Processing technology of galvanized steel strip
By employing physical cleaning, vacuum deposition of zinc-based thin films, and nanocomposite passivation treatment, the problems of poor adhesion and insufficient corrosion resistance of galvanized steel strips have been solved, improving the density and corrosion resistance of the coating and extending the service life of the product.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-01-13
- Publication Date
- 2026-04-03
AI Technical Summary
Incomplete pretreatment of traditional galvanized steel strips leads to poor coating adhesion, insufficient corrosion resistance, and limited passivation film performance, thus affecting the product's service life.
The steel strip surface is heated using a physical cleaning method and dry ice microparticles are sprayed. This is combined with vacuum deposition of zinc-based thin films and nanocomposite passivation treatment to form a dense zinc-based thin film and passivation film, which improves surface cleanliness and coating adhesion.
It achieves excellent adhesion and long-lasting corrosion resistance of the coating, enhances the mechanical strength and wear resistance of the passivation film, and significantly extends the service life of the product.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of galvanized steel strip manufacturing technology, specifically, to a processing technology for galvanized steel strip. Background Technology
[0002] Galvanized steel strip, as an important metallic material, is widely used in many fields such as construction, automobiles, home appliances, and machinery manufacturing due to its excellent corrosion resistance and good mechanical properties. Its core function lies in forming a zinc coating on the surface of the steel strip, utilizing the sacrificial anodic protection of zinc to effectively slow down the corrosion process of the steel substrate, thereby extending the product's service life. As various industries continue to raise their requirements for material performance, the quality standards for galvanized steel strip are becoming increasingly stringent, demanding not only excellent corrosion resistance but also higher levels of surface cleanliness, coating adhesion, and passivation film performance.
[0003] Traditional pretreatment processes, whether chemical cleaning or mechanical grinding, struggle to completely remove contaminants from the steel strip surface. Chemical cleaning may be incomplete due to factors such as solution concentration and cleaning time, leaving residual grease and oxides that affect the adhesion between the coating and the steel strip substrate. Mechanical grinding, on the other hand, easily leaves micro-scratches and impurities on the steel strip surface, providing erosion channels for corrosive media and reducing the coating's corrosion resistance. Incomplete pretreatment results in contaminants and defects on the steel strip surface, leading to insufficient adhesion between the coating and the substrate. During subsequent processing and use, the coating is prone to peeling and flaking, severely impacting the quality and performance of the galvanized steel strip. Furthermore, the reaction characteristics of the steel strip with the zinc bath in hot-dip galvanizing and uneven current distribution in electro-galvanizing can also lead to unsatisfactory coating adhesion. Simultaneously, the passivation film formed by traditional passivation processes has limited performance and cannot effectively isolate the zinc layer from corrosive media. In harsh environments, galvanized steel strips are prone to rapid corrosion phenomena such as white rust and red rust, shortening the product's service life. Based on these findings, this invention proposes a processing technology for galvanized steel strip. Summary of the Invention
[0004] This invention proposes a processing technology for galvanized steel strip, which solves the problems of incomplete cleaning, poor coating adhesion, and insufficient corrosion resistance of traditional galvanized steel strip. It improves the surface cleanliness and activation effect of the steel strip, enhances the density, adhesion, and long-term anti-corrosion performance of the coating, and strengthens the mechanical strength and wear resistance of the passivation film, effectively delaying electrochemical corrosion and ensuring the excellent comprehensive performance of the galvanized steel strip.
[0005] The technical solution of the present invention is as follows: In a first aspect, the present invention proposes a processing technology for galvanized steel strip, the steps of which include: S1. Physical pretreatment: Physical cleaning methods are used to remove grease and oxide layer from the surface of the steel strip; S2, Vacuum deposition of zinc-based thin film: In a vacuum environment, a continuous zinc-based thin film is formed on the surface of the steel strip after step S1 by vapor deposition. S3. Post-treatment: The galvanized steel strip is subjected to nano-composite passivation treatment with passivation solution to obtain galvanized steel strip.
