A wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating, its preparation method and application

Abstract

This invention provides a wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating, its preparation method, and its application. The composite coating comprises a first coating layer, a second coating layer, and a third coating layer sequentially coated onto a metal substrate. The first coating layer comprises epoxy resin and polydimethylsiloxane. The second coating layer comprises modified ZIF-8 / SiO2 composite powder, polydimethylsiloxane, and epoxy resin. The third coating layer comprises modified ZIF-8 / SiO2 composite powder, polydimethylsiloxane, and epoxy resin. The modified ZIF-8 / SiO2 composite powder is obtained by surface grafting modification of ZIF-8 / SiO2 with a silane coupling agent. This composite coating not only imparts excellent corrosion resistance and superhydrophobicity but also improves the adhesion between the coating and the metal substrate, thereby enhancing its wear resistance. This is of great significance for the research and development of multifunctional protective coatings for offshore wind power projects.

Description

Technical Field

[0001] This invention relates to the field of polymer composite coating technology, and in particular to a wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating, its preparation method, and its application. Background Technology

[0002] Human daily life is inseparable from various metals and alloys. Due to their excellent mechanical strength, machinability and wide availability, they are often used in mechanical equipment in engineering fields such as offshore wind power, aerospace, and building construction. However, these metal and alloy materials are susceptible to the effects of corrosive environments, which can cause huge economic losses, environmental pollution and safety hazards.

[0003] Constructing superhydrophobic surfaces with contact angles greater than 150° and roll-off angles less than 10° on metal substrates has proven to be an effective corrosion protection strategy. Due to the excellent water repellency and low adhesion of superhydrophobic surfaces, the covered metal substrate can be completely isolated from external corrosive media. Furthermore, organic resin coatings are widely used in surface protection engineering due to their high adhesion and good abrasion resistance; their corrosion resistance largely depends on the coating's impermeability. However, in the face of complex and harsh marine environments, the abrasion resistance and corrosion resistance of a single superhydrophobic coating or organic resin coating are limited, which can lead to the loss of superhydrophobic properties or a significant reduction in the corrosion resistance of organic coatings. Therefore, to improve the abrasion resistance and corrosion resistance of protective coatings in marine environments, it is necessary to comprehensively consider factors such as coating structural design, material selection, and preparation processes.

[0004] Functionally graded composite coatings are a novel coating technology with significant advantages. They achieve a gradient distribution of composition and structure by preparing a gradient reinforcement layer on the substrate surface. This not only significantly improves the bonding strength within the coating and its adhesion to the substrate, but also endows the composite coating with other superior properties. Therefore, developing a composite coating that combines excellent superhydrophobicity, abrasion resistance, and corrosion resistance to adapt to different environments and usage conditions and thus achieve optimal performance is an urgent task at present. Summary of the Invention

[0005] In view of the above, the present invention provides a wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating, a preparation method, and an application. The composite coating not only endows the coating with excellent corrosion resistance and superhydrophobicity, but also improves the adhesion between the coating and the metal substrate, thereby enhancing its wear resistance.

[0006] One aspect of the present invention provides a wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating.

[0007] Another aspect of the present invention provides a method for preparing the above-mentioned wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating, including...

[0008] Another aspect of the present invention provides the application of the above-mentioned wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating, including...

[0009] Beneficial effects:

[0010] This invention presents a gradient composite coating that combines wear resistance, corrosion resistance, and superhydrophobicity, based on a modified ZIF-8 / SiO2 composite powder, an organosilicon polymer PDMS (polydimethylsiloxane), and a high-molecular-weight epoxy resin. The performance of the functionalized gradient composite coating is controlled by adjusting the proportions of each component during the preparation of each coating layer. From the side closer to the metal substrate to the side farther away, gradually increasing the proportions of the modified ZIF-8 / SiO2 composite powder and the organosilicon polymer PDMS in each coating layer gradually enhances the hydrophobicity of the coating surface. Conversely, from the side farther away from the metal substrate to the side closer to the metal substrate, gradually increasing the proportions of the high-molecular-weight epoxy resin in each coating layer gradually enhances the adhesion of the coating. Compared to traditional single protective coatings, this gradient composite coating exhibits excellent superhydrophobic properties while simultaneously improving its density, stability, wear resistance, and corrosion resistance.

