Interface reinforced composite stainless steel substrate for repairing wading building curved surface and preparation method thereof

Abstract

The application belongs to the technical field of water-related building repair, and particularly relates to an interface-enhanced composite stainless steel substrate for water-related building curved surface repair and a preparation method thereof. The preparation method comprises the following steps: (1) etching the repair side surface of the stainless steel substrate to form scratches on the repair side surface; (2) placing the stainless steel substrate treated in step (1) in an alkaline silicate electrolyte containing sodium fluoride, and applying a pulse voltage to form a porous ceramic transition layer; (3) immersing the repair side surface of the stainless steel substrate treated in step (2) in a pre-hydrolyzed silane solution, and obtaining a silane interface modification layer after the immersion; and (4) coating epoxy resin, curing and cooling to obtain the interface-enhanced composite stainless steel substrate for water-related building curved surface repair. The interface-enhanced composite stainless steel substrate for water-related building curved surface repair has good curved surface adaptability and can reduce the construction difficulty of complex curved surface parts.

Description

Technical Field

[0001] This invention belongs to the field of water-related building repair technology, specifically relating to an interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings and its preparation method. Background Technology

[0002] Water-related structures, such as bridge piers of cross-sea bridges, overflow surfaces of reservoir dams, lock chamber walls of ship locks, and port and wharf structures, are prone to surface erosion, exposed reinforcement, cracks, and localized spalling due to environmental factors such as water erosion, alternating wet and dry conditions, salt spray corrosion, freeze-thaw cycles, and chloride erosion during long-term service. For these damaged areas, stainless steel plates are often used as external repair substrates or permanent formwork. High-performance mortar, resin-based repair materials, or other cementitious repair materials are filled or injected between the stainless steel plate and the concrete surface to be repaired. This creates a composite repair system where the stainless steel plate, repair material layer, and original concrete structure work together to restore the structure's appearance, protective performance, and durability.

[0003] In this type of repair system, the stainless steel plate is typically placed on the outer side of the concrete structure to be repaired, with the side facing the concrete being repaired serving as the repair side or bonding side. Subsequent repair materials are primarily located between this repair side and the surface of the concrete to be repaired. Therefore, the stainless steel substrate not only needs to possess sufficient rigidity and erosion resistance, but also needs to be able to adapt to changes in the curvature of the concrete surface to be repaired, and maintain stable interfacial bonding performance in water-filled or high-humidity environments.

[0004] However, in practical engineering applications, existing stainless steel repair substrate technology has the following significant technical drawbacks: First, there is a contradiction between surface adaptability and structural stiffness. The surfaces of water-related structures are often non-standard and complex curved surfaces, such as round-ended bridge piers, irregularly shaped columns, and the overflow surfaces of hyperbolic arch dams. While stainless steel plates of conventional thickness offer good overall stiffness and erosion resistance, their ability to conform to shapes during on-site cold bending is limited, making it difficult to achieve a tight fit with complex curved surfaces and prone to springback, gaps, or localized warping. Using thinner stainless steel plates, although surface adaptability is improved, they are susceptible to bulging, buckling, or localized deformation under grouting pressure, water flow impact, or construction disturbances, making it difficult to guarantee the smoothness and long-term stability of the repaired surface. Although existing technologies include methods to improve the flexibility of metal plates through grooving, indentation, or localized thinning, simple physical thinning creates stress concentration areas at the root of the groove, and the exposed metal substrate at the bottom of the groove is more prone to pitting corrosion, crevice corrosion, or fatigue damage in humid, chlorine-containing, or underwater environments.

[0005] Secondly, the water-resistant bonding performance of the heterogeneous interface on the repair side is insufficient. Stainless steel surfaces are typically dense and smooth with high chemical inertness. The bonding between stainless steel and epoxy resin, mortar, or other repair materials often relies on mechanical bonding formed through methods such as sandblasting, roughening, and embossing. In dry environments, this mechanical bonding can maintain a certain level of adhesion; however, in wet or high-humidity environments, water molecules easily penetrate along the interface between the stainless steel surface and the organic resin layer, gradually weakening the physical adsorption between the metal surface and the resin, leading to water-induced delamination at the interface. The water-resistant bonding performance referred to in this article mainly refers to the water-resistant interface bonding performance between the metal substrate or its surface transition layer on the repair side of the composite substrate and the epoxy resin layer. It also includes the stability of the composite interface formed between the epoxy resin layer and the subsequently filled or infused repair materials. Among these, the durability of the internal interface between the metal substrate surface and the epoxy resin layer is crucial to the long-term service performance of the composite substrate.

[0006] Third, existing surface treatment methods lack stable chemical bonding mechanisms. Current treatments for stainless steel repair substrates primarily focus on physical roughening, such as sandblasting, roughening, grinding, or embossing. These methods mainly aim to increase surface roughness and mechanical adhesion, but they struggle to establish stable chemical bonds between the metal substrate and the organic resin layer. While some coating modification methods can improve initial adhesion to some extent, the bonding strength of ordinary organic coatings on stainless steel surfaces is limited, and they are prone to localized damage during bending, handling friction, or water erosion, making it difficult to simultaneously meet the requirements of corrosion protection, interfacial bonding, and conformal surface treatment.

[0007] In summary, the existing technology lacks a composite stainless steel substrate material that can meet the requirements of on-site construction of complex curved surfaces and maintain stable interfacial bonding performance (water-resistant adhesion between the surface of the stainless steel substrate facing the concrete to be repaired and the epoxy resin layer on its surface) in water-contaminated or high-humidity environments.

[0008] Therefore, there is a need to provide an improved technical solution that addresses the shortcomings of the existing technology. Summary of the Invention

[0009] The purpose of this invention is to provide an interface-reinforced composite stainless steel substrate for the repair of curved surfaces in water-related buildings and its preparation method, so as to help solve or improve the problems of existing stainless steel substrates being unable to meet the requirements of on-site construction of complex curved surfaces and poor water-resistant bonding performance.

[0010] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing an interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings, comprising the following steps: (1) etching the repair side surface of the stainless steel substrate to form a groove on the repair side surface; (2) placing the stainless steel substrate obtained in step (1) in an alkaline silicate electrolyte containing sodium fluoride, applying a pulse voltage to form a porous ceramic transition layer at least on the repair side surface and within the groove; (3) immersing the repair side surface of the stainless steel substrate obtained in step (2) in a pre-hydrolyzed silane solution, and drying it after immersion to obtain a silane interface modification layer; (4) coating the repair side surface of the stainless steel substrate obtained in step (3) with epoxy resin, curing, and cooling to obtain the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings.

[0011] Preferably, in step (1), the depth of the groove is 40%-60% of the thickness of the stainless steel substrate, and the width of the groove is 0.2-0.3 mm; the etching method is laser etching.

[0012] Preferably, the notches include transverse notches and longitudinal notches, and the angle between the transverse notches and the longitudinal notches is 60°-90°; the grid cells formed by the transverse notches and the longitudinal notches are rhomboid or square, and the side length L of the grid cells and the minimum radius of curvature R of the concrete surface to be repaired satisfy the geometric constraint relationship: L≤0.05R.

[0013] Preferably, the electrolyte comprises sodium silicate, sodium fluoride, and potassium hydroxide; the pulse voltage is applied for 10-20 minutes.

[0014] Preferably, the concentration of sodium silicate is 8-12 g / L, the concentration of sodium fluoride is 0.5-1.5 g / L, and the concentration of potassium hydroxide is 1-3 g / L; the pulse voltage is 350-450 V, and the current density is 5-10 A / dm³. 2 The frequency is 600Hz, and the duty cycle is 15%-25%; the thickness of the porous ceramic transition layer is 10-30μm; the porosity of the porous ceramic transition layer is 20%-30%; the depth h of the groove and the thickness t of the porous ceramic transition layer satisfy the following condition: h≥20t.

[0015] Preferably, the pre-hydrolyzed silane solution is obtained by mixing a silane coupling agent and a solvent, adjusting the pH to 3.5-5.5, and then hydrolyzing and activating for 20-40 minutes; the drying temperature is 100-120℃.

[0016] Preferably, the silane coupling agent is selected from at least one of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane; the solvent is a mixed solution of ethanol and water; the mass of the silane coupling agent is 1.0%-3.0% of the sum of the masses of the silane coupling agent and the solvent; and the grafting coverage of the silane coupling agent on the surface of the porous ceramic transition layer is 0.5~2.0 g / m². 2 .

[0017] Preferably, in step (4), epoxy resin is used to fill the grooves and penetrate into the pores of the porous ceramic transition layer by using a scraping process and / or a negative pressure assisted process; the curing temperature is 80-90℃; and the cooling method is gradient cooling.

[0018] Preferably, the gradient cooling includes: first cooling to 50°C at a rate of 2-3°C / min, holding at 50°C for 10-20min, and then naturally cooling to room temperature.

[0019] Preferably, before step (2), a step of rolling and leveling the substrate obtained in step (1) is included; the stainless steel substrate is a 201 stainless steel plate and the thickness of the stainless steel substrate is 1-5mm.

[0020] This invention also provides an interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings, which adopts the following technical solution: an interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings, wherein the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings is prepared by the method described above; the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings includes a stainless steel substrate, grooves disposed on the repair side surface of the stainless steel substrate, a porous ceramic transition layer formed on at least the repair side surface of the stainless steel substrate and the inner wall and bottom of the grooves, a silane interface modification layer grafted onto the surface of the porous ceramic transition layer, and an epoxy resin layer disposed on the repair side surface of the stainless steel substrate and filling the grooves and the pores of the porous ceramic transition layer. Beneficial effects

[0021] (1) The interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings of the present invention has good adaptability to curved surfaces, which can reduce the construction difficulty of complex curved surfaces. By setting grooves on the side of the substrate facing the concrete to be repaired, the overall stiffness of the substrate can be discretized, so that the thicker substrate can still bend and fit the surface of the concrete to be repaired while maintaining a certain resistance to erosion and deformation. In particular, by reasonably controlling the groove depth and grid unit size, the stainless steel substrate can adapt to complex curved surfaces with R < 500mm (R represents the minimum radius of curvature of the surface of the concrete to be repaired, such as the minimum local bending radius of curved structures such as the outer wall of a circular or round-ended bridge pier, or the overflow surface of a dam), reducing the elastic rebound, warping and voiding after bending, thereby reducing the difficulty of on-site construction and the dependence on anchor bolts.