[0006] As a further technical solution, the physical pretreatment in step S1 specifically involves heating the surface of the steel strip to 250-320°C, using dry ice particles with an average particle size of 20-150μm, and spraying them onto the heated steel strip surface under a pressure of 0.5-2.0MPa to remove contaminants through thermal shock and physical collision.
[0007] As a further technical solution, in step S2, the vapor deposition method is pulsed magnetron sputtering; the vacuum level of the vacuum environment is not higher than 5.0 × 10⁻⁶. -2 Pa; During the vapor deposition, the steel strip temperature is maintained at 100-180℃.
[0008] As a further technical solution, in step S2, the sputtering target used in the pulsed magnetron sputtering includes one or both of pure zinc target and zinc-magnesium alloy target.
[0009] In this invention, when pulsed magnetron sputtering is used, and the sputtering target includes two types of pure zinc target and zinc-magnesium alloy target, it is co-sputtering by pure zinc target and zinc-magnesium alloy target.
[0010] As a further technical solution, when the sputtering target used in the pulsed magnetron sputtering includes a zinc-magnesium alloy target, the mass percentage of magnesium in the zinc-magnesium alloy target is 3%-5%.
[0011] As a further technical solution, in step S3, the preparation method of the passivation solution includes: mixing deionized water and ethanol, adjusting the pH to 4.0-5.0 with acetic acid; adding silane coupling agent KH550 under stirring, and hydrolyzing for 30-40 minutes; then adding nano-titanium dioxide powder and dispersant polyethylene glycol, and ultrasonically dispersing for 30-40 minutes to obtain a stable nano-composite passivation solution sol.
[0012] As a further technical solution, the volume ratio of deionized water to ethanol is 1:3-1:5; the amount of silane coupling agent KH550 added accounts for 3%-5% of the total mass of the mixed solution; the amount of nano titanium dioxide powder added accounts for 1%-3% of the total mass of the liquid; and the amount of polyethylene glycol added accounts for 0.1%-0.5% of the mass of nano titanium dioxide powder.
[0013] As a further technical solution, the average particle size of the nano-titanium dioxide powder is 20-40 nm.
[0014] As a further technical solution, the passivation treatment step includes: rinsing the galvanized steel strip with deionized water, applying a passivation solution to the cleaned steel strip surface to form a wet film, and obtaining a steel strip coated with a wet film; heating and curing the steel strip coated with the wet film to form a nanocomposite passivation film; the thickness of the nanocomposite passivation film is 50-100 nm.
[0015] As a further technical solution, the heating and curing step is to bake at 120-140℃ for 10-20 seconds.
[0016] The working principle and beneficial effects of this invention are as follows: This invention employs a physical cleaning method, specifically heating the steel strip surface to 250-320℃ and then spraying dry ice particles with an average particle size of 20-150μm onto the heated steel strip surface under a pressure of 0.5-2.0MPa. This utilizes thermal shock and physical collision to remove contaminants. The high-temperature heating reduces grease viscosity and weakens the adhesion of the oxide layer. The thermal shock effect generated by dry ice spraying works synergistically with these properties, achieving deep cleaning and surface activation. This results in a clean, active surface, providing a good foundation for subsequent vacuum deposition of zinc-based thin films, thereby achieving excellent coating adhesion and corrosion resistance.
[0017] In the vacuum deposition of zinc-based thin films, the sputtering targets used in this invention include pure zinc targets, zinc-magnesium alloy targets, or co-sputtering of pure zinc targets and zinc-magnesium alloy targets, with the magnesium content in the zinc-magnesium alloy target being 3%-5% by mass. Introducing an appropriate amount of magnesium into the coating to form a Zn-Mg alloy optimizes the coating's microstructure. Magnesium alters the crystal structure of the coating, making it more compact. Simultaneously, utilizing a sacrificial anode protection mechanism, when the coating is locally damaged, magnesium, as a more reactive metal, is preferentially corroded, thus protecting the zinc layer and significantly improving the coating's long-term corrosion resistance. During the deposition process, the steel strip temperature is maintained at 100-180℃. This temperature ensures that the plating atoms have sufficient energy to migrate on the steel strip surface, allowing for sufficient diffusion and rearrangement, forming a dense, uniform, and firmly bonded coating. If the temperature is below 100℃, the coating adhesion, density, and corrosion resistance are unsatisfactory; if the temperature is above 180℃, some elements may volatilize, the coating may become over-oxidized, or stress may be generated, leading to a decrease in bending performance and long-term corrosion resistance.
