A composite nanomaterial, a preparation method and application thereof, a hydrogen-resistant anticorrosive coating material and application, and a hydrogen-resistant anticorrosive coating

Abstract

This invention relates to the field of hydrogen-barrier and anti-corrosion coating technology, and particularly to a composite nanomaterial, its preparation method and application, a hydrogen-barrier and anti-corrosion coating and its application, and a hydrogen-barrier and anti-corrosion coating. This invention provides a composite nanomaterial comprising dopamine-modified layered graphene and aluminum oxide; the dopamine-modified layered graphene and aluminum oxide are grafted together via a silane coupling agent; the composite nanomaterial is in the form of nanosheets. As an additive, the composite nanomaterial can enable the hydrogen-barrier and anti-corrosion coating to possess excellent hydrogen-barrier and anti-corrosion properties.

Description

Technical Field

[0001] This invention relates to the field of hydrogen-barrier and anti-corrosion coating technology, and in particular to a composite nanomaterial and its preparation method and application, hydrogen-barrier and anti-corrosion coating and its application, and hydrogen-barrier and anti-corrosion coating. Background Technology

[0002] In recent years, hydrogen, as a clean and efficient renewable energy carrier, has shown significant development potential in the green transformation of the energy system. However, the high permeability of hydrogen in metallic materials and the problem of hydrogen embrittlement seriously threaten the structural safety of gas pipelines during high-pressure transportation and long-term service. Therefore, developing composite internal coatings with excellent hydrogen barrier properties and corrosion resistance is an effective means to improve the service performance of metallic materials in hydrogen-resistant environments. Epoxy resins are widely used in the protection of metallic materials due to their dense film formation and strong adhesion, but their internal microstructure contains pores and their own hydrogen permeation resistance is limited, making it difficult to meet the service requirements under hydrogen transportation conditions. Summary of the Invention

[0003] In view of this, the purpose of this invention is to provide a composite nanomaterial, its preparation method and application, a hydrogen-blocking and anti-corrosion coating and its application, and a hydrogen-blocking and anti-corrosion coating layer. The composite nanomaterial, as an additive, can enable the hydrogen-blocking and anti-corrosion coating layer to possess excellent hydrogen-blocking and anti-corrosion properties.

[0004] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a composite nanomaterial comprising dopamine-modified layered graphene and aluminum oxide; The dopamine-modified layered graphene and aluminum oxide are grafted together via a silane coupling agent; The composite nanomaterial is a nanosheet.

[0005] Preferably, the silane coupling agent comprises one or more of 3-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane. The mass ratio of layered graphene to dopamine in the dopamine-modified layered graphene is (1~1.5):1.

[0006] Preferably, the mass ratio of the dopamine-modified layered graphene to the silane coupling agent is 1:(25~30). The total mass ratio of the dopamine-modified layered graphene and the silane coupling agent to the aluminum oxide is 1:(1~1.5).

[0007] This invention also provides a method for preparing the composite nanomaterials described above, comprising the following steps: Under alkaline conditions, a layered graphene dispersion was mixed with dopamine and then subjected to an in-situ growth reaction to obtain dopamine-modified layered graphene. The dopamine-modified layered graphene was mixed with anhydrous ethanol to obtain a dopamine-modified layered graphene dispersion. The dopamine-modified layered graphene dispersion was mixed with a silane coupling agent and subjected to a hydrolysis-silane coupling reaction to obtain dopamine-modified layered graphene grafted with a silane coupling agent. The composite nanomaterial is obtained by grafting dopamine-modified layered graphene, alumina, and a dispersion medium together with the grafted silane coupling agent.

[0008] Preferably, the pH value corresponding to the alkaline conditions is 8~10, the temperature of the in-situ growth reaction is 25~35℃, and the time is 20~24h; The hydrolysis-silane coupling reaction is carried out at a temperature of 65~75℃ for a time of 1.5~2.5h. The grafting temperature is 50~70℃, and the grafting time is 1.5~2.5h.

[0009] The present invention also provides the application of the composite nanomaterials described in the above technical solutions or the composite nanomaterials prepared by the preparation methods described in the above technical solutions in the preparation of hydrogen-barrier and anti-corrosion coatings.

[0010] The present invention also provides a hydrogen-barrier anti-corrosion coating, comprising epoxy resin, composite nanomaterials, curing agent and organic solvent; The composite nanomaterial is the composite nanomaterial described in the above technical solution or the composite nanomaterial prepared by the preparation method described in the above technical solution.

[0011] Preferably, the mass percentage of the composite nanomaterial to the total mass of the epoxy resin, composite nanomaterial and curing agent is 15-35%.

[0012] The present invention also provides the application of the hydrogen-barrier anti-corrosion coating described above in the preparation of hydrogen-barrier anti-corrosion coatings.

[0013] The present invention also provides a hydrogen-barrier and corrosion-resistant coating, comprising an epoxy resin and a composite nanomaterial embedded in the epoxy resin; The composite nanomaterial is the composite nanomaterial described in the above technical solution or the composite nanomaterial prepared by the preparation method described in the above technical solution.

[0014] This invention provides a composite nanomaterial comprising dopamine-modified layered graphene and aluminum oxide; the dopamine-modified layered graphene and aluminum oxide are grafted together via a silane coupling agent; the composite nanomaterial is a nanosheet. As an impermeable two-dimensional material, the composite nanomaterial's high aspect ratio structure forms continuous and overlapping multilayered physical barriers within the coating, significantly extending the diffusion path of hydrogen atoms and creating a typical "maze effect," thus reducing the effective permeation rate of hydrogen atoms. Furthermore, the layered arrangement of the nanosheets and their continuity in the hydrogen-blocking and anti-corrosion coating contribute to improving the coating's density and integrity; the dopamine in the dopamine-modified layered graphene forms a functional layer rich in hydroxyl and amino groups on the surface of the layered graphene, enabling the layered graphene nanosheets to form hydrogen bonds and π-π bonds with the epoxy resin matrix. The interaction between the organic and inorganic components enhances the bonding force at the organic-inorganic interface. This interfacial interaction not only improves the dispersibility and orientation regularity of layered graphene and inhibits agglomeration, but also effectively reduces the free volume in the polymer matrix, lowers the free channels for hydrogen diffusion, and the introduction of dopamine promotes the dense cross-linking of the epoxy network structure, improving the overall structural stability. Simultaneously, with the assistance of a silane coupling agent, the composite nanomaterial successfully grafts organic matter (dopamine) and inorganic matter (alumina) onto graphite nanosheets. This is achieved by relying on the Si-OH groups on the silane coupling agent to form covalent or hydrogen bonds with alumina and dopamine. This improves the interfacial activity of the composite particles, thereby promoting their dispersion and interfacial adhesion in the substrate of the hydrogen barrier and anti-corrosion coating, and enhancing the overall uniformity and structural integrity of the coating. Finally, the aluminum oxide in the composite nanomaterial, on the one hand, acts as an impermeable inorganic filler, which can further fill the micropores between epoxy resin or layered graphene sheets, making the hydrogen permeation path more complex and blocking the continuous permeation channels of hydrogen atoms; on the other hand, the abundant hydroxyl groups on the surface of aluminum oxide may undergo surface physical adsorption reactions with hydrogen atoms, thereby capturing hydrogen atoms and hindering hydrogen atom permeation.

