Treatment process for improving adhesive force of hot galvanizing

Abstract

The invention relates to the technical field of hot dip coating processes, in particular to a treatment process for improving adhesive force of hot dip galvanizing, which comprises the following steps: carrying out surface oxidation treatment on a base material to oxidize Si on the surface of the base material to obtain an oxidized base material; sequentially carrying out alkali washing, water washing and acid-sand co-washing treatment on the oxidized base material to remove surface impurities so as to obtain a pretreated base material; washing and drying the pretreated base material, then immersing the pretreated base material in a plating assisting solution, taking out the pretreated base material and drying the pretreated base material after plating assisting is finished to obtain a coated base material; and the coating substrate is immersed in the Zn-0. 1Ni alloy liquid, a magnetic field is applied in the hot-dip galvanizing treatment period, and after hot-dip galvanizing is finished, the coating substrate is taken out and cooled to the room temperature. According to the method, oxidation treatment, acid-sand co-washing treatment and magnetic field hot-dip galvanizing treatment are combined for the base material, so that the coating structure is more compact, the corrosion resistance of the coating is improved, and meanwhile, the adhesive force between the coating and the base material is also increased.

Description

Technical Field

[0001] The present invention relates to the technical field of hot-dip plating processes, and specifically to a treatment process for improving the adhesion of hot-dip galvanizing. Background Art

[0002] Hot-dip galvanizing, also known as hot-dip zinc plating, is a method of obtaining a metal coating by immersing steel components in molten zinc. Compared with other protection means, it has obvious advantages. Its operation and control are reliable, the coating is easy to detect, and the process operation is simple. It is widely used in fields such as automobiles, construction, and electricity.

[0003] Traditional hot-dip galvanizing processes usually include water washing, alkali washing, acid pickling, fluxing, and galvanizing treatment. For steel with a low silicon content, this kind of hot-dip zinc treatment can meet the requirements. However, for steel with a high silicon content, the high silicon content will promote the iron-zinc reaction, resulting in an increase in the coating thickness, a dull coating surface, and the ζ phase being discontinuous granular, causing the coating structure to be relatively loose and the bonding strength between the coating and the steel to deteriorate. Based on this, a treatment process for improving the adhesion of hot-dip galvanizing is proposed. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a treatment process for improving the adhesion of hot-dip galvanizing. By jointly using oxidation treatment, acid-sand co-washing treatment, and magnetic field hot-dip zinc treatment on the substrate, the coating structure becomes more dense, the corrosion resistance of the coating itself is improved, and at the same time, the adhesion between the coating and the substrate is increased.

[0005] To achieve the above object, the present invention provides the following technical solution: A treatment process for improving the adhesion of hot-dip galvanizing, including the following steps, (1) Perform surface oxidation treatment on the substrate to oxidize the Si on its surface to obtain an oxidized substrate; (2) Perform alkali washing, water washing, and acid-sand co-washing treatment on the oxidized substrate in sequence to remove surface impurities and obtain a pretreated substrate; (3) Wash and dry the pretreated substrate, then immerse it in a fluxing solution. After fluxing, take it out and dry it to obtain a coated substrate; (4) Immerse the coated substrate in a Zn-0.1Ni alloy solution, apply a magnetic field during the hot-dip zinc treatment, and after the hot-dip zinc treatment is completed, take it out and cool it to room temperature.

[0006] Preferably, in step (1), by mass percentage, the substrate includes the following components: C 3.6%, Si 2.9%, Mn 0.2%, Mg 0.044%, Re 0.035%, P ≤ 0.06, S ≤ 0.025%, and the balance is Fe.

[0007] Preferably, in step (1), the surface oxidation treatment method is as follows: put the substrate, Cr and Cr2O3 (chromium trioxide) mixed powder into a tubular furnace, perform high-temperature treatment at 750 - 800 °C for 3 - 5 h, and after cooling, the oxidized substrate is obtained.

[0008] Preferably, the mass ratio of the Cr powder to the Cr2O3 powder is 1:(2 - 3).

