Preparation and application methods of corrosion-resistant polyurea coatings with intercalated LDH / MoS2 corrosion inhibitors

Abstract

A method for preparing and applying a corrosion-resistant polyurea coating with intercalated LDH / MoS2 corrosion inhibitor synergistic enhancement is disclosed. The preparation method includes the following steps: preparing intercalated LDH corrosion inhibitor using a hydrothermal method; preparing an intercalated LDH / MoS2 heterostructure using a combination of hydrothermal method and in-situ growth; preparing a polyurea matrix; and mixing the intercalated LDH / MoS2 heterostructure into the polyurea matrix and performing dispersion and defoaming treatment. This preparation method constructs an intercalated LDH / MoS2 heterostructure composite filler in situ within the polyurea matrix, achieving efficient synergy between active protection mechanisms and passive physical barriers, and ensuring high compatibility between the filler system and the polyurea matrix. Ultimately, a polyurea composite coating with excellent long-lasting corrosion resistance and superior comprehensive performance is obtained to meet the long-term protection requirements under extremely harsh environments.

Description

Technical Field

[0001] This invention relates to the field of corrosion-resistant coating technology, and more specifically, to a method for preparing and applying a corrosion-resistant polyurea coating with corrosion inhibitor intercalation LDH / MoS2 synergistic reinforcement. Background Technology

[0002] Anti-corrosion coatings are widely used for corrosion protection of engineering structures and equipment in marine environments such as ships, lighthouses, offshore wind power, and submarine pipelines. However, the existing anti-corrosion materials still have insufficient anti-corrosion effects and cannot meet the long-term protection requirements in extremely harsh environments. Summary of the Invention

[0003] Some embodiments of the present invention provide a method for preparing a corrosion inhibitor-intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coating, the preparation method comprising the following steps:

[0004] Corrosion inhibitor intercalated LDH was prepared using a hydrothermal method;

[0005] Corrosion inhibitor-intercalated LDH / MoS2 heterostructures were prepared using a hydrothermal method combined with in-situ growth.

[0006] Preparation of polyurea matrix; and

[0007] The corrosion inhibitor intercalated LDH / MoS2 heterostructure is incorporated into the polyurea matrix and then dispersed and defoamed.

[0008] In some embodiments, the preparation of corrosion inhibitor intercalated LDH using a hydrothermal method includes the following steps:

[0009] Prepare a first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and a corrosion inhibitor;

[0010] The first mixed solution is placed in a reaction vessel for hydrothermal reaction to obtain the first reactant;

[0011] The first reactant is washed, centrifuged to obtain a first precipitate, and then dried.

[0012] In some embodiments, the preparation of the first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and corrosion inhibitor includes the following steps:

[0013] Magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and corrosion inhibitor were mixed and dissolved in deionized water and stirred evenly to obtain an initial mixed solution.

[0014] Prepare an alkaline sodium hydroxide solution by dissolving sodium hydroxide in deionized water;

[0015] The alkaline sodium hydroxide solution is added dropwise to the initial mixed solution until the pH of the initial mixed solution reaches 11.

[0016] In some embodiments, the molar ratio of magnesium nitrate hexahydrate to aluminum nitrate nonahydrate and the corrosion inhibitor is 3:1:3.

[0017] In some embodiments, the preparation of the corrosion inhibitor intercalated LDH / MoS2 heterostructure using a hydrothermal method combined with in-situ growth includes the following steps:

[0018] Prepare a second mixed solution of ammonium molybdate tetrahydrate, thiourea, and corrosion inhibitor LDH;

[0019] The second mixed solution was placed in a reaction vessel for hydrothermal in-situ growth to obtain the second reactant.

[0020] The second reactant is washed, centrifuged to obtain a second precipitate, and then dried.

[0021] In some embodiments, the mass ratio of ammonium molybdate tetrahydrate, thiourea, and corrosion inhibitor intercalated LDH is 1:3:1.

[0022] In some embodiments, the preparation of the polyurea matrix includes the following steps:

[0023] Preparation of semi-prepolymers;

[0024] Preparation of chain extenders; and

[0025] The semi-prepolymer and chain extender are mixed and stirred in a predetermined ratio.

[0026] In some embodiments, incorporating the corrosion inhibitor intercalated LDH / MoS2 heterostructure into the polyurea matrix and performing dispersion and defoaming treatment includes the following steps:

[0027] The corrosion inhibitor intercalated LDH / MoS2 heterostructure is incorporated into the polyurea matrix;

[0028] The polyurea matrix with intercalated LDH / MoS2 heterostructure containing corrosion inhibitors was subjected to dispersion and defoaming treatment by ultrasonic vibration.

[0029] In some embodiments, the mass ratio of the corrosion inhibitor intercalated LDH / MoS2 heterostructure to the polyurea matrix is ​​1:50.

[0030] Some embodiments of the present invention provide an application method for a corrosion inhibitor-intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coating. The corrosion inhibitor-intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coating is prepared using the preparation method described in the foregoing embodiments. The application method includes the following steps:

[0031] The corrosion inhibitor-intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coating is applied to the surface to be protected against corrosion; and

[0032] Perform the drying and curing process at a predetermined temperature.

