Stainless steel passive film for ship accessories and preparation method of stainless steel passive film

Abstract

The invention relates to the technical field of ship protection materials, in particular to a ship accessory stainless steel passive film and a preparation method thereof.The passive film comprises 4-6 parts of a multifunctional nano composite material and 3-5 parts of an electrochromic-anti-corrosion bifunctional material, the multifunctional nano composite material comprises nano particles compounded by ZnO / ZnFe2O4 heterojunction and Ti < 3 > C < 2 > T < x > / MXene, and the electrochromic-anti-corrosion bifunctional material is PANI (at) CsxWO3 core-shell microspheres formed by polyaniline wrapping CsxWO3; 1-2 parts of a bionic enhancing component comprising a polydopamine coating and a nano cellulose crystal; 2-3 parts of a corrosion inhibitor carrier which is a phytic acid modified ZrO2 nano-cluster; 2-4 parts of a silane coupling agent; 0.5-1.5 parts of a dispersion stabilizer, which is prepared from sodium carboxymethyl cellulose and an amphiphilic block copolymer; and 0.2-0.6 part of a conductive reinforcing agent is a mixture of carbon nanotubes and graphene quantum dots, which are treated by an ultrasonic-microwave synergistic stripping method.

Description

Technical Field

[0001] The present invention relates to the technical field of ship protection materials, and particularly to a stainless steel passivation film for ship fittings and a preparation method thereof. Background Art

[0002] Ships are in a harsh marine environment with high salinity, high humidity and alternating wet and dry conditions for a long time, and their protective coatings need to meet multiple requirements such as corrosion resistance, anti-biofouling, anti-mechanical impact and rapid repair at the same time.

[0003] In modern industry, stainless steel is widely used in various fields due to its excellent corrosion resistance, high strength and beautiful appearance, especially in the manufacture of ship fittings. However, even though stainless steel itself has good corrosion resistance, in extreme environments such as the marine environment with high salinity, high humidity and strong ultraviolet radiation, additional protection measures are still required to extend its service life and ensure the safety and reliability of equipment.

[0004] Traditional stainless steel passivation treatment usually uses passivators containing chromates or dichromates to form a protective film. This passivation film can improve the corrosion resistance of the stainless steel surface to a certain extent, but has the following deficiencies:

[0005] Environmental pollution problem: Chromates and dichromates belong to heavy metal compounds, and a large amount of harmful wastewater will be generated during their production and use, causing serious pollution to the environment, and these substances also have potential hazards to human health.

[0006] Limited durability: Although traditional passivation films can provide a certain degree of anti-corrosion effect in the short term, when exposed to harsh environments for a long time, their protective ability will gradually weaken, resulting in pitting corrosion or other forms of corrosion on the metal surface.

[0007] Single function limitation: Traditional passivation films mainly focus on improving the corrosion resistance of materials, but perform poorly in terms of wear resistance and anti-ultraviolet aging. For ship fittings, in addition to facing the erosion of seawater, they also need to withstand mechanical wear and strong sunlight irradiation, which puts higher requirements on the passivation film.

[0008] Lack of real-time monitoring means: At present, most passivation films do not have self-detection or early warning functions. Once local corrosion occurs, it is often difficult to detect and handle in time, increasing the maintenance cost and risk.

[0009] In the manufacturing process of ship fittings, traditional stainless steel passivators are often difficult to meet the requirements of high corrosion resistance, good adhesion and chemical stability at the same time. Especially in the marine environment with high salinity, high humidity and strong ultraviolet radiation, ordinary passivation films are prone to failure, resulting in corrosion of the metal surface and affecting the service life and safety of equipment. Summary of the Invention

[0010] Aiming at the deficiencies of the prior art, the present invention provides a stainless steel passivation film for ship fittings and a preparation method thereof. The passivation film has excellent corrosion resistance, wear resistance and ultraviolet resistance, and is particularly suitable for application scenarios with extremely high requirements for weather resistance and corrosion resistance in marine environments.

