Corrosion-resistant steel casting for bridge and preparation process of corrosion-resistant steel casting

Abstract

The invention discloses a corrosion-resistant steel casting for a bridge and a preparation process thereof, and relates to the technical field of steel castings, the preparation process comprises the following steps: S1, carrying out pretreatment, hot-dip galvanizing and pulse electrodeposition post-treatment on the surface of the steel casting to obtain a steel casting matrix; s2, the surface of a steel casting base body is evenly coated with the corrosion-resistant coating, drying is conducted for 48 h at the room temperature, and a corrosion-resistant steel casting is obtained; the corrosion-resistant coating is prepared from the following components: a silane coupling agent KH-560, an ethanol water solution, an amino trimethylene phosphonic acid modified ternary hybrid, water-borne epoxy resin, a wetting agent and a defoaming agent.

Description

Technical Field

[0001] The present invention relates to the technical field of steel castings, and particularly to a corrosion-resistant steel casting for bridges and its preparation process. Background Art

[0002] Bridge steel castings are long-term exposed to harsh environments such as humidity and salt spray, and are prone to electrochemical corrosion, seriously affecting the structural safety and service life. Traditional protection means such as hot-dip galvanizing can provide certain protection, but the zinc layer is prone to form loose corrosion products in the corrosive medium, resulting in the failure of protection. Although chromate conversion coatings have excellent self-healing properties, their high toxicity and serious environmental pollution have gradually been restricted from use. In recent years, waterborne epoxy resins have been widely studied due to their environmental friendliness and good adhesion, but microcracks and pores are easily generated during their curing process, providing channels for the penetration of corrosive media.

[0003] In the prior art, the introduction of nano-fillers (such as boron nitride, graphene) can improve the barrier performance of the coating, but the nano-particles are prone to agglomeration and have poor dispersibility, making it difficult to fully play their advantages. Therefore, it is of great significance to invent a corrosion-resistant steel casting for bridges. Summary of the Invention

[0004] The purpose of the present invention is to provide a corrosion-resistant steel casting for bridges and its preparation process to solve the problems raised in the prior art.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A preparation process of a corrosion-resistant steel casting for bridges includes the following steps: S1: Pretreat the surface of the steel casting, perform hot-dip galvanizing, and then perform post-treatment by pulse electro-deposition to obtain a matrix of the cast steel part;

[0007] S2: Uniformly coat the corrosion-resistant coating on the surface of the matrix of the cast steel part, and dry it at room temperature for 48 h to obtain a corrosion-resistant steel casting;

[0008] Further, the corrosion-resistant coating is composed of the following components: silane coupling agent KH-560, ethanol aqueous solution, amino trimethylene phosphonic acid modified ternary hybrid, waterborne epoxy resin, wetting agent, defoaming agent.

[0009] Further, the volume ratio of absolute ethanol to deionized water in the ethanol aqueous solution is 10∶16.7;

[0010] Further, the wetting agent is polyether modified silicone, and the model is EH-3290;

[0011] Further, the defoaming agent is an organosilicon synthetic defoaming agent, and the model is DU-966;

[0012] Further, in the process of pulse electro-deposition, the parameters include: the chemical treatment solution is prepared by dissolving 95 g of imidazole in 1 L of deionized water, and the electrolyte conductivity is 238 μs.cm -1 , the pulse frequency is 10 Hz, the pulse duty cycle is 1, the pulse on-time is 1 ms, the reverse pulse on-time is 1 ms, the peak voltage is 6 V, and the electro-deposition time is 2 - 6 h.

[0013] Further, the preparation method of the corrosion-resistant coating includes the following steps: adding the silane coupling agent KH-560 into an ethanol aqueous solution, adding an amino trimethylene phosphonic acid-modified ternary hybrid, ultrasonically dispersing for 2 - 2.5 h, adding a waterborne epoxy resin, a wetting agent, and an antifoaming agent, and stirring evenly to obtain the corrosion-resistant coating.

[0014] Further, in the preparation process of the corrosion-resistant coating, the proportion of each component by mass includes: 7.1 - 7.3 parts of the silane coupling agent KH-560, 25 - 26 parts of the ethanol aqueous solution, 0.03 - 0.05 parts of the amino trimethylene phosphonic acid-modified ternary hybrid, 30 - 35 parts of the waterborne epoxy resin, 0.5 - 0.6 parts of the wetting agent, and 0.3 - 0.4 parts of the antifoaming agent.