[0018] In this invention, the nanocomposite passivation film not only provides an additional physical barrier but also effectively isolates the corrosive medium from contact with the zinc layer and slows down the electrochemical corrosion process. Nano-titanium dioxide particles play a key scaffolding and reinforcing role in the passivation film; their high specific surface area and excellent physicochemical properties significantly improve the film's mechanical strength, wear resistance, and barrier effect. If the post-passivation treatment step is omitted, the product's corrosion resistance will deteriorate drastically, with white and red rust appearing much earlier, leading to rapid corrosion in salt water immersion. The nanocomposite passivation treatment, combined with the preceding physical pretreatment and vacuum deposition of zinc-based thin films, works synergistically to ensure the excellent overall performance of the galvanized steel strip. Detailed Implementation
[0019] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.
[0020] Example 1 This embodiment provides a processing technology for galvanized steel strip, the steps of which include: (1) Physical pretreatment: The cold-rolled steel strip with a width of 1250 mm and a thickness of 0.8 mm is continuously passed through the preheating furnace. The surface temperature of the steel strip is precisely controlled at 280℃ by a combination of induction heating and hot air circulation heating. Then, the steel strip enters the dry ice spray cleaning chamber. Dry ice particles with an average particle size of 80 μm are sprayed and cleaned simultaneously on the upper and lower surfaces of the steel strip at a compressed air pressure of 1.2 MPa and an incident angle of 60°. When the dry ice particles come into contact with the high-temperature steel strip surface, they sublimate instantly, generating a violent thermal shock and micro-explosion effect. At the same time, the physical collision of high-speed particles can effectively peel off the rolling oil, rust-preventive oil and slight oxide layer on the surface of the steel strip. (2) Vacuum deposition of zinc-based thin films: The pretreated steel strip is directly fed into the continuous vacuum coating system. Before deposition, the deposition chamber is evacuated to a basic vacuum level of 5.0 × 10⁻⁶. -3 Pa; During the deposition process, the temperature of the steel strip was kept stable at 150℃; Pulsed magnetron sputtering was used for deposition, with a dual-target co-sputtering system: one was a high-purity (≥99.99%) pure zinc planar target, and the other was a zinc-magnesium alloy rotating target with a magnesium content of 4.0 wt%. The sputtering gas was high-purity argon (≥99.999%), and the working pressure was maintained at 0.3 Pa. The pulse power of the pure zinc target was set to 8 kW, the pulse power of the zinc-magnesium alloy target was set to 6 kW, and the pulse frequency was set to 50 kHz. By adjusting the feed rate of the steel strip to 3 m / min, a dense, uniform, and continuous zinc-based alloy film was deposited on both sides of the steel strip, and the resulting film thickness was 2.0 μm. (3) Post-treatment: Add deionized water and ethanol at a volume ratio of 1:4; slowly add glacial acetic acid while stirring at 300 rpm to adjust the pH of the mixed solution to 4.5; while stirring, slowly add silane coupling agent KH550 at a volume ratio of 4% of the total mass of the mixed solution; continue stirring to allow it to fully hydrolyze for 35 minutes to form a clear and transparent hydrolysate; add anatase nano-titanium dioxide powder with an average particle size of 30 nm at a volume ratio of 2% of the total mass of the aforementioned liquid, and slowly add it to the hydrolysate under high-speed shear at 5000 rpm; subsequently, add polyethylene glycol-400 (PEG-400) dispersant at a volume ratio of 0.3% of the nano-titanium dioxide powder; transfer the mixture to an ultrasonic dispersion device and ultrasonically disperse it at 400W power for 35 minutes to obtain the final product. The steel strip with the zinc-based thin film deposited is first rinsed with two deionized water sprays and dried. Then, the steel strip enters a precision roll coating machine and uses a single-sided transfer roll coating method to uniformly coat the surface of the steel strip with the nanocomposite passivation liquid prepared above. The coated steel strip is immediately put into a hot air circulating curing oven and baked at 130°C for 15 seconds. After curing, a nanocomposite passivation film is formed on the surface of the steel strip. The dry film thickness is 80 nm, and finally, galvanized steel strip is obtained.
