Contact protection layer of conductive terminal and preparation method thereof

Abstract

The invention relates to the technical field of conductive materials, and discloses a contact protection layer of a conductive terminal and a preparation method of the contact protection layer, the protection layer is composed of a dynamic self-repairing conductive layer, a nanofiber reinforced slow release layer and a high-thermal-conductivity wear-resistant layer, and comprehensive improvement of crack self-repairing, corrosion resistance, thermal conductivity and wear resistance is achieved through collaborative design of a multi-layer structure. The dynamic self-repairing conductive layer contains phosphorus-doped polypyrrole and dynamic repairing particles, cracks are repaired through electrochemical deposition, and a conductive network is recovered; the nanofiber reinforced slow-release layer is combined with TiO2 nanofiber and a corrosion inhibitor to provide crack inhibition and corrosion protection functions; according to the high-heat-conductivity wear-resistant layer, graphene and hexagonal boron nitride form a heat conduction network, the heat management performance is optimized, and the mechanical strength is improved. The protection layer effectively solves the problem of performance degradation caused by crack propagation and mechanical damage of a contact protection layer in the prior art, and the long-term stability, wear resistance and corrosion resistance of the contact protection layer are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of conductive materials, in particular to a contact protection layer of a conductive terminal and a preparation method thereof. Background Art

[0002] In modern electronic devices, conductive terminals are widely used in circuit board connectors, electronic device contact points, and automotive electrical interfaces. Their main function is to achieve reliable electrical signal transmission and energy distribution. With the improvement of the performance requirements of electronic equipment, the stability and durability requirements of conductive terminal contacts are increasing, especially under high-frequency mechanical contact, complex environment (such as high humidity, high salt spray) and high power current conditions. Its performance directly affects the overall reliability and service life of the equipment.

[0003] In the prior art, the contact protection layer of the conductive terminal usually adopts a single functional coating or a metal plating (such as gold plating, silver plating or alloy coating) to improve the conductivity and corrosion resistance. In addition, there are also studies that attempt to improve the corrosion resistance and wear resistance of the contacts by adding anti-corrosion coatings, wear-resistant coatings, etc. However, these methods still have great limitations. For example, the metal plating is easily worn due to friction or oxidation after long-term use, resulting in increased resistance and unstable signal transmission; at the same time, the single functional coating lacks targeted protection in complex environments and is prone to failure due to cracks or corrosion. In addition, the existing technology has insufficient thermal management capabilities in high-power current environments, and is prone to excessive temperature rise, further reducing the stability of the protective layer.

[0004] The main problem with the existing technology is that the contact protection layer is prone to performance degradation due to mechanical damage (such as cracks) during long-term use, and lacks an effective repair mechanism, making it difficult to maintain stable conductive performance. The degradation caused by such cracks not only affects the reliability of the conductive terminal, but also greatly shortens its service life and increases the cost of equipment maintenance and replacement. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a contact protection layer for a conductive terminal and a preparation method thereof, which solves the problem that the contact protection layer of the conductive terminal suffers from performance degradation and lacks self-repairing ability due to mechanical damage during long-term use.

[0006] To achieve the above object, the present invention is implemented by the following technical solution: a contact protection layer of a conductive terminal, the protection layer comprising the following layered structure: Surface layer: contains phosphorus-doped polypyrrole matrix, dynamic repair particles and superhydrophobic nanoparticles; Middle layer: contains nanofibers, microcapsule corrosion inhibitors, graphene sheets and polysiloxane matrix; Bottom layer: contains hexagonal boron nitride particles and polyimide matrix.

[0007] Preferably, the mass fraction of the phosphorus-doped polypyrrole matrix is ​​60%-80%, the mass fraction of the dynamic repair particles is 5%-10%, and the mass fraction of the superhydrophobic nanoparticles is 2%-5%.

[0008] Preferably, the dynamic repair particles are Ag + or Zn 2+ The super hydrophobic nanoparticles are surface-modified silica particles with a particle size range of 50-200 nm.

[0009] Preferably, the nanofibers in the intermediate layer are titanium titanate nanofibers with a diameter of 10-20 nm, and the microcapsule corrosion inhibitor is a microcapsule encapsulating an imidazole compound or vitamin E with a mass fraction of 2%-5%.

[0010] Preferably, the graphene sheet is multilayer graphene with a thickness of 0.34 nm and a mass fraction of 2%-5%; the mass fraction of the polysiloxane matrix is ​​70%-80%.

[0011] Preferably, the particle size of the hexagonal boron nitride particles in the bottom layer is 1-2 μm, and the mass fraction is 10%-20%; the mass fraction of the polyimide matrix is ​​80%-90%.

[0012] A method for preparing a contact protection layer of a conductive terminal comprises the following steps: (1) preparing a surface layer: mixing phosphorus-doped polypyrrole, dynamic repair particles, super-hydrophobic nanoparticles and photosensitive active molecules, coating, and curing including ultraviolet light curing and thermal curing; (2) preparing the intermediate layer: mixing the nanofibers with the microcapsule corrosion inhibitor, the graphene sheet and the polysiloxane matrix, coating them, and curing them at room temperature; (3) Preparation of the bottom layer: Hexagonal boron nitride particles are mixed with a polyimide matrix, coated and formed by high-pressure hot pressing.

