A continuous processing technology for hot-dip galvanized steel sheets for marine vessels

Abstract

This application relates to the field of marine vessel material processing, specifically disclosing a continuous processing technology for hot-dip galvanized steel sheets for marine vessels, including the following steps: S1, several steel sheets are sequentially subjected to pretreatment, pickling, water washing, and flux treatment to obtain fluxed steel sheets; S2, several fluxed steel sheets are sequentially placed in a zinc plating solution for zinc plating treatment. As the number of steel sheets undergoing zinc plating increases, porous zinc ingots are added to the zinc plating solution to continue zinc plating treatment. During the zinc plating treatment, the aluminum content is maintained at 0.15-0.17% to obtain a semi-finished product; S3, several semi-finished products are sequentially cooled, passivated, and dried to obtain galvanized steel sheets. The process has advantages such as smooth surface, low roughness, corrosion resistance, good wear resistance, good sealing integrity, and resistance to seawater penetration.

Description

Technical Field

[0001] This application relates to the field of marine vessel material processing, and more specifically, it relates to a continuous processing technology for hot-dip galvanized steel sheets for marine vessels. Background Technology

[0002] With the continuous development of the shipping industry, the requirements for ship components are gradually increasing. The steel plate materials used in the hull and its components need to have good adhesion and durability, as well as high mechanical strength, to meet the safety and stability requirements of the shipping process.

[0003] However, steel plates are easily affected by oxidation in the natural environment, which can lead to rust and a rough, uneven surface. This not only affects the appearance and durability of the steel plate but also its service life. Therefore, to prevent steel plate oxidation, zinc is usually coated on the surface. Zinc has good anti-corrosion properties and can effectively protect the surface of the steel plate from oxidation by the external environment, thus playing a role in corrosion prevention and wear resistance.

[0004] During the processing of galvanized steel sheets, zinc needs to be replenished in a timely manner as it is gradually consumed. This is generally done by adding zinc ingots to the galvanizing bath. However, because melting zinc ingots requires a large amount of heat, it can easily lead to a localized drop in the temperature of the galvanizing bath, reducing the iron saturation and causing zinc dross to precipitate. Zinc dross is mainly an intermetallic compound formed by iron and zinc or aluminum. Zinc dross is divided into floating dross and bottom dross. When the effective aluminum content in the galvanizing bath is less than 0.135%, the density of the zinc dross is greater than that of the galvanizing bath, and it is called bottom dross. Conversely, when the effective aluminum content in the galvanizing bath is greater than 0.135%, the density of the zinc dross is less than that of the zinc bath. The liquid density is called slag. The presence of bottom slag easily leads to it adhering to the steel plate surface along with the zinc liquid during stirring, making the steel plate surface rough and uneven, and with poor stability. Therefore, zinc slag generally needs to exist in the form of slag, which can be removed in time, thereby reducing the impact of zinc slag on galvanized steel plates. If zinc slag is present, it will not only easily lead to a rough and uneven surface of galvanized steel plates, increasing repair costs, but also easily reduce the adhesion stability of the core layer, affecting the corrosion resistance, wear resistance and mechanical strength of galvanized steel plates, thus affecting the service life of galvanized steel plates.

[0005] Therefore, how to develop a new hot-dip galvanizing process for steel plates that can produce galvanized steel plates with advantages such as smooth surface, low roughness, corrosion resistance, good wear resistance, good sealing integrity and not easily permeable by seawater during continuous production, and which can be applied to marine ship materials, is a problem that needs to be solved. Summary of the Invention

[0006] In order to develop a new hot-dip galvanizing process for steel plates, which can produce galvanized steel plates with advantages such as smooth surface, low roughness, good corrosion resistance, good wear resistance, good sealing integrity and not easy to penetrate seawater during continuous production of galvanized steel plates, and can be applied to marine ship materials, this application provides a continuous processing technology for hot-dip galvanized steel plates for marine ships.

[0007] This application provides a continuous processing technology for hot-dip galvanized steel sheets used in marine vessels, which adopts the following technical solution: A continuous processing technology for hot-dip galvanized steel sheets used in marine vessels includes the following steps:

[0008] S1. Several steel plates are sequentially subjected to pretreatment, pickling, water washing, and flux treatment to obtain fluxed steel plates;

[0009] S2. Several steel sheets are placed in the zinc plating solution for zinc plating in sequence. As the number of steel sheets to be zinc plating increases, porous zinc ingots are added to the zinc plating solution to continue zinc plating. During the zinc plating process, the aluminum content is maintained at 0.15-0.17% to obtain a semi-finished product.

[0010] S3. Several semi-finished products are successively cooled, passivated, and dried to obtain galvanized steel sheets.

