Bio-based super-hydrophobic coating magnesium alloy material with anti-icing and corrosion-resistant functions as well as preparation method and application of bio-based super-hydrophobic coating magnesium alloy material

Abstract

The invention provides a bio-based super-hydrophobic coating magnesium alloy material with anti-icing and corrosion-resistant functions as well as a preparation method and application of the bio-based super-hydrophobic coating magnesium alloy material. According to the material, a polylipoic acid-metal ion-hydrophobic carbon black coating is constructed on the surface of the pretreated magnesium alloy, so that the key problems that the corrosion rate of the magnesium alloy is high and the surface of the magnesium alloy is easy to freeze in practical application are solved. The coating is firmly combined with a matrix through multiple hydrogen bond effects, and the coating is endowed with rapid self-repairing capability by virtue of synergistic dynamic effects of disulfide bonds, hydrogen bonds and metal coordinate bonds. And meanwhile, the doped hydrophobic carbon black particles obviously improve the surface super-hydrophobic performance. The self-repairing characteristic is combined with the super-hydrophobic structure, so that corrosion medium infiltration is effectively blocked, and the corrosion process of the magnesium alloy is greatly delayed. In addition, the coating has photo-thermal and electrothermal effects, active anti-icing and efficient deicing can be achieved, and the application potential of the magnesium alloy in a severe environment is remarkably expanded.

Description

Technical Field

[0001] This invention belongs to the field of magnesium alloy material surface treatment, specifically relating to a bio-based superhydrophobic coated magnesium alloy material with both anti-icing and corrosion-resistant functions, its preparation method, and its application. Background Technology

[0002] Magnesium alloys, as the lightest metallic structural materials, possess high specific strength, high specific stiffness, good electromagnetic shielding, and excellent casting and machinability, demonstrating enormous application potential in aerospace, transportation, electronic communications, and biomedical fields. However, the extremely high chemical reactivity of magnesium alloys results in very poor corrosion resistance, especially in harsh environments containing humid or chloride ions, where corrosion rates are extremely rapid. This severely restricts their engineering applications and service safety. Furthermore, in cold or high-humidity environments, magnesium alloy components are prone to icing and frosting, which can lead to mechanical failures, increased energy consumption, and safety hazards.

[0003] To improve the corrosion resistance of magnesium alloys, surface treatment technology has become a key approach. Current mainstream technologies, such as micro-arc oxidation (MAO), can grow a ceramic oxide layer in situ on the substrate surface, significantly improving corrosion and wear resistance. However, its microporous structure easily adsorbs corrosive media, and its hydrophilic surface cannot prevent ice crystal adhesion. Superhydrophobic coatings, by constructing micro-nano rough structures and low surface energy materials, can effectively block water and corrosive droplets from contacting the substrate. However, a single physical barrier is prone to failure after mechanical damage and lacks active anti-icing capabilities. Emerging self-healing coatings can restore some function after damage, but their repair efficiency, environmental adaptability, and bonding strength with the magnesium alloy substrate remain insufficient. Furthermore, existing anti-icing coatings are often complex in structure, expensive, or rely on non-renewable petrochemical raw materials, making it difficult to meet the requirements of sustainable development.

[0004] Therefore, developing a green coating that can firmly bond with magnesium alloy substrates, possess long-lasting self-healing capabilities to maintain protective performance, and integrate passive superhydrophobicity with active photoelectric / electrothermal de-icing functions is key to overcoming the bottleneck of magnesium alloy applications in harsh environments. Based on biomass-derived lipoic acid, whose molecules contain disulfide bonds and carboxyl groups, it can form a dynamic network through polymerization and coordination, providing an innovative approach to constructing an environmentally friendly smart coating with multiple protective functions. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides a bio-based superhydrophobic coated magnesium alloy material with both anti-icing and corrosion-resistant functions, its preparation method and application, and a schematic diagram of the preparation process is shown below. Figure 1 As shown, the main purpose is to solve the problems of rapid corrosion rate and easy surface icing faced by current magnesium alloy materials in harsh environments.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A method for preparing a magnesium alloy material with a bio-based superhydrophobic coating that combines anti-icing and corrosion resistance functions includes the following steps: (1) Take magnesium alloy material, use sandpaper to polish it until the surface is flat and smooth, clean it, dry it and set it aside; (2) The magnesium alloy material from step (1) is subjected to micro-arc oxidation treatment to obtain a magnesium alloy material with a porous ceramic oxide layer on the surface. (3) After heating the thioctic acid powder to melt into a liquid at 130~160℃, add the metal ion salt and stir at 130~160℃ until a homogeneous polythioctic acid-metal ion complex is formed (generally stir for 5~20 minutes), and set aside. (4) Use silane coupling agent to modify carbon black particles hydrophobically to obtain hydrophobic carbon black nanoparticles, disperse them in ethanol to form a hydrophobic carbon black nanoparticle dispersion, add the hydrophobic carbon black nanoparticle dispersion to the polythioctic acid-metal ion complex in step (3), stir at 130~160℃ until uniformly dispersed to obtain composite coating liquid. (5) Apply the composite coating liquid from step (4) to the surface of the magnesium alloy material from step (2) and cool it to room temperature to obtain the magnesium alloy material with the bio-based superhydrophobic coating that has both anti-icing and corrosion-resistant functions.

