A high-strength and corrosion-resistant marine aluminum alloy sheet and its processing technology

Abstract

The present invention relates to the field of aluminum alloy plates, and discloses a high-strength and corrosion-resistant marine aluminum alloy plate and its processing technology. The aluminum alloy plate includes an aluminum alloy base material and an anti-corrosion coating. The aluminum alloy base material is composed of the following raw materials in weight percentages: Si: 0.4 - 0.8%, Fe: 0.5 - 0.7%, Cu: 0.15 - 0.4%, Mn: 0.1 - 0.15%, Mg: 0.8 - 1.2%, Cr: 0.04 - 0.35%, Zn: 0.1 - 0.25%, Ti: 0.05 - 0.15%, and the balance is Al and inevitable impurities; the anti-corrosion coating includes the following raw materials in parts by weight: 40 - 65 parts of epoxy resin, 5 - 15 parts of composite nanomaterials, 3 - 7 parts of modified curing agent, 1 - 5 parts of curing agent, 1 - 3 parts of wetting agent, 0.5 - 1 part of defoaming agent, 0.1 - 1 part of leveling agent, 0.1 - 0.5 part of dispersing agent; by coating an anti-corrosion coating on the surface of the prepared aluminum alloy base material, after casting and forming, the plate is further subjected to cryogenic treatment, and composite nanomaterials and modified curing agents are added, endowing the plate with excellent impact strength, anti-corrosion performance and flame retardant performance.

Description

Technical Field

[0001] The present invention belongs to the technical field of aluminum alloy plates, and particularly relates to a high-strength and corrosion-resistant marine aluminum alloy plate and its processing technology. Background Technique

[0002] With the rapid development of the shipbuilding industry, the requirements for ship lightweighting are also increasing day by day. Aluminum alloy is widely used in the shipbuilding industry due to its advantages such as high strength, low density, high fluidity, high filling ability, good corrosion resistance, and low melting point. Since it is in the marine environment for a long time and is subjected to mechanical impact, chemical corrosion, electrochemical corrosion of seawater, and biological corrosion of planktonic microorganisms in seawater, marine aluminum alloy must have strong corrosion resistance.

[0003] Due to the relatively low corrosion potential of aluminum alloy, it is easily affected by electrochemical corrosion in a humid environment, resulting in the occurrence of electrochemical corrosion. To improve the anti-corrosion performance of aluminum alloy, using an organic coating to protect aluminum alloy is one of the relatively economical and effective methods. However, the functions of traditional coatings are single and it is difficult to meet the service needs in complex environments. In addition, in recent years, the impact resistance of aluminum alloy has received extensive attention. Thin-walled aluminum alloy structures such as the bottom and side of ships may be subjected to the action of low-speed impact loads such as collision, grounding, and reef impact during their service life, resulting in irreversible plastic deformations such as impact pits in the ship structure. Summary of the Invention

[0004] To solve the deficiencies mentioned in the above background technique, the purpose of the present invention is to provide a high-strength and corrosion-resistant marine aluminum alloy plate and its processing technology. By coating an anti-corrosion coating on the surface of the prepared aluminum alloy substrate, and after casting and forming, the plate is further subjected to cryogenic treatment, which significantly improves the overall corrosion resistance and strength of the aluminum alloy plate, and the composite nanomaterials and modified curing agents added in the anti-corrosion coating endow the aluminum alloy plate with excellent impact strength, anti-corrosion performance, and flame retardant performance.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A high-strength and corrosion-resistant marine aluminum alloy plate, comprising an aluminum alloy substrate and an anti-corrosion coating coated on the surface of the aluminum alloy substrate. The aluminum alloy substrate is composed of the following raw materials in weight percentages: Si: 0.4 - 0.8%, Fe: 0.5 - 0.7%, Cu: 0.15 - 0.4%, Mn: 0.1 - 0.15%, Mg: 0.8 - 1.2%, Cr: 0.04 - 0.35%, Zn: 0.1 - 0.25%, Ti: 0.05 - 0.15%, and the balance is Al and inevitable impurities; the anti-corrosion coating comprises the following raw materials in parts by weight: 40 - 65 parts of epoxy resin, 5 - 15 parts of composite nanomaterial, 3 - 7 parts of modified curing agent, 1 - 5 parts of curing agent, 1 - 3 parts of wetting agent, 0.5 - 1 part of defoaming agent, 0.1 - 1 part of leveling agent, and 0.1 - 0.5 part of dispersant;

[0007] The composite nanomaterial is prepared by functionalizing activated montmorillonite with octadecyltrimethoxysilane and cage-like silsesquioxane, further loading zinc ions by electrostatic adsorption, and then self-assembling with modified carbon nanotubes to form a composite nanomaterial. The activated montmorillonite is prepared by treating with γ-aminopropyltriethoxysilane and succinic anhydride, and the modified carbon nanotubes are prepared by subjecting carboxylated carbon nanotubes to amidation reaction and protonic acid salification reaction with triethylenetetramine; the modified curing agent is prepared by reacting the flame retardant (2,4-dimethylphenyl)phenylphosphine oxide with 1,5-naphthalenediamine and terephthalaldehyde through a chemical reaction.

