High-performance weathering steel, preparation method thereof and application of high-performance weathering steel in bridge

Abstract

The invention relates to the technical field of weathering resistant steel, in particular to high-performance weathering resistant steel and a preparation method and application thereof in bridges, the weathering resistant steel comprises a weathering resistant steel base material, and the weathering resistant steel is characterized in that a protective coating is arranged on the surface of the weathering resistant steel base material; the protective coating comprises the following raw materials of, by mass, 18%-30% of Cr, 1%-4% of Mo, 2%-5% of Si, 1%-6% of Al, 3%-8% of Ti, 0.5%-1.5% of B, 2%-5% of nanometer SiO2 and the balance Fe. According to the method, the three-step core process of base material pretreatment, composite coating thermal spraying, controllable nitriding and oxidation treatment is adopted, and coating component optimization is combined, so that the high-salt weather resistance of the weather-resistant steel is achieved.

Description

Technical Field

[0001] This invention relates to the field of weathering steel technology, specifically to a high-performance weathering steel, its preparation method, and its application in bridges. Background Technology

[0002] Weathering steel, also known as atmospheric corrosion-resistant steel, is made by adding a certain proportion of alloying elements (such as Cu, P, Cr, Ni, etc.) to ordinary steel, causing it to spontaneously form a dense and stable rust layer on its surface when exposed to the atmosphere. This rust layer effectively prevents the penetration of moisture and oxygen, thereby significantly reducing the corrosion rate of the steel and extending its service life. Due to its "rust-preventing" property and the elimination of painting and maintenance costs, weathering steel is widely used in large steel structures such as bridges, buildings, railway vehicles, and towers that are exposed to the atmosphere for extended periods. However, weathering steel takes several years to form an effective protective rust layer under natural conditions, and is prone to "yellow water" pollution in the initial stage, with an early corrosion rate as high as 0.2 mm / year. In a 3.5% NaCl salt spray environment, the rust layer of traditional weathering steel is prone to "rust peeling," with the corrosion rate increasing to 3-5 times that of the natural environment, which cannot meet the requirements of marine engineering.

[0003] Existing technologies often employ chemical rust-inducing methods and protective coatings to address the aforementioned shortcomings. However, chemical rust-inducing methods (such as dilute hydrochloric acid pretreatment) easily lead to intergranular corrosion of the substrate, and the rust layer has insufficient density; although thermal spraying zinc-aluminum coatings can provide short-term protection, they are prone to "excessive consumption of sacrificial anodes" in high-salt environments above 60°C, resulting in a coating lifespan of only 2-3 years. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the purpose of this invention is to provide a high-performance weathering steel, its preparation method and its application in bridges, so as to solve the problems mentioned in the background art.

[0005] The present invention solves the technical problem by adopting the following technical solution: This invention provides a high-performance weathering steel, which includes a weathering steel substrate and a protective coating on the surface of the weathering steel substrate; The protective coating contains the following raw materials by weight percentage: Cr 18-30%, Mo 1-4%, Si 2-5%, Al 1-6%, Ti 3-8%, B 0.5-1.5%, Nano-SiO 2-5%, balance Fe.

[0006] Preferably, the Ti is further subjected to conditioning treatment, specifically the following treatment method: S01: Stir Ti powder in a sufficient amount of potassium permanganate solution, then wash with water, filter and dry. Heat the dried Ti powder at 210-220℃ for 1 hour, then cool it down to 55-60℃ at a rate of 3-5℃ / min and keep it at that temperature. S02: Sort the Ti powder and conditioning solution of S01 by ultrasonic treatment at a weight ratio of 5:(9-11). After treatment, filter and dry.

[0007] Preferably, the mass fraction of the potassium permanganate solution is 10-15%; the ultrasonic power of the ultrasonic conditioning treatment is 350-400W, and the ultrasonic treatment lasts for 20-30 minutes.

[0008] Preferably, the preparation method of the conditioning solution is as follows: S02a: Mix silane coupling agent KH550, 85-90% ethanol solution and β-cyclodextrin in a mass ratio of (2-5):7:(1-3) to obtain silane solution; SO2b: 2-4 parts graphene, 1-3 parts sodium dodecylbenzenesulfonate solution and 5-8 parts silane solution are mixed evenly, and then 3-5 parts silica are added and mixed evenly to obtain graphene-based solution. S02c: 3-5 parts silicon carbide whiskers, 2-3 parts lanthanum oxide and 1-2 parts hydroxyapatite are blended and sintered for 1 hour. After sintering, a sintered body is obtained. The sintered body and graphene-based liquid are stirred thoroughly at a weight ratio of 3:(5-8) to obtain a conditioning liquid.

[0009] S01 pretreatment (potassium permanganate oxidation + gradient heat treatment): optimizes the surface state of Ti powder, laying the foundation for "strong bonding and high corrosion resistance". The conditioning solution is a composite functional system composed of "silane coupling agent + graphene + silicon carbide whiskers + rare earth / hydroxyapatite". The components do not act independently, but form "functional complementarity" through synergy. S02a: silane liquid (KH550 + ethanol + β-cyclodextrin) - "bridging agent + dispersing stabilizer". Silane coupling agent KH550: solves the "bonding force problem between Ti powder and coating matrix". KH550 molecules contain "amino (-NH2)" and "siloxane (-Si(OR)3)" at both ends: the amino can undergo a condensation reaction with the hydroxyl (-OH) of TiO2 on the surface of Ti powder after S01 treatment (forming -NH-Si-O- bonds), and the siloxane can combine with metal elements such as Fe and Cr in the coating during subsequent plasma spraying, which is equivalent to the bonding force between Ti powder and coating matrix. A "chemical bridge" is built between the powder and the coating, upgrading their bonding force from "mechanical interlocking" to "chemical bonding," thus preventing Ti powder from falling off during coating use due to vibration and temperature differences.