[0033] Compared with related technologies, the above-described solutions of the present invention have at least the following beneficial effects:

[0034] The preparation method provided by this invention constructs a corrosion inhibitor intercalated LDH / MoS2 heterostructure composite filler in situ within a polyurea matrix, achieving efficient synergy between active protection mechanisms and passive physical barriers, and ensuring high compatibility between the filler system and the polyurea matrix. Ultimately, a polyurea composite coating with excellent long-lasting corrosion resistance and superior comprehensive performance is obtained to meet the long-lasting protection requirements under extremely harsh environments. Attached Figure Description

[0035] Figure 1 A flowchart is shown showing a method for preparing corrosion-resistant polyurea coatings with intercalated corrosion inhibitors (LDH / MoS2) synergistic reinforcement according to some embodiments of the present invention;

[0036] Figure 2 for Figure 1 Detailed flowchart of step S100;

[0037] Figure 3 for Figure 2 The detailed flowchart of step S110;

[0038] Figure 4 for Figure 1 The detailed flowchart of step S200;

[0039] Figure 5 for Figure 1 The detailed flowchart of step S300;

[0040] Figure 6 for Figure 1 The detailed flowchart of step S400;

[0041] Figure 7 A flowchart is shown illustrating the application method of corrosion inhibitor intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coatings provided in some embodiments of the present invention. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0043] In related technologies, polyurea coatings (PUA) are generated in situ through a high-speed reaction between diisocyanate and polyamines. Their unique microphase separation structure (flexible soft segments providing elasticity, and rigid hard segments forming physical cross-links through a network of urea bonds and strong hydrogen bonds) endows them with excellent mechanical strength, outstanding chemical corrosion resistance, abrasion resistance, and weather resistance. Their designable molecular structure (by controlling the –NCO / –NH2 equivalent ratio) and solvent-free application characteristics make them highly valuable in heavy-duty anti-corrosion engineering (such as marine engineering steel structures, chemical storage tank linings, and underground pipeline protection).

[0044] Traditional polyurea coatings still face fundamental challenges in long-term, harsh corrosive environments: the free volume and inherent defects of molecular chains at the microscopic level allow corrosive media, especially small molecules of water, oxygen, and chloride ions, to slowly penetrate. Once these media reach the coating / metal interface, they trigger interfacial electrochemical corrosion, leading to coating failure and substrate damage.

[0045] In the technical path to improve the long-term corrosion resistance of metal protective coatings, introducing functional fillers into the polymer matrix is ​​a key strategy.

[0046] Corrosion inhibitors, such as 2-mercaptobenzimidazole (MBI), can actively suppress corrosion reactions of metal substrates through chemisorption or film formation mechanisms. Layered bimetallic hydroxides (LDHs), a collective term for hydrotalcite (HT) and hydrotalcite-like compounds (HTLCs), often serve as ideal carriers for corrosion inhibitors due to their unique interlayer anion exchange capacity, enabling controlled release. Their layered structure also provides a certain degree of physical barrier effect. Molybdenum disulfide (MoS2), as a typical two-dimensional nanosheet, effectively delays the corrosion of water, oxygen, and corrosive ions, such as Cl, due to its excellent chemical stability, high specific surface area, and significant "maze effect." - , the penetration and diffusion.

[0047] However, introducing these components alone or through simple physical blending has obvious limitations: direct addition of corrosion inhibitors can easily lead to initial burst release and insufficient protection in the later stages; when LDH is used as a carrier, its physical barrier efficiency is limited by inherent interlayer spacing and dispersion issues; although MoS2 has excellent passive barrier performance, it lacks active corrosion inhibition function; and due to weak interfacial bonding and poor synergistic effect between different components, it is difficult to fully leverage the combined advantages of "active intelligent release" and "efficient physical barrier".

[0048] To overcome these limitations, the present invention provides a method for preparing a corrosion-resistant polyurea coating with synergistic reinforcement of LDH / MoS2 and corrosion inhibitor intercalation. The preparation method includes the following steps: preparing LDH intercalation corrosion inhibitor by hydrothermal method; preparing LDH / MoS2 heterostructure by hydrothermal method combined with in-situ growth method; preparing polyurea matrix; and mixing the LDH / MoS2 heterostructure into the polyurea matrix and performing dispersion and defoaming treatment.

[0049] The preparation method provided by this invention constructs a corrosion inhibitor intercalated LDH / MoS2 heterostructure composite filler in situ within a polyurea matrix, achieving efficient synergy between active protection mechanisms and passive physical barriers, and ensuring high compatibility between the filler system and the polyurea matrix. Ultimately, a polyurea composite coating with excellent long-lasting corrosion resistance and superior comprehensive performance is obtained to meet the long-lasting protection requirements under extremely harsh environments.

[0050] The optional embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0051] Figure 1 A flowchart illustrating a method for preparing a corrosion-resistant polyurea coating with intercalated LDH / MoS2 as a corrosion inhibitor, according to some embodiments of the present invention, is shown. Some embodiments of the present invention provide a method for preparing a corrosion-resistant polyurea coating with intercalated LDH / MoS2 as a corrosion inhibitor, such as... Figure 1 As shown, the preparation method includes the following steps:

[0052] S100: Corrosion inhibitor intercalated LDH was prepared using a hydrothermal method;

[0053] S200: Corrosion inhibitor intercalated LDH / MoS2 heterostructures were prepared by a combination of hydrothermal method and in-situ growth.

[0054] S300: Preparation of polyurea matrix;

[0055] S400: The corrosion inhibitor intercalated LDH / MoS2 heterostructure is mixed into the polyurea matrix and then dispersed and defoamed.