[0008] Preferably, the curing agent is polyamide; the wetting agent is polydimethylsiloxane; the defoaming agent is one of fatty alcohol polyoxyethylene ether or alkylphenol polyoxyethylene ether; the leveling agent is sodium polyacrylate; the dispersant is one of BYK-190 or BYK-191.

[0009] Preferably, the preparation method of the composite nanomaterial comprises the following steps:

[0010] (1) Take N,N-diisopropylcarbodiimide, 1-hydroxybenzotriazole, and carboxylated carbon nanotubes and add them to N,N-dimethylformamide, ultrasonically disperse them evenly, then add triethylenetetramine and stir for 20 - 24 h. After the reaction is completed, filter and wash, and ultrasonically disperse the obtained product in deionized water. Dropwise add hydrochloric acid solution under stirring and stir for 0.5 - 1 h to prepare modified carbon nanotubes;

[0011] (2) Take γ-aminopropyltriethoxysilane and succinic anhydride in N,N-dimethylformamide, place them at 75 - 90 °C and stir for 2 - 4 h to form a mixed solution. Take montmorillonite and ultrasonically disperse it in N,N-dimethylformamide, add deionized water and mix, then add it to the mixed solution and continue to stir for 3 - 5 h. After the reaction is completed, centrifuge, wash, and dry to prepare activated montmorillonite;

[0012] (3) Take deionized water, propanol, acetonitrile and tetraethylammonium hydroxide in a reactor, add γ-aminopropyltriethoxysilane, and place it under stirring reaction at 45 - 55 °C for 20 - 24 h. After the reaction is completed, carry out rotary evaporation, washing and drying to prepare cage-shaped silsesquioxane;

[0013] (4) Take activated montmorillonite and ultrasonically disperse it in absolute ethanol, add tetraethyl orthosilicate and octadecyltrimethoxysilane, place it under stirring reaction at 45 - 60 °C for 8 - 12 h, then raise the temperature to 170 - 180 °C, add cage-shaped silsesquioxane and paraformaldehyde, and continue stirring reaction for 14 - 16 h. After the reaction is completed, carry out centrifugation, washing and drying to prepare functionalized montmorillonite;

[0014] (5) Take functionalized montmorillonite and ultrasonically disperse it in deionized water, then add zinc nitrate and place it under stirring reaction at 55 - 70 °C for 3 - 4 h. After the reaction is completed, carry out centrifugation, washing and drying to prepare modified montmorillonite;

[0015] (6) Take modified montmorillonite and ultrasonically disperse it in deionized water, place it under stirring at 75 - 85 °C for 15 - 30 min, then add modified carbon nanotubes and continue stirring reaction for 20 - 24 h. After the reaction is completed, carry out filtration, washing and drying to prepare the composite nanomaterial.

[0016] Preferably, in the step (4), the addition ratio of activated montmorillonite, tetraethyl orthosilicate, octadecyltrimethoxysilane and cage-shaped silsesquioxane is 3 g : 2 - 3 mL : 1 - 2 mL : 10 - 16 g.

[0017] Preferably, in the step (5), the mass ratio of functionalized montmorillonite to zinc nitrate is 1 : 1.5 - 2.

[0018] Preferably, in the step (6), the mass ratio of modified montmorillonite to modified carbon nanotubes is 10 - 15 : 1.

[0019] Preferably, the preparation method of the modified curing agent comprises the following steps:

[0020] A. Take phenyl dichlorophosphine in a reactor, add m-xylene and anhydrous aluminum chloride, raise the temperature to 70 - 85 °C and react for 8 - 12 h. After the reaction is completed, cool to room temperature, add hydrochloric acid and benzene for hydrolysis, separate out the organic layer, extract the aqueous layer with benzene again, combine the organic layers, wash with deionized water, and remove the organic solvent by vacuum evaporation to prepare (2,4-dimethylphenyl)phenylphosphine oxide flame retardant;

[0021] B. Take 1,5-naphthalenediamine in a reactor, add ethanol solvent and disperse evenly. Dissolve terephthalaldehyde in ethanol and then add it to the reactor. Place it under reflux at 50 - 75 °C for 4 - 6 h. Then dissolve (2,4-dimethylphenyl)phenylphosphine oxide flame retardant in ethanol and add it to the reactor. Raise the temperature to 75 - 85 °C and react for 5 - 7 h. After the reaction is completed, filter, wash and dry to prepare the modified curing agent.

[0022] Preferably, in step A, the mass ratio of phenyl dichloride, m-xylene and anhydrous aluminum chloride is 1:0.5 - 0.7:0.5 - 0.8.

[0023] Preferably, in step B, the mass ratio of 1,5-naphthalenediamine, terephthalaldehyde and (2,4-dimethylphenyl)phenylphosphine oxide flame retardant is 2.3 - 2.7:1:3.4 - 4.1.

[0024] The processing technology of the high-strength and corrosion-resistant marine aluminum alloy plate as described above includes the following steps:

[0025] S1. Weigh each element ingredient by weight percentage and put it into a melting furnace. Set the temperature in the furnace to 750 - 800 °C. After all the materials in the furnace are melted, stir evenly for 30 - 45 min. After stirring ends, raise the temperature to 850 °C and keep it static and insulated for 10 - 20 min. Skim the slag and take samples for analysis, detect and adjust the alloy composition to obtain the alloy material.

