A compound corrosion inhibitor for continuous metal coil and its treatment process

Abstract

The present invention discloses a compound corrosion inhibitor for continuous metal coils and a treatment process thereof, and relates to the field of corrosion inhibitors and treatment technologies. The corrosion inhibitor consists of an adsorption slow-release system solution and an induced film-forming system solution, and the surface of the metal coil is treated step by step in independent process tanks. The adsorption slow-release system contains a main corrosion inhibitor, an auxiliary corrosion inhibitor, an inhibitor and a surfactant, and the induced film-forming system contains a metal salt and a complexing control agent, which are used under set pH and concentration conditions respectively. The present invention uses a pre-adsorption system to carry out complexation coverage on the active sites of the metal surface, significantly inhibiting the initial corrosion reaction; the induced film-forming system generates a dense and stable inorganic film layer on this basis, thereby improving the interface impedance and corrosion resistance. By optimizing the compounding ratio, the synergistic effect of the components is achieved, and the structural integrity and protective performance of the film layer are improved; the double-tank step-by-step treatment is adopted to avoid component interference and enhance the continuity and stability of the film layer.

Description

Technical Field

[0001] The present invention relates to the field of corrosion inhibitors and treatment technologies, and in particular to a compound corrosion inhibitor for continuous metal coils and a treatment process thereof. Background Art

[0002] With the advancement of industrial lightweighting and green manufacturing trends, aluminum and its alloys have been widely used in multiple industrial fields such as aerospace, automobile manufacturing, rail transportation, and electronic products due to their excellent specific strength, corrosion resistance, and recyclability. In particular, they play an important role in the field of continuous metal coil production and surface treatment. Aluminum alloys are considered ideal structural and coating materials due to their natural passivation ability. However, in corrosive environments with halide ions such as chloride ions, their native oxide film is easily destroyed, and rapid pitting and expansion occur after fresh metal is exposed, seriously affecting their service life and interfacial stability, especially in humid or high-salt environments. Therefore, the development of efficient and environmentally friendly corrosion inhibitor systems and their continuous treatment processes is of great significance for improving the protection level of aluminum alloy coils.

[0003] Currently, surface protection methods used for aluminum alloys include anodizing, phosphating, chromate passivation, organic / inorganic composite coatings, and corrosion inhibitor solution treatment. Among them, the traditional chromate system has excellent corrosion resistance and film-forming ability, but it poses a significant environmental risk. Although anodizing can form a dense film layer, it has a long process cycle, high energy consumption, and is difficult to adapt to high-speed continuous processing systems. Organic or inorganic corrosion inhibitors have been widely studied for their environmental friendliness and process simplicity, but they generally have the following technical problems: First, existing corrosion inhibitors are mainly single-component, lacking the ability to directional complex the aluminum alloy surface, resulting in low adsorption efficiency, uneven film coverage, and inability to effectively seal micropores and grain boundary sites. Second, some corrosion inhibition films have loose structures or many defects, poor resistance to chloride ion penetration, and pitting corrosion easily extends under the film, leading to localized failure. Third, in multi-component coexisting systems, competitive adsorption and deposition interference between corrosion inhibitors and film-forming ions often occur, affecting the integrity of the film layer and functional synergy. In addition, existing industrial applications mostly adopt a single-tank integrated processing mode, which makes it difficult to effectively realize the functional division of adsorption components and film-forming components, resulting in a decrease in film-forming efficiency and fluctuations in film quality, which restricts the engineering adaptability and stability of aluminum alloy coil corrosion inhibition technology.

