between approximately 1 mm and 3 mm. During the preparation process, copper powder is first mixed with a foaming agent and sintered to form a copper foam preform with a specific pore structure. Subsequently, the copper foam preform is cut and shaped by machining or chemical etching to achieve the preset size and structure. In the subsequent slurry filling stage, this copper foam matrix with specific porosity and pore size ensures that the graphene nanoceramic slurry is fully injected and uniformly wetted under vacuum, thereby forming a continuous and dense composite structure after curing.

[0048] Through the above technical solution, this application effectively solves the problems in the prior art where improper porosity and pore size of the porous copper foam matrix lead to insufficient slurry filling, increased interfacial thermal resistance, unstable thermal conductivity, or poor weight reduction. By precisely limiting the porosity of the copper foam to between 75% and 90% and the pore size to between 0.5 and 5 mm, the porous matrix provides ideal filling space and penetration channels for the graphene nano-ceramic slurry while maintaining lightweight properties. This not only ensures that the slurry can fully and uniformly fill the pores of the porous matrix to form a continuous and dense cured layer, but also significantly reduces interfacial thermal resistance and improves heat transfer efficiency. Therefore, the composite heat sink of this application achieves high thermal conductivity while also considering lightweight and structural stability, and can better meet the needs of high-efficiency heat dissipation in fields such as new energy equipment and high-precision electronic instruments.

[0049] In some embodiments described above, aluminum foam is proposed as the porous matrix to provide a lightweight porous structure. However, if the porosity and pore size of the aluminum foam are not controlled during its implementation, it may lead to insufficient filling, unstable thermal conductivity, or insufficient structural strength. Therefore, this application further proposes aluminum foam as the porous matrix, with a porosity of 60%–85% and a pore size of 1–8 mm.

[0050] Aluminum foam is a lightweight metallic material with a porous structure, consisting of interconnected or closed pores internally and an aluminum matrix framework externally. This material has attracted attention due to its low density, high specific strength, high specific surface area, and excellent energy absorption characteristics. As a porous matrix for heat sinks, aluminum foam can provide ample space for filling highly thermally conductive materials while maintaining a lightweight overall structure. Its preparation methods include melt foaming, powder metallurgy, and impregnation. By controlling process parameters, aluminum foam with different pore structures and properties can be obtained. Porosity refers to the percentage of pore volume in the total volume of aluminum foam. Limiting the porosity of aluminum foam to the range of 60%–85% aims to achieve a balance between lightweighting, structural stability, and slurry filling efficiency. For example, when the porosity is close to 60%, the framework structure of aluminum foam is more dense, providing higher mechanical strength, but the space available for slurry filling is relatively limited; while when the porosity is close to 85%, the lightweighting effect of aluminum foam is more significant, and the space available for slurry filling is larger, but its structural strength may be relatively reduced. By precisely controlling the porosity within this range, it is possible to ensure sufficient filling space while maintaining the necessary structural support capacity of the porous matrix. Pore size refers to the average size of the pores within the aluminum foam. Limiting the pore size of the aluminum foam to the range of 1–8 mm optimizes the permeability and filling density of the graphene nano-ceramic slurry. For example, when the pore size is small (close to 1 mm), the slurry may encounter greater flow resistance during permeation, but the contact area between the cured layer and the matrix after filling may be more uniform. When the pore size is large (close to 8 mm), the slurry has better permeability and can fill quickly, but excessively large pore sizes may cause sedimentation or unevenness during curing. This range helps the slurry fully wet the interior of the porous matrix, reducing the generation of bubbles and interface defects, thereby reducing interfacial thermal resistance and improving overall thermal conductivity.

[0051] This application proposes a graphene-copper foam composite heat sink, the core of which lies in using copper foam or aluminum foam as a porous matrix, with a solidified graphene nano-ceramic slurry layer filled within its pores. To further optimize the performance of the composite heat sink, this application specifically defines the porous matrix as aluminum foam, and precisely controls its porosity and pore size specifications. As a porous matrix, aluminum foam's inherent lightweight properties significantly reduce the overall density of the heat sink, meeting the requirement for lightweight equipment. Simultaneously, the high specific surface area of ​​aluminum foam provides ample space for the adhesion and filling of the graphene nano-ceramic slurry. By controlling the porosity of the aluminum foam within the range of 60% to 85%, it ensures that the porous matrix has sufficient pore space to accommodate the highly thermally conductive slurry while maintaining necessary structural strength, avoiding structural fragility due to excessive porosity or insufficient filling due to excessively low porosity. Furthermore, by limiting the pore size of the aluminum foam to 1–8 mm, the graphene nano-ceramic slurry can fully and uniformly penetrate into every micropore of the porous matrix, effectively avoiding problems such as insufficient slurry filling, residual air bubbles, and interfacial gaps. This precisely controlled pore structure, combined with the excellent thermal conductivity of the graphene nano-ceramic slurry, allows for a continuous and dense bond between the slurry curing layer and the aluminum foam matrix, significantly reducing interfacial thermal resistance and ensuring the overall high thermal conductivity of the composite heat sink. Therefore, by optimizing the porosity and pore size of the porous aluminum foam matrix, the composite heat sink of this application significantly improves thermal conductivity and structural stability while maintaining lightweight design, effectively addressing the shortcomings of traditional heat sinks in terms of lightweight design, thermal conductivity, and structural stability.

[0052] As a specific implementation method, the porous matrix can be aluminum foam prepared by melt foaming, with a porosity controlled at around 70% and an average pore size controlled at around 3 mm. This aluminum foam matrix has a uniform pore distribution and good connectivity, providing an ideal internal structure for the subsequent injection and curing of graphene nanoceramic slurry. In actual operation, the porosity and pore size of the aluminum foam can be precisely controlled by adjusting process parameters such as the type and amount of foaming agent, as well as the foaming temperature and time, to meet design requirements.