[0013] Preferably, the coating process of the surface layer is a spin coating process, the spin coating speed is 1000-3000rpm, the time is 10-30 seconds; the light intensity of UV curing is 500-700mW / cm 2 , the thermal curing temperature is 120-150℃, and the time is 1-2 hours.

[0014] Preferably, the nanofibers of the intermediate layer are prepared by electrospinning, the electrospinning voltage is 15-20 kV, the flow rate is 0.5-1.0 mL / h, the spinning collection distance is 10-15 cm; the calcination temperature is 400-500° C., and the calcination time is 2-3 hours.

[0015] Preferably, the hexagonal boron nitride particles of the bottom layer and the polyimide matrix are mixed by high-pressure homogenization technology, and the homogenization pressure is 30-50 MPa; the temperature of hot pressing molding is 180-200° C., the pressure is 5-10 MPa, and the time is 1-2 hours.

[0016] The present invention provides a contact protection layer of a conductive terminal and a preparation method thereof. The present invention has the following beneficial effects: 1. The present invention adopts a layered composite structure design of a dynamic self-repairing conductive layer, a nanofiber-reinforced slow-release layer, and a high thermal conductivity wear-resistant layer, achieving the synergistic optimization effect of crack self-repair, corrosion resistance, wear resistance, and high thermal conductivity. Compared with the technical solution of a single functional material in the prior art, it solves the problem that it cannot take into account both self-repairing ability and long-term environmental stability.

[0017] 2. The present invention adopts Ag + or Zn 2+ The dynamic repair particle technology completes crack repair through electrochemical deposition mechanism, achieving the technical effect of quickly filling cracks and restoring conductivity. Compared with the existing technology that relies on external mechanical coating repair or thermal response repair, it solves the shortcomings of complex repair process, long time consumption and incomplete conductivity recovery in the crack area.

[0018] 3. The present invention adopts the technical solution of microcapsule corrosion inhibitor and nanofiber composite design, which achieves the technical effect of slow release of antioxidants and continuous inhibition of metal oxidation in a corrosive medium environment. Compared with the technical solution of directly doping antioxidants or using a single protective coating in the prior art, it solves the problem of uneven release of antioxidants and long-term failure of protective coatings.

[0019] 4. The present invention adopts a bottom layer design technology solution of hexagonal boron nitride and polyimide matrix composite, achieving the technical effect of combining high thermal conductivity with wear resistance. Compared with the conductive protective layer technology solution lacking efficient heat dissipation structure in the prior art, it solves the problem of material heat accumulation leading to performance degradation and contact failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the specification of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] Please refer to the attached Figure 1, an embodiment of the present invention provides a contact protection layer of a conductive terminal and a preparation method thereof, comprising: 1. Surface preparation (dynamic self-healing conductive layer) 1.1 Raw material preparation: The pyrrole monomer was dissolved in N,N-dimethylformamide (DMF), and phosphate (dopant, 3% by mass) was added, and stirred evenly at 25°C for 1 hour. Subsequently, 5% (mass fraction) of dynamic repair particles (AgCl-PEG complex) and 3% of superhydrophobic nano-silica particles (particle size 50-100 nm) were added, and ultrasonic dispersion was performed for 20 minutes (ultrasonic power 120W).

[0023] 1.2 Coating and curing: The prepared solution is applied to the surface of the conductive terminal by spin coating at a speed of 2000 rpm for 15 seconds to form a uniform coating. Next, a dual curing process is performed: UV curing: UV intensity 600mW / cm 2 , time 20 minutes; Thermal curing: temperature 130°C, time 1.5 hours.

[0024] 2. Preparation of intermediate layer (nanofiber reinforced sustained-release layer) 2.1 Nanofiber preparation: Tetrabutyl titanate (10 wt%) was dissolved in ethanol to prepare a precursor solution; a fiber membrane was formed by an electrospinning process (voltage 18 kV, flow rate 0.8 mL / h, collection distance 12 cm). The fiber membrane was calcined at 450°C for 2 hours to obtain TiO2 nanofibers with a diameter of 10-20 nm.

[0025] 2.2 Functional layer assembly: 10% TiO2 nanofibers and 5% microcapsule corrosion inhibitor (encapsulated vitamin E) were mixed, dispersed in 80% polysiloxane solution, and evenly spin-coated on the surface at a spin-coating speed of 1500 rpm and a coating thickness of 8-10 μm. Cured at room temperature for 24 hours.

[0026] 3. Bottom layer preparation (high thermal conductivity and wear-resistant layer) 15% hexagonal boron nitride (h-BN) particles were mixed with 85% polyimide (PI) solution, stirred at 45°C for 2 hours, and evenly dispersed by high-pressure homogenization equipment (pressure 40MPa). After coating under the middle layer, it was formed by hot pressing process (temperature 190°C, pressure 7MPa, time 2 hours) to form a bottom layer with a thickness of about 15μm.

[0027] Effect verification: Salt spray test: In 3.5% NaCl solution, there is no obvious corrosion spot after 500 hours of testing, and the contact resistance increases by <1%.

[0028] Friction test: 10N load, 20,000 frictions, contact resistance change <3%.