[0004] Therefore, there is an urgent need to develop a composite corrosion inhibition and protection system suitable for the continuous processing of aluminum alloy coils. This system should be able to quickly form a multi-component synergistic adsorption layer on the metal surface, preferentially blocking active points and inhibiting the expansion of initial pitting corrosion. On this basis, it should induce the deposition of a dense, highly bonded conversion film layer, thereby increasing interfacial impedance and inhibiting chloride ion penetration pathways. At the same time, a separate tank process design should be used to achieve functional separation of adsorption and film formation, avoiding interference between components and improving film integrity and uniformity. This solution should be environmentally friendly, highly controllable, and compatible with industrial continuous processing cycles, effectively improving the electrochemical stability and medium- and long-term corrosion protection capabilities of aluminum alloy coils. Summary of the Invention

[0005] The technical concept of the present invention is based on the green corrosion inhibitor design concept and the industrial continuous processing path optimization strategy. It breaks through the problems of weak corrosion inhibition ability of a single component, poor film density and insufficient continuous process compatibility in the existing corrosion inhibition system, and provides a high-efficiency composite corrosion inhibition and protection system constructed through the synergistic effect of the organic adsorption-inorganic film formation dual mechanism.

[0006] The specific plan is as follows:

[0007] A compound corrosion inhibitor for continuous metal coils, the corrosion inhibitor being prepared from an adsorption slow-release system solution and an induced film-forming system solution:

[0008] The adsorption slow-release system solution includes the following components:

[0009] The main corrosion inhibitor is a mixture of sodium glutamate and sodium glycine with a concentration of 0.06-0.2 mol / L

[0010] Auxiliary corrosion inhibitor, concentration is 0.005-0.05mol / L

[0011] Inhibitor, concentration 0.001-0.02 mol / L

[0012] Surfactant, concentration 0.001-0.01 mol / L

[0013] The rest is deionized water, and the pH of the solution is adjusted to 7.0-7.5;

[0014] The induced film-forming system solution includes the following components:

[0015] Potassium zirconate, concentration 0.005-0.015 mol / L

[0016] Complexation control agent, concentration is 0.001-0.01mol / L

[0017] The rest was deionized water, and the pH was adjusted to 4.0-5.0.

[0018] Preferably, the adsorption slow-release system solution and the induced film-forming system solution are sequentially applied to the first tank and the second tank during the continuous treatment of the metal coil to form an organic-inorganic synergistic composite corrosion inhibition film layer.

[0019] Preferably, the auxiliary corrosion inhibitor is one of sodium citrate, sodium malate, and sodium hypophosphite, which is used to further adjust the density of complexing sites and the capture ability of metal ions.

[0020] Preferably, the inhibitor is one of benzotriazole, EDTA, and sodium tripolyphosphate, which is used to block the anodic reaction or chloride ion corrosion path and to improve the adsorption uniformity and the wettability of the coil surface.

[0021] Preferably, the surfactant is one of sodium dodecylsulfonate, sodium dodecylbenzenesulfonate, and cocamidopropyl betaine, to ensure that the amino acid corrosion inhibitor can fully exert its function in a stable complex adsorption state.

[0022] Preferably, the molar ratio of sodium glutamate to sodium glycine is 2:1-5:1.

[0023] The present invention also provides a composite corrosion inhibitor treatment process for continuous metal coils, comprising the following steps:

[0024] (1) Coil pretreatment: The metal coil is subjected to alkaline degreasing, acid neutralization and deionized water rinsing in sequence;

[0025] (2) Treatment with adsorption and slow-release system solution: the coiled material output from step (1) enters the adsorption and slow-release system solution tank for immersion treatment;

[0026] (3) Inducing film formation with a film-forming system solution: the coiled material output from step (2) enters a film-forming system solution tank;

[0027] (4) The coiled material output from step (3) is dried with hot air, cooled and rolled up.

[0028] Preferably, the adsorption and slow-release system solution and the induced film-forming system solution in the corrosion inhibitor are prepared from the above raw materials.

[0029] Preferably, the treatment temperature in step (2) is 35-40°C and the soaking time is 60-90 seconds;

[0030] Preferably, the treatment temperature in step 3 is 40-50° C. and the treatment time is 30-60 seconds;

[0031] Preferably, the hot air temperature in step (4) is 80-90°C and the wind speed is 2-5m / s.

[0032] Preferably, the metal coil is any one of AA3003, AA5005, and AA6061 aluminum alloy coils.

[0033] Preferably, the coil is pretreated by degreasing, pickling and neutralizing the aluminum alloy coil and rinsing with deionized water in sequence. Preferably, the degreasing liquid is a mixture of 5wt% NaOH and 1wt% Na3PO4, the treatment temperature is 55°C, and the treatment time is 90 seconds; the pickling liquid is 1wt% HNO3, and the treatment time is 20 seconds to ensure a clean and active surface state.