[0021] Example 2 This embodiment provides a processing technology for galvanized steel strip, the steps of which include: (1) Physical pretreatment: The cold-rolled steel strip with a width of 1250mm and a thickness of 0.8mm is continuously passed through the preheating furnace. The surface temperature of the steel strip is precisely controlled at 320℃ by a combination of induction heating and hot air circulation heating. Then, the steel strip enters the dry ice spray cleaning chamber. Dry ice particles with an average particle size of 20μ0 are sprayed and cleaned on the surface of the steel strip under a compressed air pressure of 0.5MPa. When the dry ice particles come into contact with the high-temperature steel strip surface, they sublimate instantly, generating a violent thermal shock and micro-explosion effect. At the same time, the physical collision of high-speed particles can effectively peel off the rolling oil, rust-preventive oil and slight oxide layer on the surface of the steel strip. (2) Vacuum deposition of zinc-based thin films: The pretreated steel strip is directly fed into the continuous vacuum coating system. Before deposition, the deposition chamber is evacuated to a basic vacuum level of 5.0 × 10⁻⁶. -2 Pa; During the deposition process, the temperature of the steel strip was kept stable at 100℃; Pulsed magnetron sputtering was used for deposition, with a dual-target co-sputtering system: one target was a high-purity (≥99.99%) pure zinc planar target, and the other was a zinc-magnesium alloy rotating target with a magnesium content of 3wt%. The sputtering gas was high-purity argon (≥99.999%), and the working pressure was maintained at 0.3 Pa. By adjusting the steel strip speed to 3 m / min, a dense, uniform, and continuous zinc-based alloy film was deposited on both sides of the steel strip, with a film thickness of 2.0 μm. (3) Post-treatment: Add deionized water and ethanol at a volume ratio of 1:5; under stirring, slowly add glacial acetic acid to adjust the pH of the mixed solution to 4.0; while stirring, slowly add silane coupling agent KH550 at a volume ratio of 3% of the total mass of the mixed solution; continue stirring to allow it to fully hydrolyze for 30 minutes to form a clear and transparent hydrolysate; add anatase nano-titanium dioxide powder with an average particle size of 20 nm at a volume ratio of 1% of the total mass of the aforementioned liquid, and slowly add it to the hydrolysate under high-speed shear; subsequently, add polyethylene glycol-400 (PEG-400) dispersant at a volume ratio of 0.1% of the nano-titanium dioxide powder; transfer the mixture to an ultrasonic dispersion device and ultrasonically disperse for 30 minutes to obtain the final product. The steel strip with the zinc-based thin film deposited is first rinsed with two deionized water sprays and dried. Then, the nanocomposite passivation liquid prepared above is uniformly coated on the surface of the steel strip. The coated steel strip is immediately heated and cured by baking at 120°C for 20 seconds. After curing, a nanocomposite passivation film is formed on the surface of the steel strip. The dry film thickness is 80 nm, and finally, galvanized steel strip is obtained.