[0011] Furthermore, the preparation method of the wear-resistant and corrosion-resistant superhydrophobic gradient composite coating provided by this invention has a simple process flow, mild reaction conditions, low energy consumption, and is suitable for large-scale production. It is of great significance for the research on developing multifunctional protective coatings for offshore wind power projects. Attached Figure Description

[0012] Figure 1 Corrosion resistance test graphs of the gradient composite coatings prepared in each embodiment and comparative example in 3.5 wt% NaCl solution;

[0013] Figure 2 The graph shows the contact angle variation of the gradient composite coatings prepared in each embodiment and comparative example for wear resistance testing. Detailed Implementation

[0014] To facilitate understanding of the present invention, a more complete description will be given below with reference to various embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

[0015] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0016] This invention provides a wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating, comprising a first coating layer, a second coating layer, and a third coating layer sequentially coated on a metal substrate. The first coating layer comprises epoxy resin and polydimethylsiloxane. The second coating layer comprises modified ZIF-8 / SiO2 composite powder, polydimethylsiloxane, and epoxy resin. The third coating layer comprises modified ZIF-8 / SiO2 composite powder, polydimethylsiloxane, and epoxy resin. The modified ZIF-8 / SiO2 composite powder is obtained by surface grafting modification of ZIF-8 / SiO2 with a silane coupling agent. The content of modified ZIF-8 / SiO2 composite powder in the second coating layer is less than that in the third coating layer. The content of polydimethylsiloxane in the second coating layer is less than that in the third coating layer. The content of epoxy resin in the second coating layer is greater than that in the third coating layer.

[0017] In an optional embodiment of the present invention, the wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating satisfies the following conditional expression:

[0018] A:B = 1:(0.1-3)

[0019] Wherein, A represents the sum of the total mass of epoxy resin and the total mass of polydimethylsiloxane in the wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating, and B represents the total mass of the modified ZIF-8 / SiO2 composite powder in the wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating.

[0020] In the modified ZIF-8 / SiO2 composite powder, the mass ratio of ZIF-8 powder to tetraethyl silicate is 1:(0.1-10).

[0021] In an optional embodiment of the present invention, the silane coupling agent is selected from at least one of KH550, KH560, KH570, KH590, octyltriethoxysilane, dodecyltrimethoxysilane, and hexadecyltrimethoxysilane.

[0022] Another aspect of the present invention provides a method for preparing the above-mentioned wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating, comprising:

[0023] S1, Preparation of ZIF-8, a zeolite-like imidazole framework material;

[0024] S2, modified ZIF-8 / SiO2 composite powder was obtained by grafting ZIF-8 with in-situ grown SiO2 on the surface using a silane coupling agent.

[0025] S3. The modified ZIF-8 / SiO2 composite powder is mixed with polydimethylsiloxane and epoxy resin in the corresponding proportions and then coated onto the metal substrate in sequence to obtain the wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating.

[0026] In an optional embodiment of the present invention, the preparation process of the modified ZIF-8 / SiO2 composite powder includes: mixing ZIF-8 powder with a solvent evenly, then adding tetraethyl silicate and a silane coupling agent, stirring at room temperature for 4-24 hours, and obtaining the modified ZIF-8 / SiO2 composite powder after centrifugation, washing and drying.

[0027] In an optional embodiment of the present invention, the solvent is selected from at least one of methanol, ethanol, isopropanol, toluene, acetone, cyclohexane, and butyl acetate;

[0028] The amount of solvent used per gram of the ZIF-8 powder is 20 mL to 600 mL;

[0029] The mass ratio of ZIF-8 powder to silane coupling agent is 1:(0.1-5.0);

[0030] In the process of preparing modified ZIF-8 / SiO2 composite powder, an alkaline solution was added to control the pH value of the reaction system to 9-11;

[0031] The solvent used for centrifugal cleaning is at least one of deionized water, methanol, ethanol, isopropanol, toluene, acetone, and cyclohexane.

[0032] In an optional embodiment of the present invention, ZIF-8 powder is prepared by co-precipitation method;

[0033] The preparation process of ZIF-8 powder includes: preparing two transparent solutions, zinc nitrate hexahydrate and 2-methylimidazole, in methanol respectively; then pouring the zinc nitrate hexahydrate solution into the 2-methylimidazole solution; stirring the mixed solution at room temperature for 1-24 hours; and then centrifuging, washing and drying to obtain ZIF-8 powder.

