Construction method of anti-corrosion protective layer for enhancing sealing performance of offshore wind power flange

Abstract

The invention provides a construction method of an anti-corrosion protective layer for enhancing the sealing performance of an offshore wind power flange, which comprises the following steps of: coating specific chemical composition slurry containing piezoelectric sensing filler and an electrochemical initiator, and sequentially executing a self-adaptive initial setting step and an electrochemical collaborative deep curing step based on piezoelectric signal feedback. A protective layer with high adhesive force and high compactness is successfully constructed; the method comprises the following steps: firstly, monitoring and triggering in-situ gelation of slurry in real time by using a signal generated by a piezoelectric filler when a pre-tightening force is applied, effectively fixing the form of the material, preventing the material from being extruded under high pressure, and then, applying a direct-current voltage between two flange surfaces to initiate uniform and thorough click chemical polymerization reaction from an interface, so as to realize the in-situ gelation of the slurry. The deep curing of the material in the narrow closed gap is realized, so that the technical problems that the traditional sealant is easy to extrude and the curing in the gap is difficult are solved, and finally, a flange connection interface with excellent long-term sealing performance and excellent corrosion resistance is obtained.

Description

Technical Field

[0001] This invention relates to the field of anti-corrosion coating technology, and in particular to a method for constructing an anti-corrosion protective layer to enhance the sealing performance of offshore wind turbine flanges. Background Technology

[0002] Offshore wind power equipment operates for extended periods in marine environments characterized by high salt spray and high humidity. Its tower structure is typically composed of multiple sections connected by large flanges. The narrow gaps formed between the flange joints are areas where corrosive media can easily penetrate and accumulate, leading to crevice corrosion and compromising the structural safety during operation.

[0003] In the prior art, liquid or paste-like sealing and anti-corrosion materials, such as two-component epoxy resin or polyurethane sealant, are usually applied to the surface of the flange connection before they are mated, in order to fill the gaps and block corrosive media.

[0004] However, the aforementioned existing technical solutions present significant technical challenges in practical applications. Tightening the flange requires extremely high bolt preload. During this preload application, the sealing material applied to the flange connection surface is still in a low-viscosity liquid or fluid state, and this material is squeezed out in large quantities from the narrow gap under immense pressure. This extrusion phenomenon results in an uncontrollable and uneven thickness of the protective layer between the flange surfaces after final curing, or even complete absence in localized areas, failing to form a continuous and complete physical barrier. Therefore, it is difficult to achieve reliable sealing and corrosion protection.

[0005] Furthermore, the gap formed after flange mating is a highly sealed space lacking air or moisture. This makes it impossible for sealing materials that rely on external moisture curing or solvent evaporation curing to achieve complete curing deep within the gap. If a two-component chemical curing material is used, its curing reaction begins with the mixture, making it difficult to coordinate its pot life. If the pot life is set too long, the material remains in a fluid state for an extended period, exacerbating the extrusion problem under the aforementioned pre-tightening force; if the pot life is set too short, the material may lose its fluidity or gel before the flange is properly aligned and pre-tightened, resulting in ineffective filling of the interfacial microstructure and also affecting the final sealing performance. Therefore, how to ensure that the protective material can fully fill the interface and achieve uniform and controllable deep curing within the sealed gap under the pressure conditions of in-situ flange tightening is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The first aspect of this disclosure provides a method for constructing an anti-corrosion protective layer to enhance the sealing performance of offshore wind turbine flanges, comprising the following steps: S1. Apply a chemical composition slurry to the flange connection surface, wherein the chemical composition slurry comprises an alkenyl resin, a thiol-based crosslinking agent, a piezoelectric sensing filler, and an electrochemical initiator; S2. Place the two flange connecting faces together and apply preload; S3. Monitor the piezoelectric signal generated by the piezoelectric sensing filler in the chemical composition slurry under the pre-tightening force, and determine the uniformity of the pre-tightening force and the initial setting state of the slurry based on the piezoelectric signal; S4. Apply a DC voltage between the two flange connection surfaces to initiate the curing of the chemical composition slurry; S5. After electrochemical synergistic deep curing is completed, apply the final designed torque.

