Corrosion resistant coating for copper-nickel bushings and method of making same

Abstract

The application discloses a kind of corrosion-resistant layer of copper nickel sleeve and its preparation method, including corrosion-resistant outer layer and corrosion-resistant inner layer.The application adopts the double-layer corrosion-resistant design of corrosion-resistant inner layer and corrosion-resistant outer layer, can effectively carry out double corrosion-resistant treatment to copper nickel sleeve outside, even if corrosion-resistant outer layer is corroded after long time use, corrosion-resistant inner layer can still carry out corrosion-resistant protection treatment to copper nickel sleeve, can effectively guarantee the long-term use of copper nickel sleeve in high corrosion environment, can effectively guarantee the service life of copper nickel sleeve;Thioacetamide and benzotriazole cooperate together to form corrosion-resistant inner layer on the surface of copper nickel sleeve, can effectively improve the surface hydrophobicity of the surface of corrosion-resistant inner layer of copper nickel sleeve, in turn reduce the residence time of corrosive liquid on copper nickel sleeve, in turn effectively improve corrosion resistance;Uniformly dispersed nano zirconium oxide enhances the physical shielding and corrosion resistance of corrosion-resistant outer layer.

Description

Technical Field

[0001] This invention relates to the field of copper-nickel bushing technology, and more specifically, to a corrosion-resistant layer for copper-nickel bushing and its preparation method. Background Technology

[0002] Copper-nickel alloy pipe is an alloy pipe with copper and nickel as the main components. Copper-nickel alloy has good corrosion resistance and electrical conductivity, and is often used in electronic equipment, cables, chemical industry and marine engineering.

[0003] Patent (CN117626051A) discloses a copper-nickel alloy and its preparation method, relating to the field of alloy materials technology. The main technical solution is as follows: a copper-nickel alloy, by weight percentage, comprising the following chemical composition: Ni: 10-30 wt%; Fe: 0-1.8 wt%; Mn: 0-1.0 wt%; microalloying elements: 0.05-0.2 wt%; impurity elements: <0.5 wt%; balance Cu; wherein the microalloying elements include noble metal elements. This invention mainly utilizes the synergistic effect of microalloying elements in accelerating the cathodic and anodic reactions of the copper-nickel alloy in corrosive salt solutions and promoting the nucleation of heterogeneous precipitation, thereby significantly improving the protective properties of the corrosion product film on the surface of the copper-nickel alloy. This results in the copper-nickel alloy of this invention exhibiting excellent corrosion resistance, with its erosion corrosion rate reduced by more than 60% compared to existing copper-nickel alloys.

[0004] The copper-nickel alloys mentioned in the patents, as well as most copper-nickel alloy tubes on the market, mainly rely on the corrosion resistance of the copper-nickel alloy itself for corrosion protection. They can be used normally in some conventional application scenarios, but they are not suitable for use in some scenarios with higher corrosion resistance, and their service life will be greatly reduced. For example, when copper-nickel sleeves are used in marine and ship coolers, the copper-nickel sleeves will be in contact with seawater for a long time, and the corrosion product film on the surface of the copper-nickel sleeves will show corrosion cracking, which will lead to the subsequent aggravation of corrosion of the copper-nickel sleeves. Summary of the Invention

[0005] To overcome the above-mentioned defects of the prior art, embodiments of the present invention provide a corrosion-resistant layer for a copper-nickel bushing and a method for preparing the same.

[0006] A corrosion-resistant layer for a copper-nickel bushing includes a corrosion-resistant outer layer and a corrosion-resistant inner layer, wherein the corrosion-resistant inner layer is disposed between the copper-nickel bushing and the corrosion-resistant outer layer; the base material of the corrosion-resistant outer layer, calculated by weight percentage, is: 56.1-56.9% epoxy resin, 4.2-4.8% nano-zirconia modified material, 7.3-8.3% glass microspheres, 7.3-8.3% glass flakes, 3.6-4.2% xylene, and the remainder is a curing agent.

[0007] Furthermore, the raw materials of the modified nano-zirconia material, calculated by weight percentage, include: 28-32% nano-zirconia, 4.6-5.6% polymeric dispersant, and the remainder is anhydrous ethanol.

[0008] Furthermore, the base material of the treatment liquid for the corrosion-resistant inner layer is calculated by weight percentage as follows: 11.0-11.6% benzotriazole, 0.20-0.30% sodium tungstate, 2.20-2.30% aminotriazole, 0.17-0.23% sodium molybdate, and the remainder is thioacetamide.