[0034] In an optional embodiment of the present invention, the molar ratio of zinc nitrate hexahydrate to 2-methylimidazole is 1:(4-70);

[0035] The mixed solution is centrifuged and washed using at least one of deionized water, methanol, ethanol, isopropanol, toluene, acetone, and cyclohexane.

[0036] In an optional embodiment of the present invention, step S3 specifically includes:

[0037] After the modified ZIF-8 / SiO2 composite powder is mixed with polydimethylsiloxane and epoxy resin and diluent in the appropriate proportion, a first coating layer, a second coating layer, and a third coating layer are obtained. Then, the first coating layer, the second coating layer, and the third coating layer are sequentially coated on the metal substrate.

[0038] The diluent is selected from at least one of toluene, isopropanol, acetone, cyclohexane, n-hexane, ethyl acetate, butyl acetate, and acetaldehyde.

[0039] In an optional embodiment of the present invention, the coating method is selected from at least one of spraying, spin coating, scraping, roller coating and brush coating.

[0040] Another aspect of the present invention provides the application of the above-mentioned wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating in the preparation of anti-corrosion coatings for offshore wind power projects.

[0041] The embodiments of the present invention will be further described below with reference to several examples. The embodiments of the present invention are not limited to the specific embodiments described below. Appropriate modifications can be made within the scope of unchanged main claims.

[0042] Example 1

[0043] This embodiment provides a wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating and its preparation method. The gradient composite coating includes a first coating layer, a second coating layer, and a third coating layer sequentially coated on a metal substrate. The first coating layer comprises 0.9g epoxy resin, 0.1g PDMS, and 0.1g modified ZIF-8 / SiO2 composite powder; the second coating layer comprises 0.8g epoxy resin, 0.2g PDMS, and 0.3g modified ZIF-8 / SiO2 composite powder; and the third coating layer comprises 0.7g epoxy resin, 0.3g PDMS, and 0.5g modified ZIF-8 / SiO2 composite powder.

[0044] The preparation method includes:

[0045] (1) Preparation of ZIF-8 powder

[0046] 3.96 g of zinc nitrate hexahydrate and 4.11 g of 2-methylimidazole were weighed and dispersed in 100 mL of methanol. The mixture was sonicated for half an hour to obtain two transparent solutions. Then, the zinc nitrate hexahydrate solution was slowly added to the 2-methylimidazole solution. The mixture was mechanically stirred at room temperature for 24 h. The mixture was centrifuged at 8000 rpm for 5 min and washed three times with methanol. The mixture was then dried in a vacuum oven at 80 °C for 12 h to obtain ZIF-8 powder.

[0047] (2) Preparation of modified ZIF-8 / SiO2 composite powder

[0048] Weigh 0.5g of ZIF-8 powder and dissolve it in 200mL of ethanol. Then add 5mL of ammonia and 5mL of deionized water to the mixed solution. After stirring for 20min, add 2g of TEOS (tetraethyl silicate) and 1g of hexadecyltrimethoxysilane. Stir at room temperature for 24h, then add 5mL of acetic acid. After washing three times with ethanol by centrifugation, dry in a vacuum oven at 80℃ for 12h to obtain modified ZIF-8 / SiO2 composite powder.

[0049] (3) Preparation of wear-resistant and corrosion-resistant superhydrophobic gradient composite coating

[0050] Mix the components of the first, second, and third coating layers according to their respective proportions, and after thorough mixing, spray them sequentially onto the tinplate substrate.

[0051] Specifically, 0.9g of epoxy resin, 0.1g of PDMS main agent and 0.1g of modified ZIF-8 / SiO2 composite powder are dissolved in 10mL of butyl acetate. After ultrasonic treatment for 10min, 0.18g of epoxy curing agent and 0.01g of PDMS curing agent are added and ultrasonically treated for 5min. The mixed solution is then sprayed onto the tinplate substrate as the first coating layer. After curing at room temperature for 10min, the second coating layer is sprayed.

[0052] Dissolve 0.8g epoxy resin, 0.2g PDMS main agent and 0.3g modified ZIF-8 / SiO2 composite powder in 10mL butyl acetate. After ultrasonic treatment for 10min, add 0.16g epoxy curing agent and 0.02g PDMS curing agent, ultrasonic treatment for 5min, and then spray the mixed solution onto the first coating layer. After curing at room temperature for 10min, spray the third coating layer.

