A connector surface composite coating and a process for making the same

Abstract

The present application belongs to the technical field of metal material plating, and particularly relates to a connector surface composite coating and a preparation process thereof, which comprises the following steps: adding modified carbon black and sodium molybdate into deionized water, stirring to obtain an corrosion inhibition material, and mixing the corrosion inhibition material with modified zinc oxide to obtain a mixed filler; adding dibutyltin dilaurate and toluene diisocyanate into polypropylene glycol to obtain a core material; adding cetyltrimethylammonium bromide and the mixed filler into a 93-96 wt% ethanol solution, adding the core material to emulsify, adding isophorone diisocyanate solution to stir, and obtaining microcapsules; adding nickel sulfate hexahydrate, nickel chloride hexahydrate, sodium citrate, boric acid, a surface dispersing agent, a sodium hydroxide solution and the microcapsules into deionized water to mix, and obtaining an electroplating solution; placing the connector into the electroplating solution to electroplate, and obtaining a composite coating. The present application can inhibit the expansion of pitting corrosion, and improve the reliability and stability of the connector for long-term use in a marine environment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of metal material plating, and particularly relates to a connector surface composite coating and a preparation process thereof. BACKGROUND

[0002] The connector is a key component in the laser communication system, and its protection performance and reliability are crucial to ensure the normal operation of the system. In order to improve the corrosion resistance of the connector, a coating is usually coated on the surface of the connector to protect the metal substrate of the connector from being damaged. In the prior art, a nickel-containing coating is often coated on the surface of the connector. Nickel can spontaneously form a dense oxide passivation film in the air, which blocks the penetration of corrosive media and improves the service life of the connector. However, when the connector is used at sea, it needs to cope with the salt spray environment rich in chloride ions for a long time. Chloride ions have low hydration energy, high polarization rate and strong coordination ability, which makes chloride ions preferentially adsorb on the surface of the passivation film, replace the hydroxyl or oxygen ions on the surface of the film, destroy the chemical stability of the passivation film, trigger the film degradation process, and cause the passivation film to locally thin or even perforate. Once the passivation film is locally damaged, the exposed metal nickel becomes the anode active area, and the surrounding undamaged part becomes the cathode active area, forming a micro-battery corrosion system containing both cathode and anode areas, i.e. a pitting pit. The self-catalytic corrosion inside the pitting pit continues to occur, and with the passage of time, the pitting pit gradually expands, damaging the coating and corroding the metal substrate of the connector, affecting the normal use of the connector.

[0003] The Chinese invention patent document with publication number CN113981424B discloses a chemical plating Ni-P-graphene composite coating and a preparation method thereof. The mass percentage composition of the composite coating is: phosphorus 8-14%, graphene 0.01-0.5%, and the balance is nickel and unavoidable impurities. In the above-mentioned patent, graphene is uniformly dispersed and co-deposited in the nickel-phosphorus matrix, effectively filling the micro-pores and structural defects of the coating, significantly improving the density and homogeneity of the coating. In terms of protection mechanism, the coating mainly relies on its highly dense microstructure to physically block chloride ions, delaying the penetration of corrosion media such as chloride ions, water molecules and oxygen. It can better inhibit the initiation and expansion of pitting. When the coating is applied to the surface of the connector in the marine salt spray environment, it shows good initial corrosion resistance. However, the coating in the above-mentioned patent is a traditional passive protection type coating and does not have a self-repairing function. Once the coating is damaged and pitting occurs at the damaged site, the coating will not actively release corrosion inhibitors, and it cannot inhibit the further expansion of the pitting pit, ultimately affecting the conductivity of the connector and reducing its reliability and stability in long-term use in marine environments. SUMMARY

[0004] The application provides a connector surface composite coating and a preparation process thereof, which inhibits the expansion of pitting and improves the reliability and stability of the connector in long-term use in a marine environment.

[0005] To solve the above problems, the application provides a connector surface composite coating and a preparation process thereof, which adopts the following technical scheme.

[0006] A preparation process of a connector surface composite coating comprises the following steps:

[0007] S1, adding modified carbon black to deionized water, adding hydrochloric acid solution and sodium molybdate, stirring and compounding, centrifuging, washing, drying to obtain an corrosion inhibition material, mixing with modified zinc oxide to obtain a mixed filler; the modified carbon black is obtained by oxidizing and amino silane modifying the carbon black, and the modified zinc oxide is obtained by amino silane modifying the zinc oxide;

[0008] S2, in an inert atmosphere, adding dibutyltin dilaurate and toluene diisocyanate to anhydrous polypropylene glycol, heating, stirring and reacting, cooling to obtain a core material;

[0009] S3, in an inert atmosphere, adding cetyltrimethylammonium bromide and the mixed filler to a 93-96wt% ethanol solution, dispersing, adding the core material, emulsifying, adding isophorone diisocyanate solution, stirring and reacting, centrifuging, washing, drying to obtain microcapsules;

[0010] S4, adding nickel sulfate hexahydrate, nickel chloride hexahydrate, sodium citrate, boric acid and a surface dispersing agent to deionized water, stirring and mixing, adding sodium hydroxide solution and the microcapsules, stirring and mixing to obtain an electroplating solution;

[0011] S5, placing the connector in the electroplating solution for electroplating, taking out, washing, drying to obtain a composite coating.

[0012] The polyurethane prepolymer with low viscosity and good flowability is prepared by condensation reaction of polypropylene glycol with toluene diisocyanate under catalysis of dibutyl tin dilaurate to obtain the core material; in the preparation process of the microcapsule, cetyltrimethylammonium bromide and the mixed filler are first added to deionized water, then the core material is added and emulsified into oil phase droplets, the cetyltrimethylammonium bromide contains hydrophilic trimethylammonium groups and hydrophobic alkyl groups, in the process of emulsifying the core material into oil phase droplets, the trimethylammonium groups extend to the ethanol solution and the alkyl groups extend to the oil phase droplets, a layer of molecular interface film is formed at the oil-water interface, the mutual polymerization between the oil phase droplets is prevented by electrostatic repulsion and steric hindrance effect, and the stability of the oil phase droplets is maintained, the modified zinc oxide and the modified carbon black in the mixed filler are modified by gamma-aminopropyl triethoxysilane, and hydrophilic amino groups and hydrophobic alkyl chains are introduced on the surface of the modified zinc oxide and the modified carbon black, in the process of emulsifying the core material into oil phase droplets, the mixed filler migrates to the oil-water interface, the hydrophilic region is exposed to the ethanol solution, and the hydrophobic region is embedded in the oil phase droplets, so that the mixed filler is stably adsorbed at the oil-water interface, and a foundation is laid for subsequent construction of the microcapsule shell layer outside the oil phase droplets; then, isophorone diisocyanate solution is added, condensation reaction occurs between the isophorone diisocyanate solution diffused to the oil-water interface and the amino groups on the mixed filler to generate urea bonds, and a polyurea polymer is obtained and deposited in situ on the surface of the oil phase droplets, since the mixed filler contains multiple amino groups, it can be used as a crosslinking node to bridge multiple isophorone diisocyanate molecules, promote the formation of a three-dimensional crosslinked network structure of the polyurea polymer, and as the reaction proceeds, the crosslinked network is continuously densified, and finally a dense polyurea shell layer containing the mixed filler is formed to completely cover the oil phase droplets, the shell layer can realize effective isolation between the core material and the external environment, and maintain the long-term fluidity and chemical stability of the core material.

