A multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy and its preparation method

Abstract

This invention discloses a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy and its preparation method, belonging to the technical field of magnesium alloys. The multifunctional biomimetic self-healing smooth surface on the magnesium-lithium alloy has a water contact angle of 110–140° and a sliding angle of 3–8°, and also exhibits excellent anti-fouling, self-cleaning, self-healing, impact resistance, durability, and corrosion resistance (corrosion rate of 0.005–0.09 mmpy). The preparation method includes an anodizing stage, a hydrothermal treatment stage, a chemical modification stage, and a lubricant injection stage. This invention, through the aforementioned preparation method, ensures the excellent corrosion resistance of the magnesium-lithium alloy while rapidly exhibiting excellent self-healing effects when subjected to external impacts or scratches, thereby improving the durability of the magnesium-lithium alloy. This is crucial for expanding the demand for high-performance lightweight materials in engineering applications.

Description

Technical Field

[0001] This invention belongs to the technical field of magnesium alloys, and relates to a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy and its preparation method. Background Technology

[0002] Light metals and their alloys hold great promise for sustainable development, necessitating enhanced energy conservation and further cost reductions in equipment. Magnesium-lithium alloys are considered the lightest structural metals currently available, attracting widespread attention in military, aerospace, biomedical, and 3C product fields due to their low density, high specific strength and stiffness, and ease of machining. However, because Mg (Mg = Mg...)... 2+ +2e E θ =-2.37) and Li (Li=Li + +e,E θ The high chemical reactivity of components such as Mg (-3.05V) and the significant potential difference between Mg and Li result in extremely poor corrosion resistance of magnesium-lithium alloys to external corrosive environments. With the widespread application of magnesium-lithium alloys across various industries, corrosion prevention has become a crucial task. Unlike conventional metals such as steel and copper, magnesium-lithium alloys lack surface protection, making them prone to rapid, temporary breakdown, which can lead to malfunctions in advanced systems or facilities. Considering that water is an indispensable participant in metal corrosion, enhancing the durability of magnesium-lithium alloys by applying coatings or increasing surface water resistance is a practical approach.

[0003] Nature is a source of inspiration for functional surfaces. Inspired by lotus leaves, artificial superhydrophobic surfaces have become the best candidates for metal protection due to their excellent water repellency (Ouyang Y, Chen Z, Guo E, et al. Bioinspired superhydrophobic surface via one-step electrodeposition and its corrosion inhibition for Mg-Li alloy[J], Colloids and Surfaces A: Physicochemical and Engineering Aspects, 648, 2022: 129145–129156.). Superhydrophobic surfaces (SHS) with a water contact angle greater than 150° and a slip angle less than 10° can usually be obtained by combining a rough surface microstructure with a low surface energy material. Such surfaces can trap air into a specific structure to form an air barrier, thereby protecting the substrate from the effects of external liquids. However, due to thermodynamic and hydrodynamic effects, the air barrier obtained by SHS is metastable and cannot withstand high-pressure environments and the intrusion of low-surface-energy organic liquids. On the other hand, SHS has low mechanical strength and is easily damaged by external physical impacts and scratches, which leads to a decrease in its hydrophobicity and loss of additional protective barrier (Long Y, Yin X, Mu P, et al. Slippery liquid-infused porous surface (SLIPS) with superior liquid repellency, anti-corrosion, anti-icing and intensified durability for protecting substrates[J], Chemical Engineering Journal, 401, 2020: 126137–126143). Therefore, it is urgent to develop effective alternatives to overcome the problems faced by SHS.

[0004] Nature once again inspires people to find effective solutions. Inspired by pitcher plants, Aizenberg et al. constructed a liquid-repellent surface, called Smooth Liquid-Injected Porous Surface (SLIPS), by filling the surface of micro-nano porous substrates with lubricant (Wong T, Kang S, Aizenberg J, et al, Bioinspired self-repairing slipperysurfaces with pressure-stable omniphobicity[J], Nature, 477, 2011, 443–447). Due to the injection of lubricant, the gas barrier layer of SHS is replaced by a liquid barrier layer. Given that gas is more compressible than liquid, the gas barrier layer of SHS cannot withstand the high-pressure and harsh external environment as effectively as the lubricating layer of SLIPS. In addition, SLIPS has a self-healing property that SHS does not possess. When the SLIPS surface is damaged, it can spontaneously restore its structural integrity by utilizing the inherent fluidity of the lubricant. Therefore, SLIPS obtained through liquid injection technology is more stable than the metastable SHS and has a better effect on protecting the substrate from corrosion.

