High-corrosion-resistance and long-service-life hydrophobic coating for offshore photovoltaic support and preparation method of high-corrosion-resistance and long-service-life hydrophobic coating

Abstract

The invention discloses a hydrophobic coating with high corrosion resistance and long service life for an offshore photovoltaic support and a preparation method of the hydrophobic coating, and belongs to the technical field of surface protection of the offshore photovoltaic support. The concrete is prepared by mixing the following raw material components in parts by weight: 100 parts of a silicon-aluminum ingredient, 10-30 parts of an alkali activator, 1-2 parts of a water reducing agent, 0.3-1 part of a water-soluble polymer, 1-5 parts of an expanding agent, 0.5-2 parts of a surface modifier and 40-60 parts of water. According to the invention, corrosion ions in the marine environment are effectively prevented from invading, efficient protection of the offshore photovoltaic support and prolonging of the service life are realized, and the later maintenance cost is reduced.

Description

Technical Field

[0001] The present invention relates to a highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic bracket and a preparation method thereof, belonging to the technical field of surface protection of offshore photovoltaic brackets. Background Art

[0002] Offshore photovoltaics (PV) are a rapidly growing renewable energy source in recent years. However, due to the harsh and complex operating environment, PV mounting systems are often subject to corrosion from salt ions, temperature and humidity fluctuations, and wave erosion. Under these conditions, traditional steel mounting systems are highly susceptible to corrosion, leading to component failure, significantly shortening the mounting's service life and causing significant economic losses.

[0003] In actual engineering construction, coatings are usually used to improve the corrosion resistance of steel supports in marine environments. Common coatings include hot-dip galvanizing, zinc-aluminum-magnesium coatings, and spray anti-corrosion coatings.

[0004] Among them, the existing anti-corrosion coatings are mainly epoxy resin system coatings. This type of coating has high chemical stability, good protective performance and strong adhesion, but it also has problems such as poor weather resistance and many restrictions on curing conditions.

[0005] Therefore, the development of new coatings with high corrosion resistance and long life for offshore photovoltaic brackets is crucial to achieve bracket protection, performance maintenance and service life extension. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a highly corrosion-resistant, long-life hydrophobic coating for offshore photovoltaic brackets and a preparation method thereof, which solves the problem in the prior art that offshore photovoltaic brackets are easily corroded, which leads to component failure, seriously shortens the service life of the brackets, and causes huge economic losses.

[0007] The present invention proposes a highly corrosion-resistant and long-life hydrophobic coating for offshore photovoltaic brackets. The raw materials of the coating include 100 parts of silicon-aluminum ingredients, 10 to 30 parts of alkali activator, 1 to 2 parts of water reducer, 0.3 to 1 part of water-soluble polymer, 1 to 5 parts of expansion agent, 0.5 to 2 parts of surface modifier and 40 to 60 parts of water.

[0008] Furthermore, the siliceous-aluminous ingredient is any one of metakaolin, tuff, fly ash or mineral powder, or a mixture of two or more of them in any proportion.

[0009] Furthermore, the alkaline activator is any one of sodium hydroxide, sodium silicate or sodium carbonate.

[0010] Furthermore, the water reducer is a polycarboxylate water reducer.

[0011] Furthermore, the surface modifier is any one of silane, siloxane or fluorosilane.

[0012] Furthermore, the water-soluble polymer is any one of carboxyethyl cellulose ether, carboxymethyl cellulose ether or carboxyethyl methyl cellulose ether.

[0013] Furthermore, the expansion agent is any one of a MgO-based expansion agent and a CaO-based expansion agent.

[0014] A method for preparing a highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support comprises the following steps: 1) First, dissolve 0.3-1 parts of water-soluble polymer in water in advance and set aside; 2) Then, 100 parts of the silicon-aluminum ingredient, 1-2 parts of a water reducer, and 1-5 parts of an expansion agent were mixed and stirred at a low speed of 140 rpm using a JJ-5 mixer to uniformly mix the mixture; 3) Then, 10-30 parts of an alkali activator and 40-60 parts of water are added to the mixture and stirred at a low speed of 140 rpm to obtain a fresh slurry; 4) Finally, 0.5-2 parts of surface modifier was added to the fresh slurry and stirred at 285 rpm to obtain a hydrophobic coating.

