Zif-67@silane coupling agent modified hydroxyapatite nanowire self-repairing epoxy resin anticorrosive coating and preparation method thereof

Abstract

The application discloses a kind of ZIF-67@ silane coupling agent modified hydroxyapatite nanowire self-repairing epoxy resin anticorrosion coating and its preparation method, the preparation method includes: first, hydroxyapatite nanowire is prepared, is surface modified with 3-aminopropyl triethoxysilane, and APTES@HAP is obtained;APTES@HAP is used as substrate, and ZIF-67 is in situ grown on its surface, and ZIF-67@APTES@HAP composite powder is obtained;The composite powder is sprayed on the surface of metal substrate after being blended with epoxy resin, and the anticorrosion coating is obtained after curing;The coating has the high aspect ratio physical barrier function of HAP nanowire and the corrosion response self-repairing function of ZIF-67, can release cobalt ion to form protective film when coating is damaged, significantly improve the long-acting anticorrosion performance of metal.The preparation process of the application is simple, easy to mass production, and suitable for the anticorrosion protection of metal structure in the fields of ocean engineering, petrochemical industry and the like.

Description

Technical Field

[0001] This invention relates to the field of metal corrosion protection materials, and in particular to a ZIF-67@silane coupling agent modified hydroxyapatite nanowire self-healing epoxy resin anti-corrosion coating and its preparation method. Background Technology

[0002] Metal corrosion is a major challenge facing global industry, causing enormous economic losses and safety hazards every year. Organic coatings, especially epoxy resin coatings, are widely used as the first line of defense against metal corrosion due to their excellent adhesion, chemical stability, and barrier properties. However, traditional epoxy resin coatings are prone to developing microcracks during long-term service due to mechanical damage, aging, or localized defects. This allows corrosive media (such as water, oxygen, and chloride ions) to penetrate into the metal substrate, initiating localized corrosion and significantly shortening the coating's service life.

[0003] To address these issues, researchers have attempted to introduce nanofillers into epoxy resins to improve the physical shielding properties of the coating. Hydroxyapatite (HAP) nanowires, due to their high aspect ratio and mechanical strength, can serve as a reinforcing phase for coatings. For example, some literature reports the use of silane coupling agents to modify the surface of nano-hydroxyapatite to improve its dispersibility in organic resins. However, pure HAP nanowires have high surface polarity, making them prone to aggregation in organic resins, and they lack active anti-corrosion functions, making it difficult to meet the requirements for long-term self-healing corrosion protection.

[0004] In recent years, metal-organic framework (MOF) materials have attracted attention in the field of anti-corrosion coatings due to their high specific surface area, tunable pore structure, and active metal centers. ZIF-67 (cobalt-based zeolite imidazole ester framework), as a typical MOF material, can serve as a corrosion inhibitor carrier or corrosion-responding unit due to its porous structure. Previous studies have used ZIF-67 to prepare superhydrophobic composite coatings, exhibiting excellent hydrophobicity and corrosion resistance. Chinese patent CN118185441B discloses a self-healing anti-corrosion coating based on MOF composite fillers, in which MOF nanoparticles load corrosion inhibitors and release them to form a protective film upon coating damage. Other literature reports the in-situ self-assembly of Zn on GO surfaces. 2+ To prepare a self-healing composite powder with imidazole ligand (CN120648278A).

[0005] However, the existing technology still has the following shortcomings: (1) When MOF materials are used directly as fillers, their dispersion uniformity and interfacial compatibility in the coating are often poor, which affects the long-term service performance of the coating; (2) In the existing schemes, MOFs are mostly in the form of nanoparticles, lacking morphological control of MOF growth substrates, making it difficult to fully utilize the synergistic enhancement effect of nanofillers; (3) There is no technical solution to organically integrate the physical barrier function of hydroxyapatite nanowires with the corrosion response function of ZIF-67 through interfacial bonding of silane coupling agents, and construct a multi-level composite structure of rigid reinforcement core-response repair shell-interfacial bonding layer.

