A processing technology of anti-corrosion galvanized sheet

Abstract

The application relates to the technical field of hot galvanization, and particularly discloses a processing technology of an anti-corrosion galvanized sheet. The processing technology of the anti-corrosion galvanized sheet comprises the following steps: degreasing; pickling; plating assisting: immersing the pickled base material into an ammonium-free plating assisting liquid, the plating assisting temperature is 40-60 DEG C, the plating assisting time is 1-3 min, wherein the ammonium-free plating assisting liquid comprises 80-100 g / L of zinc chloride, 30-50 g / L of sodium chloride, 8-10 g / L of potassium chloride and 1-1.2 g / L of iron-removing adsorbent; hot plating; passivation. The preparation method has the advantages that the protection time of the galvanized layer is prolonged.

Description

Technical Field

[0001] This application relates to the field of hot-dip galvanizing technology, and more specifically, to a processing technology for corrosion-resistant galvanized sheets. Background Technology

[0002] Electroplating zinc is a process that electrolyzes a zinc salt solution to form a metallic zinc deposit on the surface of a steel substrate. Hot zinc plating, on the other hand, involves immersing the steel substrate in molten zinc, allowing the zinc to react with the iron on the surface of the steel substrate to form a zinc plating layer. This zinc plating layer protects the steel substrate and reduces corrosion.

[0003] After prolonged use, the galvanized layer on the surface of steel substrates is prone to peeling off. Peeled or broken galvanized layers can easily trap moisture, losing their protective function for the steel substrate. Corrosive substances in the air can penetrate the galvanized layer and come into contact with the steel substrate, increasing the corrosion of both the galvanized layer and the substrate, thus reducing the service life of the substrate. Summary of the Invention

[0004] To extend the protective time of the galvanized layer, this application provides a processing technology for corrosion-resistant galvanized steel sheets, employing the following technical solution: A processing technology for corrosion-resistant galvanized steel sheet includes the following steps: Degreasing: Immerse the substrate in a degreasing agent for degreasing and oil removal treatment for 25-40 minutes; Pickling: Immerse the degreased substrate in hydrochloric acid solution for pickling. The concentration of hydrochloric acid solution is 5-20wt%, and the pickling time is 5-10min. After pickling, rinse with clean water for 1-2min. Fluxing: Immerse the pickled substrate in an ammonium-free fluxing solution at a temperature of 40-60℃ for 1-3 minutes. The ammonium-free fluxing solution includes 80-100 g / L zinc chloride, 30-50 g / L sodium chloride, 8-10 g / L potassium chloride, and 1-1.2 g / L iron removal adsorbent. Hot-dip galvanizing: The substrate after fluxing is immersed in molten zinc at a temperature of 450-520℃ for 4-8 minutes. Passivation: Immerse the hot-dip galvanized and cooled substrate in the passivation solution for 2-3 minutes, and rinse with clean water 2-5 times.

[0005] By adopting the above technical solutions, degreasing can remove grease from the surface of the substrate, making the substrate surface clean and free from grease interference between the substrate and the zinc plating layer. Pickling solution can thoroughly clean the rust on the surface of the substrate, thereby improving the uniformity and adhesion of the zinc plating layer. Fluxing solution can form a thin film on the surface of the substrate, which can activate the surface of the substrate and enhance the adhesion between the substrate and the zinc plating layer, thereby extending the protective effect and time of the zinc plating layer on the substrate. Iron removal adsorbent can effectively reduce the iron content in the ammonium-free fluxing solution, thereby reducing zinc dross in the zinc bath and improving the fluxing effect.

[0006] Preferably, the ammonium-free plating solution further includes 3.5-8.1 g / L of nickel chloride.

[0007] By adopting the above technical solution, it is found that an excessively thick zinc plating layer can affect the adhesion of the zinc plating layer. Adding nickel chloride to the ammonium-free flux can reduce the thickness of the formed zinc plating layer, thereby improving the adhesion of the zinc plating layer. The concentration of nickel chloride is controlled at 3.5-8.1 g / L, which can effectively reduce the thickness of the zinc plating layer.