[0009] Furthermore, the base material of the corrosion-resistant outer layer, calculated by weight percentage, comprises: 56.5% epoxy resin, 4.5% nano-zirconia modifier, 7.8% glass microspheres, 7.8% glass flakes, 3.9% xylene, and 19.5% curing agent; the raw materials of the nano-zirconia modifier, calculated by weight percentage, include: 30% nano-zirconia, 5.1% polymeric dispersant, and 64.9% anhydrous ethanol; the base material of the treatment liquid of the corrosion-resistant inner layer, calculated by weight percentage, comprises: 11.3% benzotriazole, 0.25% sodium tungstate, 2.25% aminotriazole, 0.20% sodium molybdate, and 86% thioacetamide.

[0010] Furthermore, the curing agent is one of ethylenediamine, hexamethylenediamine, triethylenetetramine, diethylenetriamine, and diethylaminopropylamine; the polymeric dispersant is one of polyurethane or polyester-type polymeric dispersants.

[0011] A method for preparing a corrosion-resistant layer on a copper-nickel bushing, the specific preparation steps of which are as follows:

[0012] Step 1: Weigh the following components from the raw materials: epoxy resin, glass microspheres, glass flakes, xylene, curing agent, nano-zirconia, polymeric dispersant, anhydrous ethanol, and benzotriazole, sodium tungstate, aminotriazole, sodium molybdate, and thioacetamide from the corrosion-resistant outer layer base material.

[0013] Step 2: Add deionized water to the thioacetamide in Step 1 to dissolve and obtain a mixture. Then add benzotriazole, sodium tungstate, aminotriazole and sodium molybdate from Step 1 in sequence and stir evenly to obtain the treatment solution for the corrosion-resistant inner layer.

[0014] Step 3: Immerse the copper-nickel sleeve in anhydrous ethanol for ultrasonic treatment for 10-20 minutes, then clean it with deionized water to obtain the pretreated copper-nickel sleeve.

[0015] Step 4: Immerse the pretreated copper-nickel sleeve from Step 3 into the corrosion-resistant inner layer treatment solution, heat and ultrasonically treat for 2-3 hours, remove and dry to form a corrosion-resistant inner layer on the sleeve wall.

[0016] Step 5: Add the polymeric dispersant from Step 1 to the anhydrous ethanol from Step 1, sonicate for 10-20 minutes, then add the nano-zirconia from Step 1, sonicate for 20-30 minutes to obtain the nano-zirconia modified material.

[0017] Step 6: Add the nano-zirconia modified material from Step 5 to the epoxy resin from Step 1, and sonicate for 10-20 minutes. Then add the glass microspheres, glass flakes and xylene from Step 1 in sequence, and sonicate for 10-20 minutes. Then add the curing agent from Step 1, and sonicate for 5-10 minutes to obtain the base material for the corrosion-resistant outer layer.

[0018] Step 7: The base material of the corrosion-resistant outer layer from Step 6 is evenly coated onto the surface of the corrosion-resistant inner layer and dried to form a corrosion-resistant outer layer on the outside of the corrosion-resistant inner layer of the copper-nickel sleeve, thus obtaining the corrosion-resistant layer of the copper-nickel sleeve.

[0019] Furthermore, in step two, the weight ratio of added deionized water to thioacetamide is (25-30):1; in step three, the ultrasonic frequency is 1.4-1.6MHz and the ultrasonic power is 400-500W.

[0020] Furthermore, in step four, the heating temperature is 55–65°C, the drying time is 12–18 hours, the ultrasonic frequency is 1.4–1.6 MHz, the ultrasonic power is 400–500 W, and the drying process is carried out in an oven at a temperature of 65–75°C; in step five, the ultrasonic frequency is 1.4–1.6 MHz, and the ultrasonic power is 400–500 W.

[0021] Furthermore, in step six, the ultrasonic frequency is 1.4–1.6 MHz and the ultrasonic power is 400–500 W; in step seven, the material is dried in an oven at a temperature of 50–60°C for 7–9 hours.

[0022] Furthermore, in step two, the weight ratio of deionized water to thioacetamide is 27:1; in step three, the ultrasonic frequency is 1.5MHz and the ultrasonic power is 450W; in step four, the heating temperature is 60℃, the drying time is 15 hours, the ultrasonic frequency is 1.5MHz, the ultrasonic power is 450W, and the drying process is carried out in an oven at 70℃; in step five, the ultrasonic frequency is 1.5MHz and the ultrasonic power is 450W; in step six, the ultrasonic frequency is 1.5MHz and the ultrasonic power is 450W; in step seven, the drying process is carried out in an oven at 55℃ for 8 hours.