[0015] Further, the preparation method of the amino trimethylene phosphonic acid-modified ternary hybrid includes the following steps: adding the p-aminobenzoic acid-modified ternary hybrid into a 1 mol / L aqueous solution of amino trimethylene phosphonic acid, adding hydrochloric acid to adjust the pH to 1, ultrasonically treating for 1 - 1.5 h, adding aniline, ultrasonically dispersing, dissolving ammonium persulfate in a 1 mol / L aqueous solution of amino trimethylene phosphonic acid, slowly adding it drop by drop at a rate of 1 drop every 3 seconds, controlling the reaction temperature at 1 - 5 °C, with a reaction time of 8 - 8.5 h, centrifuging, washing the product with deionized water, and vacuum drying at 60 - 65 °C to obtain the amino trimethylene phosphonic acid-modified ternary hybrid;

[0016] Further, in the preparation process of the amino trimethylene phosphonic acid-modified ternary hybrid, 100 mL of a 1 mol / L aqueous solution of amino trimethylene phosphonic acid is used for every 0.1 g of the p-aminobenzoic acid-modified ternary hybrid, and the mass ratio of the p-aminobenzoic acid-modified ternary hybrid∶aniline∶ammonium persulfate is 0.1∶0.2∶0.48.

[0017] Further, the preparation method of the p-aminobenzoic acid-modified ternary hybrid includes the following steps: adding the ternary hybrid into an anhydrous ethanol solution of 1 mol / L p-aminobenzoic acid, adding sulfuric acid as a catalyst, heating to 50 - 55 °C and ultrasonically dispersing for 1 - 1.5 h, heating to 60 - 62 °C and reacting for 2 - 2.5 h, centrifuging, washing the product with deionized water, and vacuum drying at 60 - 65 °C to obtain the p-aminobenzoic acid-modified ternary hybrid;

[0018] Further, in the preparation process of the p-aminobenzoic acid modified ternary hybrid, 100 mL of an anhydrous ethanol solution of 1 mol / L p-aminobenzoic acid is used for every 0.1 g of the ternary hybrid.

[0019] Further, the preparation method of the ternary hybrid includes the following steps: adding the ZIF-8 supported boron nitride hydroxide nanosheets into methanol, ultrasonically dispersing, adding a 0.5 wt% phytic acid solution, stirring at room temperature for 30 - 35 min, filtering, washing the product with methanol, and drying in vacuum at 60 - 65 °C to obtain the ternary hybrid;

[0020] Further, in the preparation process of the ternary hybrid, the mass ratio of the ZIF-8 supported boron nitride hydroxide nanosheets to the 0.5 wt% phytic acid solution is 1.5∶(10 - 15).

[0021] Further, the preparation method of the ZIF-8 supported boron nitride hydroxide nanosheets includes the following steps: adding boron nitride hydroxide nanosheets, zinc nitrate hexahydrate, 2-methylimidazole, and 2-mercaptobenzimidazole into methanol respectively, stirring evenly to prepare a boron nitride hydroxide nanosheet suspension, a zinc nitrate hexahydrate solution, a 2-methylimidazole solution, and a 2-mercaptobenzimidazole solution. Adding 2-mercaptobenzimidazole into the zinc nitrate hexahydrate solution, stirring evenly, adding the mixed solution into the boron nitride hydroxide nanosheet suspension, stirring evenly, adding the 2-methylimidazole solution, stirring and reacting at room temperature for 8 - 9 h, centrifuging, washing the product with methanol, and drying in vacuum at 50 - 55 °C to obtain the ZIF-8 supported boron nitride hydroxide nanosheets;

[0022] Further, in the preparation process of the ZIF-8 supported boron nitride hydroxide nanosheets, the concentration of the boron nitride hydroxide nanosheet suspension is 0.1 - 0.15 g / 30 mL, the concentration of the zinc nitrate hexahydrate solution is 1 - 1.2 g / 20 mL, the concentration of the 2-methylimidazole solution is 2.2 - 2.4 g / 20 mL, and the concentration of the 2-mercaptobenzimidazole solution is 0.8 - 0.9 g / 30 mL;

[0023] Further, the preparation method of the boron nitride hydroxide nanosheets includes the following steps: adding hexagonal boron nitride into an isopropyl alcohol aqueous solution with a volume ratio of 55∶45, ultrasonically treating to obtain boron nitride nanosheets; adding the boron nitride nanosheets into a 5 M sodium hydroxide solution, ultrasonically dispersing, heating to 110 - 115 °C and reacting for 18 - 20 h, washing the product with deionized water, and drying in vacuum at 80 - 85 °C for 5 - 6 h to obtain the boron nitride hydroxide nanosheets.