[0006] Therefore, developing a self-healing anti-corrosion coating using silane coupling agent-modified hydroxyapatite nanowires as the in-situ growth substrate for ZIF-67, and improving the anti-corrosion performance of the coating through the multiple synergistic effects of nano-reinforcement, interface optimization and active repair, has important practical significance and application value. Summary of the Invention

[0007] The purpose of this invention is to solve the technical problems existing in the prior art and to provide a ZIF-67@silane coupling agent modified hydroxyapatite nanowire self-healing epoxy resin anti-corrosion coating and its preparation method.

[0008] To achieve the above objectives, the technical solution provided by this invention is: a method for preparing a self-healing epoxy resin anti-corrosion coating of ZIF-67@silane coupling agent modified hydroxyapatite nanowires. The method first prepares hydroxyapatite nanowires, then modifies their surface with 3-aminopropyltriethoxysilane to obtain APTES@HAP; then, using APTES@HAP as a substrate, ZIF-67 is grown in situ on its surface to obtain ZIF-67@APTES@HAP composite powder; the composite powder is then mixed with epoxy resin and sprayed onto the surface of a metal substrate. After curing, the anti-corrosion coating is obtained. The specific steps are as follows: S1. Preparation of hydroxyapatite nanowires, i.e., HAP; S2. Disperse the hydroxyapatite nanowires prepared in step S1 in an organic solvent, add a silane coupling agent and stir to react, and then wash and dry to obtain silane coupling agent modified hydroxyapatite nanowires, namely APTES@HAP. S3. Immerse the APTES@HAP powder obtained in step S2 into a solution containing cobalt salt, then add a solution containing dimethylimidazole, stir, let it stand to precipitate, wash and dry to obtain ZIF-67@silane coupling agent modified hydroxyapatite nanowire composite powder, namely ZIF-67@APTES@HAP powder. S4. Disperse the ZIF-67@APTES@HAP powder obtained in step S3 in an organic solvent, add epoxy resin component A and epoxy resin component B in sequence, and stir to mix to obtain a composite slurry. S5. Spray the composite slurry obtained in step S4 onto the pretreated metal substrate surface, and after curing, obtain the ZIF-67@silane coupling agent modified hydroxyapatite nanowire self-healing epoxy resin anti-corrosion coating.

[0009] Preferably, in step S1, the hydroxyapatite nanowires are prepared by a hydrothermal method; the hydrothermal method is used to obtain a one-dimensional nanowire structure with a high aspect ratio and good crystallinity.

[0010] Preferably, in step S2, the organic solvent is ethanol and the silane coupling agent is 3-aminopropyltriethoxysilane, i.e., APTES.

[0011] Specifically, the amino groups in its molecule can chemically bond with epoxy resin, and the ethoxy groups can undergo hydrolytic condensation with the hydroxyl groups on the surface of HAP nanowires, thereby forming covalent bonds between the inorganic filler and the organic resin, significantly improving the dispersibility and interfacial compatibility of the filler in the resin matrix. Simultaneously, the grafted layer of APTES provides abundant active sites for the subsequent in-situ growth of ZIF-67.

[0012] Preferably, in step S2, the mass-to-volume ratio of hydroxyapatite nanowires to silane coupling agent is 0.4 g:(5~20) ml, and the stirring reaction is carried out at 60~100℃ for 4~12 h.

[0013] Preferably, in step S3, the cobalt salt is cobalt nitrate, and the molar ratio of dimethylimidazole to cobalt salt in the solution containing dimethylimidazole is 2:1 to 6:1; specifically, ZIF-67 can be grown in situ on the surface of APTES@HAP by stirring at room temperature to form a core-shell composite structure with HAP nanowires as the core and ZIF-67 as the shell.

[0014] Preferably, in step S3, the settling time is 12~48 h.

