Method for in-situ growth of modified coating on B30 copper-nickel alloy

Abstract

The invention relates to the technical field of metal material surface treatment, in particular to a method for in-situ growth of a modified coating on a B30 copper-nickel alloy. The preparation method comprises the following steps: soaking B30 copper-nickel alloy in a layered double hydroxide growth solution, and reacting to obtain layered double hydroxide modified B30 copper-nickel alloy; the modified B30 copper-nickel alloy is soaked in a benzotriazole solution for a replacement reaction, and B30 copper-nickel alloy co-modified by benzotriazole and layered double hydroxide is obtained; the modified B30 copper-nickel alloy is soaked in a trimethylchlorosilane solution for super-hydrophobic treatment, and in-situ growth of a modified coating on the B30 copper-nickel alloy is completed; the LDHs-based anti-corrosion film prepared by the method has excellent anti-corrosion performance and self-repairing capability, and can still keep a good anti-corrosion effect after being soaked in a 3.5 wt% NaCl solution for 30 days.

Description

Technical Field

[0001] This invention relates to the field of surface treatment technology for metallic materials, and in particular to a method for in-situ growth of a modified coating on a B30 copper-nickel alloy. Background Technology

[0002] Copper and its alloys are widely used in many fields, but they are susceptible to corrosion in chloride-containing media. Traditional corrosion protection methods such as chromate passivation have been banned due to the high toxicity of chromates and environmental risks, while organic passivation films have limited performance due to their significant difference from the metal substrate.

[0003] Layered double hydroxides (LDHs) have attracted much attention in the field of corrosion protection due to their unique structure and properties. They have a layered structure and can achieve self-healing function through ion exchange. However, previous preparation methods have problems such as complex conditions and difficulty in tightly bonding with metal substrates. They are usually used as the main material rather than directly applied to metal substrates to prepare self-healing coatings.

[0004] Superhydrophobic surfaces, due to their unique microstructure and chemical composition, can effectively reduce liquid adhesion to the surface and minimize contact between corrosive media and metal surfaces, demonstrating great potential in the field of corrosion protection. Currently, various methods exist for preparing superhydrophobic surfaces, including chemical plating, sol-gel methods, and electrochemical deposition. However, combining superhydrophobic modification with the self-healing function of LDHs to achieve superior corrosion protection remains a research hotspot and challenge. Summary of the Invention

[0005] The purpose of this invention is to provide a method for in-situ growth of modified coatings on B30 copper-nickel alloys, in order to solve the problems of easy corrosion of copper alloys in chloride-containing media and traditional anti-corrosion methods, and to achieve superhydrophobic modification to further improve anti-corrosion capabilities.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for in-situ growth of a modified coating on a B30 copper-nickel alloy, comprising the following steps:

[0008] (1) B30 copper-nickel alloy was immersed in a layered double hydroxide growth solution to react and obtain layered double hydroxide modified B30 copper-nickel alloy.

[0009] (2) The B30 copper-nickel alloy modified with layered hydroxide was immersed in benzotriazole solution to carry out a displacement reaction, and a B30 copper-nickel alloy co-modified with benzotriazole and layered double hydroxide was obtained.

[0010] (3) The B30 copper-nickel alloy co-modified with benzotriazole and layered double hydroxide was immersed in trimethylchlorosilane solution for superhydrophobic treatment, and the in-situ modified coating was grown on the B30 copper-nickel alloy.

[0011] The layered double hydroxide growth solution is a mixed solution of aluminum source, sodium chloride, alkali source and water.

[0012] Optionally, the aluminum source comprises aluminum nitrate, and the concentration of the aluminum source in the layered double hydroxide growth solution is 0.01–0.1 mol / L.

[0013] Optionally, the concentration of sodium chloride in the layered double hydroxide growth solution is 3-6 wt%.

[0014] Optionally, the alkali source includes urea or ammonia.

[0015] Optionally, the concentration of the alkaline source in the layered double hydroxide growth solution is 0.5–1.5 mol / L.

[0016] Optionally, the reaction temperature in step (1) is 100-150°C and the time is 5-10 hours.

[0017] Optionally, the concentration of the benzotriazole solution is 0.01–0.5 mol / L.

[0018] Optionally, the temperature of the displacement reaction in step (2) is 15–30°C and the time is 5–10 h.