[0015] The beneficial effects of the present invention are: (1) The highly corrosion-resistant and long-life hydrophobic coating for the offshore photovoltaic bracket of the present invention uses siliceous and aluminous ingredients such as metakaolin, tuff, fly ash or mineral powder as precursors. The raw materials are mostly solid waste or industrial by-products, which are abundant in source and low in cost, and have good economic and environmental benefits.

[0016] (2) Surface modifiers, water-soluble polymers and expansion agents are used to synergistically modify the coating performance. Specifically, the surface energy of the coating is modified by the surface modifier to construct a hydrophobic system; water-soluble polymers are introduced to optimize the working performance of the coating and improve the sprayability and brushability of the coating; based on the expansion modification effect of the expansion agent, the shrinkage behavior of the coating is alleviated and the adhesion of the coating is improved.

[0017] (3) The preparation method of the present application is simple and easy to operate. At the same time, the hydrophobic coating prepared by this method has excellent bonding and durability, effectively blocking the invasion of corrosive ions in the marine environment, achieving efficient protection of offshore photovoltaic brackets and extending their service life, thereby reducing subsequent maintenance costs. DETAILED DESCRIPTION

[0018] In order to facilitate a clear understanding of the technical means, creative features, objectives and effects of the present invention, the present invention is further described below.

[0019] A highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support is prepared by mixing the following raw material components in parts by weight: 100 parts of a silicon-aluminum batching, 10-30 parts of an alkali activator, 1-2 parts of a water reducer, 0.3-1 parts of a water-soluble polymer, 1-5 parts of an expansion agent, 0.5-2 parts of a surface modifier, and 40-60 parts of water.

[0020] The siliceous-aluminous ingredient is any one of metakaolin, tuff, fly ash or mineral powder, or a mixture of two or more of them in any proportion; The alkaline activator is any one of sodium hydroxide, sodium silicate or sodium carbonate; The water reducer is a polycarboxylate water reducer; The surface modifier is any one of silane, siloxane or fluorosilane; The water-soluble polymer is any one of carboxyethyl cellulose ether, carboxymethyl cellulose ether or carboxyethyl methyl cellulose ether; The expansion agent is any one of a MgO-based expansion agent and a CaO-based expansion agent.

[0021] The preparation method comprises the following steps: 1) First, dissolve 0.3-1 parts of water-soluble polymer in water in advance and set aside; 2) Then, 100 parts of the silicon-aluminum ingredient, 1-2 parts of a water reducer, and 1-5 parts of an expansion agent were mixed and stirred at a low speed of 140 rpm using a JJ-5 mixer to uniformly mix the mixture; 3) Then, 10-30 parts of an alkali activator and 40-60 parts of water are added to the mixture and stirred at a low speed of 140 rpm to obtain a fresh slurry; 4) Finally, 0.5-2 parts of surface modifier was added to the fresh slurry and stirred at 285 rpm to obtain a hydrophobic coating.

[0022] Hydrophobic coating based on the above setup: On the one hand, the precursors are siliceous and aluminous ingredients such as metakaolin, tuff, fly ash or mineral powder. The raw materials are mostly solid waste or industrial by-products, which are abundant in source and low in cost, and have good economic and environmental benefits. On the other hand, surface modifiers, water-soluble polymers and expansion agents are used to synergistically modify the coating properties. Specifically, surface modifiers are used to modify the coating surface to construct a hydrophobic system; water-soluble polymers are introduced to optimize the coating's performance and improve its sprayability and brushability; based on the expansion modification effect of the expansion agent, the shrinkage behavior of the coating is alleviated and the adhesion of the coating is improved; In addition, the preparation method of the present application is simple and easy to operate. At the same time, the hydrophobic coating prepared by this method has excellent bonding and durability, effectively blocking the invasion of corrosive ions in the marine environment, achieving efficient protection of offshore photovoltaic brackets and extending their service life, thereby reducing subsequent maintenance costs.

[0023] Example 1 A highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support comprises the following components by weight: 80 parts of metakaolin, 20 parts of tuff, 20 parts of an alkali activator, 1 part of a water reducer, 2 parts of a surface modifier, 1 part of a water-soluble polymer, 3 parts of an expander, and 55 parts of water.

[0024] The preparation method is as follows: 1) First, fully dissolve 1 part of water-soluble polymer in water in advance and set aside; 2) Subsequently, 80 parts of metakaolin, 20 parts of tuff, 1 part of water reducer and 3 parts of expansion agent were mixed and stirred at a low speed of 140 rpm using a JJ-5 mixer to uniformly mix the mixture; 3) Then, 20 parts of alkali activator and 55 parts of water were added to the mixture and stirred at a low speed of 140 rpm to obtain a fresh slurry; 4) Finally, 2 parts of the surface modifier were added to the fresh slurry and stirred at 285 rpm to obtain a hydrophobic coating.