[0023] The technical effects and advantages of this invention are as follows:

[0024] 1. The corrosion-resistant layer of a copper-nickel bushing prepared using the raw material formula of this invention employs a double-layer corrosion-resistant design with an inner and outer corrosion-resistant layer. This effectively provides dual corrosion resistance to the exterior of the copper-nickel bushing. Even after prolonged use and corrosion damage to the outer corrosion-resistant layer, the inner corrosion-resistant layer can still provide corrosion protection, effectively ensuring the long-term use of the copper-nickel bushing in highly corrosive environments and extending its service life. The combination of thioacetamide and benzotriazole forms a corrosion-resistant inner layer on the surface of the copper-nickel bushing, effectively improving... The hydrophobic properties of the corrosion-resistant inner layer on the surface of the high-copper-nickel bushing reduce the residence time of corrosive liquids on the bushing, thereby effectively improving corrosion resistance. Nano-zirconia modification can, to some extent, hinder the penetration of corrosive media and delay the corrosion reaction. Uniformly dispersed nano-zirconia enhances the physical shielding and corrosion resistance of the corrosion-resistant outer layer, which exhibits excellent salt spray corrosion resistance, high adhesion, and thermal insulation properties. This effectively prevents corrosion cracking of the corrosion-resistant layer on the surface of the copper-nickel bushing, ensuring its corrosion resistance and extending its service life.

[0025] 2. In this invention, deionized water and thioacetamide are dissolved and mixed, then benzotriazole, sodium tungstate, aminotriazole, and sodium molybdate are added and stirred until homogeneous to obtain a corrosion-resistant inner layer treatment solution. This solution facilitates subsequent treatment of copper-nickel bushings. The copper-nickel bushings are then ultrasonically cleaned in anhydrous ethanol, effectively removing oil stains, dirt, etc., from their surface, thus improving the effectiveness of the subsequent corrosion-resistant inner layer treatment solution. The cleaned copper-nickel bushings are then immersed in the corrosion-resistant inner layer treatment solution, and heated with ultrasound to accelerate the copper-nickel... Rapid molding of the corrosion-resistant inner layer on the casing surface; adding a polymeric dispersant to anhydrous ethanol, followed by ultrasonic treatment with nano-zirconia, can effectively improve the contact and encapsulation effect between the polymeric dispersant and nano-zirconia, thereby enhancing the dispersion effect of nano-zirconia; ultrasonically blending the nano-zirconia modified material with other raw materials of the corrosion-resistant outer layer can effectively enhance the blending uniformity and stability of the corrosion-resistant outer layer base material; uniformly coating the base material of the corrosion-resistant outer layer onto the surface of the corrosion-resistant inner layer, followed by drying, forms a corrosion-resistant outer layer on the outside of the corrosion-resistant inner layer of the copper-nickel casing. Detailed Implementation

[0026] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] Example 1:

[0028] This invention provides a corrosion-resistant layer for copper-nickel bushings, comprising a corrosion-resistant outer layer and a corrosion-resistant inner layer, wherein the corrosion-resistant inner layer is disposed between the copper-nickel bushing and the corrosion-resistant outer layer. The base material of the corrosion-resistant outer layer, calculated by weight percentage, comprises: 561g epoxy resin, 42g nano-zirconia modified material, 73g glass microspheres, 73g glass flakes, 36g xylene, and 215g triethylenetetramine. The raw materials of the nano-zirconia modified material, calculated by weight percentage, comprise: 11.76g nano-zirconia, 1.932g polyurethane-type polymeric dispersant, and 28.308g anhydrous ethanol. The base material of the treatment solution for the corrosion-resistant inner layer, calculated by weight percentage, comprises: 11.0g benzotriazole, 0.20g sodium tungstate, 2.20g aminotriazole, 0.17g sodium molybdate, and 86.43g thioacetamide.

