Chromium-free corrosion-resistant sol-gel conversion coating

Abstract

The invention relates to a chromium-free corrosion-resistant sol-gel conversion coating. The invention discloses a corrosion inhibitor coating composition. The corrosion inhibitor coating composition comprises a corrosion inhibitor, such as 2, 5-dimercapto-1, 3, 4-thiadiazole (DMCT), at least one active silane, and a catalyst. The active silane may include a tetraethoxysilane (TEOS), a vinyltriethoxysilane (VTS), a 3-glycidoxypropyltrimethoxysilane (GPTMS), a methyltrimethoxysilane (MTMS), or a combination of the tetraethoxysilane (TEOS), the vinyltriethoxysilane (VTS), the 3-glycidoxypropyltrimethoxysilane (GPTMS) and the methyltrimethoxysilane (MTMS). The corrosion inhibitor coating composition does not contain chromium. The catalyst may be zirconium isopropoxide or acetic acid. The corrosion inhibitor may also include a thiadiazole, a benzotriazole, an imidazole, or a combination thereof. An article and a method of providing a corrosion inhibitor coating are also disclosed.

Description

Technical Field

[0001] This teaching generally relates to chromium-free corrosion-inhibiting coatings, and more specifically to chromium-free corrosion-inhibiting coatings comprising sol-gel. Background Technology

[0002] Chromium corrosion inhibitors (also known as chromium conversion coatings) have been widely used for decades due to their performance and durability in preventing corrosion of steel, aluminum, and other alloys used in aerospace manufacturing. Recently, global regulations have been restricting the use of chromium conversion coatings. New organic corrosion inhibitor molecules have been developed to replace chromium in certain applications. These organic corrosion inhibitor molecules need to react with multifunctional resins to form durable coatings containing these inhibitors. In some coatings, the inhibitors can be added directly to or applied to the panels of vehicles or aircraft. In this case, the corrosion inhibitor is dispersed within the coating but may not provide good adhesion to the substrate panel and any previously applied primer or epoxy coating on the substrate or panel.

[0003] Therefore, cross-linking may be required between coating molecules, and the inhibitors within the coating need time to react. For example, some epoxy systems are insufficiently reactive with these organic corrosion inhibitor systems, and the reactions required for cross-linking cannot be carried out within the limitations of the possible coating methods. In some cases, high temperatures and long reaction times are required to achieve sufficient reaction to provide adequate coating performance and adhesion.

[0004] Therefore, there is a need for corrosion-inhibiting compositions that offer easy reactivity within acceptable process limitations while providing acceptable or improved adhesion and corrosion inhibition. In particular, non-chromate primer systems require chromate conversion coatings to meet the requirements for adhesion promotion and corrosion resistance near metal surfaces. Summary of the Invention

[0005] A simplified overview is provided below to offer a basic understanding of certain aspects of one or more embodiments of this teaching. This overview is not an extensive summary, nor is it intended to identify key or essential elements of this teaching or to depict the scope of the invention. Rather, its primary purpose is merely to present one or more concepts in a simplified form as a prelude to the detailed description provided later.

[0006] This invention discloses a corrosion inhibitor coating composition. The corrosion inhibitor coating composition comprises a corrosion inhibitor such as 2,5-dimercapto-1,3,4-thiadiazole (DMCT). The composition also comprises at least one active silane and a catalyst. Embodiments of the corrosion inhibitor coating composition include cases where the at least one active silane may comprise tetraethoxysilane (TEOS). The at least one active silane may comprise vinyltriethoxysilane (VTS), 3-glycidoxypropyltrimethoxysilane (GPTMS), methyltrimethoxysilane (MTMS), or combinations thereof. The corrosion inhibitor coating composition does not contain chromium. The catalyst may comprise zirconium isopropoxide or acetic acid. The 2,5-dimercapto-1,3,4-thiadiazole (DMCT) is present in an amount of about 0.1% to about 5.0% of the total weight of the corrosion inhibitor coating composition. The at least one active silane may comprise a first active silane and a second active silane, and the weight ratio of the first active silane to the second active silane is about 0.5:1 to about 3:1. The corrosion inhibitor may also comprise thiadiazole, benzotriazole, imidazole, or combinations thereof.

[0007] This invention discloses an article. The article comprises a substrate and a corrosion inhibitor coating composition disposed on the surface of the substrate. The corrosion inhibitor coating composition may contain 2,5-dimercapto-1,3,4-thiadiazole (DMCT), at least one active silane, and a catalyst, wherein the at least one active silane may include tetraethoxysilane (TEOS), vinyltriethoxysilane (VTS), 3-glycidoxypropyltrimethoxysilane (GPTMS), or combinations thereof. Embodiments of the article may include cases where the corrosion inhibitor coating composition does not contain chromium. The catalyst may include zirconium isopropoxide or acetic acid. The 2,5-dimercapto-1,3,4-thiadiazole (DMCT) is present in an amount from about 0.1% to about 5.0% of the total weight of the corrosion inhibitor coating composition. The thickness of the corrosion inhibitor coating composition may be from about 100 nm to about 10 μm. The substrate may include metal, polymer, polymer composite material, or combinations thereof. The article may include cases where no adhesive or primer exists between the substrate and the corrosion inhibitor coating composition. The article is a component or part of an aerospace vehicle or a waterborne vehicle.

[0008] This invention discloses a method for providing a corrosion inhibitor coating, wherein the method includes forming a corrosion inhibitor coating composition having 2,5-dimercapto-1,3,4-thiadiazole (DMCT), at least one active silane, a catalyst, and a solvent; applying the corrosion inhibitor coating composition to a surface of a substrate; and exposing the corrosion inhibitor coating composition to a curing temperature. Embodiments of the method for preparing the corrosion inhibitor coating composition may include: the thickness of the applied corrosion inhibitor coating composition being from about 30 nm to about 10 μm, and the curing temperature being from about 15°C to about 150°C.