[0015] This invention also provides a hydrogen-blocking and corrosion-resistant coating, comprising an epoxy resin and a composite nanomaterial embedded in the epoxy resin; the composite nanomaterial is the composite nanomaterial described in the above-mentioned technical solution or the composite nanomaterial prepared by the preparation method described in the above-mentioned technical solution. The hydrogen-blocking and corrosion-resistant coating possesses hydrogen-blocking properties, which can effectively prevent hydrogen atoms from penetrating into the metal substrate; the epoxy resin in the hydrogen-blocking and corrosion-resistant coating is itself a corrosion-resistant coating, and the composite nanomaterial embedded in the coating also has good chemical inertness, thereby giving the coating excellent corrosion resistance. Attached Figure Description

[0016] Figure 1The diagram shows the synthesis pathway of the composite nanomaterial described in this invention, where (a) is the oxidative self-polymerization reaction of DA, (b) is the modification reaction of PDA, (c) is the hydrolysis reaction of APTES, (d) is the modification reaction of APTES, and (e) is the modification reaction of alumina. Figure 2 This is a schematic diagram of the hydrogen permeation and hydrogen barrier mechanism of the hydrogen barrier and anti-corrosion coating described in this invention. Among them, (a) is a schematic diagram of the permeation process of hydrogen molecules in pure X80 steel, (b) is a schematic diagram of the permeation process of hydrogen molecules in X80 steel + EP coating, (c) is a schematic diagram of the permeation process of hydrogen molecules in X80 steel + hydrogen barrier and anti-corrosion coating described in Examples 1 to 6, (d) is the barrier effect of Gr on hydrogen and the positioning of hydrogen atoms on the Gr surface through CH sp3 bonds, (e) is the crystal structure of corundum phase (α-Al2O3), (f) is the single hydrogen atom (H) adsorption model, (g) is the hydrogen molecule (H2) adsorption model, and (h) is the diffusion path of H atoms in corundum phase (α-Al2O3). Figure 3 The changes in absorbance at different reaction temperatures during in-situ growth; Figure 4 The changes in absorbance under different pH conditions during in-situ growth; Figure 5 The changes in absorbance under different stirring rates during in-situ growth are shown. Figure 6 The changes in Raman spectra after hydrolysis-silane coupling agent were completed under different APTES addition amounts; Figure 7 The images shown are cross-sectional SEM images of the hydrogen-blocking and anti-corrosion coatings described in Examples 1 to 6, where (a) to (b) are pure epoxy resin coatings, (c) to (d) are the hydrogen-blocking and anti-corrosion coatings described in Example 1, (e) to (f) are the hydrogen-blocking and anti-corrosion coatings described in Example 2, (g) to (h) are the hydrogen-blocking and anti-corrosion coatings described in Example 3, (i) to (g) are the hydrogen-blocking and anti-corrosion coatings described in Example 4, (k) to (l) are the hydrogen-blocking and anti-corrosion coatings described in Example 5, and (m) to (n) are the hydrogen-blocking and anti-corrosion coatings described in Example 6. Figure 8 This is an elemental distribution diagram of the hydrogen-barrier and anti-corrosion coating described in Example 4; Figure 9 The image shows the EDS diagram and elemental percentage distribution of the surface of the hydrogen-blocking and anti-corrosion coating described in Example 4.

[0017] Figure 10 The electrochemical hydrogen permeation test bench (a) and the electrochemical hydrogen permeation curves (b) of X80 steel, pure epoxy resin coating and hydrogen-blocking anti-corrosion coating described in Examples 1-6 are shown in the test examples of this application. Figure 11The images show the Nyquist plot (a), Bode plot (b), Nyquist plot (c), Bode plot (d), and Bode plot (e) of X80 steel coated with pure epoxy (EP) coating at different immersion times. Detailed Implementation

[0018] This invention provides a composite nanomaterial comprising dopamine-modified layered graphene (denoted as Gr@PDA) and aluminum oxide; The dopamine-modified layered graphene and aluminum oxide are grafted together via a silane coupling agent; The composite nanomaterial is a nanosheet.

[0019] In this invention, the mass ratio of layered graphene to dopamine in the dopamine-modified layered graphene is preferably (1~1.5):1, more preferably 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1.

[0020] In this invention, the preparation method of the dopamine-modified layered graphene (Gr@PDA) preferably includes the following steps: Under alkaline conditions, a layered graphene dispersion was mixed with dopamine and then subjected to an in-situ growth reaction to obtain dopamine-modified layered graphene.

[0021] In this invention, the concentration of layered graphene in the layered graphene dispersion is preferably 0.8~1.2 g / L, more preferably 0.8 g / L, 0.9 g / L, 1 g / L, 1.1 g / L or 1.2 g / L. In an embodiment of this invention, the concentration of layered graphene in the layered graphene dispersion can be 1 g / L.

[0022] In this invention, the layered graphene dispersion is preferably obtained by dispersing layered graphene in water. In this invention, the layered graphene (Gr) preferably has 1 to 5 layers, and the carbon content is preferably >98%. In an embodiment of this invention, the layered graphene was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd. In this invention, the water is preferably deionized water. In this invention, the layered graphene with the above parameters exhibits good dispersion characteristics and can effectively suppress the aggregation and stacking of layered graphene.

[0023] This invention does not impose any special limitations on the dispersion process; any process well-known to those skilled in the art can be used, ensuring that the layered graphene is uniformly dispersed in water. In an embodiment of this invention, the dispersion is specifically performed under ultrasonic conditions, with a frequency of 55 Hz and a duration of 30 minutes.