[0005] The development of SLIPS should meet three criteria: 1) the lubricant must adhere stably to the substrate; 2) the lubricant must have a stronger ability to wet the substrate than the repelled liquid; and 3) the lubricant and the repelled liquid must be immiscible. For example, Zhang et al. prepared SLIPS with hydrophobic and anticorrosion properties by coating a steel plate surface with an epoxy resin (ER) coating as a substrate, then using a template method to prepare textured ER, and subsequently injecting modified mineral oil onto the textured ER (Zhang M, Chen P, Wang G, et al, Preparation of bio-inspired liquid-infused surface on epoxy resin coating for reliable hydrophobic and anticorrosion properties, Progress in Organic Coatings, 184, 2023: 107851–107863.). Zhu et al. obtained SLIPS with antifouling and self-cleaning effects by spraying multiple layers of hydrophobic polyelectrolyte onto a circular stainless steel surface and impregnating it with a lubricant (Zhu G, Cho S, Zhang H, et al. Slippery liquid-infused porous surfaces (SLIPS) using layer-by-layer polyelectrolyte assembly in organic solvent, Langmuir, 34, 2018: 4722–4731.). Sakuraba et al. formed a porous structure on an aluminum substrate using anodizing technology, and then obtained a corrosion-resistant SLIPS coating with self-healing function after impregnation with a low surface energy lubricant (Sakuraba K, Kitano S, Kowalski D, et al., Slippery liquid infused porous surfaces on aluminum for corrosion protection with improved self-healing ability, ACS Applied Materials & Interfaces, 13, 2021: 45089–45096.). While the methods described above have yielded SLIPS, they still face drawbacks such as weak adhesion to the substrate, complex and time-consuming coating preparation, and numerous pores on the coating surface. Therefore, ensuring both the self-healing function of SLIPS and strong adhesion and durability of the coating to the substrate remains a significant challenge.

[0006] In summary, addressing the bottleneck issue hindering the engineering application of magnesium-lithium alloys—poor corrosion resistance—and developing smooth surfaces with intelligent, multifunctional, biomimetic, and self-healing properties are key areas of focus to overcome the shortcomings of existing technologies. Summary of the Invention

[0007] To address the shortcomings and drawbacks of the aforementioned technologies, the present invention aims to provide a multifunctional biomimetic self-healing smooth surface on magnesium-lithium alloys and its preparation method. By combining processes such as anodic oxidation and hydrothermal in-situ growth of layered hydroxide (LDH), chemical modification, and lubricant injection, a multifunctional biomimetic self-healing smooth surface (SLIPS) with high adhesion, self-healing, self-cleaning, anti-fouling, durability, and corrosion resistance is obtained.

[0008] This invention provides a method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy, the method comprising the following steps:

[0009] S1, Anodizing Stage

[0010] (1) Prepare a mixed electrolyte by mixing silicates, strong bases, weak acids, and organic salts;

[0011] (2) The magnesium-lithium alloy substrate is used as the anode and the stainless steel sheet is used as the cathode. The substrate is placed in the electrolyte obtained in step (1) and anodized at room temperature using a DC power supply.

[0012] (3) The anodized sample prepared in step (2) is ultrasonically cleaned with anhydrous ethanol solution and then dried in air to obtain a sample with an anodized coating;

[0013] S2, Hydrothermal Treatment Stage

[0014] (1) The sample with anodized coating prepared in step S1 is transferred to a high-pressure reactor with a polytetrafluoroethylene liner and deionized water is added to generate water vapor.

[0015] (2) Place the high-pressure reactor in an electric heating oven and heat it to 100-200°C. Keep it at that temperature for 0.5-24 hours, then remove the high-pressure reactor and let it cool naturally in the air.

[0016] (3) The hydrothermally treated sample prepared in step (2) is ultrasonically cleaned and dried in anhydrous ethanol to obtain a sample coated with layered hydroxide;

[0017] S3, Chemical Modification Stage

[0018] The sample coated with layered hydroxide prepared in step S2 was placed in an anhydrous ethanol solution containing perfluorodecyltriethoxysilane for 0.5 to 24 hours and then removed. It was then dried in an oven at a temperature of 50 to 200°C to obtain a sample with a superhydrophobic coating.