[0007] In conjunction with the first aspect, the alkenyl resin is trimethylolpropane triallyl ether, the thiol-based crosslinking agent is pentaerythritol tetra(3-mercaptopropionate), the piezoelectric sensing filler is barium titanate, and the electrochemical initiator is tetrabutylammonium hexafluorophosphate.

[0008] In conjunction with the first aspect, the chemical composition slurry further comprises an interfacial coupling agent and a conductive additive, wherein the interfacial coupling agent is (3-mercaptopropyl)trimethoxysilane and the conductive additive is graphene nanosheets.

[0009] In conjunction with the first aspect, in S1, the wet film thickness of the chemical composition slurry coating is 300-600 μm.

[0010] In conjunction with the first aspect, before applying the preload in S2, a temporary insulating sleeve is used between the bolt and the flange hole to ensure electrical isolation between the two flange segments, and the preload is 30%-50% of the final design torque.

[0011] In conjunction with the first aspect, in S3, the piezoelectric signal is monitored using an adaptive curing control system with an integrated high-impedance voltage monitoring unit.

[0012] In conjunction with the first aspect, in S3, the criterion for determining that the piezoelectric signal has reached a stable threshold is that the fluctuation rate of the piezoelectric signal is less than 5% within a 30s period.

[0013] In conjunction with the first aspect, in S4, the range of the DC voltage is 8.0-15.0V, and the duration of applying the DC voltage is 90-180s.

[0014] A second aspect of this disclosure provides a chemical composition slurry for enhancing the sealing performance of offshore wind turbine flanges, comprising the following components by mass fraction: Alkenyl resin: 40.0%-68.45%; Thiol-based crosslinking agent: 15.0%-28.8%; Piezoelectric sensing filler: 15.0%-25.0%; Electrochemical initiator: 0.5%-2.0%; Interface coupling agent: 1.0%-4.0%; Conductive additives: 0.05%-0.2%.

[0015] In conjunction with the second aspect, the alkenyl resin is trimethylolpropane triallyl ether, the thiol-based crosslinking agent is pentaerythritol tetra(3-mercaptopropionate), the piezoelectric sensing filler is barium titanate, the electrochemical initiator is tetrabutylammonium hexafluorophosphate, the interfacial coupling agent is (3-mercaptopropyl)trimethoxysilane, and the conductive additive is graphene nanosheets.

[0016] Beneficial Effects: This disclosure provides a method for constructing an anti-corrosion protective layer to enhance the sealing performance of offshore wind turbine flanges. By applying a slurry containing a specific chemical composition of piezoelectric sensing filler and an electrochemical initiator, and sequentially performing an adaptive initial setting step based on piezoelectric signal feedback and an electrochemical synergistic deep curing step, a highly adhesive and dense protective layer is successfully constructed. This method first utilizes the signal generated by the piezoelectric filler when pre-tightening force is applied to monitor and trigger in-situ gelation of the slurry in real time, effectively fixing the material morphology and preventing it from being squeezed out under high pressure. Then, by applying a DC voltage between the two flange faces, a uniform and thorough click chemical polymerization reaction is initiated from the interface, achieving deep curing of the material within the narrow and sealed gap. This solves the technical problems of traditional sealants being easily squeezed out and difficult to cure within gaps, ultimately obtaining a flange connection interface with both excellent long-term sealing performance and superior anti-corrosion performance. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart illustrating a method for constructing an anti-corrosion protective layer to enhance the sealing performance of offshore wind turbine flanges, according to an embodiment of this disclosure. Detailed Implementation

[0018] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with those disclosed herein.

[0019] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. The singular forms “a,” “the,” and “the” as used in this disclosure and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any and all possible combinations of one or more of the associated listed items.

