Corrosion inhibitor for zinc-aluminum-magnesium plated steel sheet, preparation method and composite protective film

Abstract

The application provides a kind of inhibitor for zinc-aluminum-magnesium plated steel sheet and preparation method, composite protective film, belongs to the field of metal surface treatment.The components of the inhibitor include: solute: 0.1%~10%, solvent 90%~99.9% by mass fraction;Among them, the chemical composition of the solute includes: thiazole corrosion inhibitor 30~50 parts, polyphosphate 30~50 parts, zinc salt 5~30 parts by mass fraction.The components of the inhibitor are reasonably designed, thiazole corrosion inhibitor is used as adsorption type corrosion inhibitor, polyphosphate and zinc salt are used to form precipitation type corrosion inhibitor, adsorption type corrosion inhibitor and precipitation type corrosion inhibitor are compounded, through the synergistic effect of adsorption type corrosion inhibitor and precipitation type corrosion inhibitor, adsorption type protective film and precipitation type protective film are formed, precipitation type protective film is partially filled in the molecular gap of the adsorption type protective film, and the composite protective film is more compact than the single protective film, thereby inhibiting the surface filamentous corrosion of the zinc-aluminum-magnesium plated steel sheet.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of metal surface treatment, in particular to an inhibitor for a zinc-aluminum-magnesium plated steel plate and a preparation method and a composite protective film. BACKGROUND

[0002] A zinc-based plating layer can effectively improve the corrosion resistance of a steel surface, especially after a small amount of aluminum and magnesium elements are added to the plating layer, because the addition of aluminum and magnesium elements can effectively refine the grains, and a multi-phase structure is formed in the plating layer, including a pure zinc phase, a Zn-MgZn2 binary eutectic phase, a Zn-MgZn2-Al ternary eutectic phase and the like, wherein MgZn2 has the lowest corrosion potential, and corrosion and dissolution occur preferentially as an anode, the dissolved MgZn2 phase supplies Mg 2+ reacts with the OH - generated by oxygen reduction to generate Mg(OH)2 preferentially, which can effectively alleviate the increase in pH and promote the generation of basic zinc salt, the corrosion product is dense and electronically insulating, and can effectively isolate the further invasion of corrosion factors, thereby providing better protection for the steel substrate, so that the zinc-aluminum-magnesium plating layer has more excellent corrosion resistance.

[0003] However, when the steel plate or the aluminum plate is used as a coated plate, because of the existence of the surface organic coating, when the coating has defects, erosive ions corrode the plating layer at the paint film damage position to cause local corrosion, and the oxygen concentration difference environment between the film and the outside world causes the corrosion to rapidly expand, and the filamentous corrosion phenomenon is found on the surfaces of various materials such as carbon steel, aluminum alloy, zinc-based plated steel plate and the like. As one of the most efficient and convenient corrosion protection methods in the current industrial field, the inhibitor is a chemical substance that can effectively slow down or prevent material corrosion in a low concentration in a corrosion medium, and has the advantages of simple operation, low cost and remarkable effect. The inhibitor is mainly divided into organic inhibitors and inorganic inhibitors, the organic inhibitor mainly includes organic compounds containing N, P and S heteroatoms, the lone pair electrons of which are easy to interact with the empty orbit of the metal surface to form an adsorption film and then play a corrosion inhibition role. The inorganic inhibitor mainly includes chromate, nitrite, molybdate, borate and phosphate, and the action mechanism is mainly to react on the metal surface to form a dense oxide film or a precipitate film. At present, the research on the inhibitor system for inhibiting filamentous corrosion mainly focuses on carbon steel, aluminum alloy and other materials, and there are few reports on the inhibitor for zinc-aluminum-magnesium plating layer materials. Therefore, it is of great significance to develop an inhibitor system for inhibiting the filamentous corrosion of a zinc-aluminum-magnesium plating layer. SUMMARY

[0004] The application provides an inhibitor for a zinc-aluminum-magnesium plated steel plate and a preparation method and a composite protective film, so as to solve the technical problem of how to inhibit the filamentous corrosion on the surface of the zinc-aluminum-magnesium plated steel plate.

[0005] In a first aspect, the application provides an inhibitor for a zinc-aluminum-magnesium plated steel sheet, the inhibitor comprising, in mass fraction, 0.1-10% of a solute and 90-99.9% of a solvent, wherein the solute comprises, in mass fraction, 30-50 parts of a thiazole inhibitor, 30-50 parts of a polyphosphate, and 5-30 parts of a zinc salt.

[0006] Optionally, the solvent is a mixture of ethanol and deionized water, and the volume ratio of the ethanol to the deionized water is 1:5-1:20.

