Anticorrosive coating of b30 copper-nickel alloy pipe and pipe plating process thereof
Patent Information
- Application Number
- CN202511327216.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-17
- Publication Date
- 2026-09-29
AI Technical Summary
[0004]目前，铜镍合金管内腐蚀防护面临诸多技术挑战：首先，传统牺牲阳极镀层(如镀锌、镀镍等)在实际应用中存在防护寿命短、环境适应性差、耐磨性能不足等问题；其次，针对铜镍合金这类特殊基材，其表面钝化膜(Cu2O/NiO等)严重影响镀层结合力，而常规酸活化处理又容易造成基体过腐蚀，机械打磨对铜镍合金管道会造成较大损伤，目前没有针对铜镍合金管道内壁的前处理工艺；再者，现有化学镀工艺研究主要针对平板试样设计，难以满足管状构件内壁的特殊处理需求-由于管材内腔结构的限制，镀液流动过程中易形成滞留区和涡流，严重影响镀层均匀性
[0025](1)本发明提出了一种针对铜镍合金管材内部独特的前处理工艺，充分解决了针对铜镍合金这类特殊基材常规酸洗活化无法有效去除表面钝化膜，而机械打磨对铜镍合金管材会造成较大损伤的问题，其中高浓度碱和高频超声清洗实现了更好剥落管材内壁的脏污，低速循环和长时室温下的氧化处理形成了便于去除的疏松氧化产物，结合后续高速短时冲刷和高频超声酸洗处理，实现了彻底去除的疏松氧化产物的同时减少酸蚀对基底的损伤，最后的活化则实现了催化活性位点在B30铜镍合金管材内壁的形成，助于镀层结合紧密。
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Abstract
Description
Technical Field
[0001] This invention relates to the field of material surface protection technology, specifically to an anti-corrosion coating for B30 copper-nickel alloy pipes and its plating process. Background Technology
[0002] B30 copper-nickel alloy pipes possess advantages such as excellent resistance to seawater erosion corrosion, high heat transfer coefficient, and superior antifouling performance. Currently, with the continuous development of marine engineering, B30 alloy is widely used. However, with the successive reports of early failure accidents involving B30 alloy pipes, many studies have conducted in-depth research on the original surface film defects and microstructural defects of the alloy. Numerous studies have found that while the self-passivation performance of B30 copper-nickel alloy pipes during use creates excellent corrosion resistance, severe pitting and crevice corrosion occur during the "infancy" of passivation film formation under static water immersion conditions. This is especially true in the inner wall area, where traditional protection methods (such as cathodic protection) are difficult to achieve comprehensive and effective coverage, seriously affecting its service life and the operational safety of the power system.
[0003] Metal surface protection technology is one of the most economical and effective methods to solve alloy corrosion problems. It can significantly improve the surface properties of materials and extend their service life without substantially increasing manufacturing costs. Currently, numerous metal surface protection technologies have been developed, including anodizing, micro-arc oxidation, electroplating, and electroless plating. Among these, electroless plating, due to its simple process and ability to form a uniform and strongly bonded coating on complex irregular structures, has become a research hotspot in the field of corrosion protection for irregularly shaped metals. Historically, electroless plating technology has evolved from early nickel-phosphorus electroless plating processes to more advanced processes such as diversified nickel electroless plating, composite coatings, and multi-layer electroless plating.
[0004] Currently, corrosion protection of copper-nickel alloy pipes faces numerous technical challenges: First, traditional sacrificial anode plating (such as zinc plating and nickel plating) suffers from short protective life, poor environmental adaptability, and insufficient wear resistance in practical applications; second, for special substrates like copper-nickel alloys, the surface passivation film (Cu2O / NiO, etc.) severely affects the coating adhesion, while conventional acid activation treatment easily causes over-corrosion of the substrate, and mechanical grinding can cause significant damage to copper-nickel alloy pipes. Currently, there is no pretreatment process specifically for the inner wall of copper-nickel alloy pipes; third, existing chemical plating process research mainly focuses on flat sample design, which is difficult to meet the special treatment requirements of the inner wall of tubular components—due to the limitations of the pipe's internal cavity structure, stagnant zones and eddies are easily formed during the flow of the plating solution, seriously affecting the uniformity of the coating. Summary of the Invention
[0005] To address the shortcomings of existing technologies, this invention provides a corrosion-resistant coating for B30 copper-nickel alloy pipes and its plating process. It employs a pretreatment process and a rare-earth nano-oxide-reinforced composite nickel plating solution, and designs a plating method suitable for the special structure of the inner wall of the pipe, effectively achieving a uniform and dense chemical coating with strong corrosion resistance and high wear resistance inside the copper-nickel alloy pipe wall.
[0006] To achieve the above objectives, the present invention provides the following technical solution:
[0007] This invention discloses a composite nickel plating solution, which contains metal salts, reducing agents, complexing agents, nanoparticles, and stabilizers.
[0008] Preferably, the composite nickel plating solution contains a metal salt at a concentration of 25-30 g / L, a reducing agent at a concentration of 2-5 g / L, a complexing agent at a concentration of 5-10 g / L, nanoparticles at a concentration of 6-8 g / L, and a stabilizer at a concentration of 1-3 g / L.
[0009] Preferably, the metal salt is one or more of nickel sulfate, copper sulfate, and zinc sulfate; the reducing agent is a mixture of dimethylaminoborane and sodium borohydride; the complexing agent is a mixture of sodium citrate and sodium acetate; the stabilizer is thiourea; and the nanoparticles are nano-rare earth oxides, wherein the nano-rare earth oxides are a mixture of two or more of nano-yttrium oxide, nano-lanthanum oxide, nano-samarium oxide, and nano-cerium oxide.
[0010] Accordingly, the preparation method of the composite nickel plating solution includes the following steps:
[0011] (1) Dissolve the complexing agent and stabilizer in water and mix them evenly to obtain a mixture. Dissolve the metal salt in water and then slowly pour it into the mixture while stirring to obtain a mixed solution (a).
[0012] (2) Stir the mixed solution (a) until homogeneous and heat it to 50-60°C. Dissolve the reducing agent in water and slowly pour it into the mixed solution (a) while stirring to obtain the mixed solution (b).
[0013] (3) Add the nanoparticles to the mixed solution (b) to obtain the mixed solution (c). Finally, dissolve 0.1 g / L SDS and 0.1 g / L SDBS in water and add them to the mixed solution (c) to obtain the mixed solution (d). Place the mixed solution (d) in an ultrasonic water bath at an ultrasonic frequency of 25-40 kHz to obtain a uniformly dispersed nanocomposite nickel plating solution. Adjust the pH value of the solution to 5-7 to obtain the composite nickel plating solution, and keep the temperature of the composite nickel plating solution at 50-60℃.
[0014] Correspondingly, a corrosion-resistant coating for B30 copper-nickel alloy pipes is formed by using the composite nickel plating solution to create a nanoparticle-reinforced composite coating on the inner wall of the B30 copper-nickel alloy pipe as a corrosion-resistant coating through a pipe plating process.
[0015] Correspondingly, a pipe plating process based on the anti-corrosion coating of B30 copper-nickel alloy pipes involves removing surface oxides from the B30 copper-nickel alloy pipes through a pretreatment process, and then using a pipe plating device with ultrasonic treatment to uniformly plate a layer of nanoparticle-reinforced composite coating onto the inner wall of the B30 copper-nickel alloy pipes with a composite nickel plating solution.
[0016] Preferably, the pretreatment process is alkaline washing, oxidation, acid washing, and reduction activation;
[0017] The alkaline solution used for the alkaline washing contains 10%–15% NaOH and a surfactant. The surfactant is a mixture of two or more of the following: 0.1% SDS, 0.1% SDBS, 1 g / L C14-16 olefin sulfonate sodium, or 10 ml / LOP emulsifier. The treatment temperature is 50–60°C, and the solution is circulated and rinsed in a B30 copper-nickel alloy tube for 5 minutes.