[0019] S4, Lubricant Injection Stage

[0020] (1) Apply the lubricant to the sample surface with the superhydrophobic coating obtained in step S3 using a pipette;

[0021] (2) Place the sample in a vacuum container and evacuate to remove excess air;

[0022] (3) After taking out the sample, place it at an angle of 1 to 90° for 1 to 24 hours to remove excess lubricant and obtain a multifunctional biomimetic self-healing smooth surface on the magnesium-lithium alloy.

[0023] Preferably, in step S1, the silicate is sodium silicate or one or more of its hydrated compounds, and the concentration of the silicate is 20-50 g / L;

[0024] Preferably, in step S1, the strong base is one or more of sodium hydroxide, potassium hydroxide, or their hydrated compounds, and the concentration of the strong base is 10-30 g / L.

[0025] Preferably, the weak acid in step S1 is one or more of oxalic acid, acetic acid, and citric acid, and the concentration of the weak acid is 5-20 g / L.

[0026] Preferably, the organic salt in step S1 is one or more of sodium oxalate, sodium ethylenediaminetetraacetate, sodium citrate, sodium acetate, or their aqueous compounds, and the concentration of the organic salt is 5-20 g / L.

[0027] Preferably, the DC power supply in step S1 is an A-BF programmable linear DC power supply with a current density of 0.5–2 A·cm. -2 The anodizing time is 10–30 min;

[0028] Preferably, the volume of the polytetrafluoroethylene liner in step S2 is 25-200 mL;

[0029] Preferably, the volume of deionized water added in step S2 is 10-50 mL;

[0030] Preferably, the concentration of the anhydrous ethanol solution containing perfluorodecyltriethoxysilane in step S3 is 0.1–0.5 mol / L;

[0031] Preferably, the drying time in the oven in step S3 is 0.5 to 5 hours;

[0032] Preferably, the volume of lubricant in step S4 is 10–1000 μL;

[0033] Preferably, in step S4, the vacuum container is a vacuum drying oven with a vacuum degree of 10. -3 Below Pa;

[0034] Preferably, the multifunctional biomimetic self-healing smooth surface on the magnesium-lithium alloy in step S4 has a water contact angle of 110-140° and a sliding angle of 3-8°, and also has excellent anti-fouling, self-cleaning, self-healing, impact resistance, durability and corrosion resistance (corrosion rate of 0.005-0.09 mmpy).

[0035] Compared with the prior art, the present invention has the following advantages:

[0036] This invention draws inspiration from nature to create a novel biomimetic non-wetting, robust, and durable surface with intelligent reversibility, which has great potential in the field of metal corrosion and protection.

[0037] This invention prepares a smooth liquid-injected porous surface (SLIPS) on a magnesium-lithium alloy surface using a combination of in-situ growth and chemical modification, solving the problems of poor adhesion between the coating and the substrate, cumbersome preparation process, and high surface porosity of current coatings. The layered hydroxide prepared by in-situ growth in this invention not only seals anodic oxidation defects but also provides a stable and robust structure for fluorosilane chemical modification and lubricant injection. Furthermore, the SLIPS prepared by this invention is also suitable for protecting other materials, meeting the needs of many emerging fields such as biomedical fluid handling, antifouling, and self-cleaning windows.

[0038] The multifunctional biomimetic self-healing smooth surface on the magnesium-lithium alloy described in this invention has a water contact angle of 110–140° and a sliding angle of 3–8°, and also exhibits excellent anti-fouling, self-cleaning, self-healing, impact resistance, durability, and corrosion resistance. The SLIPS in this invention demonstrates outstanding corrosion resistance, with a corrosion rate of 0.005–0.09 mmpy.

[0039] The method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy according to this invention combines in-situ growth and chemical modification. The resulting SLIPS exhibits strong adhesion to the substrate, providing a multifunctional protective barrier for the magnesium-lithium alloy. This multifunctional biomimetic self-healing smooth surface on the magnesium-lithium alloy not only overcomes the shortcomings of current superhydrophobic coatings (SHS), but also cleverly reverses superhydrophobicity and smoothness as needed, thereby enhancing the corrosion resistance of the magnesium-lithium alloy and opening up possibilities for its wider practical applications.