[0009] Preferably, in step (2), the acid-sand co-washing treatment method is as follows: S1. Add quartz sand to the hydrochloric acid solution to obtain an acid-sand material; S2. Put the oxidized substrate that has been alkali-washed and water-washed into the acid-sand material, maintain ultrasonic treatment, and after the treatment is completed, the pretreated substrate is obtained.

[0010] Preferably, in step S1, the mass fraction of the hydrochloric acid solution is 10 - 20%.

[0011] Preferably, in step S2, the ultrasonic treatment power is 220 - 280 W, and the ultrasonic treatment time is 2 - 3 min.

[0012] Preferably, in step (3), the preparation method of the flux solution is as follows: add alkylphenol polyoxyethylene ether to the 220 g / L NH4Cl-ZnCl2 (ammonium chloride-zinc chloride) aqueous solution, and mix evenly to obtain the flux solution; the mass ratio of NH4Cl to ZnCl2 is 1:(0.8 - 1); the material-liquid ratio of alkylphenol polyoxyethylene ether to the NH4Cl-ZnCl2 aqueous solution is (15 - 20):1 g / L.

[0013] Preferably, in step (3), the fluxing temperature is 70 - 75 °C, and the fluxing time is 4 - 5 min.

[0014] Preferably, in step (4), the hot-dip galvanizing temperature is 455 - 460 °C, the hot-dip galvanizing time is 100 - 120 s; the applied magnetic field strength is 10 - 15 mT.

[0015] The present invention provides a treatment process for improving the adhesion of hot-dip galvanizing, which has the following beneficial effects compared with the prior art: The present invention combines oxidation treatment, acid-sand co-washing treatment and magnetic field hot-dip galvanizing treatment for the substrate, making the coating structure more dense, improving the corrosion resistance of the coating itself, and at the same time increasing the adhesion between the coating and the substrate. Specifically, the oxidation treatment oxidizes Si on the substrate surface into SiO2, and during the subsequent acid-sand co-washing treatment, SiO2 can be well stripped, reducing the Si content on the substrate surface and avoiding the problems of coating thickening and loose coating structure caused by high Si content.

[0016] The present invention changes the traditional pickling process. Quartz sand is added to the pickling solution. Through ultrasonic treatment, the quartz sand moves disorderly, continuously frictional impacts on the surface of the substrate, and can better and more efficiently remove impurities such as SiO2 on the surface of the substrate, and clean more thoroughly. Moreover, through the frictional impact of the quartz sand, a micro-rough structure will be formed on the surface of the substrate, and through mechanical interlocking, it helps to improve the bonding strength between the substrate and the coating.

[0017] In the present invention, a magnetic field is applied during hot-dip galvanizing, which accelerates the flow of the Zn-Ni alloy liquid, ensures the uniformity of the coating, and can reduce the porosity of the coating, thereby improving the bonding strength between the coating and the substrate and the corrosion resistance of the coating itself. Description of the Drawings

[0018] The drawings described herein are used to provide a further understanding of the present application and form a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation to the present application. In the drawings: Figure 1 It is the morphology diagram of the products after corrosion in Example 3 of the present invention and Comparative Examples 1-4; Figure 2 It is the morphology diagram of the coating interface of the products in Example 3 of the present invention and Comparative Example 1; Figure 3 It is the surface morphology of the oxidized substrate in Example 3 of the present invention. Detailed Embodiments

[0019] The following examples are used to detail the implementation manners of the present application, so as to fully understand how the present application uses technical means to solve technical problems and achieve the realization process of technical effects and implement accordingly.

[0020] The substrate used in the present invention has the specific components shown in Table 1.