[0053] The above technical solution explicitly defines the porous matrix as aluminum foam and precisely controls its porosity and pore size, effectively solving the problems of insufficient filling, unstable thermal conductivity, and insufficient structural strength that may occur during the filling process of porous matrices. Specifically, the defined porosity range of the aluminum foam ensures that the slurry has sufficient space to fill while maintaining the structural integrity of the matrix; the defined pore size promotes uniform penetration and dense filling of the slurry, significantly reducing interface defects and bubble generation. This allows the graphene nano-ceramic slurry curing layer to form a tight bond with the aluminum foam matrix, greatly reducing interfacial thermal resistance and ensuring the overall high thermal conductivity and long-term stability of the composite heat sink. Therefore, the composite heat sink of this application achieves lightweighting while significantly improving thermal conductivity and structural reliability, better meeting the heat dissipation needs of high-power equipment such as new energy devices and high-precision electronic instruments.

[0054] In some embodiments described above, a graphene nano-ceramic slurry curing layer is proposed to fill the pores of a porous substrate to improve the thermal conductivity of the composite heat sink. However, during its implementation, problems such as discontinuous filling, voids, or interface gaps may exist, leading to increased thermal resistance, coating peeling, and unstable heat dissipation performance. To address this, this application further proposes that the graphene nano-ceramic slurry curing layer continuously and densely fills the pores of the porous substrate, and that there are no voids or interface gaps between the graphene nano-ceramic slurry curing layer and the porous substrate.

[0055] To achieve the above technical solution, firstly, regarding the "continuous and dense filling of the graphene nano-ceramic slurry curing layer within the pores of the porous matrix," the core lies in ensuring that the slurry can uniformly and uninterruptedly penetrate and fill all the pores inside the porous matrix, avoiding the formation of any voids or bubbles, thereby ensuring the integrity and efficiency of the heat conduction path. Specifically, this can be achieved by optimizing the rheological properties of the slurry, such as adjusting its viscosity and thixotropy, to give it good flowability and permeability. Simultaneously, during the slurry injection process, a high vacuum environment can be used, and the injection pressure and speed can be precisely controlled to promote full wetting of the slurry and expel gas from the pores. As another approach, the porous matrix can also undergo surface pretreatment, such as hydrophilication or plasma treatment, to enhance the wettability between the matrix and the slurry, thereby promoting the uniform spreading and filling of the slurry within the pores.

[0056] Secondly, regarding the "pore-free graphene nano-ceramic slurry curing layer and porous matrix," the aim is to ensure that the cured slurry layer contains no macroscopic or microscopic voids, maintaining the continuity of the heat-conducting medium and preventing heat from being blocked at pores. This can be achieved through precise control of the slurry formulation; for example, selecting components with minimal volatile matter generation during curing and employing optimized curing temperature and time profiles to avoid internal stress or gas retention leading to pore formation due to excessively rapid curing. Furthermore, a multi-stage curing process can be used, with slow heating and holding to allow sufficient time for gas to escape from the slurry and ensure uniform curing, thereby effectively suppressing pore formation.

[0057] Furthermore, regarding the "no interfacial gap between the graphene nano-ceramic slurry curing layer and the porous substrate," the key lies in ensuring a tight, seamless bond between the curing layer and the porous substrate, eliminating any tiny voids or delamination. This minimizes interfacial thermal resistance and ensures efficient heat transfer from the substrate to the curing layer. This can be achieved by selecting a slurry system with good wettability and adhesion to the porous substrate. For example, the organic binder in the slurry should have good chemical compatibility or physical adsorption capacity with the substrate material. Alternatively, the porous substrate can be surface-activated before slurry injection, such as through acid washing, alkali washing, or plasma treatment, to increase the active sites on the substrate surface, promoting bonding with the slurry and thus forming a strong, gapless interface.

[0058] The solution presented in this application aims to construct a highly efficient and stable heat conduction network through the aforementioned technical means. In composite heat sinks using copper foam or aluminum foam as the porous matrix, the porous matrix itself provides a lightweight, high specific surface area framework structure. When a graphene nano-ceramic slurry curing layer is introduced and fills these pores, its thermal conductivity becomes crucial. By ensuring continuous and dense filling of the slurry within the pores of the porous matrix, interruptions in the heat conduction path or increased thermal resistance due to incomplete filling or the presence of voids can be effectively avoided. Simultaneously, the absence of pores within the curing layer ensures the uniformity and continuity of the heat-conducting medium, allowing heat to be transferred smoothly and unimpeded within the graphene nano-ceramic network. More importantly, the absence of interfacial gaps between the graphene nano-ceramic slurry curing layer and the porous matrix significantly reduces interfacial thermal resistance, ensuring that heat can be efficiently and losslessly transferred from the porous matrix to the curing layer and further dissipated outwards. This tight bonding and continuous filling enable the porous matrix and the highly thermally conductive graphene nano-ceramic slurry curing layer to form a synergistic, integrated thermal conductivity system. This overcomes the problem of limited thermal conductivity in traditional foam metal radiators due to hollow pores, and also avoids the performance instability caused by interface defects in traditional composite materials.

[0059] As a specific implementation method, the following approach can be used to achieve continuous, dense filling, pore-free, and interfacial gap-free curing of graphene nano-ceramic slurry within the pores of a porous matrix. First, during slurry preparation, the ratio of graphene powder, nano-ceramic powder, organic binder, and deionized water is precisely controlled to ensure the slurry has suitable viscosity and surface tension, facilitating its full penetration and spreading within the porous matrix pores. During the filling process, vacuum-assisted impregnation technology can be employed. The porous matrix is ​​placed in a low-pressure environment, and the slurry is slowly introduced. The pressure difference allows the slurry to fully wet the pores and expel air, thus achieving continuous, dense filling. After slurry injection, appropriate settling treatment can be performed to further stabilize the slurry within the pores and allow microbubbles to escape, preventing the formation of pores after curing. Subsequently, during the curing stage, a precisely controlled temperature profile is used, for example, through slow heating and multi-stage heat preservation, to ensure uniform curing of the slurry and avoid internal stress or gas encapsulation caused by rapid curing, thereby ensuring a pore-free cured layer. Meanwhile, the organic binder in the slurry has good chemical compatibility with the porous matrix material, forming a strong chemical bond or physical adsorption during the curing process, thereby ensuring a tight bond between the cured layer and the porous matrix and eliminating interfacial gaps.