[0029] Epoxy resin was purchased from Jinan Yuanxiang Chemical Co., Ltd., item number: 38891-59-7; nano-zirconia was purchased from Shanghai Yingcheng New Materials Co., Ltd., item number: 010; polyurethane polymeric dispersant was purchased from Guangzhou Jingtian Trading Co., Ltd., polyurethane modified dispersant, model: UNIQSPERSE550S, brand: Uniqchem UK; anhydrous ethanol was purchased from Sinopharm Chemical Reagent Co., Ltd., Sinopharm code: 10009218; glass microspheres were purchased from Dongguan Suguang Plastic Raw Materials Co., Ltd., grade: B4300K6; glass flakes were purchased from Dongguan Suguang Plastic Raw Materials Co., Ltd., model: X1. 712, Product No.: 03; Xylene was purchased from Jinan Chuangshi Chemical Co., Ltd., Product No.: HG025; Triethylenetetramine was purchased from Jinan Huifengda Chemical Co., Ltd., Product No.: HFD-049; Benzotriazole was purchased from Shandong Suihua Biotechnology Co., Ltd., Product No.: 2021067752; Sodium tungstate was purchased from Shanghai Yuanye Biotechnology Co., Ltd., Product No.: S61169; Aminotriazole was purchased from Hubei Yunmei Technology Co., Ltd., Product No.: Y0024; Sodium molybdate was purchased from Shanghai Yuanye Biotechnology Co., Ltd., Product No.: S30214; Thioacetamide was purchased from Shanghai Yuanye Biotechnology Co., Ltd., Product No.: V900086.

[0030] This invention also provides a method for preparing a corrosion-resistant layer on a copper-nickel bushing, the specific preparation steps of which are as follows:

[0031] Step 1: Weigh the following components from the raw materials: epoxy resin, glass microspheres, glass flakes, xylene, triethylenetetramine, nano-zirconia, polyurethane-type polymeric dispersant, anhydrous ethanol, and benzotriazole, sodium tungstate, aminotriazole, sodium molybdate, and thioacetamide from the corrosion-resistant outer layer base material.

[0032] Step 2: Add deionized water to the thioacetamide in Step 1 to dissolve and obtain a mixture. Then add benzotriazole, sodium tungstate, aminotriazole and sodium molybdate from Step 1 in sequence and stir evenly to obtain the treatment solution for the corrosion-resistant inner layer.

[0033] Step 3: Immerse the copper-nickel sleeve in anhydrous ethanol for ultrasonic treatment for 15 minutes, and then clean it with deionized water to obtain the pretreated copper-nickel sleeve.

[0034] Step 4: Immerse the pretreated copper-nickel sleeve from Step 3 into the corrosion-resistant inner layer treatment solution, heat and ultrasonically treat for 2.5 hours, remove and dry to form a corrosion-resistant inner layer on the sleeve wall.

[0035] Step 5: Add the polyurethane polymeric dispersant from Step 1 to the anhydrous ethanol from Step 1, sonicate for 15 minutes, then add the nano-zirconia from Step 1, sonicate for 25 minutes to obtain the nano-zirconia modified material.

[0036] Step 6: Add the nano-zirconia modified material from Step 5 to the epoxy resin from Step 1, and sonicate for 15 minutes. Then add the glass microspheres, glass flakes and xylene from Step 1 in sequence, and sonicate for 15 minutes. Then add the triethylenetetramine from Step 1, and sonicate for 8 minutes to obtain the base material for the corrosion-resistant outer layer.

[0037] Step 7: The base material of the corrosion-resistant outer layer in Step 6 is uniformly coated on the surface of the corrosion-resistant inner layer and dried to form a corrosion-resistant outer layer on the outside of the corrosion-resistant inner layer of the copper-nickel sleeve. The thickness of the corrosion-resistant outer layer is 80±10μm, thus obtaining the corrosion-resistant layer of the copper-nickel sleeve.

[0038] In step two, the weight ratio of deionized water to thioacetamide is 27:1; in step three, the ultrasonic frequency is 1.5MHz and the ultrasonic power is 450W; in step four, the heating temperature is 60℃, the drying time is 15 hours, the ultrasonic frequency is 1.5MHz, the ultrasonic power is 450W, and the drying process is carried out in an oven at 70℃; in step five, the ultrasonic frequency is 1.5MHz and the ultrasonic power is 450W; in step six, the ultrasonic frequency is 1.5MHz and the ultrasonic power is 450W; in step seven, the drying process is carried out in an oven at 55℃ for 8 hours.

[0039] Example 2:

[0040] Unlike Example 1, the base material of the corrosion-resistant outer layer, calculated by weight percentage, consists of: 569g of epoxy resin, 48g of nano-zirconia modified material, 83g of glass microspheres, 83g of glass flakes, 42g of xylene, and 175g of triethylenetetramine; the raw materials of the nano-zirconia modified material, calculated by weight percentage, include: 15.36g of nano-zirconia, 2.688g of polyurethane-type polymeric dispersant, and 29.952g of anhydrous ethanol; the base material of the treatment liquid for the corrosion-resistant inner layer, calculated by weight percentage, consists of: 11.6g of benzotriazole, 0.30g of sodium tungstate, 2.30g of aminotriazole, 0.23g of sodium molybdate, and 85.57g of thioacetamide.