[0024] Further, the thickness of the zinc layer in the hot-dip galvanizing is 50 - 150 μm, and the thickness of the corrosion-resistant coating is 5 - 10 μm.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] 1. The present invention constructs a uniform and dense ZIF-8 conversion coating on the surface of a hot-dip galvanized layer through a pulse electro-deposition process. This process regulates the release rate of zinc ions through a periodic reverse current, promotes the oriented growth of ZIF-8 crystals, and forms a porous and continuous coating structure. The layered pore structure of ZIF-8 significantly prolongs the penetration path of corrosive media (Cl - , H2O), and its surface hydroxylation treatment further enhances the interfacial bonding force with the epoxy coating. In the initial stage of corrosion, the local slightly acidic environment triggers the pH-responsive disintegration of ZIF-8, releasing zinc ions (Zn 2+ ) and 2-methylimidazole. The free Zn 2+ reacts with OH - in the corrosive medium to form Zn(OH)2 precipitate, covering the microdefects on the metal surface and inhibiting anodic dissolution (Reference 2). At the same time, 2-methylimidazole molecules adsorb on the metal surface and form a physical barrier through π-π interactions, delaying the corrosion process.

[0027] 2. The composite structure of ZIF-8 and h-BN-OH is arranged in parallel in the coating through the lamellar structure of h-BN-OH, forming a "labyrinth effect" with the pores of ZIF-8, greatly prolonging the diffusion path of corrosive media and forming a physical barrier; at the same time, the slow-release Zn 2+ of ZIF-8 and the chelation of ATMP form a double protective layer, and the doping of phytic acid further promotes the crosslinking density of epoxy resin, improving the hardness and impact resistance of the coating, and having a chemical synergistic corrosion inhibition effect.

[0028] 3. The present invention further graft-modifies ZIF-8 loaded with hydroxyboron nitride nanosheets modified by aminotrimethylenephosphonic acid to phytic acid, introducing aminotrimethylenephosphonic acid into the structure. Utilizing its metal chelating effect, aminotrimethylenephosphonic acid contains multiple phosphonic acid groups (-PO(OH)2). When ZIF-8 disintegrates and releases Zn 2+ , it quickly forms a stable six-membered ring chelate with it. This complex adsorbs on the active sites of the metal surface, covering microcracks and pores, and preventing the diffusion of corrosive media. In the damaged area of the coating, aminotrimethylenephosphonic acid preferentially captures Zn 2+ through chelation, promoting the formation of dense passivation films such as Zn(OH)2 and Zn3(PO4)2, realizing local self-repair, and further improving the corrosion resistance. Specific Embodiments

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] In the following embodiments, the preparation method of hydroxyboron nitride nanosheets comprises the following steps: adding 1 g of hexagonal boron nitride into 100 mL of an isopropanol aqueous solution with a volume ratio of 55:45, performing ultrasonic treatment to obtain boron nitride nanosheets; adding 1 g of boron nitride nanosheets into 10 mL of a 5M sodium hydroxide solution, performing ultrasonic dispersion, heating to 110 °C and reacting for 18 h, washing the product with deionized water, and drying in vacuum at 80 °C for 5 h to obtain hydroxyboron nitride nanosheets.

[0031] The preparation method of ZIF-8 supported hydroxyboron nitride nanosheets comprises the following steps: adding 0.1 g of hydroxyboron nitride nanosheets, 1 g of zinc nitrate hexahydrate, 2.2 g of 2-methylimidazole, and 0.8 g of 2-mercaptobenzimidazole into 30 mL of methanol, 20 mL of methanol, 20 mL of methanol, and 30 mL of methanol respectively, stirring evenly to prepare a hydroxyboron nitride nanosheet suspension, a zinc nitrate hexahydrate solution, a 2-methylimidazole solution, and a 2-mercaptobenzimidazole solution; adding 2-mercaptobenzimidazole into the zinc nitrate hexahydrate solution, stirring evenly, adding the mixed solution into the hydroxyboron nitride nanosheet suspension, stirring evenly, adding the 2-methylimidazole solution, stirring and reacting at room temperature for 8 h, centrifuging, washing the product with methanol, and drying in vacuum at 50 °C to obtain ZIF-8 supported hydroxyboron nitride nanosheets;