[0015] Preferably, in step S4, the mass ratio of ZIF-67@APTES@HAP powder to epoxy resin component A is 0.02~0.1:1, and the mass ratio of epoxy resin component A to epoxy resin component B is 1:0.1~0.3.

[0016] Preferably, in step S4, the organic solvent is ethyl acetate, and epoxy resin component A includes an active diluent, dibutyl phthalate, calcium carbonate, silica powder, KH-560 silane coupling agent, and defoamer; epoxy resin B includes polyamide 650 curing agent, modified fatty amine, DMP-30 accelerator, silica powder, talc, and coupling agent.

[0017] Preferably, in step S5, the spraying is done by air spraying, the spraying pressure is 2~10 kPa, and the spraying distance is 15~30cm; the metal substrate is carbon steel, and the pretreatment includes grinding, ultrasonic cleaning and drying.

[0018] The ZIF-67 (cobalt-based zeolite imidazole ester skeleton) described in this invention is composed of Co 2+ It coordinates with 2-methylimidazole to form a regular pore structure. When the coating develops microcracks due to mechanical damage or aging, the corrosive medium (Cl...)... - OH - Invasion of ZIF-67 into the damaged area leads to changes in the local microenvironment (such as an increase in pH), triggering partial dissociation of the ZIF-67 structure and releasing Co. 2+ Co 2+ With OH in corrosive media - The reaction forms a protective film of cobalt-based hydroxide or layered bimetallic hydroxide (LDH), which seals the damaged area and blocks further penetration of corrosive media, thereby achieving self-repair.

[0019] This invention also discloses a self-healing epoxy resin anti-corrosion coating of ZIF-67@silane coupling agent modified hydroxyapatite nanowires prepared according to the above-described preparation method. The anti-corrosion coating is a composite filler layer of ZIF-67@silane coupling agent modified hydroxyapatite nanowires uniformly dispersed in an epoxy resin matrix. The composite filler layer is a multi-level composite structure with hydroxyapatite nanowires as the core, silane coupling agent as the interfacial bonding layer, and ZIF-67 as the shell. This structure achieves organic bonding at the molecular level between the inorganic reinforcing phase (HAP nanowires) and the responsive repair phase (ZIF-67) through the chemical bridging effect of the silane coupling agent, and forms a strong interfacial bond with the epoxy resin matrix.

[0020] Beneficial effects of this invention: Synergistic Structural Design and Performance Enhancement: This invention successfully constructed a multi-level composite structure of rigid reinforced core-responsive repair shell-interfacial bonding layer through silane coupling agent surface grafting and ZIF-67 in-situ growth. This structure utilizes the ZIF-67 channels to controllably release corrosion-inhibiting ions (Co) in a corrosive microenvironment. 2+ Meanwhile, relying on the high aspect ratio of hydroxyapatite nanowires to form a dense physical barrier network in the coating, the coating's high repair efficiency and long-term anti-corrosion capability are synergistically enhanced, overcoming the shortcomings of single-component fillers with limited performance.

[0021] Intelligent response and multiple protection mechanisms are integrated: In this invention, the ZIF-67 shell is highly responsive to local pH changes, which can trigger targeted release of Co when corrosion occurs. 2+The coating achieves self-repair of damaged areas; the silane coupling agent interface layer provides a hydrophobic barrier and chemical bonding, enhancing the interfacial bonding strength between the coating and the filler; hydroxyapatite nanowires enhance the mechanical strength and impermeability of the coating. These three elements form a triple synergistic protection system of active repair, physical barrier, and structural reinforcement, maintaining the integrity of the coating even in harsh corrosive environments.

[0022] The preparation process is controllable and highly adaptable: the preparation method is based on conventional processes such as hydrothermal synthesis, surface functionalization, in-situ growth, and blending curing. The process is clear, parameters are easy to control, and repeatability is good, requiring no complex equipment or harsh conditions. The resulting composite filler is compatible with various resin systems (epoxy resin, polyurethane, acrylic resin, etc.) and has the potential for large-scale production and engineering applications.