[0011] By adopting the above technical solution, the iron powder content on the surface of the steel plate is limited, resulting in a smoother and more uniform galvanized layer, reducing the likelihood of zinc particles and zinc scars. As the steel plate undergoes galvanizing, the zinc dross content in the galvanizing solution gradually increases. The addition of porous zinc ingots allows for rapid melting, and during the melting process, the ingots gradually break down from large pieces into smaller ones. These smaller pieces are evenly dispersed, preventing localized low temperatures in the galvanizing solution and ensuring a uniform galvanized layer thickness and good adhesion stability. Furthermore, the excellent corrosion resistance and water resistance of the galvanized layer ensure that each galvanized steel plate, during continuous production, possesses advantages such as a smooth surface, low roughness, good corrosion resistance, good wear resistance, and excellent sealing integrity, making it less susceptible to seawater penetration.

[0012] Preferably, the porous zinc ingot is prepared by the following method:

[0013] Large zinc ingots are broken into zinc blocks, then glycerol is sprayed evenly, followed by ammonium chloride and silicon carbide fiber. The mixture is stirred evenly, dried, and dispersed to obtain the finished porous zinc ingot.

[0014] By adopting the above technical solution, zinc blocks, glycerol, ammonium chloride and silicon carbide fibers are combined. The adhesiveness of glycerol makes it easy to adhere ammonium chloride and silicon carbide fibers to the surface of zinc blocks. Zinc blocks can also be connected to each other, so that large zinc ingots without pore structure can be processed into porous zinc ingots with pore structure and connecting gaps.

[0015] When porous zinc ingots are added to the galvanizing bath, the high temperature of the bath, combined with the thermal conductivity of silicon carbide fibers and the porosity of the ingots, promotes rapid disintegration and dispersion of the ingots. This facilitates uniform dispersion and rapid melting of the ingots, replenishing the zinc source for the galvanizing bath and minimizing the problem of localized temperature drops in the bath due to the addition of large ingots, which could affect the thickness and uniformity of the galvanized layer. Glycerol volatilizes at the high temperature of the galvanizing bath without affecting the galvanizing process of the steel plate, and the volatilized gas helps disperse the zinc ingots. Meanwhile, ammonium chloride has fluidity and dispersibility, further promoting the dispersion of zinc ingot particles, allowing the zinc ingots to rapidly disperse and melt while maintaining uniform contact with the steel plate. Moreover, the hydrogen gas produced by the thermal decomposition of ammonium chloride promotes rapid and convenient zinc deposition on the steel plate surface, increasing the zinc deposition rate and ensuring the uniformity of the galvanized layer. This results in a galvanized layer with a smooth surface, wear resistance, corrosion resistance, and seawater resistance.

[0016] Preferably, the preprocessing steps are as follows:

[0017] After washing, ethyl cellulose composite liquid is applied to the scratches and grooves on the steel plate surface, and then dried and polished until the steel plate surface is smooth and flat.

[0018] By adopting the above technical solution, the viscosity of the ethyl cellulose solution facilitates its adhesion to the scratches and grooves on the steel plate surface, allowing the scratches to be filled and providing good waterproof, high toughness, and high strength properties. The scratched surface needs to be polished to make the steel plate surface smooth and flat, ensuring the flatness of the steel plate surface, as well as the strength and toughness of the steel plate. At the same time, it facilitates the uniform and stable adhesion of the galvanized layer, improving the corrosion resistance, wear resistance, and mechanical strength of the galvanized steel plate. This ensures that the scratched steel pipe is not easily scrapped, thus reducing the company's costs.

[0019] Preferably, the ethyl cellulose composite solution is composed of an ethyl cellulose ethanol solution, iron powder, and polyetheretherketone microparticles in a mass ratio of 1:0.2-0.5:0.1-0.2.

[0020] By adopting the above technical solution, ethyl cellulose ethanol solution, iron powder, and polyether ether ketone are combined. The good adhesion effect of ethyl cellulose ethanol solution facilitates the adhesion of iron powder and polyether ether ketone to the outer layer of the scratched surface of the steel plate. The reaction between iron powder and zinc liquid improves the galvanizing effect at the scratched location. In addition, the bonding effect of ethyl cellulose and polyether ether ketone can improve the adhesion stability of the galvanized layer on the scratched surface. At the same time, the good strength and toughness of polyether ether ketone can give the galvanized steel plate high strength and good wear resistance and corrosion resistance.

[0021] Polyetheretherketone (PEEK) and ethyl cellulose are hot-melted at higher temperatures in the galvanizing bath, which improves the adhesion stability of the galvanized layer at the scratch location. Furthermore, ethyl cellulose and PEEK have good acid and alkali resistance and salt resistance, making them suitable for use in the manufacture of marine products. They can resist the corrosion of steel plates by seawater and marine microorganisms, thereby extending the service life of galvanized steel plates in the ocean.

[0022] Preferably, the acid solution used in the pickling process is a hydrochloric acid solution with a concentration of 50-65%, the pickling time is 15-20 minutes, and the pickling temperature is 60-65℃.

[0023] By adopting the above technical solution, oil, impurities, rust and oxides on the surface of the steel plate are removed, thereby ensuring the uniformity of the galvanized layer and making the galvanized layer stably adhere to the surface of the steel plate.