[0032] The preparation method of the ternary hybrid comprises the following steps: adding 1.5 g of ZIF-8 supported hydroxyboron nitride nanosheets into methanol, performing ultrasonic dispersion, adding 15 g of a 0.5 wt% phytic acid solution, stirring at room temperature for 30 min, filtering, washing the product with methanol, and drying in vacuum at 60 °C to obtain the ternary hybrid;

[0033] The preparation method of p-aminobenzoic acid modified ternary hybrid comprises the following steps: adding 0.1 g of the ternary hybrid into 100 mL of an anhydrous ethanol solution of 1 mol / L p-aminobenzoic acid, adding sulfuric acid as a catalyst, heating to 50 °C and performing ultrasonic dispersion for 1 h, heating to 60 °C and reacting for 2 h, centrifuging, washing the product with deionized water, and drying in vacuum at 60 °C to obtain the p-aminobenzoic acid modified ternary hybrid;

[0034] Preparation method of amino trimethylene phosphonic acid modified ternary hybrid, comprising the following steps: adding 0.1 g of p-aminobenzoic acid modified ternary hybrid into 100 mL of 1 mol / L amino trimethylene phosphonic acid aqueous solution, adding hydrochloric acid to adjust the pH to 1, performing ultrasonic treatment for 1 h, adding 0.2 g of aniline, performing ultrasonic dispersion, dissolving 0.48 g of ammonium sulfate in 30 mL of 1 mol / L amino trimethylene phosphonic acid aqueous solution, slowly adding it at a rate of 1 drop every 3 seconds, controlling the reaction temperature at 1 - 5 °C, with a reaction time of 8 h, centrifuging, washing the product with deionized water, and drying it in vacuum at 60 °C to obtain the amino trimethylene phosphonic acid modified ternary hybrid.

[0035] Example 1: Preparation process of a corrosion-resistant steel casting for bridges, comprising the following preparation process: S1: Pretreating the surface of the steel casting, immersing the steel casting in molten zinc at 450 °C for hot dip galvanizing, with a zinc layer thickness of 100 μm, followed by post-treatment of pulse electro-deposition to obtain the steel casting substrate;

[0036] During the process of pulse electro-deposition, the parameters include: the chemical treatment solution is prepared by dissolving 95 g of imidazole in 1 L of deionized water, and the electrolyte conductivity is 238 μs.cm -1 , the pulse frequency is 10 Hz, the pulse duty cycle is 1, the pulse on-time is 1 ms, the reverse pulse on-time is 1 ms, the peak voltage is 6 V, and the electro-deposition time is 4 h;

[0037] S2: Adding 7.1 parts of silane coupling agent KH-560 into 25 parts of ethanol aqueous solution, adding 0.03 parts of amino trimethylene phosphonic acid modified ternary hybrid, performing ultrasonic dispersion for 2 h, adding 30 parts of waterborne epoxy resin, 0.5 part of wetting agent, and 0.3 part of defoaming agent, and stirring evenly to obtain the corrosion-resistant coating;

[0038] S3: Uniformly coating the corrosion-resistant coating on the surface of the steel casting substrate, with a thickness of the corrosion-resistant coating of 10 μm, and drying at room temperature for 48 h to obtain the corrosion-resistant steel casting.

[0039] Example 2: Preparation process of a corrosion-resistant steel casting for bridges, comprising the following preparation process: S1: Pretreating the surface of the steel casting, immersing the steel casting in molten zinc at 450 °C for hot dip galvanizing, with a zinc layer thickness of 100 μm, followed by post-treatment of pulse electro-deposition to obtain the steel casting substrate;

[0040] During the process of pulse electro-deposition, the parameters include: the chemical treatment solution is prepared by dissolving 95 g of imidazole in 1 L of deionized water, and the electrolyte conductivity is 238 μs.cm -1 , the pulse frequency is 10 Hz, the pulse duty cycle is 1, the pulse on-time is 1 ms, the reverse pulse on-time is 1 ms, the peak voltage is 6 V, and the electro-deposition time is 4 h;

[0041] S2: Add 7.1 parts of silane coupling agent KH-560 into 25 parts of ethanol aqueous solution, add 0.04 part of amino trimethylene phosphonic acid modified ternary hybrid, ultrasonically disperse for 2 h, add 30 parts of waterborne epoxy resin, 0.5 part of wetting agent, and 0.3 part of defoaming agent, and stir evenly to obtain the corrosion-resistant coating;

[0042] S3: Uniformly coat the corrosion-resistant coating on the surface of the cast steel part substrate, with the thickness of the corrosion-resistant coating being 10 μm, and dry at room temperature for 48 h to obtain the corrosion-resistant steel casting.

