Contact protection layer for electrically conductive terminals and method for producing same

Abstract

The application relates to the technical field of conductive materials, and discloses a contact protection layer of a conductive terminal and a preparation method thereof. The protection layer is composed of a dynamic self-repairing conductive layer, a nano-fiber reinforced slow-release layer and a high-thermal-conductivity wear-resistant layer. Through the synergistic design of the multi-layer structure, the comprehensive improvement of crack self-repairing, corrosion resistance, thermal conductivity and wear resistance is realized. The dynamic self-repairing conductive layer contains phosphorus-doped polypyrrole and dynamic repair particles, and the crack is repaired and the conductive network is restored through electrochemical deposition; the nano-fiber reinforced slow-release layer combines TiO2 nano-fibers and corrosion inhibitors to provide crack inhibition and corrosion protection functions; and the high-thermal-conductivity wear-resistant layer is composed of a thermal conduction network formed by graphene and hexagonal boron nitride, so that the heat management performance is optimized and the mechanical strength is improved. The protection layer effectively solves the problem that the performance of the contact protection layer in the prior art is deteriorated due to crack propagation and mechanical damage, and significantly improves the long-term stability, wear resistance and corrosion resistance.

Description

TECHNICAL FIELD

[0001] The present application 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

[0002] In modern electronic devices, conductive terminals are widely used in fields such as circuit board connectors, electronic device contact points, and automobile electrical interfaces, and their main function is to achieve reliable electrical signal transmission and energy distribution. With the increasing demand for performance of electronic devices, the stability and durability of the contact points of conductive terminals are increasingly required, especially under conditions of high-frequency mechanical contact, complex environments (such as high humidity and high salt fog), and high-power current, their performance directly affects the overall reliability and service life of the device.

[0003] In the prior art, the contact protection layer of the conductive terminal usually adopts a single functional coating or a metal plating layer (such as gold plating, silver plating, or alloy coating) to improve the conductivity and corrosion resistance. In addition, some research has also tried to add corrosion-resistant coatings, wear-resistant coatings, and other ways to improve the corrosion resistance and wear resistance of the contact points. However, these methods still have great limitations, for example, the metal plating layer is prone to wear and tear 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 lacks heat management capability in high-power current environments, which is prone to high temperature rise, further reducing the stability of the protection layer.

[0004] The main problem of the prior art 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 conductivity. This degradation problem caused by cracks not only affects the reliability of the conductive terminal, but also significantly shortens its service life, increasing the cost of device maintenance and replacement. SUMMARY

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

[0006] To achieve the above purpose, the present application realizes the following technical scheme: a contact protection layer of a conductive terminal, the protection layer comprising the following layered structure:

[0007] Surface layer: containing phosphorus-doped polypyrrole matrix, dynamic repair particles, and super-hydrophobic nanoparticles;

[0008] Intermediate layer: containing nanofibers, microcapsule corrosion inhibitor, graphene sheet, and polysiloxane matrix;

[0009] Bottom layer: containing hexagonal boron nitride particles and polyimide matrix.

[0010] 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 super-hydrophobic nanoparticles is 2%-5%.

[0011] 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.

[0012] 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%.

[0013] Preferably, the graphene sheet is a multi-layer graphene with a thickness of 0.34 nm and a mass fraction of 2%-5%, and the polysiloxane matrix has a mass fraction of 70%-80%.

[0014] Preferably, the hexagonal boron nitride particles in the bottom layer have a particle size of 1-2 μm and a mass fraction of 10%-20%, and the polyimide matrix has a mass fraction of 80%-90%.

[0015] The method for preparing the contact protection layer of the conductive terminal comprises the following steps:

[0016] (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;

[0017] (2) Preparing the intermediate layer: mixing nanofibers with microcapsule corrosion inhibitors, graphene sheets, and polysiloxane matrix, coating, and curing at room temperature;

[0018] (3) Preparing the bottom layer: mixing hexagonal boron nitride particles with a polyimide matrix, coating, and forming by high-pressure hot pressing.

[0019] Preferably, the coating process of the surface layer is spin coating with a spin coating speed of 1000-3000 rpm for 10-30 seconds; the light intensity for ultraviolet light curing is 500-700 mW / cm 2 , the thermal curing temperature is 120-150 °C, and the time is 1-2 hours.

[0020] Preferably, the nanofibers of the intermediate layer are prepared by electrospinning, the electrospinning voltage is 15-20kV, the flow rate is 0.5-1.0mL / h, the spinning collection distance is 10-15cm; the calcination temperature is 400-500℃, and the calcination time is 2-3 hours.

[0021] Preferably, the mixing of the hexagonal boron nitride particles and the polyimide matrix of the bottom layer adopts high-pressure homogenization technology, the homogenization pressure is 30-50MPa; the temperature of hot-pressing forming is 180-200℃, the pressure is 5-10MPa, and the time is 1-2 hours.