[0024] Preferably, the plating flux is composed of zinc chloride solution, ammonium chloride solution, sodium fluoride solution and barium chloride solution in a mass ratio of 1:1-3:0.15-0.25:0.1-0.2.

[0025] By adopting the above technical solution, not only can oxides and other impurities on the surface of the steel plate be reduced, but the dispersion uniformity and fluidity of liquid zinc can also be improved, promoting a more stable and uniform adhesion of liquid zinc on the surface of the steel plate, thereby improving the durability and quality of the coating. As a result, the galvanized steel plate can resist the corrosion of seawater and marine organisms when applied to marine vessels, thus extending the service life of components made of galvanized steel plate on marine vessels.

[0026] Preferably, the temperature of the zinc plating solution is 480-520℃.

[0027] By adopting the above technical solution, the diffusion rate of iron and zinc is ensured to be neither too fast nor too slow, thereby ensuring that the zinc coating thickness is uniform and the adhesion stability is high.

[0028] Preferably, the passivation solution for the passivation treatment is prepared by the following method:

[0029] Weigh out 10-20 parts by weight of waterborne acrylic resin, 5-10 parts by weight of chromium trioxide, 1-2 parts by weight of tartaric acid, 2-8 parts by weight of modified filler, 2-5 parts by weight of polyvinyl alcohol, 100-120 parts by weight of water, and 0.5-1 parts by weight of defoamer, and mix them evenly to obtain a passivation solution.

[0030] By adopting the above technical solution, the good water resistance of the water-based acrylic resin film is utilized to protect the galvanized steel sheet from corrosion. Combined with the filling effect of the modified filler, the mechanical strength and durability of the passivation film are improved. Furthermore, the combination of polyvinyl alcohol and water-based acrylic resin can further improve the adhesion stability of the passivation film on the surface of the galvanized steel sheet, thereby enabling components made from the finished galvanized steel sheet to have a longer service life in seawater.

[0031] Preferably, the modified filler is prepared by the following method:

[0032] Mesoporous silica was weighed and soaked and dispersed in vanilla solution. Then the mesoporous silica was separated and phenolic resin solution was uniformly sprayed on the surface. Then sodium borate and shellac solution were uniformly sprayed on the surface. After drying and dispersion, the modified filler was obtained.

[0033] By adopting the above technical solution, mesoporous silica, vanilla solution, phenolic resin solution, sodium borate, and shellac solution are combined. The adsorption effect of mesoporous silica is utilized to facilitate the adsorption of vanilla solution, so that vanilla is attached to the pore structure of mesoporous silica. Then, phenolic resin solution is used for coating treatment, followed by bonding with sodium borate, and finally sealing with shellac to obtain modified filler.

[0034] When components made from galvanized steel sheets are used on ships, they are inevitably subject to corrosion from marine organisms and scratches from other substances during ship operation. When the ship is subjected to scratches and impacts, shellac, phenolic resin, and mesoporous silica, with their high strength and toughness, can resist the impact and minimize scratches on the components, thus affecting the service life of the galvanized steel sheets on the ship.

[0035] Even if scratches appear on the surface of the galvanized steel sheet due to abrasion, the sodium borate trapped inside the shellac gradually dissolves and is released. Utilizing the solubility of sodium borate in water, the shellac can be slowly dissolved. The increased viscosity of the dissolved shellac can repair the scratches. Combined with the strength and corrosion resistance of phenolic resin, this extends the service life of this component on the ship.

[0036] Microorganisms in water easily metabolize and produce acid, which then adheres to the surface of galvanized steel plates. The alkalinity of sodium borate, combined with the fragrance of vanilla, can remove and repel microorganisms in lake and river water, thus further extending the service life of this component on ships. Furthermore, the odor dissipates more slowly after the phenolic resin and shellac solution form a film, which can prolong the effective duration of the vanilla fragrance.

[0037] Preferably, the phenolic resin solution is composed of phenolic resin melt, EVA melt, sodium borate and polyethylene glycol 1000 in a mass ratio of 1:0.2-0.5:0.1-0.2:0.5-1.

[0038] By adopting the above technical solution, the combination of phenolic resin melt and EVA melt can improve the adhesion of sodium borate to the surface of galvanized steel sheet, and balance the strength and toughness of the passivation layer, ensuring that the finished galvanized steel sheet has both high strength and high toughness, thereby extending the service life of galvanized steel sheet on ships.

[0039] In summary, this application has the following beneficial effects:

[0040] 1. By limiting the iron powder content on the steel plate surface, the galvanized layer is made smoother and more uniform, less prone to problems such as zinc particles and zinc scars. As the steel plate is galvanized, the zinc dross content in the galvanizing solution gradually increases. By adding porous zinc ingots, the zinc ingots are rapidly melted, and during the melting process, the porous zinc ingots gradually break into smaller pieces. These smaller pieces can be evenly dispersed, preventing localized low temperatures in the galvanizing solution. This ensures that the galvanized layer has a uniform thickness and good adhesion stability. Utilizing the good corrosion resistance and water resistance of the galvanized layer, in the continuous production process, each galvanized steel plate is guaranteed to have the advantages of a smooth surface, low roughness, good corrosion resistance, good wear resistance, good sealing integrity, and resistance to seawater penetration.