[0008] Preferably, the ammonium-free flux further includes a surfactant, which is prepared by compounding sodium dodecyl sulfate and sodium lauramide glycidate, with a molar ratio of sodium dodecyl sulfate to sodium lauramide glycidate of 1:(0.42-1.51), and the concentration of sodium dodecyl sulfate in the ammonium-free flux is 0.068-0.12 g / L.

[0009] By adopting the above technical solution, the surfactant formed by the compounding of sodium dodecyl sulfate and sodium lauramide glycidate can reduce the surface tension of the fluxing solution and improve the wettability between the fluxing solution and the substrate. At the same time, it works synergistically with the metal salt in the fluxing solution to make the salt film formed by the fluxing solution more uniform and dense, thereby improving the coating of the fluxing solution on the substrate.

[0010] Preferably, the iron removal adsorbent comprises the following raw materials: liquid A and liquid B in a volume ratio of (9-11):1, liquid A comprising myricetin and water, wherein the amount of myricetin added is 3-6 wt% of water; liquid B comprises glutaraldehyde.

[0011] By adopting the above technical solution, after the tannin of bayberry is mixed with glutaraldehyde and cross-linked and cured, it can adsorb ferrous and ferric ions in the ammonium-free flux. If the content of ferric and ferrous ions in the ammonium-free flux is too high, it will easily increase the zinc dross in the zinc bath and affect the coating quality. The iron adsorbent formed by the cured bayberry tannin has a good adsorption effect on iron in the ammonium-free flux, which can reduce the iron content in the ammonium-free flux and thus improve the fluxing effect.

[0012] Preferably, the liquid A further includes aminated silica, and the mass ratio of aminated silica to bayberry tannin is 1:(0.4-0.6).

[0013] By adopting the above technical solution, when solution A and solution B are mixed, bayberry tannin can be grafted onto aminated silica under the action of glutaraldehyde. The resulting iron removal adsorbent has better water resistance, longer service life, and better adsorption effect on iron and ferrous ions in ammonium-free plating solution.

[0014] Preferably, the preparation method of the iron removal adsorbent includes the following steps: adding aminated silica and myricetin to water, stirring for 10-12 hours to obtain solution A, adding solution B to solution A, crosslinking at 30-40°C for 22-24 hours, filtering, washing, and vacuum drying at 35-40°C for 23-24 hours to obtain the iron removal adsorbent.

[0015] By adopting the above technical solution, aminated silica and bayberry tannin are thoroughly mixed after stirring. After the mixture of solution A and solution B, the aminated silica and bayberry tannin crosslink under the action of glutaraldehyde and solidify to form an iron removal adsorbent. The bayberry tannin is located on the surface of silica. The two work together to adsorb iron in the ammonium-free flux, thereby ensuring that the content of iron ions and ferrous ions in the ammonium-free flux is low and ensuring the fluxing effect of the flux.

[0016] Preferably, the pH of the ammonium-free plating solution is 3.8-4.3.

[0017] By adopting the above technical solution, the pH of the ammonium-free flux is adjusted to 3.8-4.3. Within this pH range, the adsorption rate and effect of the iron removal adsorbent on ferric and ferrous ions are optimal, and the surfactant activity is better, resulting in a better effect on reducing the surface tension of the ammonium-free flux. This is beneficial to improving the fluxing and coating effects of the flux on the substrate.

[0018] Preferably, the hydrochloric acid solution is circulated through the adsorption column at a flow rate of 50-55 mL / h. The adsorption column comprises the following raw materials: ion exchange resin and chelating agent, wherein the amount of chelating agent added is 0.4-0.6 wt% of the ion exchange resin.

[0019] By adopting the above technical solution, the chelating agent can complex with ferrous ions in hydrochloric acid solution to form a complex, and the ion exchange resin can replace the ions in hydrochloric acid solution, thereby reducing the concentration of ferrous ions in hydrochloric acid solution, thus reducing the ferrous content brought into the plating solution by the substrate and improving the plating effect.

