Gradient construction method for anticorrosive coating of offshore photovoltaic support

Abstract

The invention provides a gradient construction method for an anti-corrosion coating of a marine photovoltaic support, and relates to the technical field of marine photovoltaic. The method comprises the following steps: carrying out surface treatment on the bracket, wherein the surface treatment comprises one of steel structure defect repair, pollutant removal, soluble salt grading treatment and composite abrasive blasting; sequential control coating is conducted on the support subjected to surface treatment, sequential control coating comprises the steps that pre-coating operation and spraying operation are completed within 4-6 hours after abrasive blasting is conducted on the composite abrasive, welding seam topology filling is conducted through bi-component epoxy resin in the pre-coating operation, gradient film thickness control is conducted in the spraying operation, and the spraying operation is completed within 4-6 hours after abrasive blasting is conducted on the composite abrasive. The film thickness of the edge area of the stent is increased by 20-30% compared with the film thickness of the plane area; repairing operation is conducted on the coated support, the repairing operation comprises selectively executing steel plate-level repairing or finish paint-level repairing based on the detection result of the damage depth of the coating, the steel plate-level repairing adopts a laser rust removal and three-coating step curing process, the anti-corrosion effect of the anti-corrosion coating can be improved, and the service life of the anti-corrosion coating can be prolonged.

Description

Technical Field

[0001] The present disclosure relates to the field of offshore photovoltaic technology, and in particular to a method for constructing a gradient anti-corrosion coating for an offshore photovoltaic support. Background Art

[0002] Photovoltaics is a power generation system that uses the photovoltaic effect of semiconductor materials to convert solar radiation into electrical energy. Photovoltaics, which derive their energy from solar energy, are a clean, safe, and renewable energy source. Therefore, photovoltaic power generation has promising application prospects.

[0003] Currently, most commonly used photovoltaic power generation systems are installed on land. However, due to limited land space and the obstruction of buildings or plants, the space for photovoltaic installation is relatively limited. Therefore, considering the efficiency of receiving solar energy and the space for photovoltaic installation, the sea surface becomes a better choice for photovoltaic installation. For offshore photovoltaic projects, the construction location is a typical marine atmospheric corrosion environment. The marine atmosphere is humid, and liquid film is easily formed on the surface of steel. The marine atmosphere contains a lot of salt, mainly NaCl. When salt particles settle on the metal surface, they absorb moisture and increase the conductivity of the surface liquid film. At the same time, chloride ions themselves are highly corrosive, which aggravates the corrosion of the metal surface, thereby reducing the strength and life of the bracket, and even causing damage to the bracket, resulting in the detachment of the photovoltaic.

[0004] It should be noted that the information disclosed in the above background technology section is only used to enhance the understanding of the background of the present disclosure, and therefore may include information that does not constitute prior art known to ordinary technicians in the field. Summary of the Invention

[0005] In view of this, a gradient construction method for the anti-corrosion coating of an offshore photovoltaic bracket is provided, which can improve the anti-corrosion performance and service life of the anti-corrosion coating on the bracket, thereby improving the reliability of offshore photovoltaics.

[0006] Other features and advantages of the present disclosure will become apparent from the following detailed description, or may be learned in part by practice of the present disclosure.

[0007] According to one aspect of the present disclosure, a method for constructing a gradient anti-corrosion coating on an offshore photovoltaic support is provided, wherein the support comprises a metal material, and the method comprises:

[0008] Step S1, performing surface treatment on the bracket, wherein the surface treatment includes at least one of steel structure defect repair, contaminant removal, soluble salt classification treatment, and composite abrasive sandblasting, wherein the soluble salt classification treatment includes three fresh water rinses and two salt tests alternately performed until the surface salt content of the bracket is ≤15 mg / m2;

[0009] Step S2, performing time-controlled coating on the surface-treated bracket, wherein the time-controlled coating includes completing a pre-coating operation and a spraying operation within 4 to 6 hours after the composite abrasive sandblasting, wherein the pre-coating operation uses a two-component epoxy resin for weld topological filling, and the spraying operation implements gradient film thickness control so that the film thickness of the edge area of ​​the bracket is 20% to 30% greater than the film thickness of the flat area;

[0010] Step S3: Repairing the painted bracket, wherein the repairing operation includes selectively performing steel plate-level repair or topcoat-level repair based on the coating damage depth detection result, wherein the steel plate-level repair adopts laser rust removal and three-coat step curing process.

[0011] In an exemplary embodiment of the present disclosure, in step S2, the gradient film thickness control includes:

[0012] An adjustable fan-shaped nozzle is used to implement vertical spraying in the edge area and oblique-angle spraying in the flat area. The number of spraying passes in the edge area is at least 1-2 more than that in the flat area. The angle of vertical spraying is 90±5°, and the angle of oblique spraying is 45±5°.

[0013] In an exemplary embodiment of the present disclosure, in step S2, the two-component epoxy resin includes component A and component B, wherein component A includes an epoxy resin modified with nano zinc oxide, and component B includes a cardanol derivative curing agent, and the mixing volume ratio of A:B is 3:1;

[0014] The pre-coating operation includes: using the two-component epoxy resin to form an anti-permeation barrier at the weld with a thickness of 1.5-2 times the thickness of the plane area.