[0022] Example 3 This embodiment provides a processing technology for galvanized steel strip, the steps of which include: (1) Physical pretreatment: The cold-rolled steel strip with a width of 1250 mm and a thickness of 0.8 mm is continuously passed through the preheating furnace. The surface temperature of the steel strip is precisely controlled at 250℃ by a combination of induction heating and hot air circulation heating. Then, the steel strip enters the dry ice spray cleaning chamber. Dry ice particles with an average particle size of 150 μ5 are sprayed and cleaned on the surface of the steel strip under a compressed air pressure of 2.0 MPa. When the dry ice particles come into contact with the high-temperature steel strip surface, they sublimate instantly, generating a violent thermal shock and micro-explosion effect. At the same time, the physical collision of high-speed particles can effectively peel off the rolling oil, rust-preventive oil and slight oxide layer on the surface of the steel strip. (2) Vacuum deposition of zinc-based thin films: The pretreated steel strip is directly fed into the continuous vacuum coating system. Before deposition, the deposition chamber is evacuated to a basic vacuum level of 1.0 × 10⁻⁶. -3 Pa; During the deposition process, the temperature of the steel strip was kept stable at 180℃; Pulsed magnetron sputtering was used for deposition, with a dual-target co-sputtering system: one was a high-purity (≥99.99%) pure zinc planar target, and the other was a zinc-magnesium alloy rotating target with a magnesium content of 5.0 wt%; the sputtering gas was high-purity argon (≥99.999%), and the working pressure was maintained at 0.3 Pa; by adjusting the steel strip speed to 3 m / min, a dense, uniform, and continuous zinc-based alloy film was deposited on both sides of the steel strip, and the resulting film thickness was 2.0 μm. (3) Post-treatment: Add deionized water and anhydrous ethanol at a volume ratio of 1:3; under stirring, slowly add glacial acetic acid to adjust the pH of the mixed solution to 5.0; while stirring, slowly add silane coupling agent KH550, the amount of which is 5% of the total mass of the mixed solution; continue stirring to allow it to fully hydrolyze for 40 minutes to form a clear and transparent hydrolysate; add anatase nano-titanium dioxide powder with an average particle size of 40 nm, the amount of which is 3% of the total mass of the aforementioned liquid, and slowly add it to the hydrolysate under high-speed shear; subsequently, add polyethylene glycol-400 (PEG-400) dispersant accounting for 0.5% of the mass of the nano-titanium dioxide powder; transfer the mixture to an ultrasonic dispersion device and ultrasonically disperse for 40 minutes to obtain the final product. The steel strip with the zinc-based thin film deposited is first rinsed with two deionized water sprays and dried. Then, the nanocomposite passivation solution prepared above is uniformly coated on the surface of the steel strip. The coated steel strip is immediately heated and cured by baking at 140°C for 10 seconds. After curing, a nanocomposite passivation film is formed on the surface of the steel strip. The dry film thickness is 80 nm, and finally, galvanized steel strip is obtained.
[0023] Comparative Example 1 The difference between this comparative example and Example 1 is that step (1) of Example 1 is omitted, and the cold-rolled steel strip is sequentially passed through an alkaline degreasing tank (sodium hydroxide solution, 50°C, 3 minutes), a water rinsing tank, an acid pickling tank (hydrochloric acid solution, 10 wt%, room temperature, 1 minute), a water rinsing tank, and hot air drying; the subsequent steps (2) vacuum deposition and (3) post-treatment are exactly the same as in Example 1.
[0024] Comparative Example 2 The difference between this comparative example and Example 1 is that the steel strip is not preheated in step (1), and is cleaned by dry ice spray at 25°C. The other steps are the same as in Example 1.
[0025] Comparative Example 3 The difference between this comparative example and Example 1 is that only a pure zinc target is used for pulsed magnetron sputtering in step (2), and no zinc-magnesium alloy target is used; the coating thickness is made to 2.0 μm by adjusting the power and speed; the other steps are the same as in Example 1.
[0026] Comparative Example 4 The difference between this comparative example and Example 1 is that the temperature of the steel strip is maintained at 80°C during the deposition process in step (2).
[0027] Comparative Example 5 The difference between this comparative example and Example 1 is that the temperature of the steel strip is maintained at 200°C during the deposition process in step (2).
[0028] Comparative Example 6 The difference between this comparative example and Example 1 is that the entire step (3) is omitted, and the finished galvanized steel strip is directly obtained after vacuum deposition of zinc-magnesium alloy film in step (2).
