A biomimetic super-hydrophobic wear-resistant anticorrosion coating and a preparation method thereof

Abstract

The application belongs to the technical field of functional materials, and particularly relates to a kind of bionic super-hydrophobic wear-resistant anticorrosion coating and its preparation method, the preparation method of the application is prepared ZIF-90 particle as framework first, then carries out hydrophobic treatment to obtain ZIF-90 / STA solution, is dispersed in polyvinyl butyral matrix again, finally, ZSP composite coating is obtained by casting film on the surface of magnesium alloy.The preparation process of the application is simple, raw materials are easy to obtain, and complex equipment is not needed.The composite coating prepared has excellent wear resistance, super-hydrophobic surface, and greatly improves the corrosion resistance and durability of magnesium alloy, effectively solves the problems of poor corrosion resistance, hydrophobicity and environmental friendliness of magnesium alloy.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of functional materials, and particularly relates to a kind of bionic super-hydrophobic wear-resistant anticorrosion coating and its preparation method. BACKGROUND

[0002] Magnesium alloy is the lightest structural metal, and has good electromagnetic shielding, high specific strength and thermal conductivity, good biocompatibility. In addition, it also has good machinability, casting ability and ductility. These excellent properties make magnesium alloy widely used in aerospace, automobile, military, biomedical devices and many other fields. However, the standard electrode potential of magnesium alloy is low, the chemical reaction activity is high, and the surface oxide film is loose and porous, which makes it easy to be corroded in humid environment or chloride-containing corrosive medium. The poor corrosion resistance of magnesium alloy seriously hinders its development and practical application.

[0003] Polymer coating as an effective physical barrier layer can resist the attack of corrosive ions in the use environment, block the ion transmission path, and play a role in preventing corrosion of the magnesium alloy substrate. Inspired by the water-repellent property of lotus leaves and other animals and plants in nature, combining this property with corrosion-resistant coating, the resulting biomimetic super-hydrophobic coating can capture air at the interface between the coating and the substrate, forming an air layer, reducing the area and time of contact between the coating and the corrosive medium, and better improving the corrosion resistance of the coating. Generally, using low-surface-energy substances to modify particles with micro-nano structures can meet the basic conditions for preparing super-hydrophobic coatings. ZIF-90 developed by Yaghi team has SOD topological structure, and has high thermal stability and chemical stability, and can still maintain stable crystal structure at 500 DEG C, so ZIF-90 with nano structure is often used to provide the necessary surface roughness for the construction of super-hydrophobic coating. However, the low-surface-energy substances commonly used to modify ZIF-90 have fluorine-containing segments, which means that they will cause environmental burden and hinder the recycling of magnesium alloy. At the same time, many super-hydrophobic coatings will lose their super-hydrophobicity after being rubbed and worn for many times, which will reduce the corrosion resistance. In view of the above, how to design and develop a green, wear-resistant and durable magnesium alloy corrosion-resistant coating based on ZIF-90 is a research topic worth studying. SUMMARY

[0004] In view of the above deficiencies mentioned in the background art, the purpose of the present application is to provide a kind of bionic super-hydrophobic wear-resistant anticorrosion coating and its preparation method.

[0005] In order to achieve the above purpose, the present application provides a kind of bionic super-hydrophobic wear-resistant anticorrosion coating and its preparation method, which comprises the following steps:

[0006] S1: take zinc source, imidazole-2-formaldehyde and formate separately dissolved in methanol, add the methanol mixed solution of imidazole-2-formaldehyde and formate to the methanol solution of zinc source, stir uniformly, then put the mixed solution into a reaction kettle for solvothermal reaction, then high-speed centrifugal separation, take the precipitate, wash and dry to obtain ZIF-90 particles;

[0007] S2: add the ZIF-90 particles obtained in S1 and long-chain stearic acid to anhydrous ethanol, stir and ultrasonically disperse to obtain a ZIF-90 / STA solution;

[0008] S3: take polyvinyl butyral and dissolve it in anhydrous ethanol, then add the obtained solution to the ZIF-90 / STA solution obtained in S2, and ultrasonically obtain a ZIF-90 / STA / PVB solution;

[0009] S4: cast the ZIF-90 / STA / PVB solution obtained in S3 to the surface of a clean magnesium alloy, dry into a film to obtain a biomimetic super-hydrophobic wear-resistant corrosion-resistant coating ZIF-90 / STA / PVB (abbreviated as ZSP coating).