[0011] According to the first aspect of the present invention, a stainless steel passivation film for ship fittings is provided, which is prepared from the following components and parts by weight:

[0012] 4-6 parts of multifunctional nanocomposite material (MNC): including nanoparticles composed of ZnO / ZnFe2O4 heterojunction and Ti3C2Tx / MXene composite,

[0013] 3-5 parts of electrochromic-anticorrosion bifunctional material: PANI@Cs x WO3 (cesium tungstate) formed by wrapping Cs x WO3 core-shell microspheres, wherein Cs x WO3 accounts for 15-30% of the total mass of the PANI@Cs x WO3 core-shell microspheres;

[0014] 1-2 parts of bionic reinforcement component: including polydopamine (PDA) coating and nanocrystalline cellulose (NCC), wherein the mass ratio of the polydopamine (PDA) coating to the nanocrystalline cellulose (NCC) is (1:1)-(2:1);

[0015] 2-3 parts of corrosion inhibitor carrier: phytic acid-modified ZrO2 nanoclusters, wherein the chelation molar ratio of phytic acid to ZrO2 is (1:1)-(1:2);

[0016] 2-4 parts of silane coupling agent: selected from γ-aminopropyltriethoxysilane or γ-(2,3-epoxypropoxy)propyltrimethoxysilane;

[0017] 0.5-1.5 parts of dispersion stabilizer: including sodium carboxymethylcellulose (CMC-Na) and amphiphilic block copolymer PS-b-PAA, and the mass ratio of the sodium carboxymethylcellulose (CMC-Na) to the amphiphilic block copolymer (PS-b-PAA) is (3:1)-(5:1);

[0018] 0.2-0.6 parts of conductive enhancer: a mixture of carbon nanotubes and graphene quantum dots (GQDs) treated by ultrasonic-microwave synergistic exfoliation method, and the mass ratio of the carbon nanotubes to the graphene quantum dots (GQDs) is (1:2)-(2:1);

[0019] The balance is deionized water.

[0020] Multifunctional Nanocomposite (MNC): ZnO / ZnFe2O4@Ti3C2Tx / MXene / MoS2 Quantum Dot System:

[0021] The multifunctional nanocomposite (MNC) used in this invention consists of ZnO (wide-bandgap semiconductor), ZnFe2O4 (narrow-bandgap semiconductor), Ti3C2Tx / MXene coating layer, and MoS2 quantum dots. By precisely regulating the energy band structure and interfacial coupling relationship between the components, a type-II heterojunction structure with efficient charge separation ability is constructed.

[0022] ZnO / ZnFe2O4 Heterojunction Design:

[0023] ZnO has a relatively wide bandgap (~3.37 eV) and excellent photocatalytic activity; while ZnFe2O4 is a p-type magnetic semiconductor with a bandgap of about 1.9 eV. A type-II heterojunction is formed in their energy band structures, enabling electrons to migrate from ZnFe2O4 to the conduction band of ZnO under light excitation, while holes remain in the valence band of ZnFe2O4.

[0024] This spatial charge separation mechanism significantly improves the lifetime and separation efficiency of photo-generated carriers. Through ultraviolet-visible diffuse reflectance spectroscopy (UV-Vis DRS) testing, it shows that the separation efficiency of photo-generated electron-hole pairs in this heterojunction system can reach over 78% under simulated sunlight irradiation, thus achieving efficient degradation of organic pollutants (degradation rate > 90%) and endowing the passivation film with excellent self-cleaning performance.

[0025] Magnetic Auxiliary Function of ZnFe2O4:

[0026] ZnFe2O4 has a good saturation magnetization (about 35 emu / g), which can effectively adsorb Fe 3+ ions released during the corrosion process, reduce the metal dissolution in the local anodic area, inhibit pitting initiation, and improve the stability and repair ability of the passivation film.

[0027] Function of Ti3C2Tx / MXene Coating Layer:

[0028] Ti3C2Tx / MXene is a two-dimensional transition metal carbide with excellent electrical conductivity (≈6000 S / cm) and chemical stability. It coats the surface of ZnO / ZnFe2O4 in the form of flakes, not only serving as an efficient electron transport channel to accelerate the charge transfer process at the heterojunction interface, but also effectively inhibiting the photo-corrosion behavior of ZnO under light conditions.

[0029] Meanwhile, through the surface modification with octadecyltrichlorosilane, MXene exhibits hydrophobic characteristics (water contact angle ≥ 110°), significantly reducing the wettability of seawater on the passivation film. The contact angle hysteresis is less than 5°, thereby enhancing the moisture resistance of the material in the marine environment.

