High-performance metal polymer connecting structure and preparation method thereof

Abstract

The invention relates to the field of metal polymer connection, and discloses a high-performance metal polymer connection structure and a preparation method thereof.The connection structure is of a three-layer type, a metal substrate is made of high-strength copper alloy subjected to micro-arc oxidation treatment, and a ceramic film on the surface of the metal substrate has the characteristics of high hardness and the like; the porous metal middle layer is of a sintered copper-nickel alloy porous structure, and the pore diameter is in gradient distribution; and the polymer outer layer is polyether-ether-ketone (PEEK) added with carbon fibers. The preparation method comprises the following steps: ball-milling and mixing copper-nickel powder, adding a pore-forming agent, pressing into a blank, sintering to obtain the middle layer, carrying out hot-pressing combination on the middle layer and the substrate, injecting the molten polymer, and finally annealing. The innovative structure and process overcome the defects of a traditional connecting method, the bonding strength of the metal substrate and the middle layer is improved, the performance of the polymer outer layer is enhanced, the overall mechanical property is excellent, high temperature resistance, light weight, environment friendliness and cost reduction are achieved, and the method is suitable for high-temperature and light-weight components such as aviation heat exchangers.

Description

Technical Field

[0001] The present invention relates to the technical field of metal-polymer connection, and particularly to a high-performance metal-polymer connection structure and a preparation method thereof. Background Art

[0002] Heat exchangers play a crucial role in many industries such as aviation, aerospace, and automotive. With the continuous development of green and low-carbon technologies, the demand for lightweight heat exchangers is increasing day by day, and the research on metal-polymer composite heat exchangers has attracted much attention. In such composite heat exchangers, metals are responsible for heat transfer, and polymers provide structural support. The combination of the two can achieve efficient heat dissipation and weight reduction. However, when metals and polymers are connected, due to pressure and temperature fluctuations, stress concentration is likely to occur at the joints, resulting in defects such as fracture and connection failure.

[0003] Traditional methods for connecting polymers and metals include mechanical connection, bonding, and welding, etc., but all have certain problems. Mechanical connection relies on external components such as bolts and rivets, with uneven stress distribution, affecting reliability, sealing performance, and lightweight characteristics. Bonding uses adhesives and faces challenges such as sensitivity to load direction, reliability, durability, efficiency, and environmental impact. Welding technologies (such as laser welding and ultrasonic welding) can form connections, but the physical and chemical property differences between metals and polymers easily lead to stress concentration and fatigue, and welding often requires surface pretreatment and special equipment, increasing costs and complexity.

[0004] Emerging direct molding bonding technologies form microscopic mechanical interlocks by chemically etching the metal surface and then injecting molten polymer to enhance the connection strength. However, the chemical etching process has problems in control, stability, and cost, and it is difficult to etch low-reactivity metal alloys. The pores generated have insufficient interlock strength in the tensile direction and uneven vertical load transfer. Laser surface treatment can achieve micro-mechanical interlocks, but the pores generated have limited improvement in tensile bearing capacity. Selective laser melting (SLM) can improve the tensile strength, but the processing parameters affect the product quality, and this technology is complex, time-consuming, and costly, which is not conducive to large-scale production. Summary of the Invention

[0005] Aiming at the deficiencies of the existing technology, the present invention provides a high-performance metal-polymer connection structure and a preparation method thereof. Through innovative material combinations and process optimizations, many deficiencies of the existing connection methods are overcome, realizing high-strength, efficient, low-cost, lightweight, and environmentally friendly metal-polymer connections, and improving the application performance of metal-polymer composite structures in fields such as heat exchangers.

[0006] The technical methods adopted by the present invention to solve the above problems are as follows.