[0056] The corrosion-resistant polyurea coating with intercalated LDH / MoS2 corrosion inhibitor, prepared using the above method, achieves long-lasting, intelligent, and synergistic protection against corrosive media penetration, while also possessing excellent mechanical properties and applicability for application. Its working mechanism is as follows: A heterostructure of intercalated LDH / MoS2 corrosion inhibitor is constructed through in-situ growth, utilizing the corrosion inhibitor loaded between the intercalated LDH layers to respond to Cl... -Ion-triggered controlled release forms an active protective film at the metal interface; simultaneously, the dense physical barrier formed by the interlacing of MoS2 and LDH sheets significantly extends the medium penetration path; in addition, the filler surface groups (–OH / S) form strong interfacial bonds with polyurea bonds. The above-mentioned active corrosion inhibition, physical barrier and interfacial reinforcement work synergistically to construct a multi-layered dynamic protective network, thereby enabling the coating to simultaneously obtain excellent corrosion resistance, high mechanical strength and good performance.

[0057] Figure 2 for Figure 1 A detailed flowchart of step S100 is provided in some embodiments, such as... Figure 2 As shown, step S100: the preparation of corrosion inhibitor intercalated LDH using a hydrothermal method includes the following steps:

[0058] S110: Prepare a first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and corrosion inhibitor;

[0059] S120: The first mixed solution is placed into a reaction vessel to carry out a hydrothermal reaction to obtain the first reactant;

[0060] S130: The first reactant is washed and centrifuged to obtain the first precipitate, which is then dried.

[0061] Corrosion inhibitor response of LDH intercalation loading Cl - Ion-triggered controlled release forms an active protective film at the metal interface, with the corrosion inhibitor being at least one of 2-mercaptobenzimidazole (MBI) and 2-mercaptobenzothiazole (MBT).

[0062] Figure 3 for Figure 2 A detailed flowchart of step S110 is provided in some embodiments, such as... Figure 3 As shown, step S110: preparing the first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and corrosion inhibitor includes the following steps:

[0063] S111: Mix magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and corrosion inhibitor in deionized water and stir until homogeneous to obtain an initial mixed solution;

[0064] S112: Prepare an alkaline sodium hydroxide solution by dissolving sodium hydroxide in deionized water;

[0065] S113: Add the sodium hydroxide alkaline solution dropwise into the initial mixed solution until the pH value of the initial mixed solution is 11.

[0066] In some embodiments, in step S111, the molar ratio of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and the corrosion inhibitor is 3:1:3. Magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and the corrosion inhibitor are dissolved in deionized water according to the above molar ratio and stirred until homogeneous to obtain an initial mixed solution.

[0067] In step S112, NaOH powder is dissolved in deionized water and stirred until homogeneous to obtain an alkaline sodium hydroxide solution.

[0068] In step S113, the alkaline sodium hydroxide solution is added dropwise to the initial mixed solution while stirring. The pH value of the initial mixed solution is monitored by a pH meter until the pH value is 11, at which point the addition is stopped. This yields a first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and a corrosion inhibitor.

[0069] In step S120, the first mixed solution is transferred to a reaction vessel for hydrothermal reaction, maintaining a first predetermined temperature, for example, 120°C, and heated for 10~14 hours. After heating is completed, the mixture is cooled to obtain a precipitate, namely the first reactant.

[0070] In step S130, the first reactant is cleaned with deionized water and then cleaned again with anhydrous ethanol. These two cleaning processes can be performed multiple times. Subsequently, the first reactant is centrifuged at a speed of 2000~4000 RPM for 8~12 min. The centrifuged first reactant is then placed in a petri dish and dried at 70℃~80℃ for 10~14 h to obtain the corrosion inhibitor intercalated LDH, denoted as LDH-MBI.

[0071] Figure 4 for Figure 1 A detailed flowchart of step S200 is provided in some embodiments, such as... Figure 4 As shown, step S200: The preparation of the corrosion inhibitor intercalated LDH / MoS2 heterostructure using a hydrothermal method combined with in-situ growth includes the following steps:

[0072] S210: Prepare a second mixed solution of ammonium molybdate tetrahydrate, thiourea and corrosion inhibitor LDH;

[0073] S220: The second mixed solution is placed into a reactor for hydrothermal in-situ growth to obtain the second reactant;

[0074] S230: The second reactant is washed, centrifuged to obtain a second precipitate, and then dried.

[0075] In some embodiments, the mass ratio of ammonium molybdate tetrahydrate, thiourea, and corrosion inhibitor intercalated LDH is 1:3:1.

[0076] Specifically, in step S210, ammonium molybdate tetrahydrate, thiourea, and LDH-MBI are weighed and mixed according to the mass ratio, added to deionized water and stirred evenly to obtain a second mixed solution.

[0077] In step S220, the second mixed solution is transferred to a reactor for hydrothermal in-situ growth, maintaining a second predetermined temperature, for example, 180°C for 10-14 hours. After heating, the mixture is cooled to obtain a precipitate, i.e., the second reactant.

[0078] In a high-temperature, high-pressure (180℃) hydrothermal environment, the precursor thiourea (CH4N2S) decomposes to produce H2S gas. H2S then reacts with molybdate ions (MoO4²⁻) also adsorbed on the LDH surface. - A sulfurization reduction reaction occurs, ultimately generating MoS2 nanosheets. The key to this process is that the reactive sites are located directly on the layers and surface of the LDH, which precisely restricts the nucleation and growth of MoS2 on the LDH support, ultimately forming a heterostructure in which MoS2 nanosheets are tightly anchored and coated on the LDH surface.

