Vacuum pressure-applying bonding method for high-thermal-conductivity material and complex curved surface structure

Abstract

The invention relates to the field of aerospace thermal control, in particular to a vacuum pressure bonding method for a high-thermal-conductivity material and a complex curved surface structure, which comprises the following steps: uniformly coating a bonding agent on a bonding surface of the high-thermal-conductivity material and the complex curved surface structure; compounding the bonding surface of the high-thermal-conductivity material on the bonding surface of the complex curved surface structure to form a composite body; using a vacuum bag to wrap the complex in a shape-following manner; a vacuum pump is started, the vacuum bag is vacuumized, the air pressure difference generated inside and outside the vacuum bag evenly acts on the bonding face of the high-heat-conduction material and the complex curved surface structure, and the high-heat-conduction material is tightly attached to the complex curved surface structure; and the pressure in the vacuum bag is kept stable, so that the adhesive is completely cured. Uniform pressure is provided for the bonding surface through the atmospheric pressure difference, it is ensured that the high-heat-conduction material is tightly combined with the complex curved surface structure, bubbles are prevented from being generated at the bonding position due to uneven pressure, and the bonding strength and the bonding quality are remarkably improved; meanwhile, the bonding time is effectively shortened, and the bonding efficiency is improved.

Description

Technical Field

[0001] The present invention belongs to the field of aerospace thermal control technology, and in particular relates to a vacuum pressure bonding method for a high thermal conductivity material and a complex curved surface structure. Background Art

[0002] In the thermal management of space optical remote sensors, carbon fiber composites are widely used due to their good mechanical properties, small thermal expansion coefficient and low density. However, the thermal conductivity of carbon fiber composites is low, and it is usually necessary to bond high thermal conductivity materials to the surface of the carbon fiber composites to improve the isothermal performance of the carbon fiber composites. The traditional bonding method is: first, apply an adhesive to the bonding surface of the high thermal conductivity material and the bonding surface of the carbon fiber composite; then, compound the bonding surface of the high thermal conductivity material with the bonding surface of the carbon fiber composite; finally, apply pressure to the high thermal conductivity material and the carbon fiber composite and maintain it for a certain period of time, and complete the bonding of the high thermal conductivity material after the adhesive is cured.

[0003] In this field, most of the methods used are to apply pressure to high thermal conductivity materials and carbon fiber composite materials by heavy objects such as flat plates and sandbags, or by bundling with polyimide tape. However, heavy object pressure or bundling pressure is only applicable to simple planar structures and is difficult to adapt to complex curved structures (such as load-bearing cylinders, antenna covers, and mirror frames of spacecraft). When applied to complex curved structures, traditional pressure bonding methods have the problem of uneven pressure and are prone to bubble formation. Therefore, traditional pressure bonding methods are difficult to provide sufficient and uniform pressure, resulting in a decrease in bonding strength and bonding effect, especially in the high-precision structures of spacecraft, where the bonding quality has a significant impact on thermal management efficiency. Summary of the invention

[0004] In view of this, the present invention aims to provide a vacuum pressure bonding method for high thermal conductivity materials and complex curved surface structures, so as to solve the problems of uneven pressure, easy formation of bubbles, long curing time, and thus affecting the bonding strength, bonding effect and bonding efficiency of traditional pressure bonding methods.

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows: A vacuum pressure bonding method for a high thermal conductivity material and a complex curved surface structure is implemented by using a vacuum pressure system, wherein the vacuum pressure system includes a vacuum bag, an air extraction valve, a vacuum valve, a connecting pipe and a vacuum pump, wherein the air extraction valve is installed on the vacuum bag and connected to the vacuum pump through a connecting pipe; A vacuum pressure bonding method for high thermal conductivity materials and complex curved surface structures includes the following steps: S1: Apply adhesive evenly on the bonding surface of high thermal conductivity materials and complex curved structures; S2: Compounding the bonding surface of the high thermal conductivity material onto the bonding surface of the complex curved structure to form a composite body; S3: Use a vacuum bag to wrap the composite body in a conformal manner, so that the bonding area of ​​the composite body is completely covered by the vacuum bag; S4: Start the vacuum pump to evacuate the vacuum bag. The pressure difference generated inside and outside the vacuum bag evenly acts on the bonding surface of the high thermal conductivity material and the bonding surface of the complex curved surface structure, so that the high thermal conductivity material is closely attached to the complex curved surface structure. S5: Keep the pressure in the vacuum bag stable to allow the adhesive to fully cure.

