Durable super-hydrophobic titanium alloy surface and preparation method thereof

Abstract

The invention relates to a durable super-hydrophobic titanium alloy surface and a preparation method thereof, and belongs to the technical field of super-hydrophobic materials. The preparation method of the durable super-hydrophobic titanium alloy surface comprises the following steps that the surface of a titanium alloy matrix is pretreated, and a high-activity multi-site micro-nano coarse structure is formed; the low-surface-energy substance and the pretreated titanium alloy matrix are placed in a closed space, the low-surface-energy substance is heated and evaporated into gaseous molecules, and the heating temperature is lower than the boiling point; the gaseous molecules are deposited and adsorbed on the surface of the micro-nano rough structure of the titanium alloy matrix; and after adsorption is completed, the low-surface-energy molecules on the titanium alloy surface and a titanium alloy matrix are subjected to a chemical bonding reaction, a super-hydrophobic coating is formed, and the durable super-hydrophobic titanium alloy surface is obtained. The process is simple, and the obtained super-hydrophobic titanium alloy surface can still keep the super-hydrophobic performance for a long time in severe environments such as mechanical friction, acid and alkali corrosion and salt mist and has excellent mechanical durability and chemical stability.

Description

Technical Field

[0001] This invention relates to a durable superhydrophobic titanium alloy surface and its preparation method, belonging to the field of superhydrophobic materials technology. Background Technology

[0002] Superhydrophobic surfaces are typically defined as surfaces with a water contact angle greater than 150° and a roll-off angle less than 10°. Their unique non-wetting properties offer broad application prospects in self-cleaning, corrosion prevention, and anti-icing. Constructing superhydrophobic structures on metallic surfaces is considered an effective means of mitigating metal corrosion. However, superhydrophobic metallic surfaces prepared using traditional methods often suffer from insufficient durability: on the one hand, the organic modification layers used to reduce surface energy are often attached via immersion or electrodeposition, resulting in weak adhesion to the substrate. They are easily damaged and detached under mechanical forces such as friction and scratching, leading to rapid loss of hydrophobicity; on the other hand, the organic modification layers may degrade in chemical environments such as strong acids, strong alkalis, or salt spray, causing decreased chemical stability and preventing long-term maintenance of superhydrophobic properties. Therefore, improving the mechanical durability and chemical stability of superhydrophobic surfaces is a key issue that urgently needs to be addressed in the field of superhydrophobic materials.

[0003] To address the aforementioned issues, some improvements have been attempted in existing technologies. For example, some studies have explored constructing special micro / nano structures (such as micrometer-scale "nest" structures) on metal surfaces to store and protect low surface energy materials, thereby improving the stability of superhydrophobic surfaces. Another approach involves using vapor deposition to modify rough surfaces with low surface energy molecules, allowing organic molecules to chemically bond to the metal, thus enhancing the bonding strength. However, these methods still suffer from drawbacks such as complex processes, high costs, difficulty in large-area fabrication, insufficient film density and uniformity, or inadequate acid and alkali resistance. Therefore, developing a new method that is simple, low-cost, and can significantly improve the durability of superhydrophobic surfaces is of great significance. Summary of the Invention

[0004] The first objective of this invention is to provide a method for preparing a durable superhydrophobic titanium alloy surface.

[0005] To achieve the first objective of this invention, the method for preparing the durable superhydrophobic titanium alloy surface includes the following steps:

[0006] (a) The surface of the titanium alloy substrate is pretreated to form a highly active multi-site micro-nano rough structure;

[0007] (b) A titanium alloy substrate with m grams of low surface energy material and a surface area of ​​S square centimeters, after pretreatment in step (a), is placed in a sealed space with a volume of V liters. The low surface energy material is heated and evaporated into gaseous molecules at a temperature below the boiling point. The titanium alloy substrate after pretreatment in step (a) comes into contact with the gaseous molecules, which are deposited and adsorbed onto the micro / nano rough structure surface of the titanium alloy substrate. The m / V / S ratio is 0.034 g / L / cm². 2 ~1.279g / L / cm 2 ;

[0008] (c) After adsorption is complete, the low surface energy molecules on the titanium alloy surface undergo a chemical bonding reaction with the titanium alloy matrix to form a superhydrophobic coating, thus obtaining a durable superhydrophobic titanium alloy surface.

[0009] In one specific embodiment, the pretreatment in step (a) includes at least one of mechanical roughening, chemical etching, electrochemical etching, anodic oxidation, micro-arc oxidation, or hydrothermal alkaline treatment.

[0010] Pretreatment is performed to construct micro / nano-scale porous or fibrous network structures on the titanium alloy surface. The highly active multi-site micro / nano rough structure described in step (a) has a high specific surface area and abundant surface active functional groups such as hydroxyl groups and oxides, providing a large number of adsorption active sites for low surface energy molecules.

[0011] In one specific embodiment, the preprocessing includes:

[0012] Prepare the electrolyte by mixing a 0.2–0.3 mol / L ethylene glycol solution of choline chloride with hydrogen peroxide at a volume ratio of 50:2.5–3.5.

[0013] A titanium alloy substrate was used as the anode and graphite as the cathode, with a distance of 1.5 to 2 cm between them. They were placed together in an electrolyte and energized at 55 to 65 V for 10 to 15 minutes at room temperature. The anode was then removed, cleaned, and dried to prepare a rough porous structure.