[0030] Mechanism of MoS2 quantum dot doping:

[0031] MoS2 quantum dots are uniformly distributed on the surface of the heterojunction. It is rich in sulfur vacancies, and these defect sites can serve as the capture centers for Cl- ions. XPS analysis confirms that the binding energy of the S2p orbital in MoS2 shifts by 1.2 eV, indicating an obvious change in the electronic state, further verifying the existence of sulfur vacancies and their strong adsorption ability for Cl-.

[0032] This mechanism effectively delays the pitting initiation process induced by Cl- and enhances the long-term stability of the passivation film at high chloride ion concentrations.

[0033] Electrochromic-anticorrosion bifunctional material: PANI@Cs x WO3 core-shell microspheres:

[0034] In this invention, a core-shell structure microsphere formed by wrapping cesium tungstate (Cs x WO3) with polyaniline (PANI) is innovatively introduced, which has both excellent anticorrosion performance and real-time corrosion visualization monitoring function.

[0035] Redox activity of the PANI shell:

[0036] PANI exists in the form of Emeraldine salt and has a high conductivity (10 -1 S / cm). Its redox characteristics can promote the transformation of Fe 2+ to Fe 3+ on the stainless steel surface and assist the self-repair process of the passivation film.

[0037] Through electrochemical impedance spectroscopy (EIS) testing, it is found that in the passivation film system containing this material, the low-frequency impedance value increases by two orders of magnitude, indicating that it significantly enhances the barrier effect and corrosion resistance of the film layer.

[0038] Cs x Electrochromic response mechanism of the Cs

[0039] Cs x WO3 is a typical near-infrared absorption type electrochromic material. When the x value is controlled between 0.3 - 0.5, it has good optical modulation ability and stability.

[0040] In the initial stage of corrosion, due to the change of local potential, Cs xW in WO3 6+ is reduced to W 5+ , resulting in a red shift of its absorption peak in the visible light region (Δλ = 120 nm), triggering an obvious color change from blue to dark gray (ΔE = 7.2), which can be recognized by the naked eye.

[0041] This color change phenomenon is highly linearly correlated with the corrosion potential (R 2 > 0.9), realizing a non-invasive and visual early warning function for early corrosion events, providing an intuitive basis for the maintenance of ship fittings.

[0042] Bionic enhancement component: PDA-NCC composite structure

[0043] To improve the adhesion and mechanical stability of the passivation film, the present invention introduces a bionic enhancement component based on polydopamine (PDA) and nanocrystalline cellulose (NCC), mimicking the biological adhesion and structure strengthening mechanisms in nature.

[0044] Strong interaction between the PDA coating and the metal surface:

[0045] PDA molecules contain abundant catechol and amino functional groups, which can be tightly bound to the Fe-OH groups on the stainless steel surface through pentadentate coordination. FTIR tests show that a characteristic peak appears at 1620 cm -1 , confirming the formation of coordination bonds.

[0046] The interfacial bonding force reaches grade 5B in ASTM D3359 standard, and the interfacial binding energy reaches 12.5 J / m 2 (scratch test), greatly improving the adhesion performance of the passivation film.

[0047] When local corrosion causes the medium pH to rise above 9, PDA can release NH4 + , neutralize acidic corrosion products, and slow down the corrosion process.

[0048] Structural strengthening effect of NCC:

[0049] Nanocrystalline cellulose (NCC) forms a three-dimensional network structure with sodium carboxymethyl cellulose (CMC-Na) through hydrogen bonds, and the storage modulus G’ is increased to 850 Pa, significantly enhancing the flexibility and crack propagation resistance of the passivation film.

[0050] Experimental results show that this structure can increase the crack propagation resistance by 3 times, effectively preventing the formation of microcracks in the film layer due to mechanical stress or thermal expansion and contraction.

[0051] Corrosion inhibitor carrier: phytic acid-ZrO2 nanoclusters

[0052] To achieve the long-term corrosion inhibition effect of the passivation film, the present invention designs an intelligent responsive corrosion inhibitor carrier - phytic acid (Phytic Acid) modified ZrO2 nanoclusters.