[0022] The application provides a contact protection layer of an electrically conductive terminal and a preparation method thereof.

[0023] 1. The application 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, and achieves the synergistic optimization effect of crack self-repairing, corrosion resistance, wear resistance and high thermal conductivity.

[0024] 2. The application adopts Ag + or Zn 2+ The dynamic repair particles complete crack repair through an electrochemical deposition mechanism, and achieve the technical effect of rapid crack filling and recovery of electrical conductivity.

[0025] 3. The application adopts the technical scheme of a microcapsule corrosion inhibitor and nanofiber composite design, and achieves the technical effect of slow release of antioxidants and continuous inhibition of metal oxidation in a corrosive medium environment.

[0026] 4. The application adopts the technical scheme of a bottom layer composed of hexagonal boron nitride and a polyimide matrix, and achieves the technical effect of combining high thermal conductivity and wear resistance. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 The flowchart of the method of the application is shown. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described with reference to the drawings in the specification of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0029] Please refer to the drawings in the specification of the present application Figure 1 The embodiments of the present application provide a contact protection layer of a conductive terminal and a preparation method thereof, which comprises:

[0030] 1. Surface layer preparation (dynamic self-repairing conductive layer)

[0031] 1.1 Preparation of raw materials:

[0032] Dissolve the pyrrole monomer in N,N-dimethylformamide (DMF), add phosphate (dopant, mass fraction 3%), and stir uniformly at 25°C for 1 hour. Then, add 5% (mass fraction) of dynamic repair particles (AgCl-PEG complex) and 3% of super-hydrophobic nano-silicon dioxide particles (particle size 50-100 nm), and ultrasonic dispersion for 20 minutes (ultrasonic power 120 W).

[0033] 1.2 Coating and curing:

[0034] Coat the prepared solution on the surface of the conductive terminal by the spin coating process, the spin coating speed is 2000 rpm, and the time is 15 seconds, to form a uniform coating. Then, perform a double curing process:

[0035] UV curing: UV intensity 600 mW / cm 2 , time 20 minutes;

[0036] Thermal curing: temperature 130°C, time 1.5 hours.

[0037] 2. Preparation of the intermediate layer (nanofiber reinforced slow-release layer)

[0038] 2.1 Preparation of nanofibers:

[0039] Dissolve tetrabutyl titanate (10 wt%) in ethanol to prepare a precursor solution; form a fiber membrane by the electrospinning process (voltage 18 kV, flow rate 0.8 mL / h, collection distance 12 cm). The fiber membrane is calcined at 450°C for 2 hours to obtain TiO2 nanofibers with a diameter of 10-20 nm.

[0040] 2.2 Assembly of the functional layer:

[0041] 10% TiO2 nanofiber mixed with 5% microcapsule corrosion inhibitor (encapsulated vitamin E) is dispersed in 80% polysiloxane solution, and uniformly spin-coated to the surface layer at a spin-coating speed of 1500 rpm and a coating thickness of 8-10 μm. Curing at room temperature for 24 hours.

[0042] 3. Bottom layer preparation (high thermal conductivity and wear-resistant layer)

[0043] 15% hexagonal boron nitride (h-BN) particles are mixed with 85% polyimide (PI) solution, stirred at a temperature of 45°C for 2 hours, and uniformly dispersed by a high-pressure homogenization device (pressure 40 MPa). After coating under the intermediate layer, it is formed by a hot pressing process (temperature 190°C, pressure 7 MPa, time 2 hours) to form a bottom layer with a thickness of about 15 μm.

[0044] Effect verification:

[0045] Salt spray test: no obvious corrosion spots and contact resistance increase <1% after 500 hours of testing in 3.5% NaCl solution.

[0046] Friction test: contact resistance change <3% after 20,000 times of loading 10N friction.

[0047] Repair test: crack depth 10 μm, repair time <5 minutes, repair rate >95%.

[0048] Example 2: Preparation of conductive terminal contact protection layer with enhanced corrosion resistance

[0049] Surface layer adjustment:

[0050] On the basis of the surface layer preparation in Example 1, Zn 2+ Composite (mass fraction 6%) instead of Ag + , further enhancing the dynamic repair ability in corrosive environment.

[0051] Coating and curing conditions remain unchanged.

[0052] Intermediate layer optimization:

[0053] Microcapsule corrosion inhibitor uses imidazole compound (mass fraction 3%) instead of vitamin E to improve corrosion resistance in alkaline environment.

[0054] The electrospinning conditions are adjusted to a voltage of 20 kV, a calcination temperature of 500°C, and a calcination time of 3 hours to further improve the mechanical strength of the fibers.

[0055] Effect verification:

[0056] Corrosion resistance: salt spray test extended to 1000 hours, no obvious corrosion spots on the surface of the protective layer, and contact resistance increase <2%.

[0057] Example 3: Preparation of conductive terminal contact protection layer with improved thermal conductivity

[0058] Bottom layer enhancement design:

[0059] In the bottom layer preparation, 3% (mass fraction) graphene sheets were added to form a thermal conduction network with h-BN.