[0007] 1. Connection Structure Design

[0008] Design a three-layer metal-polymer connection component, including a metal substrate, a porous metal intermediate layer, and a polymer outer layer. The metal substrate is made of a high-strength copper alloy, and its surface is subjected to special micro-arc oxidation treatment to form a ceramic film. This ceramic film has high hardness, high wear resistance, and good corrosion resistance. At the same time, it increases the surface roughness of the metal substrate, which is beneficial to the bonding with the porous metal intermediate layer.

[0009] The porous metal intermediate layer is a sintered copper-nickel alloy porous structure. The selection of this alloy composition not only ensures the good formability of the porous structure but also improves its strength and corrosion resistance. The pore size distribution of the porous structure shows a gradient distribution, with smaller pore sizes on the side close to the metal substrate and larger pore sizes on the side close to the polymer outer layer, which is convenient for the filling and mechanical interlocking of the polymer.

[0010] The polymer outer layer uses polyetheretherketone (PEEK) with high temperature resistance and high strength. Carbon fiber reinforcing phase is added to the PEEK polymer to further improve its mechanical properties, and the carbon fibers are uniformly dispersed in the PEEK matrix.

[0011] 2. Preparation method

[0012] Preparation of the porous metal intermediate layer:

[0013] Weigh copper powder and nickel powder according to the ratio, put them into a planetary ball mill, add an appropriate amount of stearic acid (or ethanol) as a dispersant, and carry out ball milling to make the copper powder and nickel powder fully mixed and uniform.

[0014] Mix the mixed powder with a pore-forming agent (such as ammonium bicarbonate) in a certain ratio, and then press the mixture into a green body.

[0015] Put the green body into a vacuum sintering furnace, first pre-sinter under vacuum conditions to remove the gas generated by the decomposition of the pore-forming agent; then raise the temperature and sinter again to make the copper-nickel alloy powder fully sintered to form a porous structure. A segmented heating system is adopted during the sintering process to ensure uniform heating of the green body and reduce internal stress.

[0016] Forming of the connection structure:

[0017] Combine the prepared porous metal intermediate layer with the metal substrate through a hot pressing process. Before hot pressing, perform plasma treatment on the micro-arc oxidation surface of the metal substrate to clean the surface and improve its surface activity, so as to form a strong metallurgical bond between the porous metal intermediate layer and the metal substrate.

[0018] Heat the carbon fiber-reinforced PEEK polymer particles to the molten state, and then use an injection molding process to inject the molten polymer into the pores of the porous metal intermediate layer to ensure that the polymer fully fills the pores and forms a good mechanical interlock.

[0019] After injection molding, the connection structure is post-processed, including annealing to eliminate internal stress; it is then machined to achieve the required dimensional accuracy and surface finish.

[0020] The present invention provides a high-performance metal-polymer connection structure and a preparation method thereof, which has the following beneficial effects:

[0021] 1. The present invention adopts high-strength copper alloy as the metal substrate, and combines micro-arc oxidation and plasma treatment to significantly improve the bonding strength between the metal substrate and the porous metal intermediate layer. Compared with the traditional metal substrate treatment method, the bonding strength is improved.

[0022] 2. The present invention not only optimizes the pore structure and improves the controllability of porosity and pore size distribution through the design of a copper-nickel alloy porous intermediate layer, but also enhances the mechanical properties and corrosion resistance of the intermediate layer, so that it can better transfer stress when subjected to external loads, thereby improving the overall strength and stability of the connection structure. At the same time, the carbon fiber reinforced PEEK polymer outer layer improves its tensile strength and high temperature resistance while maintaining the lightweight advantage of the polymer, effectively expanding the application range of the connection structure.

[0023] 3. The present invention ensures the quality and performance consistency of the porous metal intermediate layer through the precisely controlled powder metallurgy process, including ball milling parameters, pressing pressure, sintering system, etc., and realizes the integrated molding of the metal-polymer connection structure by combining hot pressing with injection molding, avoiding the interface defects that may occur in traditional connection methods, and improving the reliability and sealing of the connection. At the same time, the optimized process parameters ensure the full filling of the polymer in the porous structure and good mechanical interlocking, so that the connection strength is further improved.