[0021] Table 1 Substrate Components

[0022] Example 1 A treatment process for improving the adhesion of hot-dip galvanizing includes the following steps: (1) Perform surface oxidation treatment on the substrate to oxidize Si on its surface to obtain an oxidized substrate; The surface oxidation treatment method is: put the substrate, Cr and Cr2O3 mixed powder (the mass ratio of Cr powder to Cr2O3 powder is 1:3) into a tube furnace, the substrate does not contact the mixed powder, and perform high-temperature treatment at 750 °C for 5 h, and after cooling, the oxidized substrate is obtained.

[0023] (2) The oxidized substrate is successively subjected to alkali washing, water washing, and acid-sand co-washing treatments to remove surface impurities, and a pretreated substrate is obtained. The method for alkali washing treatment is as follows: Immerse the oxidized substrate in a 15wt% NaOH solution and wash it at 75°C for 5 minutes. The method for acid-sand co-washing treatment is as follows: S1. Add quartz sand to a 10wt% hydrochloric acid solution to obtain an acid-sand material; S2. Put the oxidized substrate that has been alkali-washed and water-washed into the acid-sand material, and perform ultrasonic treatment at a power of 280W for 2 minutes. After the treatment is completed, the pretreated substrate is obtained.

[0024] (3) The pretreated substrate is washed with water and dried, then immersed in a fluxing solution, fluxed at 75°C for 4 minutes. After the fluxing is completed, take it out and dry it to obtain a coated substrate. The method for preparing the fluxing solution is as follows: Add alkylphenol polyoxyethylene ether to a 220g / L NH4Cl-ZnCl2 aqueous solution and mix evenly to obtain the fluxing solution; among them, the mass ratio of NH4Cl to ZnCl2 is 1:1; the material ratio of alkylphenol polyoxyethylene ether to the NH4Cl-ZnCl2 aqueous solution is 15:1 g / L.

[0025] (4) Immerse the coated substrate in a Zn-0.1Ni (0.1 represents the mass fraction) alloy solution, perform hot-dip galvanizing at 460°C for 100 s, apply a magnetic field with a strength of 15 mT during the hot-dip galvanizing process. After the hot-dip galvanizing is completed, take it out and cool it to room temperature.

[0026] Example 2 A treatment process for improving the adhesion of hot-dip galvanizing includes the following steps: (1) Perform surface oxidation treatment on the substrate to oxidize the Si on its surface to obtain an oxidized substrate. The method for surface oxidation treatment is as follows: Put the substrate, Cr and Cr2O3 mixed powder (the mass ratio of Cr powder to Cr2O3 powder is 1:2) into a tubular furnace. The substrate does not contact the mixed powder. Perform high-temperature treatment at 800°C for 3 hours. After cooling, the oxidized substrate is obtained.

[0027] (2) The oxidized substrate is successively subjected to alkali washing, water washing, and acid-sand co-washing treatments to remove surface impurities, and a pretreated substrate is obtained. The method for alkali washing treatment is as follows: Immerse the oxidized substrate in a 15wt% NaOH solution and wash it at 75°C for 5 minutes. The method for acid-sand co-washing treatment is as follows: S1. Add quartz sand to a 20wt% hydrochloric acid solution to obtain an acid-sand material; S2. Put the oxidized substrate that has been alkali-washed and water-washed into the acid-sand material, and perform ultrasonic treatment at a power of 220W for 2 minutes. After the treatment is completed, the pretreated substrate is obtained.

[0028] (3) Wash and dry the pretreated substrate, then immerse it in the fluxing solution, flux at 70 °C for 5 min, after fluxing is completed, take it out and dry to obtain the coated substrate; The preparation method of the fluxing solution is as follows: Add alkylphenol polyoxyethylene ether to the NH4Cl-ZnCl2 aqueous solution at 220 g / L, and mix evenly to obtain the fluxing solution; among them, the mass ratio of NH4Cl to ZnCl2 is 1:0.8; the material ratio of alkylphenol polyoxyethylene ether to the NH4Cl-ZnCl2 aqueous solution is 20:1 g / L.