[0019] Optionally, the concentration of the trimethylchlorosilane solution is 0.3–0.8 mol / L.

[0020] Optionally, the temperature of the superhydrophobic treatment in step (3) is 50-80℃ and the time is 1-3h.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] By in-situ growing CuNiAl ternary LDHs nanofilms and utilizing their interlayer anion exchange properties, Cl... - Ion substitution of BTA- enables self-healing. Simultaneously, superhydrophobic treatment imparts low surface energy and a unique microstructure to the coating surface, effectively reducing the adhesion of water and corrosive media, further enhancing the coating's anti-corrosion performance. The LDHs-based anti-corrosion film prepared by this method exhibits excellent anti-corrosion performance and self-healing ability, maintaining good anti-corrosion effects even after immersion in a 3.5 wt% NaCl solution for 30 days. Attached Figure Description

[0023] Figure 1This is a flowchart illustrating the in-situ growth of a modified coating on a B30 copper-nickel alloy according to the present invention.

[0024] Figure 2 SEM images of the products prepared in Example 1 and Comparative Example 2, wherein (a) and (b) are the products of Example 1; and (c) and (d) are the products of Comparative Example 2.

[0025] Figure 3 Contact angle test diagrams of the products prepared in Example 1 and Comparative Example 1;

[0026] Figure 4 XRD patterns of the products prepared in Example 1 and Comparative Example 1;

[0027] Figure 5 FTIR characterization images of the products prepared in Example 1 and Comparative Example 1;

[0028] Figure 6 OCP plots were obtained for samples at different soaking times: (a) soaking for 4 days; (b) soaking for 8 days; (c) soaking for 16 days; (d) soaking for 32 days.

[0029] Figure 7 Nyquest and Bode plots of samples from each group soaked for 4 days;

[0030] Figure 8 Nyquest and Bode plots of samples from each group soaked for 8 days;

[0031] Figure 9 Nyquest and Bode plots of samples from each group after soaking for 16 days;

[0032] Figure 10 Nyquest and Bode plots for each group of samples soaked for 32 days. Detailed Implementation

[0033] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0034] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0035] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0036] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0037] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0038] All raw materials used in this invention can be obtained commercially or prepared using existing technologies.

[0039] The ambient temperature described in this invention is 15–30°C.

[0040] This invention provides a method for in-situ growth of a modified coating on a B30 copper-nickel alloy, comprising the following steps:

[0041] (1) B30 copper-nickel alloy was immersed in a layered double hydroxide growth solution to react and obtain layered double hydroxide modified B30 copper-nickel alloy.

[0042] (2) The B30 copper-nickel alloy modified with layered hydroxide was immersed in benzotriazole solution to carry out a displacement reaction, and a B30 copper-nickel alloy co-modified with benzotriazole and layered double hydroxide was obtained.

[0043] (3) The B30 copper-nickel alloy co-modified with benzotriazole and layered double hydroxide was immersed in trimethylchlorosilane solution for superhydrophobic treatment, and the in-situ modified coating was grown on the B30 copper-nickel alloy.

[0044] In this invention, the B30 copper-nickel alloy needs to be pretreated before use. In an embodiment of this invention, the specific method of pretreatment is as follows: the B30 copper-nickel alloy is immersed in a solution of nitric acid and water in a 1:1 ratio, and etched at room temperature for 2 minutes to remove the passivation layer on the surface of the B30 copper-nickel alloy.

[0045] Step (1) involves immersing the B30 copper-nickel alloy in a layered double hydroxide growth solution, where Cu and Ni act as copper and nickel sources, respectively, reacting with the aluminum source to obtain a layered double hydroxide-modified B30 copper-nickel alloy (LDHs-CO3). 2- Nanosheets);

[0046] In this invention, the layered double hydroxide growth solution is a mixed solution of aluminum source, sodium chloride, alkali source and water.

[0047] In an embodiment of the present invention, a layered double hydroxide growth solution is prepared by uniformly mixing an aluminum source, sodium chloride, an alkali source, and deionized water.

[0048] In this invention, the aluminum source comprises aluminum nitrate; in an embodiment of this invention, the aluminum nitrate is aluminum nitrate nonahydrate.

[0049] The concentration of the aluminum source in the layered double hydroxide growth solution is 0.01–0.1 mol / L, for example, it can be 0.01 mol / L, 0.02 mol / L, 0.04 mol / L, 0.08 mol / L or 0.1 mol / L, etc.