[0015] In an exemplary embodiment of the present disclosure, in step S2, in the timing-controlled coating, the time interval between the pre-coating operation and the spraying operation follows the following functional relationship: t = K × (25-T) / ln (RH + 1); where t is the maximum allowable interval time, T is the ambient temperature, RH is the relative humidity, and K is a process correction coefficient of 0.8 to 1.2.

[0016] In an exemplary embodiment of the present disclosure, in step S3, the repair operation includes:

[0017] A drone equipped with an infrared spectrometer performs damage detection; when an iron element signal is detected, steel plate-level repair is activated; when only organic coating components are detected, topcoat-level repair is activated.

[0018] In an exemplary embodiment of the present disclosure, in step S3, the three-coat step curing process includes:

[0019] The first layer of epoxy zinc-rich primer is surface-dried under humidity ≤ 70%; the second layer of epoxy micaceous iron intermediate paint is cured by gradient temperature increase at 60°C to 80°C; the third layer of polysiloxane topcoat triggers the cross-linking reaction under UV light.

[0020] In an exemplary embodiment of the present disclosure, in step S3, the process parameters of the laser rust removal include:

[0021] The laser wavelength is 1064nm, the pulse frequency is 20kHz~50kHz, the scanning speed is 5mm / s~10mm / s, and a 5μm~10μm micro-melted oxide layer is generated on the surface after rust removal.

[0022] In an exemplary embodiment of the present disclosure, in step S1, the fresh water flushing uses brackish water at 40°C to 50°C, and the salinity of the brackish water is 0.5‰ to 1‰. After flushing, vortex air knife drying is performed with a wind speed of 15m / s to 20m / s, and the residual moisture on the surface after drying is ≤200mg / m2.

[0023] In an exemplary embodiment of the present disclosure, in step S1, the composite abrasive sandblasting includes:

[0024] Cast steel shot with a particle size of 0.6mm to 1.0mm and angular steel sand are mixed in a ratio of 1:2, the sandblasting pressure is 0.7Mpa to 0.9Mpa, the spraying distance is 150mm to 300mm, and the surface roughness forms a three-dimensional anchor chain structure of Rz=80±5μm.

[0025] In an exemplary embodiment of the present disclosure, the properties of the anti-corrosion coating include:

[0026] Cathodic peeling resistance ≤3mm, edge corrosion resistance coefficient ≥0.85.

[0027] The present disclosure provides a gradient construction method for an anti-corrosion coating of an offshore photovoltaic support. The method improves the surface quality of the support before the anti-corrosion coating is formally sprayed by performing one of the following steps: steel structure defect repair, pollutant removal, soluble salt classification treatment, and composite abrasive sandblasting on the support surface, thereby avoiding the anti-corrosion coating from falling off due to surface defects of the support, and improving the bonding between the support surface and the anti-corrosion coating; performing time-controlled spraying on the support after the surface treatment, wherein defects such as welds are filled by pre-spraying, thereby ensuring the uniformity of the anti-corrosion coating, avoiding the occurrence of stepped coatings that affect the strength of subsequent anti-corrosion coatings, and then forming a gradient coating by spraying. A smooth gradient film layer is formed so that the thickness of the edge area of ​​the bracket is greater than that of the flat area, so as to avoid rapid corrosion of the edge area due to seawater accumulation or long-term contact with seawater, improve the strength of the anti-corrosion coating in the edge area, and thus increase the service life of the entire anti-corrosion coating; after the bracket is painted, it is repaired, and the steel plate level repair or topcoat level repair is selectively performed based on the coating damage depth detection result. This repair operation method can repair the anti-corrosion coating in an all-round way, avoid the anti-corrosion coating being partially weak and affecting the service life of the entire coating, and form an anti-corrosion coating with high strength, good uniformity and long service life, which is especially suitable for high-corrosion environment at sea.

[0028] It is to be understood that the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings are incorporated into and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification, are used to explain the principles of the present disclosure. Obviously, the drawings described below are only some embodiments of the present disclosure, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0030] Figure 1 This is a flow chart of a method for constructing a gradient of an anti-corrosion coating for an offshore photovoltaic support in an exemplary embodiment of the present disclosure. DETAILED DESCRIPTION

[0031] Example embodiments will now be described more fully with reference to the accompanying drawings. However, the example embodiments can be implemented in many forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the concepts of the example embodiments to those skilled in the art. Like reference numerals in the figures represent identical or similar structures, and thus their detailed descriptions will be omitted. Furthermore, the figures are merely schematic illustrations of the present disclosure and are not necessarily drawn to scale.

[0032] Although relative terms such as "upper" and "lower" are used in this specification to describe the relationship of one illustrated component to another, these terms are used herein for convenience only, such as in accordance with the orientation of the illustrations in the accompanying drawings. It will be understood that if the illustrated device were flipped upside down, the component described as "upper" would become the component "lower." When a structure is referred to as "on" another structure, this may mean that the structure is integrally formed with the other structure, that the structure is "directly" disposed on the other structure, or that the structure is "indirectly" disposed on the other structure via the other structure.

[0033] The terms "a", "an", "the", "said" and "at least one" are used to indicate the presence of one or more elements / components / etc.; the terms "including" and "having" are used to express open-ended inclusion and mean that additional elements / components / etc. may be present in addition to the listed elements / components / etc.; the terms "first", "second" and "third" etc. are used only as labels and are not intended to limit the quantity of their objects.