[0053] Supramolecular structure construction and slow release mechanism:

[0054] Phytic acid molecules contain 6 phosphate groups and can react with Zr 4+ to form a stable [Zr(Phy)] 2- supramolecular structure. Dynamic light scattering (DLS) tests show that this structure has a strong negative charge (Zeta potential = -42 mV), ensuring its uniform dispersion in the passivation solution.

[0055] Under Cl - erosion conditions, the [Zr(Phy)] 2- structure gradually dissociates, releasing Phy 6- anions. Phy 6- can react with Fe 2+ to form a dense chelate protection layer (SEM images show a thickness < 100 nm), effectively preventing further metal dissolution.

[0056] Role of nanoclusters in filling pores:

[0057] The particle size of ZrO2 nanoclusters is controlled at about 5 nm, which can effectively fill the internal micropores of the passivation film. The results of mercury intrusion porosimetry tests show that the porosity of the film layer decreases from the original 8% to 0.3%, significantly reducing the penetration path of corrosive media and improving the overall shielding performance.

[0058] To improve the interfacial bonding force and component dispersion stability between the passivation film and the stainless steel substrate, the present invention adopts a strategy of synergistic action of silane coupling agent and amphiphilic block copolymer PS-b-PAA.

[0059] Interface modification effect of silane coupling agent:

[0060] The selected silane coupling agent (such as γ-aminopropyltriethoxysilane or γ-glycidoxypropyltrimethoxysilane) can form Si-O-Fe covalent bonds with Fe-OH on the stainless steel surface. XPS analysis shows that the Fe 2p3 / 2 peak shifts by 0.8 eV, indicating an obvious interfacial chemical reaction.

[0061] This interfacial bonding mode makes the bonding energy between the passivation film and the substrate as high as 12.5 J / m 2 , greatly improving the overall adhesion and durability of the film layer.

[0062] Stabilizing effect of PS-b-PAA dispersant:

[0063] In the amphiphilic block copolymer PS-b-PAA, the PAA chain segment can be adsorbed on the surface of nanoparticles such as carbon nanotubes and graphene quantum dots through hydrogen bonding (the adsorption amount reaches 1.2 mg / m 2 ), effectively preventing their aggregation.

[0064] In this system, the absolute value of the Zeta potential of the nanomaterials is greater than 40 mV, ensuring their good dispersion stability in the passivation solution for more than 30 days, which is beneficial to the implementation of subsequent coating processes.

[0065] According to the embodiments of the present invention, MoS2 quantum dots are doped in the ZnO / ZnFe2O4 heterojunction, and the loading amount of the MoS2 quantum dots is 0.5-1.5% of the total mass of the ZnO / ZnFe2O4 heterojunction.

[0066] According to the embodiments of the present invention, the particle size of the phytic acid-modified ZrO2 nanoclusters is 3-8 nm;

[0067] The surface of the phytic acid-modified ZrO2 nanoclusters has a porous coordination network formed by phytic acid phosphate groups and Zr 4+ with a pore size of 0.5-2 nm.

[0068] According to the embodiments of the present invention, the shell layer of polyaniline in the PANI@Cs x WO3 core-shell microspheres is in the form of Emeraldine salt, and the x value of Cs x WO3 is 0.3-0.5.

[0069] According to the embodiments of the present invention, the surface of the Ti3C2Tx / MXene is modified with octadecyltrichlorosilane to make its water contact angle ≥ 110°.

[0070] According to the embodiments of the present invention, in the ZnO / ZnFe2O4 heterojunction, the molar ratio of ZnFe2O4 to ZnO is 1:(2-4);

[0071] Ti3C2Tx / MXene is coated on the surface of the ZnO / ZnFe2O4 heterojunction in the form of sheets, and the sheet thickness ≤ 10 nm.

[0072] According to the embodiments of the present invention, the passivation film has a film thickness of 5-20 μm and a neutral salt spray test tolerance time ≥ 3500 h.

[0073] According to the embodiments of the present invention, in the initial stage of corrosion, the passivation film shows a visible color change (ΔE>5) through the electrochromic effect of Cs x WO3, and the color change area is linearly correlated with the corrosion potential distribution (R2>0.9).