[0041] 2. When porous zinc ingots are added to the galvanizing bath, the high temperature of the galvanizing bath, combined with the thermal conductivity of silicon carbide fibers and the porosity of the porous zinc ingots, promotes rapid melting of the ingots. This minimizes the problem of localized temperature drops in the galvanizing bath caused by adding large zinc ingots, which could affect the thickness and uniformity of the galvanized layer. The gas volatilized from glycerol helps disperse the zinc ingots, and ammonium chloride, with its fluidity and dispersibility, further promotes the dispersion of zinc ingot particles, ensuring that the zinc ingots can make uniform contact with the steel plate while melting rapidly. Moreover, the hydrogen gas produced by the thermal decomposition of ammonium chloride promotes rapid and convenient deposition of zinc on the steel plate surface, increasing the zinc deposition rate and ensuring the uniformity of the galvanized layer. This results in a galvanized layer with a smooth surface, wear resistance, corrosion resistance, and seawater resistance.

[0042] 3. The combination of polyetheretherketone (PEEK), ethyl cellulose, and iron powder, under the high temperature of the galvanizing solution, allows PEEK and ethyl cellulose to gradually melt, improving the adhesion stability of the galvanized layer at the scratched location. Combined with the reaction of iron powder and zinc liquid, this enhances the galvanizing effect at the scratched location. Furthermore, the bonding effect of ethyl cellulose and PEEK further improves the adhesion stability of the galvanized layer on the scratched surface, thus giving the galvanized steel sheet high strength and good wear resistance and corrosion resistance.

[0043] 4. The combination of phenolic resin melt, EVA melt, and shellac solution provides good water resistance, salt resistance, and acid and alkali resistance, thereby improving the service life of galvanized steel sheets.

[0044] 5. Since silicon carbide fiber has a lower density than zinc liquid, it can be removed along with the scum. Detailed Implementation

[0045] The present application will be further described in detail below with reference to the embodiments.

[0046] Example of preparation of porous zinc ingots

[0047] Preparation Example 1: Porous zinc ingots were prepared by the following method:

[0048] Large zinc ingots are weighed and crushed to obtain zinc blocks with an average particle size of 1 cm. Then, 0.2 kg of glycerol is evenly sprayed onto the surface of 1 kg of zinc blocks, followed by 0.05 kg of ammonium chloride and 0.05 kg of silicon carbide fiber. The average length of the silicon carbide fiber is 5 mm. After being mixed evenly, the mixture is dried and dispersed to obtain the finished porous zinc ingot. The porous zinc ingot has an average length of 10 cm, an average width of 5 cm, and an average thickness of 3 cm.

[0049] Preparation example of ethyl cellulose composite liquid

[0050] Preparation Example 2: The ethyl cellulose composite liquid was prepared by the following method:

[0051] Weigh 1 kg of ethyl cellulose ethanol solution, 0.38 kg of iron powder, and 0.15 kg of polyether ether ketone microparticles, mix and stir evenly to prepare ethyl cellulose composite solution; the mass fraction of ethyl cellulose ethanol solution is 0.5%, the average particle size of iron powder is 100 nm, and the average particle size of polyether ether ketone microparticles is 40 nm.

[0052] Preparation Example 3: The ethyl cellulose composite liquid was prepared by the following method:

[0053] Weigh 1 kg of ethyl cellulose ethanol solution, 0.2 kg of iron powder, and 0.1 kg of polyether ether ketone microparticles, mix and stir evenly to obtain ethyl cellulose composite solution.

[0054] Preparation Example 4: The ethyl cellulose composite liquid was prepared by the following method:

[0055] Weigh 1 kg of ethyl cellulose ethanol solution, 0.5 kg of iron powder, and 0.2 kg of polyether ether ketone microparticles, mix and stir evenly to obtain ethyl cellulose composite solution.

[0056] Example of preparation of plating flux

[0057] Preparation Example 5: The flux was prepared by the following method:

[0058] Weigh 1 kg of zinc chloride solution, 2 kg of ammonium chloride solution, 0.2 kg of sodium fluoride solution and 0.15 kg of barium chloride solution, mix and stir evenly to prepare a flux; the zinc chloride solution is a 16% zinc chloride aqueous solution, the ammonium chloride solution is a 15% ammonium chloride aqueous solution, the sodium fluoride solution is a 2% sodium fluoride solution, and the barium chloride solution is a 1% barium chloride aqueous solution.

[0059] Preparation Example 6: The difference between this preparation example and Preparation Example 5 is that:

[0060] Take 1 kg of zinc chloride solution, 1 kg of ammonium chloride solution, 0.15 kg of sodium fluoride solution and 0.1 kg of barium chloride solution, mix and stir evenly to prepare a plating flux.