[0024] In this invention, the mixing is preferably carried out by adding dopamine (DA) to the layered graphene dispersion under stirring conditions to adjust the pH value to alkaline.

[0025] In this invention, the stirring speed is preferably 1200~1800 rpm, more preferably 1200 rpm, 1300 rpm, 1400 rpm, 1500 rpm, 1600 rpm, 1700 rpm, or 1800 rpm. In an embodiment of this invention, the stirring speed can be 1600 rpm.

[0026] In this invention, the preferred mass ratio of layered graphene to dopamine in the layered graphene dispersion is (1~1.5):1, more preferably 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1 or 1.5:1. In an embodiment of this invention, the mass ratio of layered graphene to dopamine in the layered graphene dispersion can be 1:1.

[0027] The present invention does not impose any special limitations on the process of adding the dopamine; any process known to those skilled in the art can be used.

[0028] In this invention, the pH value corresponding to the alkalinity is preferably 8-10, more preferably 8, 8.5, 9, 9.5, or 10. In an embodiment of this invention, the pH value corresponding to the alkalinity is specifically 8.5. The pH adjuster used to adjust the pH value is preferably an alkaline solution, which is preferably one or more of sodium hydroxide solution, potassium hydroxide solution, ammonia water, sodium carbonate solution, and sodium bicarbonate solution. When the alkaline solution is two or more of the above-mentioned specific selections, this invention does not have any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. This invention does not have any special limitation on the concentration of the alkaline solution, and a process well known to those skilled in the art can be used.

[0029] In this invention, the temperature of the in-situ growth reaction is preferably 25~35℃, more preferably 25℃, 26℃, 27℃, 28℃, 29℃, 30℃, 31℃, 32℃, 33℃, 34℃ or 35℃; the time is preferably 20~24h, more preferably 20h, 21h, 22h, 23h or 24h. In an embodiment of this invention, the temperature of the in-situ growth reaction can be 30℃ and the time can be 24h.

[0030] In this invention, during the in-situ growth reaction, dopamine undergoes a self-polymerization reaction to generate polydopamine (PDA), which is then chemically adsorbed onto the surface of layered graphene and grown in situ under alkaline conditions. The aromatic ring structure in dopamine undergoes a π-π stacking interaction with the C=C double bonds of layered graphene. This non-covalent interaction significantly enhances the stability of PDA on the layered graphene surface and forms a dense polymer layer, thereby improving the dispersibility and hydrophilicity of the layered graphene. Polydopamine provides abundant polar groups, such as amino-NH2 and phenolic hydroxyl-OH, further modifying the surface of the layered graphene and significantly enhancing its surface activity.

[0031] After the in-situ growth reaction is completed, the present invention preferably includes washing and drying in sequence; the present invention has no special limitations on the washing process, and a process well known to those skilled in the art can be used to ensure that the washing is carried out to neutrality; the present invention has no special limitations on the drying process, and a process well known to those skilled in the art can be used.

[0032] In this invention, the silane coupling agent preferably includes one or more of 3-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane. When the silane coupling agent is two or more of the above-mentioned specific selections, this invention does not impose any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. In the embodiments of this invention, the silane coupling agent is specifically 3-aminopropyltriethoxysilane (APTES).

[0033] In this invention, the mass ratio of the dopamine-modified layered graphene to the silane coupling agent is preferably 1:(25~30), more preferably 1:25, 1:26, 1:27, 1:28, 1:29 or 1:30. In an embodiment of this invention, the mass ratio of the dopamine-modified layered graphene to the silane coupling agent is specifically 1:28.

[0034] In this invention, the mass ratio of the total mass of the dopamine-modified layered graphene and the silane coupling agent to the mass of the aluminum oxide is preferably 1:(1~1.5), more preferably 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, or 1:1.5. In an embodiment of this invention, the mass ratio of the total mass of the dopamine-modified layered graphene and the silane coupling agent to the mass of the aluminum oxide can be 1:1.

[0035] In this invention, the aluminum oxide has good hydrogen adsorption performance and can produce a synergistic effect against hydrogen permeation after being doped with Gr; aluminum oxide can also enhance the overall heat resistance and mechanical strength of the material, thus laying the foundation for the preparation of high-performance composite coating materials.

[0036] like Figure 1 As shown, the present invention also provides a method for preparing the composite nanomaterial described in the above technical solution, comprising the following steps: Under alkaline conditions, a layered graphene dispersion was mixed with dopamine and then subjected to an in-situ growth reaction to obtain dopamine-modified layered graphene (denoted as Gr@PDA). The dopamine-modified layered graphene was mixed with anhydrous ethanol to obtain a dopamine-modified layered graphene dispersion. The dopamine-modified layered graphene dispersion was mixed with a silane coupling agent and subjected to a hydrolysis-silane coupling reaction to obtain dopamine-modified layered graphene grafted with a silane coupling agent (denoted as Gr@PDA-APTES). Dopamine-modified layered graphene with the grafted silane coupling agent, alumina, and a dispersion medium were mixed and grafted to obtain the composite nanomaterial (denoted as Gr@PDA-APTES-Al2O3).

[0037] In this invention, unless otherwise specified, all raw materials used in the preparation are commercially available products well known to those skilled in the art.

[0038] In this invention, under alkaline conditions, a layered graphene dispersion is mixed with dopamine and then subjected to an in-situ growth reaction to obtain dopamine-modified layered graphene.

[0039] The preparation process of the dopamine-modified layered graphene in this invention refers to the preparation process of the dopamine-modified layered graphene described above, and will not be repeated here.

[0040] After obtaining the dopamine-modified layered graphene, the present invention mixes the dopamine-modified layered graphene with anhydrous ethanol to obtain a dopamine-modified layered graphene dispersion.

[0041] The present invention does not impose any special limitation on the concentration of the dopamine-modified layered graphene dispersion; any concentration known to those skilled in the art can be used.

[0042] The present invention does not impose any special limitations on the mixing process; any process well known to those skilled in the art can be used. In an embodiment of the present invention, the mixing method is specifically ultrasound, wherein the frequency of the ultrasound can be 55 Hz and the duration can be 10 minutes.

[0043] After obtaining the dopamine-modified layered graphene dispersion, the present invention mixes the dopamine-modified layered graphene dispersion with a silane coupling agent and performs a hydrolysis-silane coupling reaction to obtain dopamine-modified layered graphene grafted with a silane coupling agent.