[0007] Optionally, the thiazole inhibitor comprises one or more of benzothiazole, mercaptobenzothiazole, benzothiadiazole, sodium mercaptobenzothiazole, and sodium mercaptobenzothiazole.

[0008] Optionally, the polyphosphate comprises one or more of sodium tripolyphosphate and sodium hexametaphosphate.

[0009] Optionally, the zinc salt comprises one or more of zinc chloride, zinc nitrate, and zinc sulfate.

[0010] Optionally, the inhibitor comprises, in mass fraction, 1-5% of a solute and 95-99% of a solvent, wherein the solute comprises, in mass fraction, 40-50 parts of a thiazole inhibitor, 40-50 parts of a polyphosphate, and 5-15 parts of a zinc salt, and the solvent is a mixture of ethanol and deionized water, and the volume ratio of the ethanol to the deionized water is 1:5.

[0011] In a second aspect, the application provides a preparation method of the inhibitor described in any one of the first aspect or the embodiments thereof, the method comprising:

[0012] dissolving the thiazole inhibitor in ethanol and performing first stirring to obtain a first solution;

[0013] dissolving the polyphosphate in deionized water and performing second stirring to obtain a second solution;

[0014] adding the second solution to the first solution, then adding the zinc salt, and performing third stirring to obtain the inhibitor.

[0015] Optionally, the first stirring, the second stirring, and the third stirring are all performed at a temperature of 20-50°C, and the first stirring, the second stirring, and the third stirring are all performed for 30-60 minutes.

[0016] In a third aspect, the application provides a composite protective film formed by adsorption and precipitation of the inhibitor described in any one of the first aspect or the embodiments thereof, and the composite protective film formed by the inhibitor has an inhibition rate of filamentous corrosion of a zinc-aluminum-magnesium plated steel sheet of ≥70%.

[0017] Optionally, the composite protective film comprises an adsorption type protective film and a precipitation type protective film, and the precipitation type protective film is partially filled in the molecular gap of the adsorption type protective film.

[0018] Compared with the prior art, the above technical solution provided by the embodiments of the present application has the following advantages:

[0019] The corrosion inhibitor for zinc-aluminum-magnesium plated steel sheet provided by the embodiments of the present application comprises, by mass fraction, 0.1-10% of solute and 90-99.9% of solvent, wherein the chemical components of the solute, by mass fraction, comprise 30-50 parts of thiazole corrosion inhibitor, 30-50 parts of polyphosphate and 5-30 parts of zinc salt. The components of the corrosion inhibitor are reasonably designed, the thiazole corrosion inhibitor is used as the adsorption type corrosion inhibitor, the polyphosphate and the zinc salt are used to form the precipitation type corrosion inhibitor, the adsorption type corrosion inhibitor and the precipitation type corrosion inhibitor are compounded, the adsorption type protective film and the precipitation type protective film are formed through the synergistic effect of the adsorption type corrosion inhibitor and the precipitation type corrosion inhibitor, the precipitation type protective film is partially filled in the molecular gap of the adsorption type protective film, the composite protective film is more compact than the single protective film, and thus the corrosion inhibition effect can be greatly improved, the corrosion occurrence time can be prolonged, the corrosion rate can be slowed down, and the filamentous corrosion on the surface of the zinc-aluminum-magnesium plated steel sheet is inhibited. BRIEF DESCRIPTION OF DRAWINGS

[0020] The accompanying drawings, which are incorporated into and form a part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application.

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, for those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative labor.

[0022] Figure 1 The flowchart of the preparation method of the corrosion inhibitor for zinc-aluminum-magnesium plated steel sheet provided by the embodiments of the present application is shown. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0024] Various embodiments of the present application can exist in a range of forms; it should be understood that the description in a range form is merely for the convenience and brevity, and should not be understood as a hard limitation on the scope of the present application; therefore, it should be considered that the range described has been specifically disclosed all possible sub-ranges and single values within the range. For example, it should be considered that the range description from 1 to 6 has been specifically disclosed sub-ranges, such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., as well as single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. In addition, whenever a numerical range is indicated in this document, it refers to any cited number (fraction or integer) within the indicated range.

[0025] In addition, in the description of the present application, the terms "include", "contain" and the like mean "include but not limited to". In this document, relational terms such as "first" and "second" and the like are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that these entities or operations have any such actual relationship or order. In this document, "and / or" describes the association relationship of the associated objects, which means that there can be three kinds of relationships, for example, A and / or B can represent the cases of A alone, A and B together, and B alone. Where A and B can be singular or plural. In this document, "one or more" means one or more, and "multiple" means two or more. "At least one", "at least one of the following" or the like means any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can mean a, b, c, a-b (i.e. a and b), a-c, b-c, or a-b-c, where a, b, and c can be single or multiple.