[0040] In summary, this invention employs a combination of in-situ growth, chemical modification, and lubricant injection, overcoming the shortcomings of existing methods. This method offers advantages such as low cost, high efficiency, stable performance, and wide applicability. While ensuring the excellent corrosion resistance of the magnesium-lithium alloy, it rapidly exhibits superior self-healing properties upon external impact or scratches, thereby enhancing the alloy's durability. This is crucial for expanding the demand for high-performance, lightweight materials in engineering applications. Attached Figure Description

[0041] Figure 1 This is a surface morphology diagram of the multifunctional biomimetic self-healing smooth surface on the magnesium-lithium alloy of Embodiment 1 of the present invention;

[0042] Figure 2 This is a diagram showing the water contact angle and sliding angle of the multifunctional biomimetic self-healing smooth surface on the magnesium-lithium alloy in Embodiment 1 of the present invention.

[0043] Figure 3 This is a diagram illustrating the self-cleaning effect of the multifunctional biomimetic self-healing smooth surface on the magnesium-lithium alloy in Embodiment 1 of the present invention.

[0044] Figure 4 This is a test diagram of the corrosion resistance of the multifunctional biomimetic self-healing smooth surface on the magnesium-lithium alloy of Embodiment 1 of the present invention. Detailed Implementation

[0045] The present invention will be further described below with reference to specific embodiments. It should be noted that the described embodiments are only some embodiments of the present invention and are not a limitation of the present invention. The scope of protection of the present invention is not limited to the following embodiments.

[0046] Example 1

[0047] A method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy, the method comprising the following steps:

[0048] S1, Anodizing Stage

[0049] (1) Prepare a mixed electrolyte by mixing 40 g / L sodium silicate, 25 g / L sodium hydroxide, 10 g / L oxalic acid, 5 g / L sodium oxalate and 5 g / L sodium ethylenediaminetetraacetate.

[0050] (2) Using a magnesium-lithium alloy substrate as the anode and a stainless steel sheet as the cathode, place them in the electrolyte obtained in step (1) and apply a current density of 1 A·cm⁻¹. -2 The A-BF programmable linear DC power supply was anodized at room temperature for 15 minutes.

[0051] (3) The anodized sample prepared in step (2) is ultrasonically cleaned with anhydrous ethanol solution and then dried in air to obtain a sample with an anodized coating;

[0052] S2, Hydrothermal Treatment Stage

[0053] (1) The sample with anodized coating prepared in step S1 is transferred to a high-pressure reactor with a polytetrafluoroethylene liner of 50 mL, and 20 mL of deionized water is added to generate water vapor.

[0054] (2) Place the high-pressure reactor in an electric heating oven and heat it to 130°C. After keeping it at that temperature for 10 hours, remove the high-pressure reactor and let it cool naturally in the air.

[0055] (3) The hydrothermally treated sample prepared in step (2) is ultrasonically cleaned and dried in anhydrous ethanol to obtain a sample coated with layered hydroxide;

[0056] S3, Chemical Modification Stage

[0057] The sample coated with layered hydroxide prepared in step S2 was placed in anhydrous ethanol solution containing 0.2 mol / L perfluorodecyltriethoxysilane for 2 hours and then removed. It was then dried in an oven at 100°C for 2 hours to obtain a sample with a superhydrophobic coating.

[0058] S4, Lubricant Injection Stage

[0059] (1) Apply 30 μL of lubricant to the surface of the sample with superhydrophobic coating obtained in step S3 using a pipette;

[0060] (2) Place the sample in a vacuum drying oven and evacuate to a vacuum level of 10. -3 Below Pa, to remove excess air;

[0061] (3) After taking out the sample, place it at a 60° tilt angle for 5 hours to remove excess lubricant and obtain a sample containing a multifunctional biomimetic self-healing smooth surface (SLIPS).

[0062] The surface morphology of the multifunctional biomimetic self-healing smooth surface on the magnesium-lithium alloy is shown in the figure below. Figure 1 As shown, the surface is dense and uniform, with visible micro- and nano-structures. The multifunctional biomimetic self-healing smooth surface prepared in this embodiment has a water contact angle of 122° and a sliding angle of 6°. Figure 2 As shown. The self-cleaning effect of the multifunctional biomimetic self-healing smooth surface prepared in this embodiment is as follows. Figure 3As shown, water droplets carry away contaminants from the coating surface until no contaminants remain, indicating that the coating has self-cleaning and anti-fouling effects. The corrosion resistance test of the multifunctional biomimetic self-healing smooth surface prepared in this embodiment is as follows: Figure 4 As shown in the figure, the prepared multifunctional biomimetic self-healing smooth surface exhibits excellent corrosion resistance with a corrosion rate of 0.075 mmpy.