[0044] In this invention, the mass ratio of the total mass of dopamine-modified layered graphene and silane coupling agent to the aluminum oxide in the dopamine-modified layered graphene dispersion is preferably 1:(1~1.5), more preferably 1:1, 1:1.1, 1:1.2, 1:1.3, 1:1.4, or 1:1.5. In an embodiment of this invention, the mass ratio of the total mass of the dopamine-modified layered graphene and silane coupling agent to the aluminum oxide in the dopamine-modified layered graphene dispersion can be 1:1.

[0045] In this invention, the silane coupling agent preferably includes one or more of 3-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane. When the silane coupling agent is two or more of the above-mentioned specific selections, this invention does not impose any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. In the embodiments of this invention, the silane coupling agent is specifically 3-aminopropyltriethoxysilane (APTES).

[0046] The present invention does not impose any special limitations on the mixing process; any process known to those skilled in the art can be used.

[0047] In this invention, the preferred temperature for the hydrolysis-silane coupling reaction is 65-75°C, more preferably 65°C, 66°C, 67°C, 68°C, 69°C, 70°C, 71°C, 72°C, 73°C, 74°C, or 75°C; the preferred time is 1.5-2.5 hours, more preferably 1.5 hours, 1.6 hours, 1.7 hours, 1.8 hours, 1.9 hours, 2.0 hours, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours, or 2.5 hours. In an embodiment of this invention, the specific temperature for the hydrolysis-silane coupling reaction is 70°C, and the specific time is 2 hours.

[0048] In this invention, during the hydrolysis-silane coupling reaction, the siloxy groups (Si-OH) generated from APTES during hydrolysis can couple with the amino or phenolic hydroxyl groups on the Gr@PDA surface to form strong covalent bonds. This reaction not only further enhances the interfacial bonding between Gr@PDA and APTES but also significantly improves the chemical stability of the filler. Simultaneously, the amino groups (-NH2) in the APTES molecule further improve the hydrophilicity and dispersibility of the composite material, providing active sites for subsequent binding with Al2O3.

[0049] After the hydrolysis-silane coupling reaction is completed, the present invention preferably includes sequential washing and drying. The present invention does not impose any special limitations on the washing and drying process; any process well-known to those skilled in the art can be used. In the embodiments of the present invention, the washing agent is specifically anhydrous ethanol; the drying temperature is specifically 80°C, and the drying time is specifically 1 hour.

[0050] After obtaining the dopamine-modified layered graphene grafted with the silane coupling agent, the present invention mixes the dopamine-modified layered graphene grafted with the silane coupling agent, aluminum oxide and a dispersion medium for grafting to obtain the composite nanomaterial.

[0051] In this invention, the aluminum oxide is preferably nano-sized aluminum oxide.

[0052] In this invention, the dispersion medium preferably comprises water and a polar organic solvent; the volume ratio of the polar organic solvent to water is preferably (8~15):1, more preferably 8:1, 9:1, 10:1, 11:1, 12:1, 13:1, 14:1 or 15:1. In this invention, the polar organic solvent preferably comprises one or more of ethanol, methanol, isopropanol, acetone, acetonitrile, dimethyl sulfoxide and N,N-dimethylformamide, more preferably ethanol; when the polar organic solvent is two or more of the above-mentioned specific selections, this invention does not have any special limitation on the ratio of the above-mentioned specific substances, and they can be mixed in any ratio. In the embodiments of this invention, the polar organic solvent can be ethanol.

[0053] In this invention, the grafting temperature is preferably 50~70℃, more preferably 50℃, 55℃, 60℃, 65℃ or 70℃; the grafting time is preferably 1.5~2.5h, more preferably 1.5h, 2.0h or 2.5h. In this invention, the grafting is preferably carried out under water bath and stirring conditions.

[0054] After the grafting is completed, the present invention preferably includes centrifugation and drying in sequence; the present invention does not have any special limitations on the centrifugation and drying process, and any process known to those skilled in the art can be used.

[0055] The present invention also provides the application of the composite nanomaterials described in the above technical solutions or the composite nanomaterials prepared by the preparation methods described in the above technical solutions in the preparation of hydrogen-barrier and anti-corrosion coatings.

[0056] The present invention also provides a hydrogen-barrier anti-corrosion coating, comprising epoxy resin, composite nanomaterials, curing agent and organic solvent; The composite nanomaterial is the composite nanomaterial described in the above technical solution or the composite nanomaterial prepared by the preparation method described in the above technical solution.

[0057] This invention does not impose any special limitations on the types of epoxy resin and curing agent; any types well-known to those skilled in the art can be used. In the embodiments of this invention, the epoxy resin is specifically E-44 epoxy resin; the curing agent is specifically polyamide curing agent (650). This invention does not impose any special limitations on the ratio of the epoxy resin and curing agent; any ratio well-known to those skilled in the art that can ensure the curing of the epoxy resin can be used.

[0058] In this invention, the organic solvent preferably includes ethanol. There are no special requirements for the amount of ethanol used; any amount known to those skilled in the art is sufficient to ensure the coating meets the requirements. In embodiments of this invention, when the hydrogen-barrier anti-corrosion coating is prepared by spin coating, the mass ratio of the total mass of the epoxy resin, composite nanomaterials, and curing agent to the organic solvent is preferably (10~15):1, more preferably 10:1, 11:1, 12:1, 13:1, 14:1, or 15:1.

[0059] In this invention, the mass percentage of the composite nanomaterial to the total mass of the epoxy resin, the composite nanomaterial and the curing agent is preferably 15-35%, more preferably 15%, 20%, 25%, 30% or 35%.

[0060] The present invention does not impose any special limitations on the preparation method of the hydrogen-barrier and anti-corrosion coating, and it is prepared by a mixing process well known to those skilled in the art.

[0061] The present invention also provides a hydrogen-barrier and corrosion-resistant coating, comprising an epoxy resin and a composite nanomaterial embedded in the epoxy resin; The composite nanomaterial is the composite nanomaterial described in the above technical solution or the composite nanomaterial prepared by the preparation method described in the above technical solution.

[0062] In this invention, the hydrogen-blocking and anti-corrosion coating has good resistance to hydrogen permeation and corrosion. In a high-pressure hydrogen environment, the nanocomposite filler in the coating can capture hydrogen atoms through chemical bonds and physical adsorption functions, thereby reducing the hydrogen permeability. At the same time, the sheet-like filler can effectively extend the invasion path of corrosive media and significantly enhance the anti-corrosion ability of the coating.