[0006] Furthermore, step S3 specifically includes the following steps: S31: unfolding the vacuum bag and placing the composite in the central area of ​​the vacuum bag; S32: Fold the edge of the vacuum bag so that the vacuum bag completely covers the composite body, and ensure that the edge of the vacuum bag fits tightly against the surface of the composite body; S33: Use tools or manually apply pressure to the vacuum bag to gradually exhaust the air in the vacuum bag so that the vacuum bag and the surface of the composite body fit tightly.

[0007] Furthermore, the vacuum pressure application system further includes a vacuum gauge, which is installed on the connecting pipe. The vacuum gauge monitors the vacuum degree in the vacuum bag to ensure that the vacuum degree reaches a predetermined value.

[0008] Furthermore, the predetermined value of the vacuum degree in the vacuum bag is 0.01Pa.

[0009] Furthermore, the vacuum pressure system also includes a vacuum valve, which is installed on the connecting pipe and is used to control the airflow in the connecting pipe.

[0010] Furthermore, before step S1, the following steps are also included: S0: Clean the bonding surface of complex curved structures and the bonding surface of high thermal conductivity materials.

[0011] Furthermore, the complex curved surface structure is composed of a material having a thermal conductivity lower than 10 W / m·K.

[0012] Furthermore, the high thermal conductivity material is a material having a thermal conductivity greater than 1000 W / m·K.

[0013] Compared with the prior art, the invention can achieve the following beneficial effects: The present invention adopts a vacuum pressure method to provide uniform pressure to the bonding surface through the atmospheric pressure difference, ensuring that the high thermal conductivity material is tightly combined with the complex curved surface structure, avoiding the generation of bubbles at the bonding point due to uneven pressure, significantly improving the bonding strength and quality, and effectively shortening the bonding time and improving the bonding efficiency. It is particularly suitable for bonding various complex curved surface structures. Compared with the traditional bundling or pressure method that uses a large amount of consumables, the present invention only requires a reusable vacuum pressure device, which reduces material waste and conforms to the concept of green manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments and descriptions of the present invention are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings: Figure 1 is a schematic structural diagram of a vacuum pressurizing system according to an embodiment of the present invention; Figure 2 It is a schematic flow chart of a vacuum pressure bonding method for a high thermal conductivity material and a complex curved surface structure according to an embodiment of the invention; Figure 3 It is a schematic diagram of the state after the composite body is wrapped by a vacuum bag according to an embodiment of the invention.

[0015] Description of the reference numerals: vacuum bag 1, exhaust valve 2, vacuum gauge 3, vacuum valve 4, connecting pipe 5, vacuum pump 6, composite body 7. DETAILED DESCRIPTION

[0016] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0017] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0018] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0019] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0020] The following will refer to Figure 1 and Figure 2 The invention is described in detail with reference to the embodiments.

[0021] The vacuum pressure bonding method for high thermal conductivity materials and complex curved surface structures provided in the embodiments of the present invention utilizes a vacuum pressure system to achieve bonding of high thermal conductivity materials to complex curved surface structures. High thermal conductivity materials are materials with a thermal conductivity coefficient of more than 1000W / m·K, such as graphene, carbon nanotubes and other materials; complex curved surface structures use materials with lower thermal conductivity (thermal conductivity coefficient less than 10W / m·K), such as carbon fiber composite materials, which are used to make general structural parts, such as satellite frames, rocket skins and other non-thermal protection components. The thermal conductivity of the adhesive should be above 2W / m·K to ensure that the overall thermal conductivity effect after bonding is not weakened.

[0022] like Figure 1As shown, the vacuum pressure system provided by the embodiment of the invention includes a vacuum bag 1, an exhaust valve 2, a vacuum gauge 3, a vacuum valve 4, a connecting pipe 5 and a vacuum pump 6. The vacuum bag 1 is used to wrap a composite body 7 composed of a high thermal conductivity material and a complex curved surface structure, and is used to form a closed space so that the bonding area of ​​the composite body 7 can be stressed under a vacuum state; the exhaust valve 2 is installed on the vacuum bag 1 and connected to the vacuum pump 6 through the connecting pipe 5, and is used to evacuate the vacuum bag 1; the vacuum gauge 3 is installed on the connecting pipe 5, and is used to monitor the air pressure in the vacuum bag 1 in real time to ensure that the required vacuum degree is maintained during the bonding process; the vacuum valve 4 is installed on the connecting pipe 5, and is used to control the size of the air flow in the connecting pipe 5 and the opening and closing of the connecting pipe 5, so as to facilitate the operator to control the vacuum state in the vacuum bag 1; the connecting pipe 5 is used to connect the vacuum pump 6 and the exhaust valve 2 to form a vacuum channel; the vacuum pump 6 is used to extract the air in the vacuum bag 1, so that a vacuum state is generated in the vacuum bag 1, thereby using the atmospheric pressure difference to apply uniform pressure to the bonding area of ​​the composite body 7, effectively avoiding the generation of bubbles in the bonding area, thereby improving the bonding strength and bonding quality.