[0010] Graphene can enhance the coating's resistance to penetration and wear. Graphene is a single-atom-layer two-dimensional material with extremely high chemical stability and mechanical strength, but it is prone to agglomeration. 5-10% sodium dodecylbenzenesulfonate (surfactant) can break up graphene agglomeration by adsorbing the hydrophobic end of graphene and dispersing the hydrophilic end in the solution, making it uniformly dispersed in the base liquid. The graphene subsequently attached to the Ti powder surface can form a continuous corrosion-resistant barrier in the coating, blocking the penetration paths of Cl⁻ and oxygen. At the same time, the high hardness of graphene (~1000HV) can improve the wear resistance of the coating and reduce the damage to the coating caused by wind, sand and vehicle friction during bridge service. Silica fills the pores of the coating and improves its density. The fine silica particles (micron-level) can synergistically fill the tiny pores of the subsequent plasma-sprayed coating with graphene. At the same time, silica has good compatibility with TiO2 on the Ti powder surface, which can further enhance the interfacial bonding between Ti powder and the coating. Silicon carbide whiskers (one-dimensional reinforcements) enhance the coating's resistance to cracking and impact. Silicon carbide whiskers are fibrous single crystals (1-5 μm in diameter, 50-100 μm in length). Sintering at 300-350℃ allows them to bond tightly with lanthanum oxide and hydroxyapatite. The whiskers act as a "skeleton support" in the coating: when the coating is subjected to stress from temperature differences or vibrations, the whiskers can absorb energy through the "fiber pull-out effect," preventing the coating from cracking. Simultaneously, silicon carbide's excellent corrosion resistance further enhances the coating's resistance to salt spray. Hydroxyapatite possesses excellent biocompatibility and chemical stability, and in humid environments, it can slowly release Ca²⁺ and PO₄³⁻. These ions can form "calcium phosphate precipitates" at minor damage points in the coating, blocking the damage and achieving "self-repair." This prevents corrosive media from penetrating the substrate through the damage. Through the harmonious blending of raw materials, they work together to optimize the system's performance and stability.

[0011] Preferably, the sintering temperature of the blend is 300-350℃; the mass fraction of the sodium dodecylbenzenesulfonate solution is 5-10%.

[0012] Preferably, the nano-SiO The modification process also employs a stirring treatment with a modified liquid. The specific modification method is as follows: S11: Mix 2-5 parts of 4% yttrium nitrate solution, 1-3 parts of boron nitride and 3-5 parts of nanocellulose evenly to obtain yttrium solution; stir the yttrium solution, additives and sodium alginate solution in a weight ratio of (3-5):2:(4-6) thoroughly to obtain modified solution; S12: SiO Preheat at 60-65℃ for 1 hour, then preheat the SiO2. The modified liquid is stirred and modified at a weight ratio of 5:(8-11). After stirring, it is filtered and dried. The additive is prepared by mixing nano-chromium oxide, Nb powder and zirconium powder in a weight ratio of (2-4):(1-3):2.

[0013] Yttrium-based liquid (yttrium nitrate + boron nitride + nanocellulose): laying the foundation for "corrosion resistance + dispersion + toughness"; 4% yttrium nitrate solution (Y³⁺ precursor): forms a "highly stable Y₂O₃ passivation film" to block the corrosive medium. Y³⁺ in yttrium nitrate is a key corrosion-resistant element. At the same time, Y₂O₃ can form a "Y₂O₃-Cr₂O₃ solid solution" with Cr₂O₃ in the coating, further enhancing the passivation film's resistance to high-temperature oxidation (preventing the coating from oxidizing and failing during the high temperatures of summer on bridges). Boron nitride introduces a "layered buffer structure" to improve the coating's resistance to cracking and wear. Boron nitride is hexagonal, while nanocellulose solves the "dispersion problem of BN and Y³⁺" and enhances the stability of the modified liquid. Nanocellulose is a natural polymer with a surface rich in hydroxyl groups (-OH), and has the functions of both "dispersant" and "binder". Nano Cr2O3 works synergistically with the Cr element in the coating substrate to form a "double passivation barrier". Nano Cr2O3 itself is an excellent passivating agent. When matched with nano SiO2, it can be uniformly attached to the SiO2 surface. In the subsequent coating, Cr2O3 will work synergistically with the Cr element in the substrate / coating to form a double passivation film on the surface of "inner layer Cr2O3 (substrate source) + outer layer Cr2O3 (additive source)", which further reduces the permeability of corrosive media. Zirconium powder can improve the "high temperature stability" of coatings. When zirconium powder adheres to the surface of SiO2, it can enhance the coating's resistance to softening at high temperatures, prevent the coating from losing hardness due to high temperatures, and ensure long-term wear resistance. Through the blending and optimization of raw materials, the performance of the system can be further enhanced.

[0014] Preferably, the sodium alginate solution has a mass fraction of 8-12%; the stirring speed for the stirring modification treatment is 450-550 r / min, and the stirring time is 1 h.

[0015] This invention also provides a method for preparing high-performance weathering steel, comprising the following steps: S1. Substrate pretreatment: The weathering steel substrate is sandblasted to achieve a cleanliness level of Sa2.5 and a surface roughness Ra of 5.0-8.0μm, and then cleaned and activated. S2. Spray coating: Using atmospheric plasma spraying process, the alloy powder of the composition described in claim 1 is sprayed onto the surface of the treated substrate to form a coating with a thickness of 150-400μm. S3, Nitriding-Oxidation Treatment: The sprayed coating is subjected to low-temperature nitriding treatment and subsequent oxidation treatment in sequence.

[0016] Preferably, the low-temperature nitriding treatment is performed by holding the mixture at 500-580°C for 2-4 hours in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 1:3. The subsequent oxidation treatment is as follows: in a humid air atmosphere with a relative humidity of 60-80%, heat at 600-700℃ for 1-3 hours; In step S1, the sandblasting roughening uses 0.8-1.2mm alloy steel grit and the compressed air pressure is 0.6-0.7MPa; the cleaning and activation involves blowing with 0.1MPa compressed air and then ultrasonically cleaning with 300W anhydrous ethanol for 5-10 minutes. In step S2, the parameters for atmospheric plasma spraying are as follows: the plasma gas is a mixture of Ar and hydrogen, the Ar gas flow rate is 40-60 L / min, and the hydrogen gas flow rate is 5-8 L / min; the spraying current is 400-500 A, and the voltage is 60-80 V; the spraying distance is 150-200 mm; the powder feeding rate is 25-40 g / min; and compressed air is used for side-blowing cooling during the spraying process to control the coating surface temperature to ≤300℃. After step S3, step S4, sealing treatment, is also included: using vacuum impregnation, the coating is impregnated with siloxane resin containing 8-12wt% molybdate corrosion inhibitor, the vacuum degree is -0.08 to -0.09MPa, the impregnation time is 15-20 minutes, and then cured at 120-150℃ for 2-3 hours.