[0061] Preparation Example 7: The difference between this preparation example and Preparation Example 5 is that:

[0062] Take 1 kg of zinc chloride solution, 3 kg of ammonium chloride solution, 0.25 kg of sodium fluoride solution and 0.2 kg of barium chloride solution, mix them evenly to prepare a plating flux.

[0063] Preparation example of modified filler

[0064] Preparation Example 8: The modified filler was prepared by the following method:

[0065] Phenolic resin is heated to 120°C to soften and melt, thus obtaining a phenolic resin melt; EVA is heated to 100°C to soften and melt, thus obtaining an EVA melt.

[0066] Weigh 1 kg of phenolic resin melt, 0.4 kg of EVA melt, and 0.8 kg of polyethylene glycol 1000 and mix them evenly to obtain a mixed liquid. Add 0.16 kg of sodium borate at a rate of 60 g / min to the mixed liquid. The average particle size of sodium borate is 80 nm. Mix and stir evenly to obtain phenolic resin liquid.

[0067] 1 kg of mesoporous silica was weighed and soaked in 10 kg of vanilla solution. The average particle size of the mesoporous silica was 100 nm. The vanilla solution was a 10% vanilla aqueous solution. The silica was ultrasonically dispersed at 20 kHz for 30 min. Then the mesoporous silica was separated. 0.25 kg of phenolic resin solution was uniformly sprayed onto the surface. Then 0.1 kg of sodium borate and 0.65 kg of shellac solution were uniformly sprayed onto the surface. The average particle size of the sodium borate was 10 nm. The shellac solution was obtained by heating shellac to 120 °C and completely melting it. After drying and dispersion, the modified filler was obtained.

[0068] Preparation Example 9: The difference between this preparation example and Preparation Example 8 is that:

[0069] Weigh 1 kg of phenolic resin melt, 0.2 kg of EVA melt, and 0.5 kg of polyethylene glycol 1000, mix and stir evenly to obtain a mixed liquid. Add 0.1 kg of sodium borate at a rate of 60 g / min to the mixed liquid. The average particle size of sodium borate is 100 nm. Mix and stir evenly to obtain phenolic resin solution.

[0070] Preparation Example 10: The difference between this preparation example and Preparation Example 8 is that:

[0071] Weigh 1 kg of phenolic resin melt, 0.5 kg of EVA melt, and 1 kg of polyethylene glycol 1000, mix and stir evenly to obtain a mixed liquid. Add 0.2 kg of sodium borate at a rate of 60 g / min to the mixed liquid. The average particle size of sodium borate is 100 nm. Mix and stir evenly to obtain phenolic resin solution.

[0072] Example of passivation solution preparation

[0073] Preparation Example 11: The passivation solution was prepared by the following method:

[0074] Weigh 15 kg of waterborne acrylic resin, 8 kg of chromium trioxide, 1.5 kg of tartaric acid, 5 kg of the modified filler prepared in Preparation Example 8, 3 kg of polyvinyl alcohol, 110 kg of water, and 0.8 kg of defoamer, mix and stir evenly to obtain a passivation solution.

[0075] Preparation Example 12: The passivation solution was prepared by the following method:

[0076] Weigh 10 kg of waterborne acrylic resin, 5 kg of chromium trioxide, 1 kg of tartaric acid, 2 kg of the modified filler prepared in Preparation Example 9, 2 kg of polyvinyl alcohol, 100 kg of water, and 0.5 kg of defoamer, mix and stir evenly to obtain a passivation solution.

[0077] Preparation Example 13: The passivation solution was prepared by the following method:

[0078] Weigh 20 kg of waterborne acrylic resin, 10 kg of chromium trioxide, 2 kg of tartaric acid, 8 kg of the modified filler prepared in Preparation Example 10, 5 kg of polyvinyl alcohol, 120 kg of water, and 1 kg of defoamer, mix and stir evenly to obtain a passivation solution.

[0079] Example

[0080] Example 1: A continuous processing technology for hot-dip galvanized steel sheets for marine vessels:

[0081] S1. Several steel plates were sequentially washed twice with water, pickled, washed three times with water, and dried under nitrogen at 85°C for 10 minutes. During the pickling process, the pickling solution was a 60% hydrochloric acid solution with water as the solvent. The pickling time was 18 minutes, and the pickling temperature was 62°C. Then, the steel plates were immersed in a flux for 20 minutes and dried under nitrogen at 150°C. The flux was the flux prepared in Preparation Example 5, and a fluxed steel plate was obtained. The thickness of the steel plate was 0.8 mm.

[0082] S2. Several steel sheets to be galvanized are placed in the galvanizing solution in sequence for galvanizing treatment. Then, excess zinc liquid is scraped off the surface of the steel sheets to be galvanized. The excess zinc liquid is returned to the galvanizing solution. The galvanizing solution is made by heating metallic zinc to 520℃ for hot melting. After the previous steel sheet to be galvanized is completed, the next steel sheet to be galvanized is galvanized. As the number of galvanized steel sheets increases, porous zinc ingots prepared in Preparation 1 are added to the galvanizing solution to continue the galvanizing treatment of the subsequent steel sheets to be galvanized. The aluminum content is maintained at 0.15-0.17% throughout the galvanizing process. During the galvanizing process, dross is removed at any time. After the porous zinc ingots are added, the subsequent steel sheets to be galvanized are stopped from entering the galvanizing solution before the dross is removed, thus obtaining a semi-finished product.