[0034] Preferably, the coil thickness is 0.5-2 mm and the line speed is 3-8 m / min.

[0035] The technical solution provided by the present invention brings beneficial effects:

[0036] Improve initial corrosion blocking ability

[0037] This invention utilizes an amino acid adsorption corrosion inhibition system composed of sodium glutamate and sodium glycinate to achieve rapid complexation and adsorption on the aluminum alloy surface in the first treatment tank, forming a stable organic protective layer. This layer seals oxide film defects and microcracks in the initial corrosion phase, blocking the erosion pathways of corrosive ions such as Cl ions. In-situ corrosion observations demonstrate that this adsorption layer significantly reduces the number and reaction rate of initial electrochemically active areas, reduces the formation of corrosion products, and improves the integrity of the interface structure.

[0038] Constructing a dense and stable inorganic conversion film

[0039] In the second treatment tank, potassium zirconate and a complexing control agent synergistically induce the hydrolysis and deposition of Zr ions within the native oxide film and adsorption layer on the aluminum substrate, forming an inorganic conversion film primarily composed of Zr-O-Al or Zr-OC. This film has a continuous and dense structure, firmly bonded to the substrate, and significantly improves interfacial resistance and passivation performance. Electrochemical impedance spectroscopy testing reveals that the film resistance of the treated sample is higher than that of the comparative sample, while the interfacial capacitance is reduced, demonstrating the film's excellent corrosion resistance and stability.

[0040] Compound design enhances the synergistic effect of components

[0041] Optimizing the molar ratio of sodium glutamate to sodium glycinate enhances its uniform adsorption in micro-defect areas of the aluminum alloy oxide film and improves its interfacial reactivity with Zr ions. Synergistically acting with the potassium zirconate induction system, it forms an organic-inorganic multi-layer protective film. Polarization curves show that this combined ratio achieves the lowest corrosion current density and the highest inhibition efficiency, confirming the close correlation between the component ratio and film quality.

[0042] Dual-slot step-by-step processing to achieve interface function collaboration

[0043] Separate adsorption and film formation treatments avoid reaction interference between corrosion inhibition components, ensure the integrity of the adsorption layer, and enhance the directional deposition efficiency of Zr ions. This process results in a denser, less defective conversion film, effectively improving film continuity and thickness uniformity, enhancing coverage of Al ion dissolution and corrosion-inducing sites, and overall improving the protective performance of the film's functional structure.

[0044] Extend service life and environmental adaptability

[0045] The corrosion-inhibiting film constructed using this invention maintains excellent structural stability and durability in multiple cycles of humid heat or salt spray environments, without significant peeling, blistering, or precipitation of corrosion products. Compared to untreated samples, the film exhibits superior long-term density and surface uniformity, demonstrating its medium- and long-term protective effectiveness in the continuous production of aluminum alloy coils and in complex service environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 2 are potential polarization curves of the embodiments of the present invention and the comparative example;

[0047] Figure 2 Nyquist plots of the fitted data of the AC impedance spectra of the embodiments of the present invention and the comparative examples;

[0048] Figure 3 The fitted data-Bode plot of the AC impedance spectra of the embodiments of the present invention and the comparative example;

[0049] Figure 4 In-situ optical microscopy images of the blank sample of the present invention, (a) unetched; (b) etched for 1 minute; (c) etched for 5 minutes; (d) etched for 10 minutes; (e) etched for 15 minutes; (f) etched for 20 minutes;

[0050] Figure 5 In-situ optical microscopy images of Example 1 of the present invention; (a) unetched; (b) etched for 1 minute; (c) etched for 5 minutes; (d) etched for 10 minutes; (e) etched for 15 minutes; (f) etched for 20 minutes;

[0051] Figure 6 Graph showing the surface macroscopic morphology changes of the embodiments of the present invention and the comparative example. DETAILED DESCRIPTION

[0052] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the embodiments. Of course, the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0053] Example 1

[0054] 1. Materials and Equipment Preparation

[0055] Aluminum alloy coil: AA3003 hot-rolled aluminum alloy coil with a thickness of 1.0 mm, a coil width of 300 mm, and a line speed of 5 m / min.