[0013] The shell layer contains zinc oxide and corrosion inhibition material, the corrosion inhibition material is carbon black compounded with sodium molybdate, when the composite coating is damaged and local pitting occurs, nickel in the composite coating and metals such as iron in the connector metal substrate will undergo anodic reaction, metal dissolution generates metal ions, and the metal ions further hydrolyze to generate hydroxide or oxide and release hydrogen ions, so that the local pH in the pitting pit is significantly reduced to form an acidic environment, the zinc oxide in the microcapsule shell layer reacts with hydrogen ions and gradually dissolves, the shell structure is gradually destroyed, resulting in partial exposure of the modified carbon black compounded with sodium molybdate, the amino groups on the surface of the modified carbon black absorb water molecules in the air to form a micro-water environment, promote the dissolution of sodium molybdate and release molybdate ions, the molybdate ions migrate to the interface of the pitting pit under the driving of the concentration gradient and capillary action and preferentially adsorb on the active sites of nickel, iron and other metals, and are reduced to low-valence molybdenum oxide in the local reducing environment, and then co-deposited with the hydrolysis products of metal ions to form a dense molybdenum-rich composite passivation film in situ, the film has a low carrier concentration and a high electron transfer resistance, increases the charge transfer resistance, inhibits the kinetic process of metal dissolution reaction, reduces the dissolution rate of nickel and iron and other metals, and delays the corrosion expansion.

[0014] With the increase of zinc oxide consumption, the shell layer is locally broken, the core material inside the microcapsule flows out under the action of capillary force and migrates to the surface of the composite passivation film, the remaining isocyanate groups in the polyurethane prepolymer hydrolyze and condense with water molecules in the environment to generate urea bonds, the polyurethane prepolymer is crosslinked through the urea bonds, forms a polyurea polymer and is cured in situ, generates a continuous physical sealing layer on the surface of the composite passivation film, blocks the invasion of corrosive media such as oxygen, water and chloride ions, realizes physical coverage of the pitting area, further inhibits the expansion of the pitting pit, and improves the reliability and stability of the connector in long-term use.

[0015] Further, the modified zinc oxide is prepared by adding zinc oxide into 75-85wt% ethanol solution, ultrasonic dispersion for 30min, adding γ-aminopropyl triethoxysilane hydrolysate under continuous stirring, stirring at 200rpm for 2h, centrifugation at 10000rpm for 10min, washing the precipitate with anhydrous ethanol, freeze-drying at-50℃ for 12h, to obtain the modified zinc oxide; the γ-aminopropyl triethoxysilane hydrolysate is prepared by adding acetic acid solution and γ-aminopropyl triethoxysilane into 75-85wt% ethanol solution, stirring at 200rpm for 30min, to obtain the γ-aminopropyl triethoxysilane hydrolysate.

[0016] Further, the modified carbon black is prepared by adding carbon black into hydrogen peroxide solution, ultrasonic dispersion for 30min, stirring at 300rpm for 6h, deionized water washing, adding into 75-85wt% ethanol solution, adding γ-aminopropyl triethoxysilane hydrolysate, stirring at 300rpm for 6h, centrifugation at 10000rpm for 10min, washing the precipitate with deionized water, to obtain the modified carbon black.

[0017] The carbon black reacts with the hydrogen peroxide solution, increasing the density of hydroxyl groups on the surface of the carbon black; the γ-aminopropyl triethoxysilane hydrolysis generates siloxane containing amino and silicon hydroxyl groups, the carbon black is added into the γ-aminopropyl triethoxysilane hydrolysate, the condensation reaction occurs between the hydroxyl groups on the surface of the carbon black and the silicon hydroxyl groups of the siloxane to generate Si-O-C bonds, the siloxane is grafted on the carbon black, introducing the siloxane containing amino on the carbon black, thus the modified carbon black obtained contains rich amino on the surface, improving the reactivity between the modified carbon black and isophorone diisocyanate, in the process of preparing microcapsules, the modified carbon black can participate in the polymerization reaction through amino as a functional crosslinking point embedded in the polyurea shell layer, which is conducive to the formation of a dense microcapsule shell layer.

[0018] Further, in the step S1, the modified carbon black is added to deionized water, hydrochloric acid solution is added to adjust the pH value to 5, sodium molybdate is added under the condition of 50℃ and 200rpm, and the stirring is continued for 3h. The precipitation is centrifuged at 10000rpm for 10min, washed with deionized water, and freeze-dried at-50℃ for 24h to obtain the corrosion inhibitor.

[0019] The surface of the modified carbon black contains amino groups. After adding the hydrochloric acid solution, the amino groups are protonated to convert into positively charged ammonium ions. The ammonium ions combine with the molybdate ions in the subsequently added sodium molybdate through electrostatic interaction, promoting the compounding of sodium molybdate on the surface of the carbon black.

[0020] Further, in the step S2, dibutyltin dilaurate and toluene diisocyanate are added to anhydrous polypropylene glycol, the temperature is raised to 70℃, and the stirring is continued for 3h at 200rpm. The temperature is cooled to room temperature, dioctyl phthalate is added, and the stirring is continued for 30min at 200rpm. The ethylenediaminetetramethylene phosphonic acid solution is slowly added dropwise under continuous stirring, and the stirring is continued for 10min at 300rpm to obtain the core material. The ethylenediaminetetramethylene phosphonic acid solution is prepared by adding ethylenediaminetetramethylene phosphonic acid to deionized water, stirring and dissolving, and mixing with acetone.

[0021] The dioctyl phthalate is inserted between the polyurethane segments, increasing the intermolecular distance, reducing the intermolecular force, and further reducing the viscosity of the core material, which is conducive to the emulsification of the core material in deionized water to form small and uniform oil phase droplets. After the preparation of the microcapsule shell layer, it can also inhibit the side reaction of isocyanate groups with trace moisture or themselves, prevent the crosslinking and solidification of the core material due to long-term standing, and ensure that the core material remains in a stable liquid state during storage and use. The amino groups in the ethylenediaminetetramethylene phosphonic acid react with part of the isocyanate groups in the prepolymer through polycondensation, connecting the ethylenediaminetetramethylene phosphonic acid with the prepolymer. During the formation of the composite passivation film, the surface may adsorb chloride ions from the environment. After the ethylenediaminetetramethylene phosphonic acid migrates to the surface of the composite passivation film with the prepolymer, the multiple phosphonic acid groups in the ethylenediaminetetramethylene phosphonic acid strongly chelate with the nickel ions on the surface, displacing the adsorbed chloride ions through competitive coordination, forming a stable complex layer. This complex layer not only effectively removes the chloride ions at the interface, but also serves as a functional interface layer, enhancing the interfacial bonding force between the sealing layer and the composite passivation film, effectively blocking the penetration of corrosive media between the sealing layer and the passivation film, and further inhibiting the reactivation and expansion of pitting corrosion.