[0018] The oxidation solution used in the oxidation process contains 5% H2O2 and 3% citric acid solution, and is circulated and rinsed in a B30 copper-nickel alloy tube at room temperature for 15 minutes.
[0019] The acidic solution used for pickling contains 15%–25% acetic acid and 20%–40% phosphoric acid. The treatment temperature is 50–60°C, and the solution is circulated and rinsed in a B30 copper-nickel alloy tube for 1–2 minutes.
[0020] The activation solution used for reduction and activation contains 10% NaH2PO2 and 0.1 g / L PdCl2 solution. The solution has a pH of 8 and is treated at a temperature of 50-60°C. The solution is then left to stand in a B30 copper-nickel alloy tube for 1-2 minutes.
[0021] Preferably, during the alkaline washing, oxidation, and acid washing processes, the flow rate of the solution used is 0.1–5 m / s; and during the alkaline washing and acid washing processes, the ultrasonic frequency is 25–40 kHz.
[0022] Preferably, the composite nickel plating solution is adjusted to a pH of 5-7 with acetic acid, the flow rate of the composite nickel plating solution is 0.1-1.5 m / s, the ultrasonic frequency is 15-40 kHz, the power is 150-180 W, and the plating time is 60-90 min at a temperature of 50-60℃.
[0023] Preferably, the tube plating device consists of hoses connected to both ends of a B30 copper-nickel alloy tube, with a multi-hole distributor connected to the bottom inlet hose and placed in an ultrasonic water bath filled with composite nickel plating solution; the top hose is connected to an ion pump to backflow the composite nickel plating solution through the B30 copper-nickel alloy tube, the composite nickel plating solution is pumped in from the bottom of the B30 copper-nickel alloy tube, overflows from the top and flows back through the top hose, forming a stable laminar flow.
[0024] The present invention has the following beneficial effects:
[0025] (1) This invention proposes a unique pretreatment process for the interior of copper-nickel alloy pipes, which fully solves the problem that conventional acid pickling and activation cannot effectively remove the surface passivation film for special substrates such as copper-nickel alloys, while mechanical grinding will cause great damage to copper-nickel alloy pipes. Among them, high-concentration alkali and high-frequency ultrasonic cleaning achieve better removal of dirt from the inner wall of the pipe. Low-speed circulation and long-term room temperature oxidation treatment form loose oxidation products that are easy to remove. Combined with subsequent high-speed short-time rinsing and high-frequency ultrasonic acid pickling treatment, the loose oxidation products are thoroughly removed while reducing the damage of acid etching to the substrate. Finally, the activation realizes the formation of catalytic active sites on the inner wall of B30 copper-nickel alloy pipes, which helps the coating to bond tightly.
[0026] (2) This invention uses an acidic electroless nickel plating solution to obtain an electroless plating layer with good wear resistance. The addition of nanoparticles and the use of ultrasonic technology improve the density and wear resistance of the plating layer, making it suitable for the complex seawater scouring environment inside the pipe. At the same time, the corrosion current is reduced by orders of magnitude, effectively extending the protection time of the plating layer and improving the anti-corrosion performance of the plating layer. The nanoparticle-enhanced chemical deposition process provided by this invention significantly reduces the plating layer consumption rate and greatly improves the wear resistance, which is of great significance for inhibiting pitting corrosion of B30 copper-nickel alloy pipes.
[0027] (3) The unique tube plating device design provided by this invention, combined with ultrasonic-assisted technology, ensures the uniformity and density of the coating on the inner wall of the tube. The addition of ultrasonic process in ultrasonic-assisted electroless nickel plating makes the plating solution dispersed evenly. The vertical countercurrent flushing process of the device makes a stable laminar flow inside the tube. The design of the liquid inlet and outlet effectively avoids the generation of pores that may be caused by backflow disturbance. The coating of heat insulation material ensures that the temperature of the plating solution inside the tube is constant, and a more dense and uniform composite coating is achieved on the inner wall of the tube. The overall process is simple to operate and suitable for industrial production. It can significantly improve the service life of B30 copper-nickel alloy tubes in harsh environments. Through this technology, not only is the anti-corrosion performance of the tube optimized, but its long-term reliability and economy are also improved. Attached Figure Description
[0028] Figure 1The images shown are optical micrographs and SEM images of the Ni-B coating reinforced with nano-rare earth oxide particles on the inner wall of the pipe prepared in Example 1; (a) physical image; (b) optical micrograph; (c) electron micrograph;
[0029] Figure 2 Light microscopy (LED) and electron microscopy (SEM) images of conventional Ni-B coatings on the inner walls of pipes prepared for Comparative Examples 2, 3, and 4, and of Ni-B coatings reinforced with nano-rare earth oxide particles after changing the parameters of the pipe plating apparatus; (a) Light microscopy image of Comparative Example 2; (b) Electron microscopy image of Comparative Example 2; (c) Light microscopy image of Comparative Example 3; (d) Electron microscopy image of Comparative Example 3; (e) Light microscopy image of Comparative Example 4; (f) Electron microscopy image of Comparative Example 4;
[0030] Figure 3 SEM images of the self-sacrificing nickel-phosphorus-zinc layer and the multi-element nickel-copper-zinc layer in the B30 copper-nickel alloy tubing prepared for Comparative Examples 13 and 14; (a) SEM image of Comparative Example 13; (b) SEM image of Comparative Example 14;
[0031] Figure 4 The scratch curves are shown in the comparison diagrams of the pretreatment process (Example 1) and the process using only alkaline washing-acid washing (Comparative Example 1); (a) Scratch curve of Example 1; (b) Scratch curve of Comparative Example 1;
[0032] Figure 5 This is a photograph of the tube plating apparatus.
[0033] Figure 6 for Figure 5 Enlarged view of the top of the tube plating apparatus;
[0034] Figure 7 A photograph showing the installation of a tube plating device on multiple B30 copper-nickel alloy tubes for simultaneous nickel plating.
[0035] Figure 8 A photo of the B30 copper-nickel alloy tubing after flexible hoses have been installed at both ends.
[0036] Figure 9 This is a photograph of a B30 copper-nickel alloy pipe wrapped with a thermostatic insulation material. Detailed Implementation
[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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.
[0038] Unless otherwise specified, the technical means used in the implementation examples are conventional means well known to those skilled in the art.
[0039] 1. This invention provides a composite nickel plating solution, wherein the composite nickel plating solution contains a metal salt, a reducing agent, a complexing agent, nanoparticles, and a stabilizer. Specifically: the composite nickel plating solution contains a metal salt at a concentration of 25–30 g / L, a reducing agent at a concentration of 2–5 g / L, a complexing agent at a concentration of 5–10 g / L, nanoparticles at a concentration of 6–8 g / L, and a stabilizer at a concentration of 1–3 g / L.
[0040] Furthermore, the metal salt is one or more of nickel sulfate, copper sulfate, and zinc sulfate, ensuring that the concentration of the metal salt in the composite nickel plating solution is 25-30 g / L. For example, when the metal salt is nickel sulfate and zinc sulfate, their molar ratio can be 2-5:1. The reducing agent is a mixture of dimethylaminoborane and sodium borohydride (the molar ratio of dimethylaminoborane and sodium borohydride is 2-3:1-2), the complexing agent is a mixture of sodium citrate and sodium acetate (the concentration of the two can be 1:1), the stabilizer is thiourea, and the nanoparticles are nano-rare earth oxides, which are mixtures of two or more of nano-yttrium oxide, nano-lanthanum oxide, nano-samarium oxide, and nano-cerium oxide. When multiple nanoparticles are selected, the mass of each nano-rare earth oxide is the same.
[0041] This invention provides a method for preparing a composite nickel plating solution, comprising the following steps:
[0042] (1) Dissolve the complexing agent and stabilizer in water and mix them evenly to obtain a mixed solution. Weigh and mix the metal salts (when there are multiple metal salts), dissolve them in water, and then slowly pour them into the mixed solution while stirring to obtain a mixed solution (a).