[0060] The homogenization conditions were adjusted to a pressure of 50 MPa and a mixing time of 15 minutes to ensure uniform distribution of graphene and h-BN in the PI matrix.

[0061] Effect verification:

[0062] Thermal conductivity test: The thermal conductivity was improved to 1.5 W / m·K (50% higher than Example 1), effectively slowing down the material degradation caused by current.

[0063] Example 4: Preparation of high-humidity environment-resistant protection layer

[0064] Surface layer improvement:

[0065] In the surface layer preparation, the amount of super-hydrophobic nanoparticles was increased to 5% (mass fraction) to improve the waterproof performance.

[0066] The photosensitive active molecule was replaced with tetraphenylporphyrin (mass fraction 2%), and the surface layer was further densified through photosensitive polymerization.

[0067] Effect verification:

[0068] High-humidity environment test: After 1000 hours of exposure in an environment with humidity of 95% and temperature of 35℃, the contact resistance of the protection layer changed by <1%.

[0069] Example 5: Preparation of protection layer with comprehensive performance optimization

[0070] Full layer optimization:

[0071] The surface layer, slow-release layer, and bottom layer were combined using the optimization design methods of Example 2, Example 3, and Example 4, respectively, to form a multi-layer protection layer with comprehensive performance optimization.

[0072] Effect verification:

[0073] Salt spray test: No corrosion for 1000 hours;

[0074] Friction test: Contact resistance change <5% for 30,000 times;

[0075] High temperature test: Conductivity remained stable at 85℃, with a resistance change of <3%.

[0076] Comparative Example 1: Protection layer without dynamic repair particles

[0077] Experimental procedure:

[0078] Surface layer preparation:

[0079] The surface layer used phosphorous-doped polypyrrole (mass fraction 80%) and superhydrophobic nanoparticles (mass fraction 5%), but no dynamic repair particles such as Ag + or Zn 2+ .

[0080] 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).

[0081] Spin coating process: 2000 rpm, time 15 seconds; UV curing and thermal curing conditions were the same as Example 1.

[0082] Middle layer and bottom layer preparation:

[0083] The middle layer and bottom layer materials and preparation process were completely consistent with Example 1.

[0084] Comparative Example 2: Surface layer not doped with phosphate

[0085] Experimental procedure:

[0086] Surface layer preparation:

[0087] The surface layer used undoped polypyrrole as the base material (mass fraction 80%), and the remaining components included dynamic repair particles (mass fraction 5%) and superhydrophobic nanoparticles (mass fraction 5%).

[0088] The spin coating process, UV curing, and thermal curing conditions were consistent with Example 1.

[0089] Middle layer and bottom layer preparation:

[0090] The middle layer and bottom layer materials and preparation process were completely consistent with Example 1.

[0091] Comparative Example 3: Middle layer does not contain corrosion inhibitor

[0092] Experimental procedure:

[0093] Surface layer and bottom layer preparation:

[0094] The surface layer and bottom layer materials and preparation process were consistent with Example 1.

[0095] Middle layer preparation:

[0096] The middle layer was composed only of TiO2 nanofibers (mass fraction 10%) and polysiloxane (mass fraction 90%), without the addition of microcapsule corrosion inhibitors.

[0097] Nanofiber preparation, mixing, spin coating and curing processes were identical to Example 1.

[0098] Comparative Example 4: Bottom layer without graphene

[0099] Experimental procedure:

[0100] Top and middle layers preparation:

[0101] Top and middle layers materials and preparation processes were identical to Example 3.

[0102] Bottom layer preparation:

[0103] The bottom layer was composed only of hexagonal boron nitride (15%) and polyimide (85%) without the addition of graphene sheets.

[0104] Mixing, homogenization and hot-pressing process conditions were identical to Example 3.

[0105] Comparative Example 5: Insufficient calcination temperature of middle layer fibers

[0106] Experimental procedure:

[0107] Top and bottom layers preparation:

[0108] Top and bottom layers materials and preparation processes were identical to Example 2.

[0109] Middle layer preparation:

[0110] The calcination temperature of the nanofibers was set to 350°C for 2 hours (lower than the optimized parameters of Example 2).

[0111] Other assembly processes (mixing, spin coating, curing) were identical to Example 2.

[0112] Comparative Example 6: Bottom layer without h-BN particles

[0113] Experimental procedure:

[0114] Top and middle layers preparation:

[0115] Top and middle layers materials and preparation processes were identical to Example 3.

[0116] Bottom layer preparation:

[0117] The bottom layer was composed only of a polyimide matrix (100%) without the addition of hexagonal boron nitride (h-BN).

[0118] Mixing and hot-pressing process conditions were identical to Example 3.