[0017] This invention also provides an application of high-performance weathering steel in bridges.

[0018] Sealing treatment for the nitrided and oxidized coating: Sealing agent: siloxane resin containing 8-12wt% molybdate corrosion inhibitor; Process: Vacuum impregnation method (vacuum degree -0.08 to -0.09MPa, impregnation time 15-20min), followed by curing at 120-150℃ for 2-3h; After sealing, the contact angle of the coating surface is ≥110°, it has hydrophobic self-cleaning function, and the corrosion inhibitor can repair microcracks through capillary action.

[0019] After undergoing a 5% NaCl salt spray cycle test (35℃, 1000h), the coating showed no red rust formation, and the corrosion spread rate at scratches was <0.1mm / year, which is 5-8 times higher than that of traditional thermal spray zinc-aluminum coatings (corrosion rate 0.5-0.8mm / year). The coating exhibits excellent performance: the coating porosity is ≤1%, the bonding strength is ≥55MPa (GB / T8642-2022 standard test), and the hardness is ≥450HV, which can resist the erosion and wear of salt particles. The process is highly efficient: after preparation, there is no need to wait for the natural rust layer to form, and it can be directly used in high-salt environments, shortening the protection start-up cycle from "several years" to "within 72 hours". It is environmentally friendly: there is no chemical rust accelerator pollution, and the oxidation burn-off rate during the thermal spraying process is <3%, which is more than 60% lower than that of traditional processes.

[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention employs a three-step core process: substrate pretreatment, thermal spraying composite coating, controlled nitriding, and oxidation treatment. Combined with coating composition optimization, this achieves high salt resistance of weathering steel. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to specific examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This embodiment provides a high-performance weathering steel, which includes a weathering steel substrate and a protective coating on the surface of the weathering steel substrate. The protective coating contains the following raw materials by weight percentage: Cr 18-30%, Mo 1-4%, Si 2-5%, Al 1-6%, Ti 3-8%, B 0.5-1.5%, Nano-SiO 2-5%, balance Fe.

[0023] In this embodiment, Ti is also subjected to modulation processing. The specific processing method is as follows: S01: Stir Ti powder in a sufficient amount of potassium permanganate solution, then wash with water, filter and dry. Heat the dried Ti powder at 210-220℃ for 1 hour, then cool it down to 55-60℃ at a rate of 3-5℃ / min and keep it at that temperature. S02: Sort the Ti powder and conditioning solution of S01 by ultrasonic treatment at a weight ratio of 5:(9-11). After treatment, filter and dry.

[0024] In this embodiment, the mass fraction of the potassium permanganate solution is 10-15%; the ultrasonic power of the ultrasonic conditioning treatment is 350-400W, and the ultrasonic treatment lasts for 20-30 minutes.

[0025] The preparation method of the conditioning solution in this embodiment is as follows: S02a: Mix silane coupling agent KH550, 85-90% ethanol solution and β-cyclodextrin in a mass ratio of (2-5):7:(1-3) to obtain silane solution; SO2b: 2-4 parts graphene, 1-3 parts sodium dodecylbenzenesulfonate solution and 5-8 parts silane solution are mixed evenly, and then 3-5 parts silica are added and mixed evenly to obtain graphene-based solution. S02c: 3-5 parts silicon carbide whiskers, 2-3 parts lanthanum oxide and 1-2 parts hydroxyapatite are blended and sintered for 1 hour. After sintering, a sintered body is obtained. The sintered body and graphene-based liquid are stirred thoroughly at a weight ratio of 3:(5-8) to obtain a conditioning liquid.

[0026] The sintering temperature for the blending in this embodiment is 300-350℃; the mass fraction of the sodium dodecylbenzenesulfonate solution is 5-10%.

[0027] Nano SiO in this embodiment The modification process also employs a stirring treatment with a modified liquid. The specific modification method is as follows: S11: Mix 2-5 parts of 4% yttrium nitrate solution, 1-3 parts of boron nitride and 3-5 parts of nanocellulose evenly to obtain yttrium solution; stir the yttrium solution, additives and sodium alginate solution in a weight ratio of (3-5):2:(4-6) thoroughly to obtain modified solution; S12: SiO Preheat at 60-65℃ for 1 hour, then preheat the SiO2. The modified liquid is stirred and modified at a weight ratio of 5:(8-11). After stirring, it is filtered and dried. The additive is prepared by mixing nano-chromium oxide, Nb powder and zirconium powder in a weight ratio of (2-4):(1-3):2.

[0028] In this embodiment, the sodium alginate solution has a mass fraction of 8-12%; the stirring speed for the stirring modification treatment is 450-550 r / min, and the stirring time is 1 h.

[0029] This embodiment of a method for preparing high-performance weathering steel includes the following steps: S1. Substrate pretreatment: The weathering steel substrate is sandblasted to achieve a cleanliness level of Sa2.5 and a surface roughness Ra of 5.0-8.0μm, and then cleaned and activated. S2. Spray coating: Using atmospheric plasma spraying process, the alloy powder of the composition described in claim 1 is sprayed onto the surface of the treated substrate to form a coating with a thickness of 150-400μm. S3, Nitriding-Oxidation Treatment: The sprayed coating is subjected to low-temperature nitriding treatment and subsequent oxidation treatment in sequence.