[0009] The features, functions, and advantages already discussed can be implemented independently in various embodiments or combined in other embodiments, and further details can be found in the following description. Attached Figure Description

[0010] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the teachings and, together with the specification, serve to explain the principles of this disclosure. In the figures:

[0011] Figure 1A A schematic diagram of a vehicle according to the present invention is shown.

[0012] Figure 1B The application of a structural component according to the present invention, comprising a corrosion-inhibiting composition coated onto an aerospace vehicle, is illustrated.

[0013] Figure 1C This is an additional cross-sectional schematic diagram of an exemplary corrosion-inhibiting coating composition in an environment according to the present invention.

[0014] Figures 2A to 2C The images are photographs of the exemplary coating according to Embodiment 1 of the present invention after application, after a 168-hour salt spray test, and after a 336-hour salt spray test.

[0015] Figures 3A to 3C The images are photographs of the exemplary coating according to Embodiment 2 of the present invention after application, after a 168-hour salt spray test, and after a 336-hour salt spray test.

[0016] Figures 4A to 4C The images are photographs of the exemplary coating according to Embodiment 3 of the present invention after application, after a 168-hour salt spray test, and after a 336-hour salt spray test.

[0017] Figures 5A to 5C The images are photographs of the exemplary coating according to Embodiment 4 of the present invention after application, after a 168-hour salt spray test, and after a 336-hour salt spray test.

[0018] It should be noted that some details in the diagrams have been simplified and drawn to facilitate understanding of this teaching, rather than to maintain strict structural accuracy, detail, and proportion. Detailed Implementation

[0019] Exemplary embodiments of this teaching will now be described in detail, examples of which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used throughout the drawings to refer to the same, similar, or related parts.

[0020] As used herein, “free from” or “substantially free from” a material may mean that, based on the total weight of the composition, component, or phase, the amount of said material in the composition, component, or phase is less than 10.0 wt%, less than 5.0 wt%, less than 3.0 wt%, less than 1.0 wt%, less than 0.1 wt%, less than 0.05 wt%, less than 0.01 wt%, less than 0.005 wt%, or less than 0.0001 wt%.

[0021] Furthermore, all numerical values ​​are indicated by “about” or “approximately” and experimental errors and fluctuations expected by those skilled in the art should be taken into account. It should be understood that all numerical values ​​and ranges disclosed herein are approximate values ​​and ranges. When referring to quantities or measurements, the terms “about,” “substantially,” or “approximately” indicate that the described feature, parameter, or value does not need to be precisely achieved. Instead, deviations or fluctuations (including, for example, tolerances, measurement errors, measurement accuracy limitations, and other factors known to those skilled in the art) may occur in quantities that do not impede the effect the feature is intended to provide. As used herein, “about” means within ±5% of the target value, maximum value, or minimum value.

[0022] All references cited in this article are incorporated herein by reference in their entirety. In the event of any discrepancy between the definitions in this invention and those in the cited references, the definitions in this invention shall prevail.

[0023] In an example of this invention, 2,5-dimercapto-1,3,4-thiadiazole (DMCT) is a corrosion inhibitor that can be used as an alternative to a chromium inhibitor in sol-gel conversion coating compositions used as corrosion-inhibiting coatings. This invention describes methods and formulations for sol-gel conversion coatings that improve corrosion resistance and promote adhesion by reducing the use of environmentally impactful coatings in aircraft or marine projects. The means of this invention can reduce the steps involved in the external coating process and minimize the potential toxic effects of chromium. The developed sol-gel conversion coatings have had their shelf life tested with DMCT and their corrosion resistance evaluated in salt spray tests according to ASTM B117, which will be described in more detail later.

[0024] The sol-gel corrosion-inhibiting composition can be applied as a thin film to a clean aluminum alloy (AA 2024) plate and cured at room temperature. The developed coating is transparent and passed a 336-hour salt spray test on AA2024 plates according to ASTM B117. Electrochemical analysis was also used to measure the corrosion inhibition efficiency of the synthesized sol-gel coating on AA 2024 alloy, and the hydrophobicity of the sol-gel corrosion-inhibiting coating composition could be analyzed using water contact angle measurements.

[0025] Sol-gel coating formulations can be synthesized using tetraethoxysilane (TEOS), vinyltriethoxysilane (VTS), 3-glycidoxypropyltrimethoxysilane (GPTMS), methyltrimethoxysilane (MTMS), acetic acid, zirconium isopropoxide, DMCT, and other similar ingredients. The shelf life of the corrosion-resistant coating composition of the present invention can be evaluated based on the settling of DMCT particles dispersed within the corrosion-inhibiting coating composition. In an exemplary example, it was observed that the DMCT particles in the B portion solution were not dissolved but completely dispersed in the solution, and no precipitation or settling was observed. The color of the solution or coating dispersion turned yellow. In the example, after adding the A portion composition to the B portion composition, the color of the solution remained unchanged. Moreover, after 30 minutes, some particles in some examples began to settle to the bottom due to gravity. However, once the solution was mixed with stirring, the particles became uniformly distributed, and the color intensity remained unchanged.

[0026] The developed sol-gel conversion coating yielded this corrosion-inhibiting coating, which remains transparent and has passed a 336-hour salt spray test on AA2024 plates according to ASTM B117. No corrosion products were observed on the surface of the corrosion-resistant coated AA2024 plates after 168 and 336 hours of salt spray exposure. The use of DMCT may affect the transparency and appearance of this sol-gel conversion coating on aluminum alloys, while still providing corrosion resistance without the need for chromium inhibitors. However, the presence of these DMCT particles may also cause a slight yellowing tint.