[0074] According to a second aspect of the present invention, there is provided a method for preparing a stainless steel passivation film for ship fittings, comprising the following steps:

[0075] Step S1: Prepare a multifunctional nanocomposite (MNC): Dissolve Zn(NO3)2·6H2O and Fe(NO3)3·9H2O in deionized water according to a Zn:Fe molar ratio of (2-4):1, add sodium citrate as a complexing agent, adjust the pH to 9-10, and perform a hydrothermal reaction (120-150 °C, 6-8 h) to generate a ZnO / ZnFe2O4 heterojunction;

[0076] Disperse the ZnO / ZnFe2O4 heterojunction and Ti3C2Tx / MXene in ethanol, perform ultrasonic treatment and then centrifugal drying to obtain the multifunctional nanocomposite;

[0077] Step S2: Prepare an electrochromic-anticorrosive bifunctional material: Mix Cs2CO3 and Na2WO4·2H2O according to a Cs:W molar ratio of (0.3-0.5):1, and heat to 180 °C for 12 h by hydrothermal method to synthesize Cs x WO3 nanoparticles;

[0078] Disperse Cs x WO3 in a hydrochloric acid solution containing aniline monomer, add ammonium persulfate to initiate polymerization, after reacting for 24 h, perform centrifugal washing to obtain PANI@Cs x WO3 core-shell microspheres;

[0079] Step S3: Prepare a bionic reinforcement component: Dissolve dopamine hydrochloride in Tris-HCl buffer (pH = 8.5), add an NCC suspension, stir magnetically for 24 h, perform centrifugation and then freeze-dry to obtain the bionic reinforcement component;

[0080] Step S4: Prepare a passivation film solution: Ultrasonically disperse deionized water, a silane coupling agent, and a dispersion stabilizer (40 kHz, 30 min) to obtain a dispersion base liquid;

[0081] Add the functional nanocomposite, the PANI@Cs x WO3 microspheres, the phytic acid-ZrO2 nanoclusters, and a conductive enhancer to the dispersion base liquid, and perform microwave-assisted stirring to obtain a uniform passivation film solution.

[0082] According to an embodiment of the present invention, the preparation method of Ti3C2Tx / MXene in step S1 includes:

[0083] Immerse the Ti3AlC2 MAX phase in an HCl solution containing LiF, with a LiF concentration of 6-9 mol / L, etch at 40 °C for 24 h, perform centrifugal washing until the pH > 6, and perform ultrasonic exfoliation (under argon protection, 1 h) and then vacuum drying.

[0084] According to an embodiment of the present invention, in step S4, the frequency of the microwave-assisted stirring is 2.45 GHz, the microwave power is 200 - 400 W, the temperature is 60 °C, and the time is 20 min.

[0085] According to an embodiment of the present invention, in step S1, the heating temperature of the hydrothermal reaction is 120 - 150 °C, and the time is 6 - 8 h;

[0086] The power of the ultrasonic treatment is 300 W, and the time is 2 h.

[0087] The present invention proposes a brand-new stainless steel passivation film for ship fittings and its preparation method. By introducing various innovative elements such as multifunctional nanocomposites and electrochromic-anticorrosion bifunctional materials, it aims to overcome the deficiencies of the existing technology and provide more comprehensive and effective protection for ship fittings.

[0088] Through the collaborative design of multi-scale functional materials, the present invention constructs a new type of stainless steel passivation film system for ship fittings that integrates high-efficiency anti-corrosion, self-cleaning, electrochromic visual warning, bionic enhancement, intelligent corrosion inhibition release, and high interfacial bonding strength. All performance indicators are superior to the existing technology, especially suitable for harsh marine environments such as high salinity, high humidity, and strong ultraviolet radiation, and have broad engineering application prospects and industrialization value. Detailed implementation manners

[0089] The embodiment of the present application provides a stainless steel passivation film for ship fittings.

[0090] Example 1

[0091] ZnO / ZnFe2O4@Ti3C2Tx / MXene / MoS2 quantum dots: 4 parts;

[0092] PANI@Cs x WO3 core-shell microspheres: 3 parts;

[0093] PDA-NCC composite: 1 part;

[0094] Phytic acid-ZrO2 nanoclusters: 2 parts;

[0095] Silane coupling agent: 2 parts;

[0096] Dispersion stabilizer: 0.5 part;

[0097] Conductive enhancer: 0.2 part;

[0098] Deionized water: the balance.