[0023] Significantly improved corrosion resistance: Electrochemical impedance spectroscopy (EIS) tests show that the composite coating prepared in this invention has significantly better impedance arc radius, impedance modulus, and phase angle than pure epoxy coating, HAP / EP coating, and ZIF-67 / EP coating, exhibiting the best resistance to corrosive media penetration and coating integrity. Scratch repair experiments show that the impedance arc of the coating increases in the reverse direction after damage, confirming its reliable self-healing ability.

[0024] In summary, the preparation process of this invention is simple and easy to scale up, and it is suitable for corrosion protection of metal structures in fields such as marine engineering and petrochemicals. Attached Figure Description

[0025] The accompanying drawings, which are provided to further illustrate the invention and constitute a part of this invention, are illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention.

[0026] Figure 1 This is a scanning electron microscope (SEM) image of the ZIF-67@APTES@HAP composite powder prepared in Example 1 of the present invention, showing that ZIF-67 crystals are uniformly grown on the surface of HAP nanowires, forming a core-shell structure.

[0027] Figure 2 This is a SEM image of the surface of the ZIF-67@APTES@HAP / EP composite coating prepared in Example 1 of the present invention, showing the dispersion state and interfacial bonding of the composite filler in the epoxy resin matrix.

[0028] Figure 3 The Nyquist spectra (electrochemical impedance spectroscopy) of different coating samples prepared in Example 1 and Comparative Examples 1-3 of the present invention in 3.5% NaCl solution are shown to compare the corrosion resistance of ZIF-67@APTES@HAP / EP composite coating, HAP / EP coating, ZIF-67 / EP coating and pure EP coating.

[0029] Figure 4 The Nyquist plots of the ZIF-67@APTES@HAP / EP composite coating prepared in Example 1 after scratch treatment, after immersion in 3.5% NaCl solution for different times, are used to characterize the self-healing behavior of the coating. Detailed Implementation

[0030] This section will describe in detail specific embodiments of the present invention. Preferred embodiments of the present invention are shown in the accompanying drawings. The purpose of the drawings is to supplement the textual description with graphics, so that people can intuitively and vividly understand each technical feature and overall technical solution of the present invention, but they should not be construed as limiting the scope of protection of the present invention.

[0031] Example 1: Preparation of ZIF-67@APTES@HAP / EP composite coating S1. Hydroxyapatite nanowires (HAP) were prepared by a hydrothermal method. Specifically, 0.1 mol Ca(NO3)2·4H2O and 0.06 mol NaH2PO4·2H2O were dissolved in 150 mL of deionized water, the pH was adjusted to 11 with ammonia, and the mixture was transferred to a hydrothermal reactor and reacted at 180℃ for 24 h. After cooling, the mixture was centrifuged, washed, and dried to obtain white HAP powder.

[0032] S2. Disperse 0.4 g HAP powder in 400 mL ethanol and sonicate for 1 h to form a uniform dispersion. Add 10 mL APTES, seal the mouth of the beaker with plastic wrap, and stir in an oil bath at 200 r / min at 80 °C for 8 h. After the reaction is complete, filter the mixture, disperse the precipitate with ethanol by sonication, filter again, repeat the washing 3 times, and dry in a vacuum drying oven at 60 °C for 12 h to obtain APTES@HAP powder.

[0033] S3. Prepare 160 mL of a mixed solution with an ethanol / methanol volume ratio of 1:1, denoted as solution a. Weigh 18.19 g / L of Co(NO3)2·6H2O and dissolve it in solution a, denoted as solution b; weigh 20.3 g / L of 2-methylimidazole and dissolve it in solution a, denoted as solution c. Immerse 0.4 g of the APTES@HAP powder obtained in step S2 into 80 mL of solution b and stir at 600 r / min for 30 min; then slowly add 80 mL of solution c and continue stirring at 600 r / min for 10 min. After standing for precipitation for 24 h, centrifuge at 8000 r / min for 3 min, wash three times with ethanol, and vacuum dry at 60℃ for 12 h to obtain ZIF-67@APTES@HAP composite powder.

