Chrome-free corrosion resistant sol-gel conversion coatings

Abstract

To provide a corrosion inhibitor coating composition.SOLUTION: A corrosion inhibitor coating composition includes a corrosion inhibitor such as 2,5-dimercapto-1,3,4-thiadiazole (DMCT), at least one reactive silane, and a catalyst. The reactive silane may include tetraethoxysilane (TEOS), vinyltriethoxysilane (VTS), 3-glycidoxypropyltrimethoxysilane (GPTMS), methyltrimethoxysilane (MTMS), or a combination thereof. The corrosion inhibitor coating composition does not include chromium. The catalyst may include zirconium isopropoxide or acetic acid. The corrosion inhibitor may also include a thiadiazole, a benzotriazole, an imidazole, or a combination thereof. An article to which a corrosion inhibitor coating treatment is applied and a method of providing a corrosion inhibitor coating treatment are also disclosed.SELECTED DRAWING: None

Description

[Technical Field]

[0001] FIELD OF THE INVENTION

[0001] The present invention relates generally to chromium-free corrosion-inhibiting coatings, and more particularly to chromium-free corrosion-inhibiting coatings comprising sol-gels. [Background technology]

[0002] Chromium-containing 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 aircraft manufacturing. In recent years, the use of chromium conversion coatings has been restricted by global regulations. New organic corrosion inhibitor molecules have been developed that can be used as a replacement for chromium in some applications. These organic corrosion inhibitor molecules must be reacted with a multifunctional resin to produce a durable coating containing these inhibitors. In some coating processes, the inhibitors can be added or applied directly to panels found on vehicles or aircraft. However, in such cases, although the corrosion inhibitor is dispersed within the coating, it may not adhere well to the substrate panel or to a primer or epoxy coating previously applied to the substrate or panel.

[0003]

[0003] Therefore, cross-linking may be required between the coating molecules and the inhibitor within the inhibitor coating, and this reaction takes time. For example, some epoxy-based systems are not sufficiently reactive with the molecules of these organic-based corrosion inhibitor systems, and the reaction required for cross-linking does not proceed within the constraints of possible application methods. For example, high temperatures and long reaction times are required to achieve complete reaction and provide adequate coating properties and adhesion.

[0004]

[0004] Therefore, there is a need to provide corrosion-inhibiting compositions that have facile reactions that proceed within acceptable process limits while providing acceptable or improved adhesion and corrosion inhibition. In particular, chromate conversion coatings are needed in non-chromate primer systems to meet adhesion promotion and corrosion resistance requirements near metal surfaces. Summary of the Invention

[0005]

[0005] The following presents a simplified summary in order to provide a basic understanding of some aspects of one or more embodiments of the present teachings. This summary is not an extensive overview, and it is not intended to identify key or critical elements of the present teachings or to delineate the scope of the present disclosure. Rather, its primary purpose is merely to present one or more concepts in a simplified form as a prelude to the more detailed description that is presented later.

[0006]

[0006] A corrosion inhibitor coating composition is disclosed. The corrosion inhibitor coating composition contains a corrosion inhibitor, such as 2,5-dimercapto-1,3,4-thiadiazole (DMCT). The composition also contains at least one reactive silane and a catalyst. In some embodiments, the at least one reactive silane includes tetraethoxysilane (TEOS). The at least one reactive silane may include vinyltriethoxysilane (VTS), 3-glycidyloxypropyltrimethoxysilane (GPTMS), methyltrimethoxysilane (MTMS), or a combination thereof. The corrosion inhibitor coating composition is chromium-free. The catalyst may include 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% by total weight of the corrosion inhibitor coating composition. The at least one reactive silane may comprise a first reactive silane and a second reactive silane, wherein the weight ratio of the first reactive silane to the second reactive silane is from about 0.5: 1 to about 3: 1. The corrosion inhibitor may further comprise a thiadiazole, a benzotriazole, an imidazole, or a combination thereof.

[0007]

[0007] An article is disclosed. The article includes a substrate and a corrosion inhibitor coating composition disposed on the surface of the substrate. The composition may include 2,5-dimercapto-1,3,4-thiadiazole (DMCT), at least one reactive silane, and a catalyst. The at least one reactive silane may include tetraethoxysilane (TEOS), vinyltriethoxysilane (VTS), 3-glycidyloxypropyltrimethoxysilane (GPTMS), or a combination thereof. Some embodiments of the article include those in which the corrosion inhibitor coating composition is chromium-free. The catalyst may include 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% by total weight of the corrosion inhibitor coating composition. The corrosion inhibitor coating composition may have a thickness of about 100 nm to about 10 μm. The substrate may comprise a metal, a polymer, a polymer composite, or a combination thereof. The article may include an article where there is no adhesive or primer between the substrate and the corrosion inhibitor coating composition. The article is a component or part of an aerospace or marine vehicle.