[0026] S2. Refine the alloy material. Set the refining temperature to 700 - 730 °C and the refining time to 20 - 25 min. After refining, keep it static for 15 - 20 min. Then carry out casting to obtain a slab, and then conduct heat treatment, keep it at 150 - 180 °C for 4 - 8 h to obtain the aluminum alloy slab.

[0027] S3. Carry out hot rolling treatment on the aluminum alloy slab. Raise the temperature from 180 - 220 °C to 250 - 280 °C, then keep it warm for 5 - 7 h. Then carry out cold rolling treatment. The inlet rolling temperature is 300 - 350 °C and the final rolling temperature is 220 - 250 °C. Clean and dry the slab after hot rolling and cold rolling treatments to obtain the aluminum alloy base material.

[0028] S4. Take weight parts of epoxy resin, modified curing agent, composite nanomaterial, curing agent, wetting agent, defoaming agent, leveling agent and dispersant and put them into a high-speed disperser for stirring and dispersing. Raise the temperature to 120 - 150 °C and disperse evenly for 30 - 50 min, then take out to prepare the anti-corrosion coating. Then evenly coat the anti-corrosion coating on the surface of the aluminum alloy base material, and after drying and cooling, obtain the anti-corrosion aluminum alloy plate.

[0029] S5. Immerse the anti-corrosion aluminum alloy sheet in hydrogen peroxide solution in a deep freezer for 10 - 20 min. After taking it out, keep it at -10°C for 20 - 30 min, then keep it at -40°C for 10 - 20 min, and then keep it at -90°C for 30 - 40 min. After taking it out of the deep freezer, let it return to room temperature naturally in the air and place it for 1 - 2 h to obtain a high-strength and corrosion-resistant marine aluminum alloy sheet.

[0030] Advantages of the present invention:

[0031] The aluminum alloy sheet prepared by the present invention has excellent strength, elongation performance and corrosion resistance, can effectively meet the application requirements of ships for high-strength and corrosion-resistant aluminum alloy sheets, and a corrosion prevention coating is coated on the surface of the aluminum alloy substrate after preparation. After casting and forming, the sheet is further cryogenically treated, significantly improving the overall corrosion resistance and strength of the aluminum alloy sheet, effectively avoiding corrosion caused by external factors such as acid rain and smog, and extending the service life of the aluminum alloy sheet.

[0032] In the present invention, modified carbon nanotubes are obtained after the amidation reaction and protonic acid salt formation reaction between carboxylated carbon nanotubes and triethylenetetramine. At the same time, the surface of montmorillonite is activated by γ-aminopropyltriethoxysilane and succinic anhydride, making the surface of montmorillonite rich in hydroxyl and carboxyl groups. Then, octadecyltrimethoxysilane and cage-like silsesquioxane are used to functionalize the activated montmorillonite. Octadecyltrimethoxysilane-functionalized montmorillonite endows the coating with superhydrophobic properties, and cage-like silsesquioxane with amino groups is grafted into the interlayer of montmorillonite, improving the dispersion performance of montmorillonite and further loading zinc ions through electrostatic adsorption to prepare modified montmorillonite. Through the synergistic effect of octadecyltrimethoxysilane, cage-like silsesquioxane, montmorillonite and zinc oxide, the coating is endowed with excellent corrosion prevention and hydrophobicity. At the same time, zinc oxide has good light and heat resistance, and it forms a coordination compound with carboxylate ions in the coating, thereby reducing the water sensitivity of the coating and improving the weather resistance of the coating. Then, one-dimensional tubular modified carbon nanotubes and two-dimensional layered modified montmorillonite are self-assembled to form a composite nanomaterial. The ammonium salt cations on the surface of the modified carbon nanotubes are 2+ , Ca 2+ and other cations are exchanged, enabling them to enter the crystal structure of the modified montmorillonite, and further realizing the combination of the modified montmorillonite and the modified carbon nanotubes in the form of ionic bonds, playing a synergistic strengthening and toughening effect, and enhancing the chloride ion impermeability.

[0033] The present invention utilizes the reaction of phenyl dichlorophosphine with m-xylene to prepare the flame retardant (2,4-dimethylphenyl)phenylphosphine oxide. Then, the flame retardant (2,4-dimethylphenyl)phenylphosphine oxide is reacted with 1,5-naphthalenediamine and terephthalaldehyde. Among them, 1,5-naphthalenediamine has good thermal stability and can release smoke and flame-retardant gases that inhibit combustion at high temperatures. One end amino group in the structure of 1,5-naphthalenediamine reacts with the aldehyde groups at both ends of terephthalaldehyde to form N=C bonds. Then, the P-H bond in the structure of the flame retardant (2,4-dimethylphenyl)phenylphosphine oxide undergoes an addition reaction with the N=C bond to prepare a modified curing agent, which is added to the anti-corrosion coating to endow the coating with excellent flame retardant properties. Detailed implementation mode

[0034] The following will combine the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention.