[0029] Repair test: needle scratch crack with a depth of 10μm, repair time <5 minutes, repair rate >95%.

[0030] Example 2: Preparation of a conductive terminal contact protective layer with enhanced corrosion resistance Surface adjustment: Based on the surface preparation of Example 1, Zn 2+ Composite (mass fraction 6%) replaces Ag + , further enhancing the dynamic repair capability in corrosive environments.

[0031] The coating and curing conditions remain unchanged.

[0032] Middle layer optimization: The microcapsule corrosion inhibitor uses imidazole compounds (3% by mass) to replace vitamin E to improve the corrosion resistance in an alkaline environment.

[0033] The electrospinning conditions were adjusted to a voltage of 20 kV, a calcination temperature of 500 °C, and a calcination time of 3 h to further improve the mechanical strength of the fiber.

[0034] Effect verification: Corrosion resistance: The salt spray test was extended to 1000 hours, and there were no obvious corrosion spots on the surface of the protective layer, and the contact resistance increased by <2%.

[0035] Example 3: Preparation of a conductive terminal contact protection layer to improve thermal conductivity Bottom layer enhanced design: In the preparation of the bottom layer, 3% (mass fraction) graphene sheets are added to construct a thermal conductive network together with h-BN.

[0036] The homogenization conditions were adjusted to a pressure of 50 MPa and a mixing time of 15 min, so that the graphene and h-BN were evenly distributed in the PI matrix.

[0037] Effect verification: Thermal conductivity test: The thermal conductivity coefficient is increased to 1.5 W / m·K (50% higher than that of Example 1), which effectively slows down the material degradation caused by electric current.

[0038] Example 4: Preparation of high humidity environment protection layer Surface Improvements: In the preparation of the surface layer, the amount of superhydrophobic nanoparticles added was increased to 5% (mass fraction) to improve the waterproof performance.

[0039] The photosensitizing active molecule is replaced with tetraphenylporphyrin (mass fraction 2%), and the density of the surface layer is further enhanced through photosensitive polymerization.

[0040] Effect verification: High humidity environment test: After exposure to 95% humidity and 35°C for 1000 hours, the contact resistance of the protective layer changes by <1%.

[0041] Example 5: Preparation of protective layer with optimized comprehensive performance Full-layer optimization: The surface layer, the sustained-release layer and the bottom layer are respectively combined by the optimization design methods of Example 2, Example 3 and Example 4 to form a multi-layer protective layer with optimized comprehensive performance.

[0042] Effect verification: Salt spray test: 1000 hours without corrosion; Friction test: 30,000 times contact resistance change <5%; High temperature test: At 85℃, the conductivity remains stable and the resistance change is <3%.

[0043] Comparative Example 1: Protective layer without dynamic repair particles Experimental process: Surface preparation: The surface layer is made of phosphorus-doped polypyrrole (80% by mass) and super-hydrophobic nanoparticles (5% by mass), but no dynamic repair particles such as Ag are added. + or Zn 2+ .

[0044] The solution was prepared in accordance with the solvent and process of Example 1 (DMF solvent, stirring for 1 hour, ultrasonic dispersion for 20 minutes).

[0045] Spin coating process: 2000 rpm, time 15 seconds; UV curing and thermal curing conditions are the same as in Example 1.

[0046] Preparation of middle and bottom layers: The materials and preparation process of the middle layer and the bottom layer are exactly the same as those in Example 1.

[0047] Comparative Example 2: Surface layer without phosphate doping Experimental process: Surface preparation: The surface layer uses polypyrrole without phosphate doping as the matrix material (mass fraction 80%), and the remaining components include dynamic repair particles (mass fraction 5%) and superhydrophobic nanoparticles (mass fraction 5%).

[0048] The spin coating process, UV curing and thermal curing conditions are consistent with those in Example 1.

[0049] Preparation of middle and bottom layers: The materials and preparation process of the middle layer and the bottom layer are exactly the same as those in Example 1.

[0050] Comparative Example 3: The middle layer does not contain a corrosion inhibitor Experimental process: Surface and bottom layer preparation: The surface layer and bottom layer materials and preparation processes are consistent with those in Example 1.

[0051] Middle layer preparation: The middle layer is composed only of TiO2 nanofibers (mass fraction 10%) and polysiloxane (mass fraction 90%), and no microcapsule corrosion inhibitor is added.

[0052] The nanofiber preparation, mixing, spin coating and curing processes are consistent with Example 1.

[0053] Comparative Example 4: The bottom layer does not contain graphene Experimental process: Surface and middle layer preparation: The materials and preparation process of the surface layer and the middle layer are consistent with those in Example 3.

[0054] Bottom layer preparation: The bottom layer consists only of hexagonal boron nitride (15%) and polyimide (85%), without the addition of graphene sheets.

[0055] The mixing, homogenizing and hot pressing process conditions are the same as those in Example 3.

[0056] Comparative Example 5: The calcination temperature of the middle layer fiber is insufficient Experimental process: Surface and bottom layer preparation: The surface layer and bottom layer materials and preparation processes are consistent with those in Example 2.

[0057] Middle layer preparation: The calcination temperature of the nanofibers was set to 350° C. and the calcination time was 2 hours (lower than the optimized parameters of Example 2).