[0022] (2) This invention can improve the water-resistant interfacial bonding performance of the repair side surface of the composite substrate. The epoxy resin layer in this invention is preferably disposed on the side surface of the substrate facing the concrete to be repaired, i.e., the repair side surface, rather than necessarily on both sides of the substrate. By constructing a composite interfacial reinforcement system of "macro-anchoring (grooves) + micro-anchoring (pores in the porous ceramic transition layer) + molecular chemical bonding (silane interface modification layer)," the bonding strength and water resistance stability between the repair side surface of the substrate and the epoxy resin layer can be significantly improved. In practical repair applications, the epoxy resin layer faces the concrete structure to be repaired and can further bond with mortar, resin-based repair materials, or other cementitious repair materials filled or injected between the composite substrate and the concrete structure to be repaired, thereby forming a stable composite repair interface and reducing the risk of interface peeling, detachment, and peeling in water-related environments.

[0023] (3) This invention can improve the corrosion protection performance of the grooved area. Traditional mechanical grooving or laser etching will destroy the passivation film on the stainless steel surface, making the bottom of the grooved area a weak corrosion area. This invention uses micro-arc oxidation technology to generate a porous ceramic transition layer in situ on the repair side surface of the substrate, the inner wall of the groove, and the bottom of the groove, thereby forming a corrosion barrier in the grooved area, reducing the risk of pitting corrosion, crevice corrosion and interface corrosion at the bottom of the grooved area in humid, chlorine-containing or underwater environments, and realizing the integration of structural processing and corrosion protection.

[0024] (4) The process parameters of this invention have synergistic matching. This invention is not a simple superposition of etching, micro-arc oxidation, silane modification and epoxy resin coating processes, but rather achieves the substrate simultaneously possessing surface conformability, interface enhancement and etching corrosion resistance through the synergistic matching of the etching depth, the thickness of the porous ceramic transition layer, the pore structure and the epoxy resin penetration performance. For example, the pore structure of the porous ceramic transition layer can provide space for epoxy resin penetration, the silane interface modification layer can enhance the chemical bond between the porous ceramic transition layer and the epoxy resin layer, and the gradient cooling process can release the residual thermal stress generated by the difference in thermal expansion coefficients between the metal substrate and the epoxy resin layer, thereby reducing the risk of interface microcracks. Attached Figure Description

[0025] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Wherein: Figure 1 This is a schematic diagram of the etched structure on the repair side surface of the substrate provided in an embodiment of the present invention.

[0026] Figure 2 for Figure 1 A schematic diagram of the cross-sectional structure obtained by cutting along line AA; where T represents the thickness of the stainless steel substrate, h represents the groove depth, and w represents the groove width. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0028] The present invention will now be described in detail with reference to embodiments. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0029] This invention addresses the challenges of existing stainless steel repair substrates in simultaneously achieving conformal construction of complex curved surfaces, corrosion protection of scored areas, and water-resistant bonding performance at the interface in water-related environments. It provides an interface-reinforced composite stainless steel substrate for repairing curved surfaces in water-related buildings, along with its preparation method. In this invention, the surface of the stainless steel substrate facing the concrete structure to be repaired during use is defined as the repair side surface. This repair side surface is used to form a composite repair interface with subsequent filling or grouting of mortar, resin-based repair materials, or other cementitious repair materials.

[0030] The preparation method of the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings according to embodiments of the present invention includes the following steps: (1) etching the repair side surface of the stainless steel substrate to form a groove on the repair side surface; (2) placing the stainless steel substrate obtained in step (1) in an alkaline silicate electrolyte containing sodium fluoride and applying a pulse voltage to form a porous ceramic transition layer at least on the repair side surface and within the groove; (3) immersing the repair side surface of the stainless steel substrate obtained in step (2) in a pre-hydrolyzed silane solution, drying it after immersion, and grafting the silane coupling agent onto the surface of the porous ceramic transition layer to obtain a silane interface modified layer; (4) coating the repair side surface of the stainless steel substrate obtained in step (3) with epoxy resin, so that the epoxy resin covers the repair side surface, fills the groove, and penetrates into the pores of the porous ceramic transition layer. After curing and cooling, the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings is obtained. Unless otherwise stated, the term "substrate surface" in the following invention mainly refers to the repair side surface of the substrate.

[0031] In step (1), the scoring helps to discretize the overall stiffness of the stainless steel substrate, reducing the bending resistance of the stainless steel substrate during the curved surface bonding process, and enabling the stainless steel substrate to adapt to the curvature changes of the concrete structure surface to be repaired. In step (2), by placing the stainless steel substrate in an alkaline silicate electrolyte containing sodium fluoride and applying a pulse voltage, the instantaneous high temperature generated by the micro-arc discharge can be used to convert the metal elements on the surface of the stainless steel substrate into ceramic oxides in situ, thereby forming a porous ceramic transition layer on the repair side surface, the inner wall of the scoring, and the bottom of the scoring groove. During the immersion micro-arc oxidation process, other exposed surfaces of the substrate can also form ceramic oxide layers simultaneously, but the functional areas used for interface enhancement and scoring corrosion protection in this invention are mainly the repair side surface and the scoring area. The porous ceramic transition layer in the scoring area does not require its porosity to be less than that of the area outside the scoring, but rather emphasizes that the inner wall of the scoring and the bottom of the groove can form a continuous and complete ceramic covering layer to avoid the bottom of the scoring groove being exposed metal substrate and becoming a weak corrosion area. In step (3), the silane interface modification layer mainly exists in the form of a molecular graft layer or a thin-layer interface modification layer on the pore walls and surface of the porous ceramic transition layer. Its thickness is much smaller than the pore size of the porous ceramic transition layer, so it will not substantially block the open pores of the porous ceramic transition layer. The silanol groups formed after the hydrolysis of the silane coupling agent can undergo a condensation reaction with the hydroxyl groups on the surface of the porous ceramic transition layer, and the organic end groups can react with or be compatible with the epoxy resin layer, thereby establishing a stable chemical connection between the porous ceramic transition layer and the epoxy resin layer. In step (4), the epoxy resin layer is set on the repair side surface of the substrate, rather than necessarily on both sides of the substrate; the epoxy resin layer is used to fill the grooves and pores of the porous ceramic transition layer, and also to form a bond with the repair material layer between the stainless steel substrate and the concrete structure to be repaired during actual repair.

[0032] In a preferred embodiment of the preparation method of the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings of the present invention, in step (1), the depth of the groove is 40%-60% (e.g., 40%, 45%, 50%, 55% or 60%) of the thickness of the metal substrate plate, the width of the groove is 0.2-0.3 mm, and the etching method is laser etching. The groove is in the form of a grid, which refers to a continuous grid structure formed by the intersection of transverse grooves extending along the first direction and longitudinal grooves extending along the second direction; the transverse grooves and longitudinal grooves together divide the repair side surface of the substrate into multiple continuously arranged grid units. If the groove depth is too small, the remaining stiffness of the substrate is too large, and a large elastic rebound stress is easily generated when it is applied to a curved surface with a small radius of curvature, resulting in a gap or warping between the substrate and the surface of the concrete to be repaired; if the groove depth is too large, the remaining effective cross section at the bottom of the groove is too thin, and fatigue cracking or local fracture is easily caused under construction, handling, bending and bonding or water flow impact. Therefore, controlling the groove depth to 40%-60% of the thickness of the metal substrate helps to achieve a balance between the surface conformability and the remaining load-bearing capacity.

[0033] In a preferred embodiment of the preparation method of the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings according to the present invention, the notches include transverse notches and longitudinal notches, and the angle between the transverse and longitudinal notches is 60°-90° (e.g., 60°, 70°, 80° or 90°). When the angle between the transverse and longitudinal notches is 90°, a square grid unit can be formed; when the angle between the transverse and longitudinal notches is less than 90° and not less than 60°, a rhomboid grid unit can be formed. By setting transverse and longitudinal notches, the stainless steel substrate can have a certain bending adaptability in different directions, thus making it suitable for complex curved surface repair scenarios such as round-ended bridge piers, irregularly shaped piers, and dam overflow surfaces.

[0034] In a preferred embodiment of the method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings according to the present invention, the grid units formed by the transverse and longitudinal grooves are rhomboid or square. The side length L of the grid unit satisfies the geometric constraint relationship with the minimum radius of curvature R of the concrete surface to be repaired: L≤0.05R. Here, R represents the minimum radius of curvature of the concrete surface to be repaired, which can be determined based on the design drawings of the component to be repaired, on-site three-dimensional scanning data, curvature template fitting measurement results, or other surface measurement methods. If L is too large, a single grid unit will not be able to fully deform with the curved surface, easily resulting in localized broken-line fitting, springback, or detachment. If L is too small, the number of grooves will be too large, potentially weakening the effective load-bearing section of the substrate and increasing processing costs, resin filling defects, and the risk of stress concentration in the grooved area. Therefore, controlling L to be no greater than 0.05R helps to balance the surface conformability, structural integrity, and processing feasibility.