[0027] In some instances, corrosion inhibitor coating compositions or formulations may be applied to protect the substrate and other layers or portions of carrier 100 from environmental impacts. Figure 1AA schematic diagram of a vehicle 100 according to an embodiment is shown. As shown, vehicle 100 may include an aircraft. Vehicle 100 may also include, or alternatively include, other types of aircraft, such as helicopters, unmanned aerial vehicles (UAVs), spacecraft, or ships. In other embodiments, vehicle 100 may be or include cars, boats, or trains. In other embodiments, the systems and methods described below may be implemented not in a vehicle, but in a building. Vehicle 100 may include one or more lavatories (one shown: 110). Lavator 110 may include a sink 112, a toilet 114, and a sensor 116. Sensor 116 may sense / determine whether lavatories 110 are occupied (e.g., occupied by passengers) or unoccupied. For example, sensor 116 may be or include a motion sensor. Vehicle 100 may also include one or more kitchens or preparation rooms (one shown: 120). Kitchen 120 may include a sink 122, a dishwasher 124, and an ice maker 126. Corrosion inhibitor coating composition 128 may be applied to one or more outer surfaces or components of vehicle 100 to prevent or resist corrosion when exposed to a variety of harsh environmental conditions.

[0028] Figure 1B The application of the corrosion-inhibiting composition according to the present invention to a structural component, including a coating applied to an aerospace vehicle, is illustrated. The application of the coating composition or method of the present disclosure to an aerospace vehicle 100 is shown, wherein the coating composition of the present disclosure is coated on a vehicle substrate 130. An exploded view shows that the surface of the vehicle substrate 130 has a substrate surface layer 132 and a corrosion-inhibiting coating composition layer 134, thereby imparting corrosion resistance or corrosion inhibition to the surface of the substrate 130 and / or a structural component or portion of the vehicle. In one example, the application of the coating composition of the present disclosure relates to the outer surface of the aerospace vehicle 100. In this example, an additional coating, such as paint, coating, or other protective coating, may be applied over the corrosion-inhibiting coating composition layer 134. It should be noted that in some examples, the substrate surface layer 132 is optional.

[0029] Figure 1C This is an additional cross-sectional schematic diagram of an exemplary corrosion-inhibiting coating composition in a service environment according to the present invention. The environment may include articles or components of a carrier or other structure. In an exemplary example, a substrate 136 is shown having a corrosion-resistant coating composition 138 coated or deposited on the surface of the substrate 136. A formulation is also shown in which a primer layer 142 is applied over the corrosion-resistant coating composition 138 containing corrosion-inhibiting component 140, followed by a topcoat layer 144.

[0030] In examples, the substrate may be or include metals, polymers, polymer composites, or combinations thereof. In some embodiments, the substrate includes aluminum, titanium, steel, and alloys thereof, and in examples includes nickel-plated steel or a coating comprising one or more transition metals (including, but not limited to, scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, zinc, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, cadmium, or combinations thereof). In other examples, the article does not contain an adhesive or primer between the substrate and the corrosion inhibitor coating composition. In examples, the polymer composite may include one or more polymers, one or more reinforcing particles or fibers, or combinations thereof. The article may be or include components or parts of aerospace vehicles or watercraft, or the article may be or include its outer surface. Materials that can be used include aerospace alloys, such as composite aluminum and aluminum alloys, as well as other easily corroded metals used in aerospace applications. In examples, external components or separate coatings may be included or added to the surface of its corrosion inhibitor coating. The component corrosion inhibitor coating may also be used as a sealant for porous anodized surface layers on various passivated substrates. In this example, primer layer 142 may be or include epoxy resin, phenolic epoxy polyamine primer, or other polymeric aerospace primer, or primer for commercial aircraft applications as defined in BMS10-11, primer as defined in MIL-PRF-23377C, and may also include primer for fuel tanks. In this example, topcoat layer 144 may be or include polyurethane or polysiloxane topcoats commonly used in commercial aircraft applications.

[0031] In one example, a substrate is coated with a corrosion inhibitor coating composition disposed on the substrate surface. The corrosion inhibitor coating comprises 2,5-dimercapto-1,3,4-thiadiazole (DMCT), at least one active silane, and a catalyst. The at least one active silane includes tetraethoxysilane (TEOS), vinyltriethoxysilane (VTS), 3-glycidoxypropyltrimethoxysilane (GPTMS), or combinations thereof. This corrosion inhibitor coating composition does not contain chromium. The catalyst may include zirconium isopropoxide, acetic acid, dilute hydrochloric acid, etc. In this example, based on the total weight of the corrosion inhibitor coating composition, the amount of 2,5-dimercapto-1,3,4-thiadiazole (DMCT) is from about 0.1% to about 5.0%, or from about 0.1% to about 4%, or from about 0.1% to about 3.5% (wt%). The coating thickness of the corrosion inhibitor coating composition can be from about 30 nm to about 10 μm, from about 100 nm to about 5 μm, or from about 100 nm to about 2 μm.

[0032] Corrosion inhibitors can be organic or inorganic compounds that impart corrosion resistance to metals when at least a portion of them dissolve. For example, a corrosion inhibitor can be multiple corrosion inhibitor particles, such as multiple chemically reactive non-chromium corrosion inhibitor particles. Corrosion inhibitor particles can be thiol-containing corrosion inhibitor particles because they contain insoluble organic molecules containing thiols or sulfides.

[0033] In one instance, the term "non-chromium" as used herein refers to materials that do not contain chromium; for example, they may be chromium-free (VI). Corrosion inhibitors can be disulfide / dithiol compounds, such as insoluble thiol- or sulfide-containing organic molecules. Thiol- or sulfide-containing organic molecules can be polydisulfides, such as thiol-terminated polysulfides of dimercaptothiadiazole.

[0034] Corrosion inhibitors can be derived from crude non-chromium corrosion inhibitor particles, such as bulk non-chromium corrosion inhibitor particles formed according to known synthetic routes or available as commercial powders. In one example, the corrosion inhibitor comprises 2,5-dimercapto-1,3,4-thiadiazole (DMCT). Therefore, the crude corrosion inhibitor can be 5,5-dithiobis(1,3,4-thiadiazole-2(3H)-thione), Zn(DMCT)2, or Zn(bis-DMCT)2.