[0079] In step S230, the second reactant is washed with deionized water and then washed again with anhydrous ethanol. The two washing processes can be performed multiple times. Subsequently, the second reactant is centrifuged at a speed of 2000 RPM to 4000 RPM for 8 to 12 minutes. The centrifuged second reactant is then placed in a petri dish and dried at 70°C to 80°C for 10 to 14 hours to obtain the corrosion inhibitor intercalated LDH / MoS2 heterostructure, denoted as MoS2@LDH-MBI.

[0080] Figure 5 for Figure 1 A detailed flowchart of step S300 is provided in some embodiments, such as... Figure 5 As shown, step S300: Preparing the polyurea matrix includes the following steps:

[0081] S310: Preparation of semi-prepolymer;

[0082] S320: Preparation of chain extenders;

[0083] S330: Mix the semi-prepolymer and chain extender in a predetermined ratio.

[0084] In these embodiments, the semi-prepolymer (component A) and the chain extender (component B) are mixed and thoroughly stirred with a machine agitator to form a polyurea matrix.

[0085] In step S310, the semi-prepolymer (component A) is synthesized by reacting polyetheramine D2000 with IPDI (isophorone diisocyanate). Specifically, polyetheramine D2000 and IPDI are mixed in a molar ratio of 1:3 and placed in an ice-water bath, stirred for 8-12 minutes. After stirring, the mixture is transferred to an oil bath and stirred at 70-80°C for 1-1.5 hours to obtain the polyurea prepolymer (component A).

[0086] In step S320, the chain extender (component B) is selected as E-100 chain extender. Specifically, E-100 chain extender is dissolved in DMF (N,N-dimethylformamide) and stirred until homogeneous.

[0087] In step S330, the polyurea matrix is ​​prepared by mixing and stirring a semi-prepolymer (component A) with a chain extender (component B). Specifically, the chain extender (component B) solution prepared in step S320 is added dropwise to the semi-prepolymer (component A) and stirred for 10-20 minutes to obtain the polyurea matrix.

[0088] Figure 6 for Figure 1 A detailed flowchart of step S400 is provided in some embodiments, such as... Figure 6 As shown, step S400: incorporating the corrosion inhibitor intercalated LDH / MoS2 heterostructure into the polyurea matrix and performing dispersion and defoaming treatment includes the following steps:

[0089] S410: The corrosion inhibitor intercalated LDH / MoS2 heterostructure is incorporated into the polyurea matrix;

[0090] S420: Dispersion and defoaming treatment is performed on polyurea matrices with intercalated LDH / MoS2 heterostructures containing corrosion inhibitors using ultrasonic vibration.

[0091] In some embodiments, the mass ratio of the corrosion inhibitor intercalated LDH / MoS2 heterostructure to the polyurea matrix is ​​1:50.

[0092] In step S410, MoS2@LDH-MBI is mixed into the polyurea matrix at a mass ratio of 1:50.

[0093] In step S420, MoS2@LDH-MBI is uniformly dispersed in the polyurea matrix by ultrasonic vibration and defoaming is performed. Specifically, ultrasonic vibration is performed for 10~20 minutes to obtain a corrosion inhibitor intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating, denoted as PUA-MoS2@LDH-MBI.

[0094] The surface groups (–OH / S) of fillers containing corrosion inhibitor intercalated LDH / MoS2 heterostructures can form strong interfacial bonds with polyurea bonds. Specifically, the surface groups of the filler (–OH of LDH and S atoms of MoS2) form strong hydrogen bonds / coordination bonds with polyurea bonds, simultaneously filling the free volume of the polymer, thus giving the coating excellent corrosion resistance while maintaining excellent mechanical properties.

[0095] The corrosion inhibitor-intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coating prepared by the preparation method of the above embodiments has the following beneficial effects:

[0096] MoS2 was grown in situ on the surface of LDH intercalated with corrosion inhibitors by hydrothermal method combined with in-situ growth method, and a compact heterostructure (MoS2@LDH-MBI / MBT) was constructed to realize the integrated integration of corrosion inhibitor carrier and physical barrier unit. It can be uniformly dispersed in polyurea matrix without additional dispersant, which significantly improves the compatibility of filler-matrix interface.

[0097] Synergistic reinforcement of active corrosion inhibition and passive barrier, corrosion inhibitor response of LDH interlayer loading Cl - Ion-triggered controllable release forms an active protective film at the metal interface. At the same time, the dense "maze" structure formed by the interlacing of MoS2 and LDH sheets physically blocks the penetration of media. The dual mechanisms work together to achieve long-lasting intelligent protection.

[0098] With low filler addition (e.g., 2.0 wt%) and process compatibility, the high-efficiency protective properties of the MoS2@LDH-MBI / MBT heterostructure can significantly improve corrosion resistance even at low loads, avoiding the problems of excessive filler leading to a sharp increase in polyurea viscosity, deterioration of construction rheology, and degradation of mechanical properties.

[0099] Interfacial bonding and matrix densification work together to ensure mechanical properties. The surface groups of the filler (–OH of LDH, S atoms of MoS2) form strong hydrogen bonds / coordination bonds with the polyurea bond, simultaneously filling the free volume of the polymer. This gives the coating excellent corrosion resistance while maintaining outstanding mechanical properties.