[0035] In a preferred embodiment of the method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings according to the present invention, in step (2), the electrolyte comprises sodium silicate, sodium fluoride, and potassium hydroxide; the applied pulse voltage is applied for 10-20 min (e.g., 10 min, 13 min, 16 min, or 20 min). Further, the concentration of sodium silicate is 8-12 g / L (e.g., 8 g / L, 10 g / L, or 12 g / L), the concentration of sodium fluoride is 0.5-1.5 g / L (e.g., 0.5 g / L, 1 g / L, or 1.5 g / L), and the concentration of potassium hydroxide is 1-3 g / L (e.g., 1 g / L, 2 g / L, or 3 g / L); the pulse voltage is 350-450 V (e.g., 350 V, 400 V, or 450 V), and the current density is 5-10 A / dm³. 2 (For example, 5A / dm) 2 8A / dm 2 or 10A / dm 2 The frequency is 600Hz, and the duty cycle is 15%-25% (e.g., 15%, 18%, 20%, 22% or 25%); the thickness of the porous ceramic transition layer is 10-30μm (e.g., 10μm, 15μm, 20μm, 25μm or 30μm), and the porosity of the porous ceramic transition layer is 20%-30% (e.g., 20%, 23%, 25%, 28% or 30%); the indentation depth h and the thickness t of the porous ceramic transition layer satisfy h≥20t.

[0036] Porosity refers to the percentage of the total pore volume in the porous ceramic transition layer. The porosity of the porous ceramic transition layer can be controlled by adjusting the concentrations of sodium silicate, sodium fluoride, and potassium hydroxide in the electrolyte, as well as the pulse voltage, current density, frequency, duty cycle, and processing time. The "directional control" in this invention refers to adjusting the micro-arc discharge intensity, oxide film growth rate, local dissolution rate, and gas evolution behavior by matching the electrolyte composition and electrical parameters, thereby controlling the thickness, porosity, and pore size distribution of the porous ceramic transition layer. This invention, through a specific voltage window and the combination with a fluorinated alkaline silicate electrolyte system, enables the porous ceramic transition layer to form an open pore structure that allows epoxy resin to penetrate. This open pore structure can match the flowability and penetration capacity of the epoxy resin; if the pore structure is too dense, the epoxy resin will have difficulty penetrating effectively and will only form a surface adsorption layer; if the pore structure is too loose, the mechanical integrity and load-bearing capacity of the porous ceramic transition layer itself may decrease. The pores are those in the porous ceramic transition layer, not those in the epoxy resin material itself.

[0037] In a preferred embodiment of the preparation method of the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings of the present invention, in step (3), the pre-hydrolyzed silane solution is obtained by mixing a silane coupling agent and a solvent, adjusting the pH to 3.5-5.5 (e.g., 3.5, 4, 4.5, 5 or 5.5), and then hydrolyzing and activating it at 20-30°C (e.g., 20°C, 23°C, 26°C or 30°C) for 20-40 min (e.g., 20 min, 25 min, 30 min, 35 min or 40 min); the solvent is a mixed solution of ethanol and water, wherein the mass ratio of ethanol to water is (80-95):(5-20) (e.g., 80:5, 80:10, 80:20, 88:5, 88:20, 88:15, 95:5, 95:10 or 95:20), preferably 90:10. The repaired side surface of the substrate obtained by step (2) is immersed in a pre-hydrolyzed silane solution for 3-10 min (e.g., 3 min, 5 min, 7 min or 10 min). After immersion, the substrate is removed and dried at a temperature of 100-120°C (e.g., 100°C, 105°C, 110°C, 115°C or 120°C).

[0038] The drying step not only removes the solvent but also facilitates the dehydration condensation reaction between the silanol groups generated from the hydrolysis of the silane coupling agent and the hydroxyl groups on the surface of the porous ceramic transition layer, thereby converting physical adsorption into more stable chemical grafting. The grafting coverage of the silane coupling agent on the surface of the porous ceramic transition layer is 0.5-2.0 g / m². 2 (For example, 0.5g / m 2 1.0g / m 2 1.5g / m 2 Or 2.0g / m 2 The grafting coverage refers to the mass of silane coupling agent per square meter of porous ceramic transition layer surface after impregnation, drying, and retention. If this grafting coverage is too low, it is difficult to form an effective interfacial bridging effect; if the grafting coverage is too high, it may form an excessively thick organic enrichment layer, which in turn affects the penetration of epoxy resin into the pores of the porous ceramic transition layer and the interfacial stability.

[0039] In a preferred embodiment of the preparation method of the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings according to the present invention, the silane coupling agent is selected from at least one of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, and γ-methacryloyloxypropyltrimethoxysilane. One end of the above-mentioned silane coupling agent can undergo a condensation reaction with the hydroxyl groups on the surface of the porous ceramic transition layer, and the other end can react or compatibly bond with the epoxy resin layer, thereby enhancing the interfacial bonding performance between the porous ceramic transition layer and the epoxy resin layer.

[0040] In a preferred embodiment of the preparation method of the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings according to the present invention, in step (4), epoxy resin is used to fill the grooves and penetrate into the pores of the porous ceramic transition layer using a scraping process and / or a negative pressure assisted process. When using the scraping process, epoxy resin is applied to the repair side surface of the substrate, and a rubber scraper is used to scrape it back and forth 1-3 times along the transverse and longitudinal directions, allowing the epoxy resin to enter the grooves and the pores of the porous ceramic transition layer, while simultaneously expelling air from the pores. When using the negative pressure assisted process, the substrate coated with epoxy resin is placed in a negative pressure environment with a negative pressure of -0.06 MPa to -0.09 MPa, maintained for 2-5 minutes, and then restored to normal pressure, allowing the epoxy resin to further penetrate into the pores of the porous ceramic transition layer under the action of pressure difference. The "pores" or "micropores" referred to in this invention refer to the open pores in the porous ceramic transition layer, not the pores of the epoxy resin material itself.

[0041] In a preferred embodiment of the preparation method of the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings according to the present invention, in step (4), the epoxy resin curing temperature is 80-90℃ (e.g., 80℃, 83℃, 86℃, or 90℃). After curing, a gradient cooling process is performed, which includes: first cooling to 50℃ at a rate of 2-3℃ / min, holding at 50℃ for 10-20min (e.g., 10min, 13min, 16min, or 20min), and then naturally cooling to room temperature. Through this gradient cooling process, the residual thermal stress generated by the difference in thermal expansion coefficients between the metal substrate and the epoxy resin layer can be released, reducing the risk of interface microcracks during the curing and cooling process.

[0042] In a preferred embodiment of the method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings according to the present invention, step (2) is further included by performing a roll-pressing leveling process on the substrate obtained in step (1). The stainless steel substrate is a 201 stainless steel plate with a thickness of 1-5 mm. The laser etching in step (1) may introduce residual thermal stress locally on the stainless steel substrate and cause the plate to warp. If the leveling process is not performed, the stainless steel substrate may have difficulty maintaining a uniform electrode spacing in the electrolyte in step (2), which may lead to uneven thickness of the porous ceramic transition layer. The electrode spacing in the present invention refers to the distance between the stainless steel substrate, which serves as the anode, and the cathode during the micro-arc oxidation process. By performing the roll-pressing leveling process, the stainless steel substrate can maintain a relatively stable and uniform electric field distribution in the electrolyte, thereby improving the consistency of the growth of the porous ceramic transition layer.

[0043] This invention also proposes an interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings. The interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings is prepared using the method described above. The interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings includes a stainless steel substrate, grooves disposed on the repair side surface of the stainless steel substrate, a porous ceramic transition layer formed on at least the repair side surface, the inner wall of the grooves, and the bottom of the grooves, a silane interface-modified layer grafted onto the surface of the porous ceramic transition layer, and an epoxy resin layer disposed on the repair side surface and filling the pores of the grooves and the porous ceramic transition layer. In actual use, the epoxy resin layer faces the concrete structure to be repaired and forms a bond with the mortar, resin-based repair material, or other cementitious repair material filled or injected between the composite stainless steel substrate and the concrete structure to be repaired.

[0044] The following detailed description, through specific embodiments, illustrates the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings and its preparation method.

[0045] The main raw materials used in the following examples are sourced from the following sources: 201 stainless steel sheet: Purchased from Taiyuan Iron & Steel (Group) Co., Ltd., grade 201, cold-rolled sheet, with thicknesses of 1.0mm, 2.0mm, and 5.0mm respectively. Before use, cut to the required dimensions according to the example, and clean and dry the surface to be treated with ethanol. It should be noted that commercially available 201 stainless steel sheet meeting the same grade and thickness requirements can also be used as a substitute.

[0046] Sodium silicate: Purchased from Sinopharm Chemical Reagent Co., Ltd., analytical grade, sodium silicate nonahydrate, chemical formula: It is used to prepare alkaline silicate electrolytes.

[0047] Potassium hydroxide: purchased from Sinopharm Chemical Reagent Co., Ltd., analytical grade, KOH content not less than 85%, used to adjust the alkalinity of the electrolyte and improve its conductivity.

[0048] Sodium fluoride: purchased from Sinopharm Chemical Reagent Co., Ltd., analytical grade, with a NaF content of not less than 98%, used to prepare fluorine-containing alkaline silicate electrolyte to promote the formation of porous ceramic transition layer and pore structure regulation during micro-arc oxidation.

[0049] Silane coupling agent KH-560: Purchased from Nanjing Shuguang Chemical Group Co., Ltd., model KH-560, chemical name γ-glycidyl etheroxypropyltrimethoxysilane, industrial grade or reagent grade is acceptable, purity not less than 98%, used to prepare pre-hydrolyzed silane solutions and form a silane interface modification layer on the surface of porous ceramic transition layers.