[0063] like Figure 2 As shown, at the physical shielding level ( Figure 2 The high specific surface area of ​​layered graphene sheets creates a dense "maze effect," significantly extending the diffusion path of hydrogen atoms. Simultaneously, nano-Al2O3 particles effectively fill the micropores and defects between the layers of graphene sheets and in the resin matrix, further blocking the continuous permeation channels of gas. The active functional groups abundant in PDA and the silane coupling agent of APTES together construct a bridge between the organic and inorganic molecular interfaces. Through the synergistic effect of covalent and hydrogen bonds, the interfacial bonding between the filler and the coating substrate is greatly enhanced, improving the coating's density and thus inhibiting hydrogen atom diffusion. Furthermore, the active adsorption and capture of hydrogen atoms by the filler is another key factor in improving barrier performance. Figure 2 (dh): On the one hand, the dangling bonds on the surface of layered graphene can react with permeated hydrogen atoms to form stable CH sp3 bonds, achieving chemical trapping. On the other hand, the abundant hydroxyl groups on the Al2O3 surface and the oxygen vacancies within its lattice provide a large number of hydrogen trapping sites. In summary, this composite coating achieves highly efficient interception of hydrogen permeation through the synergistic effect of layered physical barriers and active chemical trapping.

[0064] In this invention, the method for preparing the hydrogen-barrier and anti-corrosion coating preferably includes the following steps: The hydrogen-blocking and anti-corrosion coating described in the above technical solution is applied to the surface of a metal substrate and cured to obtain the hydrogen-blocking and anti-corrosion coating.

[0065] This invention does not impose any special limitations on the material of the metal substrate; any material well-known to those skilled in the art can be used. In the embodiments of this invention, the metal substrate is specifically a steel substrate.

[0066] Before the coating, the present invention preferably includes pretreatment of the metal substrate, which preferably includes a first cleaning, polishing, and a second cleaning performed sequentially. In the present invention, the first cleaning is preferably performed sequentially by rinsing with deionized water, degreasing with acetone, dehydrating with anhydrous ethanol, and drying. The present invention does not impose any particular limitation on the process of rinsing with deionized water, degreasing with acetone, dehydrating with anhydrous ethanol, and drying; any process well known to those skilled in the art can be used. In the present invention, the polishing is preferably performed sequentially using 400#, 800#, 1200#, and 2000# sandpaper to polish the metal substrate. In the present invention, the second cleaning is preferably performed by first cleaning the surface of the metal substrate with deionized water to remove abrasive debris, and then sequentially performing ultrasonic cleaning with acetone and anhydrous ethanol. The ultrasonic cleaning time with acetone and anhydrous ethanol is preferably 3-5 minutes, more preferably 3 minutes, 4 minutes, or 5 minutes.

[0067] In this invention, the coating is preferably performed sequentially as a first coating and a second coating. The rotation speed of the first coating is preferably 500 rpm and the time is preferably 30 s; the rotation speed of the second coating is preferably 2000 rpm and the time is preferably 30 s.

[0068] In this invention, the curing temperature is preferably 40°C and the curing time is preferably ≥12h.

[0069] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0070] Determination of in-situ growth temperature: 0.1 g of layered graphene (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and 100 mL of deionized water were ultrasonically mixed (frequency 55 Hz, time 30 min) to obtain a layered graphene dispersion (concentration 1 g / L). Under stirring conditions (1600 rpm), 0.1 g of dopamine was added to the layered graphene dispersion. The pH was adjusted to 8.5 using a 1 mol / L NaOH solution, and then an in-situ growth reaction was carried out (24 h at temperatures of 20 °C, 30 °C, 40 °C, and 50 °C) to obtain dopamine-modified layered graphene. During the in-situ growth reaction, the absorbance of each solution at 270 nm was measured using a UV-Vis spectrophotometer. Data was collected every half hour for the first 6 hours, every hour from hours 6 to 12, and every two hours from hours 12 to 24 (with the aforementioned layered graphene dispersion serving as a control group). The test results are as follows: Figure 3 As shown, Figure 3 This describes the changes in absorbance at different reaction temperatures during in-situ growth. Figure 3 As the reaction temperature increases, the absorbance values ​​at each reaction temperature gradually increase. This is because the oxidative self-polymerization of dopamine causes a gradual change in the reaction products of the system. At a reaction temperature of 20℃, the absorbance initially increases slowly, indicating a lag in the reaction process and a small amount of polydopamine generated by dopamine self-polymerization. At a reaction temperature of 30℃, the absorbance increases rapidly, indicating a relatively complete reaction and that the dopamine self-polymerization process is relatively thorough, with the polydopamine adhering to the surface of the layered graphene. At a reaction temperature of 40℃, the absorbance initially increases even faster, but fluctuates slightly in the later stages, indicating that the high temperature accelerates the oxidation reaction of dopamine (such as the formation of oxidized dopaquinone), but may also trigger some side reactions. At a reaction temperature of 50℃, the absorbance increases very rapidly, but fluctuates significantly in the later stages. The excessively high temperature leads to an overly rapid oxidation reaction, which may produce more side reactions, affecting the absorbance value and stability. As a control group, the absorbance of the layered graphene solution at room temperature remains almost unchanged. In summary, the chemical reaction process of the solution is optimal at a reaction temperature of 30℃.

[0071] Determination of pH value for in-situ growth: 0.1 g of layered graphene (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and 100 mL of deionized water were ultrasonically mixed (frequency 55 Hz, time 30 min) to obtain a layered graphene dispersion (concentration 1 g / L). Under stirring conditions (1600 rpm), 0.1 g of dopamine was added to the layered graphene dispersion. The pH value was adjusted to 7.5, 8.5 and 9.5 with 1 mol / L NaOH solution. Then, an in-situ growth reaction was carried out (24 h at 30 °C) to obtain dopamine-modified layered graphene. During the in-situ growth reaction, the absorbance of each solution at 270 nm was measured using a UV-Vis spectrophotometer. Data was collected every half hour for the first 6 hours, every hour from hours 6 to 12, and every two hours from hours 12 to 24 (a dopamine solution with an initial pH of 8.5 and a concentration of 1 g / L was used as a control group). The test results are as follows: Figure 4 As shown, Figure 4This shows the changes in absorbance under different pH conditions during in-situ growth, from... Figure 4 It was observed that the absorbance of the solution gradually increased with increasing initial pH. At an initial pH of 7.5, the absorbance of the reaction products gradually increased; at an initial pH of 8.5, the absorbance of the reaction products was enhanced, and the change in absorbance was relatively stable, ultimately reaching the highest value. At an initial pH of 9.5, the reaction rate accelerated, potentially leading to excessive oxidation of the reactants, resulting in aggregation and flocculent matter, and poor dispersibility. The control group reflected the self-polymerization process of dopamine monomers without layered graphene. During its reaction, the absorbance of the solution increased steadily, but due to the absence of layered graphene, the overall absorbance value was significantly lower than other reaction systems. The final results indicate that the reaction process was optimal at an initial pH of 8.5. Therefore, the optimal pH for DA polymerization is 8.5.