[0119] Comparative Example 7: Insufficient superhydrophobic particles

[0120] Experimental procedure:

[0121] Surface layer preparation:

[0122] The mass fraction of superhydrophobic particles was reduced to 1%, and the remaining components and process conditions were consistent with Example 4.

[0123] The spin coating, UV curing and thermal curing processes were consistent with Example 4.

[0124] Middle layer and bottom layer preparation:

[0125] The materials and preparation processes of the middle layer and the bottom layer were consistent with Example 4.

[0126] Experiment 1: Crack self-repairing ability test

[0127] Experiment description:

[0128] Purpose of the experiment: Through the needle crack repair test, the self-repairing ability of the dynamic repair particles in the protective layer of the application is verified, the conductivity recovery ability of the protective layer under damage is analyzed, and the mechanism of the dynamic repair particles (such as Ag + , Zn 2 + ) in crack self-repairing is further explained.

[0129] Experimental equipment and materials:

[0130] Needle scratch tester (control scratch depth and width)

[0131] Electrochemical workstation (for applying electric field and measuring contact resistance)

[0132] Surface scanning electron microscope (SEM, for observing crack healing)

[0133] Coating samples of Example 1 (containing Ag + dynamic repair particles), Example 2 (containing Zn 2+ dynamic repair particles), and Comparative Example 1 (without dynamic repair particles).

[0134] Experimental steps:

[0135] Crack manufacturing: Use the needle scratch tester to manufacture a crack with a depth of 10 μm and a width of 5 μm on the surface of each sample to simulate mechanical damage. The crack is evenly drawn along the sample surface to form a damage area with a length of about 1 cm.

[0136] Electric field action: Apply a direct current voltage of 0.5 V to each sample in the electrochemical workstation, and set the test time to 5 minutes to simulate the process of driving repair particles to migrate to the crack area under actual working conditions.

[0137] Data collection:

[0138] Contact resistance measurement: Four-probe method was used to record the contact resistance values of samples before and after crack repair. The initial resistance, resistance after crack generation, and resistance after repair were recorded for each sample.

[0139] Microscopic observation: SEM was used to observe the crack healing, including the reduction of crack width and the morphology of metal deposition.

[0140] Repeated tests:

[0141] To ensure the statistical significance of experimental data, 3 repeated tests were conducted for each sample, and the average value was taken as the final data.

[0142] Table 1 Comparison of crack self-repairing ability between examples and comparative examples.

[0143] Sample Initial contact resistance Resistance after crack damage Resistance after repair Repair efficiency Example 1 0.12 Ω 0.68 Ω 0.14 Ω 97.06％ Example 2 0.14 Ω 0.73 Ω 0.18 Ω 95.07％ Comparative Example 1 0.11 Ω 0.65 Ω 0.6 Ω 7.69％

[0144] The experimental results show that the repair efficiency of Examples 1 and 2 reached 97.06% and 95.07%, respectively, which is much better than 7.69% of Comparative Example 1. This significant difference reflects the core role of dynamic repair particles (such as Ag + , Zn 2+ ) in crack healing, and verifies the significant advantage of the protective layer in self-repairing performance. Comparative Example 1 lacks dynamic repair particles and cannot form metal deposition at the crack, so the contact resistance is almost not restored, further proving the necessity of repair particles in the protective layer.

[0145] From the mechanism, this experiment clearly reflects the "ion migration-deposition" mechanism of dynamic repair particles. Under the driving of the electric field, Ag + or Zn 2+ particles migrate through the protective layer to the crack area and form 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 near the initial value. In Example 1, the electrochemical deposition rate of Ag + particles is faster, so the repair efficiency is slightly higher than that of Example 2; while the deposition process of Zn 2+ particles is slower, the repair efficiency is slightly inferior but still excellent.

[0146] In addition, the distribution of dynamic repair particles and the synergy 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 invention in material design.

[0147] In summary, the present application effectively solves the problem of the decline in the conductive performance of the traditional protective layer under crack damage by the innovative introduction of dynamic repair particles. This technology not only performs excellently under laboratory conditions, but also has wide practical application potential, such as in electronic connectors with high-frequency mechanical contact, greatly extending the service life and improving the reliability of equipment.

[0148] Experiment 2: Corrosion Resistance Test

[0149] Experiment Description:

[0150] Experiment Purpose:

[0151] The corrosion resistance of the protective layer in a salt spray environment is verified, and the improvement of the corrosion resistance by the microcapsule corrosion inhibitor and the super-hydrophobic particles is analyzed. By comparing the contact resistance change and the surface corrosion state, the technical advantages of the present application are demonstrated.

[0152] Experimental Equipment and Materials:

[0153] Salt spray test chamber (3.5% NaCl solution, temperature 35°C)

[0154] Electrochemical workstation (for measuring contact resistance)

[0155] Optical microscope (for observing surface corrosion)

[0156] Coating samples of Example 1, Example 2, Comparative Example 1 (without dynamic repair particles), and Comparative Example 3 (without corrosion inhibitor)

[0157] Experimental Steps:

[0158] Sample Preparation:

[0159] Each group of samples was prepared under the same conditions, and the surface was uniformly coated with the protective layer with a thickness of about 20 μm.