[0014] In one specific embodiment, the low surface energy material in step (b) is selected from at least one of fatty acids, siloxanes, or fluorosilanes; preferably at least one of siloxanes or fluorosilanes; more preferably at least one of polydimethylsiloxane emulsion or 1H,1H,2H,2H-perfluorodecyltrimethoxysilane.

[0015] When the low surface energy substance is a fatty acid, m / V / S = 0.426 g / L / cm 2 ~1.279g / L / cm 2 ;

[0016] When the low surface energy material is a siloxane, m / V / S = 0.213 g / L / cm 2 ~0.639g / L / cm 2 ;

[0017] When the low surface energy material is a fluorosilane, m / V / S = 0.034 g / L / cm 2 ~0.068g / L / cm 2 .

[0018] In one specific embodiment, the heating in step (b) is performed by resistance heating, and the temperature of the resistance heating is controlled above the melting point and below the boiling point of the low surface energy material.

[0019] In one specific embodiment, the contact described in step (b) is carried out in a closed container, where a titanium alloy substrate is placed with a low surface energy material spaced 3-5 cm apart and heated to allow gaseous molecules to undergo saturated adsorption on the surface of the titanium alloy substrate.

[0020] In one specific embodiment, the chemical bonding reaction described in step (c) is carried out under heating conditions, so that the functional groups of low surface energy molecules react with the active groups on the surface of the titanium alloy to form chemical bonds, thereby firmly bonding to the matrix in the form of chemical bonds.

[0021] In one specific embodiment, the low surface energy substance is a fatty acid, and the heating conditions in step (c) are to heat to 100-150°C, hold for 30-90 min, and cool to room temperature; the heating rate is preferably 10°C / min.

[0022] In one specific embodiment, the low surface energy material is a siloxane or a fluorosilane, and the heating conditions in step (c) are to raise the temperature to 180-220°C, hold it at that temperature for 30-90 minutes, and then cool it to room temperature.

[0023] The preparation process of this invention is carried out under normal pressure and without inert gas protection, without the participation of organic solvents or subsequent curing treatment.

[0024] The second objective of this invention is to provide a durable superhydrophobic titanium alloy surface.

[0025] To achieve the second objective of this invention, the durable superhydrophobic titanium alloy surface is prepared using the method described above;

[0026] The durable superhydrophobic titanium alloy surface has a micro-nano rough structure and a low surface energy organic coating. The low surface energy molecules in the organic coating are chemically bonded to the micro-nano rough structure surface of the titanium alloy. The water contact angle of the durable superhydrophobic titanium alloy surface is greater than 150°.

[0027] Preferably, the surface of the durable superhydrophobic titanium alloy is peeled off with tape 100 times, and the surface water contact angle is greater than 145°.

[0028] The durable superhydrophobic titanium alloy has a linear friction distance of 2000cm and a water contact angle of over 140°.

[0029] The durable superhydrophobic titanium alloy surface, when immersed for 240 hours under conditions of pH=2 or pH=12, has a surface water contact angle of 135° or higher, preferably 140° or higher.

[0030] More preferably, after the durable superhydrophobic titanium alloy surface is impacted with water for 60 minutes, the contact angle is above 148°.

[0031] The low surface energy organic coating has a thickness of nanometers, uniformly covers the surface of the titanium alloy micro-nano structure, and fills some of the pores, thereby improving the surface's mechanical strength and chemical stability.

[0032] Beneficial effects

[0033] This invention overcomes the shortcomings of existing technologies and provides a durable superhydrophobic titanium alloy surface and its preparation method. This method combines low-temperature evaporation technology with surface-enhanced adsorption to construct a molecularly ordered, high-bonding-density superhydrophobic coating on the titanium alloy surface, significantly improving the surface's mechanical durability and chemical stability. Specific advantages include:

[0034] 1. Simple process and mild conditions: The entire process is carried out under normal pressure, without the need for a vacuum environment or inert gas protection; heating is achieved using conventional resistance heating, with temperatures below the boiling point of the substances, eliminating the need for high-energy methods such as high-temperature plasma or electron beams. The operation is solvent-free and requires no complex post-processing, making the process simple and controllable.

[0035] 2. Ordered Molecular Arrangement and High Bonding Density: Due to the numerous active sites pre-existing on the titanium alloy surface, gaseous low-surface-energy molecules can arrange themselves in an orderly manner during deposition and adsorption, forming a uniform and dense organic film. Simultaneously, under heating conditions below the boiling point of the substance, the main chemical components and structure of the low-energy material are preserved, and the molecules undergo sufficient chemical bonding reactions with the substrate, significantly increasing the interfacial bonding density. This high bonding density and orderly arranged molecular film ensures a strong bond between the superhydrophobic coating and the substrate, making it difficult to detach.

[0036] 3. Excellent Durability: The superhydrophobic titanium alloy surface prepared by this invention exhibits excellent stability under harsh conditions such as mechanical friction, acid and alkali corrosion, and salt spray. The organic coating is firmly attached to the substrate through chemical bonds, and the micro-nano structure provides support and protection for the coating, making it less prone to losing its superhydrophobicity during friction and wear. Simultaneously, the dense molecular film and chemical bonds effectively block the erosion of chemical media, maintaining superhydrophobic properties even after long-term immersion in acid, alkali, and salt environments.