[0022] Further, in step S3, after adding hexadecyl trimethyl ammonium bromide and mixed fillers into 93-96wt% ethanol solution, stirring at 300 rpm for 30 min, adding core material, ultrasonic emulsification at 700 W for 4-5 min, slowly adding isophorone diisocyanate solution under the condition of 45℃ and 150 rpm, stirring at 200 rpm for 3 h, centrifuging at 8000 rpm for 10 min, washing the precipitate with deionized water, freeze-drying at-50℃ for 30 h, and drying under reduced pressure at 10.3 kPa and 15℃ for 8 h, the microcapsules are obtained; the isophorone diisocyanate solution is prepared by adding isophorone diisocyanate into ethyl acetate and mixing.

[0023] The mixed fillers contain corrosion inhibition materials, the corrosion inhibition materials are modified carbon black compounded with sodium molybdate, and 93-96wt% ethanol solution is used as a medium to disperse the mixed fillers; the water content in the 93-96wt% ethanol solution is small, which can reduce the solubility of sodium molybdate, inhibit the dissolution of sodium molybdate, and ensure that the corrosion inhibition materials compounded in the shell contain more sodium molybdate; the polarity of the 93-96wt% ethanol solution is moderate, which can be used as an aqueous phase for emulsifying the core material, so that the core material is emulsified to form oil phase droplets; since the water molecule concentration of the 93-96wt% ethanol solution is small, the contact opportunity between the isocyanate group and the water molecule is reduced, and the isocyanate group in the core material and the isophorone diisocyanate solution is prevented from being consumed in large quantities in the process of building the shell of the microcapsule.

[0024] Further, in step S4, under the condition of 55℃ and 200 rpm, nickel sulfate hexahydrate, nickel chloride hexahydrate, sodium citrate, boric acid, and a surface dispersant are added into deionized water, stirred at 300 rpm for 30 min, sodium hydroxide solution is added to adjust the pH value to 7, and the microcapsules are added, stirred at 200 rpm for 1.5 h, to obtain an electroplating solution; the surface dispersant is Tween-80.

[0025] Further, in step S5, the temperature of the electroplating solution is increased to 60℃ and kept, the connector is put into the electroplating solution as a cathode, and the connector is electroplated under the condition of a cathode current density of 1.5 A / dm 2 for 1.4-1.6 h, the electroplating solution is stirred at 150 rpm during the electroplating, deionized water is used for washing, and air drying is performed at 60℃ for 3 h, to obtain a composite coating.

[0026] During the electroplating process, nickel ions are reduced and deposited on the cathode surface as metal nickel, at the same time, the microcapsules migrate to the cathode interface under the action of fluid convection, with the continuous deposition of nickel, the microcapsules are continuously mechanically embedded by the newly formed nickel deposition layer, and finally a composite coating with uniformly dispersed microcapsules is formed, and each region of the composite coating has a microcapsule reserve, avoiding the occurrence of local protection loss.

[0027] A connector surface composite coating is prepared by the above-mentioned connector surface composite coating preparation process, and comprises the following raw materials in parts by mass: deionized water 1000-1035 parts, nickel sulfate hexahydrate 180-190 parts, nickel chloride hexahydrate 37-50 parts, sodium citrate 210-220 parts, boric acid 37-49 parts, Tween-80 0.9-1.3 parts, and microcapsules 75-85 parts; the microcapsules comprise the following raw materials in parts by mass: 93-96wt% ethanol solution 250-270 parts, cetyltrimethylammonium bromide 1.2-2.1 parts, mixed fillers 1.5-2.3 parts, core material 100-120 parts, isophorone diisocyanate 5-7 parts, and ethyl acetate 15-21 parts; the core material comprises the following raw materials in parts by mass: anhydrous polypropylene glycol 190-220 parts, dibutyltin dilaurate 0.2-0.4 parts, toluene diisocyanate 28-39 parts, dioctyl phthalate 9.3-12.2 parts, and ethylenediaminetetramethylene phosphonic acid solution 8-11 parts.

[0028] Further, the mixed fillers comprise the following raw materials in parts by mass: modified zinc oxide 5-6 parts and corrosion inhibitor 2-3 parts; the modified zinc oxide comprises the following raw materials in parts by mass: zinc oxide 15-25 parts, 75-85wt% ethanol solution 700-760 parts, and gamma-aminopropyltriethoxysilane hydrolysate 45-55 parts; the corrosion inhibitor comprises the following raw materials in parts by mass: carbon black 6-8 parts, 20-30wt% hydrogen peroxide solution 520-560 parts, 75-85wt% ethanol solution 600-800 parts, gamma-aminopropyltriethoxysilane hydrolysate 50-80 parts, and sodium molybdate 0.6-1.5 parts; the gamma-aminopropyltriethoxysilane hydrolysate comprises the following raw materials in parts by mass: gamma-aminopropyltriethoxysilane 6-12 parts and 75-85wt% ethanol solution 100-130 parts.

[0029] The beneficial effects of the present application are:

[0030] In the microcapsule preparation process, the corrosion inhibitor with amino groups is first added to the deionized water, then the core material is added to the deionized water and emulsified into oil phase droplets, and then the isophorone diisocyanate solution is added; after the isophorone diisocyanate migrates to the oil-water interface, it reacts with the amino groups on the surface of the mixed fillers to form a polyurea polymer and deposit on the surface of the oil phase droplets, finally forming a dense polyurea shell layer containing mixed fillers, which isolates the core material from the external environment and maintains the long-term fluidity and chemical stability of the core material.

[0031] After the connector is put into the electroplating solution for electroplating, a composite coating containing metal nickel and microcapsules is formed on the surface of the connector, after pitting corrosion of the composite coating occurs and causes local pH value to decrease, zinc oxide in the shell layer reacts with hydrogen ions to dissolve, the corrosion inhibitor material is gradually exposed to the air, sodium molybdate releases molybdate ions under the dissolution of water molecules in the air and migrates to the interface of the pitting corrosion pit, a dense and stable composite passivation film is formed at the interface of the pitting corrosion pit, the charge transfer resistance is increased, the dissolution rate of the metal is reduced, and the expansion of corrosion is delayed.