[0007] Preferably, the magnesium alloy material mentioned in step (1) is a magnesium alloy of grade AZ31B, AZ91D or WE43.

[0008] Preferably, the electrolyte used in the micro-arc oxidation treatment in step (2) is a silicate-based or phosphate-based aqueous solution. The specific process is as follows: Then, the pretreated magnesium alloy material is placed in the electrolyte as the anode, and stainless steel is used as the counter electrode. Micro-arc oxidation is performed in constant voltage mode for 2~5 minutes, that is, a porous micro-arc oxidation layer is obtained on the magnesium alloy. The electrolyte composition is: 6~15g / L Na2SiO3, 2~8g / L KF and 5~10g / L NaOH, and the solvent is water. In constant voltage mode, the control voltage is 200~400V, the frequency is 300~1000Hz, and the duty cycle is 1~5%.

[0009] Preferably, the molar ratio of thioctic acid to metal ions in step (3) is (50~10000):1.

[0010] Preferably, the metal ion mentioned in step (3) is at least one of iron ion, copper ion, zinc ion or calcium ion. The metal ion salt is a soluble salt of the metal ion, such as a chloride of iron ion, copper ion, zinc ion or calcium ion.

[0011] Preferably, in step (4), the silane coupling agent is octadecyltrimethoxysilane, hexadecyltrimethoxysilane, tetradecyltrimethoxysilane or dodecyltrimethoxysilane.

[0012] Preferably, in step (4), carbon black particles and silane coupling agent are dispersed in ethanol at a ratio of 1g:(1~2)mL, with a mass-to-volume ratio of carbon black particles to ethanol of (1~3)g:(50~150)mL. The mixture is ultrasonically treated for 10~30 minutes, stirred at room temperature for 12~36 hours, centrifuged or filtered, and the solid is dried to obtain hydrophobic carbon black nanoparticles. Preferably, in step (4), during the preparation of the hydrophobic carbon black nanoparticles: the particle size of the carbon black particles is 10~80nm; the ultrasonic power is 50~100W; and the ultrasonic frequency is 30~50kHz. Drying refers to drying at 40℃~80℃.

[0013] Preferably, the mass ratio of thioctic acid to hydrophobic carbon black nanoparticles in step (4) is 3:(0.1~1.0), and the mass-volume ratio of hydrophobic carbon black nanoparticles to ethanol is (0.1~1.0) g:(5~15) mL.

[0014] Preferably, the coating method described in step (5) is dip coating or spin coating. When dip coating, the dip coating time is 3s to 1min and the dip coating temperature is 130 to 160℃.

[0015] Preferably, the drying in steps (1) and (2) refers to drying at 40℃~80℃ for 10~60 min.

[0016] The magnesium alloy material prepared by the above method has a bio-based superhydrophobic coating with both anti-icing and corrosion-resistant functions.

[0017] The above-mentioned magnesium alloy materials with bio-based superhydrophobic coatings that combine anti-icing and corrosion resistance are used in the manufacture of aerospace components, marine engineering equipment, or cryogenic outdoor equipment components.