[0058] The other assembly processes (mixing, spin coating, curing) are consistent with those in Example 2.

[0059] Comparative Example 6: No h-BN particles added to the bottom layer Experimental process: Surface and middle layer preparation: The materials and preparation process of the surface layer and the middle layer are consistent with those in Example 3.

[0060] Bottom layer preparation: The bottom layer consists only of a polyimide matrix (100%) without the addition of hexagonal boron nitride (h-BN).

[0061] The mixing and hot pressing process conditions are consistent with those in Example 3.

[0062] Comparative Example 7: Insufficient superhydrophobic particles Experimental process: Surface preparation: The mass fraction of the super-hydrophobic particles was reduced to 1%, and the remaining components and process conditions were consistent with those of Example 4.

[0063] The spin coating, UV curing and thermal curing processes are consistent with those in Example 4.

[0064] Preparation of middle and bottom layers: The materials and preparation processes of the middle layer and the bottom layer are consistent with those of Example 4.

[0065] Experiment 1: Crack self-repair ability test Experimental description: Experimental purpose: Through the needle scratch crack repair test, verify the self-repair ability of the dynamic repair particles in the protective layer of the present invention, analyze the conductive performance recovery ability of the protective layer under damage, and further illustrate the dynamic repair particles (such as Ag + 、Zn 2 + ) in crack self-repair.

[0066] Experimental equipment and materials: Stylus Scratch Instrument (controls scratch depth and width) Electrochemical workstation (for applying electric field and measuring contact resistance) Surface scanning electron microscopy (SEM, used to observe crack healing) Example 1 (containing Ag + Dynamic repair particles), Example 2 (containing Zn 2+ Dynamic repair particles), coating samples of Comparative Example 1 (not containing dynamic repair particles).

[0067] Experimental steps: Crack creation: A crack with a depth of 10 μm and a width of 5 μm was created on the surface of each sample using a stylus marker to simulate mechanical damage. The crack was evenly created along the surface of the sample to create a damaged area with a length of about 1 cm.

[0068] Electric field effect: A DC voltage of 0.5 V was applied to each sample in the electrochemical workstation, and the test time was set to 5 minutes to simulate the process of electric field-driven repair particles migrating to the crack area under actual working conditions.

[0069] Data collection: Contact resistance measurement: The contact resistance of the samples before and after crack repair was recorded using the four-probe method. For each sample, the initial resistance, the resistance after crack generation, and the resistance after repair were recorded.

[0070] Microscopic observation: SEM was used to observe the crack healing, including the reduction of crack width and the morphology of metal deposition.

[0071] Repeat the test: To ensure that the experimental data were statistically significant, each sample was tested three times and the average value was taken as the final data.

[0072] Table 1 Comparative experimental data of crack self-repairing ability of the embodiment and the comparative example. sample Initial contact resistance Resistance after crack damage Resistors after repair Repair efficiency Example 1 0.12Ω 0.68Ω 0.14Ω 97.06％ Example 2 0.14Ω 0.73Ω 0.18Ω 95.07％ Comparative Example 1 0.11Ω 0.65Ω 0.6Ω 7.69％

[0073] The experimental results show that the repair efficiency of Example 1 and Example 2 reached 97.06% and 95.07% respectively, which is much better than 7.69% of Comparative Example 1. This significant difference reflects the dynamic repair of particles (such as Ag + 、Zn 2+ ) plays a key role in crack healing, verifying the significant advantages of the protective layer of the present invention in self-healing performance. In comparative example 1, due to the lack of dynamic repair particles, no metal deposition can be formed at the crack, and the contact resistance is almost not restored, further proving the necessity of repair particles in the protective layer.

[0074] From a mechanistic point of view, this experiment clearly demonstrates the "ion migration-deposition" mechanism of dynamic repair particles. Driven by the electric field, Ag + or Zn 2+ The particles migrate to the crack area through the protective layer and generate a metal film through electrochemical reaction. This repair process not only fills the crack, but also rebuilds the conductive network, so that the contact resistance quickly recovers to a value close to the initial value. + The electrochemical deposition rate of the particles is faster, so the repair efficiency is slightly higher than that of Example 2; 2+ The particle deposition process is slower and the repair efficiency is slightly lower but still excellent.

[0075] In addition, the distribution of dynamic repair particles and the synergistic effect of the matrix are the key to the repair process. The phosphorus-doped polypyrrole matrix provides an efficient electron conduction path for ion migration, and its chemical stability avoids further degradation of the crack area. In contrast, although Comparative Example 1 uses the same matrix material, it lacks the support of repair particles and the conductivity of the crack area cannot be restored, which reflects the creativity of the present invention in material design.

[0076] In summary, the present invention effectively solves the problem of reduced conductivity of the traditional protective layer under crack damage by innovatively introducing dynamic repair particles. This technology not only performs well under laboratory conditions, but also has a wide range of practical application potential, such as significantly extending the service life and improving equipment reliability in electronic connectors with high-frequency mechanical contact.

[0077] Experiment 2: Corrosion resistance test Experimental description: Purpose: The corrosion resistance of the protective layer of the present invention in a salt spray environment is verified, and the improvement of the corrosion resistance by microcapsule corrosion inhibitors and super-hydrophobic particles is analyzed in detail. The technical advantages of the present invention are demonstrated by comparing the change in contact resistance and the surface corrosion state.