[0050] In this invention, the concentration of sodium chloride in the layered double hydroxide growth solution is 3-6 wt%, for example, it can be 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, or 6 wt%.

[0051] In this invention, the alkaline source includes urea or ammonia, preferably urea; the concentration of the alkaline source in the layered double hydroxide growth solution is 0.5 to 1.5 mol / L, for example, it can be 0.5 mol / L, 0.9 mol / L, 1 mol / L, 1.1 mol / L, 1.2 mol / L, 1.4 mol / L or 1.5 mol / L, etc.

[0052] In this invention, the urea or ammonia water serves as a slow-release OH solution. - The source provides an alkaline environment for the growth of LDH.

[0053] In this invention, the reaction temperature in step (1) is 100-150°C, for example, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C; the time is 5-10h, for example, 5h, 6h, 7h, 8h, 9h or 10h.

[0054] In this invention, copper in the B30 copper-nickel alloy is used as the copper source, nickel is used as the nickel source, and they react together with aluminum to grow LDH in situ on the B30 copper-nickel alloy. The LDH can be tightly bonded to the metal matrix.

[0055] Step (2) involves rinsing the layered double hydroxide-modified B30 copper-nickel alloy with decarbonated water, and then immersing it in a benzotriazole solution to allow the BTA to precipitate. - Displace CO3 between LDH layers 2- A B30 copper-nickel alloy (LDHs-BTA) co-modified with benzotriazole and layered double hydroxides was obtained. - Nanosheets);

[0056] In this invention, the concentration of the benzotriazole solution is 0.01 to 0.5 mol / L, for example, it can be 0.01 mol / L, 0.1 mol / L, 0.2 mol / L, 0.3 mol / L, 0.4 mol / L or 0.5 mol / L, etc.

[0057] In this invention, the temperature of the displacement reaction in step (2) is 15 to 30°C, for example, 15°C, 20°C, 25°C or 30°C; the time is 5 to 10 hours, for example, 5 hours, 6 hours, 7 hours, 8 hours, 9 hours or 10 hours.

[0058] In this invention, an alkaline environment accelerates CO2 absorption, and due to its high charge density and small volume, it preferentially intercalates into the LDH interlayer, allowing CO3 to be absorbed more readily. 2- The high interlayer stability of LDH leads to the formation of carbonate ions in the interlayer. Decarbonated water is then used to flush LDHs-CO3. 2- Nanosheets can remove carbonate ions between the layers of layered double hydroxides, allowing benzotriazole to insert more easily.

[0059] Step (3) involves immersing the B30 copper-nickel alloy co-modified with benzotriazole and layered double hydroxides in a trimethylchlorosilane solution for superhydrophobic treatment, followed by drying, to complete the in-situ growth of the modified coating on the B30 copper-nickel alloy (forming LDHs-BTA). - (Superhydrophobic nanosheets).

[0060] In this invention, the concentration of the trimethylchlorosilane solution is 0.3 to 0.8 mol / L, for example, it can be 0.3 mol / L, 0.4 mol / L, 0.5 mol / L, 0.6 mol / L, 0.7 mol / L or 0.8 mol / L, etc.

[0061] In this invention, the temperature of the superhydrophobic treatment in step (3) is 50 to 80°C, for example, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C or 80°C; the time is 1 to 3 hours, for example, 1 hour, 2 hours or 3 hours; the drying temperature is 60°C and the time is 2 hours.

[0062] The technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0063] In an embodiment of the present invention, the B30 copper-nickel alloy contains 70 wt% Cu and 30 wt% Ni;

[0064] The dimensions of B30 copper-nickel alloy are 10mm × 10mm × 4mm (length × width × height);

[0065] Before surface modification, B30 copper-nickel alloy needs to undergo pretreatment. Specifically, the B30 copper-nickel alloy is immersed in a solution of nitric acid and water in a 1:1 ratio and etched at room temperature for 2 minutes to remove the passivation layer on the surface of the B30 copper-nickel alloy.