[0043] Example 3: A preparation process of a corrosion-resistant steel casting for bridges, including the following preparation process: S1: Pretreat the surface of the steel casting, immerse the steel casting in molten zinc at 450 °C for hot dip galvanizing, with the zinc layer thickness being 100 μm, and perform post-treatment by pulse electro-deposition to obtain the cast steel part substrate;

[0044] During the process of pulse electro-deposition, the parameters include: the chemical treatment solution is prepared by dissolving 95 g of imidazole in 1 L of deionized water, the conductivity of the electrolyte is 238 μs.cm -1 , the pulse frequency is 10 Hz, the pulse duty cycle is 1, the pulse on-time is 1 ms, the reverse pulse on-time is 1 ms, the peak voltage is 6 V, and the electro-deposition time is 4 h;

[0045] S2: Add 7.1 parts of silane coupling agent KH-560 into 25 parts of ethanol aqueous solution, add 0.05 part of amino trimethylene phosphonic acid modified ternary hybrid, ultrasonically disperse for 2 h, add 30 parts of waterborne epoxy resin, 0.5 part of wetting agent, and 0.3 part of defoaming agent, and stir evenly to obtain the corrosion-resistant coating;

[0046] S3: Uniformly coat the corrosion-resistant coating on the surface of the cast steel part substrate, with the thickness of the corrosion-resistant coating being 10 μm, and dry at room temperature for 48 h to obtain the corrosion-resistant steel casting.

[0047] Comparative Example 1: A preparation process of a corrosion-resistant steel casting for bridges, including the following preparation process: S1: Add 1 g of hexagonal boron nitride into 100 mL of isopropyl alcohol aqueous solution with a volume ratio of 55v45, and perform ultrasonic treatment to obtain boron nitride nanosheets; add 1 g of boron nitride nanosheets into 10 mL of 5M sodium hydroxide solution, ultrasonically disperse, heat to 110 °C and react for 18 h, wash the product with deionized water, and vacuum dry at 80 °C for 5 h to obtain hydroxy boron nitride nanosheets.

[0048] S2: Add 0.1 g of hydroxyboron nitride nanosheets, 1 g of zinc nitrate hexahydrate, 2.2 g of 2-methylimidazole, and 0.8 g of 2-mercaptobenzimidazole into 30 mL of methanol, 20 mL of methanol, 20 mL of methanol, and 30 mL of methanol respectively, stir evenly to prepare a hydroxyboron nitride nanosheet suspension, a zinc nitrate hexahydrate solution, a 2-methylimidazole solution, and a 2-mercaptobenzimidazole solution. Add 2-mercaptobenzimidazole into the zinc nitrate hexahydrate solution, stir evenly, add the mixed solution into the hydroxyboron nitride nanosheet suspension, stir evenly, add the 2-methylimidazole solution, stir and react at room temperature for 8 h, centrifuge, wash the product with methanol, and dry it in vacuum at 50 °C to obtain ZIF-8 supported hydroxyboron nitride nanosheets;

[0049] S3: Add 1.5 g of ZIF-8 supported hydroxyboron nitride nanosheets into methanol, disperse them by ultrasonic wave, add 15 g of 0.5 wt% phytic acid solution, stir at room temperature for 30 min, filter, wash the product with methanol, and dry it in vacuum at 60 °C to obtain a ternary hybrid;

[0050] S4: Pretreat the surface of the steel casting, immerse the steel casting in molten zinc at 450 °C for hot-dip galvanizing, with a zinc layer thickness of 100 μm, and perform post-treatment by pulsed electro-deposition to obtain a steel casting substrate;

[0051] In the process of pulsed electro-deposition, the parameters include: the chemical treatment solution is prepared by dissolving 95 g of imidazole in 1 L of deionized water, the electrolyte conductivity is 238 μs.cm -1 , the pulse frequency is 10 Hz, the pulse duty cycle is 1, the pulse on-time is 1 ms, the reverse pulse on-time is 1 ms, the peak voltage is 6 V, and the electro-deposition time is 4 h;

[0052] S5: Add 7.1 parts of silane coupling agent KH-560 into 25 parts of ethanol aqueous solution, add 0.03 parts of the ternary hybrid, disperse them by ultrasonic wave for 2 h, add 30 parts of waterborne epoxy resin, 0.5 part of wetting agent, and 0.3 part of defoaming agent, and stir evenly to obtain a corrosion-resistant coating;

[0053] S6: Uniformly coat the corrosion-resistant coating on the surface of the steel casting substrate, with the thickness of the corrosion-resistant coating being 10 μm, and dry it at room temperature for 48 h to obtain a corrosion-resistant steel casting.