[0020] Figure 1This is a schematic flowchart illustrating a method for constructing an anti-corrosion protective layer to enhance the sealing performance of offshore wind turbine flanges according to an embodiment of the present disclosure, including the following steps: S1. Apply a chemical composition slurry to the flange connection surface, wherein the chemical composition slurry comprises an alkenyl resin, a thiol-based crosslinking agent, a piezoelectric sensing filler, and an electrochemical initiator; The alkenyl resin is trimethylolpropane triallyl ether, the thiol-based crosslinking agent is pentaerythritol tetra(3-mercaptopropionate), the piezoelectric sensing filler is barium titanate, and the electrochemical initiator is tetrabutylammonium hexafluorophosphate.

[0021] The chemical composition slurry further comprises an interface coupling agent and a conductive additive, wherein the interface coupling agent is (3-mercaptopropyl)trimethoxysilane and the conductive additive is graphene nanosheets.

[0022] In step S1, the wet film thickness of the chemical composition slurry coating is 300-600 μm.

[0023] This step involves uniformly coating a specially formulated chemical composition slurry onto the cleaned flange connection surface. This slurry is a multifunctional system with carefully designed components: trimethylolpropane triallyl ether serves as the alkenyl resin backbone, and pentaerythritol tetra(3-mercaptopropionate) acts as a thiol-based crosslinking agent; together, they form the main body of the subsequent curing reaction. Barium titanate, as a piezoelectric sensing filler, endows the slurry with the ability to sense mechanical pressure and generate electrical signals. Tetrabutylammonium hexafluorophosphate, as an electrochemical initiator, is the key trigger point for the subsequent electrochemical curing step. Furthermore, (3-mercaptopropyl)trimethoxysilane acts as an interfacial coupling agent to enhance the adhesion to the metal matrix, and graphene nanosheets, as a conductive additive, are used to optimize the electrical properties of the slurry. Strictly controlling the wet film thickness to 300-600 μm ensures sufficient material to fully fill the microscopic unevenness of the flange surface, forming an effective seal, while avoiding excessive thickness that could lead to over-extrusion or waste under pressure.

[0024] S2. Place the two flange connecting faces together and apply preload; Before applying the preload, a temporary insulating sleeve is used between the bolt and the flange hole to ensure electrical isolation between the two flange segments. The preload is 30%-50% of the final design torque.

[0025] This step completes the initial alignment and fixation of the flanges. Before closing, a temporary insulating sleeve is inserted between the bolts and the flange holes. This measure aims to electrically isolate the upper and lower flange segments from each other, creating the necessary conditions for applying a DC voltage between the two flange faces and forming an effective electric field loop in the subsequent step four. Then, a preload force between 30% and 50% of the final design torque is applied. This force value is carefully selected: it must be large enough to initially tighten the two flange segments and compress the grout in the middle, allowing it to begin flowing and filling the gap; but not too large, lest most of the material be squeezed out instantaneously before the grout has cured. This preload force also acts on the piezoelectric filler in the grout, preparing for the next step of monitoring and triggering.

[0026] S3. Monitor the piezoelectric signal generated by the piezoelectric sensing filler in the chemical composition slurry under the pre-tightening force, and determine the uniformity of the pre-tightening force and the initial setting state of the slurry based on the piezoelectric signal; In step S3, an adaptive curing control system with an integrated high-impedance voltage monitoring unit is used to monitor the piezoelectric signal.

[0027] In step S3, the criterion for determining whether the piezoelectric signal has reached a stable threshold is that the fluctuation rate of the piezoelectric signal is less than 5% within a 30s period.

[0028] When preload is applied to the flange, the pressure is transmitted to the barium titanate piezoelectric sensing filler in the slurry, causing it to generate a weak electrical signal due to the piezoelectric effect. These signals can be captured and analyzed in real time by an adaptive curing control system integrating a high-impedance voltage monitoring unit. The uniformity of the piezoelectric signal can indirectly reflect whether the preload is evenly distributed on the flange contact surface.

[0029] More importantly, the localized charge generated by the piezoelectric filler under pressure can trigger the thiol-olefin polymerization reaction in the slurry system, causing the slurry to transform from a liquid state to a gel state, achieving "initial setting". The system determines whether this initial setting process is complete by monitoring the fluctuation rate of the piezoelectric signal. When the fluctuation rate of the signal is less than 5% within a 30-second period, it indicates that the slurry has formed a stable gel network with a basically fixed morphology. At this point, it is determined that the stability threshold has been reached, and the next step can be safely carried out without worrying about a large amount of slurry being squeezed out.