[0037] 4. Broad Application Prospects: The preparation process of this invention is low-cost and highly repeatable, making it suitable for large-area fabrication. The resulting durable superhydrophobic titanium alloy surface has broad application prospects and practical value in fields such as metal corrosion prevention, marine antifouling, self-cleaning coatings, and anti-icing and drag reduction. Attached Figure Description

[0038] Figure 1 The images show the scanning electron microscope (SEM) microstructure and water contact angle of the superhydrophobic titanium alloy surfaces prepared in Examples 1-3 of this invention. Figure 1 In the diagram, (a), (b), and (c) correspond to the adsorption of fatty acids, siloxanes, and fluorosilanes, respectively.

[0039] Figure 2 The image shows the contact angle of the superhydrophobic surface prepared in Example 1 under water impact testing.

[0040] Figure 3 The image shows the contact angle of the superhydrophobic surface prepared in Example 1 under acidic environment testing.

[0041] Figure 4 The image shows the contact angle of the superhydrophobic surface prepared in Example 2 under water impact testing.

[0042] Figure 5 The image shows the contact angle of the superhydrophobic surface prepared in Example 2 under acidic environment testing.

[0043] Figure 6 The image shows the contact angle of the superhydrophobic surface prepared in Example 2 under alkaline environment testing.

[0044] Figure 7 The image shows the contact angle of the superhydrophobic surface prepared in Example 3 under water impact testing.

[0045] Figure 8 The image shows the contact angle of the superhydrophobic surface prepared in Example 3 under acidic environment testing.

[0046] Figure 9 The image shows the contact angle of the superhydrophobic surface prepared in Example 3 under alkaline environment testing.

[0047] Figure 10This is a process flow diagram and schematic diagram of a specific embodiment of the present invention.

[0048] Figure 11 The images show a comparison of the peeling of superhydrophobic surface tapes prepared in Example 1 and Comparative Example 2.

[0049] Figure 12 Linear friction comparison of superhydrophobic surfaces prepared in Example 1 and Comparative Example 2.

[0050] Figure 13 Comparison of the water impact resistance of the superhydrophobic surfaces prepared in Example 1 and Comparative Example 2.

[0051] Figure 14 Comparison of acid immersion resistance of superhydrophobic surfaces prepared in Example 1 and Comparative Example 2.

[0052] Figure 15 The contact angle diagram of the superhydrophobic surface prepared in Example 2 after linear friction for 1200 cm is shown.

[0053] Figure 16 The images show a comparison of the peeling of the superhydrophobic surface tapes prepared in Example 3 and Comparative Example 3.

[0054] Figure 17 The image shows a comparison of the linear friction of the superhydrophobic surfaces prepared in Example 3 and Comparative Example 3.

[0055] Figure 18 The image shows a comparison of the water impact resistance of the superhydrophobic surfaces prepared in Example 3 and Comparative Example 3.

[0056] Figure 19 The image shows a comparison of the acid and alkali resistance of the superhydrophobic surfaces prepared in Example 3 and Comparative Example 3.

[0057] Figure 20 Comparison of the superhydrophobic surfaces prepared in Example 1, Comparative Example 2, Example 3 and Comparative Example 3 after 96h salt spray test.

[0058] Figure 21 The image shows the water contact angle of the superhydrophobic surface prepared in Example 3 after a 30-day salt spray test. Detailed Implementation

[0059] To achieve the first objective of this invention, the method for preparing the durable superhydrophobic titanium alloy surface includes the following steps:

[0060] (a) The surface of the titanium alloy substrate is pretreated to form a highly active multi-site micro-nano rough structure;

[0061] (b) A titanium alloy substrate with m grams of low surface energy material and a surface area of ​​S square centimeters, after pretreatment in step (a), is placed in a sealed space with a volume of V liters. The low surface energy material is heated and evaporated into gaseous molecules at a temperature below the boiling point. The titanium alloy substrate after pretreatment in step (a) comes into contact with the gaseous molecules, which are deposited and adsorbed onto the micro / nano rough structure surface of the titanium alloy substrate. The m / V / S ratio is 0.034 g / L / cm². 2 ~1.279g / L / cm 2 ;

[0062] (c) After adsorption is complete, the low surface energy molecules on the titanium alloy surface undergo a chemical bonding reaction with the titanium alloy matrix to form a superhydrophobic coating, thus obtaining a durable superhydrophobic titanium alloy surface.

[0063] like Figure 10 As shown, (a) step pretreatment of the titanium alloy surface: The titanium alloy substrate is surface-treated to form a highly active multi-site micro / nano rough structure. This structure has a high specific surface area and a rich surface chemical environment, with dense adsorption active sites and a large number of active functional groups such as hydroxyl (-OH) and oxide (Me-O) on the surface, thus endowing it with excellent adsorption performance. This micro / nano rough structure can be a porous structure, a fiber network structure, or other patterned morphology, but its core feature is the high density of surface active sites and functional groups, which facilitates the subsequent adsorption and bonding of low surface energy molecules.