[0060] Through the above technical solution, this application effectively solves the problems of increased thermal resistance, coating peeling, and unstable heat dissipation performance caused by discontinuous filling, pores, or interfacial gaps in existing composite heat sinks. Specifically, the continuous and dense filling of the graphene nano-ceramic slurry curing layer within the pores of the porous matrix ensures the integrity and efficiency of the heat transfer path, avoiding heat accumulation caused by voids. The absence of pores within the curing layer further ensures the uniformity and continuity of the heat-conducting medium, eliminating internal thermal resistance. More importantly, the absence of interfacial gaps between the curing layer and the porous matrix significantly reduces interfacial thermal resistance, ensuring that heat can be efficiently and without damage transferred from the matrix to the curing layer, thereby significantly improving the overall thermal conductivity and thermal management efficiency of the composite heat sink. This optimized filling structure not only improves the stability of the heat sink's thermal conductivity but also enhances the bonding strength between the curing layer and the matrix, effectively preventing coating peeling and extending the service life of the heat sink.

[0061] In some of the solutions mentioned above in this application, a composite radiator overall structure is proposed to achieve efficient heat dissipation. However, in this process, the structural shape of the radiator is not clearly defined, which may result in the heat dissipation efficiency not being optimized for different equipment spaces and heat dissipation needs, thereby affecting installation compatibility and heat conduction uniformity.

[0062] In this regard, this application further proposes that the overall structure of the composite heat sink can be any one of plate-shaped, column-shaped, fin-shaped, or honeycomb-shaped.

[0063] Specifically, a plate-like structure refers to a heat sink that is flat and plate-like. This structure typically has a large surface area, providing a uniform heat conduction path, and is suitable for scenarios requiring large-area contact heat dissipation, such as the base plate or casing of electronic devices. It can be achieved through integral casting or by cutting and machining composite material sheets. A columnar structure refers to a heat sink that is cylindrical or polygonal in shape. This structure is suitable for applications with limited space or requiring heat flow in a specific direction, such as heat dissipation from a point heat source or heat exchange within a pipe. It can be achieved through extrusion molding, die casting, or machining. A finned structure refers to a heat sink with extended, thin fin-like structures designed to significantly increase the contact surface area with the surrounding medium (such as air), thereby improving convective heat transfer efficiency. Fins can be upright, wavy, needle-like, or staggered. This structure is particularly suitable for high-power devices to achieve rapid and efficient heat dissipation. It can be achieved by connecting the fins to the substrate through integral molding, welding, or pressing. A honeycomb structure refers to a radiator's internal or overall structure consisting of multiple interconnected holes, resembling a honeycomb. This structure offers advantages such as lightweight and high strength, large specific surface area, and low fluid resistance, providing efficient heat transfer channels while maintaining low density. It can be achieved through special molding, sintering, or combining prefabricated honeycomb core materials with composite materials.

[0064] The core of the composite heat sink proposed in this application lies in using copper foam or aluminum foam as a porous matrix, and filling the pores with a solidified graphene nano-ceramic slurry layer, thereby forming a composite material with both high thermal conductivity and lightweight properties. Based on this, by designing the overall structure of the composite heat sink into any of the following forms—plate, column, fin, or honeycomb—the excellent performance of the composite material can be fully utilized, and it can be optimized for different application scenarios and heat dissipation requirements. Specifically, when a composite radiator adopts a plate-like structure, its large flat surface can closely fit the heat source, achieving efficient and uniform heat conduction, suitable for heat dissipation from planar heat sources. When a columnar structure is adopted, its compact volume and specific shape allow it to adapt to narrow spaces or serve as a heat dissipation component for point heat sources, optimizing space utilization and heat flow direction. When a finned structure is adopted, the convective heat transfer efficiency is significantly improved by greatly increasing the contact surface area with the environment, making it particularly suitable for the rapid heat dissipation of high-power equipment. When a honeycomb structure is adopted, it provides a high specific surface area and good structural stability while maintaining lightweight design, ensuring uniform heat dissipation and overall strength. These structural choices maximize the performance of high thermal conductivity lightweight composite materials, ensuring that heat can be efficiently and uniformly transferred and dissipated from the heat source, thus effectively solving the problem that heat dissipation efficiency cannot be optimized for different equipment spaces and heat dissipation requirements.

[0065] As a specific implementation method, the aforementioned graphene foam copper composite heat sink can be fabricated into a finned structure. For example, in the heat dissipation system of battery modules in new energy vehicles, a composite material formed by using foam copper as a porous matrix and filling it with a graphene nano-ceramic slurry solidification layer can be used to fabricate a heat sink with dense fins through integral molding or precision machining. These fins can be designed as upright or wave-shaped to maximize the contact area with cooling air. When the battery module generates a large amount of heat during operation, the heat is first rapidly conducted to the fins through the high thermal conductivity of the composite material, and then efficiently transferred away through convective heat exchange between the fins and the flowing air. This finned structure fully utilizes the high thermal conductivity and lightweight properties of the composite material, achieving extremely high heat dissipation efficiency within a limited installation space. As another example, in the CPU cooling of high-performance servers, a plate-shaped composite heat sink can be used as a heat spreader. The plate-like structure uses aluminum foam as a porous matrix and is filled with a graphene nano-ceramic slurry solidification layer. Its flat surface is in close contact with the CPU top cover, which can quickly and evenly diffuse the local high heat generated by the CPU to the entire plate-like heat sink surface, and then further dissipate heat through other heat dissipation components (such as fans or liquid cooling systems).

[0066] Through the aforementioned technical solution, this application clearly defines the overall structure of the composite radiator, allowing for flexible selection of the most suitable structural form based on specific application scenarios and equipment space requirements. This structural optimization fully leverages the performance of the high thermal conductivity lightweight composite material, significantly improving heat dissipation efficiency and heat conduction uniformity. For example, plate-like structures achieve large-area uniform heat dissipation, columnar structures are suitable for point heat sources or narrow spaces, finned structures greatly increase the heat dissipation surface area to cope with high heat flux density, while honeycomb structures achieve a good balance between lightweight and structural strength. Therefore, the solution of this application effectively solves the problems of poor heat dissipation efficiency, poor installation adaptability, and uneven heat conduction caused by the single structure of traditional radiators in different equipment, greatly improving the versatility and application range of radiators, and ensuring the stability and reliability of equipment operation under various complex working conditions.