[0018] The technical benefits of the above-mentioned solution are a clear process route, controllable operation, and suitability for large-scale preparation. The developed polythioctic acid-metal ion@hydrophobic carbon black composite coating adheres tightly to the micro-arc oxidation pretreatment layer based on intermolecular forces such as hydrogen bonds. The dynamic disulfide bonds, hydrogen bonds, and metal coordination bonds of polythioctic acid in this coating synergistically endow it with rapid self-healing capabilities, effectively repairing minor damage. The doped hydrophobic nanoparticles stably construct a superhydrophobic surface and efficiently absorb light energy, converting it into heat energy. The self-healing properties ensure long-term corrosion protection, while the superhydrophobicity and photothermal / electrothermal effects synergistically achieve efficient passive anti-icing and active de-icing. This coating system significantly slows down the corrosion rate of magnesium alloys and improves their anti-icing capability, providing a sustainable solution for expanding the reliable application of magnesium alloys in harsh environments. Attached Figure Description

[0019] Figure 1 A schematic diagram of the fabrication process for preparing bio-based superhydrophobic coated magnesium alloy materials with both anti-icing and corrosion-resistant functions. Figure 2 SEM images and elemental distribution diagrams of the micro-arc oxidation coating obtained in the second step of Example 1 and the polythiooctanoic acid-iron@hydrophobic carbon black-1 composite coating obtained in the third step. Figure 3 The static water contact angles of the magnesium alloy obtained in the first step of Example 1, the micro-arc oxidation coating obtained in the second step, and the polythiooctanoic acid-iron@hydrophobic carbon black-1 composite coating obtained in the third step; Figure 4 The potentiodynamic polarization curves are for the magnesium alloy obtained in the first step of Example 1, the micro-arc oxidation coating obtained in the second step, and the polythiooctanoic acid-iron@hydrophobic carbon black-1 composite coating obtained in the third step. Figure 5 The freezing time of the magnesium alloy in the first step of Example 1, the micro-arc oxidation coating obtained in the second step, the polythiooctanoic acid-iron@hydrophobic carbon black-1 composite coating obtained in the third step, and the polythiooctanoic acid-iron coating. Figure 6 This is an optical image of the surface ice droplet melting process of the polythiooctanoic acid-iron@hydrophobic carbon black-1 composite coating prepared in the third step of Example 1 under sunlight. Figure 7 This is an optical image of the surface ice droplet melting process of the polythiooctanoic acid-iron@hydrophobic carbon black-1 composite coating prepared in the third step of Example 1 under a voltage of 10 volts; Figure 8 Cross-sectional image and corresponding elemental distribution diagram of polythiooctanoic acid-iron@hydrophobic carbon black-1 coating; Figure 9 SEM images and corresponding elemental distributions of the self-healing process of the polythiooctanoic acid-iron@hydrophobic carbon black-0.1 composite coating obtained in the third step of Example 2; Figure 10 This is an optical image of the surface of an AZ31B magnesium alloy sample pretreated with pure hydrophobic carbon black particles in Example 2. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to examples, but the scope of protection of the present invention is not limited thereto.

[0021] All magnesium alloy materials used in this invention can be purchased through commercial channels.

[0022] Example 1: A method for preparing a bio-based superhydrophobic coated magnesium alloy material with both anti-icing and corrosion-resistant functions includes the following steps: Step 1: Pretreatment of magnesium alloy matrix Cut the AZ31B magnesium alloy sheet to the required size (2 cm × 2 cm × 0.5 cm), and polish it successively with 400 grit, 800 grit, and 1500 grit sandpaper until the surface is smooth. Then, ultrasonically clean it for 10 minutes each with deionized water and anhydrous ethanol to remove surface contaminants and grease. Finally, dry it in a 60°C oven for 30 minutes for later use.

[0023] Step 2: Micro-arc oxidation treatment of magnesium alloy surface The pretreated AZ31B magnesium alloy sample was used as the anode, and stainless steel as the counter electrode, placed in an electrolytic cell containing a silicate-based electrolyte (500 mL; 8 g / L sodium hydroxide, 10 g / L sodium silicate, 5 g / L potassium fluoride, with water as the solvent). Using commercial micro-arc oxidation equipment, the sample was treated for 3 min at 300 V, 4% duty cycle, and 500 Hz under AC power conditions, forming a porous ceramic oxide layer in situ on the sample surface. After treatment, the sample was removed, thoroughly rinsed with deionized water, and dried at 60℃ for 30 min to obtain a magnesium alloy substrate with a micro-arc oxide layer on the surface, ready for use.