[0026] Unless otherwise specifically stated, the various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0027] The present application provides a kind of inhibitor for zinc-aluminum-magnesium plated steel sheet, with mass fraction, the components of the inhibitor include: solute: 0.1%~10%, solvent 90%~99.9%;Wherein, with mass parts, the chemical composition of the solute includes: thiazole inhibitor 30 parts~50 parts, polyphosphate 30 parts~50 parts, zinc salt 5 parts~30 parts.

[0028] In some embodiments, the solvent is a mixed solution of ethanol and deionized water, and the volume ratio of the ethanol and deionized water is (1:5)~(1:20).

[0029] In some embodiments, the thiazole corrosion inhibitor includes one or more of benzothiazole, mercaptobenzotriazole, benzothiadiazole, sodium mercaptobenzotriazole, and sodium mercaptobenzothiazole.

[0030] In some embodiments, the polyphosphate salt includes one or more of sodium tripolyphosphate and sodium hexametaphosphate.

[0031] In some embodiments, the zinc salt includes one or more of zinc chloride, zinc nitrate, and zinc sulfate.

[0032] In the above embodiments, the mass fraction of the solute is controlled to be 0.1% to 10%, and the mass fraction of the solvent is controlled to be 90% to 99.9%. If the content of the solute is too low, a continuous and dense corrosion inhibitor film layer cannot be formed on the surface of the steel plate, and the corrosion inhibition efficiency is low. If the content of the solute is too high, the corrosion inhibition efficiency does not improve significantly after the corrosion inhibitor reaches the saturation adsorption amount, and the cost is increased. For example, the mass fraction of the solute in the corrosion inhibitor can be 0.1%, 1%, 2%, 3%, 5%, 7%, 9%, 10%, etc., and the mass fraction of the solvent can be 90%, 91%, 93%, 95%, 97%, 99%, 99.9%, etc.

[0033] In the above embodiments, it should be noted that the solute is composed of the thiazole corrosion inhibitor, the polyphosphate salt, and the zinc salt. The thiazole corrosion inhibitor is controlled to be 30 parts to 50 parts. The thiazole corrosion inhibitor has a benzene ring structure and N and S atoms with lone pair electrons. The benzene ring can increase the adsorption area of the corrosion inhibitor on the surface of the steel plate. The benzene group improves the hydrophobicity of the corrosion inhibitor, and the corrosion inhibitor is adsorbed on the surface of the steel plate to form a hydrophobic film with a large coverage area, thereby improving the corrosion inhibition effect. The N and S atoms can provide more adsorption sites. The lone pair electrons of the N and S atoms form strong adsorption with the surface of the steel plate through additional bonding, thereby blocking the direct contact between the corrosive medium and the surface of the steel plate and delaying corrosion. The polyphosphate salt is controlled to be 30 parts to 50 parts, and the zinc salt is controlled to be 5 parts to 30 parts. The polyphosphate salt has the ability to form a complex with metal ions such as Mg 2+ 2+ , Zn, etc. The polyphosphate salt can react with the metal elements in the zinc-aluminum-magnesium coating. The zinc salt provided in this embodiment has good water solubility. The zinc salt can supplement metal ions in the solution and form a dense zinc phosphate with the polyphosphate root, thereby forming a precipitated protective film, increasing the surface charge transfer resistance of the coating, and improving the corrosion resistance. On the other hand, the polyphosphate ion structure is relatively small, and can fill the gaps in the adsorption film of the thiazole corrosion inhibitor and other macromolecules. The mixed corrosion inhibitor film is more dense than the single corrosion inhibitor film. For example, the solute is composed of the following components. The thiazole corrosion inhibitor can be 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, etc. The polyphosphate salt can be 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, etc. The zinc salt can be 5 parts, 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, etc.

[0034] In the above embodiments, the volume ratio of ethanol and deionized water in the solvent is ethanol: deionized water = (1:5) to (1:20). If the ethanol content is too low, the thiazole corrosion inhibitor cannot be completely dissolved. If the ethanol content is too high, the solvent is easy to evaporate during preparation and stirring. For example, the volume ratio of ethanol and deionized water can be 1:5, 1:8, 1:10, 1:12, 1:15, 1:18, 1:20, etc.

[0035] In some embodiments, the components of the corrosion inhibitor include, by mass fraction: solute: 1% to 5%, solvent 95% to 99%; wherein the chemical composition of the solute includes, by mass fraction: thiazole corrosion inhibitor 40 parts to 50 parts, polyphosphate 40 parts to 50 parts, zinc salt 5 parts to 15 parts, and the solvent is a mixed solution of ethanol and deionized water, and the volume ratio of the ethanol and deionized water is 1:5.

[0036] Figure 1 A flowchart of a preparation method of a corrosion inhibitor for zinc-aluminum-magnesium plated steel sheet provided in the embodiments of the present application is shown.