[0032] With the extension of the pitting corrosion time, the dissolution amount of zinc oxide in the microcapsule shell layer in the acidic pitting corrosion environment gradually increases, eventually leading to local rupture of the shell layer, the core material flows out from the inside of the microcapsule and migrates to the surface of the composite passivation film, the remaining isocyanate groups in the polyurethane prepolymer react with water molecules in the environment to form a polyurea polymer and cure in situ, a continuous physical sealing layer is generated on the surface of the composite passivation film, which blocks the invasion of corrosive media such as oxygen, water and chloride ions, further inhibits the expansion of pitting corrosion, and improves the reliability and stability of the connector in long-term use in marine environment. DETAILED DESCRIPTION

[0033] Preparation Example One

[0034] A 1wt% acetic acid solution was added dropwise to 100g of an 80wt% ethanol solution, the pH value was adjusted to 4, 6g of γ-aminopropyl triethoxysilane was added, and stirring was carried out at 200rpm for 30min to obtain a γ-aminopropyl triethoxysilane hydrolysate; 15g of zinc oxide with a particle size of 10nm was added to 750g of an 80wt% ethanol solution, ultrasonic dispersion was carried out at 160W for 30min, 50g of the γ-aminopropyl triethoxysilane hydrolysate was added under stirring at 200rpm, and stirring was continued for 2h, then centrifugation was carried out at 10000rpm for 10min, the supernatant was removed, the precipitate was washed with anhydrous ethanol for 2 times, and freeze-drying was carried out at-50℃ for 12h to obtain modified zinc oxide; 8g of carbon black with an average particle size of 5nm was added to 550g of a 25wt% hydrogen peroxide solution, ultrasonic dispersion was carried out at 160W for 30min, stirring was carried out at 300rpm for 6h, deionized water washing was carried out for 3 times, 700g of an 85wt% ethanol solution was added, 50g of the γ-aminopropyl triethoxysilane hydrolysate was added, stirring was carried out at 300rpm for 6h, centrifugation was carried out at 10000rpm for 10min, the supernatant was removed, the precipitate was washed with deionized water for 2 times, was added to 400g of deionized water, a 2wt% hydrochloric acid solution was added dropwise to adjust the pH value to 5, 0.6g of sodium molybdate was added at 50℃ and 200rpm, stirring was continued for 3h, then centrifugation was carried out at 10000rpm for 10min, the supernatant was removed, the precipitate was washed with deionized water for 2 times, and freeze-drying was carried out at-50℃ for 24h to obtain a corrosion inhibitor material; 5.5g of the modified zinc oxide and 2.5g of the corrosion inhibitor material were uniformly mixed to obtain a mixed filler.

[0035] Preparation Example Two

[0036] To 130 g of 75 wt% ethanol solution, 1 wt% acetic acid solution was added dropwise to adjust the pH value to 4, 12 g of γ-aminopropyl triethoxysilane was added, and stirring was carried out at 200 rpm for 30 min to obtain a γ-aminopropyl triethoxysilane hydrolysate; 25 g of zinc oxide with a particle size of 10 nm was added to 760 g of 75 wt% ethanol solution, and ultrasonic dispersion was carried out at 160 W for 30 min, 55 g of the γ-aminopropyl triethoxysilane hydrolysate was added under stirring at 200 rpm, and stirring was continued for 2 h, then centrifugation was carried out at 10,000 rpm for 10 min, the supernatant was removed, the precipitate was washed with anhydrous ethanol for 2 times, and freeze-drying was carried out at -50 ℃ for 12 h to obtain modified zinc oxide; 6 g of carbon black with an average particle size of 5 nm was added to 520 g of 20 wt% hydrogen peroxide solution, ultrasonic dispersion was carried out at 160 W for 30 min, stirring was carried out at 300 rpm for 6 h, and washing was carried out with deionized water for 3 times, 800 g of 75 wt% ethanol solution was added, 75 g of the γ-aminopropyl triethoxysilane hydrolysate was added, stirring was carried out at 300 rpm for 6 h, centrifugation was carried out at 10,000 rpm for 10 min, the supernatant was removed, the precipitate was washed with deionized water for 2 times, and was added to 400 g of deionized water, 2 wt% hydrochloric acid solution was added dropwise to adjust the pH value to 5, 1.5 g of sodium molybdate was added at 50 ℃ and 200 rpm, and stirring was continued for 3 h, then centrifugation was carried out at 10,000 rpm for 10 min, the supernatant was removed, the precipitate was washed with deionized water for 2 times, and freeze-drying was carried out at -50 ℃ for 24 h to obtain a corrosion inhibitor material; 5 g of the modified zinc oxide and 2 g of the corrosion inhibitor material were mixed uniformly to obtain a mixed filler.

[0037] Preparation Example Three

[0038] To 120 g of 85 wt% ethanol solution, 1 wt% acetic acid solution was added dropwise to adjust the pH value to 4, 10 g of γ-aminopropyl triethoxysilane was added, and stirred at 200 rpm for 30 min to obtain a γ-aminopropyl triethoxysilane hydrolysate; 20 g of zinc oxide with a particle size of 10 nm was added to 700 g of 85 wt% ethanol solution, and dispersed by ultrasonic at 160 W for 30 min, and then 45 g of the γ-aminopropyl triethoxysilane hydrolysate was added under stirring at 200 rpm, and the stirring was continued for 2 h, and then centrifuged at 10,000 rpm for 10 min to remove the supernatant, and the precipitate was washed twice with anhydrous ethanol, and freeze-dried at -50°C for 12 h to obtain modified zinc oxide; 7 g of carbon black with an average particle size of 5 nm was added to 560 g of 30 wt% hydrogen peroxide solution, and dispersed by ultrasonic at 160 W for 30 min, and stirred at 300 rpm for 6 h, and washed with deionized water for 3 times, and then added to 600 g of 80 wt% ethanol solution, and 80 g of the γ-aminopropyl triethoxysilane hydrolysate was added, and stirred at 300 rpm for 6 h, and then centrifuged at 10,000 rpm for 10 min to remove the supernatant, and the precipitate was washed twice with deionized water, and then added to 400 g of deionized water, and 2 wt% hydrochloric acid solution was added dropwise to adjust the pH value to 5, and then 1.2 g of sodium molybdate was added at 50°C and 200 rpm, and the stirring was continued for 3 h, and then centrifuged at 10,000 rpm for 10 min to remove the supernatant, and the precipitate was washed twice with deionized water, and freeze-dried at -50°C for 24 h to obtain a corrosion inhibitor material; 6 g of the modified zinc oxide and 3 g of the corrosion inhibitor material were mixed uniformly to obtain a mixed filler.

[0039] Example One

[0040] To 3.9 g of deionized water, 0.6 g of ethylenediaminetetramethylene phosphonic acid was added, stirred at 300 rpm for 10 min, 5.5 g of acetone was added and mixed to obtain an ethylenediaminetetramethylene phosphonic acid solution; 6 g of isophorone diisocyanate was added to 18 g of ethyl acetate and mixed to obtain an isophorone diisocyanate solution; under a nitrogen atmosphere, 0.3 g of dibutyl tin dilaurate, 30 g of toluene diisocyanate were sequentially added to 200 g of anhydrous polypropylene glycol with a molecular weight of 2000 g / mol, the temperature was raised to 70°C, and stirred at 200 rpm for 3 h, and then cooled to room temperature, 10.5 g of dioctyl phthalate was added, stirred at 200 rpm for 30 min, 10 g of ethylenediaminetetramethylene phosphonic acid solution was added at a speed of 1 g / min under the condition of stirring at 300 rpm, and after all the addition, stirring was continued for 10 min to obtain a core material; under a nitrogen atmosphere, 1.8 g of cetyltrimethylammonium bromide and 1.5 g of mixed filler were added to 260 g of 93 wt% ethanol solution, stirred at 300 rpm for 30 min, then 120 g of the core material was added, and ultrasonic emulsification was performed at 700 W for 4 min, 24 g of isophorone diisocyanate solution was slowly added at a speed of 2 g / min under the condition of 45°C and 150 rpm, after all the addition, stirring was performed at 200 rpm for 3 h, then centrifugation was performed at 8000 rpm for 10 min, the supernatant was removed, the precipitate was washed with deionized water for 2 times, freeze-dried at -50°C for 30 h, and dried under reduced pressure at 10.3 kPa and 15°C for 8 h to obtain microcapsules.