[0099] Example 2

[0100] ZnO / ZnFe2O4@Ti3C2Tx / MXene / MoS2 quantum dots: 5 parts;

[0101] PANI@Cs x WO3 core-shell microspheres: 4 parts;

[0102] PDA-NCC composite: 1.5 parts;

[0103] Phytic acid-ZrO2 nanoclusters: 2.5 parts;

[0104] Silane coupling agent: 3 parts;

[0105] Dispersion stabilizer: 1 part;

[0106] Conductive enhancer: 0.4 part;

[0107] Deionized water: the balance.

[0108] Example 3

[0109] ZnO / ZnFe2O4@Ti3C2Tx / MXene / MoS2 quantum dots: 6 parts;

[0110] PANI@Cs x WO3 core-shell microspheres: 5 parts;

[0111] PDA-NCC composite: 2 parts;

[0112] Phytic acid-ZrO2 nanoclusters: 3 parts;

[0113] Silane coupling agent: 4 parts;

[0114] Dispersion stabilizer: 1.5 parts;

[0115] Conductive enhancer: 0.6 part;

[0116] Deionized water: the balance.

[0117] Example 4 (doped with MoS2 quantum dots)

[0118] ZnOZnFe2O4@Ti3C2Tx MXene / MoS2 quantum dots (containing MoS2): 5 parts; PANI@Cs x WO3 core-shell microspheres: 4 parts;

[0119] PDA-NCC composite: 1.5 parts;

[0120] Phytic acid-ZrO2 nanoclusters: 2.5 parts;

[0121] Silane coupling agent: 3 parts;

[0122] Dispersion stabilizer: 1 part;

[0123] Conductive enhancer: 0.4 parts;

[0124] Deionized water: the balance.

[0125] Example 5 (without PANI@Cs x WO3)

[0126] ZnO / ZnFe2O4@Ti3C2Tx / MXene / MoS2 quantum dots: 5 parts;

[0127] PDA-NCC complex: 1.5 parts;

[0128] Phytic acid-ZrO2 nanoclusters: 2.5 parts;

[0129] Silane coupling agent: 3 parts;

[0130] Dispersion stabilizer: 1 part;

[0131] Conductive enhancer: 0.4 parts;

[0132] Deionized water: the balance.

[0133] Example 6 (without phytic acid-ZrO2 nanoclusters)

[0134] ZnO / ZnFe2O4@Ti3C2Tx / MXene / MoS2 quantum dots: 5 parts;

[0135] PANI@Cs x WO3 core-shell microspheres: 4 parts;

[0136] PDA-NCC complex: 1.5 parts;

[0137] Silane coupling agent: 3 parts;

[0138] Dispersion stabilizer: 1 part;

[0139] Conductive enhancer: 0.4 parts;

[0140] Deionized water: the balance.

[0141] Comparative Example 1 (conventional chromate passivation)

[0142] Chromate passivation solution (commercially available).

[0143] Comparative Example 2 (without MXene coating)

[0144] ZnO / ZnFe2O4 heterojunction: 5 parts;

[0145] PANI@Cs x WO3 core-shell microspheres: 4 parts;

[0146] PDA-NCC complex: 1.5 parts;

[0147] Phytic acid-ZrO2 nanoclusters: 2.5 parts;

[0148] Silane coupling agent: 3 parts;

[0149] Dispersion stabilizer: 1 part;

[0150] Conductive enhancer: 0.4 part;

[0151] Deionized water: the balance.

[0152] Comparative example 3 (without PDA-NCC complex)

[0153] ZnO / ZnFe2O4@Ti3C2Tx / MXene / MoS2 quantum dots: 5 parts;

[0154] PANI@Cs x WO3 core-shell microspheres: 4 parts;

[0155] Phytic acid-ZrO2 nanoclusters: 2.5 parts;

[0156] Silane coupling agent: 3 parts;

[0157] Dispersion stabilizer: 1 part;

[0158] Conductive enhancer: 0.4 part;

[0159] Deionized water: the balance.

[0160] Comparative example 4 (without conductive enhancer)

[0161] ZnO / ZnFe2O4@Ti3C2Tx / MXene / MoS2 quantum dots: 5 parts;

[0162] PANI@Cs x WO3 core-shell microspheres: 4 parts;

[0163] PDA-NCC complex: 1.5 parts;

[0164] Phytic acid-ZrO2 nanoclusters: 2.5 parts;

[0165] Silane coupling agent: 3 parts;

[0166] Dispersion stabilizer: 1 part;

[0167] Deionized water: the balance.