[0064] (b) Low-temperature evaporation of low-surface-energy substances: Low-surface-energy organic substances are used as source materials and heated to an appropriate temperature. The heating temperature is controlled above the melting point and below the boiling point of the substance, so that it evaporates into gaseous molecules, while avoiding decomposition or cracking, thereby maintaining the original composition and structure of the molecules basically unchanged.

[0065] Deposition and adsorption of gaseous molecules: Under normal pressure, a pretreated titanium alloy sample is brought into contact with low surface energy gaseous molecules generated by evaporation. Preferably, in a closed container, the titanium alloy sample is placed at a certain distance from a solid or liquid low surface energy material and heated, allowing the gaseous molecules to fill the container and undergo saturated adsorption on the sample surface. Due to the strong adsorption properties of the micro-nano structure on the titanium alloy surface, the gaseous molecules are first physically adsorbed onto the rough surface and, under the influence of surface tension and active sites, arrange themselves in an orderly manner to form a uniform and dense molecular adsorption layer.

[0066] (c) Step-by-step chemical bonding and superhydrophobic coating formation: Maintaining the heating conditions for a period of time allows the low surface energy molecules adsorbed on the titanium alloy surface to react chemically with the active groups on the substrate surface, forming chemical bonds. For example, the carboxyl groups of fatty acid molecules can undergo esterification with the hydroxyl groups on the titanium alloy surface, and the alkoxy groups of siloxanes or fluorosilanes can hydrolyze and condense with the hydroxyl groups on the titanium surface to form Ti-O-Si bonds, etc. Through chemical bonding, low surface energy molecules are firmly fixed to the titanium alloy surface in a chemically bonded manner, forming a superhydrophobic organic coating with ordered molecules and high bonding density. After the reaction is complete, the furnace is cooled to room temperature to obtain a durable superhydrophobic titanium alloy surface. Both chemical durability and mechanical durability are improved.

[0067] In one specific embodiment, the pretreatment in step (a) includes at least one of mechanical roughening, chemical etching, electrochemical etching, anodic oxidation, micro-arc oxidation, or hydrothermal alkaline treatment.

[0068] Pretreatment is performed to construct micro / nano-scale porous or fibrous network structures on the titanium alloy surface. The highly active multi-site micro / nano rough structure described in step (a) has a high specific surface area and abundant surface active functional groups such as hydroxyl groups and oxides, providing a large number of adsorption active sites for low surface energy molecules.

[0069] In one specific embodiment, the preprocessing includes:

[0070] Prepare the electrolyte by mixing a 0.2–0.3 mol / L ethylene glycol solution of choline chloride with hydrogen peroxide at a volume ratio of 50:2.5–3.5.

[0071] A titanium alloy substrate is used as the anode and graphite as the cathode, with a distance of 1.5–2 cm between them. They are placed together in an electrolyte and energized at 55–65 V for 10–15 minutes at room temperature. The anode is then removed, cleaned, and dried to prepare a rough, porous structure. In one specific embodiment, the low surface energy material in step (b) is selected from at least one of fatty acids, siloxanes, or fluorosilane organic compounds; preferably at least one of siloxanes or fluorosilane organic compounds; more preferably at least one of polydimethylsiloxane emulsion or 1H,1H,2H,2H-perfluorodecyltrimethoxysilane.

[0072] When the low surface energy substance is a fatty acid, m / V / S = 0.426 g / L / cm 2 ~1.279g / L / cm 2 ;

[0073] When the low surface energy material is a siloxane, m / V / S = 0.213 g / L / cm 2 ~0.639g / L / cm 2 ;

[0074] When the low surface energy material is a fluorosilane, m / V / S = 0.0342 g / L / cm 2 ~0.068g / L / cm 2 .

[0075] In one specific embodiment, the heating in step (b) is performed by resistance heating, and the temperature of the resistance heating is controlled above the melting point and below the boiling point of the low surface energy material.

[0076] In one specific embodiment, the contact described in step (b) is carried out in a closed container, where a titanium alloy substrate is placed with a low surface energy material spaced 3-5 cm apart and heated to allow gaseous molecules to undergo saturated adsorption on the surface of the titanium alloy substrate.

[0077] In one specific embodiment, the chemical bonding reaction described in step (c) is carried out under heating conditions, so that the functional groups of low surface energy molecules react with the active groups on the surface of the titanium alloy to form chemical bonds, thereby firmly bonding to the matrix in the form of chemical bonds.

[0078] In one specific embodiment, the low surface energy substance is a fatty acid, and the heating conditions in step (c) are to heat to 100-150°C, hold for 30-90 min, and cool to room temperature; the heating rate is preferably 10°C / min.

[0079] In one specific embodiment, the low surface energy material is a siloxane or a fluorosilane, and the heating conditions in step (c) are to raise the temperature to 180-220°C, hold it at that temperature for 30-90 minutes, and then cool it to room temperature.

[0080] The preparation process of this invention is carried out under normal pressure and without inert gas protection, without the participation of organic solvents or subsequent curing treatment.

[0081] The second objective of this invention is to provide a durable superhydrophobic titanium alloy surface.