[0041] Under the condition of 55°C and 200 rpm, 180 g of nickel sulfate hexahydrate, 45 g of nickel chloride hexahydrate, 210 g of sodium citrate, 49 g of boric acid, and 1 g of Tween-80 were sequentially added to 1000 g of deionized water, stirred at 300 rpm for 30 min, 1 wt% sodium hydroxide solution was added dropwise to adjust the pH value to 7, 75 g of microcapsules were added, and stirred at 200 rpm for 1.5 h to obtain an electroplating solution, the temperature of the electroplating solution was raised to 60°C and kept, the connector was immersed into the electroplating solution, the connector was used as the cathode, a nickel plate was used as the anode, and electroplating was performed at a cathode current density of 1.5 A / dm 2 Under the condition of 55°C and 200 rpm, 180 g of nickel sulfate hexahydrate, 45 g of nickel chloride hexahydrate, 210 g of sodium citrate, 49 g of boric acid, and 1 g of Tween-80 were sequentially added to 1000 g of deionized water, stirred at 300 rpm for 30 min, 1 wt% sodium hydroxide solution was added dropwise to adjust the pH value to 7, 75 g of microcapsules were added, and stirred at 200 rpm for 1.5 h to obtain an electroplating solution, the temperature of the electroplating solution was raised to 60°C and kept, the connector was immersed into the electroplating solution, the connector was used as the cathode, a nickel plate was used as the anode, and electroplating was performed at a cathode current density of 1.5 A / dm

[0042] The mixed filler used in this example was prepared according to Preparation Example 1.

[0043] Example 2

[0044] To 3.1 g of deionized water, 0.5 g of ethylenediaminetetramethylene phosphonic acid was added, stirred at 300 rpm for 10 min, 4.4 g of acetone was added and mixed to obtain an ethylenediaminetetramethylene phosphonic acid solution; 5 g of isophorone diisocyanate was added to 15 g of ethyl acetate and mixed to obtain an isophorone diisocyanate solution; under a nitrogen atmosphere, 0.2 g of dibutyl tin dilaurate, 28 g of toluene diisocyanate were sequentially added to 190 g of anhydrous polypropylene glycol with a molecular weight of 2000 g / mol, the temperature was raised to 70°C, and stirred at 200 rpm for 3 h, and then cooled to room temperature, 9.3 g of dioctyl phthalate was added, stirred at 200 rpm for 30 min, 8 g of ethylenediaminetetramethylene phosphonic acid solution was added at a speed of 1 g / min under the condition of stirring at 300 rpm, and after all the addition, stirring was continued for 10 min to obtain a core material; under a nitrogen atmosphere, 2.1 g of cetyltrimethylammonium bromide and 1.7 g of mixed filler were added to 250 g of 95 wt% ethanol solution, stirred at 300 rpm for 30 min, then 115 g of the core material was added, and ultrasonic emulsification was performed at 700 W for 5 min, 20 g of isophorone diisocyanate solution was slowly added at a speed of 2 g / min under the condition of 45°C and 150 rpm, after all the addition, stirring was performed at 200 rpm for 3 h, then centrifugation was performed at 8000 rpm for 10 min, the supernatant was removed, the precipitate was washed with deionized water for 2 times, freeze-dried at -50°C for 30 h, and dried under reduced pressure at 10.3 kPa and 15°C for 8 h to obtain microcapsules.

[0045] Under the condition of 55°C and 200 rpm, 185 g of nickel sulfate hexahydrate, 50 g of nickel chloride hexahydrate, 215 g of sodium citrate, 45 g of boric acid, and 1.1 g of Tween-80 were sequentially added to 1022 g of deionized water, stirred at 300 rpm for 30 min, 1 wt% sodium hydroxide solution was added dropwise to adjust the pH value to 7, 80 g of microcapsules were added, and stirred at 200 rpm for 1.5 h to obtain an electroplating solution, the temperature of the electroplating solution was raised to 60°C and kept, the connector was immersed into the electroplating solution, the connector was used as the cathode, a nickel plate was used as the anode, and electroplating was performed at a cathode current density of 1.5 A / dm 2 Under the condition of 55°C and 200 rpm, 185 g of nickel sulfate hexahydrate, 50 g of nickel chloride hexahydrate, 215 g of sodium citrate, 45 g of boric acid, and 1.1 g of Tween-80 were sequentially added to 1022 g of deionized water, stirred at 300 rpm for 30 min, 1 wt% sodium hydroxide solution was added dropwise to adjust the pH value to 7, 80 g of microcapsules were added, and stirred at 200 rpm for 1.5 h to obtain an electroplating solution, the temperature of the electroplating solution was raised to 60°C and kept, the connector was immersed into the electroplating solution, the connector was used as the cathode, a nickel plate was used as the anode, and electroplating was performed at a cathode current density of 1.5 A / dm

[0046] The mixed filler used in this example was prepared according to Preparation Example One.

[0047] Example Three

[0048] To 3.5 g of deionized water, 0.5 g of ethylenediaminetetramethylene phosphonic acid was added, stirred at 300 rpm for 10 min, 4.9 g of acetone was added and mixed to obtain an ethylenediaminetetramethylene phosphonic acid solution; 6.5 g of isophorone diisocyanate was added to 19.5 g of ethyl acetate and mixed to obtain an isophorone diisocyanate solution; under a nitrogen atmosphere, 0.3 g of dibutyl tin dilaurate, 35 g of toluene diisocyanate were sequentially added to 210 g of anhydrous polypropylene glycol with a molecular weight of 2000 g / mol, the temperature was raised to 70°C, and stirred at 200 rpm for 3 h, and then cooled to room temperature, 11 g of dioctyl phthalate was added, stirred at 200 rpm for 30 min, 9 g of ethylenediaminetetramethylene phosphonic acid solution was added at a speed of 1 g / min under the condition of stirring at 300 rpm, and after all the addition, stirring was continued for 10 min to obtain a core material; under a nitrogen atmosphere, 1.2 g of cetyltrimethylammonium bromide and 2.3 g of mixed filler were added to 270 g of 96 wt% ethanol solution, stirred at 300 rpm for 30 min, then 100 g of the core material was added, and ultrasonic emulsification was performed at 700 W for 4.5 min, 26 g of isophorone diisocyanate solution was slowly added at a speed of 2 g / min under the condition of 45°C and 150 rpm, after all the addition, stirring was performed at 200 rpm for 3 h, then centrifugation was performed at 8000 rpm for 10 min, the supernatant was removed, the precipitate was washed with deionized water for 2 times, freeze-dried at -50°C for 30 h, and dried under reduced pressure at 10.3 kPa and 15°C for 8 h to obtain microcapsules.