[0034] In the related art, photovoltaic systems are devices that convert solar energy into electrical energy. Therefore, their installation must be tailored to the angle of the sun, placing high demands on their location. Since photovoltaic support structures are easier to install on land, photovoltaic applications are currently primarily on land. Corrosion factors affecting photovoltaic support structures on land are relatively rare, and corrosion protection for photovoltaic support structures only considers land-based factors. However, due to the limitations of land, consideration is being given to installing photovoltaic systems on the sea surface to improve their efficiency. However, the ocean is a very harsh corrosive environment, especially in the splash zone. Steel structures are periodically wetted by seawater, often experiencing alternating dry and wet states. With ample oxygen supply, salt concentration, and the synergistic effects of sunlight, wind, and the seawater environment, corrosion is particularly severe. Generally speaking, the corrosion rate of the same steel in the splash zone can be 3 to 10 times higher than in a fully immersed seawater area, with an average corrosion rate of approximately 0.3 to 1.0 mm / year.

[0035] Offshore supports are mostly constructed of galvanized steel or aluminum alloy. These materials can generally meet their designed service life in less harsh corrosive environments (such as on land). However, in highly corrosive environments, they often experience severe corrosion before reaching their service life. In particular, in marine corrosive environments, the material failure time is significantly shortened. Once a weak part of the support fails due to corrosion, it will have a serious impact on the performance of the entire support structure, further affecting the normal operation and safety of offshore photovoltaic systems. Therefore, it is very necessary to carry out effective anti-corrosion treatment on the steel structure of offshore photovoltaic supports.

[0036] Based on this, the embodiment of the present disclosure provides a method for constructing a gradient anti-corrosion coating of an offshore photovoltaic bracket, wherein the bracket includes a metal material, such as Figure 1 As shown, the method includes: steps S1 to S3.

[0037] Step S1: performing surface treatment on the bracket, wherein the surface treatment includes at least one of steel structure defect repair, contaminant removal, soluble salt classification treatment, and composite abrasive sandblasting, wherein the soluble salt classification treatment includes three fresh water rinses and two salt tests alternatingly until the surface salt content of the bracket is ≤15 mg / m2;

[0038] Step S2: performing sequential coating on the surface-treated stent, wherein the sequential coating includes completing a pre-coating operation and a spraying operation within 4 to 6 hours after composite abrasive sandblasting, wherein the pre-coating operation uses a two-component epoxy resin for weld topological filling, and the spraying operation implements gradient film thickness control so that the film thickness of the edge area of ​​the stent is 20% to 30% greater than the film thickness of the flat area;

[0039] Step S3: performing repair work on the painted bracket, wherein the repair work includes selectively performing steel plate level repair or topcoat level repair based on the coating damage depth detection result, wherein the steel plate level repair adopts laser rust removal and three-coat step curing process.

[0040] The present disclosure provides a gradient construction method for an anti-corrosion coating of an offshore photovoltaic support. The method improves the surface quality of the support before the anti-corrosion coating is formally sprayed by performing one of the following steps: steel structure defect repair, pollutant removal, soluble salt classification treatment, and composite abrasive sandblasting on the support surface, thereby avoiding the anti-corrosion coating from falling off due to surface defects of the support, and improving the bonding between the support surface and the anti-corrosion coating; performing time-controlled spraying on the support after the surface treatment, wherein defects such as welds are filled by pre-spraying, thereby ensuring the uniformity of the anti-corrosion coating, avoiding the occurrence of stepped coatings that affect the strength of subsequent anti-corrosion coatings, and then forming a gradient coating by spraying. A smooth gradient film layer is formed so that the thickness of the edge area of ​​the bracket is greater than that of the flat area, so as to avoid rapid corrosion of the edge area due to seawater accumulation or long-term contact with seawater, improve the strength of the anti-corrosion coating in the edge area, and thus increase the service life of the entire anti-corrosion coating; after the bracket is painted, it is repaired, and the steel plate level repair or topcoat level repair is selectively performed based on the coating damage depth detection result. This repair operation method can repair the anti-corrosion coating in an all-round way, avoid the anti-corrosion coating being partially weak and affecting the service life of the entire coating, and form an anti-corrosion coating with high strength, good uniformity and long service life, which is especially suitable for high-corrosion environment at sea.

[0041] It should be noted that the method provided by the present disclosure is applicable to offshore photovoltaic brackets, which may include metal materials. For example, the bracket may be made entirely of alloy steel or other materials; or it may be made of alloy mixed with non-metallic materials, for example, steel mixed with concrete; or the bracket body may be made of non-metallic materials, and metal materials may be used in certain parts of the bracket, such as metal welding at welds. It should be understood that the method provided by the present disclosure is applicable to the materials of the above brackets and brackets made after adaptive adjustment or change of the above materials. The bracket may include multiple components, and the multiple components form a grid structure. The bracket may also refer to a single component itself. The bracket may have different structures or different numbers of components, which can be selected according to the actual design requirements of the bracket.