[0078] Experimental equipment and materials: Salt spray test chamber (3.5% NaCl solution, temperature 35°C) Electrochemical workstation (for measuring contact resistance) Optical microscope (for observing surface corrosion) Coating samples of Example 1, Example 2, Comparative Example 1 (without dynamic repair particles), and Comparative Example 3 (without corrosion inhibitor) Experimental steps: Sample preparation: Each group of samples was prepared under the same conditions, and the surface was evenly coated with a protective layer with a thickness controlled at about 20 μm.

[0079] The samples were grouped into: Example 1, Example 2, Comparative Example 1, Comparative Example 3.

[0080] Salt spray test: The sample was fixed in a salt spray test chamber and exposed to a salt spray environment of 3.5% NaCl solution. The temperature was set at 35°C and the total test time was 500 hours.

[0081] Samples were taken every 100 hours and the change in contact resistance was measured using an electrochemical workstation.

[0082] Surface observation: After each sampling, an optical microscope was used to observe the distribution and expansion of corrosion spots on the sample surface, and the area and density of the corrosion spots were recorded.

[0083] Data Records: The initial contact resistance, contact resistance at each time point and corrosion spot conditions were recorded, and the data were used for comparative analysis.

[0084] Table 2: Experimental data of corrosion resistance comparison between examples and comparative examples sample Initial contact resistance 100 hours contact resistance 300 hours contact resistance 500 hours contact resistance Example 1 0.12Ω 0.13Ω 0.15Ω 0.18Ω Example 2 0.14Ω 0.15Ω 0.18Ω 0.21Ω Comparative Example 1 0.11Ω 0.19Ω 0.32Ω 0.54Ω Comparative Example 3 0.13Ω 0.22Ω 0.39Ω 0.61Ω The experimental data show that the contact resistance of Example 1 and Example 2 increased by 0.06Ω and 0.07Ω respectively after 500 hours of salt spray test, and the corrosion spot area was only 0.5mm 2 and 0.8mm 2 In contrast, the contact resistance of Comparative Examples 1 and 3 increased significantly, reaching 0.54Ω and 0.61Ω respectively, and the area of ​​the corrosion spots increased significantly, indicating that the corrosion spread rapidly on their surfaces. This result shows that the microcapsule corrosion inhibitor and super-hydrophobic particles play a decisive role in the corrosion resistance of the protective layer in a long-term salt spray environment.

[0085] From the perspective of mechanism, the improvement of corrosion resistance of Example 1 and Example 2 is attributed to two aspects: first, the microcapsule corrosion inhibitor slowly releases antioxidants (such as vitamin E or imidazole compounds) to form a dense protective film on the metal surface, which significantly reduces the corrosion medium (such as Cl - )’s intrusion rate, slowing down the corrosion reaction. Secondly, the super-hydrophobic nanoparticles in the surface layer construct a micro-nano structure with low surface energy, making it difficult for water droplets and salt spray to adhere to the coating surface, effectively preventing the penetration of corrosive media.

[0086] In Comparative Examples 1 and 3, due to the lack of dynamic repair particles and corrosion inhibitors, respectively, the protective layer cannot provide effective protection at the cracks or metal exposed areas, resulting in rapid corrosion expansion and a significant increase in contact resistance. This shows that in the design of the protective layer, the synergistic effect of the corrosion inhibitor and the super-hydrophobic particles is crucial to the corrosion resistance, and the dynamic repair particles, although secondary, also play an auxiliary role in the repair after mechanical damage.

[0087] In summary, the present invention achieves a significant improvement in the stability of the protective layer in a long-term corrosive environment through the innovative design of microcapsule corrosion inhibitors and super-hydrophobic particles. Combined with actual application scenarios, this design is very suitable for use in contact devices that are susceptible to corrosion, such as circuit board contacts and electronic connectors, to extend the service life of the equipment and reduce maintenance costs. The experiment further verified the rational design of the functional components in the protective layer material and their synergistic effect, reflecting the creativity and technical value of the present invention.

[0088] Experiment 3: Wear resistance test Experimental description: Experimental purpose: Through friction and wear tests, verify the wear resistance of the protective layer of the present invention under mechanical stress, focus on analyzing the effect of different material layers (such as dynamic repair particles and TiO2 nanofibers) on friction loss, and verify the stability of the protective layer under long-term mechanical stress.

[0089] Experimental equipment and materials: Friction and wear tester (loading force 10N, friction path length 10mm) Four-probe resistance measurement device (for testing contact resistance) Coating samples of Example 1, Comparative Example 3 (no corrosion inhibitor), and Comparative Example 5 (insufficient fiber calcination temperature) Experimental steps: Sample preparation: Each group of samples was prepared according to the preparation method of the embodiment or comparative example, and the coating thickness was controlled at 20 μm.

[0090] After curing, the sample was fixed on the sample holder of the friction and wear tester.

[0091] Friction test: Test conditions: loading force 10N, friction speed 50mm / s, reciprocating friction path length 10mm, and the total number of friction cycles was set to 20,000 times.