[0168] Experimental example:

[0169] 1. Corrosion resistance test

[0170] Neutral Salt Spray Test (NSS): Conducted in accordance with ASTM B117 standard, and record the time when obvious corrosion appears on the surface of the specimen.

[0171] Electrochemical Impedance Spectroscopy (EIS): Use a three-electrode system to measure the low-frequency impedance value in 3.5% NaCl solution.

[0172] 2. Self-cleaning ability test

[0173] Ultraviolet-Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS): Determine the separation efficiency of photogenerated electron-hole pairs.

[0174] Degradation rate test: Under simulated sunlight irradiation, measure the degradation rate of organic dyes (such as methyl orange).

[0175] 3. Mechanical property test

[0176] Hardness test: Use a Vickers hardness tester to measure the hardness of the film layer.

[0177] Wear resistance test: Use a Taber abrasion tester to record the number of revolutions required for the film layer to wear until the substrate is exposed.

[0178] 4. Electrochromic visualization warning test

[0179] Color change test: At the initial stage of corrosion, measure the color change ΔE value through a color difference meter.

[0180] Potential change monitoring: Use a potentiometer to record the correlation between local potential change and color change. The results are shown in Table 1.

[0181] Table 1. Performance test results of Examples 1-6 and Comparative Examples 1-4

[0182]

[0183] Examples 1-4 demonstrate excellent corrosion resistance, high photogenerated carrier separation efficiency, good self-cleaning ability, and significant color change warning function. In particular, the doping of MoS2 quantum dots further improves the corrosion resistance and photocatalytic activity.

[0184] In Examples 5 and 6, PANI@Cs x WO3 and phytic acid-ZrO2 nanoclusters were removed respectively, resulting in a decrease in corrosion resistance and color change warning function.

[0185] In Comparative Example 1, a traditional chromate passivation solution was used, and its various properties are inferior to those of the novel passivation film provided by the present invention.

[0186] In Comparative Examples 2-4, the MXene coating layer, the PDA-NCC composite, and the conductive enhancer were removed respectively, and the results showed that these components were crucial for improving the overall performance of the passivation film.

[0187] In summary, the stainless steel passivation film for ship fittings and its preparation method proposed by the present invention have significant technical advantages and are applicable to application scenarios with extremely high requirements for weather resistance and corrosion resistance in marine environments. Although the preferred embodiments of the present invention have been described, those skilled in the art can make additional changes and modifications to these embodiments once they know the basic creative concept. Therefore, the appended claims are intended to be construed as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0188] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention is also intended to include these modifications and variations.

Claims

1. A stainless steel passivation film for ship fittings, characterized in that, It is prepared from the following components in parts by weight: 4 - 6 parts of multifunctional nanocomposite material: including nanoparticles composed of ZnO / ZnFe₂O₄ heterojunction and Ti₃C₂Tx / MXene composite, 3-5 parts of electrochromic-anticorrosive bifunctional material: PANI@Cs x WO3 formed WO3 core-shell microspheres, where Cs x WO3 accounts for 15-30% of the total mass of the PANI@Cs x WO3 core-shell microspheres; x ​ 1 - 2 parts of bionic reinforcement component: including polydopamine coating and nanocellulose crystals, wherein the mass ratio of the polydopamine coating to the nanocellulose crystals is (1:1) - (2:1); 2 - 3 parts of corrosion inhibitor carrier: phytic acid - modified ZrO₂ nanoclusters, wherein the chelation molar ratio of phytic acid to ZrO₂ is (1:1) - (1:2); 2 - 4 parts of silane coupling agent: selected from γ - aminopropyltriethoxysilane or γ - (2,3 - epoxypropoxy)propyltrimethoxysilane; 0.5 - 1.5 parts of dispersion stabilizer: including sodium carboxymethylcellulose and amphiphilic block copolymer, and the mass ratio of the sodium carboxymethylcellulose to the amphiphilic block copolymer is (3:1) - (5:1); 0.2 - 0.6 parts of conductive enhancer: a mixture of carbon nanotubes and graphene quantum dots treated by ultrasonic - microwave synergistic exfoliation method, and the mass ratio of the carbon nanotubes to the graphene quantum dots is (1:2) - (2:1); The balance is deionized water.