[0049] Under the condition of 55°C and 200 rpm, 190 g of nickel sulfate hexahydrate, 40 g of nickel chloride hexahydrate, 220 g of sodium citrate, 37 g of boric acid, and 0.9 g of Tween-80 were sequentially added to 1113 g of deionized water, stirred at 300 rpm for 30 min, 1 wt% sodium hydroxide solution was added dropwise to adjust the pH value to 7, 79 g of microcapsules were added, stirred at 200 rpm for 1.5 h to obtain a plating solution, the temperature of the plating solution was raised to 60°C and kept, the connector was immersed into the plating solution, the connector was used as the cathode, a nickel plate was used as the anode, and plating was performed at a cathode current density of 1.5 A / dm 2 Under the condition of 55°C and 200 rpm, 190 g of nickel sulfate hexahydrate, 40 g of nickel chloride hexahydrate, 220 g of sodium citrate, 37 g of boric acid, and 0.9 g of Tween-80 were sequentially added to 1113 g of deionized water, stirred at 300 rpm for 30 min, 1 wt% sodium hydroxide solution was added dropwise to adjust the pH value to 7, 79 g of microcapsules were added, stirred at 200 rpm for 1.5 h to obtain a plating solution, the temperature of the plating solution was raised to 60°C and kept, the connector was immersed into the plating solution, the connector was used as the cathode, a nickel plate was used as the anode, and plating was performed at a cathode current density of 1.5 A / dm

[0050] The mixed filler used in this example was prepared according to Preparation Example Two.

[0051] Example Four

[0052] To 4.3 g of deionized water, 0.6 g of ethylenediaminetetramethylene phosphonic acid was added, stirred at 300 rpm for 10 min, 6 g of acetone was added and mixed to obtain an ethylenediaminetetramethylene phosphonic acid solution; 7 g of isophorone diisocyanate was added to 21 g of ethyl acetate and mixed to obtain an isophorone diisocyanate solution; under a nitrogen atmosphere, 0.4 g of dibutyl tin dilaurate, 39 g of toluene diisocyanate were sequentially added to 220 g of anhydrous polypropylene glycol with a molecular weight of 2000 g / mol, the temperature was raised to 70°C, and stirred at 200 rpm for 3 h, and then cooled to room temperature. 12.2 g of dioctyl phthalate was added and stirred at 200 rpm for 30 min. 11 g of ethylenediaminetetramethylene phosphonic acid solution was added at a rate of 1 g / min under stirring at 300 rpm, and after all the solution was added, stirring was continued for 10 min to obtain a core material; under a nitrogen atmosphere, 1.6 g of cetyltrimethylammonium bromide and 2.1 g of mixed filler were added to 265 g of 95 wt% ethanol solution, stirred at 300 rpm for 30 min, and then 108 g of the core material was added. The mixture was ultrasonically emulsified at 700 W for 4 min, and then 28 g of isophorone diisocyanate solution was slowly added at a rate of 2 g / min under the condition of 45°C and 150 rpm. After all the solution was added, the mixture was stirred at 200 rpm for 3 h, and then centrifuged at 8000 rpm for 10 min to remove the supernatant. The precipitate was washed with deionized water twice, freeze-dried at -50°C for 30 h, and then dried under reduced pressure at 10.3 kPa and 15°C for 8 h to obtain microcapsules.

[0053] Under the condition of 55°C and 200 rpm, 183 g of nickel sulfate hexahydrate, 37 g of nickel chloride hexahydrate, 217 g of sodium citrate, 42 g of boric acid, and 1.3 g of Tween-80 were sequentially added to 1035 g of deionized water, stirred at 300 rpm for 30 min, and then 1 wt% sodium hydroxide solution was added to adjust the pH value to 7. 85 g of the microcapsules were added and stirred at 200 rpm for 1.5 h to obtain an electroplating solution. The temperature of the electroplating solution was raised to 60°C and kept at this temperature. The connector was immersed in the electroplating solution, with the connector as the cathode and a nickel plate as the anode. The electroplating was carried out at a cathode current density of 1.5 A / dm 2 Under the condition of 55°C and 200 rpm, 183 g of nickel sulfate hexahydrate, 37 g of nickel chloride hexahydrate, 217 g of sodium citrate, 42 g of boric acid, and 1.3 g of Tween-80 were sequentially added to 1035 g of deionized water, stirred at 300 rpm for 30 min, and then 1 wt% sodium hydroxide solution was added to adjust the pH value to 7. 85 g of the microcapsules were added and stirred at 200 rpm for 1.5 h to obtain an electroplating solution. The temperature of the electroplating solution was raised to 60°C and kept at this temperature. The connector was immersed in the electroplating solution, with the connector as the cathode and a nickel plate as the anode. The electroplating was carried out at a cathode current density of 1.5 A / dm

[0054] The mixed filler used in this example was prepared according to Preparation Example Two.

[0055] Example Five

[0056] To 21 g of ethyl acetate, 7 g of isophorone diisocyanate was added and mixed to obtain isophorone diisocyanate solution; under nitrogen atmosphere, to 220 g of anhydrous polypropylene glycol with molecular weight of 2000 g / mol, 0.4 g of dibutyl tin dilaurate, 39 g of toluene diisocyanate were added in sequence, the temperature was raised to 70 °C, 200 rpm stirring was carried out for 3 h, and then the temperature was cooled to room temperature, 12 g of dioctyl phthalate was added, 200 rpm stirring was carried out for 30 min to obtain the core material; under nitrogen atmosphere, to 265 g of 95 wt% ethanol solution, 1.6 g of cetyl trimethyl ammonium bromide and 2.1 g of mixed filler were added, 300 rpm stirring was carried out for 30 min, then 108 g of the core material was added, 700 W ultrasonic emulsification was carried out for 4 min, under the condition of 45 °C and 150 rpm, 28 g of isophorone diisocyanate solution was slowly added at a speed of 2 g / min, after all the solution was added, 200 rpm stirring was carried out for 3 h, then 8000 rpm centrifugation was carried out for 10 min, the supernatant was removed, the precipitate was washed with deionized water for 2 times, -50 °C freeze drying was carried out for 30 h, and 10.3 kPa, 15 °C reduced pressure drying was carried out for 8 h to obtain the microcapsule.

[0057] Under the condition of 55 °C and 200 rpm, to 1035 g of deionized water, 183 g of nickel sulfate hexahydrate, 37 g of nickel chloride hexahydrate, 217 g of sodium citrate, 42 g of boric acid, 1.3 g of Tween-80 were added in sequence, 300 rpm stirring was carried out for 30 min, 1 wt% sodium hydroxide solution was added dropwise to adjust the pH value to 7, 85 g of the microcapsule was added, 200 rpm stirring was carried out for 1.5 h to obtain the electroplating solution, the temperature of the electroplating solution was raised to 60 °C and kept, the connector was immersed into the electroplating solution, the connector was used as the cathode, a nickel plate was used as the anode, and the electroplating was carried out under the condition of 1.5 A / dm 2

[0058] The mixed filler used in this example was prepared by the preparation example three.