[0053] Dissolve 0.7g epoxy resin, 0.3g PDMS main agent and 0.5g modified ZIF-8 / SiO2 composite powder in 10mL butyl acetate. After ultrasonic treatment for 10min, add 0.14g epoxy curing agent and 0.03g PDMS curing agent, ultrasonic treatment for 5min, then spray the mixed solution onto the second coating layer, and then place it in a 120℃ oven for high-temperature curing for 3h to obtain a wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating.

[0054] Example 2

[0055] This embodiment provides a wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating and its preparation method. The gradient composite coating includes a first coating layer, a second coating layer, and a third coating layer sequentially coated on a metal substrate. The first coating layer comprises 0.9g epoxy resin, 0.1g PDMS, and 0.3g modified ZIF-8 / SiO2 composite powder; the second coating layer comprises 0.8g epoxy resin, 0.2g PDMS, and 0.5g modified ZIF-8 / SiO2 composite powder; and the third coating layer comprises 0.7g epoxy resin, 0.3g PDMS, and 0.7g modified ZIF-8 / SiO2 composite powder.

[0056] The preparation method includes:

[0057] (1) Preparation of ZIF-8 powder

[0058] 3.96 g of zinc nitrate hexahydrate and 4.11 g of 2-methylimidazole were weighed and dispersed in 100 mL of methanol. The mixture was sonicated for half an hour to obtain two transparent solutions. Then, the zinc nitrate hexahydrate solution was slowly added to the 2-methylimidazole solution. The mixture was mechanically stirred at room temperature for 24 h. The mixture was centrifuged at 8000 rpm for 5 min and washed three times with methanol. The mixture was then dried in a vacuum oven at 80 °C for 12 h to obtain ZIF-8 powder.

[0059] (2) Preparation of modified ZIF-8 / SiO2 composite powder

[0060] Weigh 0.5g of ZIF-8 powder and dissolve it in 200mL of ethanol. Then add 5mL of ammonia and 5mL of deionized water to the mixed solution. After stirring for 20min, add 2g of TEOS and 1g of hexadecyltrimethoxysilane. Stir at room temperature for 24h and then add 5mL of acetic acid. After washing three times with ethanol by centrifugation, dry in a vacuum oven at 80℃ for 12h to obtain modified ZIF-8 / SiO2 composite powder.

[0061] (3) Preparation of wear-resistant and corrosion-resistant superhydrophobic gradient composite coating

[0062] Specifically, the components of the first, second, and third coating layers are mixed in the specified proportions, and after being thoroughly stirred, they are sequentially sprayed onto the tinplate substrate.

[0063] Dissolve 0.9g epoxy resin, 0.1g PDMS main agent and 0.3g modified ZIF-8 / SiO2 composite powder in 10mL butyl acetate. After ultrasonic treatment for 10min, add 0.18g epoxy curing agent and 0.01g PDMS curing agent, ultrasonic treatment for 5min, and then spray the mixed solution onto the tinplate substrate as the first coating layer. After curing at room temperature for 10min, spray the second coating layer.

[0064] Dissolve 0.8g epoxy resin, 0.2g PDMS main agent and 0.5g modified ZIF-8 / SiO2 composite powder in 10mL butyl acetate. After ultrasonic treatment for 10min, add 0.16g epoxy curing agent and 0.02g PDMS curing agent, ultrasonic treatment for 5min, and then spray the mixed solution onto the first coating layer. After curing at room temperature for 10min, spray the third coating layer.

[0065] Dissolve 0.7g epoxy resin, 0.3g PDMS main agent and 0.7g modified ZIF-8 / SiO2 composite powder in 10mL butyl acetate. After ultrasonic treatment for 10min, add 0.14g epoxy curing agent and 0.03g PDMS curing agent, ultrasonic treatment for 5min, then spray the mixed solution onto the second coating layer, and then place it in a 120℃ oven for high-temperature curing for 3h to obtain a wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating.

[0066] Example 3

[0067] This embodiment provides a wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating and its preparation method. The gradient composite coating includes a first coating layer, a second coating layer, and a third coating layer sequentially coated on a metal substrate. The first coating layer comprises 0.9g epoxy resin, 0.1g PDMS, and 0.5g modified ZIF-8 / SiO2 composite powder; the second coating layer comprises 0.8g epoxy resin, 0.2g PDMS, and 0.7g modified ZIF-8 / SiO2 composite powder; and the third coating layer comprises 0.7g epoxy resin, 0.3g PDMS, and 0.9g modified ZIF-8 / SiO2 composite powder.