[0092] The contact resistance of the sample was recorded every 5,000 times during the friction process, and the wear of the sample surface was observed.

[0093] Thickness measurement: After the test, a thickness gauge is used to record the thickness change of the protective layer after wear and calculate the thickness loss.

[0094] Surface observation: The surface of the sample after friction was observed using an optical microscope to record the crack extension and protective layer peeling.

[0095] Table 3: Experimental data of wear resistance comparison between the embodiment and the comparative example sample Initial contact resistance Contact resistance after friction Thickness loss Crack length Example 1 0.12Ω 0.15Ω 2.1μm 0.5mm Comparative Example 3 0.13Ω 0.28Ω 5.4μm 1.5mm Comparative Example 5 0.14Ω 0.33Ω 7.8μm 2.3mm The experimental results show that after 20,000 friction cycles, the contact resistance of Example 1 only increased by 0.03Ω, the thickness loss of the protective layer was 2.1μm, the crack length was about 0.5mm, and the surface remained intact without obvious peeling. However, Comparative Examples 3 and 5 showed significant degradation, with contact resistance increased by 0.15Ω and 0.19Ω, respectively, and the thickness loss of the protective layer was 5.4μm and 7.8μm, respectively, and the crack extended to 1.5mm and 2.3mm. These data show that the dynamic repair particles and TiO2 nanofibers in the present invention play an important role in improving the wear resistance of the protective layer.

[0096] From the perspective of mechanism, the dynamic repair particles (Ag + or Zn 2+) During the process of friction-induced cracks, the crack area is repaired by electrochemical deposition, while the network structure of TiO2 nanofibers provides additional mechanical strength, inhibiting further crack expansion. The deposition of dynamic repair particles not only restores the integrity of the conductive network, but also effectively reduces the stress concentration at the crack, allowing the protective layer to maintain a stable structure and performance during repeated friction.

[0097] In contrast, due to the lack of corrosion inhibitor, the cracks exposed during the friction process in Comparative Example 3 could not form an anti-corrosion protective film, resulting in rapid crack expansion and large-area shedding of the protective layer. In Comparative Example 5, the TiO2 fiber was not calcined at an adequate temperature, resulting in poor mechanical properties and interface bonding of the fiber, and the protective layer was prone to peeling and abrasion under friction stress, thereby significantly reducing the wear resistance.

[0098] The experimental results further prove that the calcination temperature of TiO2 fiber and the coordinated design of dynamic repair particles are crucial to the wear resistance of the protective layer. TiO2 fiber provides mechanical support, while dynamic repair particles provide conductivity and local repair ability at the damaged part. The combination of the two makes Example 1 show excellent stability in the friction damage test. Combined with the application scenario, this design is particularly suitable for high-frequency mechanical contact scenarios, such as electronic equipment connectors and automotive electrical interfaces, which greatly improves the service life of contacts and reduces maintenance frequency.

[0099] Experiment 4: Thermal conductivity test Experimental description: Experimental purpose: To verify the thermal conductivity of the protective layer of the present invention in a high-power current or heat source environment, focusing on analyzing the role of the underlying thermal conductivity design (graphene sheets and hexagonal boron nitride), and to prove the innovation of the present invention by comparing the surface temperature rise and thermal conductivity.

[0100] Experimental equipment and materials: Infrared thermal imager (used to record the temperature distribution on the sample surface) Laser thermal conductivity meter (used to test the thermal conductivity of samples) Constant power heat source (power 5W, bottom temperature 50℃) Coating samples of Example 3 (co-designed with graphene and h-BN), Comparative Example 4 (without graphene), and Comparative Example 6 (without h-BN) Experimental steps: Sample preparation: The coating samples of Example 3, Comparative Example 4 and Comparative Example 6 were prepared to ensure that the sample sizes were the same and the coating thickness was about 20 μm.

[0101] Fix the sample on a constant power heat source, ensuring that the bottom of the heat source maintains a constant temperature of 50°C and covers the entire bottom surface of the sample.

[0102] Surface temperature record: The heat source was started and heating was continued for 60 min, and the temperature distribution on the sample surface was recorded using an infrared thermal imager.

[0103] Surface temperatures were recorded every 15 minutes and hot spots were marked and counted.

[0104] Thermal conductivity test: The thermal conductivity of the sample was tested using a laser thermal conductivity meter. The test was repeated three times according to the standard method and the average value was taken.

[0105] Data recording and analysis: Record the maximum surface temperature, temperature rise and thermal conductivity of the sample for comparative analysis.

[0106] Table 4: Experimental data on thermal conductivity comparison between the examples and the comparative examples sample Initial surface temperature Surface temperature after 30 minutes Surface temperature after 60 minutes Thermal conductivity Example 3 50℃ 53.5℃ 55.2℃ 1.52W / m·K Comparative Example 4 50℃ 55.8℃ 59.7℃ 0.92W / m·K Comparative Example 6 50℃ 57℃ 61.3℃ 0.73W / m·K Experimental data show that the surface temperature rise of Example 3 after 60 minutes of heating is only 5.2°C, and its thermal conductivity reaches 1.52W / m·K, showing excellent thermal conductivity. The surface temperature rise of Comparative Examples 4 and 6 reaches 9.7°C and 11.3°C, respectively, and the thermal conductivity is only 0.92W / m·K and 0.73W / m·K, respectively, indicating that the lack of graphene or hexagonal boron nitride will significantly reduce the thermal conductivity of the protective layer. The experimental results fully verify the key role of the collaborative design of graphene and h-BN in thermal management.