[0025] Usage: Apply the hydrophobic coating to the surface of the photovoltaic bracket by brushing, spraying, etc., with a coating thickness of 3~5mm. After initial curing at 20±2℃ and 95%±3% relative humidity, a hardened hydrophobic coating is obtained.

[0026] Example 2 A highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support, comprising the following components by weight: 80 parts of metakaolin, 20 parts of fly ash, 20 parts of an alkali activator, 1 part of a water reducer, 2 parts of a surface modifier, 1 part of a water-soluble polymer, 3 parts of an expansion agent, and 55 parts of water.

[0027] The preparation method is as follows: 1) First, fully dissolve 1 part of water-soluble polymer in water in advance and set aside; 2) Subsequently, 80 parts of metakaolin, 20 parts of fly ash, 1 part of water reducer and 3 parts of expansion agent were mixed and stirred at a low speed of 140 rpm using a JJ-5 mixer to uniformly mix the mixture; 3) Then, 20 parts of alkali activator and 55 parts of water were added to the mixture and stirred at a low speed of 140 rpm to obtain a fresh slurry; 4) Finally, 2 parts of the surface modifier were added to the fresh slurry and stirred at 285 rpm to obtain a hydrophobic coating.

[0028] Usage: Apply the hydrophobic coating to the surface of the photovoltaic bracket by brushing, spraying, etc., with a coating thickness of 3~5mm. After initial curing at 20±2℃ and 95%±3% relative humidity, a hardened hydrophobic coating is obtained.

[0029] Example 3 A highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support, comprising the following components by weight: 80 parts of metakaolin, 20 parts of mineral powder, 20 parts of an alkali activator, 1 part of a water reducer, 2 parts of a surface modifier, 1 part of a water-soluble polymer, 3 parts of an expander, and 55 parts of water.

[0030] The preparation method is as follows: 1) First, fully dissolve 1 part of water-soluble polymer in water in advance and set aside; 2) Subsequently, 80 parts of metakaolin, 20 parts of mineral powder, 1 part of water reducer, and 3 parts of expansion agent were mixed and stirred at a low speed of 140 rpm using a JJ-5 mixer to uniformly mix the mixture; 3) Then, 20 parts of alkali activator and 55 parts of water were added to the mixture and stirred at a low speed of 140 rpm to obtain a fresh slurry; 4) Finally, 2 parts of the surface modifier were added to the fresh slurry and stirred at 285 rpm to obtain a hydrophobic coating.

[0031] Usage: Apply the hydrophobic coating to the surface of the photovoltaic bracket by brushing, spraying, etc., with a coating thickness of 3~5mm. After initial curing at 20±2℃ and 95%±3% relative humidity, a hardened hydrophobic coating is obtained.

[0032] Example 4 A highly corrosion-resistant, long-life hydrophobic coating for an offshore photovoltaic support, comprising the following components by weight: 70 parts of mineral powder, 30 parts of fly ash, 20 parts of an alkali activator, 1 part of a water reducer, 2 parts of a surface modifier, 1 part of a water-soluble polymer, 3 parts of an expansion agent, and 55 parts of water.

[0033] The preparation method is as follows: 1) First, fully dissolve 1 part of water-soluble polymer in water in advance and set aside; 2) Subsequently, 70 parts of metakaolin, 30 parts of tuff, 1 part of water reducer and 3 parts of expansion agent were mixed and stirred at a low speed of 140 rpm using a JJ-5 mixer to uniformly mix the mixture; 3) Then, 20 parts of alkali activator and 55 parts of water were added to the mixture and stirred at a low speed of 140 rpm to obtain a fresh slurry; 4) Finally, 2 parts of the surface modifier were added to the fresh slurry and stirred at 285 rpm to obtain a hydrophobic coating.

[0034] Usage: Apply the hydrophobic coating to the surface of the photovoltaic bracket by brushing, spraying, etc., with a coating thickness of 3~5mm. After initial curing at 20±2℃ and 95%±3% relative humidity, a hardened hydrophobic coating is obtained.

[0035] Example 5 A highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support, comprising the following components by weight: 70 parts of mineral powder, 30 parts of tuff, 20 parts of an alkali activator, 1 part of a water reducer, 2 parts of a surface modifier, 1 part of a water-soluble polymer, 3 parts of an expander, and 55 parts of water.