[0037] See Figure 1 The present application provides a preparation method of a corrosion inhibitor, which comprises:

[0038] S1, dissolving a thiazole corrosion inhibitor in ethanol and performing first stirring to obtain a first solution;

[0039] S2, dissolving a polyphosphate in deionized water and performing second stirring to obtain a second solution;

[0040] S3, adding the second solution to the first solution, then adding a zinc salt, and performing third stirring to obtain a corrosion inhibitor.

[0041] In some embodiments, the temperature of the first stirring, the second stirring and the third stirring is 20°C to 50°C, and the time of the first stirring, the second stirring and the third stirring is 30min to 60min.

[0042] In the above embodiments, the temperature of the first stirring, the second stirring and the third stirring is 20-50°C. This is because if the stirring temperature is too low, the inhibitor adsorption and precipitation is slow, and a dense inhibitor film layer cannot be quickly formed on the surface of the steel plate; if the stirring temperature is too high, the organic molecules will be inactivated, and the inhibition efficiency will be reduced. The time of the first stirring, the second stirring and the third stirring is 30-60 min. This is because if the stirring time is too short, the inhibitor will not be mixed uniformly, resulting in uneven local adsorption / precipitation reaction; if the stirring time is too long, there is a possibility of complex reaction between the polyphosphate and the zinc salt in the inhibitor solution. Exemplarily, the temperature of the first stirring, the second stirring and the third stirring can be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, etc., and the time of the first stirring, the second stirring and the third stirring can be 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, etc.

[0043] The product prepared by the preparation method of the inhibitor is the above-mentioned inhibitor, and the chemical composition and microstructure of the inhibitor prepared by the preparation method of the inhibitor can refer to the above-mentioned embodiments. Since the preparation method of the inhibitor adopts part or all of the technical solutions of the inhibitor embodiments, it at least has all the beneficial effects brought by the technical solutions of the inhibitor embodiments, which will not be repeated here.

[0044] Based on one overall inventive concept, the present application provides a composite protective film formed by adsorption and precipitation reaction of an inhibitor, and the composite protective film formed by the inhibitor has an inhibition rate of filamentous corrosion of zinc-aluminum-magnesium steel plate of ≥70%.

[0045] In some embodiments, the composite protective film comprises an adsorption-type protective film and a precipitation-type protective film, and the precipitation-type protective film is partially filled in the molecular voids of the adsorption-type protective film.

[0046] The present application compounding the adsorption-type inhibitor and the precipitation-type inhibitor, and through the synergistic effect of the adsorption-type inhibitor and the precipitation-type inhibitor, an adsorption-type protective film and a precipitation-type protective film are formed, and the precipitation-type protective film is filled in the molecular voids of the adsorption-type protective film. In this way, the inhibition effect can be greatly improved, the corrosion occurrence time can be prolonged, and the corrosion rate can be slowed down.

[0047] The present application will be further described in conjunction with specific examples. It should be understood that these examples are only used to illustrate the present application and not to limit the scope of the present application. The experimental methods not specified in the following examples are generally determined according to the industry standards. If there is no corresponding industry standard, the general international standards, conventional conditions, or the conditions suggested by the manufacturers are followed.

[0048] Example 1

[0049] An inhibitor for zinc-aluminum-magnesium plated steel sheet, the inhibitor comprising a solute and a solvent, wherein the solute accounts for 0.2wt% of the inhibitor and the solvent accounts for 99.8wt% of the inhibitor; wherein the solute consists of the following components, each in parts by weight: benzothiazole 50 parts, sodium tripolyphosphate 40 parts, zinc chloride 10 parts; the solvent is a mixed solution of ethanol and deionized water, in a volume ratio of 1:5.

[0050] The preparation method comprises the following steps: (1) dissolving benzothiazole in ethanol accounting for 1 / 6 of the solvent to prepare a solution of a certain concentration, and stirring until completely dissolved; (2) dissolving sodium tripolyphosphate in deionized water accounting for 5 / 6 of the solvent to prepare a solution of a certain concentration, and stirring until completely dissolved; (3) slowly adding the solution obtained in (2) to the mixed solution obtained in (1), adding zinc chloride, and stirring until fully mixed. The stirring temperature is 25°C, and the stirring time is 60 min.

[0051] The inhibitor is added dropwise to the coating defect position, and test results show that the inhibitor has an inhibition rate of 70% on filamentous corrosion of zinc-aluminum-magnesium sheet.

[0052] Example 2

[0053] An inhibitor for zinc-aluminum-magnesium plated steel sheet, the inhibitor comprising a solute and a solvent, wherein the solute accounts for 5wt% of the inhibitor and the solvent accounts for 95wt% of the inhibitor; wherein the solute consists of the following components, each in parts by weight: mercaptobenzothiazole 50 parts, sodium hexametaphosphate 40 parts, zinc chloride 10 parts; the solvent is a mixed solution of ethanol and deionized water, in a volume ratio of 1:5.