[0083] S3. Several semi-finished products were sequentially cooled to 40°C by water quenching, and then placed in the passivation solution prepared in Preparation Example 11 for passivation treatment for 60 seconds. After drying, the finished galvanized steel sheet was obtained; the average thickness of the galvanized steel sheet was 1.2 mm.

[0084] Example 2: The difference between this example and Example 1 is that:

[0085] S1. Several steel plates were sequentially washed twice with water, pickled, washed three times with water, and dried under nitrogen at 85°C for 10 minutes. During the pickling process, the pickling solution was a 50% hydrochloric acid solution with water as the solvent. The pickling time was 20 minutes and the pickling temperature was 65°C. Then, the steel plates were immersed in a flux for 20 minutes and dried under nitrogen at 150°C. The flux was the flux prepared in Preparation Example 6, and a fluxed steel plate was obtained.

[0086] S2. The zinc plating solution is obtained by heating metallic zinc to 480℃ and then melting it.

[0087] S3. Several semi-finished products were sequentially cooled to 40°C by water quenching, and then placed in the passivation solution prepared in Preparation Example 12 for passivation treatment for 60 seconds. After drying, the finished galvanized steel sheet was obtained.

[0088] Example 3: The difference between this example and Example 1 is that:

[0089] S1. Several steel plates were sequentially washed twice with water, pickled, washed three times with water, and dried under nitrogen at 85°C for 10 minutes. During the pickling process, the pickling solution was a 65% hydrochloric acid solution with water as the solvent. The pickling time was 15 minutes and the pickling temperature was 60°C. Then, the steel plates were immersed in a flux for 20 minutes and dried under nitrogen at 150°C. The flux was the flux prepared in Preparation Example 7, and a fluxed steel plate was obtained.

[0090] S2. The zinc plating solution is obtained by heating metallic zinc to 520℃ and then melting it.

[0091] S3. Several semi-finished products were sequentially cooled to 40°C by water quenching, and then placed in the passivation solution prepared in Preparation Example 13 for passivation treatment for 60 seconds. After drying, the finished galvanized steel sheet was obtained.

[0092] Example 4: The difference between this example and Example 1 is that:

[0093] S1. Several steel plates were washed twice with water. After washing, the ethyl cellulose composite solution prepared in Preparation Example 2 was evenly coated on the scratches and grooves on the surface of the steel plates. The ethyl cellulose composite solution completely sealed the scratches. After drying and polishing, the surface of the steel plates was smooth and flat. Then, the plates were pickled, washed three times with water, and dried under nitrogen at 85°C for 10 minutes. During the pickling process, the pickling solution was a 60% hydrochloric acid solution with water as the solvent. The pickling time was 18 minutes and the pickling temperature was 62°C. Then, the steel plates were immersed in a flux for 20 minutes and dried under nitrogen at 150°C. The flux was the flux prepared in Preparation Example 5. A fluxed steel plate was obtained.

[0094] Example 5: The difference between this example and Example 4 is that:

[0095] The ethyl cellulose composite solution used was the ethyl cellulose composite solution prepared in Preparation Example 3.

[0096] Example 6: The difference between this example and Example 4 is that:

[0097] The ethyl cellulose composite solution used was the ethyl cellulose composite solution prepared in Preparation Example 4.

[0098] Example 7: The difference between this example and Example 1 is that:

[0099] No ammonium chloride or silicon carbide fiber was added to the porous zinc ingot.

[0100] Example 8: The difference between this example and Example 1 is that:

[0101] No vanilla solution was added during the preparation of the unmodified filler in the passivation solution.

[0102] Example 9: The difference between this example and Example 1 is that:

[0103] Sodium borate and shellac solution were not added during the preparation of the passivation solution modified filler.

[0104] Example 10: The difference between this example and Example 4 is that:

[0105] No iron powder or polyether ether ketone microparticles were added during the preparation of the ethyl cellulose composite liquid.

[0106] Comparative Example

[0107] Comparative Example 1: The difference between this comparative example and Example 1 is that:

[0108] In the raw materials, porous zinc ingots are replaced with large zinc ingots of the same weight. The large zinc ingots have an average length of 10cm, an average width of 5cm, and an average thickness of 3cm.

[0109] Performance testing

[0110] 1. Flatness and uniformity inspection

[0111] The preparation methods of Examples 1-9 and Comparative Example 1 were used to prepare finished galvanized steel sheets. The surface roughness of the galvanized steel sheets was tested according to GB / T2518-2019, and the data were recorded.

[0112] Furthermore, the surface quality was rated and scored: 10 points for no pits, zinc slag, black spots, or white spots → 1 point for a large number of pits, zinc slag, black spots, or white spots that account for more than 80% of the total area. Data from Examples 1-7 and Comparative Example 1 were recorded.