[0066] Example 1

[0067] (1) A layered double hydroxide growth solution was obtained by mixing 100 ml of 0.1 mol / L aluminum nitrate nonahydrate solution, 100 ml of 5 wt% sodium chloride solution, and 100 ml of 1 mol / L urea solution. B30 copper-nickel alloy was immersed in the layered double hydroxide growth solution and reacted at 120℃ for 8 h to obtain layered double hydroxide modified B30 copper-nickel alloy (LDHs-CO3). 2- Nanosheets);

[0068] (2) The B30 copper-nickel alloy modified with layered double hydroxides was rinsed with decarbonated water and then immersed in a 0.5 mol / L benzotriazole solution (BTA) for 6 h at room temperature to obtain a B30 copper-nickel alloy co-modified with benzotriazole and layered double hydroxides (LDHs-BTA). - Nanosheets);

[0069] (3) The B30 copper-nickel alloy co-modified with benzotriazole and layered double hydroxides was immersed in a 0.5 mol / L trimethylchlorosilane solution (TMCS) and reacted at 60 °C for 2 h. After the reaction was completed, it was dried at 60 °C for 2 h to complete the in-situ growth of the modified coating (LDHs-BTA) on the B30 copper-nickel alloy. - (Superhydrophobic nanosheets).

[0070] Comparative Example 1

[0071] The only difference from Example 1 is that the B30 copper-nickel alloy co-modified with benzotriazole and layered double hydroxides is not subjected to hydrophobic treatment, and is designated as LDHs-BTA. - Nanosheets.

[0072] Comparative Example 2

[0073] A layered double hydroxide growth solution was prepared by mixing 100 ml of 0.1 mol / L aluminum nitrate nonahydrate solution, 100 ml of 5.0 wt% sodium chloride solution, and 100 ml of 1 mol / L urea solution. B30 copper-nickel alloy was then immersed in the layered double hydroxide growth solution and reacted at 120 °C for 8 h to obtain a layered double hydroxide modified B30 copper-nickel alloy (LDHs-CO3). 2- Nanosheets).

[0074] Test case

[0075] SEM images of the products prepared in Example 1 and Comparative Example 2 are shown below. Figure 2 As shown, by Figure 2 Analysis of the provided scanning electron microscope (SEM) images reveals that hydrophobic surface modification significantly alters the microstructure and morphology of layered double hydroxides (LDHs). In the surface-modified samples (Figures a and b), the material exhibits a three-dimensional porous network structure. Figure (a), at 10,000x magnification, shows densely distributed mesopores and macropores (approximately 5 μm in diameter), forming interconnected channels. Figure (b), at 40,000x magnification, clearly shows ultrathin nanosheets (thickness < 100 nm) constituting the network, with curled edges, collectively constructing a hierarchical rough surface at both the micro and nanoscales. This morphology originates from the regulation of LDH crystal growth by hydrophobic modifiers (such as long-chain alkylsilanes): the modifiers selectively adsorb onto the {001} crystal plane, inhibiting one-dimensional growth and instead inducing the formation of two-dimensional nanosheets. Furthermore, the self-assembly forces between hydrophobic groups drive the interleaved stacking of the sheets, forming a thermodynamically stable porous framework. The structural transformation, combined with surface chemical modification, significantly reduces the surface energy of the material. At the same time, the hierarchical rough surface effectively traps air (Cassie-Baxter state), which together endows the material with superhydrophobic properties (theoretical contact angle > 150°) and improves its mass transfer efficiency and mechanical stability in applications such as oil-water separation.

[0076] In contrast, the unmodified raw LDH samples (Figures c and d) exhibit a disordered, aggregated micron-sized fibrous structure (diameter > 500 nm) under 5000x magnification. The fiber surfaces are smooth and densely packed, resulting in poor pore connectivity. This morphology stems from the inherent crystal growth habit of LDH—preferential growth along the

[001] direction to form high aspect ratio fibers. The unmodified high surface energy surface and dense structure make it hydrophilic (contact angle < 90°), and the internal closed-pore structure hinders material diffusion, limiting its functional applications. Therefore, hydrophobic modification, through a cascade effect of chemical composition regulation → crystallization kinetics alteration → multi-level structure construction, achieves morphological reconstruction of LDH from a disordered fibrous state to a porous layered network, providing a key structural foundation for designing high-performance LDH-based functional materials.