[0082] To achieve the second objective of this invention, the durable superhydrophobic titanium alloy surface is prepared using the method described above;

[0083] The durable superhydrophobic titanium alloy surface has a micro-nano rough structure and a low surface energy organic coating. The low surface energy molecules in the organic coating are chemically bonded to the micro-nano rough structure surface of the titanium alloy. The water contact angle of the durable superhydrophobic titanium alloy surface is greater than 150°.

[0084] Preferably, the surface of the durable superhydrophobic titanium alloy is peeled off with tape 100 times, and the surface water contact angle is greater than 145°.

[0085] The durable superhydrophobic titanium alloy has a linear friction distance of 2000cm and a water contact angle of over 140°.

[0086] The durable superhydrophobic titanium alloy surface, when immersed for 240 hours under conditions of pH=2 or pH=12, has a surface water contact angle of 135° or higher, preferably 140° or higher.

[0087] More preferably, after the durable superhydrophobic titanium alloy surface is impacted with water for 60 minutes, the contact angle is above 148°.

[0088] The low surface energy organic coating has a thickness of nanometers, uniformly covers the surface of the titanium alloy micro-nano structure, and fills some of the pores, thereby improving the surface's mechanical strength and chemical stability.

[0089] The specific embodiments of the present invention will be further described below with reference to examples, but the present invention is not limited to the scope of the embodiments described herein.

[0090] Example 1

[0091] The specific preparation process of the superhydrophobic titanium alloy surface modified with fatty acid-based low surface energy materials is as follows:

[0092] S1. Under the action of a magnetic heating stirrer, 14.25 g of choline chloride was dissolved in 400 mL of ethylene glycol solution at 50 °C to obtain a choline chloride ethylene glycol solution. The choline chloride ethylene glycol solution was mixed with 30% hydrogen peroxide at a volume ratio of 50:3 and stirred for 10 min to prepare the electrolyte.

[0093] S2. The titanium substrate is used as the anode and the graphite is used as the cathode, with a 2cm gap between them. The substrate is placed in the electrolyte and energized at 60V for 10 minutes at room temperature. The titanium substrate is then removed, cleaned, and dried to prepare a porous structure.

[0094] S3. Weigh 1g of myristic acid (boiling point 319.6±5℃) and place it in a container. Mix it with a pretreated container with an area of ​​5cm². 2 The titanium matrix sample was placed together with the titanium matrix sample in a sealed petri dish, with a 4 cm gap between the myristic acid and the titanium matrix. The volume of the petri dish was 0.235 L, i.e., m / V / S = 0.851 g / L / cm³. 2 .

[0095] S4. Place the above culture dish into a muffle furnace and heat it to 100°C at a rate of 10°C / min. Hold the temperature for 60 minutes, cool it to room temperature, and then remove it to obtain a highly stable superhydrophobic surface.

[0096] The morphology of the prepared samples was observed using a scanning electron microscope, and the contact angles were measured using a contact angle meter. Figure 1As shown in Figure a, it can be seen that the superhydrophobic surface prepared by this method is successful, with a contact angle of 163.4°. A water impact test was performed on the sample at a flow rate of 8 m / s and a spray distance of approximately 10 cm. After 4 minutes of water impact, the contact angle suddenly dropped to 138°. The contact angle image is shown below. Figure 2 As shown; the sample was immersed in an HCl solution with pH=2, and the contact angle results are as follows. Figure 3 As shown, under an acidic environment of 240h, its hydrophobicity gradually decreased and eventually remained at 133°; when the sample was immersed in a NaOH solution with pH=12, its hydrophobicity was completely lost in just 2h, and it became superhydrophilic, with the contact angle becoming 0°, and the surface modification layer was completely decomposed.

[0097] Example 2

[0098] The specific preparation process of the superhydrophobic titanium alloy surface modified with siloxane-based low surface energy materials is as follows:

[0099] S1. Under the action of a magnetic heating stirrer, 14.25 g of choline chloride was dissolved in 400 mL of ethylene glycol solution at 50 °C to obtain a choline chloride ethylene glycol solution. The choline chloride ethylene glycol solution was mixed with 30% hydrogen peroxide at a volume ratio of 50:3 and stirred for 10 min to prepare the electrolyte.

[0100] S2. The titanium substrate is used as the anode and the graphite is used as the cathode, with a 2cm gap between them. The substrate is placed in the electrolyte and energized at 60V for 10 minutes at room temperature. The titanium substrate is then removed, cleaned, and dried to prepare a porous structure.

[0101] S3. Weigh 0.5g of polydimethylsiloxane emulsion (boiling point 230±5℃) and place it in a container. Mix it with a pretreated emulsion with an area of ​​5cm². 2 The titanium-based sample was placed together in a petri dish and sealed. The polydimethylsiloxane emulsion and the titanium matrix were placed 4 cm apart. The volume of the petri dish was 0.235 L, i.e., m / V / S = 0.426 g / L / cm³. 2 .

[0102] S4. Place the above culture dish into a muffle furnace and heat it to 220°C at a rate of 10°C / min. Hold the temperature for 60 minutes, cool it to room temperature, and then remove it to obtain a highly stable superhydrophobic surface.