[0030] The low-temperature nitriding treatment in this embodiment is as follows: in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 1:3, the temperature is maintained at 500-580°C for 2-4 hours. The subsequent oxidation treatment is as follows: in a humid air atmosphere with a relative humidity of 60-80%, heat at 600-700℃ for 1-3 hours; In step S1, the sandblasting roughening uses 0.8-1.2mm alloy steel grit and the compressed air pressure is 0.6-0.7MPa; the cleaning and activation involves blowing with 0.1MPa compressed air and then ultrasonically cleaning with 300W anhydrous ethanol for 5-10 minutes. In step S2, the parameters for atmospheric plasma spraying are as follows: the plasma gas is a mixture of Ar and hydrogen, the Ar gas flow rate is 40-60 L / min, and the hydrogen gas flow rate is 5-8 L / min; the spraying current is 400-500 A, and the voltage is 60-80 V; the spraying distance is 150-200 mm; the powder feeding rate is 25-40 g / min; and compressed air is used for side-blowing cooling during the spraying process to control the coating surface temperature to ≤300℃. After step S3, step S4, sealing treatment, is also included: using vacuum impregnation, the coating is impregnated with siloxane resin containing 8-12wt% molybdate corrosion inhibitor, the vacuum degree is -0.08 to -0.09MPa, the impregnation time is 15-20 minutes, and then cured at 120-150℃ for 2-3 hours.

[0031] This embodiment describes the application of high-performance weathering steel in bridges.

[0032] Example 1 The substrate of Q355NH weathering steel plate was sandblasted using 1mm alloy steel grit under a compressed air pressure of 0.7MPa. Immediately after sandblasting, the surface dust was blown away with 0.1MPa compressed air, followed by ultrasonic cleaning with anhydrous ethanol at a power of 300W for 8 minutes. After drying, the substrate was then subjected to thermal spraying within 1 hour.

[0033] The composite powder consists of the following components by mass percentage: Cr: 25%, Mo: 2.5%, Si: 3.5%, Al: 3.0%, Ti: 5.0%, B: 1.0%, nano-SiO2: 3.0%, Fe, and unavoidable impurities. The powder is prepared by gas atomization at a pressure of 7 MPa using Ar gas as the atomizing medium. A particle size of 100 μm is used to ensure compositional uniformity and that the nano-SiO2 particles are dispersed throughout the powder.

[0034] APS spray coating preparation: Ar: 50 L / min, H2: 6 L / min; current: 450 A; voltage: 70 V; distance: 180 mm; powder feed rate: 35 g / min. Compressed air side-blowing cooling was used during spraying to control the coating surface temperature ≤300℃.

[0035] A mixed gas with a volume ratio of N2:H2=1:3 and a flow rate of 10L / min was introduced, and the temperature was raised to 550℃ and held for 3 hours. The atmosphere was then switched to humid air with a relative humidity of 70% and an O2 volume fraction of 25%, and the temperature was raised to 650℃ and held for 2 hours. After the furnace cooled to 300℃, Ar gas was switched to protective cooling at a cooling rate of 10℃ / min, and the furnace was removed after reaching room temperature.

[0036] The nitrided-oxidized coating was then sealed. Sealing agent: siloxane resin containing 10wt% molybdate corrosion inhibitor; Process: vacuum impregnation method (vacuum degree -0.08MPa, impregnation time 20min), followed by curing at 130℃ for 2.5h.

[0037] A neutral salt spray test (NSS, ASTM B117) was then conducted. Evaluation metrics included: Time to red rust appearance (hours): Recording the time when red rust caused by matrix corrosion first appeared on the sample surface. Scratch corrosion propagation width (mm) after 1000 hours of salt spray testing. Overall morphology description after 1000 hours of salt spray testing.

[0038] Example 2 The substrate of Q355NH weathering steel plate was sandblasted using 1mm alloy steel grit under a compressed air pressure of 0.7MPa. Immediately after sandblasting, the surface dust was blown away with 0.1MPa compressed air, followed by ultrasonic cleaning with anhydrous ethanol at a power of 300W for 8 minutes. After drying, the substrate was then subjected to thermal spraying within 1 hour.

[0039] The composite powder consists of the following components by mass percentage: Cr: 28%, Mo: 3.0%, Si: 4.0%, Al: 4.0%, Ti: 6.0%, B: 1.2%, nano-SiO2: 4.0%, Fe, and unavoidable impurities. The powder was prepared by gas atomization at a pressure of 7 MPa using Ar gas as the atomizing medium. A particle size of 100 μm was used to ensure uniform composition and that the nano-SiO2 particles were dispersed throughout the powder.

[0040] APS spray coating preparation: Ar: 55 L / min, H2: 7 L / min; Current: 480 A; Voltage: 75 V; Distance: 170 mm; Powder feed rate: 30 g / min. Compressed air side-blowing cooling was used during spraying to control the coating surface temperature ≤300℃.

[0041] A mixed gas with a volume ratio of N2:H2=1:3 and a flow rate of 10L / min was introduced, and the temperature was raised to 560℃ and held for 3.5h. The atmosphere was then switched to humid air with a relative humidity of 75% and an O2 volume fraction of 25%, and the temperature was raised to 670℃ and held for 1.5h. After cooling to 300℃ with the furnace, Ar gas was switched to protective cooling at a cooling rate of 10℃ / min, and the furnace was removed after reaching room temperature.

[0042] The nitrided-oxidized coating was then sealed. Sealing agent: siloxane resin containing 10wt% molybdate corrosion inhibitor; Process: vacuum impregnation method (vacuum degree -0.08MPa, impregnation time 20min), followed by curing at 130℃ for 2.5h.

[0043] A neutral salt spray test (NSS, ASTM B117) was then conducted. Evaluation metrics included: Time to red rust appearance (hours): Recording the time when red rust caused by matrix corrosion first appeared on the sample surface. Scratch corrosion propagation width (mm) after 1000 hours of salt spray testing. Overall morphology description after 1000 hours of salt spray testing.

[0044] Example 3 The substrate of Q355NH weathering steel plate was sandblasted using 1mm alloy steel grit under a compressed air pressure of 0.7MPa. Immediately after sandblasting, the surface dust was blown away with 0.1MPa compressed air, followed by ultrasonic cleaning with anhydrous ethanol at a power of 300W for 8 minutes. After drying, the substrate was then subjected to thermal spraying within 1 hour.