[0063] Example 2

[0064] A method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy, the method comprising the following steps:

[0065] S1, Anodizing Stage

[0066] (1) Prepare a mixed electrolyte by mixing 50 g / L sodium silicate, 30 g / L sodium hydroxide, 8 g / L oxalic acid, 5 g / L sodium oxalate and 5 g / L sodium ethylenediaminetetraacetate.

[0067] (2) Using a magnesium-lithium alloy substrate as the anode and a stainless steel sheet as the cathode, the mixture is placed in the electrolyte obtained in step (1) and subjected to a current density of 1.5 A·cm⁻¹. -2 The A-BF programmable linear DC power supply was anodized at room temperature for 10 minutes.

[0068] (3) The anodized sample prepared in step (2) is ultrasonically cleaned with anhydrous ethanol solution and then dried in air to obtain a sample with an anodized coating;

[0069] S2, Hydrothermal Treatment Stage

[0070] (1) The sample with anodized coating prepared in step S1 is transferred to a high-pressure reactor with a polytetrafluoroethylene liner of 25 mL and 10 mL of deionized water is added to generate water vapor.

[0071] (2) Place the high-pressure reactor in an electric heating oven and heat it to 150°C. After keeping it at that temperature for 5 hours, remove the high-pressure reactor and let it cool naturally in the air.

[0072] (3) The hydrothermally treated sample prepared in step (2) is ultrasonically cleaned and dried in anhydrous ethanol to obtain a sample coated with layered hydroxide;

[0073] S3, Chemical Modification Stage

[0074] The sample coated with layered hydroxide prepared in step S2 was placed in an anhydrous ethanol solution containing 0.5 mol / L perfluorodecyltriethoxysilane for 5 hours and then removed. It was then dried in an oven at 50°C for 5 hours to obtain a sample with a superhydrophobic coating.

[0075] S4, Lubricant Injection Stage

[0076] (1) Apply 50 μL of lubricant to the surface of the sample with superhydrophobic coating obtained in step S3 using a pipette;

[0077] (2) Place the sample in a vacuum drying oven and evacuate to a vacuum level of 10. -3 Below Pa, to remove excess air;

[0078] (3) After taking out the sample, place it at a 30° tilt angle for 24 hours to remove excess lubricant and obtain a sample containing a multifunctional biomimetic self-healing smooth surface (SLIPS).

[0079] The multifunctional biomimetic self-healing smooth surface prepared in this embodiment has a water contact angle of 140° and a sliding angle of 4°, and also exhibits excellent antifouling, self-cleaning, self-healing, impact resistance, durability, and corrosion resistance. The multifunctional biomimetic self-healing smooth surface prepared in this embodiment demonstrates outstanding corrosion resistance, with a corrosion rate of 0.05 mmpy.

[0080] Example 3

[0081] A method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy, the method comprising the following steps:

[0082] S1, Anodizing Stage

[0083] (1) Prepare a mixed electrolyte by mixing 20 g / L sodium silicate, 10 g / L sodium hydroxide, 5 g / L oxalic acid, 5 g / L sodium oxalate and 5 g / L sodium ethylenediaminetetraacetate.

[0084] (2) Using a magnesium-lithium alloy substrate as the anode and a stainless steel sheet as the cathode, place them in the electrolyte obtained in step (1) and apply a current density of 2 A·cm⁻¹. -2 The A-BF programmable linear DC power supply was anodized at room temperature for 30 minutes.

[0085] (3) The anodized sample prepared in step (2) is ultrasonically cleaned with anhydrous ethanol solution and then dried in air to obtain a sample with an anodized coating;

[0086] S2, Hydrothermal Treatment Stage

[0087] (1) The sample with anodized coating prepared in step S1 is transferred to a high-pressure reactor with a polytetrafluoroethylene liner of 200 mL, and 50 mL of deionized water is added to generate water vapor.

[0088] (2) Place the high-pressure reactor in an electric heating oven and heat it to 120°C. After keeping it warm for 24 hours, remove the high-pressure reactor and let it cool naturally in the air.