[0024] Step 3: Preparation of hydrophobic carbon black nanoparticles Weigh 2.0 g of carbon black particles (30–50 nm) and 3.0 mL of hexadecyltrimethoxysilane, and disperse them in 100 mL of anhydrous ethanol. Sonicate the mixture (60 W, 42 kHz) for 15 min, then stir continuously at room temperature for 24 h to obtain a homogeneous black suspension. Separate the solid product by centrifugation or filtration, and dry to constant weight in a vacuum oven at 60 °C to obtain silane-modified superhydrophobic carbon black nanoparticles.

[0025] Step 4: Preparation of polythiooctanoic acid-iron@hydrophobic carbon black-1 composite coating liquid Weigh 3.0 g of thioctic acid powder and place it in a reaction vessel. Heat the mixture to 150°C in an oil bath and stir continuously until the thioctic acid is completely melted to form a yellow, transparent liquid. Weigh ferric chloride (FeCl3) according to a ferric chloride to thioctic acid molar ratio of 1:80 and dissolve it in 5 mL of anhydrous ethanol to form a clear yellow solution. Slowly add the above iron salt ethanol solution dropwise to the molten thioctic acid liquid and stir continuously at 150°C for 10 min to form a homogeneous polythioctic acid-iron polymer solution.

[0026] Weigh 1.0 g of the superhydrophobic carbon black nanoparticles prepared in step three, and adjust the mass ratio of superhydrophobic carbon black nanoparticles to thioctic acid to 1:3 (i.e., superhydrophobic carbon black nanoparticles: thioctic acid). Disperse the nanoparticles in 10 mL of anhydrous ethanol and sonicate (60 W, 42 kHz) for 10 min to form a uniform dispersion. Then, add the carbon black dispersion to the above polythioctic acid-iron polymer solution and mechanically stir continuously at 150 °C until the carbon black particles are uniformly dispersed, obtaining a black, uniform polythioctic acid-iron@hydrophobic carbon black-1 composite coating liquid.

[0027] Step 5: Applying the composite coating Using a dip-coating method, the AZ31B magnesium alloy sample pretreated with micro-arc oxidation in the second step was immersed in a composite coating solution maintained at 150°C, held for 5 seconds, and then pulled out at a constant speed. The coated sample was then cooled at room temperature. Subsequently, a magnesium alloy material with a polythiooctanoic acid-iron@hydrophobic carbon black-1 composite coating was obtained.

[0028] Preparation of polythioctic acid-iron coating: The AZ31B magnesium alloy sample pretreated by micro-arc oxidation in the second step was immersed in a polythioctic acid-iron polymer solution maintained at 150°C, held for 5 seconds, and then pulled out at a constant speed. The coated sample was then cooled at room temperature. Subsequently, a magnesium alloy material with a polythioctic acid-iron coating on its surface was obtained.

[0029] Magnesium alloy samples modified with polythiooctanoic acid-iron@hydrophobic carbon black-1 composite coating and polythiooctanoic acid-iron coating were placed in sample bags and sealed for later use.

[0030] The AZ31B magnesium alloy pretreated with micro-arc oxidation and its surface-modified polythiooctanoic acid-iron@hydrophobic carbon black-1 composite coating samples prepared in Example 1 were systematically characterized, including scanning electron microscopy (SEM) observation, energy dispersive spectroscopy (EDS) analysis, static water contact angle testing, potentiodynamic polarization curve testing, surface icing delay testing, photothermal de-icing testing, electrothermal de-icing testing, and cross-sectional image testing. The experimental results are as follows: Figures 2 to 8 As shown.

[0031] Figure 2 The images show the SEM morphology and EDS elemental distribution of each sample. The samples underwent gold sputtering before observation. Numerous irregular micropores (approximately 0.3-3 μm in diameter) were observed on the surface of the micro-arc oxidation coating, resulting from gas evolution and thermal stress during the treatment process, which may serve as channels for corrosive media penetration. After coating with a polythiooctanoic acid-iron@hydrophobic carbon black-1 composite coating, the surface morphology transformed into a volcano-like structure composed of microspheres. EDS analysis indicated that this structure mainly contained S, C, Si, and O elements, with trace amounts of Fe, consistent with the chemical composition of the composite coating.