[0020] In summary, this application has the following beneficial effects: 1. In this application, nickel chloride is added to the ammonium-free flux. Nickel chloride can effectively reduce the thickness of the zinc plating layer, thereby improving the adhesion of the zinc plating layer and extending the service life of the zinc plating layer. 2. The surfactant used in this application, which is a compound of sodium dodecyl sulfate and sodium lauramide glycidate, effectively reduces the surface tension of the flux and improves the wettability between the flux and the substrate. At the same time, it works synergistically with the metal salt in the flux to improve the coating properties of the flux on the substrate. 3. This application uses an iron removal adsorbent formed by the solidification of bayberry tannin. The iron removal adsorbent can adsorb iron ions and ferrous ions in the ammonium-free flux, reduce the iron content in the ammonium-free flux, thereby reducing the zinc dross content in the zinc bath and improving the fluxing effect and the coating effect of the zinc layer. Detailed Implementation

[0021] The present application will be further described in detail below with reference to the embodiments.

[0022] Preparation Examples of Iron Removal Adsorbents 1-4 Preparation Example 1 The iron removal adsorbent includes the following raw materials: liquid A and liquid B with a volume ratio of 9:1. Liquid A includes bayberry tannin and water, and the amount of bayberry tannin added is 6 wt% of water. Liquid B includes glutaraldehyde. The preparation method of the above-mentioned iron removal adsorbent includes the following steps: adding bayberry tannin to water, stirring for 10 hours to obtain solution A, adding solution B to solution A, crosslinking at 30°C for 24 hours, filtering, washing, and vacuum drying at 35°C for 23 hours to obtain the iron removal adsorbent.

[0023] Preparation Example 2 The iron removal adsorbent includes the following raw materials: liquid A and liquid B with a volume ratio of 11:1. Liquid A includes bayberry tannin and water, and the amount of bayberry tannin added is 3 wt% of water. Liquid B includes glutaraldehyde. The preparation method of the above-mentioned iron removal adsorbent includes the following steps: adding bayberry tannin to water, stirring for 12 hours to obtain solution A, adding solution B to solution A, crosslinking at 40°C for 22 hours, filtering, washing, and vacuum drying at 40°C for 24 hours to obtain the iron removal adsorbent.

[0024] Preparation Example 3 The iron removal adsorbent includes the following raw materials: solution A and solution B with a volume ratio of 9:1. Solution A includes bayberry tannin, water and aminated silica. The amount of bayberry tannin added is 6 wt% of water, and the mass ratio of aminated silica to bayberry tannin is 1:0.4.

[0025] The preparation method of the above-mentioned iron removal adsorbent includes the following steps: adding aminated silica and myricetin to water, stirring for 10 hours to obtain solution A, adding solution B to solution A, crosslinking at 30°C for 24 hours, filtering, washing, and vacuum drying at 35°C for 23 hours to obtain the iron removal adsorbent.

[0026] Preparation Example 4 The iron removal adsorbent includes the following raw materials: solution A and solution B with a volume ratio of 11:1. Solution A includes bayberry tannin, water and aminated silica. The amount of bayberry tannin added is 3 wt% of water, and the mass ratio of aminated silica to bayberry tannin is 1:0.6.

[0027] The preparation method of the above-mentioned iron removal adsorbent includes the following steps: adding aminated silica and myricetin to water, stirring for 12 hours to obtain solution A, adding solution B to solution A, crosslinking at 40°C for 22 hours, filtering, washing, and vacuum drying at 40°C for 24 hours to obtain the iron removal adsorbent.

[0028] Preparation of Ammonium-Free Plating Solution Example 5-19 Preparation Example 5 The ammonium-free plating solution includes 80 g / L of zinc chloride, 30 g / L of sodium chloride, 8 g / L of potassium chloride, and 1 g / L of iron removal adsorbent. The iron removal adsorbent is the one prepared in Preparation Example 1.

[0029] Preparation Example 6 The ammonium-free plating solution includes 100 g / L of zinc chloride, 50 g / L of sodium chloride, 10 g / L of potassium chloride, and 1 g / L of iron removal adsorbent. The iron removal adsorbent is the one prepared in Preparation Example 2.

[0030] Preparation Example 7 The difference between Preparation Example 7 and Preparation Example 5 is that the ammonium-free flux also includes 3.5 g / L of nickel chloride.