[0045] The composite powder consists of the following components by mass percentage: Cr: 22%, Mo: 2.0%, Si: 3.0%, Al: 2.0%, Ti: 4.0%, B: 0.8%, nano-SiO2: 2.5%, Fe, and unavoidable impurities. The powder is prepared by gas atomization at a pressure of 7 MPa using Ar gas as the atomizing medium. A particle size of 100 μm is used to ensure compositional uniformity and that the nano-SiO2 particles are dispersed throughout the powder.

[0046] APS spray coating preparation: Ar: 45 L / min, H2: 5 L / min; Current: 420 A; Voltage: 65 V; Distance: 190 mm; Powder feed rate: 38 g / min. Compressed air side-blowing cooling was used during spraying to control the coating surface temperature ≤300℃.

[0047] A mixed gas with a volume ratio of N2:H2=1:3 and a flow rate of 10L / min was introduced, and the temperature was raised to 530℃ and held for 4 hours. The atmosphere was then switched to humid air with a relative humidity of 65% and an O2 volume fraction of 25%, and the temperature was raised to 620℃ and held for 3 hours. After the furnace cooled to 300℃, Ar gas was switched to protective cooling at a cooling rate of 10℃ / min, and the furnace was removed after reaching room temperature.

[0048] The nitrided-oxidized coating was then sealed. Sealing agent: siloxane resin containing 10wt% molybdate corrosion inhibitor; Process: vacuum impregnation method (vacuum degree -0.08MPa, impregnation time 20min), followed by curing at 130℃ for 2.5h.

[0049] A neutral salt spray test (NSS, ASTM B117) was then conducted. Evaluation metrics included: Time to red rust appearance (hours): Recording the time when red rust caused by matrix corrosion first appeared on the sample surface. Scratch corrosion propagation width (mm) after 1000 hours of salt spray testing. Overall morphology description after 1000 hours of salt spray testing.

[0050] Comparative Example 1 The substrate of Q355NH weathering steel plate was sandblasted using 1mm alloy steel grit under a compressed air pressure of 0.7MPa. Immediately after sandblasting, the surface dust was blown away with 0.1MPa compressed air, followed by ultrasonic cleaning with anhydrous ethanol at a power of 300W for 8 minutes. After drying, the substrate was then subjected to thermal spraying within 1 hour.

[0051] The composite powder consists of the following components by mass percentage: Cr: 25%, Mo: 2.5%, Si: 3.5%, Al: 3.0%, Fe, and unavoidable impurities. The powder is prepared by gas atomization at a pressure of 7 MPa using Ar gas as the atomizing medium. A particle size of 100 μm is used to ensure compositional uniformity and that nano-SiO2 particles are dispersed throughout the powder.

[0052] APS spray coating preparation: Ar: 55 L / min, H2: 7 L / min; Current: 480 A; Voltage: 75 V; Distance: 170 mm; Powder feed rate: 30 g / min. Compressed air side-blowing cooling was used during spraying to control the coating surface temperature ≤300℃.

[0053] A mixed gas with a volume ratio of N2:H2=1:3 and a flow rate of 10L / min was introduced, and the temperature was raised to 560℃ and held for 3.5h. The atmosphere was then switched to humid air with a relative humidity of 75% and an O2 volume fraction of 25%, and the temperature was raised to 670℃ and held for 1.5h. After cooling to 300℃ with the furnace, Ar gas was switched to protective cooling at a cooling rate of 10℃ / min, and the furnace was removed after reaching room temperature.

[0054] The nitrided-oxidized coating was sealed. Sealing agent: siloxane resin containing 10wt% molybdate corrosion inhibitor; process: vacuum impregnation method (vacuum degree -0.08MPa, impregnation time 20min), followed by curing at 130℃ for 2.5h.

[0055] A neutral salt spray test (NSS, ASTM B117) was then conducted. Evaluation metrics included: Time to red rust appearance (hours): Recording the time when red rust caused by matrix corrosion first appeared on the sample surface. Scratch corrosion propagation width (mm) after 1000 hours of salt spray testing. Overall morphology description after 1000 hours of salt spray testing.

[0056] Comparative Example 2 The substrate of Q355NH weathering steel plate was sandblasted using 1mm alloy steel grit under a compressed air pressure of 0.7MPa. Immediately after sandblasting, the surface dust was blown away with 0.1MPa compressed air, followed by ultrasonic cleaning with anhydrous ethanol at a power of 300W for 8 minutes. After drying, the substrate was then subjected to thermal spraying within 1 hour.

[0057] The composite powder consists of the following components by mass percentage: Cr: 25%, Mo: 2.5%, Si: 3.5%, Al: 3.0%, Ti: 1.0%, B: 1.0%, nano-SiO2: 3.0%, Fe, and unavoidable impurities. The powder is prepared by gas atomization at a pressure of 7 MPa using Ar gas as the atomizing medium. A particle size of 100 μm is used to ensure compositional uniformity and that the nano-SiO2 particles are dispersed throughout the powder.

[0058] APS spray coating preparation: Ar: 55 L / min, H2: 7 L / min; Current: 480 A; Voltage: 75 V; Distance: 170 mm; Powder feed rate: 30 g / min. Compressed air side-blowing cooling was used during spraying to control the coating surface temperature ≤300℃.

[0059] A mixed gas with a volume ratio of N2:H2=1:3 and a flow rate of 10L / min was introduced, and the temperature was raised to 560℃ and held for 3.5h. The atmosphere was then switched to humid air with a relative humidity of 75% and an O2 volume fraction of 25%, and the temperature was raised to 670℃ and held for 1.5h. After cooling to 300℃ with the furnace, Ar gas was switched to protective cooling at a cooling rate of 10℃ / min, and the furnace was removed after reaching room temperature.

[0060] The nitrided-oxidized coating was then sealed. Sealing agent: siloxane resin containing 10wt% molybdate corrosion inhibitor; Process: vacuum impregnation method (vacuum degree -0.08MPa, impregnation time 20min), followed by curing at 130℃ for 2.5h.