[0054] Comparative Example 2: A preparation process for a corrosion-resistant steel casting for bridges, including the following preparation process: S1: Pretreat the surface of the steel casting, immerse the steel casting in molten zinc at 450 °C for hot-dip galvanizing, with a zinc layer thickness of 100 μm, to obtain a steel casting substrate;

[0055] S2: Add 7.1 parts of silane coupling agent KH-560 to 25 parts of ethanol aqueous solution, add 0.03 part of amino trimethylene phosphonic acid modified ternary hybrid, disperse ultrasonically for 2 h, add 30 parts of waterborne epoxy resin, 0.5 part of wetting agent, and 0.3 part of defoaming agent, stir evenly to obtain the corrosion-resistant coating;

[0056] S3: Evenly coat the corrosion-resistant coating on the surface of the cast steel substrate, with the thickness of the corrosion-resistant coating being 10 μm, and dry at room temperature for 48 h to obtain the corrosion-resistant steel casting.

[0057] Comparative Example 1: A preparation process for a corrosion-resistant steel casting for bridges, including the following preparation process:

[0058] S1: Add 1 g of hexagonal boron nitride to 100 mL of isopropanol aqueous solution with a volume ratio of 55:45, perform ultrasonic treatment to obtain boron nitride nanosheets; add 1 g of boron nitride nanosheets to 10 mL of 5M sodium hydroxide solution, disperse ultrasonically, heat to 110 °C and react for 18 h, wash the product with deionized water, and dry in vacuum at 80 °C for 5 h to obtain hydroxy boron nitride nanosheets.

[0059] S2: Pretreat the surface of the steel casting, immerse the steel casting in molten zinc at 450 °C for hot-dip galvanizing, with the zinc layer thickness being 100 μm, and perform post-treatment by pulse electro-deposition to obtain the cast steel substrate;

[0060] In the process of pulse electro-deposition, the parameters include: the chemical treatment solution is prepared by dissolving 95 g of imidazole in 1 L of deionized water, the electrolyte conductivity is 238 μs.cm -1 , the pulse frequency is 10 Hz, the pulse duty cycle is 1, the pulse on-time is 1 ms, the reverse pulse on-time is 1 ms, the peak voltage is 6 V, and the electro-deposition time is 4 h;

[0061] S3: Add 7.1 parts of silane coupling agent KH-560 to 25 parts of ethanol aqueous solution, add 0.03 part of hydroxy boron nitride nanosheets, disperse ultrasonically for 2 h, add 30 parts of waterborne epoxy resin, 0.5 part of wetting agent, and 0.3 part of defoaming agent, stir evenly to obtain the corrosion-resistant coating;

[0062] S4: Evenly coat the corrosion-resistant coating on the surface of the cast steel substrate, with the thickness of the corrosion-resistant coating being 10 μm, and dry at room temperature for 48 h to obtain the corrosion-resistant steel casting.

[0063] Experiment: Adhesion performance test: Test by a cupping tester conforming to ISO 1520 standard. Before the test, make 2×2 mm grid scratches on the surface of the specimen, and observe the changes of the specimen through a 10-fold magnifying glass during the test. All performance test experiments are repeated at least 3 times, and observe the scratch depth at which coating peeling occurs.

[0064] Corrosion resistance performance test: Using an electrochemical workstation, manually make 2×2 mm grid scratches on the coating surface, then immerse it in 3.5 wt.% NaCl solution for 24 h, with a frequency range from 100 kHz to 10 mHz, and adopt a three - electrode system (saturated calomel electrode, platinum electrode, working electrode). By analyzing the Nyquist and Bode diagrams, calculate the impedance modulus (Z) of the coating.

[0065] The experimental results are shown in Table 1 below.