[0029] Comparative Example 7 The difference between this comparative example and Example 1 is that in step (3), no nano titanium dioxide powder is added to the passivation solution, only a silane coupling agent KH550 hydrolysate (pH=4.5, addition amount 4.0%) is prepared, and no dispersant is added; the subsequent coating and curing process is the same as in Example 1.
[0030] Test Example 1: The galvanized steel strips prepared in Examples 1-3 and Comparative Examples 1-7 were subjected to the following tests: Coating adhesion: Tested according to GB / T 9286-2021 "Paints and Varnishes Cross-cut Test" standard; Bending performance: Tested in accordance with GB / T 232-2024 "Metallic Materials - Test Method for Bending" standard; Resistance to neutral salt spray: According to GB / T 10125-2021 "Artificial Atmosphere Corrosion Test Salt Spray Test" standard, the NaCl solution mass fraction is 5%, the chamber temperature is 35℃, continuous spraying is performed, the sample is placed at an angle of 20° to the vertical direction, and the time when the first white rust appears and the red rust area reaches 5% are recorded. Salt water immersion resistance: According to ISO 2812-2-2010 "Determination of resistance to liquids of coatings and varnishes - Part 2: Immersion method", the sample is completely immersed in a 3.5% NaCl solution at a temperature of 25°C. The solution is changed weekly, and the test cycle is 28 days. The surface condition of the coating is observed. Passivation film abrasion resistance: The test was conducted in accordance with ASTM D4060-07 "Standard test method for determining the abrasion resistance of organic coatings by a Tabel abrasion tester". A CS-10 abrasion wheel was used, with a load of 500g and a rotation speed of 60r / min. The number of abrasions that wore through the passivation film and exposed the zinc layer was recorded. The results are shown in Table 1 below: Table 1
[0031] Based on the foregoing, it is clear that Comparative Example 1, which uses traditional "alkali washing-acid washing" chemical pretreatment instead of dry ice physical cleaning, resulted in a product with performance significantly inferior to that of Example 1. Chemical residues and uneven corrosion led to decreased coating adhesion and a significant reduction in corrosion resistance. This indicates that the chemical-free and wastewater-free dry ice physical cleaning process used in this invention is a key prerequisite for obtaining a clean, active surface, thereby achieving excellent coating adhesion and corrosion resistance.
[0032] Comparative Example 2, where preheating was omitted and dry ice cleaning was performed directly at room temperature, showed a significant decrease in adhesion, corrosion resistance, and abrasion resistance. This indicates that the combination of high-temperature heating and dry ice blasting is crucial. Heating reduces grease viscosity and weakens the adhesion of the oxide layer, which, combined with the thermal shock effect generated by dry ice impact, is a necessary condition for achieving deep cleaning and surface activation.
[0033] Comparative Example 3 used a pure zinc target instead of a zinc-magnesium alloy target for co-sputtering, and the resulting coating exhibited significantly lower corrosion resistance (especially red rust time) than that of Example 1. This indicates that introducing an appropriate amount of magnesium into the coating (forming a Zn-Mg alloy) can significantly improve its long-term corrosion resistance by optimizing the coating's microstructure and sacrificial anode protection mechanism, which is one of the core innovations of this invention.
[0034] Comparative Example 4: The temperature of the substrate with coating is 80°C, which is lower than the lower limit of 100°C of the present invention. The adhesion, density and corrosion resistance of the coating are not ideal. Maintaining a suitable steel strip temperature is a necessary condition to ensure that the plating atoms have enough energy to migrate on the surface and form a dense, uniform and firmly bonded coating.
[0035] Comparative Example 5: The temperature of the coated substrate is 200°C, which is higher than the upper limit of 180°C of the present invention. This causes some elements to volatilize, the coating may be over-oxidized or stress may be generated, resulting in a decrease in bending performance and long-term corrosion resistance. The temperature range proposed in this invention is an optimized selection after considering coating quality, adhesion, production efficiency and energy consumption. Excessively high temperatures will have negative effects.