[0160] Grouping of samples: Example 1, Example 2, Comparative Example 1, and Comparative Example 3.

[0161] Salt Spray Test:

[0162] The samples were fixed in the salt spray test chamber and exposed to a salt spray environment of 3.5% NaCl solution, with the temperature set to 35°C, and the total test time was 500 hours.

[0163] Every 100 hours, the contact resistance change was measured using an electrochemical workstation.

[0164] Surface Observation:

[0165] After each sampling, the optical microscope was used to observe the distribution and expansion of corrosion spots on the surface of the samples, and the area and density of the corrosion spots were recorded.

[0166] Data record:

[0167] The initial contact resistance, contact resistance at each time node, and corrosion spot situation are recorded and used for comparative analysis.

[0168] Table 2: Comparison of corrosion resistance performance of examples and comparative examples

[0169] Sample Initial contact resistance 100 hour contact resistance 300 hour contact resistance 500 hour contact resistance Example 1 0.12 Ω 0.13 Ω 0.15 Ω 0.18 Ω Example 2 0.14 Ω 0.15 Ω 0.18 Ω 0.21 Ω Comparative Example 1 0.11 Ω 0.19 Ω 0.32 Ω 0.54 Ω Comparative Example 3 0.13 Ω 0.22 Ω 0.39 Ω 0.61 Ω

[0170] The experimental data show that the increase in contact resistance of Example 1 and Example 2 after 500 hours of salt spray test is 0.06Ω and 0.07Ω, respectively, and the corrosion spot area is only 0.5mm 2 and 0.8mm 2 , respectively. In contrast, the contact resistance of Comparative Example 1 and Comparative Example 3 increased significantly, reaching 0.54Ω and 0.61Ω, respectively, and the corrosion spot area increased significantly, indicating that corrosion rapidly expanded on their surfaces. This result indicates that the microcapsule corrosion inhibitor and superhydrophobic particles play a decisive role in the corrosion resistance of the protective layer in long-term salt spray environments.

[0171] From a mechanistic perspective, the improved corrosion resistance of Example 1 and Example 2 can be attributed to two factors: 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, significantly reducing the intrusion rate of corrosive media (such as Cl - ) and delaying the corrosion reaction. Second, the superhydrophobic nanoparticles in the surface layer construct a low-surface-energy micro-nano structure, making it difficult for water droplets and salt spray to adhere to the coating surface, effectively preventing the penetration of corrosive media.

[0172] Comparative Example 1 and Comparative Example 3 lack dynamic repair particles and corrosion inhibitors, respectively, and the protective layer cannot provide effective protection at the crack or metal exposure area, leading to rapid corrosion expansion and significant increase in contact resistance. This indicates that the synergistic effect of corrosion inhibitors and superhydrophobic particles is crucial in the design of the protective layer, while dynamic repair particles, although secondary, also play an auxiliary role in repairing mechanical damage.

[0173] In summary, the present application significantly improves the stability of the protective layer in long-term corrosion environments through the innovative design of microcapsule corrosion inhibitors and superhydrophobic particles. In combination with practical application scenarios, this design is very suitable for application in contact devices such as circuit board contact points, electronic connectors, and other devices that are susceptible to corrosion, extending the service life of the device and reducing maintenance costs. The experiments further verify the rational design of each functional component in the protective layer material and their synergistic effect, demonstrating the creativity and technical value of the present application.

[0174] Experiment 3: Wear resistance test

[0175] Experimental explanation:

[0176] Experimental purpose: Through friction and wear test, the wear resistance of the protective layer under mechanical stress is verified, the effect of different material layers (such as dynamic repair particles and TiO2 nanofibers) on friction loss is analyzed, and the stability of the protective layer under long-term mechanical stress is verified.

[0177] Experimental equipment and materials:

[0178] Friction and wear tester (loading force 10N, friction path length 10mm)

[0179] Four-probe resistance measurement device (for testing contact resistance)

[0180] Example 1, Comparative Example 3 (without corrosion inhibitor), Comparative Example 5 (insufficient fiber calcination temperature) coating sample

[0181] Experimental steps:

[0182] Sample preparation:

[0183] Each group of samples is prepared according to the preparation method of the example or comparative example, and the coating thickness is controlled at 20μm.

[0184] After curing, the sample is fixed on the sample seat of the friction and wear tester.

[0185] Friction test:

[0186] Test conditions: loading force 10N, friction speed 50mm / s, reciprocating friction path length 10mm, total friction cycle number set to 20,000 times.

[0187] During the friction process, the contact resistance of the sample is recorded every 5,000 times, and the wear of the sample surface is observed.

[0188] Thickness measurement:

[0189] After the test, the thickness change of the protective layer after wear is recorded using a thickness measuring instrument, and the thickness loss is calculated.