[0029] (4) Immerse the coated substrate in the Zn-0.1Ni (0.1 represents the mass fraction) alloy solution, hot-dip galvanize at 455 °C for 120 s, apply a magnetic field with a strength of 10 mT during the hot-dip galvanizing process, after hot-dip galvanizing is completed, take it out and cool it to room temperature.

[0030] Example 3 A treatment process for improving the adhesion of hot-dip galvanizing, including the following steps: (1) Perform surface oxidation treatment on the substrate to oxidize the Si on its surface to obtain an oxidized substrate, and its surface morphology is as Figure 3 shown; The surface oxidation treatment method is as follows: Put the substrate, Cr and Cr2O3 mixed powder (the mass ratio of Cr powder to Cr2O3 powder is 1:2) into a tube furnace, the substrate does not contact the mixed powder, perform high-temperature treatment at 770 °C for 4 h, and after cooling, the oxidized substrate is obtained.

[0031] (2) Perform alkali washing, water washing and acid-sand co-washing treatment on the oxidized substrate in sequence to remove surface impurities and obtain the pretreated substrate; The alkali washing treatment method is as follows: Immerse the oxidized substrate in a 15 wt% NaOH solution and wash at 75 °C for 5 min; The acid-sand co-washing treatment method is as follows: S1. Add quartz sand to a 15 wt% hydrochloric acid solution to obtain an acid-sand material; S2. Put the oxidized substrate that has been alkali-washed and water-washed into the acid-sand material, and perform ultrasonic treatment at a power of 250 W for 2.5 min. After the treatment is completed, the pretreated substrate is obtained.

[0032] (3) Wash and dry the pretreated substrate, then immerse it in the fluxing solution, flux at 70 °C for 5 min, after fluxing is completed, take it out and dry to obtain the coated substrate; The preparation method of the fluxing solution is as follows: Add alkylphenol polyoxyethylene ether to the NH4Cl-ZnCl2 aqueous solution at 220 g / L, and mix evenly to obtain the fluxing solution; among them, the mass ratio of NH4Cl to ZnCl2 is 1:0.8; the material ratio of alkylphenol polyoxyethylene ether to the NH4Cl-ZnCl2 aqueous solution is 18:1 g / L.

[0033] Immerse the coated substrate in a Zn-0.1Ni (0.1 represents the mass fraction) alloy solution, hot-dip galvanize it at 460 °C for 110 s, apply a magnetic field with a strength of 12 mT during the hot-dip galvanizing process, and after the hot-dip galvanizing is completed, take it out and cool it to room temperature.

[0034] In this example, the coating interface morphology diagram of the obtained product is as Figure 2 shown in a. It can be seen that the coating structure is relatively dense, which has a positive effect on improving adhesion and corrosion resistance.

[0035] Comparative Example 1 A treatment process for improving the adhesion of hot-dip galvanizing includes the following steps: (1) Perform alkali cleaning, water washing, and acid sand co-washing on the substrate in sequence to remove surface impurities and obtain a pretreated substrate; The alkali cleaning treatment method is: Immerse the oxidized substrate in a 15wt% NaOH solution and clean it at 75 °C for 5 min; The acid sand co-washing treatment method is: S1. Add quartz sand to a 15wt% hydrochloric acid solution to obtain an acid sand material; S2. Put the substrate that has been alkali-cleaned and water-washed into the acid sand material and perform ultrasonic treatment at a power of 250 W for 2.5 min. After the treatment is completed, the pretreated substrate is obtained.

[0036] (2) Wash and dry the pretreated substrate, then immerse it in a fluxing solution, flux it at 70 °C for 5 min, take it out and dry it after the fluxing is completed to obtain a coated substrate; The preparation method of the fluxing solution is: Add alkylphenol polyoxyethylene ether to a 220 g / L NH4Cl-ZnCl2 aqueous solution and mix evenly to obtain the fluxing solution; among them, the mass ratio of NH4Cl to ZnCl2 is 1:0.8; the material ratio of alkylphenol polyoxyethylene ether to the NH4Cl-ZnCl2 aqueous solution is 18:1 g / L.