[0072] Determining the stirring speed for in-situ growth: 0.1 g of layered graphene (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and 100 mL of deionized water were ultrasonically mixed (frequency 55 Hz, time 30 min) to obtain a layered graphene dispersion (concentration 1 g / L). Under stirring conditions (300 rpm, 600 rpm, 900 rpm, 1200 rpm and 1500 rpm respectively), 0.1 g of dopamine was added to the layered graphene dispersion. After adjusting the pH value to 8.5 with a 1 mol / L NaOH solution, an in-situ growth reaction was carried out (time 24 h, temperature 30 °C) to obtain dopamine-modified layered graphene. During the in-situ growth reaction, the absorbance of each solution at 270 nm was measured using a UV-Vis spectrophotometer. Data was collected every half hour for the first 6 hours, every hour from hours 6 to 12, and every two hours from hours 12 to 24 (with the same reaction solution at no rotation speed serving as a control group). The test results are as follows: Figure 5 As shown, Figure 5 This shows the changes in absorbance under different stirring rates during in-situ growth, from... Figure 5It was observed that at stirring speeds of 0 rpm and 300 rpm, the solution exhibited distinct black and white stratification, severe agglomeration, and clumping. As the stirring speed increased to 600 rpm, the solution turned a deep brown, indicating more complete dispersion of the reaction products and a more stable internal particle distribution. Although the solution color gradually deepened, accompanied by a faster increase in absorbance in the initial stage of the reaction, a decrease in absorbance occurred in the later stages. This suggests that increased collisions between reactants may have led to significant disruption of the reaction products within the solution, resulting in a significantly increased fluctuation in the overall absorbance curve and considerable instability. The deeper color of the system indicates that excessive stirring speed only positively affects the dissolution of the layered graphene components in the solution. The final results show that a stirring speed of 600 rpm is optimal for the reaction system.

[0073] During the in-situ growth reaction, the absorbance of each solution at 270 nm was measured using a UV-Vis spectrophotometer. Data was collected every half hour for the first 6 hours, every hour from hours 6 to 12, and every two hours from hours 12 to 24 (with the same reaction solution at no rotation speed serving as a control group). The test results are as follows: Figure 5 As shown, Figure 5 This shows the changes in absorbance under different stirring rates during in-situ growth. Figure 5 It was found that without stirring, solution mass transfer was severely limited, absorbance remained almost unchanged, and surface reactions were difficult to advance. After applying moderate stirring at 300 and 600 rpm, absorbance steadily increased; the 600 rpm group maintained a relatively stable increase over 24 hours, eventually reaching the highest peak among all test groups, indicating that this speed resulted in the highest PDA generation and encapsulation efficiency. However, when the speed was further increased to the high range of 900 to 1500 rpm, absorbance exhibited an abnormal trend of first rising rapidly and then falling sharply, and the higher the speed, the earlier and more drastic the absorbance decay occurred. This is mainly attributed to the excessively strong fluid shear force intensifying collisions between reactants and accelerating the aggregation of free graphene or PDA molecules. The final results indicate that a stirring rate of 600 rpm is optimal for the reaction system.

[0074] Determining the amount of APTES to add: 0.1 g of layered graphene (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and 100 mL of deionized water were ultrasonically mixed (frequency 55 Hz, time 30 min) to obtain a layered graphene dispersion (concentration 1 g / L). Under stirring conditions (600 rpm), 0.1 g of dopamine was added to the layered graphene dispersion. The pH value was adjusted to 8.5 with a 1 mol / L NaOH solution, and then an in-situ growth reaction was carried out (24 h at 30 °C) to obtain dopamine-modified layered graphene. 0.1g of the dopamine-modified layered graphene was mixed with 100mL of anhydrous ethanol by ultrasonication (frequency 55Hz, time 10min) to obtain a dopamine-modified layered graphene dispersion with a concentration of 1g / L. The dopamine-modified layered graphene dispersion was mixed with APTES (the density of APTES can be approximately 1 g / mL, and the addition amounts are 0 mL (as a control group), 0.5 mL, 1 mL, 2 mL, 3 mL, 5 mL and 10 mL, respectively), and subjected to a hydrolysis-silane coupling reaction (at a temperature of 70 °C for 2 h). After washing with anhydrous ethanol, it was dried at 80 °C for 1 h to obtain dopamine-modified layered graphene grafted with silane coupling agent. Figure 6 Raman spectra of hydrolysis-silane coupling agent after different APTES addition amounts (focusing on the D peak (~1350 cm⁻¹)). -1 ) and G peak (~1580cm) -1 (Changes, assessing the degree of surface modification and structural defects), by Figure 6 It can be seen that when the amount of APTES added is 0.5 mL, the peak value changes less compared to the control group, indicating that the chemical reactions related to the modification process are less, and the degree of surface modification is limited. When the amount of APTES added is 2-3 mL, the ratio reaches its maximum, indicating that APTES fully modifies the surface of dopamine-modified layered graphene, the defect density reaches its maximum, and the reaction effect is optimal. This may be because APTES introduces more Si-OC and Si-N bonds during the PDA surface modification process. When the amount of APTES added reaches more than 5 mL, the ratio begins to decrease. This may be because excess APTES undergoes a self-condensation reaction, forming Si-O-Si bonds and coating the surface of layered graphene, reducing the degree of defects in the material. This leads to a decrease in the uniformity of the surface modification of dopamine-modified layered graphene, with some defects being masked or the system instability increasing. The final results show that when the amount of APTES added is 3 mL, the surface defect density is the highest, and the modification effect is optimal. Therefore, the mass ratio of APTES to dopamine-modified layered graphene should be between (25~30):1.