[0035] In the examples and comparative examples of the present invention, the carboxylated carbon nanotubes have a diameter of 20 - 40 nm and a length of 30 μm, and are purchased from Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences; montmorillonite is purchased from Zhejiang Fenghong New Materials Co., Ltd.; the epoxy resin has a viscosity of 1200 - 1400 mPa·s at 25°C and is purchased from Lianyungang Zhongfu Lianzhong Composite Materials Group Co., Ltd.

[0036] Example 1 A preparation method of a composite nanomaterial includes the following steps:

[0037] (1) Take 0.02 g of N,N-diisopropylcarbodiimide, 0.02 g of 1-hydroxybenzotriazole, and 1 g of carboxylated carbon nanotubes and add them to 100 mL of N,N-dimethylformamide. After ultrasonic dispersion, 0.5 g of triethylenetetramine is added and stirred for 24 h. After the reaction is completed, it is filtered and washed, and the obtained product is ultrasonically dispersed in 100 mL of deionized water. While stirring, 10 mL of 6 mol / L hydrochloric acid solution is added dropwise and stirred for 0.5 h to prepare modified carbon nanotubes;

[0038] (2) Take 3.6 g of γ-aminopropyltriethoxysilane and 4.7 g of succinic anhydride in 100 mL of N,N-dimethylformamide, place it at 80°C and stir for 4 h to form a mixed solution. Take 3 g of montmorillonite and ultrasonically disperse it in 100 mL of N,N-dimethylformamide, add 15 mL of deionized water and mix, then add it to the mixed solution and continue to stir for 4 h. After the reaction is completed, it is centrifuged, washed, and dried to prepare activated montmorillonite;

[0039] (3) Take 45 g of deionized water, 20 mL of propanol, 5 mL of acetonitrile and 1 mL of tetraethylammonium hydroxide in a reactor, add 110.5 g of γ-aminopropyltriethoxysilane, place it at 50 °C and stir for reaction for 24 h. After the reaction is completed, carry out rotary evaporation, washing and drying to prepare cage-shaped silsesquioxane;

[0040] (4) Take 3 g of activated montmorillonite and ultrasonically disperse it in 40 mL of absolute ethanol. Add 3 mL of tetraethyl orthosilicate and 2 mL of octadecyltrimethoxysilane, place it at 50 °C and stir for reaction for 10 h. Then raise the temperature to 175 °C, add 15.4 g of cage-shaped silsesquioxane and 0.17 g of paraformaldehyde, and continue to stir for reaction for 16 h. After the reaction is completed, carry out centrifugation, washing and drying to prepare functionalized montmorillonite;

[0041] (5) Take 7 g of functionalized montmorillonite and ultrasonically disperse it in 200 mL of deionized water, then add 10.8 g of zinc nitrate and stir for reaction at 65 °C for 4 h. After the reaction is completed, carry out centrifugation, washing and drying to prepare modified montmorillonite;

[0042] (6) Take 10.2 g of modified montmorillonite and ultrasonically disperse it in 200 mL of deionized water, place it at 80 °C and stir for 25 min, then add 1 g of modified carbon nanotubes and continue to stir for reaction for 24 h. After the reaction is completed, carry out filtration, washing and drying to prepare the composite nanomaterial.

[0043] Example 2 A preparation method of a modified curing agent includes the following steps:

[0044] A. Take 8 g of phenylphosphorus dichloride in a reactor, add 4.6 g of m-xylene and 5.3 g of anhydrous aluminum chloride, raise the temperature to 75 °C and react for 10 h. After the reaction is completed, cool to room temperature, add 20 mL of 10 wt% hydrochloric acid and 40 mL of benzene for hydrolysis, separate the organic layer, extract the aqueous layer with 40 mL of benzene again, combine the organic layers, wash with deionized water, and distill off the organic solvent under reduced pressure to prepare (2,4-dimethylphenyl)phenylphosphine oxide flame retardant;

[0045] B. Take 9.2 g of 1,5-naphthalenediamine in a reactor, add 50 mL of ethanol solvent and disperse it evenly. Take 4 g of terephthalaldehyde dissolved in 50 mL of ethanol and add it to the reactor, place it at 60 °C and reflux for reaction for 5 h. Then take 13.6 g of (2,4-dimethylphenyl)phenylphosphine oxide flame retardant dissolved in 100 mL of ethanol and add it to the reactor, raise the temperature to 80 °C and react for 7 h. After the reaction is completed, carry out filtration, washing and drying to prepare the modified curing agent.

[0046] Example 3. A high-strength and corrosion-resistant marine aluminum alloy sheet, comprising an aluminum alloy substrate and an anti-corrosion coating coated on the surface of the aluminum alloy substrate. The aluminum alloy substrate is composed of the following raw materials by weight percentage: Si: 0.4%, Fe: 0.5%, Cu: 0.2%, Mn: 0.1%, Mg: 0.85%, Cr: 0.04%, Zn: 0.15%, Ti: 0.05%, and the balance is Al and inevitable impurities; the anti-corrosion coating comprises the following raw materials by weight: 41 parts of epoxy resin, 5 parts of the composite nanomaterial prepared in Example 1, 3 parts of the modified curing agent prepared in Example 2, 1 part of curing agent polyamide, 1 part of wetting agent polydimethylsiloxane, 0.5 part of defoaming agent fatty alcohol polyoxyethylene ether, 0.2 part of leveling agent sodium polyacrylate, and 0.1 part of dispersant BYK-190.