[0050] Alternative silane coupling agents: γ-aminopropyltriethoxysilane can be KH-550 produced by Nanjing Shuguang Chemical Group Co., Ltd.; γ-methacryloyloxypropyltrimethoxysilane can be KH-570 produced by Nanjing Shuguang Chemical Group Co., Ltd. All of the above silane coupling agents are commercially available products and can be selected according to the reaction end group type of the epoxy resin system.

[0051] Anhydrous ethanol: Purchased from Sinopharm Chemical Reagent Co., Ltd., analytical grade, with an ethanol content of not less than 99.7%, used to prepare ethanol aqueous solution of silane coupling agent and as an organic solvent in the silane pre-hydrolysis process.

[0052] Water: Laboratory-made deionized water with a resistivity of not less than 18 MΩ·cm was used to prepare the electrolyte and silane coupling agent ethanol aqueous solution.

[0053] pH adjuster: Glacial acetic acid, purchased from Sinopharm Chemical Reagent Co., Ltd., analytical grade, is used to adjust the pH of the silane coupling agent ethanol aqueous solution to 3.5-5.5. In practical use, the glacial acetic acid can be pre-prepared into a dilute acetic acid aqueous solution before being added dropwise to avoid excessively high local acidity affecting the hydrolytic stability of the silane.

[0054] E-51 epoxy resin: Purchased from Nantong Xingchen Synthetic Materials Co., Ltd., model E-51, epoxy value 0.48-0.54 mol / 100g, used as the main resin for the epoxy resin layer. E-51 epoxy resin can also be replaced by commercially available bisphenol A type epoxy resin with the same epoxy value range.

[0055] Epoxy curing agent: 650 polyamide curing agent is used, purchased from Tianjin Jindong Tianzheng Fine Chemical Reagent Factory or other commercially available equivalent products, with an amine value of 200±20mgKOH / g, used to formulate a two-component epoxy resin system with E-51 epoxy resin.

[0056] The preparation method of the two-component epoxy resin is as follows: E-51 epoxy resin and 650 polyamide curing agent are mixed at a mass ratio of 100:(40-60), preferably 100:50. The mixture is mechanically stirred at room temperature for 3-5 minutes until the system is homogeneous. After standing for 1-3 minutes to remove some air bubbles, the two-component epoxy resin for coating is obtained. The two-component epoxy resin should be used within 30 minutes of preparation to avoid increased system viscosity, which would affect its penetration into the pores of the scoring and porous ceramic transition layer.

[0057] The pre-hydrolyzed silane solution is prepared as follows: A silane coupling agent, anhydrous ethanol, and deionized water are mixed, with a mass ratio of anhydrous ethanol to deionized water of 90:10. The mass of the silane coupling agent is 2.0% of the total mass of the silane coupling agent, anhydrous ethanol, and deionized water. The pH of the system is then adjusted to 4.5 using a dilute acetic acid aqueous solution, and the mixture is stirred and activated at 20-30℃ for 30 min to obtain the pre-hydrolyzed silane solution. This pre-hydrolyzed silane solution should be used within 4 hours of preparation.

[0058] The alkaline silicate electrolyte is prepared as follows: Sodium silicate, potassium hydroxide, and sodium fluoride are weighed according to the required concentration in the example, and added sequentially to deionized water. The mixture is stirred until completely dissolved to obtain a fluorinated alkaline silicate electrolyte. After preparation, the solution is allowed to stand for 5-10 minutes until the bubbles in the solution are largely eliminated before being used for micro-arc oxidation treatment.

[0059] Example 1 The method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings in this embodiment includes the following steps: (1) Substrate preparation: A 2.0mm thick 201 stainless steel plate was selected and cut into 200mm × 200mm substrates. The side of the substrate facing the concrete structure to be repaired during use was defined as the repair side surface. The repair side surface was etched using a fiber laser to form a grid-like pattern (e.g., Figures 1-2 As shown in the figure, the angle between the transverse and longitudinal grooves is 90°, and the grid unit size is 20mm × 20mm. The grid-like grooves cover the entire repair side surface of the substrate, and adjacent grid units share the corresponding groove boundaries. There are no separate unetched intervals between adjacent grid units. The groove depth (h) is set to 1.0mm, which is 50% of the board thickness (T), and the groove width (w) is 0.25mm. After etching, the substrate is leveled using a multi-roller leveling machine. In this embodiment, the grid unit side length L is 20mm. According to the geometric constraint relationship of L≤0.05R, the composite substrate prepared in this embodiment is suitable for curved surface structures with a minimum radius of curvature R of not less than 400mm on the concrete surface to be repaired.

[0060] (2) Micro-arc oxidation: The stainless steel substrate obtained in step (1) is placed as the anode in an alkaline silicate electrolyte containing sodium fluoride, so that the entire stainless steel substrate is immersed in the electrolyte; the stainless steel substrate is used as the cathode. A 420V pulse voltage, a frequency of 600Hz, a duty cycle of 20%, and a processing time of 15min are used to grow a porous ceramic transition layer in situ on the surface of the stainless steel substrate. The electrolyte composition is: sodium silicate 10g / L, potassium hydroxide 2g / L, and sodium fluoride 1g / L.

[0061] Process phenomena: Fine white micro-arc discharges were observed on the repaired side surface of the substrate, especially on the inner wall of the groove and the bottom of the groove. Since this embodiment uses immersion micro-arc oxidation treatment, other exposed surfaces of the stainless steel substrate can also form a ceramic oxide layer simultaneously; however, the functional areas used for interface enhancement and groove corrosion protection in this embodiment are mainly the repaired side surface of the stainless steel substrate, the inner wall of the groove, and the bottom of the groove.

[0062] Test results: A grayish-white porous ceramic transition layer was formed on the repaired side surface, the inner wall of the groove, and the bottom of the groove on the stainless steel substrate, with complete coverage of the groove bottom. Coating thickness measurement showed the porous ceramic transition layer to be approximately 25 μm thick; porosity measurement showed the porosity to be approximately 25%. The pores are open pores within the porous ceramic transition layer.

[0063] (3) Silane modification: Prepare a 2wt% KH-560 pre-hydrolyzed silane solution. The specific steps are as follows: Mix KH-560, anhydrous ethanol and deionized water, wherein the mass ratio of anhydrous ethanol to deionized water is 90:10, and the mass of KH-560 is 2.0% of the total mass of KH-560, anhydrous ethanol and deionized water; adjust the pH of the system to 4.5 with dilute acetic acid aqueous solution, and stir and hydrolyze at 25℃ for 30 min to obtain the pre-hydrolyzed KH-560 silane solution. Immerse the repair side surface of the stainless steel substrate obtained in step (2) in the pre-hydrolyzed KH-560 silane solution for 5 min; after taking it out, place it in a 110℃ oven for heat treatment for 15 min to graft the silane coupling agent onto the surface of the porous ceramic transition layer to form a silane interface modification layer.

[0064] (4) Resin Composite: E-51 epoxy resin and 650 polyamide curing agent are mixed at a mass ratio of 100:50 and stirred evenly to obtain a two-component epoxy resin. The two-component epoxy resin is coated on the repair side surface of the substrate. A rubber scraper is used to scrape the resin twice along the transverse and longitudinal directions to cover the repair side surface, fill the grooves, and penetrate into the pores of the porous ceramic transition layer, while expelling the air in the pores. The coated substrate is then cured at 85°C for 30 min. After curing, a gradient cooling process is performed, i.e., the temperature is first reduced to 50°C at a rate of 2°C / min, and then kept at 50°C for 15 min. After that, it is naturally cooled to room temperature to obtain the interface-reinforced composite stainless steel substrate for the repair of curved surfaces of water-related buildings.

[0065] The interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings in this embodiment was prepared using the method described above.

[0066] Example 2 The method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings in this embodiment includes the following steps: (1) Substrate preparation: A 1.0mm thick 201 stainless steel plate was selected and cut into 200mm×200mm stainless steel substrates. The side of the stainless steel substrate facing the concrete structure to be repaired was defined as the repair side surface. The repair side surface was etched using a fiber laser to form a bidirectional orthogonal grid pattern, with the angle between the transverse and longitudinal etched lines being 90° and the grid unit size being 7.5mm×7.5mm. The grid pattern covered the entire repair side surface of the stainless steel substrate, with adjacent grid units sharing the corresponding etched boundary and no separate unetched intervals between adjacent grid units. The etched depth was set to 0.45mm, which is 45% of the plate thickness, and the etched width was 0.25mm. After etching, a multi-roller leveling machine was used for leveling. In this embodiment, the side length L of the grid unit is 7.5mm. According to the geometric constraint relationship of L≤0.05R, the composite substrate prepared in this embodiment is suitable for small-radius curved surface structures with a minimum radius of curvature R of not less than 150mm on the concrete surface to be repaired.

[0067] (2) Micro-arc oxidation: The substrate obtained in step (1) is placed as the anode in an alkaline silicate electrolyte containing sodium fluoride, so that the entire substrate is immersed in the electrolyte; a stainless steel plate is used as the cathode. A 380V pulse voltage, a frequency of 600Hz, a duty cycle of 20%, and a processing time of 15min are used to grow a porous ceramic transition layer in situ on the substrate surface. The electrolyte composition is: sodium silicate 10g / L, potassium hydroxide 2g / L, and sodium fluoride 1g / L.

[0068] Process phenomena: Fine white micro-arc discharges were observed on the repaired side surface of the substrate, especially on the inner wall of the groove and the bottom of the groove. Since this embodiment uses immersion micro-arc oxidation treatment, other exposed surfaces of the substrate can also form a ceramic oxide layer simultaneously; however, the functional areas used for interface enhancement and groove corrosion protection in this embodiment are mainly the repaired side surface of the substrate, the inner wall of the groove, and the bottom of the groove.