[0034] S4. Take 0.05 g of the composite powder obtained in step S3 and disperse it in 10 g of ethyl acetate. Stir at 400 r / min for 10 min. Add 1 g of epoxy resin component A and continue stirring at 400 r / min for 10 min. Finally, add 0.2 g of epoxy resin component B and stir at 400 r / min for 2 min to obtain the composite slurry.

[0035] S5. Select a Q235 carbon steel sample and polish it sequentially with 300-grit, 600-grit, and 1200-grit sandpaper. Clean it ultrasonically with ethanol and dry it at 60℃ for 10 minutes. Before spraying, adjust the spray gun with a small amount of ethyl acetate until a uniform water mist is sprayed. Pour the composite slurry obtained in step S4 into the spray gun, adjust the air pressure to 4 kPa, keep the nozzle about 25 cm away from the metal substrate, and spray it evenly on the carbon steel surface. Dry it at room temperature for 6 hours to obtain the ZIF-67@APTES@HAP / EP anti-corrosion coating.

[0036] Comparative Example 1: Preparation of ZIF-67 / EP Coating Referring to the content of Example 1, steps S1 and S2 are the same. In step S3 (without adding APTES@HAP), equal amounts of cobalt nitrate and dimethylimidazole are directly reacted in an ethanol / methanol mixed solution (without adding a substrate) to obtain pure ZIF-67 powder. Then, following steps S4 and S5 of Example 1, 0.05 g of ZIF-67 powder is blended with epoxy resin, sprayed, and cured to obtain a ZIF-67 / EP coating.

[0037] Comparative Example 2: Preparation of APTES@HAP / EP Coating Following step S2 of Example 1, APTES@HAP powder was prepared. Then, following steps S4 and S5 of Example 1, 0.05 g of APTES@HAP powder was blended with epoxy resin, sprayed, and cured to obtain an APTES@HAP / EP coating.

[0038] Comparative Example 3: Preparation of Pure EP Coating Following steps S4 and S5 of Example 1, but without adding any powder filler, epoxy resin components A and B are mixed in ethyl acetate at a mass ratio of 1:0.2, sprayed and cured to obtain a pure EP coating.

[0039] Comparative Example 4: Blank carbon steel substrate The Q235 carbon steel test piece was polished, cleaned, and dried according to step S5 of Example 1, without applying any coating.

[0040] Performance Testing and Results Analysis (1) Microscopic morphological characterization The morphology of the ZIF-67@APTES@HAP composite powder and composite coating prepared in Example 1 was observed using a scanning electron microscope.

[0041] Figure 1 SEM image of ZIF-67@APTES@HAP composite powder. From Figure 1 As can be seen, the HAP nanowires possess a smooth surface and a one-dimensional linear morphology, with a length of approximately 10-30 μm and a diameter of approximately 50-150 nm. ZIF-67 crystals (approximately 200-500 nm in size) grow uniformly and densely on the surface of the HAP nanowires, forming a complete "core-shell" structure, and no free ZIF-67 particles were observed. This indicates that the APTES-modified layer provides sufficient active sites for the in-situ growth of ZIF-67, and the growth process is controllable.

[0042] Figure 2 SEM image of the ZIF-67@APTES@HAP / EP composite coating surface. (From...) Figure 2 As can be seen, the composite filler is uniformly dispersed in the epoxy resin matrix without obvious agglomeration, and the interface between the filler and the resin is tightly bonded. This indicates that the grafting of APTES effectively improves the interfacial compatibility between the filler and the resin, which is beneficial for fully utilizing the reinforcing and functionalizing effects of the filler.