[0061] A neutral salt spray test (NSS, ASTM B117) was then conducted. Evaluation metrics included: Time to red rust appearance (hours): Recording the time when red rust caused by matrix corrosion first appeared on the sample surface. Scratch corrosion propagation width (mm) after 1000 hours of salt spray testing. Overall morphology description after 1000 hours of salt spray testing.

[0062] Comparative Example 3 The substrate of Q355NH weathering steel plate was sandblasted using 1mm alloy steel grit under a compressed air pressure of 0.7MPa. Immediately after sandblasting, the surface dust was blown away with 0.1MPa compressed air, followed by ultrasonic cleaning with anhydrous ethanol at a power of 300W for 8 minutes. After drying, the substrate was then subjected to thermal spraying within 1 hour.

[0063] The composite powder consists of the following components by mass percentage: Cr: 28%, Mo: 3.0%, Si: 4.0%, Al: 4.0%, Ti: 6.0%, B: 1.2%, nano-SiO2: 4.0%, Fe, and unavoidable impurities. The powder was prepared by gas atomization at a pressure of 7 MPa using Ar gas as the atomizing medium. A particle size of 100 μm was used to ensure compositional uniformity and that the nano-SiO2 particles were dispersed throughout the powder.

[0064] APS spray coating preparation: Ar: 55 L / min, H2: 7 L / min; Current: 480 A; Voltage: 75 V; Distance: 170 mm; Powder feed rate: 30 g / min. Compressed air side-blowing cooling was used during spraying to control the coating surface temperature ≤300℃.

[0065] Humidified air was introduced, with a relative humidity of 75% and an O2 volume fraction of 25%, and the temperature was raised to 670℃ and held for 1.5 hours. After cooling to 300℃ in the furnace, Ar gas was switched to protective cooling at a rate of 10℃ / min. The furnace was then removed after reaching room temperature.

[0066] The oxidized coating was then sealed. Sealing agent: siloxane resin containing 10wt% molybdate corrosion inhibitor; Process: vacuum impregnation method (vacuum degree -0.08MPa, impregnation time 20min), followed by curing at 130℃ for 2.5h.

[0067] A neutral salt spray test (NSS, ASTM B117) was then conducted. Evaluation metrics included: Time to red rust appearance (hours): Recording the time when red rust caused by matrix corrosion first appeared on the sample surface. Scratch corrosion propagation width (mm) after 1000 hours of salt spray testing. Overall morphology description after 1000 hours of salt spray testing.

[0068] Comparative Example 4 The substrate of Q355NH weathering steel plate was sandblasted using 1mm alloy steel grit under a compressed air pressure of 0.7MPa. Immediately after sandblasting, the surface dust was blown away with 0.1MPa compressed air, followed by ultrasonic cleaning with anhydrous ethanol at a power of 300W for 8 minutes. After drying, the substrate was then subjected to thermal spraying within 1 hour.

[0069] The composite powder consists of the following components by mass percentage: Cr: 28%, Mo: 3.0%, Si: 4.0%, Al: 4.0%, Ti: 6.0%, B: 1.2%, nano-SiO2: 4.0%, Fe, and unavoidable impurities. The powder was prepared by gas atomization at a pressure of 7 MPa using Ar gas as the atomizing medium. A particle size of 100 μm was used to ensure uniform composition and that the nano-SiO2 particles were dispersed throughout the powder.

[0070] APS spray coating preparation: Ar: 55 L / min, H2: 7 L / min; Current: 480 A; Voltage: 75 V; Distance: 170 mm; Powder feed rate: 30 g / min. Compressed air side-blowing cooling was used during spraying to control the coating surface temperature ≤300℃.

[0071] Sealing treatment. Sealing agent: siloxane resin containing 10wt% molybdate corrosion inhibitor; Process: vacuum impregnation method (vacuum degree -0.08MPa, impregnation time 20min), followed by curing at 130℃ for 2.5h.

[0072] A neutral salt spray test (NSS, ASTM B117) was then conducted. Evaluation metrics included: Time to red rust appearance (hours): Recording the time when red rust caused by matrix corrosion first appeared on the sample surface. Scratch corrosion propagation width (mm) after 1000 hours of salt spray testing. Overall morphology description after 1000 hours of salt spray testing.

[0073] Examples 1-4 and Comparative Examples 1-7 underwent routine performance tests for thermal insulation and impact resistance, while also testing weather resistance and thermal cycling stability (UV intensity 500 W / m²). The sample was irradiated for 24 hours, then placed at 65℃ for 12 hours, and then placed at -5℃ for 12 hours. This constituted one cycle, which was repeated 10 times. The test results are as follows:

[0074] As shown in Examples 1-3 and Comparative Examples 1-4, the product of Example 2 of the present invention has excellent corrosion resistance.

[0075] Based on Example 2, the present invention has been further optimized. The specific optimization scheme is as follows: Optimization Example 1: Ti also undergoes conditioning processing, specifically the following methods: S01: Stir Ti powder in a sufficient amount of potassium permanganate solution, then wash with water, filter and dry. Heat the dried Ti powder at 210℃ for 1 hour, then cool it down to 55℃ at a rate of 3℃ / min and keep it at that temperature. S02: Ultrasonically treat the Ti powder and conditioning solution of S01 at a weight ratio of 5:9. After the treatment is completed, filter and dry.

[0076] In this embodiment, the potassium permanganate solution has a mass fraction of 10%; the ultrasonic power for the ultrasonic conditioning treatment is 350W, and the ultrasonic treatment lasts for 20 minutes.

[0077] The preparation method of the conditioning solution in this embodiment is as follows: S02a: Silane coupling agent KH550, 85% ethanol solution and β-cyclodextrin are mixed evenly at a mass ratio of 2:7:1 to obtain silane solution; S02b: 2 parts graphene, 1 part sodium dodecylbenzenesulfonate solution and 5 parts silane solution are mixed evenly, and then 3 parts silica are added and mixed thoroughly to obtain graphene-based solution; S02c: 3 parts silicon carbide whiskers, 2 parts lanthanum oxide and 1 part hydroxyapatite are blended and sintered for 1 hour. After sintering, a sintered body is obtained. The sintered body and graphene-based liquid are stirred thoroughly at a weight ratio of 3:5 to obtain a conditioning liquid.