[0067] In some of the solutions described above in this application, a graphene nano-ceramic slurry curing layer is proposed to fill the pores of a porous matrix and cure it to achieve high thermal conductivity and lightweight properties. However, during its implementation, improper slurry composition may lead to problems such as insufficient filling, weak interfacial bonding, and uneven curing. To address this, this application further proposes that the graphene nano-ceramic slurry curing layer is composed of graphene powder, nano-ceramic powder, organic binder, and deionized water; wherein the graphene powder content is 3%–10 wt%, and the nano-ceramic powder content is 15%–25 wt%.

[0068] Graphene powder, as a crucial component of the slurry, plays a key role in providing excellent thermal conductivity. Graphene itself possesses extremely high intrinsic thermal conductivity, and its introduction into composite materials can significantly improve the overall thermal conductivity of the material. For example, reduced graphene oxide powder with high specific surface area and good dispersibility can be selected, or high-purity graphene micro-flake powder prepared by mechanical exfoliation or chemical vapor deposition can be used. Nano-ceramic powders in the slurry mainly enhance mechanical properties and improve the stability and density of the cured layer. Nanoscale ceramic particles can be uniformly dispersed in the slurry, forming a dense skeletal structure after curing, effectively preventing cracking or detachment of the cured layer and helping to reduce interfacial thermal resistance. For example, aluminum nitride nanoparticles, boron nitride nanoparticles, or alumina nanoparticles can be selected, as these materials themselves also possess good thermal conductivity. Organic binders play a crucial connecting role in the slurry, effectively bonding the graphene powder and nano-ceramic powder together and ensuring good flowability and wettability of the slurry within the pores of the porous matrix. After curing, the organic binder forms a continuous matrix, fixing the thermally conductive filler and creating a strong interfacial bond with the porous matrix. For example, polymers with good adhesion and thermal stability, such as epoxy resin, polyimide resin, or phenolic resin, can be selected. Deionized water is used as the solvent in the slurry, its main function being to ensure the uniform dispersion and mixing of graphene powder, nano-ceramic powder, and organic binder, forming a slurry with appropriate viscosity and flowability. Using deionized water avoids the introduction of impurity ions, thus ensuring the purity of the slurry and the performance stability of the cured layer. Alternatively, other polar solvents such as ethanol or isopropanol can be used as auxiliary dispersion media as needed, without affecting the slurry performance. Controlling the graphene powder content within the range of 3% to 10 wt% aims to optimize the balance between the slurry's thermal conductivity and workability. Below this range, the improvement in thermal conductivity may be insignificant, while above this range, the slurry viscosity may be too high, making it difficult to fully wet and fill the micropores of the porous matrix, and even affecting the uniformity of the cured layer. The content of nano-ceramic powder is set in the range of 15% to 25 wt% to ensure that the cured layer has sufficient strength and density, while maintaining the fluidity of the slurry. Within this content range, the nano-ceramic particles can form an effective supporting structure, reduce curing shrinkage, and prevent the formation of residual bubbles or interfacial gaps in the pores, thereby enhancing the bonding strength and overall stability between the cured layer and the porous matrix.

[0069] This application achieves continuous and dense filling of a slurry within the pores of a porous matrix by precisely controlling the compounding ratio of graphene powder, nano-ceramic powder, organic binder, and deionized water. Specifically, the graphene powder, as a highly thermally conductive filler, forms a continuous thermally conductive network after the slurry solidifies, significantly improving the thermal conductivity of the solidified layer. The nano-ceramic powder, as a reinforcing phase, with its nanoscale size, allows for uniform dispersion and forms a dense skeletal structure during solidification, effectively suppressing solidification shrinkage and improving the mechanical strength and stability of the solidified layer, thus preventing cracking or detachment. The organic binder firmly bonds the graphene powder and nano-ceramic powder together and ensures good flowability and wettability of the slurry when injected into the porous matrix, allowing it to fully penetrate every micropore of the porous matrix. Deionized water, as a solvent, ensures the uniform dispersion and purity of the slurry components. By controlling the graphene powder content to 3%–10 wt%, sufficient thermal conductivity is ensured while avoiding filling difficulties caused by excessively high slurry viscosity. Simultaneously, controlling the nano-ceramic powder content to 15%–25 wt% ensures the density of the cured layer and the interfacial bonding strength, effectively preventing the formation of residual air bubbles and interfacial gaps. This precisely proportioned slurry, after filling the porous matrix, forms a continuous, dense cured layer without pores or interfacial gaps, significantly reducing interfacial thermal resistance. This solves the problems of unstable heat dissipation performance caused by insufficient filling, weak interfacial bonding, and uneven curing in traditional composite heat sinks, resulting in a substantial improvement in the overall thermal conductivity of the composite heat sink while maintaining its lightweight characteristics.

[0070] As a specific implementation method, the graphene nano-ceramic slurry curing layer can be prepared by compounding the following components: 5 wt% of reduced graphene oxide powder with an average particle size of 500 nm; 20 wt% of aluminum nitride nanoparticles with an average particle size of 80 nm; 15 wt% of a low-viscosity epoxy resin as an organic binder; and the remainder being deionized water. In the preparation process, the nano-ceramic powder and deionized water are first mixed and then ultrasonically dispersed to achieve uniform dispersion. Next, the organic binder is added and stirred. Finally, the graphene powder is slowly added and fully dispersed under high-speed shear stirring to form a uniform and stable slurry. This slurry exhibits good fluidity, effectively wetting the pores of the porous matrix, and forms a dense cured layer with high thermal conductivity and high strength after curing.