[0042] In addition, the offshore photovoltaic support provided by the present disclosure can be set at sea level to provide support and fixation for photovoltaic modules set on the sea surface. Among them, the photovoltaic module may include multiple photovoltaic panels, and the specific structure of each photovoltaic panel can be understood as a photovoltaic panel structure available in the art. The specific number of photovoltaic panels in the photovoltaic module can be adaptively selected and adjusted according to actual design requirements, and the specific structure and constituent components of the support can be selected and adaptively adjusted according to the actual design requirements of the photovoltaic module, so that the support can provide sufficient support and support angle for the photovoltaic module to ensure the normal operation of the photovoltaic module.

[0043] In the present disclosure, the bracket may include a plane area and an edge area, wherein, within a single component of the bracket, for example, when the component is a steel pipe, the plane area may refer to the main body of the component and the surface with higher flatness, and the plane area may refer to the pipe body of the steel pipe; the edge area may refer to the edge of the component and the surface with lower flatness, and the edge area may refer to the end of the steel pipe. If the bracket is composed of multiple components, for the entire bracket, the plane area may refer to the main structure of the bracket, and the edge area may refer to the edge structure of the bracket. The edge structure may surround the main structure, and the area of ​​seawater contacted by the edge structure may be larger than that of the main structure. Of course, the plane area and edge area of ​​the bracket do not have strict boundaries and can be determined according to actual use needs. In the following embodiments of the present disclosure, the bracket is a single component. When the bracket is a grid structure composed of multiple components, the single component can be adaptively deformed or adjusted, all within the scope of protection of the present disclosure.

[0044] The following is a detailed description of the various steps of the method for constructing a gradient anti-corrosion coating for an offshore photovoltaic support provided by an embodiment of the present disclosure with reference to the accompanying drawings:

[0045] In an embodiment provided in the present disclosure, in step S1 , the bracket is surface treated.

[0046] The surface treatment includes performing one of steel structure defect repair, pollutant removal, soluble salt classification treatment, and composite abrasive sandblasting on the surface of the bracket.

[0047] In some embodiments, steel structure defect repair may refer to preliminary defect repair treatment on the bracket blank. The presence of steel structure defects will affect the adhesion of the paint, resulting in the paint not being able to exert its optimal anti-corrosion performance, and will cause premature rust in these areas. Therefore, before surface treatment, the bracket needs to be repaired for steel structure defects to reduce or eliminate the impact of structural defects on the coating quality.

[0048] In some specific embodiments, steel structure defect repair may include chamfering sharp free edges or gas-cut edges. For example, a grinding wheel may be used to round the free edges or gas-cut edges to a diameter greater than or equal to 2 mm, without any spatter or sharp angles remaining, to ensure a smooth transition of the sharp edges.

[0049] In some specific embodiments, steel structure defect repair may include processing welding defects such as weld beans, spatter, pores, and irregular welds. For example, weld beans can be removed with a grinder or a shovel hammer, and manual welds with irregular or sharp surfaces can be polished smooth. Bite marks with a depth exceeding 0.2 mm and a width slightly larger than the depth can be repaired by welding and polishing.

[0050] In some specific embodiments, steel structure defect repair may include processing of pores and intermittent welds, for example, filling and smoothing the pores.

[0051] In some embodiments, in order to improve the bonding between the subsequent anti-corrosion coating and the stent surface, the stent surface needs to be decontaminated to remove oil, water, grease, salt, cutting fluid, antifreeze and other chemical reagents or pollutants on the stent surface to ensure the cleanliness of the stent surface.

[0052] In some specific embodiments, pollutant removal includes grease removal. For example, for large areas of oil stains, industrial metal cleaner can be sprayed on the contaminated surface. After immersion for 5-10 minutes, the surface is scrubbed with a stiff brush or mop to allow the oil and grease to react fully, and then rinsed with fresh water. The immersion time can be 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, etc.; for small areas of oil stains, the contaminated surface can be wiped with a rag dipped in a solvent to fully dissolve the oil and grease, and then wiped dry with a clean rag. The wiping should be performed three to four times, and a clean rag should be used each time.

[0053] In some embodiments, in order to prevent the early osmotic pressure blistering of the anti-corrosion coating due to soluble salts, the soluble salts on the surface of the stent need to be graded. The soluble salt graded treatment includes three fresh water rinses and two salt tests alternately until the surface salt content of the stent is ≤15mg / m2 .

[0054] Specifically, fresh water flushing can be carried out with brackish water at 40°C to 50°C, and the salinity of the brackish water is 0.5‰ to 1‰, for example, the salinity can be 0.5‰, 0.6‰, 0.7‰, 0.8‰, 0.9‰, 1.0‰, etc. After flushing, a vortex air knife is used to dry the surface of the bracket, and the wind speed of the vortex air knife can be 15m / s to 20m / s, for example, the wind speed can be 15m / s, 16m / s, 17m / s, 18m / s, 19m / s, 20m / s, etc.; after drying, the surface of the bracket is The residual moisture is ≤200mg / m2 to improve the cleanliness of the bracket surface, wherein three fresh water rinses and two salt tests are performed alternately, that is, a salt test is performed after each fresh water rinse until the surface salt content of the bracket is ≤15mg / m2. The water pressure of the three fresh water rinses can be the same, that is, a higher water pressure is used for each rinse of the bracket surface; or the water pressure of the three rinses is distributed in a decreasing manner, and the water pressure of each rinse is adaptively adjusted according to the salt content to avoid damage to the bracket surface caused by excessive water pressure. The present disclosure adopts three fresh water rinses for graded treatment of soluble salts, but it should be understood that three fresh water rinses can basically make the surface salt content of the bracket ≤15mg / m2. However, if the surface salt content of the bracket is still high after three fresh water rinses, fresh water rinses or other cleaning methods can be continued to reduce the salt content on the bracket surface.