[0103] The morphology of the samples was observed using a scanning electron microscope, and the water contact angle was measured using a contact angle meter. The results are as follows: Figure 1 As shown in b, the superhydrophobic surface prepared by the new method is clearly successful, with a contact angle of 162.7°. The sample was subjected to a water impact resistance test using the method described in Example 1, and the contact angle image is shown below. Figure 4As shown, its superhydrophobic surface stability is significantly improved compared to the sample prepared in Example 1, maintaining a contact angle of 140° after 60 minutes of water impact. The sample was tested for acid and alkali resistance using the method described in Example 1. Under acidic conditions, the results are as follows... Figure 5 As shown, after 144 hours, its contact angle decreased to 126°; under alkaline conditions, the results are as follows. Figure 6 As shown, after 240 hours, its contact angle remained at 135°, demonstrating a significant improvement in its resistance to alkalinity compared to Example 1. The difference in chemical stability between Example 2 and Example 1 is due to the different types of surface organic matter, resulting in different phenomena under acidic and alkaline conditions.

[0104] Example 3

[0105] The specific preparation process of the superhydrophobic titanium alloy surface modified with fluorosilane-based low surface energy materials is as follows:

[0106] S1. Under the action of a magnetic heating stirrer, 14.25 g of choline chloride was dissolved in 400 mL of ethylene glycol solution at 50 °C to obtain a choline chloride ethylene glycol solution. The choline chloride ethylene glycol solution was mixed with 30% hydrogen peroxide at a volume ratio of 50:3 and stirred for 10 min to prepare the electrolyte.

[0107] S2. The titanium substrate is used as the anode and the graphite is used as the cathode, with a 2cm gap between them. The substrate is placed in the electrolyte and energized at 60V for 10 minutes at room temperature. The titanium substrate is then removed, cleaned, and dried to prepare a porous structure.

[0108] S3. Weigh 0.04 g of 1H,1H,2H,2H-perfluorodecyltrimethoxysilane (boiling point 250±40℃) and place it in a container. Then, mix it with a pretreated container with a surface area of ​​5 cm². 2 The titanium matrix sample was placed together with the titanium matrix sample in a sealed petri dish. The 1H,1H,2H,2H-perfluorodecyltrimethoxysilane was placed 4 cm apart from the titanium matrix. The volume of the petri dish was 0.235 L, i.e., m / V / S = 0.034 g / L / cm³. 2 .

[0109] S4. Place the above culture dish into a muffle furnace and heat it to 220°C at a rate of 10°C / min. Hold the temperature for 60 minutes, cool it to room temperature, and then remove it to obtain a highly stable superhydrophobic surface.

[0110] The morphology of the samples was observed using a scanning electron microscope, and the water contact angle was measured using a contact angle meter. The results are as follows: Figure 1 As shown in Figure c, the superhydrophobic surface prepared by this method is successful, with a contact angle of 168.8°. The sample was subjected to a water impact resistance test using the method described in Example 1, and the results are as follows... Figure 7 As shown, after 60 minutes of water impact, the contact angle remained at 148°, demonstrating a significant improvement in the mechanical stability of its superhydrophobic surface compared to the samples prepared in Examples 1 and 2. Acid and alkali resistance tests were performed on the samples using the method described in Example 1. Contact angle images under acidic conditions are shown below. Figure 8 As shown, its resistance to acid corrosion is improved compared to Examples 1 and 2. Under 240 hours of acidic environment, its contact angle remains at 144°; under alkaline environment, the results are as follows... Figure 9 As shown, under alkaline conditions for 240 hours, the final contact angle of this sample remained at 141°, demonstrating better resistance to alkaline corrosion compared to the samples prepared in Examples 1 and 2. In terms of both mechanical and chemical stability, Example 3 showed a significant improvement in stability compared to the samples prepared in Examples 1 and 2. This is attributed to the strong bonding between the surface organic matter and the metal matrix, the protection of the organic matter by the porous structure, and the chemical inertness of the organic matter, thereby enhancing its resistance to chemical corrosion.

[0111] Example 4

[0112] Referring to the method in Example 1, the heating temperatures for four sets of S4 steps were set. The heating and chemical bonding reaction of the low surface area material were carried out in the evaporation chamber. Under this heating condition, the low surface area material evaporated into gaseous molecules and then underwent a chemical bonding reaction with the surface of the metal substrate. Key process parameters and the water contact angle of the product are detailed in Table 1.

[0113] Table 1. Experimental parameters and water contact angle for Example 4.

[0114]

[0115] Note: A water contact angle <150° is considered a failure. As shown in Table 1, the experiment was successful when the heating temperature was between 100-150℃.

[0116] Example 5

[0117] Referring to the method of Example 2, the heating temperatures for three sets of S4 steps were set. The heating and chemical bonding reaction of the low surface area material were carried out in the evaporation chamber. Under this heating condition, the low surface area material evaporated into gaseous molecules and then underwent a chemical bonding reaction with the surface of the metal substrate. Key process parameters and the water contact angle of the product are detailed in Table 2.

[0118] Table 2 Experimental parameters and water contact angle of Example 5

[0119]

[0120] As shown in Table 2, siloxanes, as low surface energy materials, were successfully tested at heating temperatures between 180-220℃.

[0121] Example 6

[0122] Referring to the method in Example 3, three different amounts of fluorosilane were set up. The key process parameters and the water contact angle of the product are detailed in Table 3.