[0069] Test results: A grayish-white porous ceramic transition layer was formed on the repaired side surface of the substrate, the inner wall of the groove, and the bottom of the groove, with complete coverage of the groove bottom. Coating thickness measurement showed the porous ceramic transition layer to be approximately 20 μm thick; porosity measurement showed the porosity to be approximately 22%. The pores are open pores within the porous ceramic transition layer, not pores within the epoxy resin material itself.

[0070] (3) Silane modification: Prepare a 2wt% KH-560 pre-hydrolyzed silane solution. The specific steps are as follows: Mix KH-560, anhydrous ethanol and deionized water, wherein the mass ratio of anhydrous ethanol to deionized water is 90:10, and the mass of KH-560 is 2.0% of the total mass of KH-560, anhydrous ethanol and deionized water; adjust the pH of the system to 4.5 with dilute acetic acid aqueous solution, and stir and hydrolyze at 25℃ for 30 min to obtain the pre-hydrolyzed KH-560 silane solution. Immerse the repaired side surface of the stainless steel substrate obtained in step (2) in the pre-hydrolyzed KH-560 silane solution for 5 min; after taking it out, place it in a 110℃ oven for heat treatment for 15 min to graft the silane coupling agent onto the surface of the porous ceramic transition layer to form a silane interface modification layer.

[0071] (4) Resin Composite: E-51 epoxy resin and 650 polyamide curing agent are mixed at a mass ratio of 100:50 and stirred evenly to obtain a two-component epoxy resin. The two-component epoxy resin is coated on the repair side surface of the substrate. A rubber scraper is used to scrape the resin twice along the transverse and longitudinal directions to cover the repair side surface, fill the grooves, and penetrate into the pores of the porous ceramic transition layer, while expelling the air in the pores. The coated substrate is then cured at 85°C for 30 min. After curing, a gradient cooling process is performed, i.e., the temperature is first reduced to 50°C at a rate of 2°C / min, and then kept at 50°C for 15 min. After that, it is naturally cooled to room temperature to obtain the interface-reinforced composite stainless steel substrate for the repair of curved surfaces of water-related buildings.

[0072] The interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings in this embodiment was prepared using the method described above.

[0073] This embodiment improves the conformability of the composite substrate to small-radius curved surfaces by reducing the plate thickness and the size of the grid cells, making it suitable for curved surface repair scenarios such as the outer wall of circular pipes and the corner area of ​​small-radius bridge piers.

[0074] Example 3 The method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings in this embodiment includes the following steps: (1) Substrate preparation: A 5.0mm thick 201 stainless steel plate was selected and cut into 200mm×200mm stainless steel substrates. The side of the stainless steel substrate facing the concrete structure to be repaired was defined as the repair side surface. The repair side surface was etched using a fiber laser to form a bidirectional orthogonal grid pattern, with the angle between the transverse and longitudinal etched lines being 90° and the grid unit size being 20mm×20mm. The grid pattern covered the entire repair side surface of the stainless steel substrate, with adjacent grid units sharing the corresponding etched boundary and no separate unetched intervals between adjacent grid units. The etched depth was set to 2.8mm, i.e., 56% of the plate thickness, and the etched width was 0.25mm. After etching, a multi-roller leveling machine was used for leveling. In this embodiment, the side length L of the grid unit is 20mm. According to the geometric constraint relationship of L≤0.05R, the composite stainless steel substrate prepared in this embodiment is suitable for curved surface structures with a minimum radius of curvature R of not less than 400mm on the concrete surface to be repaired.

[0075] (2) Micro-arc oxidation: The stainless steel substrate obtained in step (1) is placed as the anode in an alkaline silicate electrolyte containing sodium fluoride, so that the entire stainless steel substrate is immersed in the electrolyte; a stainless steel plate is used as the cathode. A 450V pulse voltage, a frequency of 600Hz, a duty cycle of 20%, and a processing time of 15min are used to grow a porous ceramic transition layer in situ on the surface of the stainless steel substrate. The electrolyte composition is: sodium silicate 10g / L, potassium hydroxide 2g / L, and sodium fluoride 1g / L.

[0076] Process phenomena: Fine white micro-arc discharges were observed on the repaired side surface of the stainless steel substrate, especially on the inner wall of the groove and the bottom of the groove. Since this embodiment uses immersion micro-arc oxidation treatment, other exposed surfaces of the stainless steel substrate can also form a ceramic oxide layer simultaneously; however, the functional areas used for interface enhancement and groove corrosion protection in this embodiment are mainly the repaired side surface of the stainless steel substrate, the inner wall of the groove, and the bottom of the groove.

[0077] Test results: A grayish-white porous ceramic transition layer was formed on the repaired side surface, the inner wall of the groove, and the bottom of the groove on the stainless steel substrate, with complete coverage of the groove bottom. Coating thickness measurement showed the porous ceramic transition layer to be approximately 30 μm thick; porosity measurement showed the porosity to be approximately 30%. The pores are open pores within the porous ceramic transition layer, not pores within the epoxy resin material itself.

[0078] (3) Silane modification: Prepare a 2wt% KH-560 pre-hydrolyzed silane solution. The specific steps are as follows: Mix KH-560, anhydrous ethanol and deionized water, wherein the mass ratio of anhydrous ethanol to deionized water is 90:10, and the mass of KH-560 is 2.0% of the total mass of KH-560, anhydrous ethanol and deionized water; adjust the pH of the system to 4.5 with dilute acetic acid aqueous solution, and stir and hydrolyze at 25℃ for 30 min to obtain the pre-hydrolyzed KH-560 silane solution. Immerse the repaired side surface of the stainless steel substrate obtained in step (2) in the pre-hydrolyzed KH-560 silane solution for 5 min; after taking it out, place it in a 110℃ oven for heat treatment for 15 min to graft the silane coupling agent onto the surface of the porous ceramic transition layer to form a silane interface modification layer.

[0079] (4) Resin Composite: E-51 epoxy resin and 650 polyamide curing agent were mixed at a mass ratio of 100:50 and stirred evenly to obtain a two-component epoxy resin. The two-component epoxy resin was coated on the repair side surface of the stainless steel substrate. The coating was applied twice with a rubber scraper along the transverse and longitudinal directions to cover the repair side surface, fill the grooves, and penetrate into the pores of the porous ceramic transition layer, while simultaneously expelling air from the pores. The coated stainless steel substrate was then cured at 85°C for 30 min. After curing, a gradient cooling process was performed, i.e., the temperature was first lowered to 50°C at a rate of 2°C / min, held at 50°C for 15 min, and then allowed to cool naturally to room temperature to obtain the interface-reinforced composite stainless steel substrate for the repair of curved surfaces of water-related buildings.

[0080] The interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings in this embodiment was prepared using the method described above.

[0081] This embodiment increases the thickness of the stainless steel substrate while retaining a relatively thick residual metal matrix, giving the composite stainless steel substrate high resistance to erosion and impact. It is suitable for repairing curved surfaces that are subject to strong water flow erosion, such as dam overflow surfaces, port and wharf structures, and the outer side of cross-sea bridge piers.

[0082] Example 4 The method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings in this embodiment includes the following steps: (1) Preparation of stainless steel substrate: A 1.5mm thick 201 stainless steel plate was selected and cut into 200mm×200mm stainless steel substrates. The side of the stainless steel substrate facing the concrete structure to be repaired was defined as the repair side surface. The repair side surface was etched using a fiber laser to form a bidirectional staggered grid pattern, with the angle between the transverse and longitudinal etched lines being 60°. The grid units were rhomboid in shape, with a side length of 15mm. The grid pattern covered the entire repair side surface of the stainless steel substrate, with adjacent grid units sharing the corresponding etched boundary. No unetched intervals were set between adjacent grid units. The etched depth was set to 0.60mm, which is 40% of the plate thickness, and the etched width was 0.20mm. After etching, a multi-roller leveling machine was used for leveling. In this embodiment, the side length L of the grid unit is 15mm. According to the geometric constraint relationship of L≤0.05R, the composite stainless steel substrate prepared in this embodiment is suitable for curved surface structures with a minimum radius of curvature R of not less than 300mm on the concrete surface to be repaired.

[0083] (2) Micro-arc oxidation: The stainless steel substrate obtained in step (1) is placed as the anode in an alkaline silicate electrolyte containing sodium fluoride, so that the entire stainless steel substrate is immersed in the electrolyte; a stainless steel plate is used as the cathode. A 350V pulse voltage and a current density of 5A / dm are used. 2 A porous ceramic transition layer was grown in situ on a stainless steel substrate using an electrolytic capacitor at a frequency of 600 Hz, a duty cycle of 15%, and a processing time of 10 min. The electrolyte composition was: sodium silicate 8 g / L, potassium hydroxide 1 g / L, and sodium fluoride 0.5 g / L.

[0084] Process phenomena: A relatively uniform white micro-arc discharge was observed on the repaired side surface and the etched area of ​​the stainless steel substrate. Since this embodiment uses immersion micro-arc oxidation treatment, other exposed surfaces of the stainless steel substrate can also form a ceramic oxide layer simultaneously; however, the functional areas used for interface enhancement and etched corrosion protection in this embodiment are mainly the repaired side surface of the stainless steel substrate, the inner wall of the etched groove, and the bottom of the etched groove.

[0085] Test results: A grayish-white porous ceramic transition layer was formed on the repaired side surface, the inner wall of the groove, and the bottom of the groove on the stainless steel substrate, with complete coverage of the groove bottom. Coating thickness measurement showed the porous ceramic transition layer to be approximately 10 μm thick; porosity measurement showed the porosity to be approximately 20%. The pores are open pores within the porous ceramic transition layer, not pores within the epoxy resin material itself.