[0059] Example six

[0060] ​To 4.3 g of deionized water, 0.6 g of ethylenediaminetetramethylene phosphonic acid was added, stirred at 300 rpm for 10 min, 6 g of acetone was added and mixed to obtain an ethylenediaminetetramethylene phosphonic acid solution; 21 g of ethyl acetate was added to 7 g of isophorone diisocyanate and mixed to obtain an isophorone diisocyanate solution; under a nitrogen atmosphere, 0.4 g of dibutyltin dilaurate, 39 g of toluene diisocyanate were sequentially added to 220 g of anhydrous polypropylene glycol with a molecular weight of 2000 g / mol, the temperature was raised to 70°C, and stirred at 200 rpm for 3 h, and then cooled to room temperature. Under the condition of stirring at 300 rpm, 11 g of ethylenediaminetetramethylene phosphonic acid solution was added at a speed of 1 g / min, and after all the addition, the stirring was continued for 10 min to obtain the core material; under a nitrogen atmosphere, 1.6 g of cetyltrimethylammonium bromide and 2.1 g of mixed filler were added to 265 g of 95 wt% ethanol solution, stirred at 300 rpm for 30 min, then 108 g of the core material was added, and 28 g of isophorone diisocyanate solution was slowly added at a speed of 2 g / min under the condition of 45°C and 150 rpm. After all the addition, the stirring was continued at 200 rpm for 3 h, and then centrifuged at 8000 rpm for 10 min to remove the supernatant. The precipitate was washed with deionized water for 2 times, freeze-dried at -50°C for 30 h, and dried under reduced pressure at 10.3 kPa and 15°C for 8 h to obtain the microcapsule.

[0061] Under the condition of 55°C and 200 rpm, 183 g of nickel sulfate hexahydrate, 37 g of nickel chloride hexahydrate, 217 g of sodium citrate, 42 g of boric acid, and 1.3 g of Tween-80 were sequentially added to 1035 g of deionized water, stirred at 300 rpm for 30 min, and then 1 wt% sodium hydroxide solution was added to adjust the pH value to 7. 85 g of the microcapsule was added and stirred at 200 rpm for 1.5 h to obtain the electroplating solution. The temperature of the electroplating solution was raised to 60°C and kept constant. The connector was immersed in the electroplating solution, with the connector as the cathode and a nickel plate as the anode. The electroplating was carried out at a cathode current density of 1.5 A / dm 2 Under the condition of 55°C and 200 rpm, 183 g of nickel sulfate hexahydrate, 37 g of nickel chloride hexahydrate, 217 g of sodium citrate, 42 g of boric acid, and 1.3 g of Tween-80 were sequentially added to 1035 g of deionized water, stirred at 300 rpm for 30 min, and then 1 wt% sodium hydroxide solution was added to adjust the pH value to 7. 85 g of the microcapsule was added and stirred at 200 rpm for 1.5 h to obtain the electroplating solution. The temperature of the electroplating solution was raised to 60°C and kept constant. The connector was immersed in the electroplating solution, with the connector as the cathode and a nickel plate as the anode. The electroplating was carried out at a cathode current density of 1.5 A / dm

[0062] The mixed filler used in this example was prepared according to Preparation Example Three.

[0063] The present application also provides a comparative example and conducts relevant tests.

[0064] Comparative Example One

[0065] The difference between this comparative example and Example Four is that no mixed filler was added during the preparation of the core material, and the remaining operation steps and conditions were the same as those of Example Four to obtain the composite coating.

[0066] Comparative Example Two

[0067] The difference between this comparative example and Example Four is that the carbon black is not modified by oxidation and aminosilane, and the zinc oxide is not modified by aminosilane, and the remaining operation steps and conditions are the same as those of Example Four, to obtain a composite coating.

[0068] Comparative Example Three

[0069] At 55°C and 200 rpm, 1035 g of deionized water was sequentially added with 183 g of nickel sulfate hexahydrate, 37 g of nickel chloride hexahydrate, 217 g of sodium citrate, 42 g of boric acid, and 1.3 g of Tween-80, and stirred at 300 rpm for 30 min. A 1 wt% sodium hydroxide solution was added dropwise to adjust the pH value to 7, and stirred at 200 rpm for 1.5 h to obtain an electroplating solution. The temperature of the electroplating solution was increased to 60°C and the connector was immersed in the electroplating solution with the connector as the cathode and a nickel plate as the anode. The electroplating was performed at a cathode current density of 1.5 A / dm 2 for 1.6 h, during which the electroplating solution was continuously stirred at 150 rpm. After removal, the connector was washed with deionized water and air-dried at 60°C for 3 h to obtain a composite coating.

[0070] Corrosion resistance test

[0071] Each of the composite coating samples prepared in Examples One to Six and Comparative Examples One to Three was subjected to a scratch test, the scratch cut penetrated the composite coating and went into the metal substrate of the connector. Then each of the composite coating samples was placed in a salt spray chamber and exposed to a salt spray environment generated by a 5 wt% sodium chloride solution, and the temperature of the salt spray environment was maintained at 35°C. According to the ISO 4628-3 standard, the ratio of the rusted area in the scratch area to the total surface area of the scratch area was recorded on the first day, the fifth day, the tenth day, the twentieth day, and the thirtieth day of exposure of each sample, as shown in Table 1.

[0072] Table 1

[0073]

[0074] Long-term stability test

[0075] Each of the samples prepared in Examples One to Six and Comparative Examples One to Six was placed in a salt spray chamber for storage, and subjected to a scratch test on the tenth day, the fiftieth day, the one hundred and twentieth day, and the two hundred and thirtieth day of storage, respectively. Then each of the samples was placed in a salt spray chamber, and the ratio of the rusted area in the scratch area to the total surface area of the scratch area was recorded on the fifteenth day after the scratch test, as shown in Table 2.

[0076] Table 2

[0077]

[0078] From the analysis of Table 1 and Table 2, it can be seen that the corrosion area of Examples 1 to 4 and Example 6 is slightly larger than that of Example 5 at the 30th day of the cross, which proves that the addition of the ethylenediamine tetramethylene phosphonic acid solution in the core material can inhibit the reactivation and expansion of the pitting area, and improve the corrosion resistance of the composite coating; compared with Example 6, the composite coating prepared in Examples 1 to 5 still shows good ability to inhibit the spread of pitting after standing for 230 days, which proves that the addition of dioctyl phthalate in the core material can maintain the good flow state of the core material, so that the composite coating has long-term stable ability to inhibit pitting.

[0079] Compared with Example 6, Comparative Example 1 and Comparative Example 3 do not contain microcapsules and have almost no ability to inhibit the spread of pitting, which shows that the addition of microcapsules containing mixed fillers gives the composite material the ability to respond to damage, can build a protective barrier at the pitting site, inhibit the spread of pitting, and protect the long-term use stability of the connector substrate; Comparative Example 2 contains microcapsules and can inhibit the spread of pitting, but the response speed to damage is slow, which shows that the amino silane modification of zinc oxide and carbon black increases the content of mixed fillers in the shell layer of the microcapsules, and improves the response speed of the composite material to pitting.