[0100] Figure 7 This document illustrates a flowchart of an application method for a corrosion inhibitor-intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coating provided in some embodiments of the present invention. Some embodiments of the present invention provide an application method for a corrosion inhibitor-intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coating, such as... Figure 7 As shown, the corrosion inhibitor-intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coating is prepared using the preparation method described in the foregoing embodiments, and the application method includes the following steps:

[0101] S710: Apply the corrosion inhibitor-intercalated LDH / MoS2 synergistically enhanced corrosion-resistant polyurea coating to the surface to be protected against corrosion;

[0102] S720: Perform drying and curing operations at a predetermined temperature.

[0103] In step S710, the corrosion inhibitor-intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coating is uniformly applied to the surface to be protected against corrosion, such as a metal surface, with a coating thickness of, for example, 80~150 μm. The surface to be protected against corrosion can be pre-treated, specifically by cleaning with acetone and drying, and by sanding the surface to make it smooth.

[0104] In step 720, the surface to be protected from corrosion coated with paint is dried in an environment of 70°C to 80°C for 10 to 14 hours.

[0105] The following describes specific embodiments and comparative examples of the manufacturing method of the present invention. For ease of comparison, in the following specific embodiments and comparative examples, the prepared coating was applied to the surface of a Q235 steel sheet sample and dried and cured to obtain a coating. The anti-corrosion performance of each coating was then compared.

[0106] Example 1

[0107] Example 1 provides a method for preparing a corrosion-resistant polyurea coating with intercalated LDH / MoS2 as a corrosion inhibitor, specifically including the following steps:

[0108] S1: Preparation of corrosion inhibitor intercalated LDH using a hydrothermal method

[0109] Specifically, 2.56g of magnesium nitrate hexahydrate, 1.25g of aluminum nitrate nonahydrate, and 1.5g of MBI were weighed and mixed in a beaker, and 90ml of deionized water was added and stirred until homogeneous to obtain an initial mixed solution. 2g of NaOH powder was weighed and placed in a beaker, and 25ml of deionized water was added and stirred until homogeneous to obtain an alkaline sodium hydroxide solution. The alkaline sodium hydroxide solution was added dropwise to the initial mixed solution while stirring, and the pH value of the initial mixed solution was monitored using a pH meter until the pH value reached 11. The addition was then stopped, thus obtaining a first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and a corrosion inhibitor.

[0110] The first mixed solution was transferred to a reaction vessel for hydrothermal reaction, and heated at 120°C for 12 hours. After heating was completed, the mixture was cooled to obtain a precipitate, which is the first reactant.

[0111] The first reactant was washed three times with deionized water and then three times with anhydrous ethanol. The reactant was then centrifuged at 3000 RPM for 10 min. The centrifuged reactant was then placed in a petri dish and dried in an oven at 75°C for 12 h to obtain the corrosion inhibitor intercalated LDH, denoted as LDH-MBI.

[0112] S2: A corrosion inhibitor intercalated LDH / MoS2 heterostructure was prepared by a combination of hydrothermal method and in-situ growth.

[0113] Specifically, 2g of ammonium molybdate tetrahydrate, 6g of thiourea, and 2g of LDH-MBI were weighed into a beaker, and 100ml of deionized water was added and stirred evenly to obtain a second mixed solution. The second mixed solution was transferred to a reaction vessel for hydrothermal in-situ growth, and heated at 180℃ for 12h. After heating, the mixture was cooled to obtain a precipitate, which is the second reactant. The second reactant was washed three times with deionized water and then three times with anhydrous ethanol. Subsequently, the second reactant was centrifuged at 3000RPM for 10min. The centrifuged second reactant was then placed in a petri dish and dried in an oven at 75℃ for 12h to obtain a corrosion inhibitor intercalated LDH / MoS2 heterostructure, denoted as MoS2@LDH-MBI.

[0114] S3: Preparation of polyurea matrix.

[0115] Specifically, 10g of polyetheramine D2000 and 3.42g of IPDI were weighed and placed in an ice-water bath, stirred for 10 minutes, and after stirring, transferred to an oil bath and stirred at 75°C for 1 hour to obtain polyurea prepolymer (component A); 1.63g of E-100 chain extender (component B) was dissolved in 10ml of DMF (N,N-dimethylformamide) and stirred evenly; the chain extender (component B) solution was added dropwise to the semi-prepolymer (component A) and stirred for 15 minutes to obtain polyurea matrix.

[0116] S4: The corrosion inhibitor intercalated LDH / MoS2 heterostructure is mixed into the polyurea matrix and then dispersed and defoamed.

[0117] Specifically, 0.3g of MoS2@LDH-MBI was mixed into the polyurea matrix, and the MoS2@LDH-MBI was evenly dispersed in the polyurea matrix by ultrasonic vibration and defoaming was performed. Specifically, ultrasonic vibration was performed for 15 minutes to obtain a corrosion-resistant polyurea coating with LDH / MoS2 synergistic reinforcement by corrosion inhibitor intercalation, denoted as PUA-MoS2@LDH-MBI.

[0118] This embodiment uses a corrosion inhibitor-intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coating to create a coating for subsequent corrosion resistance testing. Specifically, it includes the following steps:

[0119] PUA-MoS2@LDH-MBI was uniformly coated onto the surface of a pretreated Q235 steel sheet, with a film thickness of approximately 100 μm. The sample was then dried in an oven at 75°C for 12 hours to complete curing, resulting in a corrosion-resistant polyurea coating with LDH / MoS2 synergistic reinforcement, denoted as PUA-MoS2@LDH-MBI layer. In some embodiments, the aforementioned pretreatment included acetone cleaning and drying, and surface sanding to make it smooth.