[0113] 2. Strength testing

[0114] Finished galvanized steel sheets were prepared using the preparation methods of Examples 1-10 and Comparative Example 1, respectively. The raw material sample steel sheet had three scratches on its surface, with a length of about 1 cm and a depth of about 0.1-0.2 mm. The tensile strength of the galvanized steel sheet was tested according to GB / T2518-2019 (denoted as Group A tensile strength). The average value of 50 groups of galvanized steel sheets was taken and the data was recorded.

[0115] 3. Corrosion resistance testing

[0116] The preparation methods of Examples 1-3, 7-9 and Comparative Example 1 were used to prepare finished galvanized steel sheets. The 20cm×20cm galvanized steel sheet samples were completely immersed in 100kg of seawater. After immersion for 30 days, the tensile strength was tested again (referred to as the tensile strength of Group B), and the data were recorded.

[0117] Corrosion resistance was tested according to GB / T10125-1997, and the data of Examples 1-6 were recorded as the percentage of the corroded area to the total area after 72 hours.

[0118] 4. Marine life detection

[0119] Finished galvanized steel sheets were prepared using the preparation methods described in Examples 1-3 and 8-9, respectively. A 20cm × 20cm sample of galvanized steel sheet was placed in 100kg of river water containing 100 barnacles. After immersion for 30 days, the amount of barnacles adhering to the surface of the galvanized steel sheet was recorded. Then, friction scratches were created on the surface of the galvanized steel sheet, with a thickness approximately 1 / 5 of the galvanized layer thickness (to simulate scratches caused by friction on a ship in port or other conditions, or scratches caused after the barnacles were removed). The sheet was then placed again in a new 100kg of river water containing 100 barnacles. After immersion for 30 days, the amount of barnacles adhering to the surface of the galvanized steel sheet (total days 60 days) and the tensile strength of the galvanized steel sheet after the barnacles were removed (referred to as group C tensile strength) were recorded.

[0120] 5. Adhesion test

[0121] Finished galvanized steel sheets were prepared using the methods described in Examples 1-7 and Comparative Example 1, respectively. Following GB / T9286-1998, a grid pattern of approximately 1 mm was drawn on the paint film surface using a utility knife. 2 The adhesion was peeled off with 3M tape, reaching the surface of the zinc layer. The test results were graded as follows: 0-5% peeling area was grade 1, 5%-10% (excluding 10%) was grade 2, 10%-30% (excluding 30%) was grade 3, 30-60% (excluding 60%) was grade 4, and 60%-100% was grade 5.

[0122] The 200th to 250th galvanized steel sheet samples prepared using the above process were selected as test samples.

[0123] Table 1 Performance Test Table (where " / " indicates that this item was not tested in this embodiment or comparative example, so there is no data)

[0124]

[0125] As can be seen from Examples 1-3 and Table 1, the galvanized steel sheet prepared in this application has good flatness and is not prone to pits, scratches and spots on the surface. It also has good corrosion resistance, high mechanical strength and seawater corrosion resistance. The finished galvanized steel sheet has the advantages of flat surface, low roughness, corrosion resistance, good wear resistance, good sealing integrity, not easy to penetrate seawater and good adhesion stability.

[0126] As can be seen from Examples 1 and 4-6 and Table 1, the treatment of scratches with ethyl cellulose composite liquid improves the mechanical strength of steel plates and the surface smoothness of galvanized steel plates.

[0127] Combining Examples 1 and 7-9 with Table 1, it can be seen that in Example 7, no ammonium chloride and silicon carbide fiber were added to the porous zinc ingot. Compared with Example 1, the roughness of the hot-dip galvanized steel sheet prepared in Example 7 was greater than that in Example 1, the fraction was lower than that in Example 1, and the tensile strength was lower than that in Example 1. This indicates that the combination of sodium chloride and silicon carbide fiber can promote the rapid dispersion and hot melting of zinc ingot, and is less likely to cause the problem of local low temperature, thereby ensuring the flatness and smoothness of the zinc layer in hot-dip galvanization, and can also improve tensile strength and adhesion stability.

[0128] In Example 8, no vanilla solution was added during the preparation of the unmodified filler in the passivation solution. Compared with Example 1, the tensile strength of the hot-dip galvanized steel sheet prepared in Example 8 was lower than that in Example 1. Barnacles and other organisms easily adhered to the surface of the galvanized steel sheet, and the difference between the initial strength of the galvanized steel sheet and the tensile strength of the galvanized steel sheet after treatment with seawater and marine organisms was greater than the corresponding difference in Example 1. This indicates that vanilla has the effect of repelling marine organisms, thereby minimizing the adhesion of marine organisms to the surface of the galvanized steel sheet and affecting its service life.