[0037] (3) Immerse the coated substrate in a Zn-0.1Ni (0.1 represents the mass fraction) alloy solution, hot-dip galvanize it at 460 °C for 110 s, apply a magnetic field with a strength of 12 mT during the hot-dip galvanizing process, and after the hot-dip galvanizing is completed, take it out and cool it to room temperature.

[0038] In this example, the coating interface morphology diagram of the obtained product is as Figure 2 shown in b. It can be seen that the coating structure is relatively loose, which will reduce the adhesion and corrosion resistance of the coating.

[0039] Comparative Example 2 A treatment process for improving the adhesion of hot-dip galvanizing includes the following steps: (1) Perform surface oxidation treatment on the substrate to oxidize the Si on its surface and obtain an oxidized substrate; The surface oxidation treatment method is as follows: Put the substrate, Cr and Cr2O3 mixed powder (the mass ratio of Cr powder to Cr2O3 powder is 1:2) into a tubular furnace, with the substrate not in contact with the mixed powder. Perform high-temperature treatment at 770 °C for 4 h, and after cooling, the oxidized substrate is obtained.

[0040] (2) Perform alkali washing, water washing, and acid washing on the oxidized substrate in sequence to remove surface impurities and obtain a pretreated substrate. The alkali washing treatment method is: Immerse the oxidized substrate in a 15 wt% NaOH solution and wash at 75 °C for 5 min. The acid washing treatment method is: Put the oxidized substrate that has been alkali washed and water washed into a 15 wt% hydrochloric acid solution, perform ultrasonic treatment at a power of 250 W for 2.5 min. After the treatment is completed, the pretreated substrate is obtained.

[0041] (3) Wash the pretreated substrate with water and dry it, then immerse it in a fluxing solution, perform fluxing at 70 °C for 5 min. After the fluxing is completed, take it out and dry it to obtain a coated substrate. The preparation method of the fluxing solution is: Add alkylphenol polyoxyethylene ether to a 220 g / L NH4Cl-ZnCl2 aqueous solution, and mix evenly to obtain the fluxing solution; among them, the mass ratio of NH4Cl to ZnCl2 is 1:0.8; the material ratio of alkylphenol polyoxyethylene ether to the NH4Cl-ZnCl2 aqueous solution is 18:1 g / L.

[0042] (4) Immerse the coated substrate in a Zn-0.1Ni (0.1 represents the mass fraction) alloy solution, perform hot-dip galvanizing at 460 °C for 110 s, apply a magnetic field with a strength of 12 mT during the hot-dip galvanizing process. After the hot-dip galvanizing is completed, take it out and cool it to room temperature.

[0043] Comparative Example 3 A treatment process for improving the adhesion of hot-dip galvanizing includes the following steps: (1) Perform surface oxidation treatment on the substrate to oxidize Si on its surface and obtain an oxidized substrate. The surface oxidation treatment method is: Put the substrate, Cr and Cr2O3 mixed powder (the mass ratio of Cr powder to Cr2O3 powder is 1:2) into a tubular furnace, with the substrate not in contact with the mixed powder. Perform high-temperature treatment at 770 °C for 4 h, and after cooling, the oxidized substrate is obtained.

[0044] (2) Perform alkali washing, water washing, and acid sand co-washing on the oxidized substrate in sequence to remove surface impurities and obtain a pretreated substrate. The alkali washing treatment method is: Immerse the oxidized substrate in a 15 wt% NaOH solution and wash at 75 °C for 5 min. The acid-sand co-washing treatment method is as follows: S1. Add quartz sand to a 15wt% hydrochloric acid solution to obtain an acid-sand material; S2. Put the oxidized substrate that has been alkali-washed and water-washed into the acid-sand material, and perform ultrasonic treatment at a power of 250W for 2.5min. After the treatment is completed, the pretreated substrate is obtained.