[0123] Table 3 Experimental parameters and water contact angle of Example 6

[0124]

[0125] As shown in Table 3, the experiment was successful when fluorosilane, as a low surface energy substance, was used in amounts ranging from 0.04 g to 0.08 g.

[0126] Comparative Example 1

[0127] Comparative Example 1 was not structured, so steps S1 and S2 were omitted. Experimental parameters and water contact angles are detailed in Table 4.

[0128] Table 4. Experimental parameters and water contact angle of Comparative Example 1

[0129]

[0130] Comparative Example 2

[0131] The sample, after being treated in the same way as steps S1 and S2 of Example 1, was immersed in a 0.1M anhydrous ethanol solution of tetradecanoic acid for 30 minutes. After immersion, it was removed and dried.

[0132] The products of Example 1 and Comparative Example 2 were tested as follows:

[0133] Tape peeling:

[0134] Peel resistance tests were conducted using 3M transparent tape to assess the superhydrophobic surface's resistance to peeling. With the superhydrophobic surface facing upwards, the tape was completely covered. Pressure was applied to ensure a tight bond, and then the tape was peeled off, completing one peel cycle. Fresh tape was used for each peel. Detailed test results can be found in [link to test results]. Figure 11 .

[0135] Linear friction:

[0136] The abrasion resistance of the superhydrophobic surface was tested using a linear tribological test. The superhydrophobic surface was placed face down on a sheet of 800-grit sandpaper and moved at a constant speed with a load of 100g. Fresh sandpaper was used for each abrasion test. See [link to test results] for details. Figure 12 .

[0137] Water impact resistance:

[0138] Water impact tests were conducted on the samples. A nozzle with a diameter of 5 mm was used, and the flow rate was 8 m / s (flow rate: 9.5 L / min). The water was sprayed onto the sample surface at approximately a vertical angle, with a spray distance of approximately 10 cm. Detailed test results can be found in [link to test results]. Figure 13 .

[0139] Acid and alkali resistance:

[0140] The superhydrophobic sample was immersed in HCl solution (pH=2) and NaOH solution (pH=12) to test the acid and alkali corrosion resistance of the superhydrophobic surface. See the detailed test results below. Figure 14 .

[0141] The polydimethylsiloxane in Example 2 has a large molecular weight, making it unsuitable for preparing superhydrophobic surfaces via immersion modification. Existing techniques typically use it as a component of coatings to prepare superhydrophobic coatings. Example 2 is compared with previously reported superhydrophobic coatings containing polydimethylsiloxane (PDMS), as detailed in Tables 5 and 6. Figure 15 .

[0142] Table 5 compares the tribological results of superhydrophobic metal surfaces prepared by different methods using PDMS as the low-energy material.

[0143]

[0144] Table 6 compares the acid and alkali resistance of superhydrophobic metal surfaces prepared by different methods using PDMS as a low-energy material.

[0145]

[0146] Comparative Example 3

[0147] The sample, after being treated in the same way as steps S1 and S2 of Example 3, was immersed in a 0.03M solution of 1H, 1H, 2H, 2H-perfluorodecyltrimethoxysilane in anhydrous ethanol for 30 minutes. After immersion, it was removed and dried.

[0148] The products of Example 3 and Comparative Example 3 were tested as follows:

[0149] For detailed tape peel test results, please refer to [link / reference]. Figure 16 .

[0150] For detailed results of the linear friction test, please refer to Figure 17 .

[0151] For detailed results of the water impact resistance test, please refer to Figure 18 .

[0152] For detailed acid and alkali resistance test results, please refer to Figure 19 .

[0153] Resistance to neutral salt spray:

[0154] The resistance of the superhydrophobic surface to neutral salt spray corrosion was tested. The salt spray was a 5% sodium chloride solution, and the test temperature was 30°C. The comparative test results of Examples 1, 2, 3, and 3 after 96 hours of salt spray testing are detailed below. Figure 20 .

[0155] For details of the water contact angle diagram after 30 days of salt spray testing in Example 3, please refer to [link / reference]. Figure 21 .

[0156] Comparative Example 4

[0157] Electroplated vapor-deposited PDMS [1] Micro-arc oxidation followed by vapor deposition of PDMS [2] The results of linear friction and acid and alkali resistance tests were compared with those of Example 2. The results are detailed in Table 7, and the comparison of acid and alkali resistance tests is detailed in Table 8.

[0158] Table 7 Comparison of friction tests on superhydrophobic metal surfaces prepared by vapor deposition method

[0159]

[0160] Table 8 Comparison of acid and alkali resistance tests on superhydrophobic metal surfaces prepared by vapor deposition method.

[0161]

[0162] Post-electroplating vapor deposition of PDMS [1] This was prepared using existing technology. (Ye Y, Kang Z, Wang F, et al. Achieving hierarchical structure with superhydrophobicity and enhanced anti-corrosion via electrochemical etching and chemical vapor deposition[J]. Applied Surface Science, 2023, 610: 155362.)

[0163] Micro-arc oxidation followed by vapor deposition of PDMS [2]This was prepared using existing technology. (Ma Y, Hu Y, Yu Z, et al. Dual-layer TiO2 / PDMS composite coating on Ti6Al4V titanium alloy with superhydrophobicity and enhanced corrosion resistance and mechanical stability[J]. Surface and Coatings Technology, 2025: 132414.)