[0120] Example 2

[0121] Example 2 provides a method for preparing a corrosion-resistant polyurea coating with LDH / MoS2 synergistic reinforcement by corrosion inhibitor intercalation. The preparation method in Example 2 is basically the same as that in Example 1, except that MBT is used instead of MBI as the corrosion inhibitor in the preparation method of Example 2. The resulting coating is denoted as PUA-MoS2@LDH-MBT. The coating prepared by the same method as the coating in Example 1 is denoted as PUA-MoS2@LDH-MBT layer.

[0122] Comparative Example 1

[0123] Comparative Example 1 provides a method for preparing a corrosion-resistant polyurea coating. The preparation method in Comparative Example 1 is basically the same as that in Example 1, except that the preparation method in Comparative Example 1 does not use a corrosion inhibitor. All other parameters are the same as in Example 1. The resulting coating is denoted as PUA-MoS2@LDH. The coating prepared by means of a method that is basically the same as that in Example 1 is denoted as PUA-MoS2@LDH layer.

[0124] Comparative Example 2

[0125] Comparative Example 2 provides a method for preparing a corrosion-resistant polyurea coating. The preparation method in Comparative Example 2 is basically the same as that in Example 1, except that MoS2 is not used in the preparation method of Comparative Example 2. Specifically, after obtaining LDH-MBI in step S1, step S3 is directly performed. In step S4, MoS2@LDH-MBI is replaced with an equivalent mass of LDH-MBI. The remaining steps are the same. The resulting coating is denoted as PUA-LDH-MBI. The coating prepared in a manner that is basically the same as the coating preparation method in Example 1 is denoted as the PUA-LDH-MBI layer.

[0126] Comparative Example 3

[0127] Comparative Example 3 provides a method for preparing a corrosion-resistant polyurea coating. The preparation method in Comparative Example 3 is basically the same as that in Example 1, except that LDH is not used in the preparation method of Comparative Example 3. Specifically, steps S1 and S2 are omitted; step S3 is the same as in Example 1; in step S4, 0.3g of MoS2 is added to the polyurea matrix; the remaining steps are the same. The resulting coating is denoted as PUA-MoS2. The coating prepared in a manner that is basically the same as the coating preparation method in Example 1 is denoted as the PUA-MoS2 layer.

[0128] Comparative Example 4

[0129] Comparative Example 4 provides a method for preparing a corrosion-resistant polyurea coating. The preparation method in Comparative Example 4 is basically the same as that in Example 1, except that no filler is used in the preparation method in Comparative Example 4. Specifically, steps S1, S2, and S4 are omitted, and the polyurea matrix obtained in step S3 is directly used as a coating material, denoted as PUA. The coating prepared in a manner that is basically the same as the coating preparation method in Example 1 is denoted as the PUA layer.

[0130] To systematically evaluate the corrosion resistance of the LDH / MoS2 intercalated polyurea coating synergistically enhanced by the corrosion inhibitor of the present invention, electrochemical impedance spectroscopy (EIS) tests were conducted on the coating samples prepared in Examples 1, 2, 1, 2, 3, and 4 for 50 days. During the test, all samples were immersed in a simulated seawater environment, and their impedance data were collected periodically to monitor the changes in the corrosion resistance of the coating over time. By analyzing the changes in impedance modulus in the low-frequency region, the impermeability and long-term protective effect of different formulations of the coating were evaluated, aiming to verify the synergistic protection mechanism and superiority of the composite coating prepared by the present invention.

[0131] Table 1 shows the low-frequency impedance modulus (|Z|) of Bode plots for different samples during 50 days of immersion. 0.01 Hz (unit: Ω·cm²)

[0132] Table 1. Bode plot low-frequency impedance modulus values ​​of different samples during 50 days of immersion.

[0133]

[0134] The core of the corrosion resistance of organic polyurea coating systems lies in their resistance to the penetration of corrosive media, which can be quantitatively evaluated by the impedance modulus (Ω·cm²) in the low-frequency region using electrochemical impedance spectroscopy (EIS). Immersing each coating formulation in artificial seawater for 50 days and monitoring the impedance changes in real time (data shown in the table) shows that the low-frequency impedance modulus of the pure polyurea coating (PUA layer in Comparative Example 4) increased from the initial 1.8 × 10⁻⁶ Ω·cm². 9 The Ω·cm² decreased sharply to 9.0×10 7The Ω·cm² indicates that the corrosive medium rapidly penetrated the coating and induced electrochemical reactions at the metal / coating interface. Composite coatings with only a single functional filler also showed significant degradation, with the PUA-MoS2 layer (Comparative Example 3) decreasing from 2.4 × 10⁻⁶ Ω·cm². 9 Ω·cm² decreased to 1.6×10 8 Ω·cm², PUA-LDH-MBI layer (Comparative Example 2) from 2.6×10 9 Ω·cm² decreased to 1.4×10 8 The Ω·cm² value indicates that a single physical barrier or corrosion-inhibiting structure is insufficient to effectively block penetration in the long term; while the MoS2@LDH composite filler system without corrosion inhibitors (Comparative Example 1, PUA-MoS2@LDH layer) showed a value of 2.2 × 10⁻⁶ Ω·cm², indicating that a single physical barrier or corrosion-inhibiting structure is insufficient to effectively block penetration in the long term; while the MoS2@LDH composite filler system without 9 The Ω·cm² dropped rapidly to 4.0 × 10⁻⁶. 7 The resistance modulus of the coating, measured in Ω·cm², further demonstrates that the lack of active corrosion inhibition leads to early failure of the protective system. In contrast, the two synergistic heterostructure coatings constructed in this invention exhibit significantly superior performance: the impedance modulus of Example 1 (PUA-MoS2@LDH-MBI) increases from 5.2 × 10⁻⁶ Ω·cm². 9 Ω·cm² slowly decreased to 4.0×10 9 Ω·cm², Example 2 (PUA-MoS2@LDH-MBT) from 4.8 × 10 9 Ω·cm² decreased to 3.5×10 9 Ω·cm², both remained at 10 throughout the 50-day soaking period. 9 The corrosion resistance was on the order of Ω·cm², and the attenuation was the most gradual. This result fully verifies that the multiple synergistic mechanism of "controlled release of LDH-loaded corrosion inhibitor – MoS2 lamellar labyrinth effect – densification of filler-matrix interface" can effectively prolong the penetration path of corrosive media and continuously inhibit interfacial reactions, thereby endowing the coating with significantly better long-term corrosion resistance than all comparative examples.