[0035] The preparation of corrosion inhibitor particles may include the precipitation of insoluble substances, for example, by dissolving a compound in an organic solvent and then precipitating the corrosion inhibitor from the solution by adding the dissolved compound to a non-solvent. For example, a compound such as the dimer bis-DMCT of DMCT can be dissolved in an organic solvent such as THF, and then the dissolved bis-DMCT can be added to water to precipitate crude corrosion inhibitor particles. Alternatively, the crude corrosion inhibitor may be derived from bis-DMCT (e.g., available from Vanderbilt Chemicals, LLC, Norwalk, Connecticut). 829) or Zn(DMCT)2 (e.g., available from Wayne Pigment Corporation in Milwaukee, Wisconsin). 1000 or 204) or a combination of both. In alternative examples, corrosion inhibitors may also include strontium aluminum polyphosphate hydrate (SAPP) (available from Heubach GmbH, Wrangellsheim, Germany). (Obtained via SAPP). Examples of corrosion inhibitors may include 2,5-dimercapto-1,3,4-thiadiazole (DMCT) from Alfa Aeser Chemicals and Acros Organics Chemicals, which can be dispersed or dissolved in ethanol or isopropanol, respectively, and can be used in the coating solutions or formulations described herein. Metal salts of DMCT, oligomers of DMCT, or other polymeric sources of DMCT may be used as alternatives.

[0036] The one or more corrosion inhibitor coating compositions may be, or include but are not limited to, one or more compounds containing at least one corrosion inhibitor, at least one active silane, or any combination thereof. Organosilanes are generally understood to be (but not necessarily limited to) multifunctional silicon-containing molecules containing reactive functional groups and one or more hydrolyzable alkoxy groups. Exemplary silanes may include, but are not limited to, bis(trimethoxysilylethyl)benzene, bis(triethoxysilylethyl)benzene, 3-acryloyloxypropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, allyltrimethoxysilane, tetraethyl orthosilicate (TEOS), vinyltriethoxysilane (VTS), 3-glycidoxypropyltrimethoxysilane (GPTMS), methyltrimethoxysilane (MTMS), or combinations thereof. Other exemplary glycidoxy-functional or epoxy-functionalized silanes may include, but are not limited to, glycidoxypropyltrialkoxysilanes (such as glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, etc.), 3-(2,3-epoxypropoxypropyl)methyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-(2,3-epoxypropoxypropyl)methyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, 8-glycidoxyoctyltrimethoxysilane, 1-(3-glycidoxypropyl)-1,1,3,3,3-pentaethoxy-1,3-disilpropane and combinations thereof. Exemplary mercaptofunctional silanes may include, but are not limited to, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 11-mercaptoundecyltrimethoxysilane, s-(octanoyl)mercaptopropyltriethoxysilane, (mercaptomethyl)methyldiethoxysilane, 3-mercaptopropylmethyldimethoxysilane, mercaptopropyltrialkoxysilane (such as mercaptopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane), mercaptoundecyltrimethoxysilane, (mercaptomethyl)methyldiethoxysilane, and combinations thereof. In exemplary examples of corrosion inhibitor coating compositions, when the composition contains more than one active silane, it is advantageous that the first active silane is different from the second active silane, allowing other organic functional groups to be added to the corrosion inhibitor coating composition, thereby providing other potentially reactive functional groups present in the corrosion inhibitor coating composition. Unbound by any particular theory, the chemical properties of other functional groups in corrosion inhibitor coating compositions can provide versatility or utility for corrosion inhibitor coating compositions, thus enabling them to be used in a wide range of applications targeting polymer formulation layers, substrates, or combinations thereof.

[0037] Based on the total weight of the corrosion inhibitor coating composition, the amount of the one or more silanes or organosilanes present can be from about 0.01 wt% to about 15 wt%. For example, based on the total weight of the corrosion inhibitor coating composition, the amount of the one or more organosilanes present can be from about 0.01 wt%, about 0.5 wt%, about 1 wt%, about 1.5 wt%, about 2 wt%, or from about 2.5 wt% to about 2.75 wt%, about 3 wt%, about 3.5 wt%, about 4 wt%, about 4.5 wt%, about 10.0 wt%, or about 20.0 wt%. In another example, based on the total weight of the corrosion inhibitor coating composition, the amount of the one or more organosilanes present can be from about 0.01 wt% to about 10.0 wt%, from about 1 wt% to about 8.0 wt%, from about 2.0 wt% to about 6.0 wt%, about 5 wt%, or about 5 wt%.

[0038] One or more organic solvents in a corrosion inhibitor coating composition may be capable of or configured to disperse, dissolve, solvate, or otherwise dissolve one or more substances or components of the corrosion inhibitor coating composition. One or more organic solvents in a corrosion inhibitor coating composition may also be capable of or configured to disperse, dissolve, solvate, or otherwise dissolve one or more substances, such as grease, oil, or debris, on a surface in contact with the corrosion inhibitor coating composition. For example, one or more organic solvents in a corrosion inhibitor coating composition may be capable of or configured to dissolve one or more components of the corrosion inhibitor coating composition. The one or more organic solvents may also be capable of or configured to prepare a surface for subsequent treatment or application of a sealant, coating, or other material to the same substrate as the corrosion inhibitor coating composition. For example, the one or more organic solvents may be capable of or configured to at least partially provide a cleaning treatment of the surface or substrate. It should be understood that any organic solvent capable of or configured to dissolve one or more components of the corrosion inhibitor coating composition and / or prepare a surface for subsequent treatment or application of a coating material or adhesive can be used.

[0039] The one or more organic solvents may be, or include but are not limited to, aliphatic hydrocarbons, aromatic compounds (e.g., aromatic hydrocarbons), halogenated hydrocarbons, nitrated hydrocarbons, ketones, amines, esters, alcohols, aldehydes, ethers, or combinations thereof.