[0010] In the technical solution, ZIF-90 is used as the skeleton for constructing the surface microstructure, wherein metal zinc source and imidazole-2-formaldehyde are used as organic ligands, ZIF-90 with stable structure is grown in a reaction kettle, then long-chain stearic acid (STA) is introduced to reduce the surface energy and improve the hydrophobicity, finally ZIF-90 and STA are uniformly dispersed in a polyvinyl butyral (PVB) matrix, and the composite coating is cast into a film on the surface of a magnesium alloy. The preparation process of the present application is simple, the raw materials are easy to obtain, and no complex equipment is needed. The composite coating prepared has excellent wear resistance, super-hydrophobic surface, and greatly improved corrosion resistance and corrosion durability of the magnesium alloy.

[0011] Further, in the technical solution S1, the molar ratio of the zinc source, imidazole-2-formaldehyde and formate is 1: (2-4) : (1-5).

[0012] Further, in the technical solution S1, the zinc source is zinc nitrate hexahydrate or zinc chloride.

[0013] Further, in the technical solution S1, the formate is an optional formate, preferably sodium formate, potassium formate or calcium formate.

[0014] Further, in the technical solution S1, the temperature of the solvothermal reaction is 120-160℃, and the reaction time is 8-12h.

[0015] Further, in the technical solution S1, the solution used for washing is slightly methanol, and the washing is repeated 3-5 times.

[0016] Further, in the technical solution S1, the rotation speed of the high-speed centrifugation is 6000-8000 rpm.

[0017] Further, in the technical solution S2, the mass ratio of the ZIF-90 particles and the long-chain stearic acid is 1:(5-10).

[0018] The application further provides a biomimetic super-hydrophobic wear-resistant corrosion-resistant coating prepared by the preparation method.

[0019] Compared with the prior art, the application has the following beneficial effects:

[0020] The application uses ZIF-90 particles as a skeleton for constructing a surface microstructure, and then uses green and environmentally friendly long-chain stearic acid to modify the ZIF-90 nanoparticles, which not only effectively avoids the use of fluorine-containing materials that have a burden on the environment, but also greatly improves the hydrophobicity; then the ZIF-90 nanoparticles are dispersed in a polyvinyl butyral matrix and cast into a film on the surface of a magnesium alloy, and the obtained ZSP composite coating has excellent corrosion resistance and durability in a salt solution, and also has good super-hydrophobicity and wear resistance, and excellent performance.

[0021] The preparation process of the ZSP composite coating is simple, and the ZSP composite coating can be obtained without complex equipment, and is widely applicable. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments or the prior art description will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments described in the present application, and other drawings can also be obtained by those skilled in the art without creative labor.

[0023] Figure 1 The preparation flow chart of the ZSP composite coating in Example 1 of the present application is shown in FIG. 1.

[0024] Figure 2 In FIG. 2, a, b, c, and d are SEM, TEM, XRD, and FTIR diagrams of the ZIF-90 particles prepared in Example 1 of the present application.

[0025] Figure 3 In FIG. 3, a, b, c, and d are contact angle, AFM, SEM, and contact angle wear resistance curve diagrams of the ZSP composite coating prepared in Example 1 of the present application.

[0026] Figure 4 The polarization curve diagram of the ZSP composite coating prepared in Example 1 of the present application, the PVB coating of the control group, and the AZ31B magnesium alloy in a 3.5wt% NaCl solution is shown in FIG. 4.

[0027] Figure 5 Fig. 8 is a contact angle abrasion resistance curve of Nyquist and Bode plots of ZSP composite coating prepared in Example 1 of the present application, PVB coating of the control group and AZ31B magnesium alloy in 3.5wt% NaCl solution; Figure 5 Fig. 9 is a Nyquist and Bode plot of ZSP composite coating prepared in Example 1 of the present application in 3.5wt% NaCl solution after different time of immersion; Figure 5 Fig. 10 is an equivalent circuit diagram of AZ31B magnesium alloy and ZSP composite coating prepared in Example 1 of the present application in 3.5wt% NaCl solution. DETAILED DESCRIPTION

[0028] The experimental methods in the following examples are all conventional methods unless otherwise specified. The raw materials involved in the following examples are all ordinary commercially available products and can be purchased on the market unless otherwise specified.

[0029] The above technical features of the present application and the technical features described in detail in the following (such as the implementation case) can be combined with each other to form new or preferred technical solutions.

[0030] The raw materials involved in the embodiments of the present application are either existing commercially available products or can be prepared according to existing methods.

[0031] The specific content of the present application is further explained and described below in combination with examples.