[0068] The preparation method includes:

[0069] (1) Preparation of ZIF-8 powder

[0070] 3.96 g of zinc nitrate hexahydrate and 4.11 g of 2-methylimidazole were weighed and dispersed in 100 mL of methanol. The mixture was sonicated for half an hour to obtain two transparent solutions. Then, the zinc nitrate hexahydrate solution was slowly added to the 2-methylimidazole solution. The mixture was mechanically stirred at room temperature for 24 h. The mixture was centrifuged at 8000 rpm for 5 min and washed three times with methanol. The mixture was then dried in a vacuum oven at 80 °C for 12 h to obtain ZIF-8 powder.

[0071] (2) Preparation of modified ZIF-8 / SiO2 composite powder

[0072] Weigh 0.5g of ZIF-8 powder and dissolve it in 200mL of ethanol. Then add 5mL of ammonia and 5mL of deionized water to the mixed solution. After stirring for 20min, add 2g of TEOS and 1g of hexadecyltrimethoxysilane. Stir at room temperature for 24h and then add 5mL of acetic acid. After washing three times with ethanol by centrifugation, dry in a vacuum oven at 80℃ for 12h to obtain modified ZIF-8 / SiO2 composite powder.

[0073] (3) Preparation of wear-resistant and corrosion-resistant superhydrophobic gradient composite coating

[0074] Mix the components of the first, second, and third coating layers according to their respective proportions, and after thorough mixing, spray them sequentially onto the tinplate substrate.

[0075] Specifically, 0.9g of epoxy resin, 0.1g of PDMS main agent and 0.5g of modified ZIF-8 / SiO2 are dissolved in 10mL of butyl acetate. After ultrasonic treatment for 10min, 0.18g of epoxy curing agent and 0.01g of PDMS curing agent are added, and ultrasonic treatment is carried out for 5min. The mixed solution is then sprayed onto the tinplate substrate as the first coating layer. After curing at room temperature for 10min, the second coating layer is sprayed.

[0076] Dissolve 0.8g epoxy resin, 0.2g PDMS main agent and 0.7g modified ZIF-8 / SiO2 composite powder in 10mL butyl acetate. After ultrasonic treatment for 10min, add 0.16g epoxy curing agent and 0.02g PDMS curing agent, ultrasonic treatment for 5min, and then spray the mixed solution onto the first coating layer. After curing at room temperature for 10min, spray the third coating layer.

[0077] Dissolve 0.7g epoxy resin, 0.3g PDMS main agent and 0.9g modified ZIF-8 / SiO2 composite powder in 10mL butyl acetate. After ultrasonic treatment for 10min, add 0.14g epoxy curing agent and 0.03g PDMS curing agent, ultrasonic treatment for 5min, then spray the mixed solution onto the second coating layer, and then place it in a 120℃ oven for high-temperature curing for 3h to obtain a wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating.

[0078] Comparative Example 1

[0079] The difference from Example 1 is that the first coating layer sprayed in step (3) does not contain modified ZIF-8 / SiO2 composite powder.

[0080] Comparative Example 2

[0081] The difference from Example 1 is that the second coating layer sprayed in step (3) does not contain modified ZIF-8 / SiO2 composite powder.

[0082] Comparative Example 3

[0083] The difference from Example 1 is that the order of gradient composite coating spraying in step (3) is reversed, that is, the original bottom coating becomes the top coating, and the top coating becomes the bottom coating, while the position of the middle coating remains unchanged.

[0084] Experimental Example 1

[0085] The corrosion resistance performance of all embodiments and comparative examples was tested, and the results are shown in Table 1 and... Figure 1 As shown.

[0086] Corrosion resistance test: Electrochemical impedance spectroscopy (EIS) was performed using the Chenhua electrochemical workstation. After the test, the data was fitted using ZView impedance fitting software to obtain various electrochemical performance parameters.

[0087] Corrosion inhibition rate (η) z The calculation formula for %) is as follows:

[0088]

[0089] In the formula: R ct The charge transfer resistance of tinplate sheets coated with gradient composite coatings of different component contents in a 3.5 wt% NaCl corrosion solution;

[0090] R ct 0 This represents the charge transfer resistance of the epoxy coating control group.