[0008] A method for applying a corrosion inhibitor coating is disclosed, the method comprising forming a corrosion inhibitor coating composition comprising 2,5-dimercapto-1,3,4-thiadiazole (DMCT), at least one reactive 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 can include those in which the thickness of the applied corrosion inhibitor coating composition is from about 30 nm to about 10 μm and the curing temperature is from about 15° C. to about 150° C.

[0009]

[0009] The above-described features, functions and advantages can be realized individually in various embodiments and can also be combined in other embodiments, further details of which can be understood by reference to the following description.

[0010]

[0010] The accompanying drawings, which are incorporated into and constitute part of this specification, illustrate embodiments of the teachings of the present invention and, together with the following description, explain the principles of the present disclosure. [Brief explanation of the drawings]

[0011] [Figure 1A]

[0011] FIG. 1 is a schematic diagram of a vehicle according to the present disclosure. [Figure 1B]

[0012] 1 illustrates an example of an aerospace vehicle application of a structural component to which a corrosion-inhibiting composition according to the present disclosure has been applied. [Figure 1C]

[0013] 1 shows an exploded view of a structural component including a corrosion-inhibiting composition according to the present disclosure applied to an aerospace vehicle. [Figure 1D]

[0014] 2A-2C are additional cross-sectional schematic views of exemplary corrosion-inhibiting coating compositions in use according to the present disclosure. [Figure 2A]

[0015] 1 is a photograph of the exemplary coating of Example 1 after coating treatment according to the present disclosure. [Figure 2B] 1 is a photograph of an exemplary coating of Example 1 after 168 hours of salt spray testing according to the present disclosure. [Figure 2C] 1 is a photograph of an exemplary coating of Example 1 after 336 hours of salt spray testing according to the present disclosure. [Figure 3A]

[0016] 1 is a photograph of an exemplary coating of Example 2 after coating treatment according to the present disclosure. [Figure 3B] 1 is a photograph of an exemplary coating of Example 2 after 168 hours of salt spray testing according to the present disclosure. [Figure 3C] 1 is a photograph of an exemplary coating of Example 2 after 336 hours of salt spray testing according to the present disclosure. [Figure 4A]

[0017] 1 is a photograph of an exemplary coating of Example 3 after coating treatment according to the present disclosure. [Figure 4B] 1 is a photograph of an exemplary coating of Example 3 after 168 hours of salt spray testing according to the present disclosure. [Figure 4C] 1 is a photograph of an exemplary coating of Example 3 after 336 hours of salt spray testing according to the present disclosure. [Figure 5A]

[0018] 1 is a photograph of an exemplary coating of Example 4 after coating treatment according to the present disclosure. [Figure 5B] 1 is a photograph of an exemplary coating of Example 4 after 168 hours of salt spray testing according to the present disclosure. [Figure 5C] 1 is a photograph of an exemplary coating of Example 4 after 336 hours of salt spray testing according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012]

[0019] It should be noted that some details in the drawings have been simplified and are drawn for the purpose of facilitating understanding of the present disclosure rather than maintaining strict structural accuracy, detail, and scale.

[0013]

[0020] DETAILED DESCRIPTION OF THE INVENTION Reference will now be made in detail to exemplary embodiments of the present teachings, as illustrated in the accompanying drawings. Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.

[0014]

[0021] As used herein, "free" or "substantially free" of a material can refer to a composition, component, or phase in which the material is present in an amount of 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.%, based on the total weight of the composition, component, or phase.

[0015]

[0022] Furthermore, all numerical values ​​are "about" or "approximately" the stated value, taking into account experimental error and variations that one of ordinary skill in the art can expect. All numerical values ​​and ranges disclosed herein should be understood to be approximate. The terms "about" or "substantial" and "substantially" or "approximately" in connection with a quantity or measurement mean that the stated characteristic, parameter, or value need not be achieved exactly. Rather, deviations or variations (including, for example, tolerances, measurement errors, limits of measurement accuracy, and other factors known to those of ordinary skill in the art) may occur in amounts that do not eliminate the effect intended to be brought about by the characteristic. As used herein, "about" means within ±5% of the stated target, maximum, or minimum value.

[0016]

[0023] All references cited herein are incorporated by reference in their entirety. In the event of a conflict in definitions between the present disclosure and a reference, the definitions in the present disclosure shall control.

[0017]

[0024] In the examples of the present disclosure, 2,5-dimercapto-1,3,4-thiadiazole (DMCT) is a corrosion inhibitor that can be used as a substitute for chromium corrosion inhibitors in sol-gel conversion coating compositions used as corrosion-inhibiting coatings. This disclosure describes methods and formulations for sol-gel conversion coating processes that improve corrosion resistance and promote adhesion by reducing the use of environmentally harmful coatings in aircraft or marine application programs. The disclosed approach can reduce the steps involved in outer layer coating processes and minimize the potentially harmful effects caused by chromium. The developed sol-gel conversion coatings have been pot-life tested with DMCT and their corrosion resistance performance evaluated using salt spray testing according to ASTM B117, as described below.