Claims

1. A process for the preparation of a connector surface composite coating, characterized in that, It comprises the following steps: S1, adding modified carbon black to deionized water, adding hydrochloric acid solution and sodium molybdate, stirring and compounding, centrifuging, washing, drying to obtain corrosion inhibitor material, mixing with modified zinc oxide to obtain mixed filler; the modified carbon black is obtained by oxidizing and modifying the carbon black with amino silane, and the modified zinc oxide is obtained by modifying the zinc oxide with amino silane; The modified zinc oxide is prepared by adding zinc oxide to a 75-85wt% ethanol solution, ultrasonic dispersion for 30min, adding a gamma-aminopropyl triethoxysilane hydrolysate under continuous stirring, stirring at 200rpm for 2h, centrifuging at 10000rpm for 10min, washing the precipitate with anhydrous ethanol, and freeze-drying at-50℃ for 12h to obtain the modified zinc oxide; the gamma-aminopropyl triethoxysilane hydrolysate is prepared by adding acetic acid solution and gamma-aminopropyl triethoxysilane to a 75-85wt% ethanol solution, stirring at 200rpm for 30min to obtain the gamma-aminopropyl triethoxysilane hydrolysate; the modified carbon black is prepared by adding carbon black to a hydrogen peroxide solution, ultrasonic dispersion for 30min, stirring at 300rpm for 6h, washing with deionized water, adding a 75-85wt% ethanol solution, adding a gamma-aminopropyl triethoxysilane hydrolysate, stirring at 300rpm for 6h, centrifuging at 10000rpm for 10min, and washing the precipitate with deionized water to obtain the modified carbon black; S2, in an inert atmosphere, adding dibutyltin dilaurate and toluene diisocyanate to anhydrous polypropylene glycol, warming, stirring and reacting, and cooling to obtain the core material; S3, in an inert atmosphere, adding cetyltrimethylammonium bromide and the mixed filler to a 93-96wt% ethanol solution, dispersing, adding the core material, emulsifying, adding isophorone diisocyanate solution, stirring and reacting, and centrifuging, washing, and drying to obtain the microcapsule; S4, adding nickel sulfate hexahydrate, nickel chloride hexahydrate, sodium citrate, boric acid, and a surface dispersant to deionized water, stirring and mixing, adding sodium hydroxide solution and the microcapsule, stirring and mixing, and obtaining the electroplating solution; S5, placing the connector in the electroplating solution for electroplating, taking it out, washing, and drying to obtain the composite coating.

2. The process for preparing a connector surface composite coating according to claim 1, characterized in that, In step S1, modified carbon black is added to deionized water, hydrochloric acid solution is added to adjust the pH value to 5, sodium molybdate is added at 50℃ and 200rpm, stirring is continued for 3h, centrifuging is performed at 10000rpm for 10min, the precipitate is washed with deionized water, and freeze-drying is performed at-50℃ for 24h to obtain the corrosion inhibitor material.

3. The process for preparing a connector surface composite coating according to claim 2, characterized in that, In step S2, dibutyltin dilaurate and toluene diisocyanate are added to anhydrous polypropylene glycol, the temperature is raised to 70℃, stirring is performed at 200rpm for 3h, the temperature is cooled to room temperature, dioctyl phthalate is added, stirring is performed at 200rpm for 30min, ethylenediaminetetramethylene phosphonic acid solution is slowly added dropwise under continuous stirring, and stirring is performed at 300rpm for 10min to obtain the core material; the ethylenediaminetetramethylene phosphonic acid solution is prepared by adding ethylenediaminetetramethylene phosphonic acid to deionized water, stirring and dissolving, and adding acetone to mix uniformly.

4. The process for preparing a connector surface composite coating according to claim 3, characterized in that, In step S3, after adding cetyltrimethylammonium bromide and mixed fillers into 93-96wt% ethanol solution, stirring at 300rpm for 30min, adding core material, ultrasonic emulsification at 700W for 4-5min, slowly dropping isophorone diisocyanate solution under the condition of 45℃ and 150rpm, stirring at 200rpm for 3h, centrifuging at 8000rpm for 10min, washing the precipitate with deionized water, freeze-drying at-50℃ for 30h, and drying under reduced pressure at 10.3kPa and 15℃ for 8h, the microcapsule is obtained; the isophorone diisocyanate solution is prepared by adding isophorone diisocyanate into ethyl acetate and mixing.

5. The process for preparing a connector surface composite coating according to claim 4, characterized in that In step S4, under the condition of 55℃ and 200rpm, adding nickel sulfate hexahydrate, nickel chloride hexahydrate, sodium citrate, boric acid and surface dispersant into deionized water, stirring at 300rpm for 30min, adding sodium hydroxide solution to adjust pH value to 7, adding microcapsule, and stirring at 200rpm for 1.5h to obtain the electroplating solution; the surface dispersant is Tween-80.

6. The process for preparing a connector surface composite coating according to claim 5, characterized in that In the step S5, the temperature of the electroplating solution is raised to 60°C and the connector is put into the electroplating solution as a cathode. The cathode current density is 1.5 A / dm 2 and the electroplating is carried out for 1.4-1.6 h under the condition that the electroplating solution is stirred at 150 rpm. After the electroplating, the connector is washed with deionized water and is dried by blowing air at 60°C for 3 h to obtain a composite coating.

7. A connector surface composite coating prepared by the process of any one of claims 3-6, characterized in that, The raw materials include the following components by mass: deionized water 1000-1035 parts, nickel sulfate hexahydrate 180-190 parts, nickel chloride hexahydrate 37-50 parts, sodium citrate 210-220 parts, boric acid 37-49 parts, Tween-80 0.9-1.3 parts, and microcapsule 75-85 parts; the microcapsule includes the following components by mass: 93-96wt% ethanol solution 250-270 parts, cetyltrimethylammonium bromide 1.2-2.1 parts, mixed fillers 1.5-2.3 parts, core material 100-120 parts, isophorone diisocyanate 5-7 parts, and ethyl acetate 15-21 parts; the core material includes the following components by mass: anhydrous polypropylene glycol 190-220 parts, dibutyltin dilaurate 0.2-0.4 parts, toluene diisocyanate 28-39 parts, dioctyl phthalate 9.3-12.2 parts, and ethylenediaminetetramethylene phosphonic acid solution 8-11 parts.

8. A connector surface composite coating according to claim 7, wherein The mixed fillers include the following components by mass: modified zinc oxide 5-6 parts and corrosion inhibitor 2-3 parts; The modified zinc oxide includes the following components by mass: zinc oxide 15-25 parts, 75-85wt% ethanol solution 700-760 parts, and γ-aminopropyl triethoxysilane hydrolysate 45-55 parts; the corrosion inhibitor includes the following components by mass: carbon black 6-8 parts, 20-30wt% hydrogen peroxide solution 520-560 parts, 75-85wt% ethanol solution 600-800 parts, γ-aminopropyl triethoxysilane hydrolysate 50-80 parts, and sodium molybdate 0.6-1.5 parts; the γ-aminopropyl triethoxysilane hydrolysate includes the following components by mass: γ-aminopropyl triethoxysilane 6-12 parts and 75-85wt% ethanol solution 100-130 parts.

Images