2. The passivation film according to claim 1, wherein MoS₂ quantum dots are doped in the ZnO / ZnFe₂O₄ heterojunction, and the loading amount of MoS₂ quantum dots is 0.5 - 1.5% of the total mass of the ZnO / ZnFe₂O₄ heterojunction.

3. The passivation film according to claim 1, wherein, The particle size of the phytic acid - modified ZrO₂ nanoclusters is 3 - 8 nm; The surface of the phytic acid-modified ZrO2 nanoclusters has a porous coordination network formed by the phytic acid phosphate groups and Zr 4+ with a pore size of 0.5 - 2 nm.

4. The passivation film according to claim 1, wherein The shell - layer polyaniline of the PANI@CsxWO₃ core - shell microspheres is in the form of Emeraldine salt, and the x value of CsxWO₃ is 0.3 - 0.

5.

5. The passivation film according to claim 1, characterized in that, The surface of the Ti₃C₂Tx / MXene is modified by octadecyltrichlorosilane to make its water contact angle ≥ 110°.

6. The passivation film according to claim 1, wherein, In the ZnO / ZnFe₂O₄ heterojunction, the molar ratio of ZnFe₂O₄ to ZnO is 1:(2 - 4); Ti₃C₂Tx / MXene coats the surface of the ZnO / ZnFe₂O₄ heterojunction in the form of sheets, and the sheet thickness ≤ 10 nm.

7. A method for preparing a stainless steel passivation film for a ship fitting according to any one of claims 1-6, characterized in that, It includes the following steps: Step S1: Prepare the multifunctional nanocomposite material: Dissolve Zn(NO₃)₂·6H₂O and Fe(NO₃)₃·9H₂O in deionized water according to the Zn:Fe molar ratio of (2 - 4):1, add sodium citrate as a complexing agent, adjust the pH to 9 - 10, and perform a hydrothermal reaction to generate ZnO / ZnFe₂O₄ heterojunction; Disperse the ZnO / ZnFe₂O₄ heterojunction and Ti₃C₂Tx / MXene in ethanol, perform ultrasonic treatment and then centrifugal drying to obtain the multifunctional nanocomposite material; Step S2: Prepare the electrochromic - anticorrosion bifunctional material: Mix Cs₂CO₃ and Na₂WO₄·2H₂O according to the Cs:W molar ratio of (0.3 - 0.5):1, heat to 180 °C by hydrothermal method for 12 h to synthesize CsxWO₃ nanoparticles; Disperse CsxWO₃ in a hydrochloric acid solution containing aniline monomer, add ammonium persulfate to initiate polymerization, and after reacting for 24 h, perform centrifugal washing to obtain PANI@CsxWO₃ core - shell microspheres; Step S3: Preparation of the bionic enhancement component: Dissolve dopamine hydrochloride in Tris-HCl buffer solution, add the NCC suspension, stir magnetically for 24 h, centrifuge and then freeze-dry to obtain the bionic enhancement component; Step S4: Preparation of the passivation film solution: Add deionized water, silane coupling agent, and dispersion stabilizer, and perform ultrasonic dispersion to obtain a dispersion base liquid; Add the functional nanocomposite material, the PANI@CsxWO3 microspheres, the phytic acid-ZrO2 nanoclusters, and the conductive enhancer to the dispersion base liquid, and perform microwave-assisted stirring to obtain a uniform passivation film solution.

8. The preparation method according to claim 7, characterized in that, The preparation method of the Ti3C2Tx / MXene in Step S1 includes: Immerse the Ti3AlC2 MAX phase in an HCl solution containing LiF with a concentration of 6-9 mol / L, etch at 40 °C for 24 h, centrifuge and wash until the pH > 6, and perform ultrasonic exfoliation and then vacuum drying.

9. The preparation method according to claim 7, characterized in that, In Step S4, the frequency of the microwave-assisted stirring is 2.45 GHz, the microwave power is 200-400 W, the temperature is 60 °C, and the time is 20 min.

10. The preparation method according to claim 7, characterized in that, In Step S1, the heating temperature of the hydrothermal reaction is 120-150 °C, and the time is 6-8 h; The power of the ultrasonic treatment is 300 W, and the time is 2 h.

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