[0024] 4. The connection structure prepared by the present invention has excellent mechanical properties, and the tensile strength and shear strength are significantly improved compared with the existing technology, which can meet more stringent engineering application requirements. Good high temperature resistance, can still maintain stable performance under high temperature environment, suitable for heat exchangers and other equipment under high temperature working conditions. Lightweight design, through reasonable selection of materials and optimized structure, the overall weight of the connection structure is reduced compared with the traditional metal connection structure, which helps to improve the energy efficiency and operating performance of the equipment.

[0025] 5. The preparation process of the present invention is simpler than the prior art and uses common materials, which reduces production costs. Compared with high-end technologies such as selective laser melting, the cost is reduced, no harmful chemical etchants and adhesives are used, and the pollution to the environment is reduced, which meets environmental protection requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 is a sample preparation flow chart of the present invention;

[0027] Figure 2 This is the process flow chart of the sample preparation for the present invention;

[0028] Figure 3 This is the flow chart of the present invention;

[0029] Figure 4 This is the sample structure diagram of the present invention. Detailed implementation manners

[0030] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings of the present invention specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0031] Embodiment 1:

[0032] Please refer to the attached Figure 1 - attached Figure 4 , the embodiment of the present invention provides a preparation method for a high-performance metal-polymer connection structure, including the following steps:

[0033] 1. Material preparation

[0034] Select C17200 copper alloy as the metal substrate material, process it into a plate with a thickness of 8 mm, and then perform micro-arc oxidation treatment to form a ceramic film with a thickness of 30 μm.

[0035] Weigh copper powder and nickel powder (nickel content is 25%) with a particle size of 30 μm and ammonium bicarbonate pore-forming agent with a particle size of 100 μm at a mass ratio of 3:1, and prepare an appropriate amount of stearic acid as a dispersant.

[0036] Select PEEK polymer particles containing 3% carbon fiber (length is 20 μm) as the outer layer material.

[0037] 2. Preparation of the porous metal intermediate layer

[0038] Put the copper powder and nickel powder into a planetary ball mill, add stearic acid, and ball mill at a speed of 300 rpm for 3 hours.

[0039] Mix the ball-milled mixed powder with ammonium bicarbonate in a ratio of 10:1, and press it into a green body under a certain pressure.

[0040] Put the green body into a vacuum sintering furnace, first pre-sinter at a vacuum degree of 10 -2 Pa and an appropriate temperature for 1.5 hours, then raise the temperature to 1000 °C at a heating rate of 10 °C / min, and sinter for 3 hours to obtain the porous metal intermediate layer.

[0041] 3. Forming of the connection structure

[0042] After the micro-arc oxidation surface of the metal substrate is subjected to plasma treatment, it is hot-pressed with the porous metal intermediate layer at a certain temperature and pressure for 45 minutes.

[0043] The PEEK polymer particles are heated to 380 °C and melted, and injected into the pores of the porous metal intermediate layer at an injection pressure of 8 MPa and an injection speed of 30 cm 3 / s.

[0044] After injection molding, it is annealed at 200 °C for 3 hours, and then machined to the required size.

[0045] Beneficial effects of Example 1: In this Example 1, a C17200 copper alloy substrate is combined with a 3:1 copper-nickel porous intermediate layer. Through micro-arc oxidation and gradient pore design, the bonding strength between the metal / porous layer is increased by 60%, the porosity is 67%, and 3% carbon fiber PEEK is uniformly filled. After molding, the interfacial tensile strength reaches 58 MPa, with both lightweight (weight reduced by 55%) and high-temperature stability at 250 °C, suitable for conventional aviation heat exchangers, and prominent cost-effectiveness.

[0046] Example 2:

[0047] 1. Material preparation

[0048] The metal substrate uses C18150 copper alloy with a thickness of 6 mm, and the thickness of the ceramic film after micro-arc oxidation treatment is 20 μm.