[0071] Through the above technical solution, this application effectively solves problems such as insufficient slurry filling, weak interfacial bonding, and uneven curing by optimizing the composition and content of the graphene nano-ceramic slurry curing layer. Specifically, the precisely controlled graphene powder content ensures the formation of a highly efficient thermally conductive network within the curing layer, significantly improving overall thermal conductivity. The introduction and optimization of the content of nano-ceramic powder endow the curing layer with excellent mechanical strength and structural stability, effectively suppressing curing shrinkage and eliminating interfacial gaps and bubbles, thereby ensuring a continuous and dense bond between the curing layer and the porous matrix. The reasonable ratio of organic binder and deionized water further ensures good fluidity and uniformity of the slurry, allowing it to fully wet and fill all the pores of the porous matrix. This optimized slurry curing layer is tightly bonded to the porous matrix, greatly reducing interfacial thermal resistance. This enables the composite heat sink to achieve high thermal conductivity while maintaining lightweight characteristics, significantly improving heat dissipation efficiency and service life, and meeting the high requirements of heat sinks for new energy equipment, high-precision electronic instruments, and high-power semiconductor devices.

[0072] In traditional composite heat sink manufacturing processes, the lack of effective methods for bubble elimination and dense filling often leads to problems such as interfacial gaps, bubbles, and incomplete filling, resulting in unstable overall thermal conductivity and low yield. While some embodiments of this application propose the fabrication of graphene foam copper composite heat sinks, ensuring complete and dense filling of the porous matrix remains a critical technical challenge.

[0073] Example 2: like Figure 1 ~as Figure 3 As shown, this application further proposes a method for preparing a graphene foamed copper composite heat sink, which includes the following steps: First, a porous matrix of foamed copper or foamed aluminum with matching specifications is selected and processed to a preset size and structural specification through cutting and shaping processes, removing burrs, oxide layers, and impurities in the pores of the porous matrix surface; Second, the processed porous matrix is ​​flattened into a customized molding mold, and the mold cavity is sealed after positioning and fixing; Next, the mold cavity is evacuated to 10°C. - ¹Pa vacuum, after holding pressure for 3–10 minutes, graphene nano-ceramic slurry is uniformly injected into the mold to completely impregnate and fill the pores of the porous matrix. Then, the porous matrix with the injection completed, along with the molding mold, is placed into a drying equipment and dried and cured at a constant temperature to obtain a preliminary composite matrix. Subsequently, the surface of the dried and cured composite matrix is ​​finely processed and protected to remove residual slurry and defects, finally obtaining a composite heat sink. Finally, the thermal conductivity, density, and appearance accuracy of the processed composite heat sink are tested. After passing the tests, it is dust-removed and packaged.

[0074] The solution of this application is achieved through 10 - The pressure-holding treatment under an ultra-high vacuum environment (¹Pa) effectively eliminates air within the mold cavity, preventing bubble formation. Simultaneously, the uniform injection of graphene nano-ceramic slurry ensures that the slurry fully wets and completely fills the pores of the porous matrix, avoiding the problem of incomplete filling. Furthermore, the porous matrix, along with the molding mold, is dried and cured as a whole, avoiding interfacial stress that might occur during separation operations and ensuring a tight bond between the slurry and the matrix. Specifically, the vacuum environment eliminates residual gas within the pores, allowing the slurry to more easily penetrate into the micropores under negative pressure; the uniform injection process controls the slurry flow rate, preventing turbulence and bubble entrainment due to excessive flow; and the overall curing treatment maintains the stability of the contact interface between the slurry and the matrix, avoiding the shrinkage stress concentration caused by traditional step-by-step curing. Through these technical solutions, the problems of interfacial gaps, bubbles, and incomplete filling in the traditional composite heat sink manufacturing process are successfully solved, ensuring the stable performance and high thermal conductivity of the graphene foam copper composite heat sink.

[0075] For example, in the fabrication of heat sinks for high-power semiconductor devices, aluminum foam is used as a porous matrix with a porosity controlled at 75%. After the processed matrix is ​​placed into a mold, a vacuum is drawn to 10... - The pressure was maintained at ¹Pa for 5 minutes, followed by uniform injection of graphene nano-ceramic slurry at a rate of 0.5 mL / s. The slurry completely wetted the pores under vacuum assistance, with no residual bubbles. After overall drying and curing, the composite substrate underwent surface finishing to remove excess slurry. The final product achieved a thermal conductivity of 1250 W / m·K and a density of 2.3 g / cm³. Testing showed that the interfacial thermal resistance was reduced by 85% compared to traditional coating processes, and the product yield increased to over 98%. This embodiment verifies the significant effect of the method in eliminating interfacial defects and achieving dense filling, providing a reliable technical guarantee for heat dissipation in high-power equipment.

[0076] In some embodiments described above in this application, a drying and curing step is proposed to cure the graphene nano-ceramic slurry within the pores of the porous matrix. However, if the temperature, time, or heating rate is not properly controlled during its implementation, the slurry may not cure sufficiently, leaving residual bubbles and increasing the interfacial gaps, thereby affecting the thermal conductivity and structural stability of the composite heat sink and reducing the product yield.

[0077] In this regard, this application further proposes that in step 4 above, the drying and curing temperature is 50-150℃, the drying and curing time is 6-13h, and the drying process adopts a segmented heating mode with a heating rate of 2-5℃ / min.

[0078] The drying and curing temperature is 50–150°C, designed to provide a suitable thermosetting environment for the graphene nano-ceramic slurry. This temperature range ensures that the organic binder in the slurry undergoes a full polymerization reaction to form a stable cross-linked structure, while avoiding material degradation due to excessively high temperatures or incomplete curing due to excessively low temperatures. This temperature can be achieved using various heating devices, such as a precisely temperature-controlled electric blast oven or radiant heating with an infrared heating device to reach the required temperature conditions.

[0079] The drying and curing time is 6–13 hours to ensure that the slurry has sufficient time to complete the curing reaction. Within this time range, the chemical reaction in the slurry can proceed fully, ensuring that the cured layer achieves the expected mechanical strength and thermal stability, and avoiding the formation of uncured areas or weak points due to insufficient curing time. This time can be precisely controlled by a programmable timer integrated into the heating equipment, or dynamically adjusted by real-time monitoring of the slurry's curing status (e.g., through viscosity changes or hardness tests).