[0032] Example 1

[0033] A preparation method of a biomimetic super-hydrophobic wear-resistant corrosion-resistant coating, comprising the following steps:

[0034] S1: Dissolve zinc nitrate hexahydrate (0.297 g), imidazole-2-formaldehyde (0.193 g) and sodium formate (0.069 g) in methanol (concentration > 99.5%) respectively to obtain solution A and solution B, add solution B to solution A, stir until uniform to obtain solution C, put the mixed solution C into a reaction kettle and perform solvothermal reaction at 150°C for 8h, centrifuge the precipitate at a speed of 6000 rpm, wash the centrifuged precipitate with methanol (concentration > 99.5%) for 3 times, dry at 70°C for 12h to obtain the product ZIF-90 particles;

[0035] S2: Add 0.01 g of ZIF-90 particles and 0.05 g of STA (long-chain stearic acid) to 2 mL of anhydrous ethanol, stir and ultrasonically disperse to obtain a ZIF-90 / STA solution;

[0036] S3: 0.8 g PVB (polyvinyl butyral) was dissolved in 9.2 mL of anhydrous ethanol, and then 2 mL of the PVB solution was added to the ZIF-90 / STA solution obtained in S2, and ultrasonic dispersion was performed to obtain a ZIF-90 / STA / PVB solution;

[0037] S4: The surface of the magnesium alloy was polished with 1200 grit sandpaper, and then washed with acetone and anhydrous ethanol under ultrasonic conditions, and dried to obtain a clean magnesium alloy without a surface oxide film and oil stains. The ZIF-90 / STA / PVB solution obtained in S3 was cast onto the surface of the clean magnesium alloy, and dried to form a film to obtain a biomimetic super-hydrophobic wear-resistant corrosion-resistant ZSP coating. Figure 1

[0038] Example 2

[0039] A method for preparing a biomimetic super-hydrophobic wear-resistant corrosion-resistant coating, comprising the following steps:

[0040] S1: Zinc nitrate hexahydrate (0.446 g), imidazole-2-formaldehyde (0.336 g), and sodium formate (0.136 g) were dissolved in methanol (concentration > 99.5%) to obtain solution A and solution B. Solution B was added to solution A, and stirring was performed until the solution was uniform to obtain solution C. The mixture C was placed in a reaction kettle and subjected to a solvothermal reaction at 130°C for 10 h. The precipitate was separated by high-speed centrifugation at a speed of 6000 rpm, and the centrifuged precipitate product was washed with methanol (concentration > 99.5%) in three times. After drying at 70°C for 12 h, the product ZIF-90 particles were obtained.

[0041] S2: 0.005 g of ZIF-90 and 0.035 g of STA were added to 2 mL of anhydrous ethanol, and stirring and ultrasonic dispersion were performed to obtain a ZIF-90 / STA solution.

[0042] S3: 0.4 g of PVB was dissolved in 5.6 mL of anhydrous ethanol, and then 2 mL of the PVB solution was added to the ZIF-90 / STA solution obtained in S2, and ultrasonic dispersion was performed to obtain a ZIF-90 / STA / PVB solution.

[0043] S4: The surface of the magnesium alloy was polished with 1200 grit sandpaper, and then washed with acetone and anhydrous ethanol under ultrasonic conditions, and dried to obtain a clean magnesium alloy without a surface oxide film and oil stains. The ZIF-90 / STA / PVB solution obtained in S3 was cast onto the surface of the clean magnesium alloy, and dried to form a film to obtain a biomimetic super-hydrophobic wear-resistant corrosion-resistant ZSP coating.

[0044] Example 3

[0045] A method for preparing a biomimetic super-hydrophobic wear-resistant corrosion-resistant coating, comprising the following steps: ​

[0046] S1: Dissolve zinc nitrate hexahydrate (0.594 g), imidazole-2-carboxaldehyde (0.403 g) and sodium formate (0.238 g) in methanol (concentration > 99.5%) respectively to obtain solution A and solution B, add solution B to solution A, stir to uniformity to obtain solution C, place the mixed solution C into a reaction kettle and carry out a solvothermal reaction at 120°C for 12 h, centrifugally separate the precipitate at a speed of 6000 rpm, wash the centrifugally separated product with methanol (concentration > 99.5%) in three times, dry at 70°C for 12 h to obtain product ZIF-90 particles;

[0047] S2: Add 0.008 g of ZIF-90 and 0.048 g of STA to 2 mL of anhydrous ethanol, stir and ultrasonically disperse to obtain a ZIF-90 / STA solution;

[0048] S3: Dissolve 1.2 g of PVB in 13.8 mL of anhydrous ethanol, then take 2 mL of the PVB solution and add to the ZIF-90 / STA solution obtained in S2, ultrasonically disperse to obtain a ZIF-90 / STA / PVB solution;

[0049] S4: Polish the surface of the magnesium alloy with 1200 grit sandpaper, ultrasonically wash with acetone and anhydrous ethanol, dry to obtain a clean magnesium alloy without surface oxidation film and oil stains, cast the ZIF-90 / STA / PVB solution obtained onto the surface of the clean magnesium alloy, dry to form a film to obtain a biomimetic super-hydrophobic wear-resistant corrosion-resistant ZSP coating.