[0040] Exemplary aliphatic hydrocarbons that can be used as one or more organic solvents may be, or include but are not limited to, n-pentane, n-hexane, n-octane, n-nonane, n-decane or their homologues, 2,2,4-trimethylpentane, etc., or any combination thereof.

[0041] Exemplary aromatic compounds that can be used as one or more organic solvents may be, but are not limited to, cyclohexane, benzene, toluene, ethylbenzene, xylene, tetrahydronaphthalene, hexafluoroxylene, or any combination thereof.

[0042] Exemplary halogenated hydrocarbons that can be used as one or more organic solvents may be, or include but are not limited to, chloroform, trichloroethylene, dichloromethane, or combinations thereof.

[0043] Exemplary ketone organic solvents may be, or include but are not limited to, acetone, methyl ethyl ketone (MEK), diethyl ketone, methyl acetone (MPK), diacetone, methyl isobutyl ketone (MIBK), cyclopentanone, cyclohexanone, methyl pentanone, N-methyl-2-pyrrolidone, diisobutyl ketone, acetophenone, etc., or combinations thereof.

[0044] Exemplary esters that can be used as one or more organic solvents may be, but are not limited to, methyl acetate, ethyl acetate, isopropyl acetate, n-butyl acetate, acetic acid solvent, or combinations thereof.

[0045] Exemplary alcohols that can be used as one or more organic solvents may be, or include but are not limited to, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, sec-butanol, n-pentanol, isopentanol, cyclohexanol, n-octanol, ethylene glycol, diethylene glycol, 1,2-propanediol, etc., or combinations thereof.

[0046] Exemplary aldehydes that can be used as one or more organic solvents may be, or include, furfural, etc.

[0047] Exemplary ethers that can be used as one or more organic solvents may be, or include but are not limited to, diethyl ether, isopropyl ether, butyl ether, methyl tert-butyl ether, 1,4-dioxane, tetrahydrofuran, oligomers of perfluoropolyethers (e.g., commercially available from Solvay, Houston, Texas). (Series), etc., or combinations thereof.

[0048] Some embodiments of the corrosion inhibitor coating compositions described herein may have very different viscosities, which can be adjusted according to their application methods. The amount of one or more organic solvents present in the corrosion inhibitor coating composition can vary considerably, which may directly affect the viscosity of the corrosion inhibitor coating composition. The corrosion inhibitor coating composition can be applied to a surface or between two substrates by brushing, air brushing, spraying, dripping, pouring, pipetting, wiping, etc. The amount of one or more organic solvents present can be determined at least in part by the target or desired viscosity of the corrosion inhibitor coating composition. Based on the total weight of the corrosion inhibitor coating composition, the amount of one or more organic solvents present in the corrosion inhibitor coating composition can be from about 75% by weight to about 99.5% by weight. For example, based on the total weight of the corrosion inhibitor coating composition, the amount of one or more organic solvents present in the corrosion inhibitor coating composition can be from about 75% by weight, about 80% by weight, about 85% by weight, or about 90% by weight to about 95% by weight, about 98% by weight, about 99% by weight, or about 99.5% by weight. In another example, based on the total weight of the corrosion inhibitor coating composition, the amount of one or more organic solvents present in the corrosion inhibitor coating composition may be from about 75% to about 99.5% by weight, from about 80% to about 99% by weight, from about 85% to about 95% by weight, or from about 85% to about 90% by weight. In other examples, the viscosity or consistency of the sol-gel coating formulation can be adjusted by changing the proportions of various organosilanes used in the formulation and the amount of solvent.

[0049] In one example, the shear viscosity of the corrosion inhibitor coating composition at a temperature of about 25°C can be from about 0.01 Pa·s to about 10 Pa·s. For example, the shear viscosity of the corrosion inhibitor coating composition at a temperature of about 25°C can be from about 0.01 Pa·s, about 2 Pa·s, about 4 Pa·s, or about 5 Pa·s to about 6 Pa·s, about 8 Pa·s, about 9 Pa·s, or about 10 Pa·s. In another example, the shear viscosity of the corrosion inhibitor coating composition at a temperature of about 25°C can be from about 0.01 Pa·s to about 10 Pa·s, about 2 Pa·s to about 8 Pa·s, or about 4 Pa·s to about 6 Pa·s. Measurements of the corrosion inhibitor coating composition can be performed at a shear rate of about 0.1 Hz to about 100 Hz at a temperature of about 25°C. The corrosion inhibitor coating composition is measured at a shear rate of about 0.1 to about 100 sec. -1 The viscosity at the shear rate can be from about 0.01 to about 10 Pa·s.

[0050] Corrosion inhibitor coating compositions may contain one or more catalysts. As used herein, the term "catalyst" may refer to any component, compound, or substance that can increase the rate of chemical reactions associated with the crosslinking or formation of the coating, but does not necessarily result in a permanent chemical change.

[0051] Based on the total weight of the corrosion inhibitor coating composition, the amount of the one or more catalysts present can be from about 0.1 wt% to about 10 wt%. For example, based on the total weight of the corrosion inhibitor coating composition, the amount of the one or more catalysts present can be from about 0.1 wt%, about 0.5 wt%, about 1 wt%, about 1.5 wt%, about 2 wt%, about 3 wt%, about 4 wt%, or about 5 wt% to about 6 wt%, about 6.5 wt%, about 7 wt%, about 8 wt%, about 9 wt%, or about 10 wt%. In another example, the amount of the one or more catalysts present can be from about 0.1 wt% to about 5 wt%, from about 0.5 wt% to about 2.5 wt%, or from about 0.5 wt% to about 1.0 wt%.