[0043] (2) Electrochemical impedance spectroscopy (EIS) test The ZIF-67@APTES@HAP / EP composite coating (denoted as ZIF-67@APTES@HAP / EP) prepared in Example 1, the ZIF-67 / EP coating (denoted as ZIF-67 / EP) prepared in Comparative Example 1, the APTES@HAP / EP coating (denoted as HAP / EP) prepared in Comparative Example 2, and the pure EP coating (denoted as EP) prepared in Comparative Example 3 were respectively immersed in 3.5 wt.% NaCl solution. EIS tests were performed at open circuit potential using an electrochemical workstation with a frequency range of 10 Hz. 5 Hz ~ 10 -2 The AC disturbance amplitude was 10 mV at Hz. The same test was performed on the blank carbon steel substrate as a control (Comparative Example 4).

[0044] Figure 3 Nyquist plots of each coating sample during the initial immersion stage. From... Figure 3 It can be seen that the ZIF-67@APTES@HAP / EP composite coating has the largest impedance arc radius, much larger than that of the HAP / EP coating, ZIF-67 / EP coating, and pure EP coating, indicating that the composite coating has the highest interfacial charge transfer impedance and the strongest resistance to corrosive media penetration. The impedance modulus diagram (not shown in the figure) shows that the low-frequency impedance modulus of the ZIF-67@APTES@HAP / EP composite coating (|Z|0.01 (Hz) reached 10 8 Ω·cm 2 The above values ​​are approximately two orders of magnitude higher than those of a pure EP coating, indicating a significant improvement in its physical shielding effect. In the phase angle diagram, the phase angle of this composite coating is high over a wide frequency range (10... 2 ~10 -1 The temperature is close to -90° within Hz, reflecting the integrity of the coating and the scarcity of defects. These results demonstrate that the multi-level composite structure of "HAP nanowire rigid reinforcement core + ZIF-67 responsive repair shell" constructed in this invention significantly improves the corrosion resistance of the coating through synergistic effects.

[0045] (3) Self-healing performance test Using a blade, cross-shaped scratches (approximately 100 μm wide) were made on the surface of the ZIF-67@APTES@HAP / EP composite coating prepared in Example 1, reaching the depth of the metal substrate. The sample was then immersed in a 3.5 wt.% NaCl solution, and EIS tests were performed on days 1, 2, 3, and 4 to observe the impedance changes at the scratches.

[0046] Figure 4 Nyquist plots of the scratch-resistant coating at different immersion times. From Figure 4 It is evident that after immersion for one day, the radius of the impedance arc at the scratch decreased compared to the initial state, which is due to the penetration of the corrosive medium along the scratch; however, after immersion for two days, the radius of the impedance arc began to increase; after immersion for three and four days, the radius of the impedance arc continued to increase, showing a clear reverse growth trend. This indicates that self-repair occurred at the scratch of the coating, and the protective performance of the coating gradually recovered.

[0047] (4) Overall performance comparison Based on the above test results, the ZIF-67@APTES@HAP / EP composite coating prepared in this invention achieves excellent physical shielding performance, interfacial compatibility, and corrosion-responsive self-healing performance through a multi-level synergistic mechanism of "rigid reinforcing core (HAP nanowires) - responsive repair shell (ZIF-67) - interfacial bonding layer (APTES)". Compared with single-component modified coatings (HAP / EP, ZIF-67 / EP) and pure EP coatings, the composite coating of this invention exhibits the best performance in electrochemical parameters such as impedance arc radius, low-frequency impedance modulus, and phase angle, and demonstrates significant self-healing ability after scratching. This indicates that the technical solution of this invention effectively solves the technical problem of achieving both long-term corrosion protection and self-healing function in existing technologies.

[0048] Without causing conflict, those skilled in the art can freely combine and use the above-mentioned additional technical features.

[0049] The above description is only a preferred embodiment of the present invention. Any technical solution that achieves the purpose of the present invention by essentially the same means is within the protection scope of the present invention.