[0050] Test Example

[0051] The material prepared in Example 1 was respectively subjected to characterization tests.

[0052] 1. Analyze the prepared ZIF-90 particles

[0053] The SEM and TEM images of the ZIF-90 particles are shown in Figure 2 a and b, it can be seen that the ZIF-90 particles have a nanometer size and can provide the required roughness for the hydrophobic coating. The XRD spectrum of the prepared ZIF-90 particles is shown in Figure 2 c, for the ZIF-90 particles, 7.3º, 10.3º, 12.6º, 14.7º, 16.4º, 17.9º, 22.1º, 24.4º, 26.6º, 29.6º, 30.4º, 32.3º correspond to (011), (200), (112), (022), (013), (222), (114), (233), (134), (044), (244), (235) crystal faces. The FT-IR spectrum of the prepared ZIF-90 particles is shown in Figure 2 d, 1676 cm-1 The absorption peak at 1458 cm⁻¹ is attributed to the C=O stretching vibration of the aldehyde group on the imidazole ring. -1 1417 cm -1 1361 cm -1 1166 cm -1 952 cm -1 and 794 cm -1 The peak at 1307-925 cm⁻¹ is attributed to the vibration of the entire imidazole ring. -1 The peak is attributed to the vibration of the imidazole ring.

[0054] 2. Analysis of the prepared ZSP composite coating

[0055] The contact angle and abrasion resistance of the ZSP composite coating prepared in Example 1 are tested as follows: Figure 3 As shown in Figure a, water droplets are spherical on the surface of the ZSP composite coating, indicating that the obtained ZSP composite coating has excellent hydrophobic properties. Figure 3 The contact angle measurement at the upper right corner shows that the contact angle between the ZSP composite coating and water is 155º, indicating that the ZSP composite coating has superhydrophobicity. Figure 3 b and c are AFM and SEM images of the ZSP composite coating prepared in Example 1. It can be clearly seen that there are nanoscale protrusions and depressions on the surface of the ZSP composite coating, which also explains the superhydrophobic phenomenon on the surface of the ZSP coating. Figure 3 d is the curve of the contact angle of the ZSP composite coating prepared in Example 1 as a function of friction distance. The contact angle of the ZSP composite coating is still greater than 150º at a friction distance of 200cm, which shows that it has superhydrophobicity. This indicates that the prepared ZSP superhydrophobic composite coating has excellent wear resistance.

[0056] The polarization curves of the ZSP composite coating, the control group PVB coating, and the AZ31B magnesium alloy prepared in Example 1 in 3.5wt% NaCl solution are shown below. Figure 4 As shown in Table 1, the corrosion potentials of the AZ31B magnesium alloy, the control group PVB coating, and the ZSP composite coating are -1.53V, -1.47V, and -0.86V, respectively, indicating that the prepared ZSP composite coating can effectively improve the corrosion resistance of the magnesium alloy; moreover, the corrosion current density of the ZSP composite coating is 3.66 × 10⁻⁶. -12 A / cm 2 The value was less than 1.84 × 10⁻⁶ for the control group PVB coating. -7 A / cm 2 And it is much smaller than the corrosion current density of magnesium alloy, which is 1.14 × 10⁻⁶. -4 A / cm 2This also shows that the ZSP composite coating can very effectively slow down the corrosion rate of magnesium alloys; calculations show that the corrosion protection rate of the ZSP composite coating on magnesium alloys is close to 100%.