[0032] Figure 3 The results show the static water contact angle of each sample. The contact angle of the untreated AZ31B substrate was 75.9°. After micro-arc oxidation, due to the hydrophilicity and porous structure of MgO, the contact angle decreased to 35.1°, exhibiting a hydrophilic surface. After coating with a composite coating, a hierarchical micro-nano structure was formed on the surface, and the contact angle increased significantly to 164.5°, demonstrating excellent superhydrophobic properties.

[0033] The corrosion resistance of the coating was evaluated using a CS2350M electrochemical workstation (Wuhan Kosite) via potentiodynamic polarization curves. A three-electrode system was employed: the working electrode was the sample (exposed area 1 cm²). 2 The counter electrode was a platinum sheet, the reference electrode was a saturated calomel electrode (SCE), and the electrolyte was a 3.5 wt.% NaCl solution (room temperature). After the open circuit potential stabilized, the test was performed at a scan rate of 1 mV / s. The corrosion potential was obtained by Tafel extrapolation. E corr ) and corrosion current density ( i corr ).like Figure 4 As shown, the composite coating significantly reduces the corrosion current: AZ31B substrate i corr 2.80 × 10 -4 A•cm 2 The micro-arc oxidation coating reduced to 4.02 × 10⁻⁶. -7 A•cm 2 The composite coating further reduced the density to 1.29 × 10⁻⁶. -9 A•cm 2 This excellent corrosion resistance stems from the dense composite barrier formed by the superhydrophobic layer and the underlying micro-arc oxide layer.

[0034] Place the sample on a cold stage at -15℃, add 50-100 μL of deionized water to its surface, and observe and record the freezing process. Figure 5 As shown, the freezing times of the AZ31B substrate and the micro-arc oxidation layer surface were 210 s and 230 s, respectively, exhibiting poor anti-icing performance. In contrast, the freezing time of water droplets on the composite coating surface was significantly extended to 480 s, mainly due to its micro-nano hierarchical structure effectively trapping air and reducing the solid-liquid contact area, thereby inhibiting ice nucleation. The freezing time of the polythioctic acid-iron coating was 300 s, and the surface water droplets did not exhibit a hydrophobic state, indicating that the coating without hydrophobic carbon black particles does not possess significant anti-icing capability.

[0035] The photothermal de-icing capability of the coating was evaluated at 0 °C. The sample was placed on a cold stage at -15 °C and 75% relative humidity. After a droplet (approximately 100 μL) added to the coating surface completely froze, the melting process of the ice droplet under simulated sunlight was recorded. Figure 6 As shown, the ice droplets completely melted within 240 s, and the melting began at the ice-coating interface and progressed upwards. This rapid melting was due to the photothermal conversion effect of the carbon black in the coating, which absorbed light energy and rapidly increased the interface temperature, thus promoting the melting of the ice layer.

[0036] Although solar thermal de-icing is environmentally friendly, its sustainability and efficiency depend on lighting conditions, making it unsuitable for low-light environments or scenarios requiring rapid de-icing. Therefore, the performance of electrothermal de-icing was further evaluated. Figure 7 As shown, at a voltage of 10 V, ice droplets (approximately 100 μL) on the surface of the composite coating transform from solid to transparent spherical water droplets within 90 s, demonstrating highly efficient electrothermal de-icing capability.

[0037] Cross-sectional images of the prepared polythiooctanoic acid-iron@hydrophobic carbon black-1 coating are shown below. Figure 8 As shown, cross-sectional imaging reveals that the thickness of the micro-arc oxidation layer on the magnesium alloy surface is approximately 8 μm, exhibiting a porous and loose structure containing cracks and through-holes. After preparing polythiooctanoic acid-iron@hydrophobic carbon black-1, a polymer layer approximately 60 μm thick covers the micro-arc oxidation surface, effectively penetrating and sealing the pores (red circle), a conclusion also drawn from the corresponding S, C, and O elemental distribution diagrams.

[0038] Example 2: A method for preparing a bio-based superhydrophobic coated magnesium alloy material with both anti-icing and corrosion-resistant functions includes the following steps: Step 1: Pretreatment of magnesium alloy matrix Cut the AZ31B magnesium alloy sheet to the required size (2 cm × 2 cm × 0.5 cm), and polish it successively with 400 grit, 800 grit, and 1500 grit sandpaper until the surface is smooth. Then, ultrasonically clean it for 10 minutes each with deionized water and anhydrous ethanol to remove surface contaminants and grease. Finally, dry it in a 60°C oven for 30 minutes for later use.