[0054] The preparation method comprises the following steps: (1) dissolving mercaptobenzothiazole in ethanol accounting for 1 / 6 of the solvent to prepare a solution of a certain concentration, and stirring until completely dissolved; (2) dissolving sodium hexametaphosphate in deionized water accounting for 5 / 6 of the solvent to prepare a solution of a certain concentration, and stirring until completely dissolved; (3) slowly adding the solution obtained in (2) to the mixed solution obtained in (1), adding zinc chloride, and stirring until fully mixed. The stirring temperature is 25°C, and the stirring time is 30 min.

[0055] The inhibitor is added dropwise to the coating defect position, and test results show that the inhibitor has an inhibition rate of 90% on filamentous corrosion of zinc-aluminum-magnesium sheet.

[0056] Example 3

[0057] An inhibitor for zinc-aluminum-magnesium plated steel sheet, the inhibitor comprising a solute and a solvent, wherein the solute accounts for 0.5wt% of the inhibitor and the solvent accounts for 99.5wt% of the inhibitor; wherein the solute consists of the following components, each in parts by weight: mercaptobenzothiazole 45 parts, sodium tripolyphosphate 40 parts, zinc chloride 5 parts; the solvent is a mixed solution of ethanol and deionized water, in a volume ratio of 1:5.

[0058] The preparation method comprises the following steps: (1) dissolving mercaptobenzothiazole in ethanol with a solvent ratio of 1 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (2) dissolving sodium tripolyphosphate in deionized water with a solvent ratio of 5 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (3) slowly adding the solution obtained in (2) into the mixed solution obtained in (1), and adding zinc chloride, and stirring until fully mixed. The stirring temperature is 25 DEG C, and the stirring time is 30 min.

[0059] The inhibitor is added dropwise to the coating defect position, and test results show that the inhibitor has an inhibition rate of 80% on the filamentous corrosion of the zinc-aluminum-magnesium plate.

[0060] Example 4

[0061] An inhibitor for a zinc-aluminum-magnesium plated steel plate, the inhibitor comprising a solute and a solvent, wherein the solute accounts for 2 wt% of the inhibitor, and the solvent accounts for 98 wt% of the inhibitor; wherein the solute is composed of the following components, and each component is in parts by weight: benzothiadiazole 40 parts, sodium tripolyphosphate 50 parts, and zinc nitrate 10 parts; and the solvent is a mixed solution of ethanol and deionized water, and the volume ratio is 1:5.

[0062] The preparation method comprises the following steps: (1) dissolving benzothiadiazole in ethanol with a solvent ratio of 1 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (2) dissolving sodium tripolyphosphate in deionized water with a solvent ratio of 5 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (3) slowly adding the solution obtained in (2) into the mixed solution obtained in (1), and adding zinc nitrate, and stirring until fully mixed. The stirring temperature is 25 DEG C, and the stirring time is 30 min.

[0063] The inhibitor is added dropwise to the coating defect position, and test results show that the inhibitor has an inhibition rate of 88% on the filamentous corrosion of the zinc-aluminum-magnesium plate.

[0064] Example 5

[0065] An inhibitor for a zinc-aluminum-magnesium plated steel plate, the inhibitor comprising a solute and a solvent, wherein the solute accounts for 1 wt% of the inhibitor, and the solvent accounts for 99 wt% of the inhibitor; wherein the solute is composed of the following components, and each component is in parts by weight: mercaptobenzothiazole sodium 40 parts, sodium hexametaphosphate 50 parts, and zinc nitrate 10 parts; and the solvent is a mixed solution of ethanol and deionized water, and the volume ratio is 1:10.

[0066] The preparation method comprises the following steps: (1) dissolving mercaptobenzothiazole sodium in ethanol with a solvent ratio of 1 / 11 to prepare a solution with a certain concentration, and stirring until completely dissolved; (2) dissolving sodium tripolyphosphate in deionized water with a solvent ratio of 10 / 11 to prepare a solution with a certain concentration, and stirring until completely dissolved; (3) slowly adding the solution obtained in (2) into the mixed solution obtained in (1), and adding zinc nitrate, and stirring until fully mixed. The stirring temperature is 25 DEG C, and the stirring time is 30 min.

[0067] The inhibitor is added dropwise to the coating defect position, and test results show that the inhibitor has an inhibition rate of 84% on the filamentous corrosion of the zinc-aluminum-magnesium plate.