[0041] Example 3:

[0042] Unlike Examples 1-2, the base material of the corrosion-resistant outer layer, calculated by weight percentage, consists of: 565g of epoxy resin, 45g of nano-zirconia modified material, 78g of glass microspheres, 78g of glass flakes, 39g of xylene, and 195g of triethylenetetramine; the raw materials of the nano-zirconia modified material, calculated by weight percentage, include: 13.5g of nano-zirconia, 2.295g of polyurethane-type polymeric dispersant, and 29.205g of anhydrous ethanol; the base material of the treatment liquid for the corrosion-resistant inner layer, calculated by weight percentage, consists of: 11.3g of benzotriazole, 0.25g of sodium tungstate, 2.25g of aminotriazole, 0.20g of sodium molybdate, and 86g of thioacetamide.

[0043] Comparative Example 1:

[0044] The difference from Example 3 is that the base material of the corrosion-resistant outer layer, calculated by weight percentage, consists of: 565g of epoxy resin, 78g of glass microspheres, 78g of glass flakes, 39g of xylene, and 240g of triethylenetetramine; the base material of the treatment liquid of the corrosion-resistant inner layer, calculated by weight percentage, consists of: 11.3g of benzotriazole, 0.25g of sodium tungstate, 2.25g of aminotriazole, 0.20g of sodium molybdate, and 86g of thioacetamide.

[0045] Comparative Example 2:

[0046] The difference from Example 3 is that the base material of the corrosion-resistant outer layer, calculated by weight percentage, is: 565g of epoxy resin, 45g of nano-zirconia, 78g of glass microspheres, 78g of glass flakes, 39g of xylene, and 195g of triethylenetetramine; the base material of the treatment liquid of the corrosion-resistant inner layer, calculated by weight percentage, is: 11.3g of benzotriazole, 0.25g of sodium tungstate, 2.25g of aminotriazole, 0.20g of sodium molybdate, and 86g of thioacetamide.

[0047] Comparative Example 3:

[0048] The difference from Example 3 is as follows: the base material of the corrosion-resistant outer layer, calculated by weight percentage, consists of: 565g of epoxy resin, 45g of nano-zirconia modified material, 78g of glass microspheres, 78g of glass flakes, 39g of xylene, and 195g of triethylenetetramine; the raw materials of the nano-zirconia modified material, calculated by weight percentage, include: 13.5g of nano-zirconia, 2.295g of polyurethane-type polymeric dispersant, and 29.205g of anhydrous ethanol; the treatment solution of the corrosion-resistant inner layer, calculated by weight percentage, consists of: 11.3g of benzotriazole, 0.25g of sodium tungstate, 2.25g of aminotriazole, 0.20g of sodium molybdate, and 86g of deionized water.

[0049] Comparative Example 4:

[0050] The difference from Example 3 is that: the base material of the corrosion-resistant outer layer, calculated by weight percentage, consists of: 565g of epoxy resin, 45g of nano-zirconia modified material, 78g of glass microspheres, 78g of glass flakes, 39g of xylene, and 195g of triethylenetetramine; the raw materials of the nano-zirconia modified material, calculated by weight percentage, include: 13.5g of nano-zirconia, 2.295g of polyurethane-type polymeric dispersant, and 29.205g of anhydrous ethanol; the base material of the treatment liquid of the corrosion-resistant inner layer, calculated by weight percentage, consists of: 0.25g of sodium tungstate, 2.25g of aminotriazole, 0.20g of sodium molybdate, and 97.3g of thioacetamide.

[0051] The corrosion-resistant inner and outer layers of the copper-nickel sleeves in the comparative examples and embodiments of this invention were tested. The corrosion-resistant outer layers were tested in Comparative Examples 1, 2, and Examples 1-3. The electrochemical performance of the corrosion-resistant outer layer was evaluated using a three-electrode system with a Reference600+ electrochemical workstation. The copper-nickel sleeve coated with the corrosion-resistant outer layer, a platinum sheet, and a saturated calomel electrode (SCE) were used as the working electrode, auxiliary electrode, and reference electrode, respectively. An acrylic tube was fixed to the surface of the working electrode using screws and bolts, and filled with a 3.5% NaCl solution at 60°C to accelerate the corrosion of the corrosion-resistant outer layer. The effective test area of ​​the working electrode was 12.56 cm². 2 Electrochemical impedance spectroscopy (EIS) was performed in the frequency range of 100 kHz to 10 mHz, with a perturbation voltage of 20 mV. During the impedance test, the copper-nickel sleeve of the corrosion-resistant outer layer was first placed in the electrolyte for 30 minutes to stabilize the open circuit potential. The entire test was conducted in a Faraday electromagnetic shielding box. Comparative Examples 3, 4, and Examples 1-3 tested the corrosion-resistant outer layer and the corrosion-resistant inner layer, using the same operating method as above.