[0107] From a mechanistic analysis, the excellent thermal conductivity of Example 3 is derived from the synergistic effect of graphene sheets and h-BN particles. Graphene has an extremely high in-plane thermal conductivity (>2000W / m·K) and can quickly conduct heat, while h-BN further optimizes the heat transfer path through its two-dimensional layered structure to form a multi-directional heat conduction network. This design not only improves the overall thermal conductivity, but also significantly reduces the hot spot effect on the sample surface, ensuring the stability of the protective layer under high power current or heat source conditions.

[0108] In contrast, Comparative Example 4 lacks graphene sheets, and its thermal conduction path mainly relies on h-BN, resulting in reduced heat transfer efficiency and higher surface temperature rise; Comparative Example 6 lacks the support of h-BN, and the thermal conduction path composed of graphene alone cannot cover the heat flow distribution in the three-dimensional structure, and the thermal management capability is further degraded. The experiment clearly shows that a single thermal conductive material is not enough to meet the heat dissipation requirements in high-power scenarios, and the synergistic effect of graphene and h-BN can significantly optimize thermal conductivity.

[0109] Combined with actual application scenarios, the protective layer design of the present invention is particularly suitable for high-power electronic equipment or high-temperature environments (such as new energy vehicle electrical interfaces or industrial equipment terminals), effectively reducing the temperature accumulation on the surface of the equipment and extending the service life of the equipment. The experimental results not only verify the scientific nature of the material layer design, but also highlight the significant advantages of the present invention in thermal management capabilities, further consolidating the technical innovation and industrial application value of the present invention.

[0110] Experiment 5: Comprehensive Performance Evaluation Experimental description: Experimental purpose: By simulating complex actual application scenarios, verify the advantages of the protective layer of the present invention in terms of wear resistance, corrosion resistance and thermal conductivity. The experiment uses mechanical wear, salt spray corrosion and high temperature environment combined stress as test conditions to comprehensively evaluate the stability and reliability of the protective layer.

[0111] Experimental equipment and materials: Friction and wear tester (loading force 10N, friction path length 10mm) Salt spray test chamber (3.5% NaCl solution, temperature 35°C) Infrared thermal imager (recording sample surface temperature distribution) Coating samples of Example 4 (comprehensive optimization design), Comparative Example 1 (no dynamic repair particles), Comparative Example 3 (no corrosion inhibitor), and Comparative Example 6 (no h-BN) Experimental steps: Sample preparation: The coating samples of Example 4, Comparative Example 1, Comparative Example 3 and Comparative Example 6 were prepared, and the coating thickness was controlled to be 20 μm.

[0112] Each set of samples was labeled and grouped separately for use in different testing phases.

[0113] Joint experiment process: Friction test: The samples were subjected to reciprocating friction tests using a friction and wear tester with a load of 10N, a friction speed of 50mm / s, a friction path length of 10mm, and a test cycle of 20,000 times. The contact resistance and thickness loss after friction were recorded.

[0114] Salt spray corrosion test: The friction samples were subjected to a salt spray test. The samples were exposed to a 3.5% NaCl solution at a temperature of 35°C for 500 hours. The changes in contact resistance were recorded and the corrosion status was observed.

[0115] High temperature test: Using a constant power heat source (power 5W, bottom temperature 50°C), the sample was heated continuously for 60 minutes, the surface temperature distribution was recorded, and the thermal management performance was tested.

[0116] Data recording and analysis: The contact resistance change, thickness loss, corrosion spot area and surface temperature of the samples at each test stage were recorded, and the comprehensive performance of each sample was analyzed.

[0117] Table 5: Experimental data of comprehensive performance comparison between examples and comparative examples sample Contact resistance after friction Thickness loss Contact resistance after salt spray Corrosion spot area Example 4 0.15Ω 2.5μm 0.18Ω <![CDATA[0.6mm 2 ]]> Comparative Example 1 0.62Ω 6.2μm 0.76Ω <![CDATA[3.8mm 2 ]]> Comparative Example 3 0.48Ω 5.4μm 0.68Ω <![CDATA[4.2mm 2 ]]> Comparative Example 6 0.52Ω 7.5μm 0.8Ω <![CDATA[4.6mm 2 ]]> The experimental data show that Example 4 exhibits excellent stability and reliability in the comprehensive test: the contact resistance after friction only increases by 0.03Ω, the thickness loss is 2.5μm, the contact resistance after salt spray corrosion is only 0.18Ω, and the surface corrosion spot area is only 0.6mm 2 , after 60 minutes of heating, the surface temperature rise is the smallest, which is only 5.0° C. In contrast, Comparative Examples 1, 3 and 6 all show significant degradation in multiple properties.