[0075] Examples 1-6 0.1 g of layered graphene (purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.) and 100 mL of deionized water were ultrasonically mixed (frequency 55 Hz, time 30 min) to obtain a layered graphene dispersion (concentration 1 g / L). Under stirring conditions (600 rpm), 0.1 g of dopamine was added to the layered graphene dispersion. The pH value was adjusted to 8.5 with a 1 mol / L NaOH solution, and then an in-situ growth reaction was carried out (24 h at 30 °C) to obtain dopamine-modified layered graphene. 0.1g of the dopamine-modified layered graphene was mixed with 100mL of anhydrous ethanol by ultrasonication (frequency 55Hz, time 10min) to obtain a dopamine-modified layered graphene dispersion with a concentration of 1g / L. The dopamine-modified layered graphene dispersion was mixed with 3 mL of APTES and subjected to a hydrolysis-silane coupling reaction (temperature 70℃, time 2 h). After washing with anhydrous ethanol, it was dried at 80℃ for 1 h to obtain dopamine-modified layered graphene grafted with silane coupling agent. Dopamine-modified layered graphene and nano-alumina were mixed at a mass ratio of 1:1 and dispersed in a mixed solvent of water and a polar organic solvent (volume ratio of water to polar organic solvent was 1:10, and the polar organic solvent was anhydrous ethanol). The mixture was heated and stirred in a water bath (stirring speed was 1600 rpm, temperature was 60℃, and time was 2 h). The supernatant was removed by centrifugation and the mixture was dried to obtain the composite nanomaterial. Metal substrate: 20mm in diameter, 1mm thick, made of X80 steel; The metal substrate is rinsed with deionized water, then degreased with acetone, dehydrated with anhydrous ethanol, and dried with a cold air blower. The metal substrate is then polished with sandpaper of 400#, 600#, 800#, 1200# and 2000# in sequence. The abrasive shavings on the surface of the metal substrate are cleaned with deionized water. The metal substrate is then ultrasonically cleaned with acetone and anhydrous ethanol for 3-5 minutes respectively, and dried with a cold air blower to obtain the pretreated metal substrate. E44 epoxy resin and polyamide curing agent (650) were mixed in a 1:1 mass ratio, and then anhydrous ethanol (1 wt% of the total mass of the E44 epoxy resin and polyamide curing agent) was added. The composite nanomaterials were then added (the amounts added in Examples 1 to 6 were 5%, 10%, 15%, 20%, 25%, and 30% of the total mass of the E44 epoxy resin, polyamide curing agent, and composite nanomaterials, respectively). After ultrasonic dispersion for 5 minutes, the mixture was continuously stirred to obtain a hydrogen-blocking anti-corrosion coating. The hydrogen-blocking and anti-corrosion coating was dropped onto the surface of the pretreated metal substrate and then spin-coated using a benchtop spin coater (first at 500 rpm for 30 seconds, then at 2000 rpm for 30 seconds). After that, it was dried in a 40°C oven for 12 hours to fully cure the coating, resulting in a hydrogen-blocking and anti-corrosion coating (approximately 20 μm thick). Figure 7 The images shown are cross-sectional SEM images of the hydrogen-blocking and anti-corrosion coatings described in Examples 1-6, where (a)-(b) are pure epoxy resin coatings, (c)-(d) are the hydrogen-blocking and anti-corrosion coatings described in Example 1, (e)-(f) are the hydrogen-blocking and anti-corrosion coatings described in Example 2, (g)-(h) are the hydrogen-blocking and anti-corrosion coatings described in Example 3, (i)-(g) are the hydrogen-blocking and anti-corrosion coatings described in Example 4, (k)-(l) are the hydrogen-blocking and anti-corrosion coatings described in Example 5, and (m)-(n) are the hydrogen-blocking and anti-corrosion coatings described in Example 6. Figure 7 It is understood that the hydrogen-blocking and anti-corrosion coating of the present invention has a distinct stepped structure inside the coating, and these structures play a key role in the hydrogen-blocking performance of the coating. Figure 8 This is the elemental distribution diagram of the hydrogen-barrier and anti-corrosion coating described in Example 4. Figure 9 The images show the EDS diagram and elemental percentage distribution of the hydrogen-blocking and anti-corrosion coating surface described in Example 4; (The remaining text appears to be a fragmented and incomplete sentence, possibly due to OCR errors.) Figures 8-9 As can be seen, C, N, O, Si, and Al were selected as characteristic elements during EDS detection. The C and O elements in the figure mainly originate from epoxy resin, layered graphene, and alumina; the N element mainly comes from PDA; the Si element mainly comes from APTES; and the Al element mainly comes from aluminum oxide. The hydrogen-barrier and anti-corrosion coating contains 51.4% C, 19.5% N, 22.8% O, 4.2% Si, and 2% Al by mass. This demonstrates that the composite nanomaterial has been successfully added to the hydrogen-barrier and anti-corrosion coating and is uniformly distributed.

[0076] Test case Hydrogen barrier performance test: like Figure 10 As shown in a, an electrochemical hydrogen permeation test bench was built, and an electrochemical workstation was used to test the hydrogen permeation current of X80 steel, pure epoxy resin coating (with pure E44 epoxy coating and X80 bare steel as control groups), and the hydrogen-blocking and anti-corrosion coatings described in Examples 1 to 6. Figure 10 In the figure, b represents the electrochemical hydrogen permeation curve result. The hydrogen permeation current of the X80 steel sample is as high as 26.75 × 10⁻⁶. -6 A / cm 2 The corresponding hydrogen diffusion coefficient is also as high as 10.42 × 10⁻⁶. -7 cm2 The value of / s indicates that hydrogen diffuses fastest inside the steel. In contrast, the hydrogen permeation current of the epoxy resin coated sample decreased to 18.59 × 10⁻⁶. -6 A / cm 2 With the introduction of Gr@PDA-APTES-Al2O3 particles, the hydrogen barrier performance of the composite coating was significantly improved. The hydrogen permeation currents at 5% and 10% content were 13.99 × 10⁻⁶. -6 A / cm 2 and 10.39×10 -6 A / cm 2 This indicates that Gr@PDA-APTES-Al2O3 particles effectively improve the internal density of the composite coating, fill the micropores in the system, and extend the hydrogen diffusion path. When the content is increased to 15%, the hydrogen permeation current decreases to 6.54 × 10⁻⁶. -6 A / cm 2 With a 20% content, the hydrogen permeation current of the composite coating further decreased to 2.38 × 10⁻⁶. -6 A / cm 2 With increasing particle content, the hydrogen barrier capacity of the composite coating improved by an order of magnitude compared to the X80 steel sample. However, when the particle content was further increased to 25% and 30%, the hydrogen permeation current was 9.10 × 10⁻⁶, respectively. -6 A / cm 2 and 10.34×10 -6 A / cm 2 This phenomenon indicates that particles at a content of 20% can maximally fill the pores in the composite coating and uniformly distribute to form a continuous hydrogen-barrier coating, thereby significantly delaying hydrogen permeation and exhibiting optimal hydrogen barrier performance. Excessive particles may lead to internal aggregation, compromising the structural stability of the composite coating and providing new pathways for hydrogen diffusion.