[0043] (2) Stir the mixed solution (a) evenly and heat it to 50-60°C. Mix the reducing agent dimethylaminoborane with sodium borohydride at a molar ratio of 2-3:1-2. Dissolve the mixture in water and slowly pour it into the mixed solution (a) while stirring to obtain the mixed solution (b).
[0044] (3) Add the nanoparticles to the mixed solution (b) to obtain the mixed solution (c). Finally, dissolve 0.1 g / L SDS and 0.1 g / L SDBS in water and add them to the mixed solution (c). Add deionized water to 1 L to obtain the mixed solution (d). Place the mixed solution (d) in an ultrasonic water bath and apply ultrasonic treatment at a frequency of 25-40 kHz to obtain a uniformly dispersed nanocomposite nickel plating solution. Adjust the pH of the solution to 5-7 with acetic acid or ammonia to obtain an acidic chemical nickel plating solution, and always keep the plating solution temperature at 50-60℃.
[0045] 2. This invention provides an anti-corrosion coating for B30 copper-nickel alloy pipes. The composite nickel plating solution is used in a pipe plating process to form a nanoparticle-reinforced composite coating on the inner wall of the B30 copper-nickel alloy pipe as an anti-corrosion coating.
[0046] 3. This invention provides a tube plating process for an anti-corrosion coating on B30 copper-nickel alloy pipes, comprising the following steps:
[0047] (1) Remove surface oxides from B30 copper-nickel alloy tubing through a pretreatment process;
[0048] The pretreatment process includes alkaline washing, oxidation, acid washing, and reduction activation, namely, alkaline washing to remove oil stains, oxidation to remove the original passivation film, acid washing to remove loose oxidation products, and reduction activation to generate catalytic sites.
[0049] Specifically, the purpose of the alkaline washing is to remove oil and dirt from the inner surface of the B30 copper-nickel alloy pipe. The alkaline solution used for the washing contains 10%–15% NaOH and a surfactant. The surfactant is a mixture of two or more of the following: 0.1% SDS (sodium dodecyl sulfate), 0.1% SDBS (sodium dodecylbenzene sulfonate), 1 g / L C14-16 olefin sulfonate, and 10 ml / L OP emulsifier. The specific operation is as follows: the B30 copper-nickel alloy pipe is immersed in an alkaline solution at a temperature of 50–60°C and circulated for 5–10 minutes at a flow rate of 2.5–5 m / s, while simultaneously using ultrasound at a frequency of 30–40 kHz for 5–10 minutes. The high concentration of alkali and high-frequency ultrasound are mainly to better remove dirt from the inner wall of the pipe.
[0050] The purpose of the oxidation is to break down the initial passivation film on the surface and generate loose oxidation products. The oxidation solution used in the oxidation contains 5% H2O2 and 3% citric acid solution. The specific operation is as follows: after filling the inside of the pipe with the oxidation solution, it is circulated and flushed at low speed for 15 minutes at room temperature, with a flow rate of 0.1 to 1 m / s. The low-speed circulation and long room temperature reaction are mainly to thoroughly break down the passivation film and form loose oxidation products that are easy to remove, while also protecting the substrate from oxidation.
[0051] The purpose of pickling is to thoroughly remove the loose oxide products generated during oxidation, exposing a smooth substrate. The acidic solution used for pickling contains 15%–25% acetic acid and 20%–40% phosphoric acid. The specific procedure is as follows: after filling the inside of the pipe with the pickling solution, it is subjected to high-speed rinsing for 1–2 minutes at a temperature of 50–60°C and an ultrasonic frequency of 30–40 kHz, with a flow rate of 2.5–5 m / s. The high-speed, short-time rinsing and high-frequency ultrasound are primarily to thoroughly remove the loose oxide products while minimizing acid corrosion damage to the substrate.
[0052] The purpose of the activation is to generate catalytically active sites. The activation solution used for reduction activation contains 10% NaH2PO2 and 0.1 g / L PdCl2 solution, and the solution pH = 8. The specific operation is as follows: after filling the inside of the tube with the activation solution, the tube is left to stand for 1 to 2 minutes at a treatment temperature of 50-60℃ inside a B30 copper-nickel alloy tube.
[0053] (2) Then, a tube plating device is used with ultrasonic treatment; that is, in order to ensure the dispersion of the composite nickel plating solution without affecting the deposition of metal ions, ultrasonic treatment is performed at the same time as plating. The ultrasonic frequency is 15-40kHz and the power is 150-180W. The pH value of the composite nickel plating solution is adjusted to 5-7 with acetic acid or ammonia. In order to ensure that the coating is uniform and dense, the flow rate of the composite nickel plating solution is 0.1-1.5m / s. The plating is carried out for 60-90 minutes at a temperature of 50-60℃, so that the composite nickel plating solution is uniformly plated with a layer of nanoparticle-reinforced composite coating on the inner wall of the B30 copper-nickel alloy tube, thereby achieving long-term corrosion inhibition of the B30 copper-nickel alloy.
[0054] The composite nickel plating solution used in the ultrasonic-assisted electroless nickel plating (combined with a tube plating device) process is an acidic electroless nickel plating solution. The acidic electroless nickel plating solution contains metal salts, reducing agents, complexing agents, nanoparticles, and stabilizers. Among them, metal salts act as the active force driving the reaction. The reducing agent reduces hydrogen embrittlement by adding element B to the coating. The complexing agent maintains the stability of the pH value and the plating solution by complexing excess reaction products in the solution. The stabilizer avoids stress cracking of the coating caused by excessively fast plating speed by controlling the reaction rate. The addition of nanoparticles is to reduce the overall corrosion current of the film layer and enhance wear resistance.
[0055] Specifically: See reference Figure 5 As shown, the tube plating device consists of: flexible hoses connected to both ends of a B30 copper-nickel alloy tube; a multi-hole distributor connected to the bottom inlet hose to ensure uniform initial flow field; and the tube is placed in an ultrasonic water bath filled with composite nickel plating solution (water bath temperature 50-60℃); a vertical countercurrent rinsing process is adopted, with an ion pump connected to the top hose to push the composite nickel plating solution countercurrently through the B30 copper-nickel alloy tube; the composite nickel plating solution is pumped in from the bottom of the tube (opposite to gravity), overflows from the top, and flows back through the top hose to form a stable laminar flow.
[0056] Furthermore, the porous distributor is one of small-pore distribution, medium-pore distribution, and large-pore distribution.
[0057] Furthermore, to avoid uneven coating caused by backflow disturbance, the top outlet section is equipped with a gradually expanding transition section with an expansion angle of 10–15°. (Reference) Figure 6As described above, a connector is connected to the top of the B30 copper-nickel alloy pipe. The inner diameter of the connector gradually decreases from bottom to top, and the expansion angle is 10 to 15°. The top end of the connector is connected to a flexible hose, and the bottom end is connected to the end of the B30 copper-nickel alloy pipe through the flexible hose.
[0058] Furthermore, such as Figure 5 As shown, to ensure a constant temperature of the plating solution inside the pipe, the entire B30 copper-nickel alloy pipe is wrapped with a constant temperature insulation material to maintain the temperature of the composite nickel plating solution inside the B30 copper-nickel alloy pipe at 50-60°C. The constant temperature insulation material is one of rock wool, glass wool, and aluminum silicate fiber to avoid uneven plating due to temperature drop.
[0059] Based on the installation of the aforementioned tube plating device and B30 copper-nickel alloy tubing, multiple B30 copper-nickel alloy tubings can be installed to simultaneously perform nickel plating operations in the composite nickel plating solution, as detailed below. Figure 7 , 8 As shown, multiple B30 copper-nickel alloy pipes can be nickel plated simultaneously, increasing nickel plating efficiency. Figure 9 A schematic diagram showing a single B30 copper-nickel alloy tube wrapped with thermostatic insulation material.
[0060] The present invention will be further described below with reference to specific embodiments.
[0061] All raw materials used in the following examples were commercially available.