[0049] The mass ratio of copper powder to nickel powder is 4:1 (nickel content is 20%), the particle sizes are 20 μm and 120 μm respectively, the particle size of the pore-forming agent is 90 μm, and the dispersant is the same as in Example 1.

[0050] The carbon fiber content in the PEEK polymer is 4% and the length is 30 μm.

[0051] 2. Preparation of the porous metal intermediate layer

[0052] The ball milling parameters are 400 rpm and 2.5 hours, and the ratio of the mixed powder to the pore-forming agent is 12:1, and it is pressed under a certain pressure.

[0053] The pre-sintering conditions are a vacuum degree of 10 -3 Pa, appropriate temperature, 1 hour, the sintering heating rate is 15 °C / min, and the sintering temperature is 1050 °C for 2.5 hours.

[0054] 3. Forming of the connection structure

[0055] Hot press for 40 minutes under certain temperature and pressure, injection molding temperature 370 °C, pressure 6 MPa, injection speed 20 cm 3 / s, annealing temperature 190 °C, 2.5 hours, and subsequent machining is the same as in Example 1.

[0056] Advantages of Example 2: In this Example 2, by optimizing the fineness of copper-nickel powder (20-μm Cu powder) and the sintering process, a gradient pore structure of 10-20 μm (filling rate 96%) is obtained. Combined with 4%-carbon fiber-reinforced PEEK low-temperature injection molding (370 °C, 6 MPa), the interfacial shear strength is increased to 62 MPa, and the performance only decreases by 3% after 1000 h of salt spray test, which is suitable for highly corrosive environments such as the ocean, and the comprehensive cost is reduced by 18%.

[0057] Example 3:

[0058] 1. Material preparation

[0059] Use C70250 copper alloy as the metal substrate with a thickness of 10 mm and a ceramic film thickness of 40 μm.

[0060] The mass ratio of copper-nickel powder is 2:1 (nickel content 30%), the particle sizes are 25 μm and 150 μm, the pore-forming agent particle size is 80 μm, and the dispersant remains unchanged.

[0061] The carbon fiber content of the PEEK polymer is 5% and the length is 40 μm.

[0062] 2. Preparation of the porous metal intermediate layer

[0063] Ball mill for 3.5 hours at a rotation speed of 200 rpm, mixing ratio 9:1, and press under a certain pressure.

[0064] Pre-sinter at an appropriate temperature, vacuum degree 10 -2 Pa, 2 hours, heating rate 5 °C / min, sinter at 1100 °C for 4 hours.

[0065] 3. Forming of the connection structure

[0066] Hot press at 600 °C, pressure 15 MPa, 30 minutes, injection molding temperature 390 °C, pressure 10 MPa, injection speed 50 cm 3 / s, anneal at 220 °C for 4 hours, and subsequent machining is the same as in Example 1.

[0067] Beneficial effects of Example 3: In this Example 3, a 30% high-nickel-content alloy and a 1100°C ultra-high-temperature sintering technology are used to achieve a shear strength of 75 MPa under a working condition of 300°C. Combined with 5% long carbon fiber PEEK high-pressure injection molding (10 MPa), the tensile strength reaches 68 MPa, the porosity homogeneity is increased by 20%, and there is no delamination under thermal shock (400°C short time), meeting the requirements of extreme scenarios in nuclear energy / space. The cost is reduced by 55% compared with the SLM process.

[0068] During the whole implementation process, the process parameters can be further optimized and adjusted according to actual needs to meet the requirements of different application scenarios. At the same time, continuously pay attention to the development of materials science and manufacturing technology, and constantly explore new material combinations and process improvement directions to further improve the performance and application scope of the metal-polymer connection structure. The protection scope of the present invention not only covers the technical solutions described in the specific embodiments, but also includes various deformations and improvements based on the technical ideas of the present invention. Any person skilled in the art within the technical scope disclosed by the present invention, any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention shall be covered within the protection scope of the present invention.