[0030] S4. Apply a DC voltage between the two flange connection surfaces to initiate the curing of the chemical composition slurry; In step S4, the range of the DC voltage is 8.0-15.0V, and the duration of applying the DC voltage is 90-180s.

[0031] After confirming that the slurry has completed its initial setting, the adaptive curing control system switches modes, applying a DC voltage of 8.0 to 15.0V between the two electrically isolated flange segments. This electric field activates the electrochemical initiator tetrabutylammonium hexafluorophosphate in the slurry, causing it to oxidize at the anode (one of the flange faces), generating highly reactive free radicals. These free radicals then initiate a thiol-olefin click chemical polymerization reaction that begins at the flange metal interface and penetrates deep into the slurry. This electric field-driven curing method has the advantage of achieving coordinated, uniform, and thorough curing of the slurry from the interface to the interior, regardless of the tightness and depth of the gaps, forming a solid protective layer with high cross-linking density and stable performance. The voltage application time of 90 to 180 seconds ensures that the curing reaction is fully completed.

[0032] S5. After electrochemical synergistic deep curing is completed, apply the final designed torque.

[0033] This step aims to bring the flange connection to its final design mechanical state. After the electrochemical synergistic deep curing in step four, the intermediate slurry has completely transformed into a high-strength solid protective layer, possessing stable sealing and corrosion protection functions. At this point, the construction personnel remove the temporary insulating sleeve and external electrical connection devices, and then, according to the engineering design requirements, apply 100% of the final design torque to thoroughly tighten the flange bolts. Because the protective layer has been fully cured and possesses high mechanical strength, this final tightening operation will not cause material flow or extrusion, thus ensuring that, in its final service state, the protective layer thickness between the flange connection surfaces is uniform and intact, and the sealing and corrosion protection performance is reliable.

[0034] In another embodiment, a chemical composition slurry for enhancing the sealing performance of offshore wind turbine flanges is provided, comprising the following components by mass fraction: Alkenyl resin: 40.0%-68.45%; Thiol-based crosslinking agent: 15.0%-28.8%; Piezoelectric sensing filler: 15.0%-25.0%; Electrochemical initiator: 0.5%-2.0%; Interface coupling agent: 1.0%-4.0%; Conductive additives: 0.05%-0.2%.

[0035] This embodiment provides a chemical composition slurry specifically designed for the aforementioned construction method, with the mass fractions of its components carefully proportioned and optimized. The alkenyl resin, as a reactive prepolymer, constitutes the main framework of the cured polymer network, and its wide content range of 40.0% to 68.45% allows for adjustment based on the requirements for coating flexibility and final mechanical strength. The mass fraction of the thiol-based crosslinking agent is controlled between 15.0% and 28.8%, ensuring an appropriate reactive equivalence ratio with the alkenyl resin, enabling the formation of a dense three-dimensional crosslinked network through efficient "thiol-alkene" click chemistry. The piezoelectric sensing filler is present in a significant proportion of 15.0% to 25.0%, a range that ensures the slurry generates a sufficiently strong piezoelectric signal for monitoring under preload, effectively triggering initial setting reactions in localized areas without negatively impacting the initial flowability and final mechanical properties of the slurry.

[0036] As a key component for initiating deep curing, the electrochemical initiator's content is limited to a relatively low range of 0.5% to 2.0%. This is sufficient to generate the necessary concentration of active free radicals to initiate full polymerization when DC voltage is applied, while avoiding side reactions or storage stability issues that may arise from excessive initiator. The proportion of the interface coupling agent is set at 1.0% to 4.0%. This content is sufficient to form a strong chemical bond at the interface between the slurry and the metal flange, significantly improving adhesion while having minimal impact on the overall system viscosity. The conductive additive is added in trace amounts of 0.05% to 0.2%. Its main function is to moderately adjust the conductivity of the slurry, ensuring a uniform distribution of electric field and current during the electrochemical curing step, thereby initiating uniform deep curing. However, excessive amounts may impair the insulation and corrosion resistance of the cured protective layer.