[0036] In Comparative Example 6, the corrosion resistance of the product deteriorated drastically after the passivation post-treatment step was removed; white and red rust appeared much earlier, and the product corroded rapidly in salt water immersion. This indicates that the nanocomposite passivation film not only provides an additional physical barrier but is also a core guarantee for effectively isolating the corrosive medium from contact with the zinc layer and delaying the electrochemical corrosion process; it is an indispensable last line of defense.
[0037] In Comparative Example 7, without the addition of nano-titanium dioxide, only a silane coupling agent was used in the passivation solution. The resulting passivation film exhibited severely insufficient wear resistance and a significant decrease in corrosion resistance. This indicates that nano-titanium dioxide particles play a crucial skeletal and reinforcing role in the passivation film, significantly improving its mechanical strength, wear resistance, and barrier effect. It is a key component for achieving high-performance passivation films.
[0038] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A processing method for galvanized steel strip, characterized by the following steps: include: S1. Physical pretreatment: Physical cleaning methods are used to remove grease and oxide layer from the surface of the steel strip; S2, Vacuum deposition of zinc-based thin film: In a vacuum environment, a continuous zinc-based thin film is formed on the surface of the steel strip after step S1 by vapor deposition. S3. Post-treatment: The galvanized steel strip is subjected to nano-composite passivation treatment with passivation solution to obtain galvanized steel strip.
2. The processing technology for galvanized steel strip according to claim 1, characterized in that, The physical pretreatment described in step S1 is as follows: the surface of the steel strip is heated to 250-320°C, and dry ice particles with an average particle size of 20-150μm are sprayed onto the heated steel strip surface under a pressure of 0.5-2.0MPa to remove contaminants by thermal shock and physical collision.
3. The processing technology for galvanized steel strip according to claim 1, characterized in that, In step S2, the vapor deposition method is pulsed magnetron sputtering; the vacuum level of the vacuum environment is no higher than 5.0 × 10⁻⁶. -2 Pa; During the vapor deposition, the steel strip temperature is maintained at 100-180℃.
4. The processing technology for galvanized steel strip according to claim 3, characterized in that, In step S2, the sputtering target used in the pulsed magnetron sputtering includes one or both of pure zinc target and zinc-magnesium alloy target.
5. The processing technology for galvanized steel strip according to claim 4, characterized in that, When the sputtering target used in the pulsed magnetron sputtering includes a zinc-magnesium alloy target, the mass percentage of magnesium in the zinc-magnesium alloy target is 3%-5%.
6. The processing technology for galvanized steel strip according to claim 1, characterized in that, In step S3, the passivation solution is prepared by: mixing deionized water and ethanol, adjusting the pH to 4.0-5.0 with acetic acid; adding silane coupling agent KH550 under stirring, and hydrolyzing for 30-40 minutes; then adding nano titanium dioxide powder and dispersant polyethylene glycol, and ultrasonically dispersing for 30-40 minutes to obtain the solution.
7. The processing technology for galvanized steel strip according to claim 6, characterized in that, The volume ratio of deionized water to ethanol is 1:3-1:5; the amount of silane coupling agent KH550 added accounts for 3%-5% of the total mass of the mixed solution; the amount of nano-titanium dioxide powder added accounts for 1%-3% of the total mass of the liquid; and the amount of polyethylene glycol added accounts for 0.1%-0.5% of the mass of nano-titanium dioxide powder.
8. The processing technology for galvanized steel strip according to claim 6, characterized in that, The average particle size of the nano-titanium dioxide powder is 20-40 nm.
9. The processing technology for galvanized steel strip according to claim 1, characterized in that, The passivation treatment step includes: rinsing the galvanized steel strip with deionized water, applying a passivation solution to the cleaned steel strip surface to form a wet film, and obtaining a steel strip coated with a wet film; heating and curing the steel strip coated with the wet film to form a nanocomposite passivation film; the thickness of the nanocomposite passivation film is 50-100 nm.
10. The processing technology for galvanized steel strip according to claim 9, characterized in that, The heating and curing step involves baking at 120-140℃ for 10-20 seconds.