[0086] (3) Silane modification: Prepare a 1wt% KH-550 pre-hydrolyzed silane solution. The specific steps are as follows: Mix KH-550, anhydrous ethanol and deionized water, wherein the mass ratio of anhydrous ethanol to deionized water is 80:20, and the mass of KH-550 is 1.0% of the total mass of KH-550, anhydrous ethanol and deionized water; adjust the pH of the system to 3.5 with dilute acetic acid aqueous solution, and stir and hydrolyze for 20 min at 20℃ to obtain a pre-hydrolyzed KH-550 silane solution. Immerse the repair side surface of the stainless steel substrate obtained in step (2) in the pre-hydrolyzed KH-550 silane solution for 3 min; after taking it out, place it in a 100℃ oven for heat treatment for 20 min to graft the silane coupling agent onto the surface of the porous ceramic transition layer to form a silane interface modification layer.

[0087] (4) Resin Composite: E-51 epoxy resin and 650 polyamide curing agent were mixed at a mass ratio of 100:40 and stirred evenly to obtain a two-component epoxy resin. The two-component epoxy resin was coated on the repair side surface of the stainless steel substrate. A rubber scraper was used to scrape the resin once in both the transverse and longitudinal directions to cover the repair side surface, fill the grooves, and penetrate into the pores of the porous ceramic transition layer. The coated stainless steel substrate was then cured at 80°C for 40 min. After curing, a gradient cooling was performed, i.e., the temperature was first reduced to 50°C at a rate of 2°C / min, and then kept at 50°C for 10 min. After that, it was naturally cooled to room temperature to obtain the interface-reinforced composite stainless steel substrate for the repair of curved surfaces of water-resistant buildings.

[0088] The interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings in this embodiment was prepared using the method described above.

[0089] Example 5 The method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings in this embodiment includes the following steps: (1) Substrate preparation: A 3.0mm thick 201 stainless steel plate was selected and cut into 200mm×200mm stainless steel substrates. The side of the stainless steel substrate facing the concrete structure to be repaired was defined as the repair side surface. The repair side surface was etched using a fiber laser to form a bidirectional orthogonal grid pattern, with the angle between the transverse and longitudinal etched lines being 90° and the grid unit size being 15mm×15mm. The grid pattern covered the entire repair side surface of the stainless steel substrate, with adjacent grid units sharing the corresponding etched boundary and no separate unetched intervals between adjacent grid units. The etched depth was set to 1.80mm, i.e., 60% of the plate thickness, and the etched width was 0.30mm. After etching, a multi-roller leveling machine was used for leveling. In this embodiment, the side length L of the grid unit is 15mm. According to the geometric constraint relationship of L≤0.05R, the composite stainless steel substrate prepared in this embodiment is suitable for curved surface structures with a minimum radius of curvature R of not less than 300mm on the concrete surface to be repaired.

[0090] (2) Micro-arc oxidation: The stainless steel substrate obtained in step (1) is placed as the anode in an alkaline silicate electrolyte containing sodium fluoride, so that the entire stainless steel substrate is immersed in the electrolyte; a stainless steel plate is used as the cathode. A 450V pulse voltage and a current density of 10A / dm³ are used. 2 A porous ceramic transition layer was grown in situ on a stainless steel substrate using an electrolytic capacitor at a frequency of 600 Hz, a duty cycle of 25%, and a processing time of 20 min. The electrolyte composition was: sodium silicate 12 g / L, potassium hydroxide 3 g / L, and sodium fluoride 1.5 g / L.

[0091] Process phenomena: Continuous and uniform white micro-arc discharges were observed on the repaired side surface and the etched area of ​​the stainless steel substrate. Since this embodiment uses immersion micro-arc oxidation treatment, other exposed surfaces of the stainless steel substrate can also form a ceramic oxide layer simultaneously; however, the functional areas used for interface enhancement and etched corrosion protection in this embodiment are mainly the repaired side surface of the stainless steel substrate, the inner wall of the etched groove, and the bottom of the etched groove.

[0092] Test results: A grayish-white porous ceramic transition layer was formed on the repaired side surface, the inner wall of the groove, and the bottom of the groove on the stainless steel substrate, with complete coverage of the groove bottom. Coating thickness measurement showed the porous ceramic transition layer to be approximately 30 μm thick; porosity measurement showed the porosity to be approximately 30%. The pores are open pores within the porous ceramic transition layer, not pores within the epoxy resin material itself.

[0093] (3) Silane modification: Prepare a 3wt% KH-570 pre-hydrolyzed silane solution. The specific steps are as follows: Mix KH-570, anhydrous ethanol and deionized water, wherein the mass ratio of anhydrous ethanol to deionized water is 95:5, and the mass of KH-570 is 3.0% of the total mass of KH-570, anhydrous ethanol and deionized water; adjust the pH of the system to 5.5 with dilute acetic acid aqueous solution, and stir and hydrolyze at 30℃ for 40 min to obtain the pre-hydrolyzed KH-570 silane solution. Immerse the repaired side surface of the stainless steel substrate obtained in step (2) in the pre-hydrolyzed KH-570 silane solution for 10 min; after taking it out, place it in a 120℃ oven for heat treatment for 10 min to graft the silane coupling agent onto the surface of the porous ceramic transition layer to form a silane interface modification layer.

[0094] (4) Resin Composite: E-51 epoxy resin and 650 polyamide curing agent were mixed at a mass ratio of 100:60 and stirred evenly to obtain a two-component epoxy resin. The two-component epoxy resin was coated on the repair side surface of the stainless steel substrate, and the epoxy resin-coated stainless steel substrate was placed in a negative pressure environment with a negative pressure of -0.08MPa. After maintaining the negative pressure for 3 minutes, the pressure was restored to normal, allowing the epoxy resin to further penetrate into the pores of the groove and porous ceramic transition layer under the action of pressure difference. Subsequently, the stainless steel substrate was cured at 90℃ for 30 minutes. After curing, a gradient cooling was performed, i.e., the temperature was first reduced to 50℃ at a rate of 3℃ / min, and then kept at 50℃ for 20 minutes. After that, it was naturally cooled to room temperature to obtain the interface-reinforced composite stainless steel substrate for the repair of curved surfaces of water-related buildings.

[0095] The interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings in this embodiment was prepared using the method described above.

[0096] Example 6 The method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings in this embodiment includes the following steps: (1) Preparation of stainless steel substrate: A 2.5mm thick 201 stainless steel plate was selected and cut into 200mm×200mm stainless steel substrates. The side of the stainless steel substrate facing the concrete structure to be repaired was defined as the repair side surface. The repair side surface was etched using a fiber laser to form a bidirectional staggered grid pattern, with the angle between the transverse and longitudinal etched lines being 75°. The grid units were rhomboid in shape, with a side length of 12mm. The grid pattern covered the entire repair side surface of the stainless steel substrate, with adjacent grid units sharing the corresponding etched boundary. No unetched intervals were set between adjacent grid units. The etched depth was set to 1.25mm, i.e., 50% of the plate thickness, and the etched width was 0.25mm. After etching, a multi-roller leveling machine was used for leveling. In this embodiment, the side length L of the grid unit is 12mm. According to the geometric constraint relationship of L≤0.05R, the composite stainless steel substrate prepared in this embodiment is suitable for curved surface structures with a minimum radius of curvature R of not less than 240mm on the concrete surface to be repaired.

[0097] (2) Micro-arc oxidation: The stainless steel substrate obtained in step (1) is placed as the anode in an alkaline silicate electrolyte containing sodium fluoride, so that the entire stainless steel substrate is immersed in the electrolyte; a stainless steel plate is used as the cathode. A 400V pulse voltage and a current density of 8A / dm are used. 2 A porous ceramic transition layer was grown in situ on a stainless steel substrate using an electrolytic capacitor at a frequency of 600 Hz, a duty cycle of 20%, and a processing time of 15 min. The electrolyte composition was: sodium silicate 10 g / L, potassium hydroxide 2 g / L, and sodium fluoride 1 g / L.

[0098] Process phenomena: Fine and uniform white micro-arc discharges were observed on the repaired side surface and the etched area of ​​the stainless steel substrate. Since this embodiment uses immersion micro-arc oxidation treatment, other exposed surfaces of the stainless steel substrate can also form a ceramic oxide layer simultaneously; however, the functional areas used for interface enhancement and etched corrosion protection in this embodiment are mainly the repaired side surface of the stainless steel substrate, the inner wall of the etched groove, and the bottom of the etched groove.

[0099] Test results: A grayish-white porous ceramic transition layer was formed on the repaired side surface, the inner wall of the groove, and the bottom of the groove on the stainless steel substrate, with complete coverage of the groove bottom. Coating thickness measurement showed the porous ceramic transition layer to be approximately 24 μm thick; porosity measurement showed the porosity to be approximately 26%. The pores are open pores within the porous ceramic transition layer, not pores within the epoxy resin material itself.

[0100] (3) Silane modification: Prepare a 2wt% compound pre-hydrolyzed silane solution. The specific steps are as follows: KH-560 and KH-550 are mixed at a mass ratio of 1:1 to obtain a compound silane coupling agent; the compound silane coupling agent, anhydrous ethanol and deionized water are mixed, wherein the mass ratio of anhydrous ethanol to deionized water is 90:10, and the mass of the compound silane coupling agent is 2.0% of the total mass of the compound silane coupling agent, anhydrous ethanol and deionized water; the pH of the system is adjusted to 4.5 using dilute acetic acid aqueous solution, and the system is stirred and hydrolyzed at 25℃ for 30 min to obtain a compound pre-hydrolyzed silane solution. The repaired side surface of the stainless steel substrate obtained in step (2) is immersed in the compound pre-hydrolyzed silane solution for 6 min; after being taken out, it is placed in a 110℃ oven for heat treatment for 15 min to graft the silane coupling agent onto the surface of the porous ceramic transition layer to form a silane interface modification layer.