[0078] The sintering temperature for the blending in this embodiment is 300°C; the mass fraction of the sodium dodecylbenzenesulfonate solution is 5%.

[0079] Nano SiO in this embodiment The modification process also employs a stirring treatment with a modified liquid. The specific modification method is as follows: S11: Mix 2 parts of 4% yttrium nitrate solution, 1 part of boron nitride and 3 parts of nanocellulose evenly to obtain yttrium solution; stir the yttrium solution, additives and sodium alginate solution in a weight ratio of 3:2:4 to obtain modified solution. S12: SiO Preheat at 60℃ for 1 hour, then preheat the SiO2. The modified liquid is stirred at a weight ratio of 5:8 for modification treatment. After stirring, it is filtered and dried. The additive is prepared by mixing nano-chromium oxide, Nb powder and zirconium powder in a weight ratio of 2:2:2.

[0080] In this embodiment, the sodium alginate solution has a mass fraction of 8%; the stirring speed for the stirring modification treatment is 450 r / min, and the stirring time is 1 h.

[0081] Optimization Example 2: Ti also undergoes conditioning processing, specifically the following methods: S01: Stir Ti powder in a sufficient amount of potassium permanganate solution, then wash with water, filter and dry. Heat the dried Ti powder at 220℃ for 1 hour, then cool it down to 60℃ at a rate of 5℃ / min and keep it at that temperature. S02: Ultrasonically treat the Ti powder and conditioning solution of S01 at a weight ratio of 5:11. After treatment, filter and dry.

[0082] In this embodiment, the potassium permanganate solution has a mass fraction of 15%; the ultrasonic power for the ultrasonic conditioning treatment is 400W, and the ultrasonic treatment lasts for 30 minutes.

[0083] The preparation method of the conditioning solution in this embodiment is as follows: S02a: Silane coupling agent KH550, 90% ethanol solution and β-cyclodextrin are mixed evenly at a mass ratio of 5:7:3 to obtain silane solution; S02b: 4 parts graphene, 3 parts sodium dodecylbenzenesulfonate solution and 8 parts silane solution are mixed evenly, and then 5 parts silica are added and mixed evenly to obtain graphene-based solution. S02c: 5 parts silicon carbide whiskers, 3 parts lanthanum oxide and 2 parts hydroxyapatite are blended and sintered for 1 hour. After sintering, a sintered body is obtained. The sintered body and graphene-based liquid are stirred thoroughly at a weight ratio of 3:8 to obtain a conditioning liquid.

[0084] The sintering temperature for the blending in this embodiment is 350°C; the sodium dodecylbenzenesulfonate solution has a mass fraction of 10%.

[0085] Nano SiO in this embodiment The modification process also employs a stirring treatment with a modified liquid. The specific modification method is as follows: S11: Mix 5 parts of 4% yttrium nitrate solution, 3 parts of boron nitride and 5 parts of nanocellulose evenly to obtain yttrium solution; stir the yttrium solution, additives and sodium alginate solution in a weight ratio of 5:2:6 to obtain modified solution. S12: SiO Preheating at 65℃ for 1 hour, then preheating the SiO2... The modified liquid is stirred at a weight ratio of 5:11 for modification treatment. After stirring, it is filtered and dried. The additive is prepared by mixing nano-chromium oxide, Nb powder and zirconium powder in a weight ratio of 4:3:2.

[0086] In this embodiment, the sodium alginate solution has a mass fraction of 12%; the stirring speed for the stirring modification treatment is 550 r / min, and the stirring time is 1 h.

[0087] Optimization Example 3: Ti also undergoes conditioning processing, specifically the following methods: S01: Stir Ti powder in a sufficient amount of potassium permanganate solution, then wash with water, filter and dry. Heat the dried Ti powder at 215℃ for 1 hour, then cool it down to 58℃ at a rate of 4℃ / min and keep it at that temperature. S02: Ultrasonically treat the Ti powder and conditioning solution of S01 at a weight ratio of 5:10. After treatment, filter and dry.

[0088] In this embodiment, the potassium permanganate solution has a mass fraction of 12.5%; the ultrasonic power for the ultrasonic conditioning treatment is 375W, and the ultrasonic treatment lasts for 25 minutes.

[0089] The preparation method of the conditioning solution in this embodiment is as follows: S02a: Silane coupling agent KH550, 88% ethanol solution and β-cyclodextrin are mixed evenly at a mass ratio of 3.5:7:2 to obtain silane solution; S02b: 3 parts graphene, 2 parts sodium dodecylbenzenesulfonate solution and 6.5 parts silane solution are mixed evenly, and then 4 parts silica are added and mixed evenly to obtain graphene-based solution. S02c: 4 parts silicon carbide whiskers, 2.5 parts lanthanum oxide and 1.5 parts hydroxyapatite are blended and sintered for 1 hour. After sintering, a sintered body is obtained. The sintered body and graphene-based liquid are stirred thoroughly at a weight ratio of 3:6.5 to obtain a conditioning solution.

[0090] The sintering temperature of the blend in this embodiment is 325°C; the mass fraction of the sodium dodecylbenzenesulfonate solution is 7.5%.

[0091] Nano SiO in this embodiment The modification process also employs a stirring treatment with a modified liquid. The specific modification method is as follows: S11: Mix 3.5 parts of 4% yttrium nitrate solution, 2 parts of boron nitride and 4 parts of nanocellulose evenly to obtain yttrium solution; stir the yttrium solution, additives and sodium alginate solution at a weight ratio of 4:2:5 to obtain modified solution. S12: SiO Preheating at 62℃ for 1 hour, then preheating the SiO2... The modified liquid is stirred at a weight ratio of 5:9 for modification treatment. After stirring, it is filtered and dried. The additive is prepared by mixing nano-chromium oxide, Nb powder and zirconium powder in a weight ratio of 3:2:2.