[0091] Table 1

[0092]

[0093] As can be seen from Table 1, all embodiments exhibit excellent corrosion resistance, with Embodiment 1 showing the best corrosion resistance. Among the three comparative examples set with Embodiment 1 as a reference, Comparative Example 3 was applied in the reverse order of the original gradient composite coating, while Comparative Examples 1 and 2 lacked the modified ZIF-8 / SiO2 composite powder in the bottom and middle adhesive layers of the original gradient composite coating, respectively. Since none of the three comparative examples could form the same gradient composite coating structure as Embodiment 1, the degree of cross-linking within the coating decreased, leading to a decline in their corrosion resistance.

[0094] Experimental Example 2

[0095] The wear resistance properties of all embodiments and comparative examples were tested, and the results are shown in Table 2 and... Figure 2 As shown.

[0096] Wear resistance test method: Press a 100g weight onto the sample and drag it 20cm on 800 mesh paper with 3M tape as one cycle. Record the contact angle every 5 cycles. The table below records the contact angle of the sample after different wear cycles of the coating.

[0097] Table 2. Statistical Table of Wear Resistance Tests

[0098]

[0099] As shown in Table 2, the gradient composite coatings obtained in Examples 1 to 3 all exhibited superior wear resistance, with Example 1 showing the best wear resistance. The wear resistance of Example 1 was superior to that of the three comparative examples because none of the comparative examples formed a highly cross-linked gradient composite coating structure. Among the comparative examples, Comparative Examples 1 and 2 showed significantly better wear resistance than Comparative Example 3. This is because after the top hydrophobic layer wore down, the modified composite micro / nanoparticles were exposed in the middle adhesive layer and the bottom coating, increasing surface roughness and thus maintaining long-term superhydrophobic properties. Comparative Example 3, due to the lower content of modified composite powder in its top coating, did not initially show a high contact angle in the wear resistance test. However, after the top coating wore down, the modified composite micro / nanoparticles were exposed, increasing surface roughness and slightly improving the contact angle. However, due to insufficient adhesion between the bottom coating and the tinplate substrate, the contact angle decreased significantly after multiple wear cycles.

[0100] In summary, the wear-resistant, corrosion-resistant, superhydrophobic gradient composite coating, its preparation method, and its application provided by the present invention have the following beneficial effects:

[0101] This invention presents a gradient composite coating that combines wear resistance, corrosion resistance, and superhydrophobicity, based on a modified ZIF-8 / SiO2 composite powder, an organosilicon polymer PDMS (polydimethylsiloxane), and a high-molecular-weight epoxy resin. The performance of the functionalized gradient composite coating is controlled by adjusting the proportions of each component during the preparation of each coating layer. From the side closer to the metal substrate to the side farther away, gradually increasing the proportions of the modified ZIF-8 / SiO2 composite powder and the organosilicon polymer PDMS in each coating layer gradually enhances the hydrophobicity of the coating surface. Conversely, from the side farther away from the metal substrate to the side closer to the metal substrate, gradually increasing the proportions of the high-molecular-weight epoxy resin in each coating layer gradually enhances the adhesion of the coating. Compared to traditional single protective coatings, this gradient composite coating exhibits excellent superhydrophobic properties while simultaneously improving its density, stability, wear resistance, and corrosion resistance.

[0102] Furthermore, the preparation method of the wear-resistant and corrosion-resistant superhydrophobic gradient composite coating provided by this invention has a simple process flow, mild reaction conditions, low energy consumption, and is suitable for large-scale production. It is of great significance for the research on developing multifunctional protective coatings for offshore wind power projects.

[0103] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the scope of protection of the present invention. Therefore, the scope of protection of this patent should be determined by the appended claims.

Claims

1. A wear resistant, corrosion resistant, superhydrophobic gradient composite coating, characterized in that, The coating includes a first layer, a second layer and a third layer coated on a metal substrate in sequence, the first layer coating includes modified ZIF-8 / SiO2 composite powder, polydimethylsiloxane and epoxy resin, the second layer coating includes modified ZIF-8 / SiO2 composite powder, polydimethylsiloxane and epoxy resin, and the third layer coating includes modified ZIF-8 / SiO2 composite powder, polydimethylsiloxane and epoxy resin, the preparation process of the modified ZIF-8 / SiO2 composite powder includes: uniformly mixing ZIF-8 powder with a solvent, then adding tetraethyl orthosilicate and silane coupling agent, stirring at room temperature for 4-24 hours, and then centrifugally washing and drying to obtain the modified ZIF-8 / SiO2 composite powder; wherein, from the side close to the metal substrate to the side away from the metal substrate, the proportion of the modified ZIF-8 / SiO2 composite powder and polydimethylsiloxane in each coating is gradually increased; from the side away from the metal substrate to the side close to the metal substrate, the proportion of the epoxy resin in each coating is gradually increased.