[0066] Table 1 Data sheet for performance test of corrosion - resistant steel castings for bridges

[0067] <![CDATA[Impedance modulus / Ω·cm 2 > Scratch depth / mm Example 1 <![CDATA[1.37×10 4 > 6.5 Example 2 <![CDATA[5.89×10 4 > 7.2 Example 3 <![CDATA[8.78×10 4 > 7.9 Comparative Example 1 <![CDATA[5.22×10 3 > 4.9 Comparative Example 2 <![CDATA[7.21×10 3 > 5.5 Comparative Example 3 <![CDATA[1.21×10 3 > 4.5

[0068] Conclusion: The corrosion - resistant steel castings for bridges prepared by the present invention have excellent corrosion resistance performance and coating adhesion performance.

[0069] In Comparative Example 1, using a ternary hybrid to replace the amino - trimethylene - phosphonic acid - modified ternary hybrid results in a decrease in corrosion resistance performance and coating adhesion performance. In Comparative Example 2, lacking the post - treatment step of pulse electro - deposition leads to a decrease in corrosion resistance performance and coating adhesion performance. In Comparative Example 3, using hydroxy - boron nitride nanosheets to replace the amino - trimethylene - phosphonic acid - modified ternary hybrid results in a decrease in corrosion resistance performance and coating adhesion performance.

[0070] For those skilled in the art, it is obvious that the present invention is not limited to the details of the above - mentioned exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, in any regard, the embodiments should be regarded as exemplary and non - restrictive. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, it is intended to encompass all changes within the meaning and scope of the equivalent elements of the claims in the present invention.

Claims

1. A preparation process for corrosion-resistant steel castings for bridges, characterized in that: It includes the following preparation processes: S1: Pretreat the surface of the steel casting, perform hot-dip galvanizing, and then carry out post-treatment by pulse electrodeposition to obtain the matrix of the cast steel part; S2: Uniformly coat the corrosion-resistant coating on the surface of the cast steel part matrix and dry it at room temperature for 48 h to obtain the corrosion-resistant cast steel part; The corrosion-resistant coating is composed of the following components: silane coupling agent KH-560, ethanol aqueous solution, amino trimethylene phosphonic acid modified ternary hybrid, waterborne epoxy resin, wetting agent, defoaming agent.

2. The preparation process of a corrosion-resistant steel casting for a bridge according to claim 1, characterized in that: The process of the pulsed electroplating, the parameters include: the chemical treatment solution is prepared by dissolving 95 g of imidazole in 1 L of deionized water, and the conductivity of the electrolyte is 238 μs.cm -1 , the pulse frequency is 10 Hz, the pulse duty cycle is 1, the pulse-on time is 1 ms, the reverse pulse-on time is 1 ms, the peak voltage is 6 V, and the electroplating time is 2 - 6 h.

3. The preparation process of a corrosion-resistant steel casting for a bridge according to claim 1, characterized in that: The preparation method of the corrosion-resistant coating includes the following steps: Add the silane coupling agent KH-560 into the ethanol aqueous solution, add the amino trimethylene phosphonic acid modified ternary hybrid, perform ultrasonic dispersion for 2 - 2.5 h, add the waterborne epoxy resin, wetting agent, and defoaming agent, and stir evenly to obtain the corrosion-resistant coating; In the preparation process of the corrosion-resistant coating, the proportion of each component by mass fraction includes: 7.1 - 7.3 parts of silane coupling agent KH-560, 25 - 26 parts of ethanol aqueous solution, 0.03 - 0.05 parts of amino trimethylene phosphonic acid modified ternary hybrid, 30 - 35 parts of waterborne epoxy resin, 0.5 - 0.6 parts of wetting agent, and 0.3 - 0.4 parts of defoaming agent.

4. The preparation process of a corrosion-resistant steel casting for a bridge according to claim 3, characterized in that: The preparation method of the amino trimethylene phosphonic acid modified ternary hybrid includes the following steps: Add the p-aminobenzoic acid modified ternary hybrid into a 1 mol / L aqueous solution of amino trimethylene phosphonic acid, add hydrochloric acid to adjust the pH to 1, perform ultrasonic treatment for 1 - 1.5 h, add aniline, perform ultrasonic dispersion, dissolve ammonium persulfate in a 1 mol / L aqueous solution of amino trimethylene phosphonic acid, and slowly add it at a rate of 1 drop every 3 seconds. Control the reaction temperature at 1 - 5 °C, and the reaction time is 8 - 8.5 h. Centrifuge, wash the product with deionized water, and dry it in vacuum at 60 - 65 °C to obtain the amino trimethylene phosphonic acid modified ternary hybrid; In the preparation process of the amino trimethylene phosphonic acid modified ternary hybrid, 100 mL of 1 mol / L aqueous solution of amino trimethylene phosphonic acid is used for every 0.1 g of the p-aminobenzoic acid modified ternary hybrid, and the mass ratio of the p-aminobenzoic acid modified ternary hybrid: aniline: ammonium persulfate is 0.1:0.2:0.