[0052] Example

[0053] Example 1: The corrosion-resistant (modified) conversion coating of Example 1 was prepared in two parts, namely Part A and Part B. Part A preparation involved adding glacial acetic acid (GAA, Sigma Aldrich) to zirconium propoxide (TPOZ, Sigma Aldrich) with stirring for 10 minutes. All glassware was ensured to be completely dry at this time to avoid the formation of zirconium hydroxide. Deionized water was added to the above GAA:TPOZ mixture and stirred for 10 minutes. The resulting solution remained translucent and was allowed to stand for two weeks to allow the solution to clarify. Part B preparation involved adding (3-glycidoxypropyl)trimethoxysilane (GPTMS, Sigma Aldrich) to tetraethyl orthosilicate (TEOS, Sigma Aldrich) and stirring for 10 minutes. Ethanol (Hymann) was added to the above GPTMS:TEOS mixture and stirred overnight (approximately 16 hours) to complete the hydrolysis and condensation reaction. 2,5-dimercapto-1,3,4-thiadiazole (DMCT, Alfa Aesar) was added to the Part B mixture and stirred for 10 minutes. Finally, while stirring vigorously, gradually add part A to part B.

[0054] Chemical Name molecular weight number of moles Weight in grams Part A Acetic acid 36.45 0.007 0.45 Zirconium propoxide 327.57 0.003 1 water 18 2.75 50

[0055] Table 1: Composition of Part A

[0056]

[0057] Table 2: Components of Part B

[0058] The weight percentage of DMCT (based on a total weight of 2% of the corrosion-inhibiting composition) is calculated taking into account the weight percentages of parts A and B. The shelf life of the developed corrosion-resistant coating was studied based on the settling behavior of the DMCT particles.

[0059] Coating application: The developed corrosion-resistant coating was applied to AA 2024 boards by spraying at different aging time intervals, namely 5 minutes, 30 minutes and 2 hours.

[0060] The coating was cured at room temperature for 24 hours and then subjected to a salt spray test. Evaluation of 2,5-dimercapto-1,3,4-thiadiazole revealed two color intensities due to its origin from two different brands, Acros Organics and Alfa Aesar. Fourier transform infrared spectroscopy (FTIR) confirming analysis showed that the peaks of the two chemicals were similar.

[0061] Storage periods of the corrosion-resistant Boegel using DMCT (Alfa Aesar) at different time intervals showed that the DMCT particles in Part B solution did not dissolve but were completely dispersed in the solution. No precipitation or sedimentation was observed. The solution color turned yellow. After adding Part A to Part B solution, the solution color remained unchanged. After 30 minutes, some particles began to settle to the bottom due to gravity. However, once mixed, the solution under stirring showed a uniform particle distribution and the color intensity remained unchanged. Storage periods of the corrosion-resistant coating using DMCT (Acros Organics) at different time intervals showed that the DMCT particles in Part B solution also completely dissolved. No precipitation or sedimentation was observed. After adding Part A solution to Part B, the solution became translucent. After stirring for 10 minutes, the solution became clear. The developed solution was used for coating on AA 2024 plates.

[0062] Figures 2A to 2C The images are photographs of the exemplary coating according to Embodiment 1 of the present invention after application, after a 168-hour salt spray test, and after a 336-hour salt spray test. Figure 2A The evaluation of the various coatings shown is prior to the salt spray test, demonstrating that the corrosion-resistant coatings are transparent and uniform on the AA 2024 plates. From left to right, the plates show photographic examples of Example 1 mixed and left to stand for 5 minutes (two samples), 30 minutes (two samples), and 2 hours (two samples). Figure 2B The photograph shown depicts the scene after a 168-hour salt spray test. Figure 2A The same six samples were used. After 168 hours of salt spray exposure, no corrosion products were observed on the surface of the corrosion-resistant coated AA 2024 plate. Figure 2C The photograph shown depicts the aftermath of a 336-hour salt spray test. Figure 2A The same six samples were used. After 336 hours of salt spray exposure, no corrosion products were observed on the surface of the corrosion-resistant coated AA 2024 plate.

[0063] Example 2: Sol-gel coating formulation containing TEOS, VTS, and DMCT (TEOS:VTS(2:1)) A mixture of TEOS(2) and VTS(1) was added to a reaction flask and stirred for 10 minutes with a magnetic stirrer. Ethanol was added as a solvent and stirred for another 10 minutes. Distilled water was added over 10 minutes at room temperature with vigorous stirring. Complete hydrolysis was ensured by acid catalysis through the dropwise addition of 1N hydrochloric acid solution. The final solution was vigorously stirred at room temperature (or at approximately 25°C) for 16 hours to ensure the hydrolysis and condensation of the silica network. Finally, 1% by weight of DMCT was added to the above sol-gel coating. The sol-gel solution was sprayed onto a clean AA2024 substrate at varying intervals and cured at room temperature. The cured coating was analyzed by salt spray testing according to ASTM B117.

[0064]

[0065] Table 3: Composition of Example 2

[0066] Storage periods of DMCT (Alfa Aesar) TEOS and VTS sol-gel coatings applied at different time intervals showed that the DMCT particles in the sol-gel solution did not dissolve but were completely dispersed. The solution turned yellow. No precipitation was observed. After 30 minutes, the DMCT particles began to settle to the bottom due to gravity. However, once mixed, the stirred solution showed a uniform particle distribution and the color intensity remained unchanged. The storage period of the sol-gel solution containing DMCT particles was determined by applying the coating at three different time intervals: 5 minutes, 30 minutes, and 2 hours.