[0077] The contact angles of the products prepared in Example 1 and Comparative Example 1 were tested, and the test results are as follows: Figure 3 As shown, by Figure 3 The figure clearly shows the decisive influence of surface modification on the wettability of layered bimetallic hydroxides (LDHs): (a) The droplets on the unmodified LDH surface in the figure show an obvious flat spreading morphology (contact angle of about 77°), confirming the intrinsic hydrophilicity of the material. This is due to the strong hydrogen bonding between the exposed polar hydroxyl groups (-OH) on the LDH surface and water molecules. In addition, the micron-scale fibrous structure shown by SEM leads to high surface energy exposure, which together drive the droplet wetting; (b) The LDHs modified with hydrophobic surface in the figure show a near-spherical droplet state (contact angle > 150°). This superhydrophobicity is due to the synergistic effect of two mechanisms - the chemical modification layer (such as long-chain silane) covers the hydroxyl groups, reducing the surface energy to 20-30 mN / m. At the same time, the nanosheet curling and porous network observed by SEM construct a hierarchical rough structure, forcing the droplet to be suspended on an air pad (Cassie-Baxter state). The actual solid-liquid contact area is less than 5%. This wettability transformation indicates that surface modification, by passivating polar sites and constructing micro- and nano-roughness, successfully transforms LDHs from hydrophilic carriers into functional materials with self-cleaning, corrosion resistance, and oil-water separation potential.

[0078] Figure 4 These are the XRD patterns of the products prepared in Example 1 and Comparative Example 1, by... Figure 4 The image shows XRD patterns and corresponding diffraction peak data. In the left-hand spectrum, the upper red curve (marked as 1-BTA) represents unmodified LDHs, and the lower red curve (4-TMCS) represents LDHs modified with TMCS. Both were accurately analyzed using background subtraction (blue curve BackSub). The table on the right provides quantitative data for key diffraction peaks, including 2θ values, relative intensities, full width at half maximum (FWHM), d-spacing, and Scherrer width (a parameter used to calculate grain size). Overall, the comparison shows that hydrophobic modification with TMCS significantly alters the crystal structure characteristics of LDHs.

[0079] In the XRD pattern of unmodified LDHs (1-BTA), characteristic peaks are clear and have high intensity, such as the diffraction peaks at 19.56° (intensity 6384.63), 43.42° (13376.58), and 72.16° (60518.56). These correspond to the typical layered structure characteristic crystal planes of LDHs (such as (003), (101), and (110) crystal planes). The interplanar spacing data (such as d = 0.4535 nm at 19.56°) are consistent with the inherent high crystallinity and regular interlayer stacking of LDHs, indicating that the material has an ordered crystal structure, which is beneficial for high surface energy and hydrophilicity. This is consistent with the aforementioned hydrophilic angle test results (contact angle 77°).

[0080] In contrast, the XRD pattern of TMCS-modified (4-TMCS) showed significant changes: the intensity of characteristic diffraction peaks generally decreased (e.g., the intensity at 72.20° increased to 88606.22, but the intensity of key peaks such as at 43.46° decreased from 13376.58 to 10516.55, and the characteristic peak at 19.56° almost disappeared), and the peak shape also broadened slightly, reflecting a decrease in crystal order. This is due to the silanization modification process of the TMCS molecule: trimethylchlorosilane ((CH3)3SiCl) is bonded to the surface of LDHs through a hydrolysis-condensation reaction, replacing some of the surface hydroxyl groups (-OH) to form a hydrophobic trimethylsilyl [-Si(CH3)3] layer. This chemical modification disrupts the integrity of the original crystal lattice for several reasons, including: Chemical bonding-induced structural perturbation: TMCS molecules embed into the interlayer or surface sites of LDHs, increasing lattice distortion and disorder, leading to weakened or even absent intensity of some diffraction peaks (e.g., the disappearance of the 19.56° peak), manifesting as increased crystal defects. Grain size changes: Grain size calculated using the Scherrer equation (D = Kλ / βcosθ) shows a slight increase (e.g., the FWHM at 49.30° decreases slightly from 0.320° to 0.300°, corresponding to a Scherrer width increase from 27.31 nm to 29.14 nm), indicating that the modification may slightly coarsen the surface grains, but the overall crystallinity decreases, reflected in an overall reduction in peak intensity and changes in full width at half maximum (FWHM). Layered structure effects: Interplanar spacing (e.g., d ≈ 0.208 nm at 43.42° and 43.46°) remains relatively stable, but the decrease in diffraction intensity and peak broadening reveal the disruption of interlayer order caused by hydrophobic modification. This is because the hydrophobic groups of TMCS form an organic layer on the surface of LDHs, increasing structural heterogeneity. This is consistent with the lamellar curling and porous network formation observed by SEM, but XRD confirms its effect at the atomic scale: surface modification reduces surface energy (corresponding to a hydrophobic angle > 150°) while perturbing the long-range order of the crystal.