[0052] The test results of the corrosion-resistant outer layer are shown in Table 1:

[0053] Table 1:

[0054]

[0055] The test results of the corrosion-resistant inner layer are shown in Table 2:

[0056] Table 2:

[0057]

[0058] As shown in Tables 1 and 2, the corrosion-resistant layer of the copper-nickel bushing of the present invention adopts a double-layer corrosion-resistant design with a corrosion-resistant inner layer and a corrosion-resistant outer layer. This effectively provides double corrosion resistance to the exterior of the copper-nickel bushing. Even if the corrosion-resistant outer layer is damaged by corrosion after long-term use, the corrosion-resistant inner layer can still provide corrosion protection for the copper-nickel bushing, effectively ensuring the long-term use of the copper-nickel bushing in highly corrosive environments and thus guaranteeing its service life.

[0059] In this invention, in step two, deionized water and thioacetamide are dissolved and mixed, then benzotriazole, sodium tungstate, aminotriazole, and sodium molybdate are added and stirred evenly to obtain a corrosion-resistant inner layer treatment solution, which facilitates subsequent treatment of the copper-nickel bushing with the corrosion-resistant inner layer treatment solution. In step three, the copper-nickel bushing is ultrasonically cleaned in anhydrous ethanol, which effectively removes oil stains, dirt, etc. from the surface of the copper-nickel bushing, facilitating the subsequent treatment of the copper-nickel bushing surface with the corrosion-resistant inner layer treatment solution. Benzotriazole in the base material of the corrosion-resistant inner layer treatment solution acts as a special corrosion inhibitor for copper alloys. Benzotriazole has a synergistic effect with sodium tungstate, aminotriazole, and sodium molybdate. The film surface mainly consists of copper and nickel oxides and copper-nickel-benzotriazole complexes. The composition shows a higher proportion of oxides in the high-temperature film-forming components and a higher proportion of hydroxides in the room-temperature film-forming components. Sodium tungstate, aminotriazole, and sodium molybdate all participate in film formation. Under heating conditions, the reaction can effectively shorten the passivation time and improve corrosion resistance. After adding thioacetamide, the copper-nickel sleeve is placed in the treatment solution. The copper in the copper-nickel sleeve reacts with thioacetamide to form cuprous sulfide and a small amount of cuprous oxide on the surface of the copper-nickel sleeve. The cuprous oxide continues to react with thioacetamide to transform into the more insoluble cuprous sulfide, depositing a dense particulate film composed of small nanoparticles on the surface of the copper-nickel sleeve. The cuprous sulfide has a submicron and nanoscale particle structure, and these particle structures stack up to form a micron-scale cluster structure, thus exhibiting dual-scale or multi-scale properties. The hierarchical structure—similar to a lotus leaf—gives the corrosion-resistant inner layer on the surface of the copper-nickel bushing a high contact angle and a small roll-off angle. The combination of thioacetamide and benzotriazole forms a corrosion-resistant inner layer on the copper-nickel bushing surface, effectively improving its hydrophobic properties and reducing the residence time of corrosive liquids, thus enhancing corrosion resistance. In step four, the cleaned copper-nickel bushing is immersed in the treatment solution for the corrosion-resistant inner layer, and heating and ultrasonic treatment accelerate the rapid formation of the corrosion-resistant inner layer. In the base material of the corrosion-resistant outer layer, a polymeric dispersant coats the nano-zirconia, modifying it and effectively reducing agglomeration. Improving the long-term dispersion stability of nano-zirconia makes the distribution of nano-zirconia in the corrosion-resistant outer layer more uniform, thereby effectively ensuring the corrosion resistance of the outer layer. In step five, the polymeric dispersant is added to anhydrous ethanol, and then nano-zirconia is added and ultrasonically treated, which can effectively improve the contact and encapsulation effect between the polymeric dispersant and nano-zirconia, thereby enhancing the dispersion effect of nano-zirconia. In step six, the modified nano-zirconia material and other raw materials of the corrosion-resistant outer layer are ultrasonically blended, which can effectively enhance the blending uniformity and stability of the corrosion-resistant outer layer base material. In step seven, the base material of the corrosion-resistant outer layer is uniformly coated on the surface of the corrosion-resistant inner layer and dried to form a corrosion-resistant outer layer on the outside of the corrosion-resistant inner layer of the copper-nickel sleeve.Nano-zirconia modification can, to a certain extent, hinder the penetration of corrosive media and delay the corrosion reaction. The unmodified corrosion-resistant outer layer has the worst resistance to corrosion media penetration, while the shielding effect of the nano-zirconia-modified corrosion-resistant outer layer does not continuously increase with increasing nano-zirconia content, but rather shows a pattern of initial enhancement followed by weakening. When nano-zirconia is uniformly dispersed in the coating, its pore-sealing effect is more dominant than its agglomeration effect, resulting in significant corrosion inhibition, fewer pores in the coating, and high double-layer transfer resistance. Modifying the corrosion-resistant outer layer with nano-zirconia significantly improves its electrochemical impedance in a 3.5% NaCl solution at 60℃. After 1440 hours of corrosion, the nano-zirconia-modified epoxy coating showed no significant rust. And cracks; after immersion in 3.5% NaCl solution at 60℃ for 500 hours, the bonding strength of the corrosion-resistant outer layer is always greater than 6MPa; the uniformly dispersed nano-zirconia enhances the physical shielding and corrosion resistance of the corrosion-resistant outer layer, which has excellent salt spray corrosion resistance, high adhesion and heat insulation performance; the corrosion-resistant outer layer provides corrosion protection for the copper-nickel sleeve on the outside of the corrosion-resistant inner layer, which can effectively strengthen the double corrosion protection treatment of the copper-nickel sleeve, thereby enhancing the corrosion resistance of the copper-nickel sleeve, thus ensuring the use of the copper-nickel sleeve in high corrosion resistance scenarios, effectively preventing corrosion cracking of the corrosion-resistant layer on the surface of the copper-nickel sleeve, ensuring the corrosion resistance of the copper-nickel sleeve, and extending the service life of the copper-nickel sleeve.