[0062] Example 1
[0063] (1) Pipe pretreatment
[0064] Prepare an alkaline cleaning solution containing 10% sodium hydroxide, 0.1% SDS, and 10 ml / L OP-emulsifier. Immerse the B30 copper-nickel alloy pipe in the alkaline cleaning solution at 50°C and perform high-speed rinsing at 4 m / s, followed by ultrasonic cleaning at 40 kHz for 5 min.
[0065] Prepare an oxidation solution containing 5% H2O2 and 3% citric acid solution; fill the B30 copper-nickel alloy pipe with the oxidation solution and then circulate it at low speed for 15 minutes at room temperature with a flow rate of 0.2 m / s for 15 minutes.
[0066] Prepare a pickling solution containing 25% acetic acid and 20% phosphoric acid. Heat the pickling solution to 60°C, fill the B30 copper-nickel alloy pipe with the pickling solution, and then flush it at high speed with an ultrasonic frequency of 40kHz at a flow rate of 5m / s for 2 minutes.
[0067] Prepare an activation solution containing 10% NaH2PO2 and 0.1 g / L PdCl2 solution with pH = 8. Heat the activation solution to 60°C, fill the B30 copper-nickel alloy pipe with the activation solution, and let it stand for 1 minute inside the B30 copper-nickel alloy pipe.
[0068] In this embodiment, the alkaline washing solution, oxidation solution, acid washing solution, and activation solution are all prepared using deionized water.
[0069] (2) Prepare composite nickel plating solution (i.e., acidic electroless nickel plating solution).
[0070] 2.1 Dissolve 5 g / L sodium citrate, 5 g / L sodium acetate and 2 g / L thiourea in water and mix them evenly to obtain a mixed solution. Weigh nickel sulfate and zinc sulfate separately at a molar ratio of 5:1 and mix them. Dissolve them in water and then slowly pour them into the mixed solution while stirring to obtain a mixed solution (a).
[0071] 2.2 Stir the mixed solution (a) until homogeneous and heat it to 60°C. Mix dimethylaminoborane and sodium borohydride at a molar ratio of 3:1, dissolve them in water, and slowly pour the mixture into the mixed solution (a) while stirring to obtain a mixed solution (b). The mixed solution (b) contains: 25 g / L of metal salts (nickel sulfate, zinc sulfate), 3 g / L of dimethylaminoborane, 1 g / L of sodium borohydride, 5 g / L of sodium acetate, 5 g / L of sodium citrate, and 2 g / L of thiourea.
[0072] 2.3 Take 4g of nano-yttrium oxide and 4g of nano-lanthanum oxide and add them to the mixed solution (b) to obtain mixed solution (c). Finally, dissolve 0.1g / L SDS and 0.1g / L SDBS in water and add them to mixed solution (c). Add deionized water to 1L to obtain mixed solution (d). Place mixed solution (d) in an ultrasonic water bath and apply ultrasonic treatment at a frequency of 25kHz to obtain a uniformly dispersed nano-composite nickel plating solution. Adjust the pH of the solution to 6.5 with acetic acid to obtain an acidic electroless nickel plating solution, and always keep the plating solution temperature at 60℃.
[0073] (3) Constructing a chemical tube plating apparatus
[0074] The pretreated B30 copper-nickel alloy tube is connected to both ends with flexible tubes (such as rubber tubes). The bottom inlet tube is connected to a porous distributor with a 1mm orifice. The tube is placed in an ultrasonic water bath filled with composite nickel plating solution, and the plating solution temperature is maintained at 60℃. The top tube is connected to an ion pump to pump the composite nickel plating solution backflow through the B30 copper-nickel alloy tube. The composite nickel plating solution is pumped in from the bottom of the tube (opposite to gravity), overflows from the top, and flows back through the top tube. The outlet section is equipped with a gradually expanding transition section with an expansion angle of 15° to form a stable laminar flow. The tube is wrapped with lightweight glass wool for heat insulation. The acidic chemical nickel plating solution is slowly flowed into the inner wall of the tube through the flexible tube at a flow rate of 1.5m / s, and ultrasonic plating at a frequency of 25kHz is applied for 1.5h. After plating, the tube is removed, rinsed with deionized water, and dried to obtain a self-sacrificing nanoparticle reinforced B30 copper-nickel alloy tube.
[0075] SEM image of the nanoparticle-reinforced coating in the B30 copper-nickel alloy tube prepared in Example 1 is shown below. Figure 1 .
[0076] Comparative Example 1
[0077] Same as Example 1, except that: the pretreatment of the pipes only involves alkaline washing and acid washing (the specific process is the same as in Example 1); the remaining steps are the same as in Example 1.
[0078] Comparative Example 2
[0079] Same as Example 1, except that the acidic electroless nickel plating solution does not contain nanoparticles and surfactants. The specific preparation method is as follows:
[0080] (1) Sodium citrate, sodium acetate and thiourea are dissolved in water and mixed evenly to obtain a mixed solution. Nickel sulfate and zinc sulfate are weighed and mixed at a molar ratio of 5:1, dissolved in water, and then slowly poured into the above mixed solution while stirring to obtain a mixed solution (a).
[0081] (2) Stir the mixed solution (a) until homogeneous and heat it to 60°C. Mix dimethylaminoborane and sodium borohydride at a molar ratio of 3:1, dissolve them in water, and slowly pour them into the mixed solution (a) while stirring to obtain mixed solution (b). Mixed solution (b) contains: 25 g / L of metal salts (nickel sulfate, zinc sulfate), 3 g / L of dimethylaminoborane, 1 g / L of sodium borohydride, 5 g / L of sodium acetate, 5 g / L of sodium citrate, and 2 g / L of thiourea. Add deionized water to 1 L to obtain mixed solution (c). Place mixed solution (c) in an ultrasonic water bath and apply ultrasonic treatment at a frequency of 25 kHz to obtain a uniformly dispersed nanocomposite electroless nickel plating solution. Adjust the pH of the solution to 6.5 with acetic acid to obtain an acidic electroless nickel plating solution, and always keep the plating solution temperature at 60°C.
[0082] The remaining steps are the same as in Example 1.
[0083] Comparative Example 3
[0084] Same as Example 1, except that the tube plating apparatus has changed, and the specific setup method is as follows:
[0085] The pretreated B30 copper-nickel alloy tube was connected to hoses at both ends. The bottom inlet hose was connected to a porous distributor with a 2mm orifice. The tube was placed in an ultrasonic water bath filled with composite nickel plating solution, and the solution temperature was maintained at 60℃. The top hose was connected to an ion pump to pump the composite nickel plating solution backflow through the B30 copper-nickel alloy tube. The composite nickel plating solution was pumped in from the bottom of the tube (opposite to gravity), overflowed from the top, and flowed back through the top hose. The outlet section was configured with a gradually expanding transition section with an expansion angle of 10° to form a stable laminar flow. The tube was completely wrapped with rock wool for heat insulation. The composite nickel plating solution flowed into the inner wall of the tube through a rubber tube at a flow rate of 1m / s, and ultrasonic plating at a frequency of 25kHz was applied for 1.5h. After plating, the tube was removed, rinsed with deionized water, and dried to obtain a self-sacrificing nanoparticle reinforced B30 copper-nickel alloy tube.
[0086] The remaining steps are the same as in Example 1.
[0087] Comparative Example 4
[0088] Same as Example 1, except that the tube plating apparatus has changed, and the specific setup method is as follows:
[0089] The pretreated B30 copper-nickel alloy tube was connected to hoses at both ends. The bottom inlet hose was connected to a porous distributor with a 3mm orifice. The tube was placed in an ultrasonic water bath filled with composite nickel plating solution, and the temperature of the composite nickel plating solution was maintained at 60℃. The top hose was connected to an ion pump to pump the plating solution backflow through the B30 copper-nickel alloy tube. The composite nickel plating solution was pumped in from the bottom of the tube (opposite to gravity), overflowed from the top, and flowed back through the top hose. The outlet section was configured with a gradually expanding transition section with an expansion angle of 15° to form a stable laminar flow. The entire tube was wrapped with rock wool for heat insulation. The composite nickel plating solution was flowed into the inner wall of the tube through a rubber tube at a flow rate of 0.5m / s, and ultrasonic plating at a frequency of 25kHz was applied for 1.5h. After plating, the tube was removed, rinsed with deionized water, and dried to obtain a self-sacrificing nanoparticle reinforced B30 copper-nickel alloy tube.