[0069] Comparative experiment:

[0070] I. Experimental design

[0071] (Experimental group)

[0072] Example 1: C17200 copper alloy substrate + 3:1 copper-nickel porous intermediate layer + 3% carbon fiber PEEK

[0073] Example 2: C18150 copper alloy substrate + 4:1 copper-nickel porous intermediate layer + 4% carbon fiber PEEK

[0074] Example 3: C70250 copper alloy substrate + 2:1 copper-nickel porous intermediate layer + 5% carbon fiber PEEK

[0075] (Control group)

[0076] Traditional chemical etching bonding: Aluminum alloy substrate + bonding with un-reinforced PEEK glue after chemical etching treatment (the thickness is the same as that of the example)

[0077] SLM process: 316L stainless steel substrate + laser melting to prepare a porous structure + pure PEEK filling

[0078] Test items

[0079] Mechanical properties: Tensile strength, shear strength, fatigue life

[0080] Environmental adaptability: Corrosion resistance (salt spray test), high-temperature stability (200 - 400°C)

[0081] Lightweight and Cost: Density Comparison, Single-piece Cost Calculation.

[0082] II. Experimental Procedures and Parameters

[0083] 1. Mechanical Property Testing

[0084] Equipment: Universal Material Testing Machine (ASTM D638 Standard)

[0085] Specimen Preparation: Prepare 5 standard tensile / shear specimens per group (size 50mm×10mm×2mm)

[0086] Testing Conditions:

[0087] Tensile Strength: Tensile rate 2mm / min, at room temperature (25°C) and high temperature (250°C) environments

[0088] Shear Strength: Double-lap specimens, loading rate 1mm / min

[0089] Fatigue Life: Load amplitude 40MPa, frequency 10Hz, number of cycles 10 6 times

[0090] 2. Corrosion Resistance Testing

[0091] Standard: GB / T 10125 Salt Spray Test (5% NaCl solution, 35°C, spraying)

[0092] Period: 1000 hours

[0093] Evaluation Indexes: Shear Strength Change Rate, Surface Corrosion Morphology (observed by SEM)

[0094] 3. High-temperature Stability Testing

[0095] Equipment: High-temperature Box Furnace (temperature controllable up to 500°C)

[0096] Testing Method: The specimens are kept at 250°C, 300°C, and 400°C for 2 hours, and the tensile strength is tested after cooling

[0097] 4. Cost Analysis

[0098] Process Cost: Material Cost, Equipment Energy Consumption, Labor Cost (calculated per piece)

[0099] Comparison Benchmark: Traditional Process (Chemical Etching), SLM Process (Powder + Laser Processing)

[0100] III. Experimental Results and Data Comparison

[0101] 1. Mechanical Properties

[0102]

[0103] 2. Environmental Adaptability

[0104]

[0105] 3. Lightweight and Cost

[0106] parameter Example 1 Example 2 Example 3 traditional process SLM process <![CDATA[Density (g / cm 3 )]]> 2.8 2.6 2.9 3.5 4.0

[0107] IV. Experimental Conclusions

[0108] Advantages in mechanical properties:

[0109] The tensile strength of the embodiment of the present invention is increased by 81% compared with the traditional chemical etching process (58 MPa in Example 1 vs 32 MPa), and the shear strength is increased by 66% compared with the SLM process (75 MPa in Example 3 vs 45 MPa).

[0110] The fatigue life is significantly better than the prior art (the attenuation rate in Example 3 is 1.9% vs 23% of the traditional one).

[0111] Breakthrough in environmental adaptability:

[0112] In the salt spray test, the performance retention rate of Example 2 is 97% (only 65% for the traditional process), and the micro-arc oxidation + gradient pore design effectively blocks the penetration of corrosive media.

[0113] In Example 3, there is no delamination under the thermal shock at 400 °C (30% delamination for the SLM process), and the high-nickel alloy and long carbon fiber cooperate to withstand extreme thermal loads.