[0056] Raw materials for corrosion inhibitor preparation:

[0057] Sodium glutamate (analytical grade, Aladdin)

[0058] Sodium glycinate (analytical grade)

[0059] Sodium citrate (as auxiliary corrosion inhibitor)

[0060] Benzotriazole (BTA, analytical grade)

[0061] Sodium dodecyl sulfate (SDS, surfactant)

[0062] Potassium zirconate (K2ZrF6, analytical grade)

[0063] Sodium gluconate (complexation control agent)

[0064] Deionized water (conductivity <1μS / cm)

[0065] 2. Corrosion Inhibitor Solution Configuration

[0066] The adsorption and sustained-release system solution (first tank) is configured as follows:

[0067] Sodium glutamate: 0.12 mol / L

[0068] Sodium glycinate: 0.03 mol / L (sodium glutamate: sodium glycinate = 4:1)

[0069] Sodium citrate: 0.01 mol / L

[0070] Benzotriazole (BTA): 0.005 mol / L

[0071] Sodium dodecyl sulfate: 0.005 mol / L

[0072] Adjust pH to 7.2 (fine-tune with NaOH or HCl)

[0073] The configuration of the induced film forming system solution (second tank) is as follows:

[0074] Potassium zirconate: 0.01 mol / L

[0075] Sodium gluconate: 0.005 mol / L

[0076] Adjust pH to 4.5 (fine-tune with acetic acid / sodium hydroxide buffer solution)

[0077] 3. Coil processing steps

[0078] Pretreatment section (continuous web cleaning system):

[0079] Alkaline degreasing solution: 5wt%NaOH+1wt%Na3PO4

[0080] Processing temperature: 55℃

[0081] Processing time: 90 seconds

[0082] Pickling solution: 1wt% HNO3

[0083] Processing time: 20 seconds

[0084] Neutralization and rinsing: Rinse twice with deionized water for 10 seconds each time to ensure that the pH returns to neutral and remove residual liquid

[0085] Adsorption and slow-release treatment section (first tank):

[0086] Bath temperature: 38°C

[0087] Soaking time: 90 seconds (continuous immersion)

[0088] Tank liquid circulation flow rate: 1 L / min, maintaining uniform concentration

[0089] Induced film forming treatment section (second tank):

[0090] Bath temperature: 45°C

[0091] Soaking time: 45 seconds

[0092] Maintain pH at 4.5 to prevent premature precipitation of Zr ions

[0093] Drying and winding section:

[0094] Hot air temperature: 85℃

[0095] Drying time: 3 minutes

[0096] Wind speed: 3.5 m / s

[0097] After the coil cools to room temperature, it is rolled up and packaged.

[0098] Example 2

[0099] The preparation was carried out according to the same preparation method as in Example 1, except that the main corrosion inhibitor was a mixture of sodium glutamate and sodium glycine with a concentration of 0.06 mol / L.

[0100] Example 3

[0101] The preparation was carried out according to the same preparation method as in Example 1, except that the main corrosion inhibitor was a mixture of sodium glutamate and sodium glycine with a concentration of 0.2 mol / L.

[0102] Example 4

[0103] The preparation method is the same as that of Example 1, except that the concentration of the auxiliary corrosion inhibitor is 0.005 mol / L.

[0104] Example 5

[0105] The preparation method is the same as that of Example 1, except that the concentration of the auxiliary corrosion inhibitor is 0.05 mol / L.

[0106] Example 6

[0107] The same preparation method as in Example 1 was used, except that the concentration of potassium zirconate was 0.005 mol / L.

[0108] Example 7

[0109] The same preparation method as in Example 1 was used, except that the concentration of potassium zirconate was 0.015 mol / L.

[0110] Example 8

[0111] The same preparation method as in Example 1 was used, except that the concentration of potassium zirconate was 0.01 mol / L.