[0090] The remaining steps are the same as in Example 1.
[0091] XRD and SEM tests revealed that the average grain size of the nanocomposite coating in Example 1 was 40 nm, which is an order of magnitude finer than that of ordinary coatings. Scratch tests were conducted under conditions of a sliding speed of 10 cm / s, a sliding distance of 200 m, and pressure increasing from 0 to 100 N. The results showed that the failure pressure of the nanocomposite coating in Example 1 was significantly better than that of the nanocomposite coating in Comparative Example 1 without alkaline washing-acid washing pretreatment. This indicates that the alkaline washing-oxidation-acid washing-activation pretreatment process proposed in this invention for B30 copper-nickel alloy pipes effectively improves the adhesion of the coating. In the static water immersion test, Example 1 showed better protective performance than Comparative Example 2 without the addition of nano-rare earth oxide particles. The coating in Example 1 was completely consumed after 6 months, exposing the uncorroded silver-gray substrate, while the coating in Comparative Example 2 showed damage after only 3 months. This demonstrates that the nickel-rare earth oxide composite coating process effectively improves the lifespan of the coating and provides corrosion protection for B30 copper-nickel alloy pipes.
[0092] Comparison images of the inner wall coatings of pipes in Example 1 and Comparative Examples 2, 3, and 4 using optical microscopy and electron microscopy are shown below. Figure 2 ,Depend on Figure 2 It can be seen that the coating of Example 1 has no pores compared to Comparative Example 2, reflecting that the dispersion state of nanoparticles in the composite nickel plating solution has a very good influence on the uniformity of the final coating. The coating of Example 1 has a more uniform cell distribution than Comparative Examples 3 and 4, indicating that increasing the flow rate can reduce the formation of pores to a certain extent compared to the sample with a low flow rate. The coating cells are more tightly bonded, and a chemical coating with full coverage and no obvious defects can be prepared on the inner wall of B30 pipe.
[0093] Example 2
[0094] (1) Pipe pretreatment
[0095] Prepare an alkaline cleaning solution containing 15% sodium hydroxide, 0.1% SDBS, and 1 g / L C14-16 olefin sulfonate. Immerse the B30 copper-nickel alloy pipe in the alkaline cleaning solution at 60°C and perform high-speed rinsing at 5 m / s, followed by ultrasonic cleaning at 40 kHz for 5 min.
[0096] Prepare an oxidation solution containing 5% H2O2 and 3% citric acid solution; fill the B30 copper-nickel alloy pipe with the oxidation solution and then circulate it at low speed for 15 minutes at room temperature with a flow rate of 0.1 m / s for 15 minutes.
[0097] Prepare a pickling solution containing 15% acetic acid and 40% phosphoric acid. Heat the pickling solution to 60°C, fill the B30 copper-nickel alloy pipe with the pickling solution, and then flush it at high speed with an ultrasonic frequency of 40kHz at a flow rate of 5m / s for 1min.
[0098] Prepare an activation solution containing 10% NaH2PO2 and 0.1 g / L PdCl2 solution with pH = 8. Heat the activation solution to 50°C, fill the B30 copper-nickel alloy pipe with the activation solution, and let it stand for 2 minutes.
[0099] (2) Prepare composite nickel plating solution (i.e., acidic electroless nickel plating solution).
[0100] 2.1 Sodium citrate, sodium acetate and thiourea were dissolved in water and mixed evenly to obtain a mixed solution. Nickel sulfate and zinc sulfate were weighed and mixed at a molar ratio of 2:1, dissolved in water, and then slowly poured into the mixed solution while stirring to obtain a mixed solution (a).
[0101] 2.2 Stir the mixed solution (a) until homogeneous and heat it to 50°C. Mix dimethylaminoborane and sodium borohydride at a molar ratio of 2:1, dissolve them in water, and slowly pour the mixture into the mixed solution (a) while stirring to obtain a mixed solution (b). The mixed solution (b) contains: 30 g / L of metal salts (nickel sulfate, zinc sulfate), 3 g / L of dimethylaminoborane, 1.5 g / L of sodium borohydride, 7 g / L of sodium acetate, 3 g / L of sodium citrate, and 3 g / L of thiourea.
[0102] 2.3 Take 4g of nano-cerium oxide and 4g of nano-samarium oxide and add them to the mixed solution (b) to obtain mixed solution (c). Finally, dissolve 0.1g / L SDS and 0.1g / L SDBS in water and add them to mixed solution (c). Add deionized water to 1L to obtain mixed solution (d). Place mixed solution (d) in an ultrasonic water bath and apply ultrasonic treatment at a frequency of 40kHz to obtain a uniformly dispersed nano-composite nickel plating solution. Adjust the pH of the solution to 6 with acetic acid to obtain an acidic chemical nickel plating solution, and always keep the plating solution temperature at 50℃.
[0103] (3) Constructing a chemical tube plating apparatus
[0104] The pretreated B30 copper-nickel alloy tube is connected to both ends with flexible tubes (such as rubber tubes). The bottom inlet tube is connected to a porous distributor with a 1mm orifice. The tube is placed in an ultrasonic water bath filled with composite nickel plating solution, and the temperature of the composite nickel plating solution is maintained at 50℃. The top tube is connected to an ion pump to pump the composite nickel plating solution backflow through the B30 copper-nickel alloy tube. The composite nickel plating solution is pumped in from the bottom of the tube (opposite to gravity), overflows from the top, and flows back through the top tube. The outlet section is equipped with a gradually expanding transition section with an expansion angle of 15° to form a stable laminar flow. The entire tube is wrapped with lightweight glass wool for heat insulation. The composite nickel plating solution is slowly flowed into the inner wall of the tube through the rubber tube at a flow rate of 1.5m / s, and ultrasonic plating at a frequency of 40kHz is applied for 1.5h. After plating, the tube is removed, rinsed with deionized water, and dried to obtain a self-sacrificing nanoparticle reinforced B30 copper-nickel alloy tube.
[0105] Comparative Example 5
[0106] Same as Example 2, except that the pretreatment only involves alkaline washing and acid washing (the specific process is the same as in Example 1), and the remaining steps are the same as in Example 2.
[0107] Comparative Example 6
[0108] Same as Example 2, except that the acidic electroless nickel plating solution does not contain nanoparticles and surfactants. The specific preparation method is as follows:
[0109] (1) Sodium citrate, sodium acetate and thiourea are dissolved in water and mixed evenly to obtain a mixed solution. Nickel sulfate and zinc sulfate are weighed and mixed at a molar ratio of 2:1, dissolved in water, and then slowly poured into the above mixed solution while stirring to obtain a mixed solution (a).
[0110] (2) Stir the mixed solution (a) evenly and heat it to 50°C. Mix dimethylaminoborane and sodium borohydride at a molar ratio of 2:1, dissolve them in water, and slowly pour them into the mixed solution (a) while stirring to obtain mixed solution (b). Mixed solution (b) contains: 30 g / L of metal salts (nickel sulfate, zinc sulfate), 3 g / L of dimethylaminoborane, 1.5 g / L of sodium borohydride, 7 g / L of sodium acetate, 3 g / L of sodium citrate, and 3 g / L of thiourea. Add deionized water to 1 L to obtain mixed solution (c). Place mixed solution (c) in an ultrasonic water bath and apply ultrasonic treatment at a frequency of 40 kHz to obtain a uniformly dispersed nanocomposite electroless nickel plating solution. Adjust the pH of the solution to 6 with acetic acid to obtain an acidic electroless nickel plating solution, and always keep the plating solution temperature at 50°C.
[0111] The remaining steps are the same as in Example 2.