2. The wear resistant, corrosion resistant, superhydrophobic gradient composite coating according to claim 1, wherein, The wear-resistant and corrosion-resistant super-hydrophobic gradient composite coating satisfies the following conditional formula: A:B = 1: (0.1-3) Wherein, A represents the sum of the total mass of the epoxy resin and the total mass of the polydimethylsiloxane in the wear-resistant and corrosion-resistant super-hydrophobic gradient composite coating, and B represents the total mass of the modified ZIF-8 / SiO2 composite powder in the wear-resistant and corrosion-resistant super-hydrophobic gradient composite coating. In the modified ZIF-8 / SiO2 composite powder, the mass ratio of the ZIF-8 powder to the tetraethyl orthosilicate is 1: (0.1-10).

3. The wear resistant, corrosion resistant, superhydrophobic gradient composite coating of claim 1, wherein, The silane coupling agent is at least one selected from KH550, KH560, KH570, KH590, octyl triethoxysilane, dodecyl trimethoxysilane and hexadecyl trimethoxysilane.

4. The method of producing a wear resistant, corrosion resistant, superhydrophobic gradient composite coating according to any one of claims 1 to 3, characterized in that, It includes: S1, preparation of ZIF-8 powder; S2, uniformly mixing the ZIF-8 powder with a solvent, then adding tetraethyl orthosilicate and silane coupling agent, stirring at room temperature for 4-24 hours, and then centrifugally washing and drying to obtain the modified ZIF-8 / SiO2 composite powder; S3, mixing the modified ZIF-8 / SiO2 composite powder with polydimethylsiloxane and epoxy resin according to the corresponding proportion, and then coating on the metal substrate in sequence to obtain the wear-resistant and corrosion-resistant super-hydrophobic gradient composite coating.

5. The preparation method according to claim 4, characterized in that, The solvent is at least one selected from methanol, ethanol, isopropanol, toluene, acetone, cyclohexane and butyl acetate; The amount of the solvent corresponding to each gram of the ZIF-8 powder is 20 mL-600 mL; The mass ratio of the ZIF-8 powder to the silane coupling agent is 1: (0.1-5.0); In the process of preparing the modified ZIF-8 / SiO2 composite powder, an alkaline solution is added, and the pH value of the reaction system is controlled to be 9-11; The solvent used for centrifugal washing is at least one selected from deionized water, methanol, ethanol, isopropanol, toluene, acetone and cyclohexane.

6. The production method according to claim 5, wherein The ZIF-8 powder is prepared by a co-precipitation method. The preparation process of the ZIF-8 powder comprises: preparing two transparent solutions of zinc nitrate hexahydrate and 2-methylimidazole respectively in methanol, then pouring the zinc nitrate hexahydrate solution into the 2-methylimidazole solution, and after stirring the mixed solution at room temperature for 1 h-24 h, centrifuging, washing and drying to obtain the ZIF-8 powder.

7. The preparation method of claim 6, wherein: The molar ratio of zinc nitrate hexahydrate to 2-methylimidazole is 1:(4-70); The washing in the preparation process of the ZIF-8 powder uses at least one of deionized water, methanol, ethanol, isopropanol, toluene, acetone and cyclohexane.

8. The production method according to claim 7, characterized by, Step S3 specifically comprises: The modified ZIF-8 / SiO2 composite powder is mixed with polydimethylsiloxane and epoxy resin according to the corresponding proportions and diluents to obtain a first layer of coating, a second layer of coating and a third layer of coating, and then the first layer of coating, the second layer of coating and the third layer of coating are sequentially coated on the metal substrate. The diluent is selected from at least one of toluene, isopropanol, acetone, cyclohexane, n-hexane, ethyl acetate and butyl acetate.

9. Use of the wear-resistant and corrosion-resistant super-hydrophobic gradient composite coating according to any one of claims 1-3 in the preparation of a corrosion-resistant coating for offshore wind power engineering.

Images