[0068] Example 6

[0069] The inhibitor for the zinc-aluminum-magnesium plated steel plate comprises a solute and a solvent, wherein the solute accounts for 2% of the inhibitor by weight, and the solvent accounts for 98% of the inhibitor by weight; the solute is composed of the following components, and each component is in parts by weight: 40 parts of mercaptobenzothiazole sodium, 50 parts of sodium tripolyphosphate, and 10 parts of zinc sulfate; and the solvent is a mixed solution of ethanol and deionized water with a volume ratio of 1:10.

[0070] The preparation method comprises the following steps: (1) dissolving mercaptobenzothiazole sodium in ethanol with a solvent ratio of 1 / 11 to prepare a solution with a certain concentration, and stirring until completely dissolved; (2) dissolving sodium tripolyphosphate in deionized water with a solvent ratio of 10 / 11 to prepare a solution with a certain concentration, and stirring until completely dissolved; (3) slowly adding the solution obtained in (2) into the mixed solution obtained in (1), and adding zinc nitrate, and stirring until fully mixed. The stirring temperature is 25 DEG C, and the stirring time is 30 min.

[0071] The inhibitor is added dropwise to the coating defect position, and test results show that the inhibitor has an inhibition rate of 86% on the filamentous corrosion of the zinc-aluminum-magnesium plate.

[0072] Example 7

[0073] The inhibitor for the zinc-aluminum-magnesium plated steel plate comprises a solute and a solvent, wherein the solute accounts for 2% of the inhibitor by weight, and the solvent accounts for 98% of the inhibitor by weight; the solute is composed of the following components, and each component is in parts by weight: 40 parts of mercaptobenzothiazole sodium, 50 parts of sodium tripolyphosphate, and 10 parts of zinc sulfate; and the solvent is a mixed solution of ethanol and deionized water with a volume ratio of 1:10.

[0074] The preparation method comprises the following steps: (1) dissolving mercaptobenzothiazole in ethanol with a solvent ratio of 1 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (2) dissolving sodium tripolyphosphate in deionized water with a solvent ratio of 5 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (3) slowly adding the solution obtained in (2) into the mixed solution obtained in (1), and adding zinc chloride, and stirring until fully mixed. The stirring temperature is 25 DEG C, and the stirring time is 30 min.

[0075] The inhibitor is added dropwise to the coating defect position, and test results show that the inhibitor has an inhibition rate of 89% on the filamentous corrosion of the zinc-aluminum-magnesium plate.

[0076] Example 8

[0077] An inhibitor for a zinc-aluminum-magnesium plated steel plate, the inhibitor comprising a solute and a solvent, wherein the solute accounts for 2 wt% of the inhibitor, and the solvent accounts for 98 wt% of the inhibitor; wherein the solute is composed of the following components, each in parts by weight: 45 parts of mercaptobenzothiazole, 45 parts of sodium tripolyphosphate, and 10 parts of zinc chloride; and the solvent is a mixed solution of ethanol and deionized water with a volume ratio of 1:5.

[0078] The preparation method comprises the following steps: (1) dissolving mercaptobenzothiazole in ethanol with a solvent ratio of 1 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (2) dissolving sodium tripolyphosphate in deionized water with a solvent ratio of 5 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (3) slowly adding the solution obtained in (2) into the mixed solution obtained in (1), and adding zinc chloride, and stirring until fully mixed. The stirring temperature is 25 DEG C, and the stirring time is 30 min.

[0079] The inhibitor is added dropwise to the coating defect position, and test results show that the inhibitor has an inhibition rate of 89% on the filamentous corrosion of the zinc-aluminum-magnesium plate.

[0080] Comparative Example 1

[0081] An inhibitor for a zinc-aluminum-magnesium plated steel plate, the inhibitor comprising a solute and a solvent, wherein the solute accounts for 2 wt% of the inhibitor, and the solvent accounts for 98 wt% of the inhibitor; wherein the solute is mercaptobenzothiazole, and the solvent is a mixed solution of ethanol and deionized water with a volume ratio of 1:5.

[0082] The preparation method comprises the following steps: (1) dissolving mercaptobenzothiazole in ethanol with a solvent ratio of 1 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (2) dissolving sodium tripolyphosphate in deionized water with a solvent ratio of 5 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (3) slowly adding the solution obtained in (2) into the mixed solution obtained in (1), and adding zinc chloride, and stirring until fully mixed. The stirring temperature is 25 DEG C, and the stirring time is 30 min.

[0083] The inhibitor is added dropwise to the coating defect position, and test results show that the inhibitor has an inhibition rate of 89% on the filamentous corrosion of the zinc-aluminum-magnesium plate.