[0055] In some embodiments, in order to ensure that the surface of the stent has a certain degree of roughness so as to improve the bonding between the anti-corrosion coating and the stent surface, the stent surface needs to be sandblasted with composite abrasives.

[0056] In some specific embodiments, the composite abrasive sandblasting includes: cast steel shot with a particle size of 0.6 mm to 1.0 mm and angular steel sand mixed in a ratio of 1:2, the sandblasting pressure is 0.7 MPa to 0.9 MPa, the spray distance is 150 mm to 300 mm, and the surface roughness forms a three-dimensional anchor chain structure of Rz = 80 ± 5 μm; wherein, the particle size of the cast steel shot can be 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, etc.; the sandblasting pressure can be 0.7 MPa, 0.75 MPa, 0.8 MPa, 0.85 MPa, 0.9 MPa, etc., and the surface roughness can be 75 μm, 77 μm, 80 μm, 83 μm, 85 μm, etc.

[0057] In the embodiment provided in the present disclosure, in step S2, the bracket after surface treatment is subjected to time-controlled painting.

[0058] Among them, the timing-controlled coating includes completing the pre-coating operation and the spraying operation within 4 to 6 hours after the composite abrasive sandblasting to ensure that the spraying operation is performed on the surface of the bracket with a preset cleanliness. After 6 hours of sandblasting, the surface of the bracket is prone to rust or contamination. If the spraying operation is not performed after 6 hours of sandblasting, the surface of the bracket needs to be re-treated to ensure the spraying quality of the bracket surface.

[0059] In some embodiments, the sequentially controlled coating includes a pre-coating operation, which uses a two-component epoxy resin to perform weld topological filling.

[0060] In some specific embodiments, the two-component epoxy resin includes component A and component B, wherein component A may include an epoxy resin modified with nano-zinc oxide, and component B may include a cardanol derivative curing agent. The mixing volume ratio of A:B can be 3:1, and the viscosity of component A is adjusted by component B to ensure that the viscosity of the two-component epoxy resin is suitable for spraying on the surface of the bracket.

[0061] In some specific embodiments, the pre-coating operation includes using a two-component epoxy resin to form an anti-permeation barrier at the weld with a thickness of 1.5 to 2 times the thickness of the planar area, so as to improve the corrosion resistance of the weld.

[0062] In some specific embodiments, the pre-coating operation may also include using a two-component epoxy resin to pre-spray edges, various holes, rough welds, surface unevenness, weld cracks, bites, free edges, escalators and handrails, screws and bolts, and areas with complex structures that are difficult to spray, so as to improve the corrosion resistance of weak parts of the bracket.

[0063] In some embodiments, the timing-controlled coating includes a spraying operation, and the spraying operation implements gradient film thickness control to implement targeted spraying on the surface of the bracket, ensuring that anti-corrosion coatings of different thicknesses are formed on different parts of the bracket surface, and ensuring the uniformity of anti-corrosion performance of various parts of the bracket surface.

[0064] In some specific embodiments, the gradient film thickness control includes: using an adjustable fan-shaped nozzle to implement vertical spraying in the edge area and oblique-angle spraying in the flat area, and the number of spraying passes in the edge area is at least 1-2 more than that in the flat area; wherein the angle of vertical spraying is 90±5°, for example, the angle of vertical spraying can be 85°, 86°, 87°, 88°, 89°, 90°, 91°, 92°, 93°, 94°, 95°, etc.; the angle of oblique-angle spraying is 45±5°, for example, the angle of oblique-angle spraying can be 40°, 41°, 42°, 43°, 44°, 45°, 46°, 47°, 48°, 49°, 50°, etc.

[0065] Specifically, vertical spraying in the edge area can allow more paint to accumulate in the edge area, making the anti-corrosion coating in the edge area thicker; using oblique angle spraying in the plane area can form a uniform anti-corrosion coating in the plane area, and the anti-corrosion coating in the plane area can be thinner than the anti-corrosion coating in the edge area, so that the edge area and the plane area form a gradient film thickness. On the one hand, it can save paint, and on the other hand, the gradient film layer can improve the uniformity of the anti-corrosion performance of the anti-corrosion coating, and avoid the anti-corrosion performance of some parts of the anti-corrosion coating being too low, which causes the anti-corrosion coating in some parts to fall off prematurely.

[0066] It should be noted that at the junction of the edge area and the plane area, the anti-corrosion coating has a smooth transition, and no stepped anti-corrosion coating structure is formed on the surface of the bracket, so as to avoid premature falling off of the anti-corrosion coating at the stepped structure, thereby improving the performance and anti-corrosion performance of the anti-corrosion coating.