[0118] From the mechanism analysis, the excellent comprehensive performance of Example 4 comes from the synergistic effect of the multi-layer protection structure. + or Zn 2+ ) The conductive network is effectively repaired by electrochemical deposition at the cracks, resulting in minimal change in contact resistance after friction; TiO2 nanofibers provide additional mechanical strength, significantly inhibit the expansion of cracks during friction, and reduce thickness loss. Microcapsule corrosion inhibitors slowly release effective antioxidants in a salt spray environment, forming a protective film at cracks and exposed areas, reducing the generation of corrosion spots, while super-hydrophobic particles further prevent the intrusion of moisture and salt spray. In addition, the thermal conductive network synergistically constructed by graphene and h-BN in the bottom layer ensures thermal management performance under high temperature conditions and keeps the surface temperature rise to a minimum.

[0119] In contrast, Comparative Example 1 lacks dynamic repair particles, and the conductive network at the crack cannot be restored after friction, resulting in a significant increase in contact resistance; Comparative Example 3 lacks corrosion inhibitors, and a protective film cannot be formed after the crack is exposed, and the area of ​​the corrosion spots in the salt spray test is significantly enlarged; Comparative Example 6 lacks h-BN particles, and the thermal conductivity of the protective layer is significantly reduced, and the surface temperature rise is higher, indicating insufficient thermal management capabilities. These results verify the significant advantages of the innovative design of the protective layer of the present invention in terms of wear resistance, corrosion resistance and thermal conductivity.

[0120] This experiment fully simulated the complex stress scenarios in actual applications, and the results clearly showed that the present invention solved the problem of performance degradation of the traditional protective layer under mechanical damage, corrosive environment and heat source conditions through the multifunctional layered structure design. Especially in high-frequency mechanical contact and high-power current application scenarios, such as electronic connectors and automotive electrical interfaces, Example 4 can significantly improve the reliability and service life of the contacts, fully reflecting the industrial application value and technical advantages of the present invention.

[0121] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A contact protection layer of a conductive terminal, characterized in that: The protective layer comprises the following layered structure: Surface layer: contains phosphorus-doped polypyrrole matrix, dynamic repair particles and superhydrophobic nanoparticles; Middle layer: contains nanofibers, microcapsule corrosion inhibitors, graphene sheets and polysiloxane matrix; Bottom layer: contains hexagonal boron nitride particles and polyimide matrix.

2. The contact protection layer of the conductive terminal according to claim 1, characterized in that: The mass fraction of the phosphorus-doped polypyrrole matrix is ​​60%-80%, the mass fraction of the dynamic repair particles is 5%-10%, and the mass fraction of the super-hydrophobic nanoparticles is 2%-5%.

3. The contact protection layer of the conductive terminal according to claim 1, characterized in that: The dynamic repair particles are Ag + or Zn 2+ The super hydrophobic nanoparticles are surface-modified silica particles with a particle size range of 50-200 nm.

4. The contact protection layer of the conductive terminal according to claim 1, characterized in that: The nanofibers in the middle layer are titanium titanate nanofibers with a diameter of 10-20 nm. The microcapsule corrosion inhibitor is a microcapsule encapsulating an imidazole compound or vitamin E with a mass fraction of 2%-5%.

5. The contact protection layer of the conductive terminal according to claim 1, characterized in that: The graphene sheet is multilayer graphene with a thickness of 0.34 nm and a mass fraction of 2%-5%; the mass fraction of the polysiloxane matrix is ​​70%-80%.

6. The contact protection layer of the conductive terminal according to claim 1, characterized in that: The particle size of the hexagonal boron nitride particles in the bottom layer is 1-2 μm, and the mass fraction is 10%-20%; the mass fraction of the polyimide matrix is ​​80%-90%.

7. A method for preparing a contact protection layer of a conductive terminal, characterized in that: The following steps are involved: (1) Preparing the surface layer: mixing phosphorus-doped polypyrrole, dynamic repair particles, super-hydrophobic nanoparticles and photosensitive active molecules, coating, and curing including ultraviolet light curing and thermal curing; (2) preparing the intermediate layer: mixing the nanofibers with the microcapsule corrosion inhibitor, the graphene sheet and the polysiloxane matrix, coating them and curing them at room temperature; (3) Preparation of the bottom layer: The hexagonal boron nitride particles are mixed with the polyimide matrix, coated and formed by high-pressure hot pressing.

8. The method for preparing a contact protection layer of a conductive terminal according to claim 7, characterized in that: The coating process of the surface layer is a spin coating process, the spin coating speed is 1000-3000rpm, the time is 10-30 seconds; the light intensity of ultraviolet light curing is 500-700mW / cm 2 , the thermal curing temperature is 120-150°C and the time is 1-2 hours.

9. The method for preparing a contact protection layer of a conductive terminal according to claim 7, characterized in that: The nanofibers of the middle layer are prepared by electrospinning, the electrospinning voltage is 15-20 kV, the flow rate is 0.5-1.0 mL / h, the spinning collection distance is 10-15 cm; the calcination temperature is 400-500° C., and the calcination time is 2-3 hours.

10. The method for preparing a contact protection layer of a conductive terminal according to claim 7, characterized in that: The hexagonal boron nitride particles of the bottom layer and the polyimide matrix are mixed by high-pressure homogenization technology, and the homogenization pressure is 30-50MPa; the temperature of hot pressing molding is 180-200°C, the pressure is 5-10MPa, and the time is 1-2 hours.

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