[0129] In Example 9, no sodium borate or shellac was added during the preparation of the passivation solution modified filler. Compared to Example 1, the tensile strength of the hot-dip galvanized steel sheet prepared in Example 9 was lower than that in Example 1. Barnacles and other organisms easily adhered to the surface of the galvanized steel sheet, and the difference between the initial strength of the galvanized steel sheet and the tensile strength of the galvanized steel sheet after treatment with seawater and marine organisms was greater than the corresponding difference in Example 1. This indicates that the combination of sodium borate and shellac can increase the mechanical strength of the galvanized steel sheet, and the galvanized steel sheet can self-repair after being scratched, thus ensuring the mechanical strength and service life of the galvanized steel sheet.

[0130] Combining Examples 4 and 10 with Table 1, it can be seen that in the preparation process of the ethyl cellulose composite liquid in Example 10, no iron powder and polyether ether ketone microparticles were added. Compared with Example 4, the tensile strength of the galvanized steel sheet prepared in Example 10 was lower than that in Example 4. This indicates that the addition of iron powder and polyether ether ketone microparticles can improve the adhesion stability of the zinc layer and improve the mechanical strength of the finished galvanized steel sheet.

[0131] Combining Example 1 and Comparative Example 1 with Table 1, it can be seen that in Comparative Example 1, when large zinc ingots of the same mass were replaced with porous zinc ingots, the galvanized steel sheet prepared in Comparative Example 1 had a higher roughness and a lower zinc plating fraction than that in Example 1, and the tensile strength was also lower than that in Example 1. This indicates that adding large zinc ingots to the galvanizing solution can easily cause a problem layer due to sudden local temperature changes, which can easily affect the uniformity, flatness, and adhesion stability of the coating on the steel sheet surface.

[0132] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A continuous processing technology for hot-dip galvanized steel sheets for marine vessels, characterized in that, Includes the following steps: S1. Several steel plates are sequentially subjected to pretreatment, pickling, water washing, and flux treatment to obtain fluxed steel plates; S2. Several steel sheets are placed in the zinc plating solution for zinc plating in sequence. As the number of steel sheets to be zinc plating increases, porous zinc ingots are added to the zinc plating solution to continue zinc plating. During the zinc plating process, the aluminum content is maintained at 0.15-0.17% to obtain a semi-finished product. S3. Several semi-finished products are successively cooled, passivated and dried to obtain galvanized steel sheets; The porous zinc ingot is prepared by the following method: Large zinc ingots are broken into zinc blocks, then glycerol is sprayed evenly, followed by ammonium chloride and silicon carbide fiber. The mixture is stirred evenly, dried, and dispersed to obtain the finished porous zinc ingot.

2. The continuous processing technology for hot-dip galvanized steel sheets for marine vessels according to claim 1, characterized in that, The specific steps of the preprocessing are as follows: After washing, ethyl cellulose composite liquid is applied to the scratches and grooves on the steel plate surface, and then dried and polished until the steel plate surface is smooth and flat.

3. The continuous processing technology for hot-dip galvanized steel sheets for marine vessels according to claim 2, characterized in that, The ethyl cellulose composite solution is composed of an ethyl cellulose ethanol solution, iron powder, and polyetheretherketone microparticles in a mass ratio of 1:0.2-0.5:0.1-0.

2.

4. The continuous processing technology for hot-dip galvanized steel sheets for marine vessels according to claim 1, characterized in that, The pickling process uses a 50-65% hydrochloric acid solution, with a pickling time of 15-20 minutes and a pickling temperature of 60-65℃.

5. The continuous processing technology for hot-dip galvanized steel sheets for marine vessels according to claim 1, characterized in that, The plating flux is composed of zinc chloride solution, ammonium chloride solution, sodium fluoride solution and barium chloride solution in a mass ratio of 1:1-3:0.15-0.25:0.1-0.

2.

6. The continuous processing technology for hot-dip galvanized steel sheets for marine vessels according to claim 1, characterized in that, The temperature of the zinc plating solution is 480-520℃.

7. The continuous processing technology for hot-dip galvanized steel sheets for marine vessels according to claim 1, characterized in that, The passivation solution used in the passivation treatment was prepared using the following method: Weigh out 10-20 parts by weight of waterborne acrylic resin, 5-10 parts by weight of chromium trioxide, 1-2 parts by weight of tartaric acid, 2-8 parts by weight of modified filler, 2-5 parts by weight of polyvinyl alcohol, 100-120 parts by weight of water, and 0.5-1 parts by weight of defoamer, and mix them evenly to obtain a passivation solution.

8. The continuous processing technology for hot-dip galvanized steel sheets for marine vessels according to claim 7, characterized in that, The modified filler was prepared by the following method: Mesoporous silica was weighed and soaked and dispersed in vanilla solution. Then the mesoporous silica was separated and phenolic resin solution was uniformly sprayed on the surface. Then sodium borate and shellac solution were uniformly sprayed on the surface. After drying and dispersion, the modified filler was obtained.

9. The continuous processing technology for hot-dip galvanized steel sheets for marine vessels according to claim 8, characterized in that, The phenolic resin solution is composed of molten phenolic resin, molten EVA, sodium borate, and polyethylene glycol 1000 in a mass ratio of 1:0.2-0.5:0.1-0.2:0.5-1.

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