[0112] Example 9

[0113] The preparation was carried out in the same manner as in Example 1, except that the molar ratio of sodium glutamate to sodium glycine was 2:1.

[0114] Example 10

[0115] The preparation was carried out in the same manner as in Example 1, except that the molar ratio of sodium glutamate to sodium glycine was 5:1.

[0116] Example 11

[0117] The preparation was carried out according to the same preparation method as in Example 1, except that the treatment temperature in step (2) was 35°C and the soaking time was 60 seconds; the treatment temperature in step 3 was 40°C and the treatment time was 30 seconds.

[0118] Example 12

[0119] The preparation was carried out according to the same preparation method as in Example 1, except that the treatment temperature in step (2) was 40°C and the soaking time was 90 seconds; the treatment temperature in step 3 was 50°C and the treatment time was 60 seconds.

[0120] Example 13

[0121] The preparation method is the same as that in Example 1, except that the metal coil is an AZ91 aluminum alloy coil.

[0122] Comparative Example 1

[0123] The preparation was carried out in the same manner as in Example 1, except that sodium glycinate was not added to the main corrosion inhibitor and the concentration remained unchanged.

[0124] Comparative Example 2

[0125] The preparation method is the same as that of Example 1, except that no auxiliary corrosion inhibitor is added.

[0126] Comparative Example 3

[0127] The preparation was carried out in the same manner as in Example 1, except that no film-forming induction system solution was used, and only the adsorption slow-release system solution was used.

[0128] Comparative Example 4

[0129] The preparation was carried out in the same manner as in Example 1, except that the adsorption and sustained-release system solution and the induced film-forming system solution were placed in the same liquid tank.

[0130] Comparative Example 5

[0131] The preparation method is the same as that of Example 1, except that the pH value of the adsorption sustained-release system solution and the induced film-forming system solution is not adjusted.

[0132] Comparative Example 6

[0133] The preparation was carried out in the same manner as in Example 1, except that the molar ratio of sodium glutamate to sodium glycine was 1:1.

[0134] Experimental test:

[0135] 1. Electrochemical corrosion test

[0136] The electrochemical corrosion performance test was carried out using a three-electrode system, in which the working electrode was the treated aluminum alloy coil sample (exposed area of ​​1 cm 2 ), the reference electrode was a saturated calomel electrode, the auxiliary electrode was a platinum electrode, and the test medium was a 3.5wt.% NaCl aqueous solution.

[0137] First, the open circuit potential test was performed, and after the potential stabilized, the potentiodynamic polarization test was performed with a scan rate of 1 mV / s and a potential range of open circuit potential ±350 mV; then the electrochemical impedance spectroscopy test was performed with a frequency range of 10 5 Hz to 10 -1Hz, and the disturbance voltage was 5mV. All tests were performed at room temperature, and all samples were tested at least three times in parallel, and the results were averaged.

[0138] 2. Original corrosion test

[0139] Aluminum alloy coil samples were etched with a 4 wt.% nitric acid solution for 3 seconds to reveal the grain boundary structure. An in-situ observation setup, consisting of a transparent observation cell and an optical microscope, recorded the corrosion behavior of the samples in real time in a 3.5 wt.% NaCl solution. Following the in-situ test, the samples were rinsed with anhydrous ethanol and dried. Corroded areas were located using backscattered electron scanning, and surface morphology was observed using a scanning electron microscope.

[0140] 3. Immersion test

[0141] Metal coil samples before and after treatment were cut into 1 cm × 1 cm test pieces according to industrial processes, cleaned with anhydrous ethanol, and dried before use. The samples were immersed in a 3.5 wt.% NaCl solution for 40 hours, with macroscopic changes in the sample surface recorded every 10 hours. After immersion, the sample surfaces were analyzed using scanning electron microscopy.