[0039] Step 2: Micro-arc oxidation treatment of magnesium alloy surface The pretreated AZ31B magnesium alloy sample was used as the anode, and stainless steel as the counter electrode, placed in an electrolytic cell containing a silicate-based electrolyte (500 mL; 8 g / L sodium hydroxide, 10 g / L sodium silicate, 5 g / L potassium fluoride, with water as the solvent). Using commercial micro-arc oxidation equipment, the sample was treated for 3 min at 300 V, 4% duty cycle, and 500 Hz under AC power conditions, forming a porous ceramic oxide layer in situ on the sample surface. After treatment, the sample was removed, thoroughly rinsed with deionized water, and dried at 60℃ for 30 min to obtain a magnesium alloy substrate with a micro-arc oxide layer on the surface, ready for use.

[0040] Step 3: Preparation of hydrophobic carbon black nanoparticles Weigh 2.0 g of carbon black particles and 3.0 mL of hexadecyltrimethoxysilane, and disperse them in 100 mL of anhydrous ethanol. Sonicate the mixture for 10 min, then stir continuously at room temperature for 24 h to obtain a uniform black suspension. Separate the solid product by centrifugation or filtration, and dry it to constant weight in a vacuum oven at 60 °C to obtain silane-modified superhydrophobic carbon black nanoparticles.

[0041] Step 4: Preparation of polythiooctanoic acid-iron@hydrophobic carbon black-0.1 composite coating liquid Weigh 3.0 g of thioctic acid powder and place it in a reaction vessel. Heat the mixture to 150°C in an oil bath and stir continuously until the thioctic acid is completely melted to form a yellow, transparent liquid. Weigh ferric chloride (FeCl3) according to a ferric chloride to thioctic acid molar ratio of 1:80 and dissolve it in 5 mL of anhydrous ethanol to form a clear yellow solution. Slowly add the above iron salt ethanol solution dropwise to the molten thioctic acid liquid and stir continuously at 150°C for 10 min to form a polythioctic acid-iron polymer solution.

[0042] Weigh 0.1 g of the superhydrophobic carbon black nanoparticles prepared in step three, and adjust the mass ratio of these nanoparticles to thioctic acid to 0.1:3 (i.e., silane-modified superhydrophobic carbon black nanoparticles: thioctic acid). Disperse the nanoparticles in 10 mL of anhydrous ethanol and sonicate for 10 min to form a uniform dispersion. Then, add the carbon black dispersion to the above-prepared polythioctic acid-iron polymer solution and mechanically stir continuously at 150 °C for 10 min until the carbon black particles are uniformly dispersed, obtaining a black, uniform polythioctic acid-iron@hydrophobic carbon black-0.1 composite coating solution.

[0043] Step 5: Applying the composite coating Using a dip-coating method, the AZ31B magnesium alloy sample pretreated with micro-arc oxidation in the second step was immersed in a composite coating solution maintained at 150°C, held for 5 seconds, and then pulled out at a constant speed. The coated sample was then cooled at room temperature. Subsequently, a magnesium alloy material with a polythiooctanoic acid-iron@hydrophobic carbon black-0.1 composite coating was obtained.

[0044] Preparation of pure hydrophobic carbon black particle coating: 0.1 g of the superhydrophobic carbon black nanoparticles prepared in step 3 was weighed and dispersed in 10 mL of anhydrous ethanol. The mixture was ultrasonically treated for 10 min to form a uniform dispersion. Subsequently, the 10 mL carbon black dispersion was dropped onto a 2 cm × 2 cm surface of the sample and dried at 60 °C to constant weight to obtain a pure hydrophobic carbon black particle coating. Optical photographs are shown below. Figure 10 As shown.

[0045] The magnesium alloy sample modified with polythiooctanoic acid-iron@hydrophobic carbon black-0.1 composite coating was placed in a sample bag and sealed for later use.

[0046] The self-healing performance of the AZ31B magnesium alloy pretreated by micro-arc oxidation prepared in Example 2 and its surface-modified polythiooctanoic acid-iron@hydrophobic carbon black-0.1 composite coating samples was tested, and the results are as follows: Figure 9 As shown.