[0089] (3) The hydrothermally treated sample prepared in step (2) is ultrasonically cleaned and dried in anhydrous ethanol to obtain a sample coated with layered hydroxide;

[0090] S3, Chemical Modification Stage

[0091] The sample coated with layered hydroxide prepared in step S2 was placed in anhydrous ethanol solution containing 0.4 mol / L perfluorodecyltriethoxysilane for 10 h and then removed. It was then dried in an oven at 100 °C for 3 h to obtain a sample with a superhydrophobic coating.

[0092] S4, Lubricant Injection Stage

[0093] (1) Apply 100 μL of lubricant to the surface of the sample with superhydrophobic coating obtained in step S3 using a pipette;

[0094] (2) Place the sample in a vacuum drying oven and evacuate to a vacuum level of 10. -3 Below Pa, to remove excess air;

[0095] (3) After taking out the sample, place it at a 90° tilt angle for 5 hours to remove excess lubricant and obtain a sample containing a multifunctional biomimetic self-healing smooth surface (SLIPS).

[0096] The multifunctional biomimetic self-healing smooth surface prepared in this embodiment has a water contact angle of 110° and a sliding angle of 8°, and also exhibits excellent antifouling, self-cleaning, self-healing, impact resistance, durability, and corrosion resistance. The multifunctional biomimetic self-healing smooth surface prepared in this embodiment demonstrates outstanding corrosion resistance, with a corrosion rate of 0.02 mmpy.

[0097] Example 4

[0098] A method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy, the method comprising the following steps:

[0099] S1, Anodizing Stage

[0100] (1) Prepare a mixed electrolyte by mixing 45 g / L sodium silicate, 28 g / L sodium hydroxide, 8 g / L oxalic acid, 8 g / L sodium oxalate and 8 g / L sodium ethylenediaminetetraacetate.

[0101] (2) Using a magnesium-lithium alloy substrate as the anode and a stainless steel sheet as the cathode, the mixture is placed in the electrolyte obtained in step (1) and subjected to a current density of 1.4 A·cm⁻¹. -2The A-BF programmable linear DC power supply was anodized at room temperature for 20 minutes.

[0102] (3) The anodized sample prepared in step (2) is ultrasonically cleaned with anhydrous ethanol solution and then dried in air to obtain a sample with an anodized coating;

[0103] S2, Hydrothermal Treatment Stage

[0104] (1) The sample with anodized coating prepared in step S1 is transferred to a high-pressure reactor with a polytetrafluoroethylene liner of 100 mL, and 30 mL of deionized water is added to generate water vapor.

[0105] (2) Place the high-pressure reactor in an electric heating oven and heat it to 140°C. After keeping it at that temperature for 12 hours, remove the high-pressure reactor and let it cool naturally in the air.

[0106] (3) The hydrothermally treated sample prepared in step (2) is ultrasonically cleaned and dried in anhydrous ethanol to obtain a sample coated with layered hydroxide;

[0107] S3, Chemical Modification Stage

[0108] The sample coated with layered hydroxide prepared in step S2 was placed in anhydrous ethanol solution containing 0.3 mol / L perfluorodecyltriethoxysilane for 3 hours, then removed and dried in an oven at 80°C for 1 hour to obtain a sample with a superhydrophobic coating.

[0109] S4, Lubricant Injection Stage

[0110] (1) Apply 20 μL of lubricant to the surface of the sample with superhydrophobic coating obtained in step S3 using a pipette;

[0111] (2) Place the sample in a vacuum drying oven and evacuate to a vacuum level of 10. -3 Below Pa, to remove excess air;

[0112] (3) After taking out the sample, place it at a 70° tilt angle for 3 hours to remove excess lubricant and obtain a sample containing a multifunctional biomimetic self-healing smooth surface (SLIPS).

[0113] The multifunctional biomimetic self-healing smooth surface prepared in this embodiment has a water contact angle of 130° and a sliding angle of 7°, and also exhibits excellent antifouling, self-cleaning, self-healing, impact resistance, durability, and corrosion resistance. The multifunctional biomimetic self-healing smooth surface prepared in this embodiment demonstrates outstanding corrosion resistance, with a corrosion rate of 0.03 mmpy.