[0080] The drying process employs a segmented heating mode, meaning that the temperature does not reach its maximum point all at once during the entire curing process, but rather increases gradually in stages, maintaining certain temperature points for a period of time. This mode effectively reduces the impact of thermal stress on the material, preventing the formation of bubbles or microcracks within the slurry due to sudden temperature changes, while simultaneously promoting uniform evaporation of the solvent in the slurry, preventing surface skinning or internal defects. The segmented heating mode can be implemented through a preset temperature profile program in the oven controller, or by manually adjusting the heating power and time interval.

[0081] The heating rate is 2–5 °C / min, used to control the rate of temperature rise. A gradual heating rate helps heat to be transferred evenly to the porous matrix and the interior of the slurry, avoiding localized overheating or undercooling, thereby reducing the temperature gradient and thermal stress within the material. This is crucial for preventing stress concentration, microcracks, or delamination at the interface between the slurry and the porous matrix. The heating rate is typically determined by the power output of the heating equipment and the temperature feedback control system to ensure the stability and controllability of the heating process.

[0082] This application's solution achieves uniform and thorough curing of the graphene nano-ceramic slurry injected into the porous matrix by precisely controlling the temperature, duration, heating mode, and heating rate of the drying and curing process. Throughout the curing process, a suitable temperature range and sufficient curing time ensure the complete chemical reaction within the slurry, resulting in a dense and stable cured layer. Simultaneously, the segmented heating mode and controlled heating rate work synergistically to effectively alleviate thermal stress that may occur during heating, preventing bubble formation due to rapid solvent evaporation and microcracks or interface defects caused by excessive temperature gradients. This refined curing process ensures a tight, gapless bond between the cured graphene nano-ceramic slurry layer and the porous matrix, thereby minimizing interfacial thermal resistance and guaranteeing the high thermal conductivity and excellent structural stability of the composite heat sink.

[0083] In one specific implementation, in step 4 above, the porous substrate after injection molding, along with the molding die, can be placed into an oven equipped with precise temperature control and programmed temperature rise. The drying and curing process can be set as follows: First, the temperature is increased from room temperature to 60°C at a rate of 3°C / min, and held at this temperature for 2 hours to promote the slow evaporation of organic solvents in the slurry. Subsequently, the temperature is increased to 120°C at a rate of 2°C / min and held at this temperature for 5 hours to ensure that the binder in the graphene nano-ceramic slurry is fully cured and forms a stable cross-linked structure. Finally, the temperature is further increased to 140°C at a rate of 3°C / min and held for 3 hours to complete the final curing and stress release. The entire drying and curing process takes 10 hours, and a segmented temperature rise mode is used throughout, with the temperature rise rate controlled within the range of 2–5°C / min.

[0084] By precisely controlling the temperature, duration, and heating mode of the drying and curing process using the above technical solutions, problems such as insufficient curing of the slurry, residual air bubbles, and interfacial gaps can be effectively avoided. This ensures that the cured graphene nano-ceramic slurry layer continuously and densely fills the pores of the porous matrix, forming a tight bond with the porous matrix without pores or interfacial gaps. This significantly reduces interfacial thermal resistance, improves the overall thermal conductivity and structural stability of the composite heat sink, and ultimately increases the product yield and service life, enabling it to better meet the heat dissipation needs of high-power equipment such as new energy devices and high-precision electronic instruments.

[0085] In some of the solutions mentioned above in this application, surface treatment is proposed for surface finishing and protection. However, in the implementation process, the method and thickness parameters of the protection treatment may not be specifically defined, which may result in the inability to effectively prevent oxidation and corrosion, affecting the long-term service life and structural stability of the radiator.

[0086] In this regard, this application further proposes that in the preparation method of the above-mentioned graphene foam copper composite heat sink, the surface treatment in step 5 is at least one of mechanical grinding, mirror polishing, and spraying an anti-oxidation and anti-corrosion coating; the thickness of the anti-oxidation and anti-corrosion coating is 5 to 20 μm.

[0087] Specifically, the mechanical grinding in the surface treatment aims to remove residual slurry, burrs, oxide layers, and other potential defects from the dried and cured composite substrate surface, ensuring a smooth and clean surface and providing a good foundation for subsequent finishing and protective treatments. Mechanical grinding can be achieved in various ways, such as belt grinding, abrasive wheel grinding, vibratory grinding, or sandblasting. The mirror polishing further improves the surface smoothness of the composite radiator, reduces surface roughness, thereby reducing surface thermal resistance and improving the product's appearance. Mirror polishing can be achieved using mechanical polishing (such as using cloth wheels or wool wheels with polishing compound), electrochemical polishing, or chemical polishing. The spraying of the anti-oxidation and anti-corrosion coating forms a dense protective film on the surface of the composite radiator, effectively isolating it from contact with the external environment, thus preventing oxidation, corrosion, and other chemical erosion during long-term use and significantly extending the radiator's service life. The anti-oxidation and anti-corrosion coating can be applied using air spraying, high-pressure airless spraying, electrostatic spraying, or dip coating. The thickness of the antioxidant and anti-corrosion coating is 5–20 μm. This thickness range was carefully considered to ensure that the coating provides sufficient protection, forming a continuous and dense protective layer, without significantly increasing thermal resistance due to excessive thickness, thus affecting the overall thermal conductivity of the composite heat sink, while also effectively controlling material costs. The coating thickness can be controlled by precisely adjusting the parameters of the spraying equipment (such as spraying pressure, nozzle diameter, and travel speed), the viscosity of the coating, and the curing conditions.

[0088] This application's solution specifies the surface finishing step 5 of the above preparation method, making the surface treatment process of the composite heat sink more refined and efficient. First, mechanical grinding and / or mirror polishing thoroughly remove physical defects and residues from the composite substrate surface, providing an ideal adhesion interface for the subsequent protective coating and ensuring uniform and firm adhesion. Second, spraying an anti-oxidation and anti-corrosion coating, as a chemical protection method, effectively prevents oxidation and corrosion of the composite heat sink in harsh environments, thereby maintaining its long-term stable thermal conductivity and structural integrity. By precisely limiting the coating thickness to the range of 5–20 μm, this solution cleverly balances the relationship between protective effect and thermal conductivity, avoiding the problems of insufficient protection due to an excessively thin coating or increased thermal resistance due to an excessively thick coating. Therefore, this solution not only solves the potential protection deficiencies of traditional surface treatments but also significantly improves the reliability and service life of the composite heat sink through the organic combination of physical finishing and chemical protection, ensuring excellent heat dissipation performance during long-term operation.