[0031] Preparation Example 8 The difference between Preparation Example 8 and Preparation Example 5 is that the ammonium-free flux also includes 8.1 g / L of nickel chloride.

[0032] Preparation Example 9 The difference between Preparation Example 9 and Preparation Example 5 is that the ammonium-free flux also includes 1 g / L of nickel chloride.

[0033] Preparation Example 10 The difference between Preparation Example 10 and Preparation Example 5 is that the ammonium-free flux also includes 10 g / L of nickel chloride.

[0034] Preparation Example 11 The difference between Preparation Example 11 and Preparation Example 7 is that the ammonium-free flux also includes a surfactant, which is a compound of sodium dodecyl sulfate and sodium lauramide glycidate, with a molar ratio of sodium dodecyl sulfate to sodium lauramide glycidate of 1:0.42, and the concentration of sodium dodecyl sulfate in the ammonium-free flux is 0.068 g / L.

[0035] Preparation Example 12 The difference between Preparation Example 12 and Preparation Example 7 is that the ammonium-free flux also includes a surfactant, which is a compound of sodium dodecyl sulfate and sodium lauramide glycidate, with a molar ratio of sodium dodecyl sulfate to sodium lauramide glycidate of 1:1.51, and the concentration of sodium dodecyl sulfate in the ammonium-free flux is 0.12 g / L.

[0036] Preparation Example 13 The difference between Preparation Example 13 and Preparation Example 11 is that the molar ratio of sodium dodecyl sulfate to sodium lauramide glycidate is 1:0.1.

[0037] Preparation Example 14 The difference between Preparation Example 14 and Preparation Example 11 is that the molar ratio of sodium dodecyl sulfate to sodium lauramide glycidate is 1:2.

[0038] Preparation Example 15 The difference between Preparation Example 15 and Preparation Example 5 is that the ammonium-free plating solution also includes an iron removal adsorbent, which is the iron removal adsorbent obtained in Preparation Example 3.

[0039] Preparation Example 16 The difference between Preparation Example 16 and Preparation Example 5 is that the ammonium-free plating solution also includes an iron removal adsorbent, which is the iron removal adsorbent obtained in Preparation Example 4.

[0040] Preparation Example 17 The difference between Preparation Example 17 and Preparation Example 5 is that no iron removal adsorbent is added to the ammonium-free plating solution.

[0041] Preparation Example 18 The difference between Preparation Example 18 and Preparation Example 5 is that the content of iron removal adsorbent in the ammonium-free plating solution is 0.1 g / L.

[0042] Preparation Example 19 The difference between Preparation Example 19 and Preparation Example 5 is that the content of iron removal adsorbent in the ammonium-free plating solution is 2 g / L. Example

[0043] Example 1 A processing technology for corrosion-resistant galvanized steel sheet includes the following steps: Degreasing: The substrate is immersed in a degreasing agent for degreasing and oil removal for 25 minutes. The degreasing agent used is metal cleaning agent from Dongguan Hill Metal Materials Co., Ltd. Pickling: Immerse the degreased substrate in hydrochloric acid solution with a concentration of 5 wt% for pickling for 10 minutes. After pickling, rinse with clean water for 1 minute. Flushing: The pickled substrate is immersed in an ammonium-free flux solution at a flux temperature of 40°C for 1 minute. The ammonium-free flux solution is the one prepared in Preparation Example 5. Hot-dip galvanizing: The substrate after fluxing is immersed in molten zinc at a temperature of 450°C for 8 minutes. Passivation: The hot-dip galvanized substrate, cooled to room temperature, is immersed in the passivation solution for 2 minutes and rinsed twice with clean water. The passivation solution used is chromium-free passivation solution from Shenzhen Lijie Chemical Technology Co., Ltd., model 511.