[0036] The preparation method is as follows: 1) First, fully dissolve 1 part of water-soluble polymer in water in advance and set aside; 2) Subsequently, 70 parts of mineral powder, 30 parts of tuff, 1 part of water reducer and 3 parts of expansion agent were mixed and stirred at a low speed of 140 rpm using a JJ-5 mixer to uniformly mix the mixture; 3) Then, 20 parts of alkali activator and 55 parts of water were added to the mixture and stirred at a low speed of 140 rpm to obtain a fresh slurry; 4) Finally, 2 parts of the surface modifier were added to the fresh slurry and stirred at 285 rpm to obtain a hydrophobic coating.

[0037] Usage: Apply the hydrophobic coating to the surface of the photovoltaic bracket by brushing, spraying, etc., with a coating thickness of 3~5mm. After initial curing at 20±2℃ and 95%±3% relative humidity, a hardened hydrophobic coating is obtained.

[0038] Example 6 A highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support, comprising the following components by weight: 50 parts fly ash, 50 parts tuff, 20 parts alkali activator, 1 part water reducer, 2 parts surface modifier, 1 part water-soluble polymer, 3 parts expansion agent, and 55 parts water.

[0039] The preparation method is as follows: 1) First, fully dissolve 1 part of water-soluble polymer in water in advance and set aside; 2) Subsequently, 50 parts of fly ash, 50 parts of tuff, 1 part of water reducer and 3 parts of expansion agent were mixed and stirred at a low speed of 140 rpm using a JJ-5 mixer to uniformly mix the mixture; 3) Then, 20 parts of alkali activator and 55 parts of water were added to the mixture and stirred at a low speed of 140 rpm to obtain a fresh slurry; 4) Finally, 2 parts of the surface modifier were added to the fresh slurry and stirred at 285 rpm to obtain a hydrophobic coating.

[0040] Usage: Apply the hydrophobic coating to the surface of the photovoltaic bracket by brushing, spraying, etc., with a coating thickness of 3~5mm. After initial curing at 20±2℃ and 95%±3% relative humidity, a hardened hydrophobic coating is obtained.

[0041] Example 7 A highly corrosion-resistant, long-life hydrophobic coating for an offshore photovoltaic support, comprising the following components by weight: 50 parts of mineral powder, 20 parts of metakaolin, 30 parts of fly ash, 20 parts of an alkali activator, 1 part of a water reducer, 2 parts of a surface modifier, 1 part of a water-soluble polymer, 3 parts of an expansion agent, and 55 parts of water.

[0042] The preparation method is as follows: 1) First, fully dissolve 1 part of water-soluble polymer in water in advance and set aside; 2) Subsequently, 50 parts of mineral powder, 20 parts of metakaolin, 30 parts of fly ash, 1 part of water reducer and 3 parts of expansion agent were mixed and stirred at a low speed of 140 rpm using a JJ-5 mixer to uniformly mix the mixture; 3) Then, 20 parts of alkali activator and 55 parts of water were added to the mixture and stirred at a low speed of 140 rpm to obtain a fresh slurry; 4) Finally, 2 parts of the surface modifier were added to the fresh slurry and stirred at 285 rpm to obtain a hydrophobic coating.

[0043] Usage: Apply the hydrophobic coating to the surface of the photovoltaic bracket by brushing, spraying, etc., with a coating thickness of 3~5mm. After initial curing at 20±2℃ and 95%±3% relative humidity, a hardened hydrophobic coating is obtained.

[0044] Example 8 A highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support, comprising the following components by weight: 50 parts of mineral powder, 20 parts of metakaolin, 30 parts of tuff, 20 parts of an alkali activator, 1 part of a water reducer, 2 parts of a surface modifier, 1 part of a water-soluble polymer, 3 parts of an expander, and 55 parts of water.

[0045] The preparation method is as follows: 1) First, fully dissolve 1 part of water-soluble polymer in water in advance and set aside; 2) Subsequently, 50 parts of mineral powder, 20 parts of metakaolin, 30 parts of tuff, 1 part of water reducer and 3 parts of expansion agent were mixed and stirred at a low speed of 140 rpm using a JJ-5 mixer to uniformly mix the mixture; 3) Then, 20 parts of alkali activator and 55 parts of water were added to the mixture and stirred at a low speed of 140 rpm to obtain a fresh slurry; 4) Finally, 2 parts of the surface modifier were added to the fresh slurry and stirred at 285 rpm to obtain a hydrophobic coating.