[0067] Figures 3A to 3C The images are photographs of the exemplary coating according to Embodiment 2 of the present invention after application, after a 168-hour salt spray test, and after a 336-hour salt spray test. Figure 3A The evaluation of the various coatings shown was prior to the salt spray test, demonstrating that the corrosion-resistant coatings were clear and uniform on the AA 2024 plates. From left to right, the plates show photographic examples of Example 2 mixtures and standing for 5 minutes (two samples), 30 minutes (two samples), and 2 hours (two samples). The TEOS and VTS+DMCT sol-gel coatings were clear and uniform on the AA 2024 plates. Figure 3B The photograph shown depicts the scene after a 168-hour salt spray test. Figure 3A The same six samples were used. After 168 hours of salt spray exposure, no corrosion products were observed on the surface of the corrosion-resistant coated AA 2024 plate. Figure 3C The photograph shown depicts the aftermath of a 336-hour salt spray test. Figure 3AThe same six samples were used. After 336 hours of salt spray exposure, no corrosion products were observed on the surface of the corrosion-resistant coated AA 2024 plate.

[0068] Example 3: Sol-gel coating formulation containing TEOS, MTMS & DMCT (TEOS:MTMS(2:1)) A mixture of TEOS(2) and MTMS(1) was added to a reaction flask and stirred for 10 minutes on a magnetic stirrer. Ethanol was added as a solvent and stirred for another 10 minutes. Distilled water was added over 10 minutes at room temperature under vigorous stirring. Complete hydrolysis was ensured by acid-catalyzed reaction through the addition of 1N hydrochloric acid solution dropwise. The final solution was vigorously stirred at room temperature for 16 hours to ensure the hydrolysis and condensation of the silica network. Finally, 2% by weight of DMCT was added to the above sol-gel coating, and the shelf life was determined. The sol-gel solution was sprayed onto a clean AA 2024 substrate at different intervals and cured at room temperature. The cured coating was analyzed by salt spray study according to ASTM B117.

[0069]

[0070] Table 4: Composition of Example 3

[0071] Storage periods of TEOS and MTMS sol-gel coatings containing DMCT at different time intervals showed that the DMCT particles in the TEOS and MTMS sol-gel solutions did not dissolve but were completely dispersed. The solution turned yellow. No precipitation was observed. After 30 minutes, the particles began to settle to the bottom due to gravity. However, once mixed, the stirred solution showed a uniform particle distribution while maintaining the same color intensity. The storage period of the sol-gel solution containing DMCT particles was determined by coating at three different time intervals: 5 minutes, 30 minutes, and 2 hours.

[0072] Figures 4A to 4C The images are photographs of the exemplary coating according to Embodiment 3 of the present invention after application, after a 168-hour salt spray test, and after a 336-hour salt spray test. Figure 4A The evaluation of the various coatings shown was prior to the salt spray test, demonstrating that the corrosion-resistant coatings were transparent and uniform on the AA 2024 plates. From left to right, the plates show photographic examples of Example 3 mixtures and standing for 5 minutes (two samples), 30 minutes (two samples), and 2 hours (two samples). Figure 4B The photograph shown depicts the scene after a 168-hour salt spray test. Figure 4A The same six samples were used. After 168 hours of salt spray exposure, no corrosion products were observed on the surface of the corrosion-resistant coated AA 2024 plate. Figure 4CThe photograph shown depicts the aftermath of a 336-hour salt spray test. Figure 4A The same six samples were used. After 336 hours of salt spray exposure, no corrosion products were observed on the surface of the corrosion-resistant coated AA 2024 plate.

[0073] Example 4: Sol-gel coating formulation containing TEOS, GPTMS & DMCT (TEOS:GPTMS(2:1)) A mixture of TEOS(2) and GPTMS(1) was added to a reaction flask and stirred for 10 minutes with a magnetic stirrer. Ethanol was added as a solvent and the solution was stirred for another 10 minutes. Distilled water was added over 10 minutes at room temperature with vigorous stirring. Hydrolysis was ensured by acid catalysis through the addition of 1N hydrochloric acid solution dropwise. The final solution was vigorously stirred at room temperature for 16 hours to ensure the hydrolysis and condensation of the silica network. Finally, 2% by weight of DMCT was added to the above sol-gel coating. The sol-gel solution was sprayed onto a clean AA 2024 substrate at different intervals and cured at room temperature. The cured coating was analyzed by salt spray study according to ASTM B117.

[0074]

[0075] Table 5: Composition of Example 4

[0076] Storage period assessment of TEOS and GPTMS sol-gel coatings containing DMCT at different time intervals showed that the DMCT particles in the TEOS and GPTMS sol-gel solutions did not dissolve but were completely dispersed. The solution turned yellow. No precipitation was observed. After 30 minutes, the particles began to settle to the bottom due to gravity. Once mixed, the stirred solution showed uniform particle distribution and maintained color intensity. The storage period of the sol-gel solution containing DMCT particles was determined by coating at three different time intervals: 5 minutes, 30 minutes, and 2 hours.

[0077] Figures 5A to 5C The images are photographs of the exemplary coating according to Embodiment 4 of the present invention after application, after a 168-hour salt spray test, and after a 336-hour salt spray test. Figure 5A The evaluation of the various coatings shown was prior to the salt spray test, demonstrating that the corrosion-resistant coatings were transparent and uniform on the AA 2024 plates. From left to right, the plates show photographic examples of Example 4 mixtures and standing for 5 minutes (two samples), 30 minutes (two samples), and 2 hours (two samples). Figure 5B The photograph shown depicts the scene after a 168-hour salt spray test. Figure 5AThe same six samples were used. After 168 hours of salt spray exposure, no corrosion products were observed on the surface of the corrosion-resistant coated AA 2024 plate. Figure 5C The photograph shown depicts the aftermath of a 336-hour salt spray test. Figure 5A The same six samples were used. Due to the loss of salt solution, trace corrosion products were observed at the edges of the TEOS, MTMS sol-gel coated AA 2024 plates after 336 hours of salt spray exposure. No corrosion was observed in the middle section.

[0078] Generally, the synthesis of sol-gel coatings used in the corrosion-inhibiting coating compositions described herein involves the following steps:

[0079] Hydrolysis: Different ethoxysilanes, as well as the methoxysilanes in the examples, were used for sol-gel synthesis. In the hydrolysis step, all ethoxy / ethyl (or methoxy / methyl) molecules were hydrolyzed in the presence of water to produce hydroxysilane molecules.