[0092] In this embodiment, the sodium alginate solution has a mass fraction of 10%; the stirring speed for the stirring modification treatment is 500 r / min, and the stirring time is 1 h.

[0093] Further investigation was conducted on the optimized products of Example 1-3, and the specific results are as follows:

[0094] As can be seen from Optimization Examples 1-3, based on Example 2, the Ti of the product in this invention undergoes conditioning treatment and nano-SiO2 processing. The product's performance was further improved by using a modified liquid stirring modification treatment.

[0095] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

[0096] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A high-performance weathering steel, wherein the weathering steel comprises a weathering steel base material, characterized in that, The surface of the weathering steel substrate is coated with a protective coating; The protective coating contains the following raw materials by weight percentage: Cr 18-30%, Mo 1-4%, Si 2-5%, Al 1-6%, Ti 3-8%, B 0.5-1.5%, Nano-SiO 2-5%, balance Fe.

2. The high-performance weathering steel according to claim 1, characterized in that, The Ti is also subjected to modulation processing, specifically as follows: S01: Stir Ti powder in a sufficient amount of potassium permanganate solution, then wash with water, filter and dry. Heat the dried Ti powder at 210-220℃ for 1 hour, then cool it down to 55-60℃ at a rate of 3-5℃ / min and keep it at that temperature. S02: Sort the Ti powder and conditioning solution of S01 by ultrasonic treatment at a weight ratio of 5:(9-11). After treatment, filter and dry.

3. The high-performance weathering steel according to claim 2, characterized in that, The potassium permanganate solution has a mass fraction of 10-15%; the ultrasonic power of the ultrasonic conditioning treatment is 350-400W, and the ultrasonic treatment lasts for 20-30 minutes.

4. The high-performance weathering steel according to claim 2, characterized in that, The preparation method of the conditioning solution is as follows: S02a: Mix silane coupling agent KH550, 85-90% ethanol solution and β-cyclodextrin in a mass ratio of (2-5):7:(1-3) to obtain silane solution; SO2b: 2-4 parts graphene, 1-3 parts sodium dodecylbenzenesulfonate solution and 5-8 parts silane solution are mixed evenly, and then 3-5 parts silica are added and mixed evenly to obtain graphene-based solution. S02c: 3-5 parts silicon carbide whiskers, 2-3 parts lanthanum oxide and 1-2 parts hydroxyapatite are blended and sintered for 1 hour. After sintering, a sintered body is obtained. The sintered body and graphene-based liquid are stirred thoroughly at a weight ratio of 3:(5-8) to obtain a conditioning liquid.

5. The high-performance weathering steel according to claim 4, characterized in that, The sintering temperature for blending is 300-350℃; the mass fraction of sodium dodecylbenzenesulfonate solution is 5-10%.

6. The high-performance weathering steel according to claim 1, characterized in that, The nano-SiO The modification process also employs a stirring treatment with a modified liquid. The specific modification method is as follows: S11: Mix 2-5 parts of 4% yttrium nitrate solution, 1-3 parts of boron nitride and 3-5 parts of nanocellulose evenly to obtain yttrium solution; stir the yttrium solution, additives and sodium alginate solution in a weight ratio of (3-5):2:(4-6) thoroughly to obtain modified solution; S12: SiO Preheat at 60-65℃ for 1 hour, then preheat the SiO2. The modified liquid is stirred and modified at a weight ratio of 5:(8-11). After stirring, it is filtered and dried. The additive is prepared by mixing nano-chromium oxide, Nb powder and zirconium powder in a weight ratio of (2-4):(1-3):

2.

7. The high-performance weathering steel according to claim 6, characterized in that, The sodium alginate solution has a mass fraction of 8-12%; the stirring speed for the stirring modification treatment is 450-550 r / min, and the stirring time is 1 h.

8. A method for preparing a high-performance weathering steel as described in any one of claims 1-7, characterized in that, Includes the following steps: S1. Substrate pretreatment: The weathering steel substrate is sandblasted to achieve a cleanliness level of Sa2.5 and a surface roughness Ra of 5.0-8.0μm, and then cleaned and activated. S2. Spray coating: Using atmospheric plasma spraying process, the alloy powder of the composition described in claim 1 is sprayed onto the surface of the treated substrate to form a coating with a thickness of 150-400μm. S3, Nitriding-Oxidation Treatment: The sprayed coating is subjected to low-temperature nitriding treatment and subsequent oxidation treatment in sequence.

9. The method for preparing high-performance weathering steel according to claim 8, characterized in that, The The low-temperature nitriding process involves holding the gas at 500-580℃ for 2-4 hours in a mixed atmosphere of nitrogen and hydrogen with a volume ratio of 1:

3. The subsequent oxidation treatment is as follows: in a humid air atmosphere with a relative humidity of 60-80%, heat at 600-700℃ for 1-3 hours; In step S1, the sandblasting roughening uses 0.8-1.2mm alloy steel grit and the compressed air pressure is 0.6-0.7MPa; the cleaning and activation involves blowing with 0.1MPa compressed air and then ultrasonically cleaning with 300W anhydrous ethanol for 5-10 minutes. In step S2, the parameters for atmospheric plasma spraying are as follows: the plasma gas is a mixture of Ar and hydrogen, the Ar gas flow rate is 40-60 L / min, and the hydrogen gas flow rate is 5-8 L / min; the spraying current is 400-500 A, and the voltage is 60-80 V; the spraying distance is 150-200 mm; the powder feeding rate is 25-40 g / min; and compressed air is used for side-blowing cooling during the spraying process to control the coating surface temperature to ≤300℃. After step S3, step S4, sealing treatment, is also included: using vacuum impregnation, the coating is impregnated with siloxane resin containing 8-12wt% molybdate corrosion inhibitor, the vacuum degree is -0.08 to -0.09MPa, the impregnation time is 15-20 minutes, and then cured at 120-150℃ for 2-3 hours.

10. The application of a high-performance weathering steel as described in any one of claims 1-8 in bridges.

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