[0044] Example 2 A processing technology for corrosion-resistant galvanized steel sheet includes the following steps: Degreasing: The substrate is immersed in a degreasing agent for degreasing and oil removal. The degreasing time is 40 minutes. The degreasing agent used is metal cleaning agent from Dongguan Hill Metal Materials Co., Ltd. Pickling: Immerse the degreased substrate in hydrochloric acid solution with a concentration of 20 wt% for pickling. The pickling time is 5 min. After pickling, rinse with clean water for 2 min. Flushing: The pickled substrate is immersed in an ammonium-free flux solution at a flux temperature of 60°C for 3 minutes. The ammonium-free flux solution is the one prepared in Preparation Example 6. Hot-dip galvanizing: The substrate after fluxing is immersed in molten zinc at a temperature of 450°C for 4 minutes. Passivation: The hot-dip galvanized substrate, cooled to room temperature, is immersed in the passivation solution for 3 minutes and rinsed with clean water 5 times. The passivation solution used is chromium-free passivation solution from Shenzhen Lijie Chemical Technology Co., Ltd., model 511.

[0045] Example 3 The difference between Example 3 and Example 1 is that the ammonium-free flux was prepared in Example 7.

[0046] Example 4 The difference between Example 4 and Example 1 is that the ammonium-free flux was prepared in Example 8.

[0047] Example 5 The difference between Example 5 and Example 1 is that the ammonium-free flux was prepared in Example 9.

[0048] Example 6 The difference between Example 6 and Example 1 is that the ammonium-free flux was prepared in Example 10.

[0049] Example 7 The difference between Example 7 and Example 1 is that the ammonium-free flux was prepared using the ammonium-free flux obtained in Preparation Example 11.

[0050] Example 8 The difference between Example 8 and Example 1 is that the ammonium-free flux was prepared in Example 12.

[0051] Example 9 The difference between Example 9 and Example 1 is that the ammonium-free flux was prepared in Example 13.

[0052] Example 10 The difference between Example 10 and Example 1 is that the ammonium-free flux used is the ammonium-free flux prepared in Preparation Example 14.

[0053] Example 11 The difference between Example 11 and Example 1 is that the ammonium-free flux used is the ammonium-free flux prepared in Preparation Example 15.

[0054] Example 12 The difference between Example 12 and Example 1 is that the ammonium-free flux used is the ammonium-free flux prepared in Preparation Example 16.

[0055] Example 13 The difference between Example 13 and Example 1 is that the hydrochloric acid solution is circulated through the adsorption column at a flow rate of 50 mL / h. The adsorption column includes the following raw materials: ion exchange resin and chelating agent, and the amount of chelating agent added is 0.4 wt% of the ion exchange resin.

[0056] Example 14 The difference between Example 14 and Example 1 is that the hydrochloric acid solution is circulated through the adsorption column at a flow rate of 55 mL / h. The adsorption column includes the following raw materials: ion exchange resin and chelating agent, and the amount of chelating agent added is 0.6 wt% of the ion exchange resin.

[0057] Comparative Example Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that the ammonium-free flux used was the ammonium-free flux prepared in Preparation Example 17.

[0058] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the ammonium-free flux used is the ammonium-free flux prepared in Preparation Example 18.

[0059] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the ammonium-free flux used was the ammonium-free flux prepared in Preparation Example 19.

[0060] Detection methods The steel sheets were hot-dip galvanized using the processes of Examples 1-14 and Comparative Examples 1-3. The resulting hot-dip galvanized steel sheets were then subjected to a neutral salt spray test, following the experimental method specified in GB / 6458-86 "Standard for Neutral Salt Spray Test of Metallic Coatings". The corrosion of the coating on the steel sheet surface was observed, and the corrosion rate was recorded in Table 1. Corrosion rate = (Area of ​​corroded area / Area of ​​coating) × 100% Compared to Comparative Example 1, Examples 1-2, which included an iron-removing adsorbent in the ammonium-free flux, showed a significant reduction in rust rate. This indicates that the iron-removing adsorbent effectively improves the fluxing effect of the ammonium-free flux, thereby enhancing the uniformity and density of the zinc coating and resulting in excellent salt spray resistance. The iron-removing adsorbent exhibits excellent adsorption properties for ferric and ferrous ions in the ammonium-free flux, reducing the iron content and consequently decreasing the ferric and ferrous ion content in the resulting film. When the film enters the zinc pot with the steel sheet, it reduces the amount of ferric and ferrous ions carried into the pot, thus reducing zinc dross and improving the fluxing effect. This, in turn, enhances the smoothness of the zinc coating, resulting in good uniformity and density, and improving the salt spray resistance of the galvanized steel sheet.