[0112] Comparative Example 7
[0113] Same as Example 1, except that the chemical tube plating apparatus has been changed, and the specific setup method is as follows:
[0114] The pretreated B30 copper-nickel alloy tube is connected to both ends with flexible tubes (such as rubber tubes). The bottom inlet tube is connected to a porous distributor with a 2mm orifice. The tube is placed in an ultrasonic water bath filled with composite nickel plating solution, and the plating solution temperature is maintained at 50℃. The top tube is connected to an ion pump to pump the composite nickel plating solution backflow through the B30 copper-nickel alloy tube. The composite nickel plating solution is pumped in from the bottom of the tube (opposite to gravity), overflows from the top, and flows back through the top tube. The outlet section is configured with a gradually expanding transition section with an expansion angle of 10° to form a stable laminar flow. The tube is completely wrapped with rock wool for heat insulation. The acidic chemical nickel plating solution flows into the inner wall of the tube through the rubber tube at a flow rate of 1m / s, and ultrasonic frequency of 40kHz is applied for plating for 1.5h. After plating, the tube is removed, rinsed with deionized water, and dried to obtain a self-sacrificing nanoparticle reinforced B30 copper-nickel alloy tube.
[0115] The remaining steps are the same as in Example 2.
[0116] Comparative Example 8
[0117] Same as Example 2, except that the chemical tube plating apparatus has been changed, and the specific setup method is as follows:
[0118] The pretreated B30 copper-nickel alloy tube is connected to both ends with flexible tubes (such as rubber tubes). The bottom inlet tube is connected to a porous distributor with a 3mm orifice. The tube is placed in an ultrasonic water bath filled with composite nickel plating solution, and the plating solution temperature is maintained at 50℃. The top tube is connected to an ion pump to pump the composite nickel plating solution backflow through the B30 copper-nickel alloy tube. The composite nickel plating solution is pumped in from the bottom of the tube (opposite to gravity), overflows from the top, and flows back through the top tube. The outlet section is configured with a gradually expanding transition section with an expansion angle of 15° to form a stable laminar flow. The entire tube is wrapped with aluminum silicate fiber for heat insulation. The acidic chemical nickel plating solution flows into the inner wall of the tube through the rubber tube at a flow rate of 0.5m / s, and ultrasonic plating at a frequency of 40kHz is applied for 1.5h. After plating, the tube is removed, rinsed with deionized water, and dried to obtain a self-sacrificing nanoparticle reinforced B30 copper-nickel alloy tube.
[0119] The remaining steps are the same as in Example 2.
[0120] XRD and SEM tests revealed that the average grain size of the nanocomposite coating in Example 2 was 37 nm, which is an order of magnitude finer than that of general coatings. Scratch tests were conducted at a sliding speed of 10 cm / s, a sliding distance of 200 m, and a pressure increasing from 0 to 100 N. The results showed that the failure pressure of the nanocomposite coating in Example 2 was significantly better than that of the nanocomposite coating in Comparative Example 5 without alkaline washing-acid washing pretreatment. This indicates that the alkaline washing-oxidation-acid washing-activation pretreatment process proposed in this invention for B30 copper-nickel alloy pipes effectively improves the adhesion of the coating. The coating in Example 2 showed no pores compared to Comparative Example 6, reflecting the excellent influence of the dispersion state of nanoparticles in the acidic electroless nickel plating solution on the uniformity of the final coating. The coating in Example 2 had a more uniform cell distribution than Comparative Examples 7 and 8, indicating that increasing the flow rate can reduce pore formation to some extent compared to samples with lower flow rates. The coating cells were more tightly bonded, essentially achieving full coverage of the inner wall of B30 pipes with no obvious defects in the electroless coating. In the static water immersion test, Example 2 showed better protective performance than Comparative Example 5, which did not add nano-rare earth oxide particles. The coating in Example 2 was still partially present after 6 months, and no obvious corrosion was observed in the exposed substrate. In contrast, the coating in Comparative Example 5 was damaged after 3 months. This proves that the tube plating nickel-rare earth oxide composite coating process effectively improves the life of the coating and provides corrosion protection for B30 copper-nickel alloy tubes.
[0121] Example 3
[0122] (1) Pipe pretreatment
[0123] Prepare an alkaline cleaning solution containing 15% sodium hydroxide, 10 ml / L of OP-emulsifier, and 1 g / L of C14-16 olefin sulfonate. Immerse the B30 copper-nickel alloy pipe in the alkaline cleaning solution at 50°C and perform high-speed rinsing at 5 m / s, followed by ultrasonic cleaning at 30 kHz for 5 min.
[0124] Prepare an oxidation solution containing 5% H2O2 and 3% citric acid solution; fill the B30 copper-nickel alloy pipe with the oxidation solution and then circulate it at low speed at room temperature for 15 minutes.
[0125] Prepare a pickling solution containing 20% acetic acid and 30% phosphoric acid. Heat the pickling solution to 55°C, fill the B30 copper-nickel alloy pipe with the pickling solution, and then flush it at high speed for 2 minutes under ultrasonic treatment at a frequency of 30kHz and a flow rate of 5m / s.
[0126] Prepare an activation solution containing 10% NaH2PO2 and 0.1 g / L PdCl2 solution with pH = 8. Heat the activation solution to 60°C, fill the B30 copper-nickel alloy pipe with the activation solution, and let it stand for 1 minute inside the B30 copper-nickel alloy pipe.
[0127] (2) Preparation of acidic electroless nickel plating solution
[0128] 2.1 Sodium citrate, sodium acetate and thiourea were dissolved in water and mixed evenly to obtain a mixed solution. Nickel sulfate and zinc sulfate were weighed and mixed at a molar ratio of 3:1, dissolved in water, and then slowly poured into the above mixed solution while stirring to obtain a mixed solution (a).
[0129] 2.2 Stir the mixed solution (a) until homogeneous and heat it to 50°C. Mix dimethylaminoborane and sodium borohydride at a molar ratio of 3:2, dissolve them in water, and slowly pour the mixture into the mixed solution (a) while stirring to obtain a mixed solution (b). The mixed solution (b) contains: 30 g / L of metal salts (nickel sulfate, zinc sulfate), 3 g / L of dimethylaminoborane, 2 g / L of sodium borohydride, 3 g / L of sodium acetate, 7 g / L of sodium citrate, and 3 g / L of thiourea.
[0130] 2.3 Take 2g of nano-yttrium oxide, 2g of nano-samarium oxide and 2g of nano-lanthanum oxide and add them to the mixed solution (b) to obtain mixed solution (c). Finally, dissolve 0.1g / L SDS and 0.1g / L SDBS in water and add them to mixed solution (c). Add deionized water to 1L to obtain mixed solution (d). Place mixed solution (d) in an ultrasonic water bath and apply ultrasonic treatment at a frequency of 40kHz to obtain a uniformly dispersed nanocomposite electroless nickel plating solution. Adjust the pH of the solution to 6 with acetic acid to obtain an acidic electroless nickel plating solution, and always keep the plating solution temperature at 50℃.
[0131] (3) Constructing a chemical tube plating apparatus
[0132] The pretreated B30 copper-nickel alloy tube is connected to both ends with flexible tubes (such as rubber tubes). The bottom inlet tube is connected to a porous distributor with a 1mm orifice. The tube is placed in an ultrasonic water bath filled with an acidic electroless nickel plating solution, and the temperature of the solution is maintained at 55℃. The top tube is connected to an ion pump to pump the acidic electroless nickel plating solution backflow through the B30 copper-nickel alloy tube. The solution is pumped in from the bottom of the tube (opposite to gravity), overflows from the top, and flows back through the top tube. The outlet section has a gradually expanding transition section with an expansion angle of 10° to form a stable laminar flow. The tube is then completely wrapped with lightweight glass wool for heat insulation. The acidic electroless nickel plating solution is slowly injected into the inner wall of the tube through the rubber tube at a flow rate of 0.5m / s, and ultrasonic plating at a frequency of 30kHz is applied for 1.5 hours. After plating, the tube is removed, rinsed with deionized water, and dried to obtain a self-sacrificing nanoparticle-reinforced B30 copper-nickel alloy tube.