[0067] In some embodiments, in sequential coating, the time interval between pre-coating and spraying follows the following functional relationship: t = K × (25-T) / ln (RH + 1). Here, t is the maximum allowable interval time, T is the ambient temperature, RH is the relative humidity, and K = a process correction factor of 0.8 to 1.2. By controlling the time interval between pre-coating and spraying using this functional relationship, it is possible to ensure that the coating layer during the pre-coating operation is not damaged by the spraying operation, and to ensure that the film layer formed by the spraying operation has good adhesion with the film layer formed by the pre-coating operation, thereby ensuring the quality of the anti-corrosion coating.

[0068] In the embodiment provided by the present disclosure, in step S3, a repair operation is performed on the painted bracket.

[0069] In some embodiments, the repairing operation includes selectively performing steel plate-level repairing or topcoat-level repairing based on the coating damage depth detection result.

[0070] Among them, since coating damage is difficult to detect as the coating depth increases, in order to improve the repairability of coating damage, the repair operation can include: using a drone equipped with an infrared spectrometer to perform damage detection; when an iron element signal is detected, activating steel plate-level repair; when only organic coating components are detected, activating topcoat-level repair.

[0071] Steel plate-level repair refers to repairing defects on the stent surface or within the anti-corrosion coating that contain metallic elements (such as iron); topcoat-level repair refers to repairing defects within the anti-corrosion coating that do not contain metallic elements. Furthermore, because stents are made of metal, steel plate-level repair can also refer to repairing defects on the stent surface and in the anti-corrosion coating near the stent surface; topcoat-level repair can refer to repairing defects in the anti-corrosion coating away from the stent surface.

[0072] In some specific embodiments, since the defects of the anti-corrosion coating close to the surface of the bracket are not convenient for observation with the naked eye, such defects are hidden deep and difficult to detect, and the defects will seriously affect the bonding between the anti-corrosion coating and the bracket surface. Therefore, in order to improve the bonding performance between the bracket surface and the anti-corrosion coating and eliminate defects, the repair work can adopt steel plate-level repair, wherein the steel plate-level repair adopts laser rust removal and three-coat step curing process.

[0073] The laser rust removal process parameters include: a laser wavelength of 1064 nm; a pulse frequency of 20 kHz to 50 kHz, for example, 20 kHz, 30 kHz, 40 kHz, or 50 kHz; a scanning speed of 5 mm / s to 10 mm / s, for example, 5 mm / s, 6 mm / s, 7 mm / s, 8 mm / s, 9 mm / s, or 10 mm / s; and a micro-melted oxide layer of 5 μm to 10 μm in thickness formed on the surface after rust removal. For example, the thickness of the micro-melted oxide layer can be 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, or 10 μm. Laser rust removal can effectively remove rust from the damaged stent surface until the stent surface is exposed. Furthermore, after the damaged stent surface is exposed, the intact anti-corrosion coating within 15 cm to 20 cm around the damaged area can be pulled out of the groove to ensure a smooth transition between the repair coating and the original anti-corrosion coating.

[0074] Among them, the three-coat step curing process includes: the first layer of epoxy zinc-rich primer is surface dried under humidity ≤ 70%; the second layer of epoxy micaceous iron intermediate paint is gradiently cured at a temperature of 60℃ to 80℃, for example, the curing temperature can be 60℃, 65℃, 70℃, 75℃, 80℃, etc.; the third layer of polysiloxane topcoat triggers a cross-linking reaction under UV light. The three-coat step curing process is used at the damaged part of the anti-corrosion coating to improve the repair quality of the damaged part and ensure the organic combination of the repaired anti-corrosion coating with the original anti-corrosion coating, thereby improving the overall anti-corrosion performance of the anti-corrosion coating.

[0075] Epoxy zinc-rich primer can improve the adhesion of the anti-corrosion coating on the surface of the bracket, thereby preventing the anti-corrosion coating from falling off after repair; epoxy micaceous iron intermediate paint has good bonding with epoxy zinc-rich primer and has sealing properties, forming an excellent anti-corrosion effect on the bracket; polysiloxane topcoat has outdoor weather resistance, can resist ultraviolet rays and long-term light, maintain the integrity of the anti-corrosion coating, and can resist salt spray erosion, reducing the maintenance frequency of the anti-corrosion coating.

[0076] In some specific embodiments, topcoat-level repair may include: removing contaminants from the anti-corrosion coating surface; removing damaged anti-corrosion coating with sandpaper; beveling the intact paint layer within 15-20 cm around the damaged area to ensure a smooth transition between the repair coating and the original coating; and spraying the damaged area to ensure that the repair coating is flush or approximately flush with the original coating. Specifically, topcoat-level repair may use a two-component epoxy resin to repair the damaged area, filling the damaged area and ensuring the integrity of the anti-corrosion coating.

[0077] The performance of the anti-corrosion coating formed by the method provided in the present disclosure may include: resistance to cathodic peeling ≤ 3mm, edge corrosion resistance coefficient ≥ 0.85, which can meet the laying requirements of offshore photovoltaics, increase the service life of the anti-corrosion coating, thereby improving the full life cycle of offshore photovoltaic equipment and ensuring the safe and stable operation of offshore photovoltaics.

[0078] The method provided by the present disclosure is described below with reference to specific embodiments:

[0079] Example 1 (standard working conditions):

[0080] Step S1: Surface treatment of the bracket:

[0081] Treat welding defects such as weld beans, spatter, pores, irregular welds, etc.