[0061] Compared with Example 1, Examples 3-4 added nickel chloride to the ammonium-free flux. Compared with Example 1, the corrosion rate of the zinc plating layer in Examples 3-4 was further reduced, indicating that the addition of nickel chloride to the ammonium-free flux can further improve the fluxing effect of the ammonium-free flux. The addition of nickel chloride can effectively reduce the thickness of the zinc plating layer and effectively improve the adhesion between the zinc plating layer and the substrate, thereby improving the adhesion between the zinc plating layer and the substrate, as well as the uniformity of the zinc plating layer, thus effectively improving the salt spray resistance of the galvanized steel sheet.

[0062] Compared with Example 3, the nickel chloride content in the ammonium-free fluxing solution changed in Examples 5-6. Compared with Example 1, the corrosion rate of the zinc plating layer decreased in Examples 5-6, but increased compared with Example 3. This indicates that both excessive and insufficient addition of nickel chloride will affect the fluxing effect of the ammonium-free fluxing solution. Insufficient addition of nickel chloride can easily lead to an excessively thick zinc layer, reducing its uniformity and adhesion, thereby reducing the salt spray resistance of the zinc plating layer. Excessive addition of nickel chloride will not reduce the thickness of the zinc plating layer, and the excess nickel chloride will be wasted.

[0063] Compared with Example 1, Examples 7-8 also added surfactants to the ammonium-free plating solution. Compared with Example 1, the corrosion rate of the zinc plating layer decreased in Examples 7-8, indicating that adding surfactants is beneficial to improving the plating effect of the ammonium-free plating solution. The surfactant formed by the compounding of sodium dodecyl sulfate and sodium laurylamide glycidate can effectively reduce the surface tension of the ammonium-free plating solution and improve the wettability between the ammonium-free plating solution and the steel plate. At the same time, the surfactant formed by the compounding works synergistically with the metal salts in the ammonium-free plating solution to make the salt film formed by the ammonium-free plating solution more uniform and dense, further improving the coating effect of the ammonium-free plating solution on the steel plate, thereby improving the plating effect of the ammonium-free plating solution and improving the uniformity and density of the zinc plating layer.

[0064] Compared with Example 7, the molar ratio of sodium dodecyl sulfate to sodium lauramide glycidate in the surfactant changed in Examples 9-10. Compared with Example 7, the corrosion rate of the zinc plating layer decreased in Examples 9-10, indicating that the molar ratio of sodium dodecyl sulfate to sodium lauramide glycidate affects the effect of the surfactant. A suitable molar ratio can effectively improve the activity of the surfactant formed by the compound and reduce the surface tension of the ammonium-free flux.

[0065] Compared with Example 7, in Examples 11-12, aminated silica was added during the preparation of the iron removal adsorbent. Compared with Example 7, the corrosion rate of the zinc plating layer in Examples 11-12 was further reduced, indicating that the addition of aminated silica is beneficial to improving the plating effect of the ammonium-free flux. Myrica tannin was grafted onto aminated silica under the action of glutaraldehyde. Aminated silica improved the water resistance of myrica tannin, making it less likely to decompose and dissolve in water. The iron removal adsorbent has a longer service life and a better adsorption effect on iron and ferrous ions in the ammonium-free flux.

[0066] Compared with Example 1, in Examples 13-14, the hydrochloric acid solution was circulated through the adsorption column. The corrosion rate of the galvanized layer decreased in Examples 13-14, indicating that the circulated hydrochloric acid solution through the adsorption column improves the pickling effect of the hydrochloric acid solution on the steel plate, increases the cleanliness of the steel plate surface, and thus improves the adhesion of the galvanized layer. The chelating agent in the adsorption column can complex with the ferrous ions in the hydrochloric acid solution, and the ion exchange resin can replace the ferrous ions in the hydrochloric acid solution, thereby reducing the concentration of ferrous ions in the hydrochloric acid solution, improving the cleaning effect of the hydrochloric acid solution on the steel plate, and thus improving the bonding effect between the galvanized layer and the steel plate, and improving the uniformity and adhesion of the galvanized layer.