[0047] The processing technology of the above high-strength and corrosion-resistant marine aluminum alloy sheet comprises the following steps:

[0048] S1. Weigh each element ingredient according to the weight percentage and put them into a melting furnace. The temperature in the furnace is set at 780 °C. After all the materials in the furnace are melted, stir evenly for 30 min. After the stirring ends, raise the temperature to 850 °C and keep it warm for 20 min. Then skim the slag and take samples for analysis, detect and adjust the alloy composition to obtain alloy materials.

[0049] S2. Refine the alloy materials. The refining temperature is set at 720 °C and the refining time is 20 min. After refining, let it stand for 20 min, and then carry out casting. The slab is obtained by casting, and then heat treatment is carried out. Keep it warm at 175 °C for 8 h to obtain an aluminum alloy slab.

[0050] S3. Carry out hot rolling treatment on the aluminum alloy slab. Raise the temperature from 185 °C to 260 °C, then keep it warm for 5 h, and then carry out cold rolling treatment. The rolling-in temperature is 320 °C and the final rolling temperature is 230 °C. Clean and dry the slab after hot rolling and cold rolling treatments to obtain an aluminum alloy substrate.

[0051] S4. Take the epoxy resin, modified curing agent, composite nanomaterial, curing agent, wetting agent, defoaming agent, leveling agent and dispersant by weight and put them into a high-speed disperser for stirring and dispersing. After raising the temperature to 145 °C and evenly dispersing for 35 min, take them out to prepare the anti-corrosion coating. Then evenly coat the anti-corrosion coating on the surface of the aluminum alloy substrate, and after drying and cooling, obtain the anti-corrosion aluminum alloy sheet.

[0052] S5. Immerse the anti-corrosion aluminum alloy sheet in hydrogen peroxide in a deep-freezer for 15 min, take it out and keep it warm at -10 °C for 20 min, then keep it warm at -40 °C for 15 min, and then keep it at -90 °C for 40 min and take it out of the deep-freezer, and place it in the air to naturally return to room temperature and place it for 2 h to obtain the high-strength and corrosion-resistant marine aluminum alloy sheet.

[0053] Example 4. A high-strength and corrosion-resistant marine aluminum alloy sheet, comprising an aluminum alloy substrate and an anti-corrosion coating coated on the surface of the aluminum alloy substrate. The aluminum alloy substrate is composed of the following raw materials in weight percentages: Si: 0.7%, Fe: 0.6%, Cu: 0.35%, Mn: 0.12%, Mg: 0.98%, Cr: 0.22%, Zn: 0.2%, Ti: 0.1%, and the balance is Al and inevitable impurities; the anti-corrosion coating comprises the following raw materials in parts by weight: 52 parts of epoxy resin, 10 parts of the composite nanomaterial prepared in Example 1, 5 parts of the modified curing agent prepared in Example 2, 3 parts of curing agent polyamide, 2 parts of wetting agent polydimethylsiloxane, 0.7 part of defoaming agent alkylphenol polyoxyethylene ether, 0.5 part of leveling agent sodium polyacrylate, and 0.3 part of dispersant BYK-191.

[0054] The processing technology of the above high-strength and corrosion-resistant marine aluminum alloy sheet is the same as that of Example 3.

[0055] Example 5. A high-strength and corrosion-resistant marine aluminum alloy sheet, comprising an aluminum alloy substrate and an anti-corrosion coating coated on the surface of the aluminum alloy substrate. The aluminum alloy substrate is composed of the following raw materials in weight percentages: Si: 0.8%, Fe: 0.7%, Cu: 0.4%, Mn: 0.14%, Mg: 1.2%, Cr: 0.33%, Zn: 0.22%, Ti: 0.14%, and the balance is Al and inevitable impurities; the anti-corrosion coating comprises the following raw materials in parts by weight: 62 parts of epoxy resin, 15 parts of the composite nanomaterial prepared in Example 1, 7 parts of the modified curing agent prepared in Example 2, 5 parts of curing agent polyamide, 3 parts of wetting agent polydimethylsiloxane, 1 part of defoaming agent alkylphenol polyoxyethylene ether, 1 part of leveling agent sodium polyacrylate, and 0.5 part of dispersant BYK-191.

[0056] The processing technology of the above high-strength and corrosion-resistant marine aluminum alloy sheet is the same as that of Example 3.

[0057] Comparative Example 1. A preparation method of a composite nanomaterial comprises the following steps:

[0058] (1) Take 0.02 g of N,N-diisopropylcarbodiimide, 0.02 g of 1-hydroxybenzotriazole and 1 g of carboxylated carbon nanotubes and add them to 100 mL of N,N-dimethylformamide, ultrasonically disperse evenly, then add 0.5 g of triethylenetetramine and stir for reaction for 24 h. After the reaction is completed, filter and wash, ultrasonically disperse the obtained product in 100 mL of deionized water, dropwise add 10 mL of 6 mol / L hydrochloric acid solution under stirring and stir for 0.5 h to prepare modified carbon nanotubes;

[0059] (2) 10.2 g of montmorillonite was ultrasonically dispersed in 200 mL of deionized water, stirred at 80 °C for 25 min, then 1 g of modified carbon nanotubes was added and the stirring reaction continued for 24 h. After the reaction was completed, it was filtered, washed, and dried to prepare a composite nanomaterial.