[0081] From a materials science perspective, this XRD change reveals the core mechanism of TMCS hydrophobic modification: it achieves a wettability transformation through surface chemical bonding rather than bulk structural alteration—introducing surface disorder and defects to reduce crystallinity and adapt to hydrophobicity without significantly changing lattice parameters (d-spacing stability). Therefore, although the modified LDHs exhibit slight structural damage, the synergistic micro- and nano-roughness (as shown in SEM) forms a superhydrophobic surface, enhancing its potential for applications such as oil-water separation and corrosion protection.

[0082] Figure 5 These are FTIR characterization patterns of the products prepared in Example 1 and Comparative Example 1, by... Figure 5 It can be seen that in the unmodified LDHs (bta spectrum), 3445 cm⁻¹ -1The strong, broad peak (transmittance 0.24) clearly shows the characteristic stretching vibrations of the hydroxyl (-OH) groups and adsorbed water in the laminations, confirming the intrinsic hydrophilicity of the material; 1380 cm⁻¹ -1 With 1070cm -1 The peaks (transmittances of 0.18 and 0.12, respectively) are attributed to the bending vibrations of interlayer carbonate ions (ν(CO)) and OH groups, while the peaks at 550–600 cm⁻¹ are attributed to these vibrations. -1 Range (e.g., 551cm) -1 The vibrational peak of the transmittance (0.12) originates from the metal-oxygen bond (ν(MO) / δ_(OMO)), which together constitute the hydroxylated surface and carbonate intercalation structure of the original LDHs.

[0083] After TMCS modification (TMCS-Process spectrum), significant evidence of chemical bonding is evident: 3445 cm⁻¹ -1 The transmittance of the hydroxyl peak increased to 0.45, and its intensity weakened significantly, confirming that the surface -OH groups were replaced by silane; at the same time, the newly formed characteristic peak directly points to the hydrophobic group grafting—2929 cm⁻¹. -1 With 2880cm -1 The CH stretching vibration peak (transmittance 0.25 / 0.20) corresponds to the ν(as) / ν(s) of the methyl group (-CH3), and its intensity is twice that of the unmodified state, revealing a dense methyl layer covering; 1270 cm⁻¹ -1 The peak (transmittance 0.2) is attributed to the Si-CH3 bending vibration, 831 cm⁻¹. -1 The peak (transmittance 0.1) reflects Si-C bond stretching, both of which are hallmark signals of TMCS modification. Furthermore, at 465 cm⁻¹... -1 Out-of-plane bending vibration at Si-O-Si (transmittance 0.18) and 1060–1100 cm⁻¹ -1 The widened range suggests the formation of a silicon-oxygen network, while 2152 cm⁻¹ -1 The weak peak (transmittance 0.05) may originate from residual Si-H byproducts.

[0084] The above changes originate from the TMCS hydrolysis-condensation reaction: LDHs-OH+(CH3)3SiCl→LDHs-O-Si(CH3)3+HCl. This process constructs a covalently bonded ≡Si-OM interface on the LDHs surface through nucleophilic substitution, simultaneously achieving hydroxyl passivation (inhibiting hydrogen bonding) and the introduction of a low surface energy methyl layer (reducing the surface energy to 20–30 mN / m). Combined with the micro-nano rough structure observed by SEM, this ultimately drives the material to transform from a hydrophilic state (contact angle 77°) to a superhydrophobic state (contact angle >150°), laying the chemical foundation for oil-water separation and self-cleaning applications.

[0085] Based on time-varying analysis of four sets of electrochemical impedance spectroscopy (EIS) data, combined with open-circuit potential (OCP) data and sample modification processes, the corrosion resistance of three B30 copper-nickel alloys was comprehensively evaluated. The corrosion behavior of the three modified samples was tracked through a 32-day immersion cycle: Sample A (LDH / BTA / hydrophobic triple modification, experimental group 1), Sample B (LDH / BTA dual composite, control group 1), and Sample C (single LDH layer, control group 2). The test results are as follows: Figures 6-10 As shown, by Figures 6-10 As can be seen from the open-circuit potential test, sample A always maintains the most negative potential (approximately -0.22V to -0.18V), indicating that it has the lowest thermodynamic corrosion tendency, while sample C has the highest potential (approximately -0.10V to -0.06V), indicating that it has the weakest electrochemical stability.