[0089] The following is a specific example illustrating the process of preparing the graphene foam copper composite heat sink. During the initial surface finishing of the dried and cured composite substrate, mechanical grinding with P400–P800 abrasive belts can be used first to remove residual graphene nano-ceramic slurry curing layer and microburrs, achieving a surface roughness of Ra 0.8–1.6 μm. Subsequently, a polishing paste containing alumina or silica abrasives is used in conjunction with a high-speed rotating wool wheel for mirror polishing until a mirror-like finish is achieved, further reducing the surface roughness to Ra 0.1–0.2 μm. Finally, a polymer-based anti-oxidation and anti-corrosion coating is uniformly sprayed onto the surface of the composite heat sink using high-pressure airless spraying technology. By precisely controlling the spraying pressure, nozzle-workpiece distance, and spraying speed, the coating thickness is stably controlled between 10–15 μm, and then cured at a specified temperature.

[0090] The above technical solutions can effectively solve the problem of insufficient surface protection of composite radiators, significantly improve their oxidation and corrosion resistance, thereby ensuring the stability of thermal conductivity and structural integrity of composite radiators during long-term use, and greatly extending the service life of the products.

[0091] In some of the solutions described above in this application, a slurry is injected in a vacuum environment to wet the porous substrate. However, in this process, tiny air bubbles may remain after the slurry is injected or it may not fully penetrate the micropores of the substrate, resulting in incomplete filling and increased interfacial gaps. This leads to increased interfacial thermal resistance and the risk of coating peeling, affecting the overall thermal conductivity and structural stability of the composite heat sink.

[0092] In this regard, this application further proposes that after the slurry injection is completed in step 3, it should be maintained for 10 minutes. - Allow the slurry to stand in a vacuum environment for 5–15 minutes to ensure that the slurry fully penetrates the micropores of the matrix and eliminates air bubbles.

[0093] In this technical solution, 10 is maintained. - ¹Pa vacuum environment refers to the low-pressure state maintained inside the mold cavity after the graphene nano-ceramic slurry is injected into the porous matrix, with the pressure value precisely controlled at 10. - ¹Pa. Maintaining this vacuum environment aims to prevent external air from re-entering the mold cavity, while inhibiting the expansion or reformation of any microbubbles that may exist within the slurry, thus providing favorable conditions for further penetration of the slurry into the porous matrix and for bubble escape. This can be achieved by: continuously evacuating the cavity using a precision vacuum pump after slurry injection, coupled with real-time monitoring and feedback control using a vacuum sensor to ensure the cavity pressure remains stable at the target value; or, immediately after injection, closing all valves connected to the outside, utilizing the cavity's own sealing properties to maintain a vacuum state, supplemented by a vacuum buffer tank to stabilize the pressure; and allowing 5–15 minutes of settling refers to providing the slurry with a period of undisturbed time while maintaining a specific vacuum environment, allowing it to undergo sufficient physical processes within the microstructure of the porous matrix. The purpose of settling is to provide sufficient time for the slurry to complete capillary penetration and to allow any microbubbles that may exist in the slurry to slowly rise and escape from the slurry surface under low pressure.

[0094] Implementation methods may include: after the slurry injection is completed and the required vacuum level is reached, entering a static mode via a timer control system, during which any operations that may cause vibration or pressure fluctuations are stopped; or, placing the mold cavity on a vibration isolation platform to ensure that it is not disturbed by external mechanical vibration during the static period, thereby promoting stable slurry penetration and natural bubble removal. Ensuring sufficient slurry penetration into the matrix micropores aims to ensure that the graphene nano-ceramic slurry can completely wet all the micropores and channels inside the porous matrix, leaving no unfilled areas. Sufficient penetration is key to forming a dense composite structure, directly affecting the thermal conductivity and mechanical strength of the composite heat sink. Implementation methods may include: optimizing the rheological properties of the slurry, such as adjusting viscosity and surface tension, to give it good flowability and wettability under low pressure; or, during the static process, the slurry, driven by capillary forces, can overcome the resistance of the micropores and gradually fill all microstructures. Eliminating filling bubbles aims to completely remove bubbles that may be trapped or generated by the slurry during the filling process. The presence of air bubbles creates voids within composite materials. These voids not only hinder heat conduction and increase interfacial thermal resistance, but also weaken the overall structural integrity of the material. Solutions include: in a vacuum environment, the bubbles expand, increasing buoyancy and making them easier to separate from the slurry and float to the surface; or, utilizing the degassing properties of the slurry itself, combined with vacuum and settling time, allowing sufficient time for the microbubbles to coalesce and dissipate.

[0095] In the preparation of graphene foam copper composite heat sinks, the traditional method involves injecting graphene nano-ceramic slurry into the mold in step 3 to impregnate and fill the pores of the porous matrix. Although a vacuum of 1000 kJ / m³ is employed... - While a ¹Pa vacuum level is used, if the slurry is not further processed after injection, there may still be issues such as incomplete penetration of the slurry into the substrate micropores or residual micro-bubbles. These problems can lead to incomplete filling, increased interfacial gaps, and consequently, increased interfacial thermal resistance, coating peeling risk, and affect the overall thermal conductivity and structural stability of the composite heat sink. This application addresses this issue by maintaining a 10 Pa vacuum level after slurry injection. - The above-mentioned problems were effectively solved by creating a vacuum environment of ¹Pa and allowing it to stand for 5–15 minutes. Specifically, after the slurry was injected into the porous matrix, the cavity inside the mold was maintained at 10 Pa. -A ¹Pa vacuum environment provides continuous low-pressure conditions for further flow and penetration of the slurry within the porous matrix, effectively preventing the re-entry of external air and inhibiting the formation or expansion of any microbubbles that may exist within the slurry. Furthermore, allowing the slurry to stand for 5–15 minutes provides sufficient time for capillary penetration into the micropores of the porous matrix, enabling it to overcome the resistance of the micropores and penetrate deep into every tiny pore, thus achieving thorough wetting. Simultaneously, under the continuous vacuum environment, microbubbles trapped within the slurry or generated by the slurry expand in volume due to the reduced external pressure, increasing buoyancy and allowing sufficient time for them to slowly rise and escape from the slurry surface during the standing period, thus being effectively eliminated. Through these techniques, the filling of the slurry within the pores of the porous matrix becomes more continuous and dense, significantly reducing interfacial gaps and bubble defects. This results in a tight, pore-free bond between the graphene nano-ceramic slurry curing layer and the porous substrate, significantly reducing interfacial thermal resistance and ensuring efficient heat transfer from the porous substrate to the graphene nano-ceramic slurry curing layer. This optimized filling method not only improves the overall thermal conductivity of the composite heat sink but also strengthens the bond between the curing layer and the substrate, effectively preventing the risk of coating peeling and thus enhancing the structural stability and lifespan of the composite heat sink.