[0060] Comparative Example 2 A method for preparing a composite nanomaterial includes the following steps:

[0061] (1) 0.02 g of N,N - diisopropylcarbodiimide, 0.02 g of 1 - hydroxybenzotriazole, and 1 g of carboxylated carbon nanotubes were added to 100 mL of N,N - dimethylformamide, ultrasonically dispersed evenly, then 0.5 g of triethylenetetramine was added and the stirring reaction continued for 24 h. After the reaction was completed, it was filtered and washed, and the obtained product was ultrasonically dispersed in 100 mL of deionized water, and 10 mL of 6 mol / L hydrochloric acid solution was added dropwise under stirring and stirred for 0.5 h to prepare modified carbon nanotubes;

[0062] (2) 3.6 g of γ - aminopropyltriethoxysilane and 4.7 g of succinic anhydride were placed in 100 mL of N,N - dimethylformamide, stirred at 80 °C for 4 h to form a mixed solution. 3 g of montmorillonite was ultrasonically dispersed in 100 mL of N,N - dimethylformamide, mixed with 15 mL of deionized water, and then added to the mixed solution and stirred for another 4 h. After the reaction was completed, it was centrifuged, washed, and dried to prepare activated montmorillonite;

[0063] (3) 45 g of deionized water, 20 mL of propanol, 5 mL of acetonitrile, and 1 mL of tetraethylammonium hydroxide were placed in a reactor, 110.5 g of γ - aminopropyltriethoxysilane was added, and the stirring reaction was carried out at 50 °C for 24 h. After the reaction was completed, it was rotary evaporated, washed, and dried to prepare cage - type silsesquioxane;

[0064] (4) 3 g of activated montmorillonite was ultrasonically dispersed in 40 mL of absolute ethanol, 3 mL of tetraethyl orthosilicate and 2 mL of octadecyltrimethoxysilane were added, stirred at 50 °C for 10 h, then the temperature was raised to 175 °C, 15.4 g of cage - type silsesquioxane and 0.17 g of paraformaldehyde were added, and the stirring reaction continued for 16 h. After the reaction was completed, it was centrifuged, washed, and dried to prepare functionalized montmorillonite;

[0065] (5) 10.2 g of functionalized montmorillonite was ultrasonically dispersed in 200 mL of deionized water, stirred at 80 °C for 25 min, then 1 g of modified carbon nanotubes was added and the stirring reaction continued for 24 h. After the reaction was completed, it was filtered, washed, and dried to prepare a composite nanomaterial.

[0066] Comparative Example 3: A high-strength and corrosion-resistant marine aluminum alloy sheet, in which the composite nanomaterial prepared in Example 1 added to the anti-corrosion coating in Example 5 is replaced in equal amount with the composite nanomaterial prepared in Comparative Example 1, and the other components are the same as in Example 5.

[0067] The processing technology of the above high-strength and corrosion-resistant marine aluminum alloy sheet is the same as that in Example 3.

[0068] Comparative Example 4: A high-strength and corrosion-resistant marine aluminum alloy sheet, in which the composite nanomaterial prepared in Example 1 added to the anti-corrosion coating in Example 5 is replaced in equal amount with the composite nanomaterial prepared in Comparative Example 2, and the other components are the same as in Example 5.

[0069] The processing technology of the above high-strength and corrosion-resistant marine aluminum alloy sheet is the same as that in Example 3.

[0070] Comparative Example 5: A high-strength and corrosion-resistant marine aluminum alloy sheet, in which the modified curing agent prepared in Example 2 added to the anti-corrosion coating in Example 5 is replaced in equal amount with the curing agent polyamide, and the other components are the same as in Example 5.

[0071] The processing technology of the above high-strength and corrosion-resistant marine aluminum alloy sheet is the same as that in Example 3.

[0072] Performance Testing

[0073] The high-strength and corrosion-resistant marine aluminum alloy sheets prepared in Examples 3 - 5 and Comparative Examples 3 - 5 were subjected to performance testing: Referring to GB / T 16865-2013, the aluminum alloy sheets were processed into standard tensile specimens, and tensile tests were carried out at room temperature on a DNS200 type electronic tensile testing machine with a tensile rate of 2 mm / min for tensile mechanical property testing; a contact angle measuring instrument was used to measure the water contact angle of the coating; the surface of the aluminum alloy was marked with "×", and then placed in a salt spray test chamber for salt spray aging testing. 5% NaCl solution was used as the spray medium, the test temperature was maintained at (35 ± 2) °C, the pH value was about 6.7 - 7.5, and a continuous spray method was used for the coating salt spray resistance test; referring to GB / T 1843-2008, an impact strength tester for cantilever beam was used to test the impact resistance of the aluminum alloy coating; the flame retardant performance was tested through the limiting oxygen index, and the data results are shown in Table 1.