[0060] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A corrosion-resistant layer for a copper-nickel bushing, characterized in that: The system comprises a corrosion-resistant outer layer and a corrosion-resistant inner layer, wherein the corrosion-resistant inner layer is disposed between the copper-nickel sleeve and the corrosion-resistant outer layer; the base material of the corrosion-resistant outer layer, calculated by weight percentage, is: 56.1-56.9% epoxy resin, 4.2-4.8% nano-zirconia modified material, 7.3-8.3% glass microspheres, 7.3-8.3% glass flakes, 3.6-4.2% xylene, with the remainder being a curing agent; the nano-zirconia modified material... The raw materials, calculated by weight percentage, include: 28-32% nano-zirconia, 4.6-5.6% polymeric dispersant, and the remainder being anhydrous ethanol; the base material of the corrosion-resistant inner layer treatment liquid, calculated by weight percentage, includes: 11.0-11.6% benzotriazole, 0.20-0.30% sodium tungstate, 2.20-2.30% aminotriazole, 0.17-0.23% sodium molybdate, and the remainder being thioacetamide; The specific preparation steps of the corrosion-resistant inner layer are as follows: S1: Add deionized water to thioacetamide, dissolve to obtain a mixture, and then add benzotriazole, sodium tungstate, aminotriazole and sodium molybdate in sequence, stir evenly to obtain the treatment solution for the corrosion-resistant inner layer; the weight ratio of added deionized water to thioacetamide is (25~30):

1. S2: Immerse the copper-nickel sleeve in anhydrous ethanol for ultrasonic treatment for 10-20 minutes, then clean it with deionized water to obtain the pretreated copper-nickel sleeve. S3: Place the pretreated copper-nickel sleeve from step S2 into the treatment solution for the corrosion-resistant inner layer, heat and ultrasonically treat for 2-3 hours, remove and dry to form a corrosion-resistant inner layer on the sleeve wall; the heating temperature is 55-65℃, the drying time is 12-18 hours, the ultrasonic frequency is 1.4-1.6MHz, the ultrasonic power is 400-500W, and the drying is carried out in an oven at a temperature of 65-75℃.