[0190] Surface observation:

[0191] The surface of the sample after friction is observed using an optical microscope, and the crack propagation and protective layer peeling are recorded.

[0192] Table 3: Comparison of wear resistance performance of examples and comparative examples

[0193] Sample Initial contact resistance Contact resistance after abrasion Thickness loss Crack length Example 1 0.12 Ω 0.15 Ω 2.1 μm 0.5 mm Comparative Example 3 0.13 Ω 0.28 Ω 5.4 μm 1.5 mm Comparative Example 5 0.14 Ω 0.33 Ω 7.8 μm 2.3 mm

[0194] The experimental results show that the contact resistance of Example 1 only increases by 0.03Ω after 20,000 friction cycles, the thickness loss of the protective layer is 2.1μm, the crack length is about 0.5mm, and the surface remains intact as a whole without obvious peeling phenomenon. However, Comparative Example 3 and Comparative Example 5 show significant degradation, with the contact resistance increasing by 0.15Ω and 0.19Ω respectively, the thickness loss of the protective layer being 5.4μm and 7.8μm respectively, and the crack extending to 1.5mm and 2.3mm respectively. These data indicate that the dynamic repair particles and TiO2 nanofibers in the present application play an important role in improving the wear resistance of the protective layer.

[0195] From a mechanism analysis, the dynamic repair particles (Ag + or Zn 2+ ) in Example 1 repair the crack area through electrochemical deposition during the process of crack caused by friction, while the network structure of TiO2 nanofibers provides additional mechanical strength, inhibiting the further expansion of the crack. 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, enabling the protective layer to maintain stable structure and performance during repeated friction.

[0196] In contrast, Comparative Example 3 lacks corrosion inhibitors, and the exposed cracks during the friction process cannot form an anti-corrosion protective film, leading to rapid crack expansion and causing large-scale protective layer peeling. In Comparative Example 5, the insufficient calcination temperature of TiO2 fibers results in poor mechanical properties and interfacial bonding of the fibers, making the protective layer prone to peeling and wear under friction stress, thereby significantly reducing the wear resistance.

[0197] The experimental results further demonstrate that the synergistic design of TiO2 fiber calcination temperature and dynamic repair particles is crucial to the wear resistance of the protective layer. TiO2 fibers provide mechanical support, while dynamic repair particles provide electrical conductivity and local repair capability at the damage site. The combination of the two makes Example 1 exhibit excellent stability in the friction damage test. In combination with the application scenarios, this design is particularly suitable for high-frequency mechanical contact scenarios such as electronic device connectors and automotive electrical interfaces, significantly improving the service life of the contact and reducing the maintenance frequency.

[0198] Experiment 4: Thermal conductivity test

[0199] Experiment Description:

[0200] Purpose of the experiment: To verify the thermal conductivity of the protective layer of the present application in a high-power current or heat source environment, focusing on the role of the underlying thermal conduction design (graphene sheet and hexagonal boron nitride), and proving the innovation of the present application through comparison of surface temperature rise and thermal conductivity.

[0201] Experimental equipment and materials:

[0202] Infrared thermal imager (for recording the sample surface temperature distribution)

[0203] Laser thermal conductivity tester (for testing the thermal conductivity of the sample)

[0204] Constant power heat source (power 5W, bottom temperature 50℃)

[0205] Coating sample of Example 3 (containing graphene and h-BN collaborative design), Comparative Example 4 (without graphene), Comparative Example 6 (without h-BN)

[0206] Experimental steps:

[0207] Sample preparation:

[0208] Prepare the coating samples of Example 3, Comparative Example 4, and Comparative Example 6, ensuring that the sample size is the same, and the coating thickness is about 20μm.

[0209] Fix the sample on the constant power heat source, ensure that the heat source bottom maintains a constant temperature of 50℃, and covers the entire bottom surface of the sample.

[0210] Surface temperature recording:

[0211] Start the heat source and continue heating for 60 minutes, and use the infrared thermal imager to record the sample surface temperature distribution.

[0212] Record the surface temperature every 15 minutes, and mark and count the hot spot area.

[0213] Thermal conductivity test:

[0214] Use the laser thermal conductivity tester to test the thermal conductivity of the sample, and perform 3 repeated tests according to the standard method, and take the average value.

[0215] Data recording and analysis:

[0216] Record the surface maximum temperature, temperature rise, and thermal conductivity of the sample, and perform comparative analysis.

[0217] Table 4: Comparison of thermal conductivity performance of examples and comparative examples

[0218] Sample Initial surface temperature 30 minute surface temperature 60 minute surface temperature Thermal conductivity Example 3 50℃ 53.5℃ 55.2℃ 1.52 W / m-K Comparative Example 4 50℃ 55.8℃ 59.7℃ 0.92 W / m-K Comparative Example 6 50℃ 57℃ 61.3℃ 0.73 W / m-K

[0219] The experimental data shows that the surface temperature rise of Example 3 is only 5.2℃ after 60 minutes of heating, and its thermal conductivity reaches 1.52W / m·K, showing excellent thermal conductivity performance. The surface temperature rise of Comparative Example 4 and Comparative Example 6 reaches 9.7℃ and 11.3℃ 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 graphene and h-BN collaborative design in thermal management.