[0135] The excellent long-term corrosion resistance of this coating system stems from its multi-layered synergistic protection mechanism: the MBI corrosion inhibitor loaded in the LDH interlayer can respond to the Cl in the environment. - The controlled release of ions, triggered by adsorption and coordination, allows them to migrate to the metal interface and form a dense passivation film, actively inhibiting cathodic corrosion. Simultaneously, the inherent exchangeable layered framework of LDH constructs a multi-level ion-trapping barrier within the coating, effectively intercepting corrosive ions (such as Cl-). - More importantly, the MoS2 sheets grown in situ on the surface of the corrosion inhibitor-intercalated LDH via a secondary hydrothermal method form a dense heterostructure (MoS2@LDH). This structure is interwoven within the polyurea matrix and, through a synergistic "maze effect," significantly extends the corrosion resistance of Cl. -The diffusion and penetration pathways of corrosive media such as H2O and O2 are blocked. Furthermore, the abundant active groups on the surface of the heterostructure filler (-OH from LDH, -S from MoS2) form a strong hydrogen bond and coordination bond network with the urea bonds (-NH-CO-NH-) in the polyurea molecular chain. This not only strengthens the filler-matrix interface bonding but also simultaneously densifies the polymer matrix structure, effectively blocking the penetration of media along the interface. The aforementioned mechanisms of "active corrosion inhibition," "ion capture," "efficient physical barrier," and "interface strengthening" are not isolated but synergistic and dynamically responsive, jointly constructing an intelligent and efficient multi-layered dynamic protective network. This becomes the core guarantee for the coating to achieve excellent impermeability and ultra-long service life in harsh corrosive environments (such as marine environments).

[0136] In summary, the low-frequency impedance modulus of the coating increases with immersion time from 10... 9 The magnitude smoothly decreases to 10. 8 -10 9 The variation pattern of Ω·cm² (especially the high initial value and slow decay rate of Example 1) fully verifies the innovation of this invention—the triple synergistic mechanism of "active intelligent slow release", "efficient physical barrier" and "interface strengthening" achieved by constructing a corrosion inhibitor intercalated LDH / MoS2 heterostructure plays a decisive role in significantly improving the impermeability of polyurea coatings and extending their service life in harsh environments (such as marine environments).

[0137] Table 2 shows the EDS atomic percentages (at%) of different coating cross-sections after 50 days of electrochemical immersion. After the 50-day electrochemical immersion test, SEM-EDS point / area scanning was performed on the peeled cross-sections of the six coatings, and the elemental atomic percentages (at%) are shown in Table 2. To highlight the differences between corrosion products (Fe, Cl) and functional components (Mg, Al, Mo, S, N), Na (introduced from seawater) is also listed separately. The data were measured in three different regions and averaged, totaling approximately 100% (rounding may result in a slight ±0.1% deviation in some columns).

[0138] Table 2. EDS atomic percentage (at%) at different coating cross-sections after 50 days of electrochemical immersion

[0139]

[0140] The EDS atomic percentage results above show that the structurally intact biomimetic coatings (Examples 1 and 2) exhibit almost no detectable corrosion products (Fe) and electrolyte characteristic element (Cl) in the cross-sectional area (total ≤1%). Meanwhile, these coatings still retain the characteristic elements magnesium (Mg) and aluminum (Al) of layered bimetallic hydroxides (LDH), as well as the elements molybdenum (Mo) and sulfur (S) corresponding to molybdenum disulfide (MoS2). This phenomenon strongly suggests that the MoS2 sheets and LDH layered framework remain stably embedded in the polyurea matrix network after immersion for up to 50 days; the exchangeable sites between LDH layers effectively capture the infiltrated chloride ions (Cl). - Simultaneously, it releases corrosion inhibitors MBI / MBT, enabling the coating / metal interface to remain in a passivated state for a long time, thereby almost completely inhibiting the dissolution and corrosion of the metal substrate.

[0141] In the comparative example 1 coating, which lacked a primary corrosion inhibitor, the contents of Fe and Cl increased significantly to a total of 7.9%, and the Na content was as high as 12.4%. This indicates that seawater electrolytes had penetrated extensively into the interfacial region, triggering a severe corrosion reaction. This result is consistent with the impedance modulus in its electrochemical impedance spectroscopy (EIS) data, which increased from 10... 9 The magnitude dropped sharply to 10 7 The phenomenon of Ω·cm² is completely consistent, mutually corroborating the failure of its protection.