[0101] (4) Resin Composite: E-51 epoxy resin and 650 polyamide curing agent were mixed at a mass ratio of 100:50 and stirred evenly to obtain a two-component epoxy resin. The two-component epoxy resin was coated on the repair side surface of the stainless steel substrate. First, a rubber scraper was used to scrape the resin back and forth twice along the transverse and longitudinal directions. Then, the stainless steel substrate was placed in a negative pressure environment with a negative pressure of -0.06MPa for 2 minutes and then restored to normal pressure to allow the epoxy resin to further fill the grooves and penetrate into the pores of the porous ceramic transition layer. Subsequently, the stainless steel substrate was cured at 85℃ for 30 minutes. After curing, a gradient cooling was performed, that is, the temperature was first reduced to 50℃ at a rate of 2℃ / min, and then kept at 50℃ for 15 minutes. After that, it was naturally cooled to room temperature to obtain the interface-reinforced composite stainless steel substrate for the repair of curved surfaces of water-related buildings.

[0102] The interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings in this embodiment was prepared using the method described above.

[0103] Comparative Example 1 The only difference between this comparative example and Example 1 is that step (3) silane modification treatment is omitted. That is, the stainless steel substrate after step (2) micro-arc oxidation treatment is no longer immersed in the pre-hydrolyzed KH-560 silane solution, and no silane interface modification layer is formed. Instead, the resin composite treatment in step (4) is carried out directly. The other raw material types, raw material ratios, indentation parameters, micro-arc oxidation parameters, epoxy resin ratios, curing conditions and gradient cooling methods are consistent with those in Example 1.

[0104] This comparative example is used to investigate the effect of omitting the silane interface modification layer on the water-resistant interfacial bonding performance of the composite stainless steel substrate when there is a lack of molecular chemical bonding between the porous ceramic transition layer and the epoxy resin layer.

[0105] Comparative Example 2 The only difference between this comparative example and Example 1 is that step (2) micro-arc oxidation treatment is omitted. That is, the stainless steel substrate after etching and roll leveling in step (1) is no longer placed in an alkaline silicate electrolyte containing sodium fluoride for micro-arc oxidation treatment, and a porous ceramic transition layer is not formed. The remaining steps are consistent with those in Example 1. Specifically, the stainless steel substrate after step (1) is directly subjected to the silane modification treatment in step (3), and then the resin composite treatment in step (4) is performed.

[0106] This comparative example is used to investigate the impact of the lack of a ceramic anti-corrosion barrier and micropore anchoring structure in the etched area on the interfacial bonding performance and corrosion resistance of the composite stainless steel substrate when a porous ceramic transition layer is not formed.

[0107] Comparative Example 3 The only difference between this comparative example and Example 1 is that the scribe depth in step (1) is set to 0.40 mm, which is 20% of the thickness of the stainless steel substrate, which is lower than the 40%-60% range specified in this invention; the other stainless steel substrate thickness, grid unit size, scribe width, micro-arc oxidation parameters, silane modification conditions, epoxy resin ratio, curing conditions and gradient cooling method are consistent with Example 1.

[0108] This comparative example is used to examine the impact of insufficient reduction in the overall stiffness of the stainless steel substrate when the scribe depth is too shallow, on the surface conformability, bending springback, and bonding stability.

[0109] Comparative Example 4 The only difference between this comparative example and Example 1 is that the scribe depth in step (1) is set to 1.40 mm, which is 70% of the thickness of the stainless steel substrate, which is higher than the 40%-60% range specified in this invention; the other stainless steel substrate thickness, grid unit size, scribe width, micro-arc oxidation parameters, silane modification conditions, epoxy resin ratio, curing conditions and gradient cooling method are consistent with Example 1.

[0110] This comparative example is used to examine the impact of excessively deep scoring on the remaining load-bearing capacity, bending stability, and damage resistance of the scoring area of ​​a stainless steel substrate when the remaining metal cross-section at the bottom of the scoring groove is too thin.

[0111] Comparative Example 5 The only difference between this comparative example and Example 1 is that the mesh unit size in step (1) is adjusted from 20mm×20mm to 40mm×40mm, that is, the side length L of the mesh unit is 40mm. According to the geometric constraint relationship of L≤0.05R, when the minimum radius of curvature R of the concrete surface to be repaired is 400mm, the side length of the mesh unit does not meet the requirement of L≤0.05R; the other scoring depth, scoring width, micro-arc oxidation parameters, silane modification conditions, epoxy resin ratio, curing conditions and gradient cooling method are consistent with those of Example 1.

[0112] This comparative example is used to examine the impact of excessively large mesh cell sizes on the fit of complex surfaces, local warping, and the risk of voids when a single mesh cell cannot fully deform with the surface.

[0113] Comparative Example 6 The only difference between this comparative example and Example 1 is that sodium fluoride is not added to the electrolyte in step (2), that is, the electrolyte composition is 10g / L sodium silicate and 2g / L potassium hydroxide, without sodium fluoride; the remaining micro-arc oxidation voltage, frequency, duty cycle, processing time, indentation parameters, silane modification conditions, epoxy resin ratio, curing conditions and gradient cooling method are consistent with Example 1.

[0114] This comparative example is used to investigate the effects of the absence of sodium fluoride in the electrolyte on the formation of the porous ceramic transition layer, the regulation of pore structure, and the effect of epoxy resin infiltration and anchoring.

[0115] Comparative Example 7 The only difference between this comparative example and Example 1 is that the pulse voltage in step (2) is adjusted from 420V to 300V, which is lower than the 350-450V range specified in this invention; the other electrolyte composition, frequency, duty cycle, processing time, scoring parameters, silane modification conditions, epoxy resin ratio, curing conditions and gradient cooling method are consistent with Example 1.

[0116] This comparative example is used to investigate the effect of insufficient micro-arc discharge intensity on the growth thickness, coverage integrity, and interface anchoring effect of porous ceramic transition layer when the micro-arc oxidation voltage is too low.

[0117] Comparative Example 8 The only difference between this comparative example and Example 1 is that the pulse voltage in step (2) is adjusted from 420V to 500V, which is higher than the 350-450V range specified in this invention; the other electrolyte composition, frequency, duty cycle, processing time, scoring parameters, silane modification conditions, epoxy resin ratio, curing conditions and gradient cooling method are consistent with Example 1.

[0118] This comparative example is used to investigate the effects of excessively high micro-arc oxidation voltage and strong partial discharge on the uniformity, film density, pore stability, and interfacial bonding performance of porous ceramic transition layers.

[0119] Comparative Example 9 The only difference between this comparative example and Example 1 is that: in step (4), no gradient cooling treatment is performed, that is, after the epoxy resin is cured at 85°C for 30 min, it is directly cooled from the curing temperature to room temperature naturally, without the gradient cooling process of "cooling down to 50°C at a rate of 2°C / min and holding at 50°C for 15 min"; the other indentation parameters, micro-arc oxidation parameters, silane modification conditions, epoxy resin ratio and curing temperature are consistent with those of Example 1.

[0120] This comparative example is used to examine the effect of residual thermal stress caused by the difference in thermal expansion coefficients between the stainless steel substrate and the epoxy resin layer on the interfacial microcracks and interfacial bonding stability when the gradient cooling process is omitted.

[0121] The performance of the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings in the above embodiments and the composite stainless steel substrate obtained in the comparative example were tested. The specific test methods are as follows.

[0122] Curved Surface Fitting and Springback Test: The processed composite stainless steel substrate was cut into 200mm × 200mm samples. Without auxiliary heating, the composite stainless steel substrate was manually bent and fitted onto the surface of a standard cylindrical mold with a radius R = 400mm. The repaired side of the composite stainless steel substrate faced the surface of the standard cylindrical mold. After removing the external force, the maximum gap between the edge of the composite stainless steel substrate and the surface of the standard cylindrical mold was measured, and this maximum gap was recorded as the springback amount. If the maximum gap was less than 1mm, it was recorded as "no obvious springback"; if the maximum gap was not less than 1mm, it was recorded as "springback present". For samples exhibiting localized cracking, localized warping, or significant detachment, the corresponding failure phenomena were also recorded.

[0123] Interface Shear Strength Test: Referring to the relevant testing methods in JC / T 547 "Ceramic Tile Adhesives", the shear strength of the bonded specimens formed between the composite stainless steel substrate and the C50 concrete block was tested. The preparation method of the bonded specimens is as follows: First, a C50 concrete block was prepared and cured under standard conditions for 28 days. Then, the surface of the C50 concrete block to be bonded was roughened by grinding to remove the laitance layer and loose particles, and the surface dust was cleaned with compressed air or anhydrous ethanol to ensure the surface to be bonded was clean and dry. Next, the composite stainless steel substrate prepared in the examples or comparative examples was cut into 50mm × 50mm specimens, with the repair side of the composite stainless steel substrate facing the surface to be bonded of the C50 concrete block. Then, a repair material layer was uniformly applied or filled between the repair side of the composite stainless steel substrate and the C50 concrete block, controlling the effective bonding area to be 50mm × 50mm and the thickness of the repair material layer to be 2mm ± 0.5mm. A composite stainless steel substrate was pressed onto the surface of a C50 concrete block, and slight pressure was applied to remove interfacial bubbles and excess repair material, forming a stable bond between the composite stainless steel substrate, the repair material layer, and the C50 concrete block. The bonded specimen was cured for 28 days at 20℃±2℃ and 50%±5% relative humidity before being used for dry shear strength testing. The repair material layer was a two-component epoxy repair material prepared by mixing E-51 epoxy resin and 650 polyamide curing agent at a mass ratio of 100:50.