[0023] The power of the vacuum pump 6 can be between 200W and 500W to ensure that the air in the vacuum bag 1 is exhausted in a short time to reach the specified vacuum pressure range (0.1atm~1atm). The bonding surface of the high thermal conductivity material and the bonding surface of the complex curved surface structure are subjected to uniform pressure applied from the outside, thereby improving the bonding quality and bonding effect. Of course, the present invention can also use vacuum pumps 6 of different types and powers according to actual needs to improve the vacuuming efficiency and bonding quality.

[0024] like Figure 2 As shown, the vacuum pressure bonding method of the high thermal conductivity material and the complex curved surface structure provided by the present invention includes the following steps: S0: Clean the bonding surface of complex curved structures and the bonding surface of high thermal conductivity materials.

[0025] The purpose of cleaning is to ensure that the bonding surface of the complex curved surface structure and the bonding surface of the high thermal conductivity material are clean, free of grease and dust. If the bonding surface of the complex curved surface structure and the bonding surface of the high thermal conductivity material are contaminated, the bonding effect will be seriously affected.

[0026] This step is an optional step. If the bonding surface of the complex curved structure and the bonding surface of the high thermal conductivity material can reach the cleanliness required for bonding, this step can be omitted.

[0027] S1: Apply adhesive evenly on the bonding surface of high thermal conductivity materials and complex curved structures.

[0028] Adhesives should be compatible with high thermal conductivity materials and complex curved surface structures to ensure bonding effect. The coating thickness of the adhesive should be moderate. Too thick or too thin will affect the final bonding strength.

[0029] S2: Compounding the bonding surface of the high thermal conductivity material onto the bonding surface of the complex curved surface structure to form a composite body 7.

[0030] During the composite process, ensure that the bonding surface of the high thermal conductivity material is aligned with the bonding surface of the complex curved structure. The alignment process needs to be carefully performed to avoid any bonding defects that may be caused by any misalignment, and try to avoid the generation of bubbles during the composite process.

[0031] S3: Use the vacuum bag 1 to wrap the composite body 7 in a conformal manner, so that the bonding area of ​​the composite body 7 is completely covered by the vacuum bag 1 .

[0032] The specific process of using the vacuum bag 1 to wrap the composite body 7 is as follows: S31 : unfold the vacuum bag 1 , and place the composite body 7 in the central area of ​​the vacuum bag 1 .

[0033] S32: Fold the edge of the vacuum bag 1 so that the vacuum bag 1 completely covers the composite body 7 , and ensure that the edge of the vacuum bag 1 is in close contact with the surface of the composite body 7 .

[0034] S33: Use a pressing tool such as a pressure roller or manually apply pressure to the vacuum bag 1 to gradually exhaust the air in the vacuum bag 1 so that the vacuum bag 1 and the surface of the composite 7 fit closely and reduce the space where air is trapped as much as possible.

[0035] After completing steps S31 to S33, check whether the vacuum bag 1 has wrinkles or is loose, and ensure that there are no obvious gaps in the entire bonding area, so as to achieve the best vacuuming effect.

[0036] The state of the composite body 7 after being wrapped in the vacuum bag 1 is as follows Figure 3 As shown, the purpose of the present invention to wrap the composite body 7 in a conformable manner is to exhaust the air in the vacuum bag 1 to the maximum extent before vacuuming, so that after the vacuum bag 1 is subsequently vacuumed, there will be no wrinkles or looseness, and the vacuum bag 1 and the surface of the composite body 7 will fit tightly.

[0037] S4: Start the vacuum pump 6 to evacuate the vacuum bag 1. The pressure difference generated inside and outside the vacuum bag 1 evenly acts on the bonding surface of the high thermal conductivity material and the bonding surface of the complex curved surface structure, so that the high thermal conductivity material is closely attached to the complex curved surface structure.