[0046] Usage: Apply the hydrophobic coating to the surface of the photovoltaic bracket by brushing, spraying, etc., with a coating thickness of 3~5mm. After initial curing at 20±2℃ and 95%±3% relative humidity, a hardened hydrophobic coating is obtained.

[0047] Example 9 A highly corrosion-resistant, long-life hydrophobic coating for an offshore photovoltaic support, comprising the following components by weight: 50 parts of mineral powder, 20 parts of fly ash, 30 parts of tuff, 20 parts of an alkali activator, 1 part of a water reducer, 2 parts of a surface modifier, 1 part of a water-soluble polymer, 3 parts of an expansion agent, and 55 parts of water.

[0048] The preparation method is as follows: 1) First, fully dissolve 1 part of water-soluble polymer in water in advance and set aside; 2) Subsequently, 50 parts of mineral powder, 20 parts of fly ash, 30 parts of tuff, 1 part of water reducer and 3 parts of expansion agent were mixed and stirred at a low speed of 140 rpm using a JJ-5 mixer to uniformly mix the mixture; 3) Then, 20 parts of alkali activator and 55 parts of water were added to the mixture and stirred at a low speed of 140 rpm to obtain a fresh slurry; 4) Finally, 2 parts of the surface modifier were added to the fresh slurry and stirred at 285 rpm to obtain a hydrophobic coating.

[0049] Usage: Apply the hydrophobic coating to the surface of the photovoltaic bracket by brushing, spraying, etc., with a coating thickness of 3~5mm. After initial curing at 20±2℃ and 95%±3% relative humidity, a hardened hydrophobic coating is obtained.

[0050] Example 10 A highly corrosion-resistant, long-life hydrophobic coating for offshore photovoltaic supports, comprising the following components by weight: 50 parts of metakaolin, 20 parts of fly ash, 30 parts of tuff, 20 parts of an alkali activator, 1 part of a water reducer, 2 parts of a surface modifier, 1 part of a water-soluble polymer, 3 parts of an expansion agent, and 55 parts of water.

[0051] The detailed preparation method is as follows: 1) First, fully dissolve 1 part of water-soluble polymer in water in advance and set aside; 2) Subsequently, 50 parts of metakaolin, 20 parts of fly ash, 30 parts of tuff, 1 part of water reducer and 3 parts of expansion agent were mixed and stirred at a low speed of 140 rpm using a JJ-5 mixer to uniformly mix the mixture; 3) Then, 20 parts of alkali activator and 55 parts of water were added to the mixture and stirred at a low speed of 140 rpm to obtain a fresh slurry; 4) Finally, 2 parts of the surface modifier were added to the fresh slurry and stirred at 285 rpm to obtain a hydrophobic coating.

[0052] Usage: Apply the hydrophobic coating to the surface of the photovoltaic bracket by brushing, spraying, etc., with a coating thickness of 3~5mm. After initial curing at 20±2℃ and 95%±3% relative humidity, a hardened hydrophobic coating is obtained.

[0053] The plastic viscosity, bonding strength, chloride ion diffusion resistance, sulfate corrosion resistance, and hydrophobicity of the hydrophobic coatings of Examples 1 to 10 were tested respectively. The results are shown in Table 1.

[0054] Table 1 Basic properties, anti-corrosion properties and hydrophobic properties of the coatings in the examples As shown in Table 1, the coating material prepared according to the method for preparing a highly corrosion-resistant, long-life hydrophobic coating material for offshore photovoltaic supports provided in an embodiment of the present invention exhibits considerable bonding ability, excellent corrosion resistance, and good hydrophobic properties. The plastic viscosity is determined by testing the hydrophobic coating, while the bonding strength, chloride ion diffusion coefficient, corrosion resistance, coating appearance, and contact angle are determined by testing the hardened hydrophobic coating.

[0055] Comparative Implementation Methods The following comparative examples are all set up based on the case with the best comprehensive performance among the above 10 cases, namely Example 4.

[0056] Comparative Example 1 The “surface modifier 2 parts” in Example 4 was replaced with “surface modifier 0 parts”, and the rest was the same as Example 4. The coating properties are shown in Table 2.

[0057] Comparative Example 2 The “surface modifier 2 parts” in Example 4 was replaced with “surface modifier 1 part”, and the rest was the same as Example 4. The coating properties are shown in Table 2.