[0037] Furthermore, the alkenyl resin is trimethylolpropane triallyl ether, the thiol-based crosslinking agent is pentaerythritol tetra(3-mercaptopropionate), the piezoelectric sensing filler is barium titanate, the electrochemical initiator is tetrabutylammonium hexafluorophosphate, the interfacial coupling agent is (3-mercaptopropyl)trimethoxysilane, and the conductive additive is graphene nanosheets.

[0038] In this slurry system, the specific chemical selection of each component is crucial to achieving its intended function. Trimethylolpropane triallyl ether was chosen as the alkenyl resin because its molecule contains multiple allyl ether bonds, resulting in high reactivity and a stable network structure after curing. Pentaerythritol tetra(3-mercaptopropionate) was selected as the thiol-based crosslinking agent; its four functionalities facilitate the formation of a high-density crosslinking network, thereby endowing the protective layer with excellent mechanical strength and dielectric resistance. Barium titanate was chosen as the piezoelectric material due to its excellent piezoelectric properties and chemical stability, enabling it to reliably generate and maintain charge under flange preload. Tetrabutylammonium hexafluorophosphate was specified as the electrochemical initiator because of its good solubility in organic systems and its ability to undergo an efficient and clean oxidation reaction at the anolyte under DC voltage, generating the cationic free radicals necessary for polymerization initiation. The interfacial coupling agent used is (3-mercaptopropyl)trimethoxysilane. The methoxysilane group at one end of its molecule can hydrolyze and form a strong Si-O-Me covalent bond with the metal matrix, while the thiol group at the other end can directly participate in the thiol-olefin polymerization reaction, thus achieving a "molecular bridge" between the protective layer and the matrix. Graphene nanosheets are chosen as the conductive additive because of their extremely high specific surface area and conductivity. A very low addition amount can effectively construct charge transport pathways, and their sheet-like structure can also enhance the barrier properties of the cured coating to a certain extent.

[0039] For example, this disclosure provides a specific construction method: S1. Apply a chemical composition slurry to the flange connection surface, wherein the chemical composition slurry comprises an alkenyl resin, a thiol-based crosslinking agent, a piezoelectric sensing filler, and an electrochemical initiator: First, weigh each component according to the following mass fractions: Alkenyl resin: 53.625%; Thiol-based crosslinking agent: 22.5%; Piezoelectric sensing filler: 20.0%; Electrochemical initiator: 1.25%; Interface coupling agent: 2.5%; Conductive additive: 0.125%.

[0040] Preparation process: Pre-dispersion: The alkenyl resin was placed in a planetary mixer at 25°C. Barium titanate, tetrabutylammonium hexafluorophosphate, and graphene nanosheets were added while stirring at 400 rpm.

[0041] Homogenization: Speed ​​up to 2000 rpm, high shear dispersion for 45 min, while simultaneously turning on vacuum for degassing.

[0042] Final mixing and degassing: Reduce the speed to 650 rpm and slowly add the thiol-based crosslinking agent and interfacial coupling agent dropwise. Continue stirring for 22 min and maintain vacuum degassing to obtain the chemical composition slurry.

[0043] Substrate preparation and coating: The flange connection surface was sandblasted to Sa2.5 level, the surface roughness R_z was controlled to be 75μm, and then cleaned with anhydrous ethanol.

[0044] The slurry is evenly applied to the flange connection surface, and the wet film thickness is controlled to be 450μm.

[0045] S2. Align the two flange connecting faces and apply pre-tightening force to close and tighten them: Install a temporary insulating sleeve between the bolt and the flange hole to align the two flanges.

[0046] Apply preload to 40% of the final design torque.

[0047] S3. Monitor the piezoelectric signal generated by the piezoelectric sensing filler in the chemical composition slurry under the preload, and determine the uniformity of the preload and the initial setting state of the slurry based on the piezoelectric signal: Connect the adaptive curing control system to the two flange sections and switch to monitoring mode.