[0114] Example 5

[0115] A method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy, the method comprising the following steps:

[0116] S1, Anodizing Stage

[0117] (1) Prepare a mixed electrolyte by mixing 25 g / L sodium silicate, 15 g / L sodium hydroxide, 10 g / L oxalic acid, 15 g / L sodium oxalate and 10 g / L sodium ethylenediaminetetraacetate.

[0118] (2) Using a magnesium-lithium alloy substrate as the anode and a stainless steel sheet as the cathode, the mixture is placed in the electrolyte obtained in step (1) and subjected to a current density of 1.3 A·cm⁻¹. -2 The A-BF programmable linear DC power supply was anodized at room temperature for 15 minutes.

[0119] (3) The anodized sample prepared in step (2) is ultrasonically cleaned with anhydrous ethanol solution and then dried in air to obtain a sample with an anodized coating;

[0120] S2, Hydrothermal Treatment Stage

[0121] (1) The sample with anodized coating prepared in step S1 is transferred to a high-pressure reactor with a polytetrafluoroethylene liner of 125 mL, and 40 mL of deionized water is added to generate water vapor.

[0122] (2) Place the high-pressure reactor in an electric heating oven and heat it to 155°C. After keeping it at that temperature for 3 hours, remove the high-pressure reactor and let it cool naturally in the air.

[0123] (3) The hydrothermally treated sample prepared in step (2) is ultrasonically cleaned and dried in anhydrous ethanol to obtain a sample coated with layered hydroxide;

[0124] S3, Chemical Modification Stage

[0125] The sample coated with layered hydroxide prepared in step S2 was placed in anhydrous ethanol solution containing 0.2 mol / L perfluorodecyltriethoxysilane for 2 hours and then removed. It was then dried in an oven at 85°C for 1 hour to obtain a sample with a superhydrophobic coating.

[0126] S4, Lubricant Injection Stage

[0127] (1) Apply 15 μL of lubricant to the surface of the sample with superhydrophobic coating obtained in step S3 using a pipette;

[0128] (2) Place the sample in a vacuum drying oven and evacuate to a vacuum level of 10. -3 Below Pa, to remove excess air;

[0129] (3) After taking out the sample, place it at an 80° tilt angle for 2 hours to remove excess lubricant and obtain a sample containing a multifunctional biomimetic self-healing smooth surface (SLIPS).

[0130] The multifunctional biomimetic self-healing smooth surface prepared in this embodiment has a water contact angle of 125° and a sliding angle of 6°, and also exhibits excellent antifouling, self-cleaning, self-healing, impact resistance, durability, and corrosion resistance. The multifunctional biomimetic self-healing smooth surface prepared in this embodiment demonstrates outstanding corrosion resistance, with a corrosion rate of 0.08 mmpy.

[0131] In the above-mentioned solution, the present invention draws inspiration from nature to create a novel biomimetic non-wetting, robust and durable surface with intelligent reversibility, which has great potential in the field of metal corrosion and protection.

[0132] This invention prepares a smooth liquid-injected porous surface (SLIPS) on a magnesium-lithium alloy surface using a combination of in-situ growth and chemical modification, solving the problems of poor adhesion between the coating and the substrate, cumbersome preparation process, and high surface porosity of current coatings. The layered hydroxide prepared by in-situ growth in this invention not only seals anodic oxidation defects but also provides a stable and robust structure for fluorosilane chemical modification and lubricant injection. Furthermore, the SLIPS prepared by this invention is also suitable for protecting other materials, meeting the needs of many emerging fields such as biomedical fluid handling, antifouling, and self-cleaning windows.

[0133] The multifunctional biomimetic self-healing smooth surface on the magnesium-lithium alloy described in this invention has a water contact angle of 110–140° and a sliding angle of 3–8°, and also exhibits excellent anti-fouling, self-cleaning, self-healing, impact resistance, durability, and corrosion resistance. The SLIPS in this invention demonstrates outstanding corrosion resistance, with a corrosion rate of 0.005–0.09 mmpy.

[0134] The method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy according to this invention combines in-situ growth and chemical modification. The resulting SLIPS exhibits strong adhesion to the substrate, providing a multifunctional protective barrier for the magnesium-lithium alloy. This multifunctional biomimetic self-healing smooth surface on the magnesium-lithium alloy not only overcomes the shortcomings of current superhydrophobic coatings (SHS), but also cleverly reverses superhydrophobicity and smoothness as needed, thereby enhancing the corrosion resistance of the magnesium-lithium alloy and opening up possibilities for its wider practical applications.