[0074] Table 1 Test Results of Specimen Performance

[0075]

[0076] As can be seen from the data in Table 1, the aluminum alloy sheets prepared in Examples 3-5 of the present invention have excellent strength, elongation performance, impact resistance, corrosion resistance and flame retardancy. Among them, the water contact angle, impact resistance and corrosion potential measured in Comparative Example 3 are lower than those in Examples 3-5, and bubbles and corrosion products appear on the coating surface, indicating that functionalizing activated montmorillonite with octadecyltrimethoxysilane and cage-like silsesquioxane and loading zinc ions can improve the corrosion resistance and impact strength of the aluminum alloy coating. Bubbles appear on the coating surface measured in Comparative Example 4, and the corrosion potential is reduced to -0.19, indicating that the loading of zinc ions can further improve the corrosion resistance of the aluminum alloy coating. The limiting oxygen index measured in Comparative Example 5 is significantly lower than that in Examples 3-5, because a modified curing agent with flame retardancy is not added.

[0077] In the description of this specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0078] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art of this industry should understand that the present invention is not limited by the above embodiments, and the above embodiments and the descriptions in the specification only illustrate the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed.

Claims

1. A high-strength, corrosion-resistant marine aluminum alloy plate, characterized in that: It includes an aluminum alloy substrate and an anti-corrosion coating coated on the surface of the aluminum alloy substrate, wherein the aluminum alloy substrate is composed of the following raw materials in weight percentage: Composition: Si: 0.4-0.8%, Fe: 0.5-0.7%, Cu: 0.15-0.4%, Mn: 0.1-0.15%, Mg: 0.8-1.2%, Cr: 0.04-0.35%, Zn: 0.1-0.25%, Ti: 0.05-0.15%, the balance is Al and inevitable impurities; the anti-corrosion coating comprises the following raw materials in parts by weight: 40-65 parts of epoxy resin, 5-15 parts of composite nanomaterials, 3-7 parts of modified curing agent, 1-5 parts of curing agent, 1-3 parts of wetting agent, 0.5-1 part of defoaming agent, 0.1-1 part of leveling agent, 0.1-0.5 part of dispersant; The composite nano material is prepared by functionalizing activated montmorillonite with octadecyltrimethoxysilane and cage-type silsesquioxane, further loading zinc ions through electrostatic adsorption, and then self-assembling with modified carbon nanotubes to form the composite nano material, wherein the activated montmorillonite is prepared by treating with γ-aminopropyltriethoxysilane and succinic anhydride, and the modified carbon nanotubes are prepared by amidation reaction of carboxylated carbon nanotubes with triethylenetetramine and proton acid salt formation reaction; and the modified curing agent is prepared by reacting a flame retardant (2,4-xylyl)phenylphosphine oxide with 1,5-naphthalenediamine and terephthalaldehyde through a chemical reaction.

2. The high-strength, corrosion-resistant marine aluminum alloy sheet according to claim 1, characterized in that: The curing agent is polyamide; the wetting agent is polydimethylsiloxane; the defoaming agent is one of fatty alcohol polyoxyethylene ether or alkylphenol polyoxyethylene ether; the leveling agent is sodium polyacrylate; and the dispersant is one of BYK-190 or BYK-191.

3. The high-strength, corrosion-resistant marine aluminum alloy sheet according to claim 1, characterized in that: The preparation method of the composite nanomaterial comprises the following steps: (1) N, N-diisopropylcarbodiimide, 1-hydroxybenzotriazole and carboxylated carbon nanotubes are added to N, N-dimethylformamide, and ultrasonically dispersed uniformly. Then, triethylenetetramine is added and stirred for 20 to 24 hours. After the reaction is completed, the product is filtered and washed, and ultrasonically dispersed in deionized water. Hydrochloric acid solution is added dropwise under stirring and stirred for 0.5 to 1 hour to prepare modified carbon nanotubes; (2) taking γ-aminopropyltriethoxysilane and succinic anhydride in N,N-dimethylformamide, stirring at 75-90° C. for 2-4 hours to form a mixed solution, ultrasonically dispersing montmorillonite in N,N-dimethylformamide, adding deionized water to mix, and then adding it to the mixed solution and continuing to stir for 3-5 hours. After the reaction is completed, centrifuging, washing, and drying are performed to prepare activated montmorillonite; (3) Deionized water, propanol, acetonitrile and tetraethylammonium hydroxide are placed in a reactor, γ-aminopropyltriethoxysilane is added, and the mixture is stirred at 45 to 55° C. for 20 to 24 hours. After the reaction is completed, the mixture is subjected to rotary evaporation, washing and drying to prepare a cage-type silsesquioxane; (4) taking activated montmorillonite and dispersing it in anhydrous ethanol by ultrasonic, adding tetraethyl silicate and octadecyltrimethoxysilane, stirring and reacting at 45-60° C. for 8-12 hours, then heating to 170-180° C., adding cage-type silsesquioxane and polyformaldehyde, and continuing to stir and react for 14-16 hours. After the reaction is completed, centrifugation, washing, and drying are performed to prepare functionalized montmorillonite; (5) ultrasonically dispersing the functionalized montmorillonite in deionized water, then adding zinc nitrate and stirring the mixture at 55-70° C. for 3-4 hours. After the reaction is completed, the mixture is centrifuged, washed, and dried to obtain a modified montmorillonite. (6) The modified montmorillonite is ultrasonically dispersed in deionized water, stirred at 75-85° C. for 15-30 min, and then the modified carbon nanotubes are added and stirred for 20-24 h. After the reaction is completed, the composite nanomaterial is prepared by filtering, washing, and drying.