[0045] (3) Wash the pretreated substrate with water and dry it, then immerse it in a fluxing solution, flux at 70°C for 5min. After the fluxing is completed, take it out and dry it to obtain a coated substrate; The preparation method of the fluxing solution is: Add alkylphenol polyoxyethylene ether to an aqueous solution of NH4Cl-ZnCl2 at 220g / L, and mix evenly to obtain the fluxing solution; among them, the mass ratio of NH4Cl to ZnCl2 is 1:0.8; the material ratio of alkylphenol polyoxyethylene ether to the aqueous solution of NH4Cl-ZnCl2 is 18:1g / L.

[0046] (4) Immerse the coated substrate in a Zn-0.1Ni (0.1 represents the mass fraction) alloy solution, perform hot-dip galvanizing at 460°C for 110s. After the hot-dip galvanizing is completed, take it out and cool it to room temperature.

[0047] Comparative Example 4 A treatment process for improving the adhesion of hot-dip galvanizing includes the following steps: (1) Perform surface oxidation treatment on the substrate to oxidize the Si on its surface to obtain an oxidized substrate; The surface oxidation treatment method is: Put the substrate, Cr and Cr2O3 mixed powder (the mass ratio of Cr powder to Cr2O3 powder is 1:2) into a tubular furnace, the substrate does not contact the mixed powder, perform high-temperature treatment at 770°C for 4h, and after cooling, the oxidized substrate is obtained.

[0048] (2) Perform alkali washing, water washing and acid-sand co-washing treatment on the oxidized substrate in sequence to remove surface impurities and obtain a pretreated substrate; The alkali washing treatment method is: Immerse the oxidized substrate in a 15wt% NaOH solution and wash it at 75°C for 5min; The acid-sand co-washing treatment method is as follows: S1. Add quartz sand to a 15wt% hydrochloric acid solution to obtain an acid-sand material; S2. Put the oxidized substrate that has been alkali-washed and water-washed into the acid-sand material, and perform ultrasonic treatment at a power of 250W for 2.5min. After the treatment is completed, the pretreated substrate is obtained.

[0049] (3) Wash the pretreated substrate with water and dry it, then immerse it in a fluxing solution (an aqueous solution of NH4Cl-ZnCl2 at 220g / L, where the mass ratio of NH4Cl to ZnCl2 is 1:0.8), flux at 70°C for 5min. After the fluxing is completed, take it out and dry it to obtain a coated substrate; (4) Immerse the coated substrate into the Zn-0.1Ni (0.1 represents mass fraction) alloy liquid, perform hot-dip galvanizing at 460 °C for 110 s, apply a magnetic field with a strength of 12 mT during the hot-dip galvanizing process, and after the hot-dip galvanizing is completed, take it out and cool it to room temperature.

[0050] Quality inspection 1. Using the products in Examples 1-3 and Comparative Examples 1-4 as test specimens, use a WS-2005 type automatic scratch tester for coating adhesion to detect the bonding strength between the substrate and the Zn-Ni coating in the products. The specific test results are shown in Table 2.

[0051] Table 2 Bonding strength

[0052] As can be seen from the above table: The bonding strength between the Zn-Ni coating and the substrate in the products of Examples 1-3 all exceeded 39 N, indicating that the adhesion effect of the Zn-Ni coating is excellent; compared with Example 3, in Comparative Example 1, the substrate was not oxidized, and the excessive Si content on the surface seriously affected the bonding between the Zn-Ni coating and the substrate, resulting in a poor adhesion effect; compared with Example 3, in Comparative Example 2, there was no abrasive treatment during pickling. On the one hand, it was difficult to fully remove the silicon oxide slag layer on the substrate surface, and on the other hand, it was impossible to roughen the substrate surface, thus reducing the adhesion effect of the Zn-Ni coating; compared with Example 3, in Comparative Example 3, no magnetic field was applied during hot-dip plating, resulting in a slight decrease in the bonding strength between the Zn-Ni coating and the substrate.

[0053] 2. Using the products in Example 3 and Comparative Examples 1-4 as test specimens, conduct corrosion resistance testing according to the standard of GB / T 10125-2021. The specific test results are shown in Table 3.