[0082] The surface of the bracket was rinsed three times with brackish water at 40°C and a salinity of 0.8‰, with an air knife drying speed of 15m / s each time until the salt content dropped to 12mg / m2;

[0083] Cast steel shot It was mixed with angular steel sand in a ratio of 1:2, and the blasting pressure was 0.8 MPa and the blasting distance was 200 mm to obtain a stent surface with Rz = 82 μm.

[0084] Step S2: performing gradient coating on the surface of the bracket after surface treatment:

[0085] The pre-coating process uses nano-zinc oxide modified epoxy resin and cardanol derivative curing agent to form a 160μm thick film layer on the weld. The volume ratio of nano-zinc oxide modified epoxy resin and cardanol derivative curing agent is 3:1.

[0086] The spraying operation uses a mixture of nano-zinc oxide-modified epoxy resin and cardanol derivative curing agent in a volume ratio of 3:1. Three vertical sprays are applied to the edge area at a vertical spraying angle of 90° to form an anti-corrosion coating with a film thickness of 320μm. Two oblique sprays are applied to the flat area at an oblique spraying angle of 45° to form an anti-corrosion coating with a film thickness of 250μm.

[0087] When the ambient temperature is 20° C. and the RH is 65%, the interval between the pre-coating operation and the spraying operation is t=1.0×(25−20) / ln(65+1)=4.2 h.

[0088] Step S3: Repairing operation:

[0089] The drone detected the Fe element signal and the damage area was 3cm2, activating the steel plate-level repair;

[0090] A laser with a wavelength of 1064nm and a frequency of 30kHz is used to remove rust from the damaged area, generating an 8μm micro-melted layer.

[0091] The damaged parts were repaired using a three-coat step-curing process, in which the epoxy zinc-rich primer was dried at a humidity of 70%; the epoxy micaceous iron intermediate paint was cured at 60°C for 2 hours; and the polysiloxane topcoat was formed by UV irradiation for 1 hour.

[0092] Table 1

[0093] Test items Example 1 Conventional process Improvement Salt spray resistance time (h) 6215 2850 +118％ Edge corrosion resistance coefficient 0.89 0.62 +43％ Cathodic stripping (mm) 2.8 7.1 -61％ Adhesion (MPa) 15.4 8.3 +85％

[0094] As can be seen from Table 1, the stent anti-corrosion coating formed by this method in Example 1 has significantly improved performance in salt spray resistance time, edge corrosion resistance coefficient, cathodic peeling, adhesion, etc. compared with the stent anti-corrosion coating formed by the conventional process, thereby proving that the stent anti-corrosion coating disclosed in the present invention has good anti-corrosion performance.

[0095] Example 2 (high temperature and high humidity conditions):

[0096] Step S1: Surface treatment of the bracket:

[0097] Treat welding defects such as weld beans, spatter, pores, irregular welds, etc.

[0098] The surface of the bracket was rinsed three times with brackish water at 40°C and a salinity of 0.8‰, with an air knife drying speed of 18m / s each time until the salt content dropped to 12mg / m2;

[0099] Cast steel shot Mixed with angular steel sand in a ratio of 1:2, the blasting pressure was 0.8 MPa and the blasting distance was 200 mm to obtain a stent surface with Rz = 82 μm;

[0100] Step S2: performing gradient coating on the surface of the bracket after surface treatment:

[0101] The pre-coating process uses nano-zinc oxide modified epoxy resin and cardanol derivative curing agent to form a 160μm thick film layer on the weld. The volume ratio of nano-zinc oxide modified epoxy resin and cardanol derivative curing agent is 3:1.

[0102] The spraying operation uses a mixture of nano-zinc oxide-modified epoxy resin and cardanol derivative curing agent in a volume ratio of 3:1. Three vertical sprays are applied to the edge area at a vertical spraying angle of 90° to form an anti-corrosion coating with a film thickness of 320μm. Two oblique sprays are applied to the flat area at an oblique spraying angle of 40° to form an anti-corrosion coating with a film thickness of 250μm.

[0103] Among them, when the ambient temperature is 32°C and the RH is 85%, the interval between the pre-coating operation and the spraying operation is t = 1.2 × (25-32) / ln (85+1) = 3.1h;

[0104] Step S3: Repairing operation:

[0105] The drone detected the Fe element signal and the damage area was 3cm2, activating the steel plate-level repair;

[0106] A laser with a wavelength of 1064nm and a frequency of 30kHz is used to remove rust from the damaged area, generating an 8μm micro-melted layer.

[0107] The damaged parts were repaired using a three-coat step-curing process, in which the epoxy zinc-rich primer was surface-dried at a humidity of 70%; the epoxy micaceous iron intermediate paint was cured at 80°C for 3 hours; and the polysiloxane topcoat was formed by UV irradiation for 1 hour.

[0108] Table 2

[0109] Test items Example 2 Conventional process Improvement Salt spray resistance time (h) 6325 2850 +122％ Edge corrosion resistance coefficient 0.92 0.62 +48％ Cathodic stripping (mm) 3.0 7.1 -57％ Adhesion (MPa) 16.5 8.3 +99％

[0110] As can be seen from Table 2, the stent anti-corrosion coating formed by this method in Example 2 has significantly improved performance in terms of salt spray resistance time, edge corrosion resistance coefficient, cathodic peeling, adhesion, etc. compared with the stent anti-corrosion coating formed by the conventional process, thereby proving that the stent anti-corrosion coating disclosed in the present invention has better anti-corrosion performance.