4. The high-strength, corrosion-resistant marine aluminum alloy sheet according to claim 3, characterized in that: In the step (4), the addition ratio of activated montmorillonite, tetraethyl silicate, octadecyltrimethoxysilane and cage-type silsesquioxane is 3 g: 2-3 mL: 1-2 mL: 10-16 g.

5. The high-strength, corrosion-resistant marine aluminum alloy sheet according to claim 3, characterized in that: In the step (5), the mass ratio of the functionalized montmorillonite to zinc nitrate is 1:1.5-2.

6. The high-strength, corrosion-resistant marine aluminum alloy sheet according to claim 3, characterized in that: In the step (6), the mass ratio of the modified montmorillonite to the modified carbon nanotubes is 10-15:

1.

7. The high-strength, corrosion-resistant marine aluminum alloy sheet according to claim 1, characterized in that: The preparation method of the modified curing agent comprises the following steps: A. Phenyl phosphorus dichloride is placed in a reactor, m-xylene and anhydrous aluminum chloride are added, the temperature is raised to 70-85° C. for reaction for 8-12 hours, after the reaction is completed, the reaction is cooled to room temperature, hydrochloric acid and benzene are added for hydrolysis, the organic layer is separated, the aqueous layer is extracted with benzene, the organic layers are combined, washed with deionized water, and the organic solvent is evaporated under reduced pressure to prepare (2,4-xylyl)phenyl phosphorus oxide flame retardant; B. Take 1,5-naphthalenediamine in a reactor, add ethanol solvent to disperse it evenly, take terephthalaldehyde dissolved in ethanol and add it to the reactor, place it at 50-75°C for reflux reaction for 4-6 hours, then take (2,4-xylyl)phenylphosphine oxide flame retardant dissolved in ethanol and add it to the reactor, heat it to 75-85°C for reaction for 5-7 hours, and after the reaction is completed, filter, wash and dry it to prepare a modified curing agent.

8. The high-strength, corrosion-resistant marine aluminum alloy sheet according to claim 7, characterized in that: In the step A, the mass ratio of phenylphosphonium dichloride, m-xylene and anhydrous aluminum chloride is 1:0.5-0.7:0.5-0.

8.

9. The high-strength, corrosion-resistant marine aluminum alloy plate according to claim 7, characterized in that: In the step B, the mass ratio of 1,5-naphthalenediamine, terephthalaldehyde and (2,4-xylyl)phenylphosphine oxide flame retardant is 2.3-2.7:1:3.4-4.

1.

10. A processing technology for a high-strength, corrosion-resistant marine aluminum alloy plate as claimed in any one of claims 1 to 9, characterized in that: The following steps are involved: S1. Weigh each element according to the weight percentage and put it into a smelting furnace. Set the temperature in the furnace to 750-800°C. After all the materials in the furnace are melted, stir them evenly for 30-45 minutes. After stirring, heat them to 850°C and keep them still for 10-20 minutes. Slag is removed and samples are taken for analysis. The alloy composition is tested and adjusted to obtain alloy materials. S2, refining the alloy material, the refining temperature is set to 700-730°C, the refining time is 20-25min, and after refining, it is left to stand for 15-20min, and then cast to obtain a slab, and then heat-treat it at 150-180°C for 4-8h to obtain an aluminum alloy slab; S3, hot rolling the aluminum alloy slab, heating it from 180 to 220° C. to 250 to 280° C., then keeping it warm for 5 to 7 hours, and then cold rolling it, with a feed temperature of 300 to 350° C. and a final rolling temperature of 220 to 250° C., cleaning and drying the slab after hot rolling and cold rolling to obtain an aluminum alloy substrate; S4, taking parts by weight of epoxy resin, modified curing agent, composite nanomaterial, curing agent, wetting agent, defoaming agent, leveling agent and dispersant into a high-speed disperser for stirring and dispersing, heating to 120-150° C. and evenly dispersing for 30-50 minutes, taking out the obtained anti-corrosion coating, and then evenly coating the anti-corrosion coating on the surface of the aluminum alloy substrate, drying and cooling, to obtain an anti-corrosion aluminum alloy plate; S5. Soak the anti-corrosion aluminum alloy plate in hydrogen peroxide in a deep freezer for 10 to 20 minutes. Take it out and keep it at -10°C for 20 to 30 minutes, then keep it at -40°C for 10 to 20 minutes, then keep it at -90°C for 30 to 40 minutes, then take it out of the deep freezer, place it in the air to naturally return to room temperature, and place it for 1 to 2 hours to obtain a high-strength and corrosion-resistant marine aluminum alloy plate.

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