[0048] The piezoelectric signal is monitored in real time. When the signal fluctuation rate is found to be less than 5% within a 30-second period, it is determined that the initial solidification is complete.

[0049] S4. Apply a DC voltage between the two flange connection surfaces to initiate the curing of the chemical composition slurry: The system switches to curing mode, applying a constant DC voltage of 11.5 V between the two flange segments.

[0050] Maintain this voltage for 135 seconds to allow the slurry to fully cure.

[0051] After steps S5 and S4 are completed, apply the final design torque: Remove the control system and temporary insulating sleeve.

[0052] Apply 100% of the final design torque.

[0053] The above embodiments are only used to illustrate the technical solutions of this disclosure, and are not intended to limit it. Although this disclosure has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this disclosure, and should all be included within the protection scope of this disclosure.

Claims

1. A method for constructing an anti-corrosion protective layer to enhance the sealing performance of offshore wind turbine flanges, characterized in that, Includes the following steps: S1. Apply a chemical composition slurry to the flange connection surface, wherein the chemical composition slurry comprises an alkenyl resin, a thiol-based crosslinking agent, a piezoelectric sensing filler, and an electrochemical initiator; S2. Place the two flange connecting faces together and apply preload; S3. Monitor the piezoelectric signal generated by the piezoelectric sensing filler in the chemical composition slurry under the pre-tightening force, and determine the uniformity of the pre-tightening force and the initial setting state of the slurry based on the piezoelectric signal; S4. Apply a DC voltage between the two flange connection surfaces to initiate the curing of the chemical composition slurry; After steps S5 and S4 are completed, the final design torque is applied.

2. The construction method according to claim 1, characterized in that, The alkenyl resin is trimethylolpropane triallyl ether, the thiol-based crosslinking agent is pentaerythritol tetra(3-mercaptopropionate), the piezoelectric sensing filler is barium titanate, and the electrochemical initiator is tetrabutylammonium hexafluorophosphate.

3. The construction method according to claim 1, characterized in that, The chemical composition slurry further comprises an interface coupling agent and a conductive additive, wherein the interface coupling agent is (3-mercaptopropyl)trimethoxysilane and the conductive additive is graphene nanosheets.

4. The construction method according to claim 1, characterized in that, In step S1, the wet film thickness of the chemical composition slurry coating is 300-600 μm.

5. The construction method according to claim 1, characterized in that, Before applying the preload in S2, a temporary insulating sleeve is used between the bolt and the flange hole to ensure electrical isolation between the two flange segments. The preload is 30%-50% of the final design torque.

6. The construction method according to claim 1, characterized in that, In step S3, an adaptive curing control system with an integrated high-impedance voltage monitoring unit is used to monitor the piezoelectric signal.

7. The construction method according to claim 6, characterized in that, In step S3, the criterion for determining whether the piezoelectric signal reaches a stable threshold is that the fluctuation rate of the piezoelectric signal is less than 5% within a 30s period.

8. The construction method according to claim 1, characterized in that, In step S4, the range of the DC voltage is 8.0-15.0V, and the duration of applying the DC voltage is 90-180s.

9. A chemical composition slurry for enhancing the sealing performance of offshore wind turbine flanges, characterized in that, Components containing the following mass fractions: Alkenyl resin: 40.0%-68.45%; Thiol-based crosslinking agent: 15.0%-28.8%; Piezoelectric sensing filler: 15.0%-25.0%; Electrochemical initiator: 0.5%-2.0%; Interface coupling agent: 1.0%-4.0%; Conductive additives: 0.05%-0.2%.

10. The chemical composition slurry according to claim 9, characterized in that, The alkenyl resin is trimethylolpropane triallyl ether, the thiol-based crosslinking agent is pentaerythritol tetra(3-mercaptopropionate), the piezoelectric sensing filler is barium titanate, the electrochemical initiator is tetrabutylammonium hexafluorophosphate, the interfacial coupling agent is (3-mercaptopropyl)trimethoxysilane, and the conductive additive is graphene nanosheets.

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