[0142] Table 1 Polarization curve fitting data

[0143]

[0144] according to Figure 1 From the polarization curve test results, it can be seen that Example 1 shows the best corrosion inhibition effect among all samples, with the lowest corrosion current density and the highest corrosion inhibition efficiency, indicating that a good synergistic effect is formed between the main corrosion inhibitor and the auxiliary corrosion inhibitor, surfactant and induced film-forming system in its formula. In contrast, although Examples 2 to 13 have been optimized or adjusted in parameters, they have failed to achieve the comprehensive corrosion inhibition performance of Example 1. This may be due to the interference of concentration deviation, molar ratio change or treatment conditions on the density and stability of the film layer, resulting in a slight decrease in the corrosion inhibition effect. Several comparative example samples all showed corrosion current densities significantly higher than those in the examples, among which the corrosion inhibition efficiency of Comparative Examples 1, 5 and 6 decreased particularly significantly, indicating that the lack of the main corrosion inhibitor, unadjusted pH or imbalanced ratios will significantly weaken the protective ability of the film layer. In addition, from the comparison of Comparative Example 3 and Comparative Example 4, it can be seen that the existence of the induced film-forming system alone is more advantageous than the mixed treatment of the two systems, indicating that staged treatment can more effectively promote the formation of a protective film. The overall results show that the dual-tank synergistic adsorption-film formation treatment method proposed in this invention, combined with amino acid main corrosion inhibitors, auxiliary ligands and Zr film formation system, significantly improves the passivation effect and corrosion resistance of the aluminum alloy surface, and has good engineering adaptability and promotion potential.

[0145] Table 2 Fitting data of AC impedance spectrum

[0146]

[0147] AC impedance spectroscopy results for the examples and comparative examples show that Example 1 exhibits the best performance, exhibiting the highest film resistance (Rf) and the lowest interfacial capacitance (CPEf), demonstrating the formation of a dense, stable, and high-impedance protective film on the aluminum alloy surface. This is primarily attributed to the synergistic effect between the optimal ratio of the primary inhibitor (sodium glutamate to sodium glycinate, 4:1) and the inductive film-forming system (potassium zirconate and sodium gluconate), which effectively induces the formation of a cross-linked Zr-rich passivation film. In other examples, when the primary inhibitor concentration or ratio is adjusted, or when the auxiliary component content is varied, the impedance performance generally decreases, indicating a reduction in the density or integrity of the protective film. Furthermore, the comparative example results show that the absence of key components (such as sodium glycinate, auxiliary inhibitors, or the inductive system) significantly reduces the film's impedance characteristics and overall corrosion inhibition efficiency, even degrading the system to levels close to those of a blank sample. This demonstrates the significant advantages of the multi-factor synergistic corrosion inhibition film-forming system proposed in this invention, with the presence of key components and the optimal parameter combination being crucial for ensuring its highly effective protective performance. Combined with the change in ηp value, the good correlation between impedance characteristics and corrosion inhibition efficiency can also be confirmed, verifying the significant improvement of the innovative system in inhibiting aluminum alloy corrosion.

[0148] By comparison Figure 4 (blank group) and Figure 5 (Example 1) The dynamic evolution of the in-situ corrosion test clearly shows that, in a 3.5 wt.% NaCl solution, the aluminum alloy coil sample without the addition of corrosion inhibitor exhibits a large number of concentrated bubbles at the initial corrosion stage (1 minute), primarily distributed at grain boundaries and in the α-Mg phase. Over time (up to 20 minutes), the number of bubbles increases significantly and their diameters expand, indicating sustained electrochemical reactions on the alloy surface and a vigorous corrosion process. In contrast, the Example 1 sample, under the same observation conditions, exhibits only sporadic bubbles after 5 minutes, which remain confined to a very small area. After 20 minutes, the surface morphology remains virtually identical to its initial state, with clear grain boundaries and no significant accumulation of corrosion products. Combined with the synergistic effect of the dual amino acid composite adsorption inhibition system and the potassium zirconate-induced film formation mechanism of the present invention, it can be inferred that the amino acid groups in the first trough preferentially complex with the metal surface to form a stable adsorption layer, blocking active sites and reducing the initial corrosion rate. In the second trough, Zr ions further react with the pre-adsorbed layer to form a dense cross-linked film, effectively blocking the Cl ion corrosion pathway. Therefore, the composite corrosion inhibitor system of the present invention significantly improves the corrosion resistance of aluminum alloy in a high-salt environment, verifying its significant advantages in inhibiting initial corrosion and long-term protection performance.