[0077] Corrosion resistance test: Electrochemical impedance spectroscopy (EIS) monitoring of X80 bare steel, X80 steel coated with pure epoxy coating (EP) (with pure E44 epoxy coating and X80 bare steel as control groups) and X80 steel coated with the hydrogen-blocking and anti-corrosion coating described in Example 4 was performed in 3.5 wt% NaCl solution for 12 days using a PARSTAT 4000A electrochemical workstation. Figure 11The following images are provided for X80 bare steel under different immersion times: Nyquist image (a), Bode image (b), Nyquist image (c), Bode image (d), Nyquist image (e), and Bode image (f) of X80 steel coated with pure epoxy (EP) coating at different immersion times. Figure 11 It can be seen that X80 bare steel ( Figure 11 In (a) to (b), the capacitive arc radius decreases significantly over time during the initial immersion stage, indicating that the matrix undergoes a rapid oxidation reaction to generate Fe. 2+ However, after immersion for 8 to 12 days, the capacitive arc showed an abnormal increase. This was attributed to the formation of a dense oxide or hydroxide deposit on the surface, producing a diffusion-limiting effect similar to Warburg impedance, but its impedance value remained consistently at 10. 3 Ω·cm 2 The magnitude is far lower than that of systems with overlay coatings. In contrast, X80 steel coated with a pure epoxy (EP) coating ( Figure 11 As the immersion time increases, the capacitive arc radius in the Nyquist plot (c~d) shows a continuously monotonically shrinking trend, while the peak phase angle in the Bode plot decreases and shifts towards lower frequencies. This phenomenon indicates that the corrosive medium (H2O, Cl)... - The hydrogen-resistant coating rapidly penetrates through the micropores within the coating, leading to increased coating capacitance and a rapid degradation of its shielding performance, failing to form effective long-term protection at the interface. In stark contrast, X80 steel coated with the hydrogen-resistant anti-corrosion coating described in Example 4... Figure 11 The ef) in the solution remained at 10 throughout the entire soaking cycle. 5 Ω·cm 2 The capacitive arc radius is on the order of magnitude. Although the impedance decreased slightly in the early stages due to the penetration of corrosive media, the phase angle of the high-frequency region of the composite coating remained close to 80°, and there was no drastic impedance attenuation as seen in the pure EP coating, demonstrating the excellent corrosion resistance and structural integrity of the coating.

[0078] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles 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 composite nanomaterial, characterized in that, Including dopamine-modified layered graphene and aluminum oxide; The dopamine-modified layered graphene and aluminum oxide are grafted together via a silane coupling agent; The composite nanomaterial is a nanosheet.

2. The composite nanomaterial as described in claim 1, characterized in that, The silane coupling agent includes one or more of 3-aminopropyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane and N-(2-aminoethyl)-3-aminopropyltrimethoxysilane. The mass ratio of layered graphene to dopamine in the dopamine-modified layered graphene is (1~1.5):

1.

3. The composite nanomaterial as described in claim 1, characterized in that, The mass ratio of the dopamine-modified layered graphene to the silane coupling agent is 1:(25~30). The total mass ratio of the dopamine-modified layered graphene and the silane coupling agent to the aluminum oxide is 1:(1~1.5).

4. The method for preparing the composite nanomaterial according to any one of claims 1 to 3, characterized in that, Includes the following steps: Under alkaline conditions, a layered graphene dispersion was mixed with dopamine and then subjected to an in-situ growth reaction to obtain dopamine-modified layered graphene. The dopamine-modified layered graphene was mixed with anhydrous ethanol to obtain a dopamine-modified layered graphene dispersion. The dopamine-modified layered graphene dispersion was mixed with a silane coupling agent and subjected to a hydrolysis-silane coupling reaction to obtain dopamine-modified layered graphene grafted with a silane coupling agent. The composite nanomaterial is obtained by grafting dopamine-modified layered graphene, alumina, and a dispersion medium together with the grafted silane coupling agent.

5. The preparation method according to claim 4, characterized in that, The alkaline conditions correspond to a pH value of 8-10, and the in-situ growth reaction is carried out at a temperature of 25-35°C for 20-24 hours. The hydrolysis-silane coupling reaction is carried out at a temperature of 65~75℃ for a time of 1.5~2.5h. The grafting temperature is 50~70℃, and the grafting time is 1.5~2.5h.

6. The application of the composite nanomaterial according to any one of claims 1 to 3 or the composite nanomaterial prepared by the preparation method according to claim 4 or 5 in the preparation of hydrogen-barrier and anti-corrosion coatings.

7. A hydrogen-barrier anti-corrosion coating, characterized in that, Including epoxy resin, composite nanomaterials, curing agents, and organic solvents; The composite nanomaterial is the composite nanomaterial according to any one of claims 1 to 3 or the composite nanomaterial prepared by the preparation method according to claim 4 or 5.

8. The hydrogen-barrier and anti-corrosion coating as described in claim 7, characterized in that, The mass percentage of the composite nanomaterial to the total mass of the epoxy resin, composite nanomaterial and curing agent is 15-35%.

9. The application of the hydrogen-barrier anti-corrosion coating according to claim 7 or 8 in the preparation of hydrogen-barrier anti-corrosion coatings.

10. A hydrogen-barrier and corrosion-resistant coating, characterized in that, Includes epoxy resin and composite nanomaterials embedded in the epoxy resin; The composite nanomaterial is the composite nanomaterial according to any one of claims 1 to 3 or the composite nanomaterial prepared by the preparation method according to claim 4 or 5.

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