[0067] Compared with Example 1, Comparative Example 2 reduced the amount of iron removal adsorbent added. Compared with Example 1, the corrosion rate of Comparative Example 2 increased, indicating that if the amount of iron removal adsorbent added is too small, it will easily affect the adsorption effect of iron and ferrous ions in the ammonium-free plating solution, thereby increasing the iron content in the ammonium-free plating solution, affecting the plating effect of the ammonium-free plating solution, as well as the uniformity and adhesion of the zinc plating layer.

[0068] Compared with Example 1, Comparative Example 3 increased the amount of iron removal adsorbent added. Compared with Example 1, Comparative Example 2 did not show a significant change in the corrosion rate, indicating that when the amount of iron removal adsorbent added is too large, the effect on the ammonium-free plating solution is small. The content of iron ions and ferrous ions in the ammonium-free plating solution is low, and the adsorption capacity of some iron removal adsorbents is small, resulting in waste. Therefore, the amount of iron removal adsorbent added does not need to be too large.

[0069] 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 processing technology for corrosion-resistant galvanized steel sheet, characterized in that: Includes the following steps: Degreasing: Immerse the substrate in a degreasing agent for degreasing and oil removal treatment for 25-40 minutes; Pickling: Immerse the degreased substrate in hydrochloric acid solution for pickling. The concentration of hydrochloric acid solution is 5-20wt%, and the pickling time is 5-10min. After pickling, rinse with clean water for 1-2min. Fluxing: The pickled substrate is immersed in an ammonium-free flux solution at a flux temperature of 40-60℃ for 1-3 minutes. The ammonium-free flux solution includes 80-100 g / L zinc chloride, 30-50 g / L sodium chloride, 8-10 g / L potassium chloride, and 1-1.2 g / L iron removal adsorbent. The iron removal adsorbent includes the following raw materials: solution A and solution B in a volume ratio of 9-11:

1. Solution A includes myricetin and water, with the amount of myricetin added being 3-6 wt% of water. Solution B includes glutaraldehyde. Hot-dip galvanizing: The substrate after fluxing is immersed in molten zinc at a temperature of 450-520℃ for 4-8 minutes. Passivation: Immerse the hot-dip galvanized and cooled substrate in the passivation solution for 2-3 minutes, and rinse with clean water 2-5 times.

2. The processing technology of the anti-corrosion galvanized sheet according to claim 1, characterized in that: The ammonium-free plating solution also includes 3.5-8.1 g / L of nickel chloride.

3. The processing technology of the anti-corrosion galvanized sheet according to claim 1, characterized in that: The ammonium-free flux also includes a surfactant, which is a compound of sodium dodecyl sulfate and sodium lauramide glycidate. The molar ratio of sodium dodecyl sulfate to sodium lauramide glycidate is 1:0.42-1.51, and the concentration of sodium dodecyl sulfate in the ammonium-free flux is 0.068-0.12 g / L.

4. The processing technology of the anti-corrosion galvanized sheet according to claim 3, characterized in that: The A solution also includes aminated silica, and the mass ratio of aminated silica to bayberry tannin is 1:0.4-0.

6.

5. The processing technology of the anti-corrosion galvanized sheet according to claim 4, characterized in that: The preparation method of the iron removal adsorbent includes the following steps: adding aminated silica and myricetin to water, stirring for 10-12 hours to obtain solution A, adding solution B to solution A, crosslinking at 30-40℃ for 22-24 hours, filtering, washing, and vacuum drying at 35-40℃ for 23-24 hours to obtain the iron removal adsorbent.

6. The processing technology of a corrosion-resistant galvanized sheet according to claim 1 or 3, characterized in that: The pH of the ammonium-free flux is 3.8-4.

3.

7. The processing technology of the anti-corrosion galvanized sheet according to claim 1, characterized in that: The hydrochloric acid solution is circulated through the adsorption column at a flow rate of 50-55 mL / h. The adsorption column comprises the following raw materials: ion exchange resin and chelating agent. The amount of chelating agent added is 0.4-0.6 wt% of the ion exchange resin.

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