Claims

1. A method for preparing a durable superhydrophobic titanium alloy surface, characterized in that, The method includes the following steps: (a) The surface of the titanium alloy substrate is pretreated to form a highly active multi-site micro-nano rough structure; (b) A titanium alloy substrate with m grams of low surface energy material and a surface area of ​​S square centimeters, after pretreatment in step (a), is placed in a sealed space with a volume of V liters. The low surface energy material is heated and evaporated into gaseous molecules at a temperature below the boiling point. The titanium alloy substrate after pretreatment in step (a) comes into contact with the gaseous molecules, which are deposited and adsorbed onto the micro / nano rough structure surface of the titanium alloy substrate. The m / V / S ratio is 0.034 g / L / cm². 2 ~1.279g / L / cm 2 ; (c) After adsorption is complete, the low surface energy molecules on the titanium alloy surface undergo a chemical bonding reaction with the titanium alloy matrix to form a superhydrophobic coating, thus obtaining a durable superhydrophobic titanium alloy surface.

2. The method for preparing a durable superhydrophobic titanium alloy surface according to claim 1, characterized in that, (a) The pretreatment described in step (a) includes at least one of mechanical roughening, chemical etching, electrochemical etching, anodic oxidation, micro-arc oxidation, or hydrothermal alkaline treatment.

3. The method for preparing a durable superhydrophobic titanium alloy surface according to claim 2, characterized in that, The preprocessing includes: Prepare the electrolyte by mixing a 0.2–0.3 mol / L ethylene glycol solution of choline chloride with hydrogen peroxide at a volume ratio of 50:2.5–3.

5. A titanium alloy substrate was used as the anode and graphite as the cathode, with a distance of 1.5 to 2 cm between them. They were placed together in an electrolyte and energized at 55 to 65 V for 10 to 15 minutes at room temperature. The anode was then removed, cleaned, and dried to prepare a rough porous structure.

4. The method for preparing a durable superhydrophobic titanium alloy surface according to claim 1 or 2, characterized in that, (b) The low surface energy material mentioned in step is selected from at least one of fatty acids, siloxanes or fluorosilanes; preferably at least one of siloxanes or fluorosilanes; more preferably at least one of polydimethylsiloxane emulsion or 1H,1H,2H,2H-perfluorodecyltrimethoxysilane. When the low surface energy substance is a fatty acid, m / V / S = 0.426 g / L / cm 2 ~1.279g / L / cm 2 ; When the low surface energy material is a siloxane, m / V / S = 0.213 g / L / cm 2 ~0.639g / L / cm 2 ; When the low surface energy material is a fluorosilane, m / V / S = 0.034 g / L / cm 2 ~0.068g / L / cm 2 .

5. The method for preparing a durable superhydrophobic titanium alloy surface according to claim 1 or 2, characterized in that, (b) The heating in step A is performed by resistance heating, and the temperature of the resistance heating is controlled above the melting point and below the boiling point of the low surface energy material.

6. The method for preparing a durable superhydrophobic titanium alloy surface according to claim 1 or 2, characterized in that, (b) The contact described in step A is carried out in a closed container. The titanium alloy substrate is placed with a gap of 3 to 5 cm between it and a low surface energy material and heated to allow gaseous molecules to be saturated and adsorbed on the surface of the titanium alloy substrate.

7. The method for preparing a durable superhydrophobic titanium alloy surface according to claim 1 or 2, characterized in that, (c) The chemical bonding reaction described in step (c) is carried out under heating conditions, so that the functional groups of low surface energy molecules react with the active groups on the surface of titanium alloy to form chemical bonds, thereby firmly bonding to the matrix in the form of chemical bonds.

8. The method for preparing a durable superhydrophobic titanium alloy surface according to claim 7, characterized in that, The low surface energy substance is a fatty acid. The heating conditions in step (c) are to heat to 100-150°C, hold for 30-90 min, and cool to room temperature. The preferred heating rate is 10°C / min.

9. The method for preparing a durable superhydrophobic titanium alloy surface according to claim 6, characterized in that, The low surface energy material is a siloxane or fluorosilane. The heating conditions in step (c) are to raise the temperature to 180-220°C, hold for 30-90 minutes, and then cool to room temperature.

10. A durable superhydrophobic titanium alloy surface, characterized in that: The durable superhydrophobic titanium alloy surface is prepared by the method described in any one of claims 1 to 9; The durable superhydrophobic titanium alloy surface has a micro-nano rough structure and a low surface energy organic coating. The low surface energy molecules in the organic coating are chemically bonded to the micro-nano rough structure surface of the titanium alloy. The water contact angle of the durable superhydrophobic titanium alloy surface is greater than 150°. Preferably, the surface of the durable superhydrophobic titanium alloy is peeled off with tape 100 times, and the surface water contact angle is greater than 145°. The durable superhydrophobic titanium alloy has a linear friction distance of 2000cm and a water contact angle of over 140°. The durable superhydrophobic titanium alloy surface, when immersed for 240 hours under conditions of pH=2 or pH=12, has a surface water contact angle of 135° or higher, preferably 140° or higher. More preferably, after the durable superhydrophobic titanium alloy surface is impacted with water for 60 minutes, the contact angle is above 148°.

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