Claims

1. A method for preparing a ZIF-67@silane coupling agent modified hydroxyapatite nanowire self-healing epoxy resin anti-corrosion coating, characterized in that: The preparation method first prepares hydroxyapatite nanowires, then modifies their surface with 3-aminopropyltriethoxysilane to obtain APTES@HAP; then, using APTES@HAP as a substrate, ZIF-67 is grown in situ on its surface to obtain ZIF-67@APTES@HAP composite powder; the composite powder is then blended with epoxy resin and sprayed onto the surface of a metal substrate, and after curing, an anti-corrosion coating is obtained. The specific steps are as follows: S1. Preparation of hydroxyapatite nanowires, i.e., HAP; S2. Disperse the hydroxyapatite nanowires prepared in step S1 in an organic solvent, add a silane coupling agent and stir to react, and then wash and dry to obtain silane coupling agent modified hydroxyapatite nanowires, namely APTES@HAP. S3. Immerse the APTES@HAP powder obtained in step S2 into a solution containing cobalt salt, then add a solution containing dimethylimidazole, stir, let it stand to precipitate, wash and dry to obtain ZIF-67@silane coupling agent modified hydroxyapatite nanowire composite powder, namely ZIF-67@APTES@HAP powder. S4. Disperse the ZIF-67@APTES@HAP powder obtained in step S3 in an organic solvent, add E44 epoxy resin component A and E44 epoxy resin component B in sequence, and stir to mix to obtain a composite slurry. S5. Spray the composite slurry obtained in step S4 onto the pretreated metal substrate surface, and after curing, obtain the ZIF-67@silane coupling agent modified hydroxyapatite nanowire self-healing epoxy resin anti-corrosion coating.

2. The preparation method according to claim 1, characterized in that: In step S1, hydroxyapatite nanowires are prepared by a hydrothermal method.

3. The preparation method according to claim 1, characterized in that: In step S2, the organic solvent is ethanol, and the silane coupling agent is 3-aminopropyltriethoxysilane, i.e., APTES.

4. The preparation method according to claim 1, characterized in that: In step S2, the mass-to-volume ratio of hydroxyapatite nanowires to silane coupling agent is 0.4 g:(5~20) ml, and the stirring reaction is carried out at 60~100℃ for 4~12 h.

5. The preparation method according to claim 1, characterized in that: In step S3, the cobalt salt is cobalt nitrate, and the molar ratio of dimethylimidazole to cobalt salt in the solution containing dimethylimidazole is 2:1 to 6:

1.

6. The preparation method according to claim 1, characterized in that: In step S3, the settling time is 12~48h.

7. The preparation method according to claim 1, characterized in that: In step S4, the mass ratio of ZIF-67@APTES@HAP powder to epoxy resin component A is 0.02~0.1:1, and the mass ratio of epoxy resin component A to epoxy resin component B is 1:0.1~0.

3.

8. The preparation method according to claim 7, characterized in that: In step S4, the organic solvent is ethyl acetate, and epoxy resin component A includes reactive diluent, dibutyl phthalate, calcium carbonate, silica powder, KH-560 silane coupling agent, and defoamer; epoxy resin B includes polyamide 650 curing agent, modified fatty amine, DMP-30 accelerator, silica powder, talc, and coupling agent.

9. The preparation method according to claim 1, characterized in that: In step S5, air spraying is used, with a spraying pressure of 2~10 kPa and a spraying distance of 15~30 cm; the metal substrate is carbon steel, and the pretreatment includes grinding, ultrasonic cleaning and drying.

10. A ZIF-67@silane coupling agent modified hydroxyapatite nanowire self-healing epoxy resin anti-corrosion coating prepared by the preparation method according to any one of claims 1-9, characterized in that: The anti-corrosion coating is a composite filler layer of ZIF-67@silane coupling agent modified hydroxyapatite nanowires uniformly dispersed in an epoxy resin matrix. The composite filler layer is a multi-level composite structure with hydroxyapatite nanowires as the core, silane coupling agent as the interface bonding layer, and ZIF-67 as the shell.

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