[0220] From a mechanistic analysis, the excellent thermal conductivity of Example 3 is due to the synergistic effect of graphene sheets and h-BN particles. Graphene has extremely high in-plane thermal conductivity (>2000 W / m·K), which can quickly conduct heat, while h-BN further optimizes the heat transfer path through its two-dimensional layered structure, forming a multidirectional heat conduction network. This design not only improves the overall thermal conductivity, but also significantly reduces the hot spot effect on the surface of the sample, ensuring the stability of the protective layer under high-power current or heat source conditions.

[0221] In contrast, Comparative Example 4 lacks graphene sheets, and its thermal conduction path mainly relies on h-BN, resulting in a decrease in heat transfer efficiency and a higher surface temperature rise; Comparative Example 6 lacks h-BN support and relies solely on graphene for thermal conduction paths that cannot cover the heat flow distribution in the three-dimensional structure, further degrading the heat management capability. Experiments clearly show that a single thermal conduction material is insufficient to meet the heat dissipation needs in high-power scenarios, and the synergistic effect of graphene and h-BN can significantly optimize the thermal conductivity.

[0222] In combination with actual application scenarios, the protective layer design of the present application is particularly suitable for high-power electronic devices or high-temperature environments (such as new energy vehicle electrical interfaces or industrial device terminals), effectively reducing the temperature accumulation on the surface of the device and prolonging the service life of the device. The experimental results not only verify the scientificity of the material level design, but also highlight the significant advantage of the present application in heat management capability, further consolidating the technical innovation and industrial application value of the present application.

[0223] Experiment 5: Comprehensive performance evaluation

[0224] Experimental explanation:

[0225] Experimental purpose: By simulating complex actual application scenarios, the advantages of the protective layer of the present application in wear resistance, corrosion resistance, and comprehensive thermal conductivity performance are verified. 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.

[0226] Experimental equipment and materials:

[0227] Friction and wear tester (loading force 10 N, friction path length 10 mm)

[0228] Salt spray test chamber (3.5% NaCl solution, temperature 35°C)

[0229] Infrared thermal imager (records the temperature distribution on the surface of the sample)

[0230] Coating samples of Example 4 (comprehensive optimization design), Comparative Example 1 (without dynamic repair particles), Comparative Example 3 (without corrosion inhibitor), and Comparative Example 6 (without h-BN)

[0231] Experimental steps:

[0232] Sample preparation:

[0233] Coating samples of Example 4, Comparative Example 1, Comparative Example 3 and Comparative Example 6 were prepared with a controlled coating thickness of 20 pm.

[0234] Each group of samples was labeled and grouped separately for different testing stages.

[0235] Joint experimental procedure:

[0236] Friction test:

[0237] Reciprocating friction test was performed on the samples using a friction and wear tester with a load of 10 N, a friction speed of 50 mm / s, a friction path length of 10 mm, and a test cycle number of 20,000 times. The contact resistance and thickness loss after friction were recorded.

[0238] Salt spray corrosion test:

[0239] Salt spray test was performed on the samples after friction by exposing the samples to a 3.5% NaCl solution at a temperature of 35°C for a test time of 500 hours. The change in contact resistance was recorded and the corrosion state was observed.

[0240] High temperature test:

[0241] The samples were continuously heated for 60 minutes using a constant power heat source (power 5 W, bottom temperature 50°C), and the surface temperature distribution was recorded to test the thermal management performance.

[0242] Data recording and analysis:

[0243] The changes in contact resistance, thickness loss, corrosion spot area, and surface temperature of the samples at each testing stage were recorded, and the comprehensive performance of each sample was analyzed.

[0244] Table 5: Comparative experimental data of the comprehensive performance of examples and comparative examples

[0245] Sample Contact resistance after abrasion Thickness loss Contact resistance after salt spray Corrosion spot area Example 4 0.15 Ω 2.5 μm 0.18 Ω 0.6 mm 2 ]] Comparative Example 1 0.62 Ω 6.2 μm 0.76 Ω 3.8 mm 2 ]] Comparative Example 3 0.48 Ω 5.4 μm 0.68 Ω 4.2 mm 2 ]]> Comparative Example 6 0.52 Ω 7.5 μm 0.8 Ω 4.6 mm 2 ]]

[0246] The experimental data showed that Example 4 exhibited excellent stability and reliability in the comprehensive test: the contact resistance after friction increased by only 0.03 W, the thickness loss was 2.5 pm, the contact resistance after salt spray corrosion was only 0.18 W, the surface corrosion spot area was only 0.6 mm 2 , and the surface temperature rise after 60 minutes of heating was only 5.0°C. In contrast, Comparative Example 1, Comparative Example 3 and Comparative Example 6 all showed significant deterioration in multiple performance.