48.

5. The preparation process of a corrosion-resistant steel casting for a bridge according to claim 4, characterized in that: The preparation method of the p-aminobenzoic acid modified ternary hybrid includes the following steps: Add the ternary hybrid into a 1 mol / L anhydrous ethanol solution of p-aminobenzoic acid, add sulfuric acid as a catalyst, heat to 50 - 55 °C and perform ultrasonic dispersion for 1 - 1.5 h, heat to 60 - 62 °C and react for 2 - 2.5 h. Centrifuge, wash the product with deionized water, and dry it in vacuum at 60 - 65 °C to obtain the p-aminobenzoic acid modified ternary hybrid; In the preparation process of the p-aminobenzoic acid modified ternary hybrid, 100 mL of 1 mol / L anhydrous ethanol solution of p-aminobenzoic acid is used for every 0.1 g of the ternary hybrid.

6. The preparation process of a corrosion-resistant steel casting for a bridge according to claim 5, characterized in that: The preparation method of the ternary hybrid includes the following steps: Add ZIF-8 supported hydroxyboron nitride nanosheets into methanol, perform ultrasonic dispersion, add a 0.5 wt% phytic acid solution, stir at room temperature for 30 - 35 min, filter, wash the product with methanol, and dry it in vacuum at 60 - 65 °C to obtain the ternary hybrid; During the preparation of the ternary hybrid, for the ZIF-8 supported boron nitride hydroxide nanosheets, the mass ratio of the 0.5 wt% phytic acid solution is 1.5:(10 - 15).

7. The preparation process of a corrosion-resistant steel casting for a bridge according to claim 6, characterized in that: The method for preparing the ZIF-8 supported boron nitride hydroxide nanosheets includes the following steps: Add boron nitride hydroxide nanosheets, zinc nitrate hexahydrate, 2-methylimidazole, and 2-mercaptobenzimidazole into methanol respectively, stir evenly to obtain a boron nitride hydroxide nanosheet suspension, a zinc nitrate hexahydrate solution, a 2-methylimidazole solution, and a 2-mercaptobenzimidazole solution. Add 2-mercaptobenzimidazole into the zinc nitrate hexahydrate solution, stir evenly, add the mixed solution into the boron nitride hydroxide nanosheet suspension, stir evenly, add the 2-methylimidazole solution, stir and react at room temperature for 8 - 9 h, centrifuge, wash the product with methanol, and dry it under vacuum at 50 - 55 °C to obtain the ZIF-8 supported boron nitride hydroxide nanosheets; During the preparation of the ZIF-8 supported boron nitride hydroxide nanosheets, the concentration of the boron nitride hydroxide nanosheet suspension is 0.1 - 0.15 g / 30 mL, the concentration of the zinc nitrate hexahydrate solution is 1 - 1.2 g / 20 mL, the concentration of the 2-methylimidazole solution is 2.2 - 2.4 g / 20 mL, and the concentration of the 2-mercaptobenzimidazole solution is 0.8 - 0.9 g / 30 mL.

8. The preparation process of a corrosion-resistant steel casting for a bridge according to claim 7, characterized in that: The method for preparing the boron nitride hydroxide nanosheets includes the following steps: Add hexagonal boron nitride into an isopropanol aqueous solution with a volume ratio of 55:45, perform ultrasonic treatment to obtain boron nitride nanosheets; add the boron nitride nanosheets into a 5 M sodium hydroxide solution, ultrasonically disperse, heat to 110 - 115 °C and react for 18 - 20 h, wash the product with deionized water, and dry it under vacuum at 80 - 85 °C for 5 - 6 h to obtain the boron nitride hydroxide nanosheets.

9. The preparation process of a corrosion-resistant steel casting for a bridge according to claim 1, characterized in that: The thickness of the zinc layer in the hot-dip galvanizing is 50 - 150 μm, and the thickness of the corrosion-resistant coating is 5 - 10 μm.

10. A corrosion-resistant steel casting prepared by the preparation process of a corrosion-resistant steel casting for bridges according to any one of claims 1 - 9.