[0038] After starting the vacuum pump 6, the air in the vacuum bag 1 begins to be pumped out. As the air is pumped out, the pressure difference generated inside and outside the vacuum bag 1 causes the high thermal conductivity material to fit tightly on the complex curved surface structure. The vacuum degree in the vacuum bag 1 is monitored by the vacuum gauge 3 to ensure that the vacuum degree reaches 0.01 Pa. At this time, the external atmospheric pressure will evenly act on the bonding surface of the high thermal conductivity material and the complex curved surface structure, so that the bonding surface of the high thermal conductivity material and the complex curved surface structure is evenly stressed, avoiding the generation of bubbles.

[0039] The vacuum pressure method can provide 1×10 5 N / m 2 The pressure is more than 100 times that provided by sandbags and bundling pressure, and the pressure can be evenly applied to the bonding surface of the high thermal conductivity material and the complex curved surface structure. Compared with the sandbag and bundling pressure methods, the present invention provides a larger and uniform pressure through the vacuum pressure system, effectively eliminating the bubbles generated in the bonding area during the bonding process, ensuring that the high thermal conductivity material can be tightly combined with the complex curved surface structure, and improving the bonding strength and bonding effect. Due to the high efficiency of the vacuum pressure system, the entire bonding process time is also effectively shortened, greatly improving the bonding efficiency.

[0040] S5: Keep the pressure in the vacuum bag 1 stable to allow the adhesive to completely cure.

[0041] The vacuum bag 1 is kept in a vacuum state, waiting for the adhesive to completely cure. During this period, the pressure in the vacuum bag 1 must be stable to maintain a uniform bonding pressure. The curing time can be adjusted according to the type of adhesive used and the ambient temperature.

[0042] After the adhesive is cured, the vacuum state of the vacuum bag 1 is released, and the composite body 7 is carefully taken out. The bonding quality is checked to ensure that there are no bubbles on the bonding surface and the bonding strength meets the requirements.

[0043] The present invention significantly reduces the thermal resistance of the bonding interface through the vacuum pressure bonding method. In order to verify this technical effect, a standard thermal conductivity test method is used to compare the thermal resistance of the bonding interface using the vacuum pressure bonding method and the traditional bonding method.

[0044] Experimental methods: Thermal conductivity test: The test is carried out using the heat flow meter method (GB / T10295), which is a standard thermal conductivity test method. The thermal resistance is calculated by measuring the change in heat flow under different bonding methods.

[0045] Test sample: The test sample is a composite composed of a high thermal conductivity material (such as graphene) and a low thermal conductivity material (such as a carbon fiber composite material) 7. The test uses a conventional pressure bonding method and a vacuum pressure bonding method of the present invention.

[0046] Experimental results: When using the traditional pressure bonding method, the thermal resistance of the bonding interface is 0.45K·m² / W.

[0047] When the vacuum pressure application method of the present invention is used, the thermal resistance of the bonding interface is reduced to 0.35K·m² / W.

[0048] Data Analysis: It can be seen from the experimental data that the interface thermal resistance of the bonding method of the present invention is reduced by about 22%. The experimental data show that the vacuum pressure bonding method of the present invention effectively reduces the thermal resistance of the bonding interface, improves the thermal conductivity, and can better support efficient heat transfer between high thermal conductivity materials and low thermal conductivity structures.

[0049] The present invention significantly improves the bonding strength through the vacuum pressure bonding method. In order to verify this technical effect, standard tensile test and shear test methods are used to compare the bonding strength of the method of the present invention and the traditional bonding method under the same conditions.

[0050] Test sample: The test sample is composed of a high thermal conductivity material (graphene film) and a low thermal conductivity material (carbon fiber composite material of brand T700), and the bonding interface is bonded by a conventional pressure bonding method and the vacuum pressure bonding method of the present invention.

[0051] Experimental methods: Tensile test: According to GB / T33501-2017 carbon / carbon composite material tensile performance test method, a standard tensile testing machine is used to test the bonding strength. This method is widely used in tensile strength testing of bonding materials. It evaluates the strength of bonding materials by applying gradually increasing tensile force until the bonding interface breaks.

[0052] Shear test: According to GB / T28889-2012 composite material in-plane shear performance test method, a shear tester is used to measure the maximum shear strength of samples under different bonding methods. This method is suitable for evaluating the bonding strength of material interfaces under shear load.

[0053] Experimental results:

[0054] Summary of technical effects: According to the above experimental data, the vacuum pressure bonding method of the present invention shows significant improvement in improving bonding strength. Compared with the traditional pressure bonding method, the tensile strength is increased by about 25% and the shear strength is increased by about 27%. This technical effect proves that the present invention has higher bonding reliability in the bonding process of high thermal conductivity materials and low thermal conductivity structures, especially in high-precision aerospace equipment and other high-demand applications, and can provide more stable and lasting bonding performance.