[0135] In summary, this invention employs a combination of in-situ growth, chemical modification, and lubricant injection, overcoming the shortcomings of existing methods. This method offers advantages such as low cost, high efficiency, stable performance, and wide applicability. While ensuring the excellent corrosion resistance of the magnesium-lithium alloy, it rapidly exhibits superior self-healing properties upon external impact or scratches, thereby enhancing the alloy's durability. This is crucial for expanding the demand for high-performance, lightweight materials in engineering applications.

[0136] The above description represents the preferred embodiments of the present invention. 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 method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy, characterized in that, The preparation method includes the following steps: S1, Anodizing Stage (1) Prepare a mixed electrolyte by mixing silicates, strong bases, weak acids, and organic salts; (2) The magnesium-lithium alloy substrate is used as the anode and the stainless steel sheet is used as the cathode. The substrate is placed in the electrolyte obtained in step (1) and anodized at room temperature using a DC power supply. (3) The anodized sample prepared in step (2) is ultrasonically cleaned with anhydrous ethanol solution and then dried in air to obtain a sample with an anodized coating; S2, Hydrothermal Treatment Stage (1) The sample with anodized coating prepared in step S1 is transferred to a high-pressure reactor with a polytetrafluoroethylene liner and deionized water is added to generate water vapor. (2) Place the high-pressure reactor in an oven and heat it to 100-200°C. Keep it at that temperature for 0.5-24 hours. Then, remove the high-pressure reactor and allow it to cool naturally in the air. (3) The hydrothermally treated sample prepared in step (2) is ultrasonically cleaned and dried in anhydrous ethanol to obtain a sample coated with layered hydroxide; S3, Chemical Modification Stage The sample coated with layered hydroxide prepared in step S2 was placed in an anhydrous ethanol solution containing perfluorodecyltriethoxysilane for 0.5 to 24 hours and then removed. It was then dried in an oven at a temperature of 50 to 200°C to obtain a sample with a superhydrophobic coating. S4, Lubricant Injection Stage (1) Apply the lubricant to the sample surface with the superhydrophobic coating obtained in step S3 using a pipette; (2) Place the sample in a vacuum container and evacuate to remove excess air; (3) After taking out the sample, place it at an angle of 1 to 90° for 1 to 24 hours to remove excess lubricant and obtain a sample with a multifunctional biomimetic self-healing smooth surface. In step S1, the silicate is sodium silicate or one or more of its hydrated compounds, and the concentration of the silicate is 20–50 g / L; the strong base in step S1 is sodium hydroxide, potassium hydroxide or one or more of its hydrated compounds, and the concentration of the strong base is 10–30 g / L; the weak acid in step S1 is oxalic acid, acetic acid, citric acid or one or more, and the concentration of the weak acid is 5–20 g / L; the organic salt in step S1 is sodium oxalate, sodium ethylenediaminetetraacetate, sodium citrate, sodium acetate or one or more of its hydrated compounds, and the concentration of the organic salt is 5–20 g / L; the DC power supply in step S1 is an A-BF programmable linear DC power supply with a current density of 0.5–2 A·cm⁻¹. -2 The anodizing time is 10-30 min; the concentration of the anhydrous ethanol solution containing perfluorodecyltriethoxysilane in step S3 is 0.1-0.5 mol / L.

2. The method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy according to claim 1, characterized in that, In step S2, the volume of the polytetrafluoroethylene liner is 25-200 mL.

3. The method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy according to claim 1, characterized in that, The volume of deionized water added in step S2 is 10-50 mL.

4. The method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy according to claim 1, characterized in that, The drying time in the oven in step S3 is 0.5 to 5 hours.

5. The method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy according to claim 1, characterized in that, In step S4, the volume of lubricant is 10–1000 μL.

6. The method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy according to claim 1, characterized in that, In step S4, the vacuum container is a vacuum drying oven with a vacuum level of 10. -3 Below Pa.

7. A method for preparing a multifunctional biomimetic self-healing smooth surface on a magnesium-lithium alloy according to any one of claims 1 to 6, characterized in that, In step S4, the water contact angle of the multifunctional biomimetic self-healing smooth surface on the magnesium-lithium alloy is 110–140°, the sliding angle is 3–8°, and the corrosion rate is 0.005–0.09 mmpy.

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