[0054] Table 3 Corrosion resistance

[0055] From the above table and combined with Figure 1 It can be seen that: Figure 1 a is the morphology diagram of the product after corrosion in Example 3. The corrosion surface is flat and dense, which is also the reason for the smaller average corrosion rate; Figure 1 b is the morphology diagram of the product after corrosion in Comparative Example 4. The whole is also relatively flat and dense; Figure 1 c is the morphology diagram of the product after corrosion in Comparative Example 3. Figure 1 d is the morphology diagram of the product after corrosion in Comparative Example 2. It can be seen that the corrosion surfaces of both are uneven to varying degrees; Figure 1 e is the morphology diagram of the product after corrosion in Comparative Example 1. The corrosion is obvious, and holes even appear in some positions, and its average corrosion rate is relatively large.

[0056] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A treatment process for improving the adhesion of hot-dip galvanizing, characterized in that: The following steps are involved: (1) placing the substrate, Cr and Cr2O3 mixed powder into a tube furnace and subjecting the mixture to high temperature treatment at 750-800°C for 3-5h to oxidize Si on the substrate surface, and obtaining an oxidized substrate after cooling; (2) sequentially performing alkali washing, water washing, and acid-sand co-washing treatments on the oxidized substrate to remove surface impurities and obtain a pretreated substrate; (3) washing the pretreated substrate with water and drying it, then immersing it in a plating solution, and after the plating is completed, taking it out and drying it to obtain a coated substrate; (4) Immerse the coated substrate in a Zn-0.1Ni alloy solution, apply a magnetic field during the hot-dip galvanizing treatment, and take it out after the hot-dip galvanizing is completed and cool it to room temperature.

2. A treatment process for improving hot dip galvanizing adhesion according to claim 1, characterized in that: In step (1), the substrate includes the following components, measured by mass percentage: C 3.6%, Si 2.9%, Mn 0.2%, Mg 0.044%, Re 0.035%, P≤0.06, S ≤0.025%, and the balance is Fe.

3. A treatment process for improving hot dip galvanizing adhesion according to claim 1, characterized in that: In the mixed powder of Cr and Cr2O3, the mass ratio of Cr powder to Cr2O3 powder is 1:(2-3).

4. A treatment process for improving hot dip galvanizing adhesion according to claim 1, characterized in that: In step (2), the acid sand co-washing treatment method is: S1, adding quartz sand to hydrochloric acid solution to obtain acid sand material; S2. Put the oxidized substrate washed with alkali and water into acid sand material and keep ultrasonic treatment until the treatment is completed to obtain the pretreated substrate.

5. A treatment process for improving hot dip galvanizing adhesion according to claim 4, characterized in that: In step S1, the mass fraction of the hydrochloric acid solution is 10-20%.

6. A treatment process for improving hot dip galvanizing adhesion according to claim 4, characterized in that: In step S2, the ultrasonic treatment power is 220-280W, and the ultrasonic treatment time is 2-3min.

7. The process for improving hot-dip galvanizing adhesion according to claim 1, characterized in that: In step (3), the method for preparing the plating solution is as follows: adding alkylphenol polyoxyethylene ether to a 220 g / L NH4Cl-ZnCl2 aqueous solution and mixing well to obtain the plating solution; The mass ratio of NH4Cl and ZnCl2 is 1:(0.8-1); the solid-liquid ratio of alkylphenol polyoxyethylene ether to NH4Cl-ZnCl2 aqueous solution is (15-20):1g / L.

8. The process for improving hot-dip galvanizing adhesion according to claim 1, characterized in that: In step (3), the plating temperature is 70-75°C and the plating time is 4-5 minutes.

9. The process for improving hot-dip galvanizing adhesion according to claim 1, characterized in that: In step (4), the hot-dip galvanizing temperature is 455-460°C, the hot-dip galvanizing time is 100-120s; and the applied magnetic field strength is 10-15mT.

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