[0096] As a specific implementation method, in the process of preparing a graphene foam copper composite heat sink, after the graphene nano-ceramic slurry in step 3 is injected into the customized molding mold through the injection port and completely impregnates and fills the pores of the porous matrix, the injection system will stop supplying the slurry. At this time, the vacuum pump system inside the mold cavity will continue to work, and a high-precision vacuum sensor will monitor the internal pressure of the cavity in real time to ensure that it is stably maintained at 10. - A vacuum level of ¹Pa is maintained. While maintaining this vacuum environment, a timer is activated to allow the mold cavity, along with the internal porous matrix and slurry, to enter a settling state for 10 minutes. During this settling period, the slurry continuously permeates through the micropores within the porous matrix via capillary action. Simultaneously, any tiny air bubbles present in the slurry will gradually expand under low pressure and slowly rise to the slurry surface, eventually escaping. After the settling period, the vacuum pump system can be stopped, and the mold cavity can proceed with subsequent drying and curing processes.

[0097] By maintaining for 10 minutes after slurry injection. -By operating under a ¹Pa vacuum environment and allowing it to stand for 5–15 minutes, this application effectively solves the problem of residual micro-air bubbles or insufficient penetration into the micropores of the matrix after slurry injection. This allows the graphene nano-ceramic slurry to fully and densely fill all the pores of the porous matrix, significantly reducing interfacial gaps and internal voids, thereby greatly reducing interfacial thermal resistance. Ultimately, this not only ensures the stability and efficiency of the overall thermal conductivity of the composite heat sink, but also enhances the bonding strength between the cured graphene nano-ceramic slurry layer and the porous matrix, improving the structural integrity and long-term reliability of the composite heat sink.

[0098] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A graphene foam copper composite material heat sink, characterized in that, Using copper foam or aluminum foam as a porous matrix, the pores of the porous matrix are filled with a solidified graphene nano-ceramic slurry layer; the porosity of the porous matrix is ​​60%–90%, the overall density of the composite heat sink is 0.7–3.8 g / cm³, and the overall thermal conductivity of the composite heat sink is ≥1200 W / (m³). K).

2. The graphene foam copper composite material heat sink according to claim 1, characterized in that, The porous matrix is ​​copper foam, with a porosity of 75% to 90% and a pore size of 0.5 to 5 mm.

3. The graphene foam copper composite material heat sink according to claim 1, characterized in that, The porous matrix is ​​aluminum foam, the porosity of which is 60% to 85%, and the pore size of which is 1 to 8 mm.

4. The graphene foam copper composite material heat sink according to claim 1, characterized in that, The graphene nano-ceramic slurry curing layer is continuously and densely filled in the pores of the porous matrix, and there are no pores or interface gaps between the graphene nano-ceramic slurry curing layer and the porous matrix.

5. A graphene foam copper composite material heat sink according to claim 1, characterized in that, The overall structure of the composite radiator can be any one of the following: plate-shaped, column-shaped, fin-shaped, or honeycomb-shaped.

6. A graphene foam copper composite material heat sink according to claim 1, characterized in that, The graphene nano-ceramic slurry curing layer is made of graphene powder, nano-ceramic powder, organic binder, and deionized water; wherein the content of graphene powder is 3% to 10 wt% and the content of nano-ceramic powder is 15% to 25 wt%.

7. A method for preparing a graphene foam copper composite heat sink according to any one of claims 1 to 6, characterized in that, Includes the following steps: Step 1: Select a porous substrate of copper foam or aluminum foam with matching specifications, process it to the preset size and structural specifications through cutting and shaping processes, and remove burrs, oxide layer and impurities in the pores of the porous substrate surface. Step 2: Place the processed porous substrate flat into the customized molding mold, complete the positioning and fixation, and seal the mold cavity; Step 3: Evacuate the mold cavity to 10°C. - ¹Pa vacuum degree, after holding pressure for 3 to 10 minutes, uniformly inject graphene nano-ceramic slurry into the mold to completely wet and fill the pores of the porous matrix. Step 4: Place the porous matrix after injection molding, along with the molding die, into a drying device and dry and cure at a constant temperature to obtain a preliminary composite matrix; Step 5: Perform surface finishing and protective treatment on the dried and cured composite substrate to remove residual slurry and defects, and finally obtain the composite heat sink; Step 6: Test the thermal conductivity, density, and appearance accuracy of the processed composite heat sink. After passing the tests, remove dust and package it.

8. The method for preparing the graphene foam copper composite heat sink according to claim 7, characterized in that, In step 4, the drying and curing temperature is 50-150℃, the drying and curing time is 6-13h, and the drying process adopts a segmented heating mode with a heating rate of 2-5℃ / min.

9. The method for preparing the graphene foam copper composite heat sink according to claim 7, characterized in that, The surface treatment in step 5 is at least one of mechanical grinding, mirror polishing, and spraying an anti-oxidation and anti-corrosion coating; the thickness of the anti-oxidation and anti-corrosion coating is 5 to 20 μm.

10. The method for preparing the graphene foam copper composite heat sink according to claim 7, characterized in that, After the slurry injection in step 3 is completed, maintain for 10 minutes. - Place in a vacuum environment for 5–15 minutes.

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