[0047] The repair status was observed and the details of the self-repair process were analyzed using scanning electron microscopy (SEM). For example... Figure 9 As shown, in the initial stage, a scratch with a width of approximately 200 μm was artificially created on the coating surface. Energy dispersive spectroscopy (EDS) analysis indicated that this area mainly contained C, O, and Si elements. After 12 h of repair at room temperature, the damaged area showed obvious signs of repair. After 24 h of repair, the scratch was completely healed, and its composition was refilled with C, O, and S elements, indicating that the polythiooctanoic acid-iron@hydrophobic carbon black-0.1 composite coating achieved complete repair, confirming that the coating has excellent self-healing ability. In contrast, pure hydrophobic carbon black particles could not form a film on the surface of the AZ31B magnesium alloy sample pretreated with micro-arc oxidation. Figure 10 (As shown), and it does not have self-healing capabilities. The above description is only a partial embodiment of the present invention. For those skilled in the art, several improvements and substitutions can be made without departing from the principle of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a bio-based superhydrophobic coated magnesium alloy material with both anti-icing and corrosion-resistant functions, characterized in that, The process is as follows: (1) The surface of the magnesium alloy material is pretreated by grinding, cleaning and drying; (2) Perform micro-arc oxidation treatment on the magnesium alloy material after the pretreatment in step (1) to form a porous micro-arc oxidation layer on its surface; (3) After heating thioctic acid to 130~160℃ to melt it, add metal ion salt and stir at 130~160℃ to form a homogeneous polythioctic acid-metal ion complex. (4) Prepare hydrophobic carbon black nanoparticles modified with silane coupling agent, disperse them in ethanol to form a hydrophobic carbon black nanoparticle dispersion, add the hydrophobic carbon black nanoparticle dispersion to the polythioctic acid-metal ion complex in step (3), stir at 130~160℃ until uniformly dispersed, and obtain the composite coating liquid. (5) The composite coating liquid obtained in step (4) is coated onto the surface of the magnesium alloy substrate with porous micro-arc oxide layer obtained in step (2), and cooled to room temperature to obtain the bio-based superhydrophobic coated magnesium alloy material.

2. The preparation method according to claim 1, characterized in that, The magnesium alloy material mentioned in step (1) is a magnesium alloy of grade AZ31B, AZ91D or WE43.

3. The preparation method according to claim 1, characterized in that, The electrolyte used in the micro-arc oxidation process in step (2) is a silicate system electrolyte or a phosphate system electrolyte.

4. The preparation method according to claim 1, characterized in that, In step (3), the molar ratio of lipoic acid to metal ions is 50:1 to 10000:1; the metal ion is Fe. 3+ Cu 2+ Zn 2+ and Ca 2+ At least one of the following, wherein the metal ion salt is a soluble salt of the metal ion.

5. The preparation method according to claim 1, characterized in that, The silane coupling agent in step (4) is selected from at least one of octadecyltrimethoxysilane, hexadecyltrimethoxysilane, tetradecyltrimethoxysilane and dodecyltrimethoxysilane.

6. The preparation method according to claim 1 or 5, characterized in that, In step (4), the preparation process of hydrophobic carbon black nanoparticles is as follows: carbon black particles and silane coupling agent are dispersed in ethanol at a ratio of 1g:(1~2)mL, ultrasonically treated for 10~30 minutes, stirred at room temperature for 12~36 hours, centrifuged or filtered, and the solid is dried to obtain hydrophobic carbon black nanoparticles.

7. The preparation method according to claim 1, characterized in that, The mass ratio of thioctic acid to hydrophobic carbon black nanoparticles in step (4) is 3:(0.1~1.0), and the mass-volume ratio of hydrophobic carbon black nanoparticles to ethanol is (0.1~1.0) g:(5~15) mL.

8. The preparation method according to claim 1, characterized in that, The coating method described in step (5) is dip coating or spin coating.

9. A bio-based superhydrophobic coated magnesium alloy material with anti-icing and corrosion-resistant functions, prepared by any one of claims 1 to 8.

10. The application of a bio-based superhydrophobic coated magnesium alloy material as described in claim 9 in aerospace, marine engineering, or cryogenic outdoor equipment components.

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