[0149] from Figure 6The comparison of the immersion effects at different time periods clearly shows that under the same 3.5 wt.% NaCl corrosion environment, the blank group and comparative examples 3 and 4 samples all show a significant increase in corrosion products, surface roughening and corrosion expansion over time, especially at 30h and 40h, the corrosion plaques have covered a large area, and some areas even have peeling and pitting morphology, indicating that their corrosion resistance is weak; while the surface change of the sample in Example 1 is minimal during the entire 40-hour immersion process, with only a small amount of dispersed corrosion points, good overall finish, and no obvious corrosion plaques or product coverage. Combining the sodium glutamate-sodium glycinate main corrosion inhibition system and potassium zirconate induced film construction mechanism used in Example 1, it is inferred that it first forms a high-density organic adsorption layer on the surface to inhibit the initial oxidation reaction, and then forms a dense inorganic conversion film through Zr ion complexation for dual protection, thereby effectively blocking the Cl ion erosion path and the electrochemical reaction activity of metal ions. In contrast, comparative examples 3 and 4 lack induced film construction or reasonable component ratios, resulting in discontinuous film protection and gradual corrosion expansion. Therefore, this figure verifies that the embodiment of the present invention can significantly improve the medium- and long-term corrosion resistance of aluminum alloy coils in a salt spray environment under the synergistic effect of slow-release adsorption and film formation.

[0150] The above description is only a preferred embodiment of the present invention and is 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 in the scope of protection of the present invention.

Claims

1. A compound corrosion inhibitor for continuous metal coils, characterized in that: The corrosion inhibitor consists of an adsorption slow-release system solution and an induced film-forming system solution: The adsorption slow-release system solution includes the following components: The main corrosion inhibitor is a mixture of sodium glutamate and sodium glycine with a concentration of 0.06-0.2 mol / L Auxiliary corrosion inhibitor, concentration is 0.005-0.05mol / L Inhibitor, concentration 0.001-0.02 mol / L Surfactant, concentration 0.001-0.01 mol / L The rest is deionized water, pH adjusted to 7.0-7.5; The induced film-forming system solution includes the following components: Potassium zirconate, concentration 0.005-0.015 mol / L Complexation control agent, concentration is 0.001-0.01mol / L The rest is deionized water, and the pH is adjusted to 4.0-5.0; The auxiliary corrosion inhibitor is one of sodium citrate, sodium malate and sodium hypophosphite; The inhibitor is one of benzotriazole, EDTA, and sodium tripolyphosphate; the surfactant is one of sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and cocamidopropyl betaine; The molar ratio of sodium glutamate to sodium glycine is 2:1-5:1; The adsorption slow-release system solution and the induced film-forming system solution are sequentially applied to the first tank and the second tank in the continuous processing process of the metal coil to form an organic-inorganic synergistic composite corrosion inhibition film layer.

2. A composite corrosion inhibitor treatment process for continuous metal coils, characterized in that: The steps include: (1) Coil pretreatment: The metal coil is subjected to alkaline degreasing, acid neutralization and deionized water rinsing in sequence; (2) Treatment with adsorption and slow-release system solution: the coiled material output from step (1) enters the adsorption and slow-release system solution tank for immersion treatment; (3) Inducing film formation with a film-forming system solution: the coiled material output from step (2) enters a film-forming system solution tank; (4) hot air drying, cooling and winding the coiled material output from step (3); The components of the adsorption slow-release system solution and the induction film-forming system solution in the corrosion inhibitor are as shown in the components of the adsorption slow-release system solution and the induction film-forming system solution according to claim 1; The treatment temperature of step (2) is 35-40°C and the soaking time is 60-90 seconds; The treatment temperature of step (3) is 40-50°C and the treatment time is 30-60 seconds; The hot air temperature in step (4) is 80-90° C., and the wind speed is 2-5 m / s.

3. The composite corrosion inhibitor treatment process for continuous metal coils according to claim 2, characterized in that: The metal coil is any one of AA3003, AA5005, and AA6061 aluminum alloy coils.

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