[0247] From a mechanism analysis, the excellent comprehensive performance of Example 4 is due to the synergistic effect of the multi-layer protection structure. The dynamic repair particles (Ag+ or Zn 2+ )effectively repair the conductive network at the crack site through electrochemical deposition, resulting in minimal changes in contact resistance after rubbing; TiO2nanofibers provide additional mechanical strength, significantly inhibiting the propagation of cracks during rubbing and reducing thickness loss. The microcapsule corrosion inhibitor slowly releases effective antioxidants in a salt spray environment, forming a protective film at the crack site and exposed areas, reducing the formation of corrosion spots, while superhydrophobic particles further prevent the intrusion of moisture and salt spray. In addition, the graphene and h-BN in the bottom layer synergistically build a thermal conductive network, ensuring thermal management performance under high temperature conditions, with the surface temperature rise controlled to a minimum level.

[0248] In contrast, Comparative Example 1 lacks dynamic repair particles, and the conductive network at the crack site cannot be restored after rubbing, 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, resulting in a significant expansion of the corrosion spot area in the salt spray test; Comparative Example 6 lacks h-BN particles, and the thermal conductivity of the protective layer is significantly reduced, with a higher surface temperature rise, indicating insufficient thermal management capability. These results verify the significant advantages of the innovative design of the protective layer of the present application in terms of wear resistance, corrosion resistance, and thermal conductivity.

[0249] This experiment comprehensively simulates the complex stress scenarios in practical applications, and the results clearly show that the present application solves the problem of performance degradation of traditional protective layers under mechanical damage, corrosive environments, and heat source conditions through the design of a multifunctional layered structure. Especially in high-frequency mechanical contact and high-power current application scenarios, such as electronic connectors and automobile electrical interface, Example 4 can significantly improve the reliability and service life of the contact, fully embodying the industrial application value and technical advantages of the present application.

[0250] Although embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made thereto without departing from the principles and spirit of the present application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A contact protection layer for an electrically conductive terminal, characterized in that The protective layer comprises the following layered structure: The surface layer comprises a phosphorus-doped polypyrrole matrix, dynamic repair particles and super-hydrophobic nanoparticles, 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%, the dynamic repair particles are Ag + or Zn 2+ complexes, and the super-hydrophobic nanoparticles are surface-modified silica particles with a particle size range of 50-200 nm; The intermediate layer comprises nanofibers, microcapsule corrosion inhibitors, graphene sheets and a polysiloxane matrix, the nanofibers in the intermediate layer are titanium titanate nanofibers with a diameter of 10-20 nm, the microcapsule corrosion inhibitors are microcapsules encapsulating imidazole compounds or vitamin E with a mass fraction of 2%-5%, the graphene sheets are multilayer graphene with a thickness of 0.34 nm and a mass fraction of 2%-5%, and the polysiloxane matrix has a mass fraction of 70%-80%; The bottom layer comprises hexagonal boron nitride particles and a polyimide matrix, the hexagonal boron nitride particles in the bottom layer have a particle size of 1-2 μm and a mass fraction of 10%-20%, and the polyimide matrix has a mass fraction of 80%-90%.

2. The method of claim 1, wherein the contact protection layer of the electrically conductive terminal is prepared by the method of claim 1, characterized in that, The method comprises the following steps: (1) preparing the surface layer: mixing phosphorus-doped polypyrrole, dynamic repair particles, superhydrophobic nanoparticles and photosensitive active molecules, coating, and curing including ultraviolet light curing and thermal curing; (2) preparing the intermediate layer: mixing nanofibers with microcapsule corrosion inhibitors, graphene sheets and a polysiloxane matrix, coating, and curing at room temperature; (3) preparing the bottom layer: mixing hexagonal boron nitride particles with a polyimide matrix, coating and high-pressure hot pressing.

3. The method of claim 2, wherein the contact protection layer of the electrically conductive terminal is prepared by, The coating process of the surface layer is spin coating process, the spin coating speed is 1000-3000 rpm, the time is 10-30 seconds; the light intensity of ultraviolet light curing is 500-700 mW / cm 2 , the heat curing temperature is 120-150 °C, the time is 1-2 hours.

4. The method of claim 2, wherein the contact protection layer of the conductive terminal is prepared by applying a conductive paste to the surface of the conductive terminal. The nanofibers in 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.

5. The method of claim 2, wherein the contact protection layer of the electrically conductive terminal is prepared by a process comprising: The mixing of the hexagonal boron nitride particles and the polyimide matrix in the bottom layer adopts high-pressure homogenization technology, the homogenization pressure is 30-50 MPa, the hot pressing temperature is 180-200°C, the pressure is 5-10 MPa, and the time is 1-2 hours.

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