[0057] Electrochemical impedance spectroscopy (Nyquist and Bode plots) of AZ31B magnesium alloy, the ZSP composite coating prepared in Example 1, the control group PVB coating, and AZ31B magnesium alloy in 3.5 wt% NaCl solution are shown below. Figure 5 As shown in a and c. From Figure 5 As can be seen from all the impedance diagrams shown in Figure a, the AZ31B magnesium alloy substrate exhibits a relatively complete small-diameter semicircular arc, while the PVB and ZSP composite coating exhibits an incomplete large-diameter capacitive arc, with the ZSP composite coating possessing an even larger diameter capacitive arc. From Figure 5 As shown in Bode plot c, the electrochemical impedance modulus and phase angle of the ZSP composite coating are much greater than those of the PVB coating and the AZ31B magnesium alloy. Meanwhile, according to... Figure 5 According to the equivalent circuit fitting results for e and f, and Table 2, the ZSP composite coating has the highest film resistance (7.64 × 10⁻⁶) compared to the PVB coating and AZ31B magnesium alloy. 9 Ωcm 2 ) and charge transfer resistance (2.24×10 10 Ωcm 2 These results demonstrate that the ZSP composite coating can prevent corrosive media from penetrating the coating and entering the interface between the substrate and the coating, thereby effectively avoiding corrosion on the magnesium alloy substrate surface.

[0058] The Nyquist and Bode plots of the ZSP composite coating prepared in Example 1 after immersion in 3.5 wt% NaCl solution for 5 days are shown below. Figure 5 As shown in b and d, it can be seen that with the extension of immersion time, the diameter of the capacitive arc exhibited by the ZSP composite coating gradually shortens, indicating that the corrosion resistance decreases with increasing immersion time. The electrochemical impedance modulus and phase angle also decrease with increasing immersion time. According to... Figure 5 Based on the equivalent circuit fitting results and Table 3, the film resistance of the ZSP coating after 5 days of immersion is 9.14 × 10⁻⁶. 6 Ωcm 2 ) and charge transfer resistance (5.12×10 9 Ωcm 2 The value is also much larger than that of the AZ31B magnesium alloy substrate, proving that the prepared ZSP composite coating has very good long-term corrosion resistance.

[0059] Table 1. Results of sample polarization curve fitting

[0060]

[0061] Table 2. Sample electrochemical impedance fitting results

[0062]

[0063] Table 3. Electrochemical impedance fitting results of ZSP composite coating in salt solution under different treatment times

[0064]

[0065] Finally, it needs to be emphasized that the above is only the preferred embodiment of the present application, and is not intended to limit the present application. For those skilled in the art, the present application can have various changes and modifications, and any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a biomimetic superhydrophobic wear-resistant anticorrosive coating, characterized in that, Comprising the following steps: S1: take zinc source, imidazole-2-formaldehyde and formate separately dissolved in methanol, add the mixed solution of imidazole-2-formaldehyde and formate in methanol to the methanol solution of zinc source, stir uniformly, then put the mixed solution into a reaction kettle for solvothermal reaction, then high-speed centrifugal separation, take the precipitate, wash and dry to obtain ZIF-90 particles; S2: add the ZIF-90 particles obtained in S1 and long-chain stearic acid to anhydrous ethanol, stir and ultrasonic dispersion to obtain a ZIF-90 / STA solution; S3: take polyvinyl butyral dissolved in anhydrous ethanol, then add the obtained solution to the ZIF-90 / STA solution obtained in S2, ultrasonic to obtain a ZIF-90 / STA / PVB solution; S4: cast the ZIF-90 / STA / PVB solution obtained in S3 to the surface of a clean magnesium alloy, dry into a film to obtain a biomimetic super-hydrophobic wear-resistant corrosion-resistant coating ZIF-90 / STA / PVB.

2. The method according to claim 1, wherein the method is characterized by, In S1, the molar ratio of the zinc source, imidazole-2-formaldehyde and formate is 1:(2-4):(1-5).

3. The method according to claim 1, wherein the method is characterized by, In S1, the zinc source is zinc nitrate hexahydrate or zinc chloride.

4. The method of claim 1, wherein the method further comprises the step of applying a protective layer on the surface of the substrate. In S1, the formate is sodium formate, potassium formate or calcium formate.

5. The method of claim 1, wherein the method further comprises the step of applying a protective layer on the surface of the substrate. In S1, the temperature of the solvothermal reaction is 120-160℃, and the reaction time is 8-12h.

6. The method of claim 1, wherein the method further comprises the step of applying a protective layer on the surface of the substrate. In S1, the solution used for washing is methanol, and the washing is repeated for 3-5 times.

7. The method of claim 1, wherein the method further comprises the step of applying a topcoat layer on the superhydrophobic layer. In S1, the speed of high-speed centrifugation is 6000-8000rpm.

8. The method of claim 1, wherein the method further comprises the step of applying a topcoat layer on the superhydrophobic layer. In S2, the mass ratio of the ZIF-90 particles and long-chain stearic acid is 1:(5-10).

9. A biomimetic super-hydrophobic wear-resistant corrosion-resistant coating prepared by the preparation method of any one of claims 1-8.

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