[0058] Comparative Example 3 The “surface modifier 2 parts” in Example 4 was replaced with “surface modifier 3 parts”, and the rest was the same as Example 4. The coating properties are shown in Table 2.

[0059] Comparative Example 4 The “water-soluble polymer 1 part” in Example 4 was replaced with “water-soluble polymer 0 parts”, and the rest was the same as Example 4. The coating properties are shown in Table 2.

[0060] Comparative Example 5 The “1 part of water-soluble polymer” in Example 4 was replaced with “0.5 parts of water-soluble polymer”, and the rest was the same as Example 4. The coating properties are shown in Table 2.

[0061] Comparative Example 6 The “water-soluble polymer 1 part” in Example 4 was replaced with “water-soluble polymer 2 parts”, and the rest was the same as Example 4. The coating properties are shown in Table 2.

[0062] Comparative Example 7 The “3 parts of expansion agent” in Example 4 was replaced by “0 parts of expansion agent”, and the rest was the same as Example 4. The coating properties are shown in Table 2.

[0063] Comparative Example 8 The “3 parts of expansion agent” in Example 4 was replaced by “1 part of expansion agent”, and the rest was the same as Example 4. The coating properties are shown in Table 2.

[0064] Comparative Example 9 The “3 parts of expansion agent” in Example 4 was replaced by “5 parts of expansion agent”, and the rest was the same as Example 4. The coating properties are shown in Table 2.

[0065] Comparative Example 10 The "surface modifier 2 parts, water-soluble polymer 1 part, expander 3 parts" in Example 4 was replaced with "surface modifier 0 parts, water-soluble polymer 0 parts, expander 0 parts", and the rest was the same as Example 4. The coating properties are shown in Table 2.

[0066] Table 2 Basic properties, anti-corrosion properties and hydrophobic properties of comparative coatings It can be seen from comparative examples 1-10 in Table 2 that based on the preparation method of the highly corrosion-resistant and long-life hydrophobic coating for offshore photovoltaic supports provided by the present invention, the coordinated use of surface modifiers, water-soluble polymers, and expansion agents can prepare a coating material with excellent comprehensive performance.

[0067] Among them, the introduction of an appropriate amount of surface modifier can enhance the hydrophobic properties of the coating; water-soluble polymers can improve the adhesion ability of the coating; and the introduction of expansion agents can effectively alleviate the shrinkage behavior of the coating.

Claims

1. A highly corrosion-resistant, long-life hydrophobic coating for an offshore photovoltaic support, characterized by: The invention is prepared by mixing the following raw material components in parts by weight: 100 parts of silicon-aluminum ingredients, 10-30 parts of alkali activator, 1-2 parts of water reducer, 0.3-1 parts of water-soluble polymer, 1-5 parts of expansion agent, 0.5-2 parts of surface modifier and 40-60 parts of water.

2. The highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support according to claim 1, characterized in that: The silicon-alumina batching material is any one of metakaolin, tuff, fly ash or mineral powder, or a mixture of two or more of them in any proportion.

3. The highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support according to claim 1, characterized in that: The alkaline activator is any one of sodium hydroxide, sodium silicate or sodium carbonate.

4. The highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support according to claim 1, characterized in that: The water reducer is a polycarboxylate water reducer.

5. The highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support according to claim 1, characterized in that: The surface modifier is any one of silane, siloxane or fluorosilane.

6. The highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support according to claim 1, characterized in that: The water-soluble polymer is any one of carboxyethyl cellulose ether, carboxymethyl cellulose ether or carboxyethyl methyl cellulose ether.

7. The highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support according to claim 1, characterized in that: The expansion agent is any one of a MgO-based expansion agent and a CaO-based expansion agent.

8. A method for preparing the highly corrosion-resistant and long-life hydrophobic coating for an offshore photovoltaic support according to claim 1, characterized in that: The following steps are involved: 1) First, dissolve 0.3-1 parts of water-soluble polymer in water in advance and set aside; 2) Then, 100 parts of the silicon-aluminum ingredient, 1-2 parts of a water reducer, and 1-5 parts of an expansion agent were mixed and stirred at a low speed of 140 rpm using a JJ-5 mixer to uniformly mix the mixture; 3) Then, 10-30 parts of an alkali activator and 40-60 parts of water are added to the mixture and stirred at a low speed of 140 rpm to obtain a fresh slurry; 4) Finally, 0.5-2 parts of surface modifier was added to the fresh slurry and stirred at 285 rpm to obtain a hydrophobic coating.

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