[0111] In addition, tests and statistics have shown that using this method to form a stent anti-corrosion coating can shorten the project cycle by approximately 22 days, reduce the annual maintenance cost by 350,000 yuan / km2, and the life of the anti-corrosion coating is expected to reach 25 years.

[0112] It should be noted that although the steps of the method for constructing a gradient anti-corrosion coating for an offshore photovoltaic support disclosed herein are described in a specific order in the accompanying drawings, this does not require or imply that the steps must be performed in this specific order, or that all steps shown must be performed to achieve the desired result. Additionally or alternatively, certain steps may be omitted, multiple steps may be combined into a single step, and / or a single step may be broken down into multiple steps.

[0113] Those skilled in the art will readily appreciate other embodiments of the present disclosure after considering the specification and practicing the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of the present disclosure that follow the general principles of the present disclosure and include common knowledge or customary techniques in the art not disclosed herein. The description and examples are to be considered as exemplary only, with the true scope and spirit of the present disclosure being indicated by the appended claims.

Claims

1. A method for constructing a gradient anti-corrosion coating on an offshore photovoltaic support, wherein the support comprises a metal material, characterized in that: include: Step S1, performing surface treatment on the bracket, wherein the surface treatment includes at least one of steel structure defect repair, contaminant removal, soluble salt classification treatment, and composite abrasive sandblasting, wherein the soluble salt classification treatment includes three fresh water rinses and two salt tests alternately performed until the surface salt content of the bracket is ≤15 mg / m2; Step S2, performing time-controlled coating on the surface-treated bracket, wherein the time-controlled coating includes completing a pre-coating operation and a spraying operation within 4 to 6 hours after the composite abrasive sandblasting, wherein the pre-coating operation uses a two-component epoxy resin for weld topological filling, and the spraying operation implements gradient film thickness control so that the film thickness of the edge area of ​​the bracket is 20% to 30% greater than the film thickness of the flat area; Step S3: Repairing the painted bracket, wherein the repairing operation includes selectively performing steel plate-level repair or topcoat-level repair based on the coating damage depth detection result, wherein the steel plate-level repair adopts laser rust removal and three-coat step curing process.

2. The method according to claim 1, characterized in that In step S2, the gradient film thickness control includes: An adjustable fan-shaped nozzle is used to implement vertical spraying in the edge area and oblique-angle spraying in the flat area. The number of spraying passes in the edge area is at least 1-2 more than that in the flat area. The angle of vertical spraying is 90±5°, and the angle of oblique spraying is 45±5°.

3. The method according to claim 1, characterized in that In step S2, the two-component epoxy resin includes component A and component B, wherein component A contains nano-zinc oxide-modified epoxy resin, and component B contains a cardanol derivative curing agent, and the mixing volume ratio of A:B is 3:1; The pre-coating operation includes: using the two-component epoxy resin to form an anti-permeation barrier at the weld with a thickness of 1.5-2 times the thickness of the plane area.

4. The method according to any one of claims 1 to 3, characterized in that In step S2, in the timing-controlled coating, the time interval between the pre-coating operation and the spraying operation follows the following functional relationship: t = K × (25-T) / ln (RH + 1); where t is the maximum allowable interval time, T is the ambient temperature, RH is the relative humidity, and K is a process correction coefficient of 0.8 to 1.

2.

5. The method according to claim 1, wherein In step S3, the repair operation includes: A drone equipped with an infrared spectrometer performs damage detection; when an iron element signal is detected, steel plate-level repair is activated; when only organic coating components are detected, topcoat-level repair is activated.

6. The method according to claim 1, characterized in that In step S3, the three-coat step curing process includes: The first layer of epoxy zinc-rich primer is surface-dried under humidity ≤ 70%; the second layer of epoxy micaceous iron intermediate paint is cured by gradient temperature increase at 60°C to 80°C; the third layer of polysiloxane topcoat triggers the cross-linking reaction under UV light.

7. The method according to any one of claims 1, 5 or 6, characterized in that: In step S3, the process parameters of the laser rust removal include: The laser wavelength is 1064nm, the pulse frequency is 20kHz~50kHz, the scanning speed is 5mm / s~10mm / s, and a 5μm~10μm micro-melted oxide layer is generated on the surface after rust removal.

8. The method according to claim 1, characterized in that In step S1, the fresh water flushing is carried out with brackish water at 40℃~50℃, the salinity of the brackish water is 0.5‰~1‰, and after flushing, vortex air knife drying is carried out with a wind speed of 15m / s~20m / s. After drying, the residual moisture on the surface is ≤200mg / m 2 .

9. The method according to claim 1 or 8, characterized in that In step S1, the composite abrasive sandblasting includes: Cast steel shot with a particle size of 0.6mm to 1.0mm and angular steel sand are mixed in a ratio of 1:2, the sandblasting pressure is 0.7Mpa to 0.9Mpa, the spraying distance is 150mm to 300mm, and the surface roughness forms a three-dimensional anchor chain structure of Rz=80±5μm.

10. The method according to claim 1, characterized in that The properties of the anti-corrosion coating include: Cathodic peeling resistance ≤3mm, edge corrosion resistance coefficient ≥0.85.

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