[0055] The vacuum pumping system quickly establishes a stable air pressure difference, and the bonding time is reduced by about 40% compared with the traditional pressure bonding method. For example, the traditional pressure bonding method requires at least 6 hours of curing time, while the vacuum pressure bonding method of the present invention can be completed within 3.5 hours, greatly improving the bonding efficiency.

[0056] Compared with traditional pressure bonding methods, the vacuum pressure bonding method of the present invention has stronger adaptability, especially for complex curved surface structures in spacecraft (such as spherical antenna covers or irregular heat sinks). The vacuum pressure bonding method of the present invention can be effectively adapted without the need for additional design of molds or auxiliary tools, thereby significantly reducing production costs.

[0057] It should be understood that the various forms of processes shown above can be used to reorder, add or delete steps. For example, the steps described in the disclosure of the present invention can be performed in parallel, sequentially or in different orders, as long as the desired results of the technical solution disclosed in the present invention can be achieved, and this document does not limit this.

[0058] The above specific implementations do not constitute a limitation on the protection scope of the present invention. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations and substitutions can be made according to design requirements and other factors. Any modification, equivalent substitution and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A vacuum pressure bonding method for a high thermal conductivity material and a complex curved surface structure, characterized in that: It is realized by using a vacuum pressure system, which includes a vacuum bag, an air extraction valve, a connecting pipe and a vacuum pump. The air extraction valve is installed on the vacuum bag and connected to the vacuum pump through a connecting pipe. A vacuum pressure bonding method for high thermal conductivity materials and complex curved surface structures includes the following steps: S1: Apply adhesive evenly on the bonding surface of high thermal conductivity materials and complex curved structures; S2: Compounding the bonding surface of the high thermal conductivity material onto the bonding surface of the complex curved structure to form a composite body; S3: Use a vacuum bag to wrap the composite body in a conformal manner, so that the bonding area of ​​the composite body is completely covered by the vacuum bag; S4: Start the vacuum pump to evacuate the vacuum bag. The pressure difference generated inside and outside the vacuum bag evenly acts on the bonding surface of the high thermal conductivity material and the bonding surface of the complex curved surface structure, so that the high thermal conductivity material is closely attached to the complex curved surface structure. S5: Keep the pressure in the vacuum bag stable to allow the adhesive to fully cure.

2. The vacuum pressure bonding method for high thermal conductivity materials and complex curved surface structures according to claim 1, characterized in that: Step S3 specifically includes the following steps: S31: unfolding the vacuum bag and placing the composite in the central area of ​​the vacuum bag; S32: Fold the edge of the vacuum bag so that the vacuum bag completely covers the composite body, and ensure that the edge of the vacuum bag fits tightly against the surface of the composite body; S33: Use tools or manually apply pressure to the vacuum bag to gradually exhaust the air in the vacuum bag so that the vacuum bag and the surface of the composite body fit tightly.

3. The vacuum pressure bonding method for high thermal conductivity materials and complex curved surface structures according to claim 1, characterized in that: The vacuum pressure application system further includes a vacuum gauge, which is installed on the connecting pipe. The vacuum degree in the vacuum bag is monitored by the vacuum gauge to ensure that the vacuum degree reaches a predetermined value.

4. The vacuum pressure bonding method for high thermal conductivity materials and complex curved surface structures according to claim 3, characterized in that: The preset value of the vacuum degree in the vacuum bag is 0.01Pa.

5. The vacuum pressure bonding method for high thermal conductivity materials and complex curved surface structures according to claim 1, characterized in that: The vacuum pressure application system also includes a vacuum valve, which is installed on the connecting pipeline and is used to control the air flow size in the connecting pipeline.

6. The vacuum pressure bonding method for high thermal conductivity materials and complex curved surface structures according to claim 1, characterized in that: Before step S1, the method further includes the following steps: S0: Clean the bonding surface of complex curved structures and the bonding surface of high thermal conductivity materials.

7. The vacuum pressure bonding method for a high thermal conductivity material and a complex curved surface structure according to any one of claims 1 to 6, characterized in that: The complex curved surface structure is made of materials with a thermal conductivity lower than 10W / m·K.

8. The vacuum pressure bonding method for a high thermal conductivity material and a complex curved surface structure according to any one of claims 1 to 6, characterized in that: High thermal conductivity materials are materials with a thermal conductivity greater than 1000 W / m·K.

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