[0133] Comparative Example 9
[0134] Same as Example 3, except that: the pretreatment only involves alkaline washing and acid washing (the process is the same as in Example 3), and the other steps are the same as in Example 3.
[0135] Comparative Example 10
[0136] Same as Example 3, except that the acidic electroless nickel plating solution does not contain nanoparticles and surfactants. The specific preparation method is as follows:
[0137] (1) Sodium citrate, sodium acetate and thiourea are dissolved in water and mixed evenly to obtain a mixed solution. Nickel sulfate and zinc sulfate are weighed and mixed at a molar ratio of 3:1, dissolved in water, and then slowly poured into the above mixed solution while stirring to obtain a mixed solution (a).
[0138] (2) Stir the mixed solution (a) evenly and heat it to 50°C. Mix dimethylaminoborane and sodium borohydride at a molar ratio of 3:2, dissolve them in water, and slowly pour them into the mixed solution (a) while stirring to obtain mixed solution (b). Mixed solution (b) contains: 30 g / L of metal salts (nickel sulfate, zinc sulfate), 3 g / L of dimethylaminoborane, 2 g / L of sodium borohydride, 3 g / L of sodium acetate, 7 g / L of sodium citrate, and 3 g / L of thiourea. Add deionized water to 1 L to obtain mixed solution (c). Place mixed solution (c) in an ultrasonic water bath and apply ultrasonic treatment at a frequency of 40 kHz to obtain a uniformly dispersed nanocomposite electroless nickel plating solution. Adjust the pH of the solution to 6 with acetic acid to obtain an acidic electroless nickel plating solution, and always keep the plating solution temperature at 50°C.
[0139] The remaining steps are the same as in Example 3.
[0140] Comparative Example 11
[0141] Same as Example 3, except that the chemical tube plating apparatus has been changed, and the specific setup method is as follows:
[0142] The pretreated B30 copper-nickel alloy tube is connected to both ends with flexible tubes (such as rubber tubes). The bottom inlet tube is connected to a porous distributor with a 2mm orifice. The tube is placed in an ultrasonic water bath filled with an acidic electroless nickel plating solution, and the temperature of the solution is maintained at 55℃. The top tube is connected to an ion pump to pump the acidic electroless nickel plating solution backflow through the B30 copper-nickel alloy tube. The solution is pumped in from the bottom of the tube (opposite to gravity), overflows from the top, and flows back through the top tube. The outlet section is equipped with a gradually expanding transition section with an expansion angle of 15° to form a stable laminar flow. The tube is then completely wrapped with rock wool for heat insulation. The acidic electroless nickel plating solution is slowly injected into the inner wall of the tube through the rubber tube at a flow rate of 1m / s, and ultrasonic plating at a frequency of 30kHz is applied for 1.5 hours. After plating, the tube is removed, rinsed with deionized water, and dried to obtain a self-sacrificing nanoparticle-reinforced B30 copper-nickel alloy tube.
[0143] The remaining steps are the same as in Example 3.
[0144] Comparative Example 12
[0145] Same as Example 3, except that the chemical tube plating apparatus has been changed, and the specific setup method is as follows:
[0146] The pretreated B30 copper-nickel alloy tube is connected to both ends with flexible tubes (such as rubber tubes). The bottom inlet tube is connected to a porous distributor with a 3mm orifice. The tube is placed in an ultrasonic water bath filled with an acidic electroless nickel plating solution, and the temperature of the solution is maintained at 55℃. The top tube is connected to an ion pump to pump the acidic electroless nickel plating solution backflow through the B30 copper-nickel alloy tube. The solution is pumped in from the bottom of the tube (opposite to gravity), overflows from the top, and flows back through the top tube. The outlet section has a gradually expanding transition section with an expansion angle of 15° to form a stable laminar flow. The tube is then completely wrapped with aluminum silicate fiber for heat insulation. The acidic electroless nickel plating solution is slowly injected into the inner wall of the tube through the rubber tube at a flow rate of 1.5m / s, and ultrasonic plating at a frequency of 30kHz is applied for 1.5 hours. After plating, the tube is removed, rinsed with deionized water, and dried to obtain a self-sacrificing nanoparticle-reinforced B30 copper-nickel alloy tube.
[0147] The remaining steps are the same as in Example 3.
[0148] XRD and SEM tests revealed that the average grain size of the nanocomposite coating in Example 3 was 64 nm, which is an order of magnitude finer than that of general coatings, but slightly coarser than that of the dual-nano rare earth oxide reinforcement system. Scratch tests were conducted at a sliding speed of 10 cm / s, a sliding distance of 200 m, and a pressure increasing from 0 to 100 N. The results showed that the failure pressure of the nanocomposite coating in Example 3 was significantly better than that of the nanocomposite coating in Comparative Example 9, which did not undergo only alkaline washing-acid washing pretreatment. This demonstrates that the alkaline washing-acid washing method proposed in this invention for B30 copper-nickel alloy pipes… The pretreatment process of chemical pickling and activation effectively improved the adhesion of the coating. Compared to Comparative Example 10, the coating in Example 3 showed no pores, reflecting the excellent influence of the dispersion state of nanoparticles in the acidic electroless nickel plating solution on the uniformity of the final coating. Compared to Comparative Examples 11 and 12, the coating in Example 3 had a more uniform cell distribution, indicating that increasing the flow rate can reduce pore formation to some extent compared to samples with lower flow rates. The coating cells were tightly bonded, essentially achieving full coverage of the inner wall of B30 pipes without significant defects. In the static water immersion test, Example 3 showed better protective performance than Comparative Example 10 without added nano-rare earth oxide particles, but its corrosion resistance was slightly lower than the dual nano-rare earth oxide reinforcement system. The coating in Example 3 was completely destroyed after 5 months, with no obvious corrosion on the exposed substrate, while the coating in Comparative Example 5 showed damage after 3 months. This demonstrates that the novel pipe-plating nickel-rare earth oxide composite coating process effectively improved the coating's lifespan and provided corrosion protection for B30 copper-nickel alloy pipes.
[0149] Comparative Example 13
[0150] A commonly used self-sacrificial anti-corrosion coating for metal sheets is prepared by the following steps:
[0151] (1) Same as Example 1, except that: B30 copper-nickel alloy pipes are not subjected to auxiliary ultrasonic process and alkaline washing-oxidation-acid washing-activation steps. Instead, they are directly cleaned by alkaline washing and soaking, acid washing and soaking, water washing and drying, and then set aside.
[0152] (2) Dissolve citric acid, glycine, nickel sulfate, and zinc sulfate in water and stir until homogeneous to obtain a mixed solution. Dissolve sodium hypophosphite in water and slowly pour it into the mixed solution while stirring. Finally, add lactic acid and stir until homogeneous. Add deionized water to 1L to obtain mixed solution (a). Mixed solution (a) contains: 35g / L nickel sulfate, 8g / L zinc sulfate, 25g / L sodium hypophosphite, 20g / L ammonium citrate, 15ml / L OP-emulsifier, and 10mL / L lactic acid. Adjust the pH of the solution to 8 with concentrated ammonia and heat the plating solution to 90℃.
[0153] (3) The B30 copper-nickel alloy pipe that has undergone the pretreatment in step (1) is placed in the mixed solution (a) for plating for 1.5 hours. After being taken out, rinsed with deionized water and dried, the commonly used self-sacrificing nickel-phosphorus-zinc layer B30 copper-nickel alloy pipe is obtained.
[0154] SEM images of the self-sacrificing nickel-phosphorus-zinc layer in the commonly used B30 copper-nickel alloy pipe prepared in Comparative Example 13 are shown below. Figure 3 .
[0155] XRD and SEM tests revealed that the average grain size of the self-sacrificing nickel-phosphorus-zinc layer in Comparative Example 10 was 200 nm, with large cell size, low coating density, and the presence of pores. Scratch tests were conducted at a sliding speed of 10 cm / s, a sliding distance of 200 m, and a pressure increasing from 0 to 100 N. The results showed that the failure pressure of the nickel-phosphorus-zinc layer was significantly lower than that of the coating in Example 1. In the static water immersion test for sealing pipes, the comparative coating was completely consumed within 30 days, and its anti-corrosion performance was far lower than that of the nanoparticle-reinforced coating in Example 1.