2. The corrosion-resistant layer of a copper-nickel bushing according to claim 1, characterized in that: The base material of the corrosion-resistant outer layer, calculated by weight percentage, consists of: 56.5% epoxy resin, 4.5% nano-zirconia modifier, 7.8% glass microspheres, 7.8% glass flakes, 3.9% xylene, and 19.5% curing agent; the raw materials of the nano-zirconia modifier, calculated by weight percentage, include: 30% nano-zirconia, 5.1% polymeric dispersant, and 64.9% anhydrous ethanol; the base material of the treatment liquid for the corrosion-resistant inner layer, calculated by weight percentage, consists of: 11.3% benzotriazole, 0.25% sodium tungstate, 2.25% aminotriazole, 0.20% sodium molybdate, and 86% thioacetamide.

3. The corrosion-resistant layer of a copper-nickel bushing according to claim 1, characterized in that: The curing agent is one of ethylenediamine, hexamethylenediamine, triethylenetetramine, diethylenetriamine, and diethylaminopropylamine; the polymeric dispersant is one of polyurethane or polyester-type polymeric dispersants.

4. A method for preparing a corrosion-resistant layer for a copper-nickel bushing according to any one of claims 1-3, characterized in that: The specific preparation steps are as follows: Step 1: Weigh the following components from the raw materials: epoxy resin, glass microspheres, glass flakes, xylene, curing agent, nano-zirconia, polymeric dispersant, anhydrous ethanol, and benzotriazole, sodium tungstate, aminotriazole, sodium molybdate, and thioacetamide from the corrosion-resistant outer layer base material. Step 2: Add deionized water to the thioacetamide in Step 1 to dissolve and obtain a mixture. Then add benzotriazole, sodium tungstate, aminotriazole and sodium molybdate from Step 1 in sequence and stir evenly to obtain the treatment solution for the corrosion-resistant inner layer. Step 3: Immerse the copper-nickel sleeve in anhydrous ethanol for ultrasonic treatment for 10-20 minutes, then clean it with deionized water to obtain the pretreated copper-nickel sleeve. Step 4: Immerse the pretreated copper-nickel sleeve from Step 3 into the corrosion-resistant inner layer treatment solution, heat and ultrasonically treat for 2-3 hours, remove and dry to form a corrosion-resistant inner layer on the sleeve wall. Step 5: Add the polymeric dispersant from Step 1 to the anhydrous ethanol from Step 1, sonicate for 10-20 minutes, then add the nano-zirconia from Step 1, sonicate for 20-30 minutes to obtain the nano-zirconia modified material. Step 6: Add the nano-zirconia modified material from Step 5 to the epoxy resin from Step 1, and sonicate for 10-20 minutes. Then add the glass microspheres, glass flakes and xylene from Step 1 in sequence, and sonicate for 10-20 minutes. Then add the curing agent from Step 1, and sonicate for 5-10 minutes to obtain the base material for the corrosion-resistant outer layer. Step 7: The base material of the corrosion-resistant outer layer from Step 6 is evenly coated onto the surface of the corrosion-resistant inner layer and dried to form a corrosion-resistant outer layer on the outside of the corrosion-resistant inner layer of the copper-nickel sleeve, thus obtaining the corrosion-resistant layer of the copper-nickel sleeve.

5. The method for preparing a corrosion-resistant layer for a copper-nickel bushing according to claim 4, characterized in that: In step three, the ultrasonic frequency is 1.4 to 1.6 MHz and the ultrasonic power is 400 to 500 W.

6. The method for preparing a corrosion-resistant layer for a copper-nickel bushing according to claim 5, characterized in that: In step five, the ultrasonic frequency is 1.4 to 1.6 MHz and the ultrasonic power is 400 to 500 W.

7. The method for preparing a corrosion-resistant layer for a copper-nickel bushing according to claim 6, characterized in that: In step six, the ultrasonic frequency is 1.4–1.6 MHz and the ultrasonic power is 400–500 W; in step seven, the material is dried in an oven at a temperature of 50–60 °C for 7–9 hours.

8. The method for preparing a corrosion-resistant layer for a copper-nickel bushing according to claim 7, characterized in that: In step two, the weight ratio of deionized water to thioacetamide is 27:1; in step three, the ultrasonic frequency is 1.5MHz and the ultrasonic power is 450W; in step four, the heating temperature is 60℃, the drying time is 15 hours, the ultrasonic frequency is 1.5MHz, the ultrasonic power is 450W, and the drying process is carried out in an oven at 70℃; in step five, the ultrasonic frequency is 1.5MHz and the ultrasonic power is 450W; in step six, the ultrasonic frequency is 1.5MHz and the ultrasonic power is 450W; in step seven, the drying process is carried out in an oven at 55℃ for 8 hours.

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