[0114] Economic and lightweight benefits:

[0115] The cost of Example 1 is reduced by 40% compared with the traditional process, and the density is only 70% of the SLM process.

[0116] The comprehensive cost of Example 3 is reduced by 57% compared with the SLM process, and it is applicable to high-value-added fields such as aerospace.

[0117] V. Summary of Technical Applicability

[0118]

[0119] Conclusion: Through the gradient porous structure design and the collaborative optimization of materials and processes, the present invention solves the problems of low strength, poor temperature resistance, high cost, etc. in the traditional metal-polymer connection. The comprehensive performance fully exceeds the prior art and is applicable to diverse scenarios from conventional industries to aerospace.

[0120] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A high-performance metal-polymer connection structure, characterized in that: It comprises a metal substrate, a porous metal intermediate layer and a polymer outer layer, wherein: The metal substrate is a high-strength copper alloy, and the surface thereof has a ceramic film formed by micro-arc oxidation treatment; The porous metal intermediate layer is a sintered copper-nickel alloy porous structure, and the pore size distribution is gradient distribution, the pore size is smaller on the side close to the metal substrate, and the pore size is larger on the side close to the polymer outer layer; The polymer outer layer is polyetheretherketone (PEEK) containing a carbon fiber reinforcement phase, and the carbon fibers are uniformly dispersed in the PEEK matrix.

2. The method for preparing a high-performance metal-polymer connection structure according to claim 1, characterized in that: The following steps are involved: S1. Preparation of porous metal intermediate layer: Copper powder and nickel powder are weighed in proportion, put into a planetary ball mill, and a proper amount of stearic acid dispersant is added for ball milling; the mixed powder after ball milling is mixed with a pore-forming agent in a certain proportion, and pressed into a green body; the green body is put into a vacuum sintering furnace, first pre-sintered under vacuum conditions, and then sintered after heating, and the sintering process adopts a staged heating system; S2. Connection structure forming: After the micro-arc oxidation surface of the metal substrate is plasma treated, it is hot pressed with the porous metal interlayer; the carbon fiber reinforced PEEK polymer particles are heated to a molten state and injected into the pores of the porous metal interlayer; after injection molding, it is annealed and then machined to the required dimensional accuracy and surface finish.

3. The method for preparing a high-performance metal-polymer connection structure according to claim 2, characterized in that: In the step S1, the mass ratio of the copper powder to the nickel powder is 2:1-4:

1.

4. The method for preparing a high-performance metal-polymer connection structure according to claim 2, characterized in that: In the step S1, the pore-forming agent is ammonium bicarbonate.

5. The method for preparing a high-performance metal-polymer connection structure according to claim 2, characterized in that: In the step S1, the pore-forming agent may also be other compounds that can decompose to generate gas and form suitable pores.

6. The method for preparing a high-performance metal-polymer connection structure according to claim 2, characterized in that: In the step S2, the aluminum alloy of the metal substrate is C17200 copper alloy, C18150 copper alloy or C70250 copper alloy.

7. The method for preparing a high-performance metal-polymer connection structure according to claim 2, characterized in that: In the step S2, the plasma treatment may also use other plasma sources and parameter combinations that can clean the surface of the metal substrate and improve its activity.

8. The method for preparing a high-performance metal-polymer connection structure according to claim 2, characterized in that: In step S2, the injection molding process parameters can be adjusted within a certain range according to different equipment and material characteristics to ensure that the polymer fully fills the pores.

9. The method for preparing a high-performance metal-polymer connection structure according to claim 2, characterized in that: In step S2, the process sequence and parameters of the mechanical processing can be optimized and adjusted according to the final shape and precision requirements of the product.

10. The use of a high-performance metal-polymer connection structure according to claim 1, characterized in that: The connection structure is used in aviation heat exchangers, automotive engine cooling system components or other high-temperature, lightweight components that require metal-polymer connections.

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