[0080] Condensation: In the condensation step, water condensation and / or alcohol condensation occur under the action of a catalyst, thereby forming cross-linked siloxanes in which all silane molecules combine together to form Si-O-Si bonds.

[0081] Polymerization: In the polymerization step, all siloxane molecules react together in the presence of heat or light (e.g., a photoinitiator (HV)) and develop into a chain structure. Organic groups or polymerizable groups are required for polymerization.

[0082] Other additives: As an example, 2,5-dimercapto-1,3,4-thiadiazole or other additives can be added to the sol-gel synthesis, which can react with groups in the siloxane molecule or be suspended in the siloxane network and promote the corrosion resistance of the coating.

[0083] Although this teaching has been described with respect to one or more embodiments, changes and / or modifications may be made to the illustrated examples without departing from the spirit and scope of the appended claims. For example, it is understood that although the process is described as a series of actions or events, this teaching is not limited to the order of these actions or events. Some actions may occur in a different order and / or simultaneously with other actions or events not described herein. Furthermore, not all process stages require the implementation of one or more aspects or embodiments of this teaching. It is understood that structural objects and / or processing stages may be added, or existing structural objects and / or processing stages may be removed or modified. Furthermore, one or more actions described herein may be performed as one or more separate actions and / or stages. Additionally, when the terms “comprising,” “having,” “containing,” or variations thereof are used in the detailed description and claims, these terms are intended to be inclusive in a manner similar to the term “comprising.” The term “at least one” is used to indicate that one or more of the listed items may be selected. Furthermore, in the discussion and claims herein, the term "on" (i.e., one on top of another) regarding two materials implies at least some contact between the materials, while "above" means the materials are close together, but one or more other intermediate materials may be present, making contact possible but not required. The use of "on" or "above" herein does not imply any directionality. The term "conformal" describes a coating material in which the angle of the underlying material is maintained by a conformal material. The term "about" indicates that the listed values ​​may be varied, as long as such variation does not result in a process or structure inconsistent with the illustrated embodiment. The terms "joint," "connected," and "connected with" mean "directly connected with" or "connected with" through one or more intermediate elements or members. Finally, the terms "exemplary" or "illustrative" indicate that the description is used as an example and not implying that it is ideal. Other embodiments of the teachings will be apparent to those skilled in the art upon consideration of this specification and practice of the disclosure herein. The specification and examples should be considered merely exemplary, and the true scope and spirit of the teachings are indicated by the appended claims.

Claims

1. A corrosion inhibitor coating composition (128) comprising: Corrosion inhibitor containing 2,5-dimercapto-1,3,4-thiadiazole (DMCT); At least one active silane; and catalyst.

2. The corrosion inhibitor coating composition (128) as claimed in claim 1, wherein, The at least one active silane includes tetraethoxysilane (TEOS), or The at least one active silane includes vinyltriethoxysilane (VTS), 3-glycidoxypropyltrimethoxysilane (GPTMS), methyltrimethoxysilane (MTMS), or a combination thereof.

3. The corrosion inhibitor coating composition (128) as described in claim 1 or 2, wherein, The corrosion inhibitor coating composition (128) does not contain chromium, and / or The catalyst includes zirconium isopropoxide, and / or The catalyst includes acetic acid.

4. The corrosion inhibitor coating composition (128) according to any one of claims 1 to 3, wherein, The 2,5-dimercapto-1,3,4-thiadiazole (DMCT) is present in an amount of about 0.1% to about 5.0% of the total weight of the corrosion inhibitor coating composition (128), and / or Wherein, the at least one active silane comprises a first active silane and a second active silane, and the weight ratio of the first active silane to the second active silane is from about 0.5:1 to about 3:1, and / or The corrosion inhibitors also include thiadiazole, benzotriazole, imidazole, or combinations thereof.

5. An article comprising: Substrate (130, 136); A corrosion inhibitor coating composition (128) disposed on the surface of the substrates (130, 136), the corrosion inhibitor coating composition (128) comprising: 2,5-Dimercapto-1,3,4-thiadiazole (DMCT); At least one active silane; and catalyst; in, The at least one active silane includes tetraethoxysilane (TEOS), vinyltriethoxysilane (VTS), 3-glycidoxypropyltrimethoxysilane (GPTMS), or a combination thereof.

6. The article of claim 5, wherein, The corrosion inhibitor coating composition (128) does not contain chromium, and / or The catalyst includes zirconium isopropoxide, acetic acid, hydrochloric acid, or a combination thereof, and / or The 2,5-dimercapto-1,3,4-thiadiazole (DMCT) is present in an amount of about 0.1% to about 5.0% of the total weight of the corrosion inhibitor coating composition (128).

7. The article of claim 5 or 6, wherein, The corrosion inhibitor coating composition (128) has a thickness of about 30 nm to about 10 μm, and / or The substrates (130, 136) include metals, polymers, polymer composites, or combinations thereof, and / or The substrate (130, 136) includes nickel-plated steel.

8. The article of manufacture according to any one of claims 5 to 7, wherein, There is no adhesive or primer between the substrate (130, 136) and the corrosion inhibitor coating composition (128), and / or The product is a component or part of an aerospace vehicle (100) or a water vehicle (100).

9. A method for providing a corrosion inhibitor coating, comprising: A corrosion inhibitor coating composition (128) comprising 2,5-dimercapto-1,3,4-thiadiazole (DMCT), at least one active silane, a catalyst, and a solvent is formed; The corrosion inhibitor coating composition (128) is applied to the surface of the substrate (130, 136); and The corrosion inhibitor coating composition (128) is exposed to the curing temperature.

10. The method of providing a corrosion inhibitor coating as described in claim 9, wherein: The thickness of the corrosion inhibitor coating composition (128) is from about 100 nm to about 10 μm; and The curing temperature is from about 15°C to about 150°C.

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