[0084] Comparative Example 2

[0085] The corrosion inhibitor for zinc-aluminum-magnesium plated steel plate comprises a solute and a solvent, wherein the solute accounts for 2wt% of the corrosion inhibitor, and the solvent accounts for 98wt% of the corrosion inhibitor; the solute is composed of sodium tripolyphosphate and zinc chloride, and the mass ratio of sodium tripolyphosphate to zinc chloride is 9:2; and the solvent is a mixed solution of ethanol and deionized water, and the volume ratio of ethanol to deionized water is 1:5.

[0086] The preparation method comprises the following steps: dissolving sodium tripolyphosphate and zinc chloride in the solvent and stirring until completely dissolved; the stirring temperature is 40°C, and the stirring time is 30 min.

[0087] The corrosion inhibitor is added dropwise to the coating defect position, and the corrosion inhibition rate of the corrosion inhibitor on the filamentous corrosion of the zinc-aluminum-magnesium plate is 35% through test.

[0088] Comparative Example 3

[0089] The corrosion inhibitor for zinc-aluminum-magnesium plated steel plate comprises a solute and a solvent, wherein the solute accounts for 2wt% of the corrosion inhibitor, and the solvent accounts for 98wt% of the corrosion inhibitor; the solute is composed of sodium tripolyphosphate and zinc chloride, and the mass ratio of sodium tripolyphosphate to zinc chloride is 9:2; and the solvent is a mixed solution of ethanol and deionized water, and the volume ratio of ethanol to deionized water is 1:5.

[0090] The preparation method comprises the following steps: (1) dissolving mercaptobenzothiazole in 1 / 6 of the solvent (ethanol) to prepare a solution with a certain concentration, and stirring until completely dissolved; (2) dissolving sodium tripolyphosphate in 5 / 6 of the solvent (deionized water) to prepare a solution with a certain concentration, and stirring until completely dissolved; (3) slowly adding the solution obtained in (2) into the mixed solution obtained in (1), and adding zinc chloride, and stirring until fully mixed; the stirring temperature is 40°C, and the stirring time is 30 min.

[0091] The corrosion inhibitor is added dropwise to the coating defect position, and the corrosion inhibition rate of the corrosion inhibitor on the filamentous corrosion of the zinc-aluminum-magnesium plate is 58% through test.

[0092] Comparative Example 4

[0093] The corrosion inhibitor for zinc-aluminum-magnesium plated steel plate comprises a solute and a solvent, wherein the solute accounts for 2wt% of the corrosion inhibitor, and the solvent accounts for 98wt% of the corrosion inhibitor; the solute is composed of sodium tripolyphosphate and zinc chloride, and the mass ratio of sodium tripolyphosphate to zinc chloride is 9:2; and the solvent is a mixed solution of ethanol and deionized water, and the volume ratio of ethanol to deionized water is 1:5.

[0094] The preparation method comprises the following steps: (1) dissolving mercaptobenzothiazole in ethanol with a solvent ratio of 1 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (2) dissolving sodium tripolyphosphate in deionized water with a solvent ratio of 5 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (3) slowly adding the solution obtained in (2) into the mixed solution obtained in (1), and adding zinc chloride, and stirring until fully mixed. The stirring temperature is 40 DEG C, and the stirring time is 30 min.

[0095] The inhibitor is added dropwise to the coating defect position, and test results show that the inhibition rate of the inhibitor on the filamentous corrosion of the zinc-aluminum-magnesium plate is 54%.

[0096] Comparative Example 5

[0097] An inhibitor for a zinc-aluminum-magnesium plated steel plate, the inhibitor comprising a solute and a solvent, wherein the solute accounts for 2 wt% of the inhibitor, and the solvent accounts for 98 wt% of the inhibitor; wherein the solute is composed of the following components, each component being in parts by weight: 56 parts of mercaptobenzothiazole, 36 parts of sodium tripolyphosphate, and 8 parts of zinc chloride; and the solvent is a mixed solution of ethanol and deionized water, with a volume ratio of 1:5.

[0098] The preparation method comprises the following steps: (1) dissolving mercaptobenzothiazole in ethanol with a solvent ratio of 1 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (2) dissolving sodium tripolyphosphate in deionized water with a solvent ratio of 5 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (3) slowly adding the solution obtained in (2) into the mixed solution obtained in (1), and adding zinc chloride, and stirring until fully mixed. The stirring temperature is 40 DEG C, and the stirring time is 30 min.

[0099] The inhibitor is added dropwise to the coating defect position, and test results show that the inhibition rate of the inhibitor on the filamentous corrosion of the zinc-aluminum-magnesium plate is 48%.

[0100] Comparative Example 6

[0101] An inhibitor for a zinc-aluminum-magnesium plated steel plate, the inhibitor comprising a solute and a solvent, wherein the solute accounts for 2 wt% of the inhibitor, and the solvent accounts for 98 wt% of the inhibitor; wherein the solute is composed of the following components, each component being in parts by weight: 34 parts of mercaptobenzothiazole, 54 parts of sodium tripolyphosphate, and 12 parts of zinc chloride; and the solvent is a mixed solution of ethanol and deionized water, with a volume ratio of 1:5.