[0124] Shear strength test after wet aging: The bonded specimens after the above curing were immersed in 50℃ warm water for 14 days. After removal, the surface water was wiped off, and the shear strength test was performed within 30 minutes. The shear strength after wet aging is used to characterize the water resistance stability of the composite interface between the repaired side surface of the composite stainless steel substrate, the repair material layer and the C50 concrete block. After the test, the failure modes of the specimens were recorded, including cohesive failure of concrete, cohesive failure of repair material layer, delamination of the interface between the composite stainless steel substrate and the repair material layer, delamination of the interface between the repair material layer and the concrete, corrosion at the bottom of the groove or detachment of the resin layer, etc.

[0125] Salt spray corrosion resistance test: Following GB / T 10125, a continuous spray test was conducted on the composite stainless steel substrate samples in a 5% NaCl neutral salt spray environment. Before the test, the composite stainless steel substrate was cut into 100mm × 100mm samples, and the repaired side surface was exposed to the salt spray environment. During the test, the bottom of the groove, the edge of the groove, and the edge of the resin layer were observed every 24 hours. The time when the first visible corrosion point, rust spot, interface blistering, resin layer peeling, or cracking in the groove area appeared was recorded, and this time was taken as the salt spray corrosion resistance time.

[0126] Porosity testing of porous ceramic transition layers: A stainless steel substrate sample that has undergone micro-arc oxidation treatment but has not yet been modified with silane or coated with epoxy resin was taken and cut into 50mm × 50mm pieces, with the repaired side surface used as the test area. The sample was dried in a 60℃ oven for 2 hours, cooled to room temperature, and weighed, and the result was recorded as follows. The sample was then placed in anhydrous ethanol and kept under a negative pressure of -0.08 MPa for 15 minutes to allow the anhydrous ethanol to fully penetrate the open pores of the porous ceramic transition layer. Afterward, the pressure was restored to normal and the sample was soaked for another 30 minutes. After removing the sample, the free ethanol adhering to the surface was gently wiped off with lint-free paper, and the sample was immediately weighed and recorded as follows: The open porosity P of the porous ceramic transition layer is determined according to... Calculate, where ρ is the density of anhydrous ethanol, A is the effective area of ​​the test region, and t is the average thickness of the porous ceramic transition layer.

[0127] The test results are shown in Table 1 below: Table 1 Performance test results of the examples and comparative examples

[0128] As shown in Table 1, the interface-reinforced composite stainless steel substrates for repairing curved surfaces of water-related buildings obtained in Examples 1-6 all exhibit good surface fit, interfacial bonding strength, and corrosion resistance. Notably, no significant springback or delamination was observed in any of the examples under the specified radius of curvature conditions. This indicates that controlling the notch depth to 40%-60% of the plate thickness and ensuring that the grid unit side length L and the minimum radius of curvature R of the concrete surface to be repaired satisfy L≤0.05R effectively reduces the overall bending stiffness of the substrate and improves its conformability to complex curved surfaces. Furthermore, the dry shear strength and wet-aged shear strength of Examples 1-6 remained at high levels, with strength retention rates exceeding 90%. This demonstrates that the composite interface reinforcement system, composed of notch grooves, a porous ceramic transition layer, and a silane interface modification layer, can effectively improve the water-resistant bonding stability between the epoxy resin layer and the repaired surface of the substrate in water-related or high-humidity environments.

[0129] Compared with Example 1, Comparative Example 1, after omitting the silane modification step, showed a significant decrease in shear strength and strength retention rate after wet aging. This indicates that the mechanical anchoring formed by the indentation and porous ceramic transition layer alone is insufficient to resist the long-term erosion of the interface by water molecules. The silane interface modification layer plays an important role in establishing stable chemical bonds and improving water-resistant adhesion.

[0130] Comparative Example 2, after omitting the micro-arc oxidation step, showed a significant decrease in both dry and wet shear strengths and a marked reduction in salt spray corrosion resistance time. This indicates that the porous ceramic transition layer not only provides micropore anchoring but also provides effective corrosion protection for the grooved inner wall and the bottom of the groove.

[0131] Comparative Examples 3 and 4 set the groove depth to be too shallow and too deep, respectively. The results showed that if the groove is too shallow, the substrate stiffness will be insufficiently reduced and the surface will rebound severely during bonding. If the groove is too deep, it will weaken the remaining metal cross section at the bottom of the groove, making the grooved area prone to local cracking and interface failure.

[0132] In Comparative Example 5, the excessively large mesh element size leads to local warping and voids, further illustrating that the matching relationship between the mesh element size and the radius of curvature of the surface to be repaired has a crucial impact on conformal fitting performance.

[0133] Comparative Examples 6-8 show that the addition of sodium fluoride to the electrolyte and a suitable pulse voltage range are important conditions for forming a stable porous ceramic transition layer; when sodium fluoride is lacking or the pulse voltage deviates from the reasonable range, the pore anchoring and corrosion protection effects of the ceramic transition layer will decrease.

[0134] Comparative Example 9, after omitting the gradient cooling treatment, showed a significant decrease in wet shear strength retention rate, indicating that gradient cooling helps release residual thermal stress caused by the difference in thermal expansion coefficients between the metal substrate and the epoxy resin layer, reducing the risk of interfacial microcracks.

[0135] In summary, this invention, through the synergistic effect of groove stiffness control, micro-anchoring of porous ceramic transition layer, chemical bonding of silane interface, and stress release by gradient cooling, enables the composite substrate to simultaneously possess the ability to conform to complex curved surfaces, water-resistant interface bonding performance in water-in-water environments, and corrosion protection performance in the grooved area. This effectively solves the problems of difficult curved surface bonding, easy water-induced peeling of the interface, and easy corrosion of the grooved area of ​​existing stainless steel repair substrates.

[0136] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing an interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings, characterized in that, Includes the following steps: (1) Etching the repair side surface of the stainless steel substrate to form a groove on the repair side surface; (2) The stainless steel substrate obtained by step (1) is placed in an alkaline silicate electrolyte containing sodium fluoride and a pulse voltage is applied to form a porous ceramic transition layer at least on the repair side surface and in the groove. (3) The repaired side surface of the stainless steel substrate obtained by step (2) is immersed in a pre-hydrolyzed silane solution. After immersion, it is dried to obtain a silane interface modification layer. (4) Apply epoxy resin to the repair side surface of the stainless steel substrate obtained in step (3), cure and cool to obtain the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings.

2. The method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings as described in claim 1, characterized in that, In step (1), the depth of the groove is 40%-60% of the thickness of the stainless steel substrate, and the width of the groove is 0.2-0.3 mm. The etching method is laser etching; Preferably, the notch includes a transverse notch and a longitudinal notch, and the angle between the transverse notch and the longitudinal notch is 60°-90°; The grid cells formed by the transverse and longitudinal notches are rhomboid or square, and the side length L of the grid cells and the minimum radius of curvature R of the concrete surface to be repaired satisfy the geometric constraint relationship: L≤0.05R.

3. The method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings as described in claim 1, characterized in that, The electrolyte comprises sodium silicate, sodium fluoride, and potassium hydroxide. The pulse voltage is applied for 10-20 minutes.

4. The method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings as described in claim 3, characterized in that, The concentration of sodium silicate is 8-12 g / L, the concentration of sodium fluoride is 0.5-1.5 g / L, and the concentration of potassium hydroxide is 1-3 g / L. The pulse voltage has a voltage value of 350-450V and a current density of 5-10A / dm. 2 The frequency is 600Hz, and the duty cycle is 15%-25%. The thickness of the porous ceramic transition layer is 10-30 μm; the porosity of the porous ceramic transition layer is 20%-30%. The depth h of the groove and the thickness t of the porous ceramic transition layer satisfy the following condition: h ≥ 20t.

5. The method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings as described in claim 1, characterized in that, The pre-hydrolyzed silane solution is obtained by mixing a silane coupling agent and a solvent, adjusting the pH to 3.5-5.5, and then hydrolyzing and activating for 20-40 minutes. The drying temperature is 100-120℃.

6. The method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings as described in claim 5, characterized in that, The silane coupling agent is selected from at least one of γ-glycidoxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane and γ-methacryloxypropyltrimethoxysilane; The solvent is a mixed solution of ethanol and water; the mass of the silane coupling agent is 1.0%-3.0% of the sum of the masses of the silane coupling agent and the solvent. The grafting coverage of the silane coupling agent on the surface of the porous ceramic transition layer is 0.5~2.0 g / m. 2 .

7. The method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings as described in claim 1, characterized in that, In step (4), epoxy resin is used to fill the grooves and penetrate into the pores of the porous ceramic transition layer by using a scraping process and / or a negative pressure assisted process; The curing temperature is 80-90℃; The cooling method is gradient cooling.

8. The method for preparing the interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings as described in claim 7, characterized in that, The gradient cooling process includes: first cooling to 50°C at a rate of 2-3°C / min, holding at 50°C for 10-20 minutes, and then naturally cooling to room temperature.

9. The method for preparing an interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings as described in any one of claims 1-8, characterized in that, Before step (2), there is also a step of rolling and leveling the substrate obtained by step (1); The stainless steel substrate is a 201 stainless steel plate, and the thickness of the stainless steel substrate is 1-5mm.

10. A composite stainless steel substrate with interface reinforcement for repairing curved surfaces of water-related buildings, characterized in that, The interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings is prepared using the method described in any one of claims 1-9; The interface-reinforced composite stainless steel substrate for repairing curved surfaces of water-related buildings includes a stainless steel substrate, grooves disposed on the repair side surface of the stainless steel substrate, a porous ceramic transition layer formed on at least the repair side surface of the stainless steel substrate and the inner wall and bottom of the grooves, a silane interface modification layer grafted onto the surface of the porous ceramic transition layer, and an epoxy resin layer disposed on the repair side surface of the stainless steel substrate and filling the pores of the grooves and the porous ceramic transition layer.

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