[0086] Electrochemical impedance spectroscopy (EIS) revealed the evolution of the interfacial protection mechanism. During short-term immersion (4 days), sample C exhibited a 35° peak in the phase angle curve due to LDH passivation, but its response range was narrow (<1 Hz), suggesting the fragility of the passivation film. Sample A, while showing a lower phase angle (25°), already exhibited broadband response characteristics. With the immersion time extended to 32 days, the peak phase angle of sample A jumped to 48°, and the bandwidth expanded to the 0.1-10 Hz range, demonstrating that the synergistic effect of the hydrophobic modification layer and the BTA intercalation formed a dense and electrochemically stable protective interface. This system significantly improved charge transfer resistance by blocking water and oxygen permeation and delaying corrosion inhibitor loss (as shown by the continuous expansion of the capacitive arc radius in the Nyquist plot). In contrast, the peak phase angle of sample B (42-45°) was consistently lower than that of sample A, and the peak width of the phase angle was narrower, reflecting that the unsealed LDH microporous structure still allowed the medium to slowly permeate; the phase angle of sample C decayed to 40-42°, and its initial passivation advantage was completely lost due to the collapse of the layered structure caused by OH- erosion during long-term immersion.

[0087] Impedance modulus data further corroborate the above conclusions. Although sample C exhibits the highest low-frequency impedance modulus (|Z|≈3.4Ω) at 32 days, its narrow phase angle response reveals that this originates from a brittle passivation film rather than an effective protective layer. Sample A, while having a moderate low-frequency impedance (|Z|≈1.2Ω), exhibits a kinetic synergy with its continuously increasing phase angle—the hydrophobic layer suppresses interfacial charge transfer processes through physical barrier action, resulting in a stable and controllable corrosion rate. Sample B's impedance behavior falls between the two, indicating that BTA intercalation can provide partial corrosion inhibition, but the lack of a hydrophobic sealing layer limits its long-term protective capability.

[0088] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method of growing a modified coating in situ on a B30 copper-nickel alloy, characterized by, The method comprises the following steps: (1) soaking the B30 copper-nickel alloy in a layered double hydroxide growth solution to react, to obtain a layered double hydroxide modified B30 copper-nickel alloy; (2) soaking the layered double hydroxide modified B30 copper-nickel alloy in a benzotriazole solution to perform a displacement reaction, to obtain a benzotriazole and layered double hydroxide co-modified B30 copper-nickel alloy; (3) soaking the benzotriazole and layered double hydroxide co-modified B30 copper-nickel alloy in a trimethylchlorosilane solution to perform a super-hydrophobic treatment, to complete in-situ growth of a modified coating on the B30 copper-nickel alloy. The layered double hydroxide growth solution is a mixed solution of an aluminum source, sodium chloride, an alkali source and water.

2. The method of claim 1, wherein, The aluminum source comprises aluminum nitrate, and the concentration of the aluminum source in the layered double hydroxide growth solution is 0.01-0.1 mol / L.

3. The method of claim 1, wherein, The concentration of sodium chloride in the layered double hydroxide growth solution is 3-6 wt%.

4. The method of claim 1, wherein, The alkali source comprises urea or ammonia water.

5. The method of claim 1, wherein, The concentration of the alkali source in the layered double hydroxide growth solution is 0.5-1.5 mol / L.

6. The method of claim 1, wherein, The temperature of the reaction in step (1) is 100-150 ℃, and the time is 5-10 h.

7. The method of claim 1, wherein, The concentration of the benzotriazole solution is 0.01-0.5 mol / L.

8. The method of claim 1, wherein, The temperature of the displacement reaction in step (2) is 15-30 ℃, and the time is 5-10 h.

9. The method of claim 1, wherein, The concentration of the trimethylchlorosilane solution is 0.3-0.8 mol / L.

10. The method of claim 1, wherein, The temperature of the super-hydrophobic treatment in step (3) is 50-80 ℃, and the time is 1-3 h.

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