[0142] In Comparative Example 2, where the MoS2 physical barrier was removed, or in Comparative Example 3, where the LDH support was removed, the Mo / S or Mg / Al signals disappeared in the cross-section, while the contents of Fe and Cl both increased to approximately 5%. This fully demonstrates that the absence of either the active corrosion inhibitor (LDH) or the efficient physical barrier (MoS2) significantly shortens the diffusion path of the corrosive medium in the coating and severely reduces the retention efficiency of the corrosion inhibitor at the interface.

[0143] The pure polyurea coating without any added functional fillers (Comparative Example 4), although its nitrogen (N) and oxygen (O) content indicates that the polyurea skeleton structure is still present, has a combined Fe (3.8%) and Cl (2.6%) content of 6.4%. This proves that relying solely on the physical barrier effect of the hydrophobic segments of polyurea itself is insufficient to effectively block the penetration and accumulation of corrosive media during long-term immersion.

[0144] In summary, the low chlorine / iron content and high magnesium / aluminum / molybdenum / sulfur elemental distribution characteristics shown by EDS analysis are consistent with the impedance values ​​that can be maintained at 10 for a long period of time in EIS testing. 9The excellent performance across these orders of magnitude is highly consistent. This further confirms, at the microscopic level of elemental composition and distribution, the key role of the triple synergistic mechanism of "MBI cathode passivation," "LDH ion capture," and "MoS2 lamellar labyrinth effect" in effectively suppressing electrolyte migration and metal substrate dissolution.

[0145] Finally, it should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.

[0146] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a corrosion-resistant polyurea coating with intercalated LDH / MoS2 corrosion inhibitor synergistic reinforcement, characterized in that, The preparation method includes the following steps: Corrosion inhibitor intercalated LDH was prepared using a hydrothermal method; Corrosion inhibitor-intercalated LDH / MoS2 heterostructures were prepared using a hydrothermal method combined with in-situ growth. Preparation of polyurea matrix; and The corrosion inhibitor intercalated LDH / MoS2 heterostructure is incorporated into the polyurea matrix and then dispersed and defoamed. The preparation of the corrosion inhibitor intercalated LDH / MoS2 heterostructure using a hydrothermal method combined with in-situ growth includes the following steps: Prepare a second mixed solution of ammonium molybdate tetrahydrate, thiourea, and corrosion inhibitor LDH; The second mixed solution was placed in a reactor for hydrothermal in-situ growth to obtain the second reactant.

2. The preparation method according to claim 1, characterized in that, The preparation of corrosion inhibitor intercalated LDH using the hydrothermal method includes the following steps: Prepare a first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and a corrosion inhibitor; The first mixed solution is placed in a reaction vessel for hydrothermal reaction to obtain the first reactant; The first reactant is washed, centrifuged to obtain a first precipitate, and then dried.

3. The preparation method according to claim 2, characterized in that, The preparation of the first mixed solution of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and corrosion inhibitor includes the following steps: Magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and corrosion inhibitor were mixed and dissolved in deionized water and stirred evenly to obtain an initial mixed solution. Prepare an alkaline sodium hydroxide solution by dissolving sodium hydroxide in deionized water; The alkaline sodium hydroxide solution is added dropwise to the initial mixed solution until the pH of the initial mixed solution reaches 11.

4. The preparation method according to claim 2 or 3, characterized in that, The molar ratio of magnesium nitrate hexahydrate, aluminum nitrate nonahydrate, and corrosion inhibitor is 3:1:

3.

5. The preparation method according to any one of claims 1 to 3, characterized in that, The preparation of the corrosion inhibitor intercalated LDH / MoS2 heterostructure using a hydrothermal method combined with in-situ growth also includes the following steps: The second reactant is washed, centrifuged to obtain a second precipitate, and then dried.

6. The preparation method according to claim 5, characterized in that, The mass ratio of ammonium molybdate tetrahydrate, thiourea, and corrosion inhibitor intercalated LDH is 1:3:

1.

7. The preparation method according to any one of claims 1 to 3, characterized in that, The preparation of the polyurea matrix includes the following steps: Preparation of semi-prepolymers; Preparation of chain extenders; and The semi-prepolymer and chain extender are mixed and stirred in a predetermined ratio.

8. The preparation method according to any one of claims 1 to 3, characterized in that, The process of incorporating the corrosion inhibitor-intercalated LDH / MoS2 heterostructure into the polyurea matrix and then dispersing and defoaming it includes the following steps: The corrosion inhibitor intercalated LDH / MoS2 heterostructure is incorporated into the polyurea matrix; The polyurea matrix with intercalated LDH / MoS2 heterostructure containing corrosion inhibitors was subjected to dispersion and defoaming treatment by ultrasonic vibration.

9. The preparation method according to claim 4, characterized in that, The mass ratio of the corrosion inhibitor intercalated LDH / MoS2 heterostructure to the polyurea matrix is ​​1:

50.

10. A method for applying a corrosion inhibitor-intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coating, characterized in that, The corrosion inhibitor-intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coating is prepared using the preparation method described in any one of claims 1 to 9, and the application method includes the following steps: The corrosion inhibitor-intercalated LDH / MoS2 synergistically reinforced corrosion-resistant polyurea coating is applied to the surface to be protected against corrosion; and Perform the drying and curing process at a predetermined temperature.

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