[0156] Comparative Example 14
[0157] A self-sacrificing anti-corrosion coating based on a commonly used multi-primary salt reducing agent system is prepared by the following steps:
[0158] (1) Same as Example 1, except that: B30 copper-nickel alloy pipes are not subjected to auxiliary ultrasonic process and alkaline washing-oxidation-acid washing-activation steps. Instead, they are directly cleaned by alkaline washing and soaking, acid washing and soaking, water washing and drying, and then set aside.
[0159] (2) Dissolve sodium acetate, ammonium citrate and thiourea in water and mix them evenly to obtain a mixed solution. Weigh nickel sulfate, copper sulfate and zinc sulfate in a molar ratio of 8:2:1 and mix them. Dissolve them in water and then slowly pour them into the mixed solution while stirring. Add deionized water to 1L to obtain mixed solution (a). Stir mixed solution (a) evenly and heat it to 85°C. Mix dimethylaminoborane and sodium borohydride in a molar ratio of 5:1. Dissolve them in water and then slowly pour them into mixed solution (a) while stirring to obtain mixed solution (b). Mixed solution (b) contains: 25g / L of metal salts (nickel sulfate, copper sulfate and zinc sulfate), 5g / L of dimethylaminoborane, 1g / L of sodium borohydride, 5g / L of sodium acetate, 5g / L of ammonium citrate, 3g / L of thiourea and 20mL / L of lactic acid. Adjust the pH of the solution to 6 with concentrated ammonia and heat the plating solution to 65°C.
[0160] (3) The B30 copper-nickel alloy pipe that has undergone the pretreatment in step (1) is placed in the mixed solution (b) for plating for 1.5 hours. After being taken out, rinsed with deionized water and dried, the self-sacrificing anti-corrosion coating of B30 copper-nickel alloy pipe with multi-main salt reducing agent system is obtained.
[0161] SEM images of the nickel-copper-zinc coating in the B30 copper-nickel alloy pipe prepared in Comparative Example 14 are shown below. Figure 3 .
[0162] XRD and SEM tests revealed that the average grain size of the self-sacrificing nickel-phosphorus-zinc layer in Comparative Example 14 was 157 nm, indicating large cell size and low coating density. Scratch tests were conducted at a sliding speed of 10 cm / s, a sliding distance of 200 m, and a pressure increasing from 0 to 100 N. The results showed that the failure pressure of the nickel-phosphorus-zinc layer was significantly lower than that of the coating in Example 1. In the static water immersion test for sealing pipes, the comparative coating was completely consumed within 60 days, and its anti-corrosion performance was far lower than that of the nanoparticle-reinforced coating in Example 1.
[0163] The embodiments described above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Various modifications and improvements made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.
Claims
1. A composite nickel plating solution, characterized in that: The composite nickel plating solution contains metal salts, reducing agents, complexing agents, nanoparticles, and stabilizers.
2. The composite nickel plating solution according to claim 1, characterized in that: The composite nickel plating solution contains a metal salt at a concentration of 25–30 g / L, a reducing agent at a concentration of 2–5 g / L, a complexing agent at a concentration of 5–10 g / L, nanoparticles at a concentration of 6–8 g / L, and a stabilizer at a concentration of 1–3 g / L.
3. The composite nickel plating solution according to claim 1 or 2, characterized in that: The metal salt is one or more of nickel sulfate, copper sulfate, and zinc sulfate; the reducing agent is a mixture of dimethylaminoborane and sodium borohydride; the complexing agent is a mixture of sodium citrate and sodium acetate; the stabilizer is thiourea; the nanoparticles are nano-rare earth oxides; and the nano-rare earth oxides are a mixture of two or more of nano-yttrium oxide, nano-lanthanum oxide, nano-samarium oxide, and nano-cerium oxide.
4. The method for preparing the composite nickel plating solution according to any one of claims 1 to 3, characterized in that: Includes the following steps: (1) Dissolve the complexing agent and stabilizer in water and mix them evenly to obtain a mixture. Dissolve the metal salt in water and then slowly pour it into the mixture while stirring to obtain a mixed solution (a). (2) Stir the mixed solution (a) until homogeneous and heat it to 50-60°C. Dissolve the reducing agent in water and slowly pour it into the mixed solution (a) while stirring to obtain the mixed solution (b). (3) Add the nanoparticles to the mixed solution (b) to obtain the mixed solution (c). Finally, dissolve 0.1 g / L SDS and 0.1 g / L SDBS in water and add them to the mixed solution (c) to obtain the mixed solution (d). Place the mixed solution (d) in an ultrasonic water bath at an ultrasonic frequency of 25-40 kHz to obtain a uniformly dispersed nanocomposite nickel plating solution. Adjust the pH value of the solution to 5-7 to obtain the composite nickel plating solution, and keep the temperature of the composite nickel plating solution at 50-60℃.
5. A B30 copper-nickel alloy pipe anti-corrosion coating, characterized in that: A nanoparticle-reinforced composite coating is formed on the inner wall of the B30 copper-nickel alloy tube using the composite nickel plating solution described in any one of claims 1 to 3 as an anti-corrosion coating.
6. A pipe plating process based on the B30 copper-nickel alloy pipe anti-corrosion coating as described in claim 5, characterized in that: The B30 copper-nickel alloy pipe is pretreated to remove surface oxides, and then a pipe plating device is used with ultrasonic treatment to uniformly plate a layer of nanoparticle-reinforced composite coating on the inner wall of the B30 copper-nickel alloy pipe with a composite nickel plating solution.
7. The tube plating process according to claim 6, characterized in that: The pretreatment process includes alkaline washing, oxidation, acid washing, and reduction activation; The alkaline solution used for the alkaline washing contains 10% to 15% NaOH and a surfactant. The surfactant is a mixture of two or more of the following: 0.1% SDS, 0.1% SDBS, 1 g / L C14-16 olefin sulfonate sodium, or 10 ml / LOP emulsifier. The treatment temperature is 50 to 60°C, and the solution is circulated and rinsed in a B30 copper-nickel alloy tube for 5 minutes. The oxidation solution used in the oxidation process contains 5% H2O2 and 3% citric acid solution, and is circulated and rinsed in a B30 copper-nickel alloy tube at room temperature for 15 minutes. The acidic solution used for pickling contains 15%–25% acetic acid and 20%–40% phosphoric acid. The treatment temperature is 50–60°C, and the solution is circulated and rinsed in a B30 copper-nickel alloy tube for 1–2 minutes. The activation solution used for reduction and activation contains 10% NaH2PO2 and 0.1 g / L PdCl2 solution. The solution has a pH of 8 and is treated at a temperature of 50-60°C. The solution is then left to stand in a B30 copper-nickel alloy tube for 1-2 minutes.
8. The tube plating process according to claim 7, characterized in that: During the alkaline washing, oxidation, and acid washing processes, the flow rate of the solution used is 0.1–5 m / s; during the alkaline washing and acid washing processes, the ultrasonic frequency is 25–40 kHz.
9. The tube plating process according to claim 6, characterized in that: The composite nickel plating solution is adjusted to pH 5-7 with acetic acid, the flow rate of the composite nickel plating solution is 0.1-1.5 m / s, the ultrasonic frequency is 15-40 kHz, the power is 150-180 W, and the plating time is 60-90 min at a temperature of 50-60℃.
10. The tube plating process according to claim 6 or 9, characterized in that: The tube plating device consists of hoses connected to both ends of a B30 copper-nickel alloy tube. A multi-hole distributor is connected to the bottom inlet of the hose, which is placed in an ultrasonic water bath filled with composite nickel plating solution. The top hose is connected to an ion pump that backflows the composite nickel plating solution through the B30 copper-nickel alloy tube. The composite nickel plating solution is pumped in from the bottom of the B30 copper-nickel alloy tube, overflows from the top, and flows back through the top hose, forming a stable laminar flow.