[0102] The preparation method comprises the following steps: (1) dissolving mercaptobenzothiazole in ethanol with a solvent ratio of 1 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (2) dissolving sodium tripolyphosphate in deionized water with a solvent ratio of 5 / 6 to prepare a solution with a certain concentration, and stirring until completely dissolved; (3) slowly adding the solution obtained in (2) into the mixed solution obtained in (1), and adding zinc chloride, and stirring until fully mixed. The stirring temperature is 40 DEG C, and the stirring time is 30 min.

[0103] The corrosion inhibitor is added dropwise to the coating defect position, and through test, the corrosion inhibition rate of the corrosion inhibitor on the filamentous corrosion of the zinc-aluminum-magnesium plate is 56%.

[0104] In addition, one or more technical solutions in the embodiments of the present application have at least the following technical effects or advantages:

[0105] In the embodiments of the present application, the corrosion inhibition efficiency is high, the adsorption type corrosion inhibitor is compounded with the precipitation type corrosion inhibitor, the corrosion inhibition effect can be greatly improved, the corrosion occurrence time is prolonged, and the corrosion rate is delayed.

[0106] In the embodiments of the present application, the preparation method of the corrosion inhibitor is simple, the cost is low, the dosage is small, the toxicity is low, and there is no secondary pollution to the environment.

[0107] In the embodiments of the present application, the corrosion inhibitor system has no influence on the surface morphology and appearance of the steel plate, and does not affect the subsequent other properties. Therefore, the present application has a good application prospect in inhibiting the filamentous corrosion of zinc-aluminum-magnesium material.

[0108] The above is only the specific embodiment of the present application, so that those skilled in the art can understand or implement the present application. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A corrosion inhibitor for zinc-aluminum-magnesium coated steel sheets, characterized in that, The corrosion inhibitor comprises, by mass fraction: solute: 0.1%~10%, solvent: 90%~99.9%; wherein, by mass fraction, the chemical composition of the solute is: 30~50 parts of thiazole corrosion inhibitor, 30~50 parts of polyphosphate, and 5~30 parts of zinc salt.

2. The corrosion inhibitor according to claim 1, characterized in that, The solvent is a mixed solution of ethanol and deionized water, and the volume ratio of ethanol to deionized water is (1:5) to (1:20).

3. The corrosion inhibitor according to claim 1, characterized in that, The thiazole corrosion inhibitors include one or more of benzothiazole, mercaptophenylprophiazole, benzothiadiazole, mercaptophenylprophiazole sodium, and thiol-phenylprophiazole sodium.

4. The corrosion inhibitor according to claim 1, characterized in that, The polyphosphate includes one or more of sodium tripolyphosphate and sodium hexametaphosphate.

5. The corrosion inhibitor according to claim 1, characterized in that, The zinc salt includes one or more of zinc chloride, zinc nitrate, and zinc sulfate.

6. The corrosion inhibitor according to claim 1, characterized in that, The corrosion inhibitor comprises, by mass fraction, 1% to 5% solute and 95% to 99% solvent; wherein, by mass fraction, the chemical composition of the solute comprises 40 to 50 parts of thiazole corrosion inhibitor, 40 to 50 parts of polyphosphate, and 5 to 15 parts of zinc salt, and the solvent is a mixed solution of ethanol and deionized water, wherein the volume ratio of ethanol to deionized water is 1:

5.

7. A method for preparing the corrosion inhibitor according to any one of claims 1 to 6, characterized in that, The method includes: The thiazole corrosion inhibitor was dissolved in ethanol and stirred for the first time to obtain the first solution; The polyphosphate was dissolved in deionized water and stirred a second time to obtain a second solution; The second solution is added to the first solution, followed by the addition of zinc salt, and then a third stirring is performed to obtain the corrosion inhibitor.

8. The method according to claim 7, characterized in that, The temperature of the first stirring, the second stirring and the third stirring are all 20℃~50℃, and the time of the first stirring, the second stirring and the third stirring are all 30min~60min.

9. A composite protective film, characterized in that, The composite protective film is formed by the corrosion inhibitor described in any one of claims 1 to 6 through adsorption and precipitation reaction, and the composite protective film formed by the corrosion inhibitor has a corrosion inhibition rate of ≥70% against filamentous corrosion of zinc-aluminum-magnesium steel plate.

10. The composite protective film according to claim 9, characterized in that, The composite protective film includes an adsorption-type protective film and a precipitation-type protective film, wherein the precipitation-type protective film partially fills the molecular gaps in the adsorption-type protective film.

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