[0018]

[0025] The sol-gel-based corrosion-inhibiting composition was applied as a thin film to cleaned aluminum alloy (AA 2024) panels and allowed to cure at room temperature. The developed coating was transparent and passed a 336-hour salt spray test on AA 2024 panels according to ASTM B117 standard. Electrochemical analysis can also be used to measure the corrosion-inhibiting effect of the synthesized sol-gel coating on AA 2024 alloy, and water contact angle measurements can be used to analyze the hydrophobicity of the sol-gel-based corrosion-inhibiting coating composition.

[0019]

[0026] Sol-gel coating formulations can be synthesized using tetraethyl orthosilicate (TEOS), vinyltriethoxysilane (VTS), 3-glycidyloxypropyltrimethoxysilane (GPTMS), methyltrimethoxysilane (MTMS), acetic acid, zirconium isopropoxide, DMCT, and other similar components. The pot life of the corrosion-resistant coating compositions of the present disclosure can be evaluated based on the settling of DMCT particles dispersed within the corrosion-inhibiting coating composition. In a typical example, the DMCT particles in the Part B solution were completely dispersed in the solution without dissolution, and no settling or sedimentation was observed. The color of the solution or coating dispersion changed to yellow. For example, the color of the solution did not change after adding the Part A composition to the Part B composition. In some examples, the particles began to settle to the bottom due to gravity after 30 minutes. However, when the solution was mixed under agitation, the particles were uniformly dispersed and the color intensity was maintained.

[0020]

[0027] The developed sol-gel conversion coatings resulting in the corrosion-inhibiting coatings of the present invention remained transparent and passed a 336-hour salt spray test on AA 2024 panels in accordance with ASTM B117. No corrosion products were observed on the surface of the corrosion-resistant AA 2024 panels after either 168 hours or 336 hours of salt spray exposure. The use of DMCT can affect the transparency and appearance of such sol-gel conversion coatings on aluminum alloys while providing corrosion resistance without the need for chromium inhibitors. However, the use of DMCT can also result in a slight yellowish tint due to the presence of these DMCT particles.

[0021]

[0028] In some examples, the corrosion inhibitor coating composition or formulation thereof may be applied to protect a substrate and other layers or portions of a vehicle 100 from the environment. FIG. 1A shows a schematic diagram of a vehicle 100 according to one embodiment. As shown, the vehicle 100 may include an aircraft. The vehicle 100 may include or be substituted for other types of aircraft, such as a helicopter, an unmanned aerial vehicle (UAV), a spacecraft, or a marine vessel. In other embodiments, the vehicle 100 may be or include an automobile, a watercraft, a train, or the like. In still other embodiments, the systems and methods described below may not be implemented in a vehicle, but may be implemented in a building. The vehicle 100 may include one or more restrooms (one 110 is shown). The restroom 110 may include a sink 112, a toilet 114, and a sensor 116. The sensor 116 may detect / determine whether the restroom 110 is occupied (e.g., by a passenger) or vacant. For example, sensor 116 may be or may include a motion sensor. Vehicle 100 may also include one or more kitchens or galleys (one shown: 120). Kitchen 120 may include a sink 122, a dishwasher 124, and an ice maker 126. A corrosion inhibitor coating composition 128 may be applied to one or more exterior surfaces or components of vehicle 100 for corrosion prevention or corrosion resistance when exposed to a variety of harsh environmental conditions.

[0022]

[0029] FIG. 1B illustrates an example application of a structural component to an aerospace vehicle having a corrosion-inhibiting composition according to the present disclosure applied thereto. The application of the coating composition or coating method of the present disclosure is illustrated in an aerospace vehicle 100, with a vehicle substrate 130 having a coating composition of the present disclosure applied thereto. In exploded view 1C, vehicle substrate surface 130 is illustrated, including a substrate surface layer 132 and a corrosion inhibitor coating composition layer 134, thereby providing corrosion resistance or corrosion inhibition to the surface of substrate 130 or a structural component or portion thereof of the vehicle. By way of example, application of the coating composition of the present disclosure is directed to the exterior surface of aerospace vehicle 100. Additional coating layers, such as paints, coatings, or other protective coatings, may be applied over corrosion inhibitor coating composition layer 134. It should be noted that substrate surface layer 132 is optional in certain examples.

[0023]

[0030] 1D is an additional cross-sectional schematic view of an exemplary corrosion-inhibiting coating composition according to the present disclosure in a context of use, which may include an article or component of a vehicle or other structure. By way of example, a substrate 136 is shown having a corrosion-resistant coating composition 138 applied or deposited thereon. Furthermore, a primer layer 142 is applied over the corrosion-resistant coating composition 138, which includes a corrosion inhibitor component 140, and a topcoat 144 formulation is applied to the primer layer 142.

[0024]

[0031] The substrate may include, for example, a metal, a polymer, a polymer composite, or a combination thereof. In certain examples, the substrate includes aluminum, titanium, steel, and alloys thereof, such as nickel-plated steel or plating containing 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 include an adhesive or primer between the substrate and the corrosion inhibitor coating composition. Illustratively, the polymer composite may include one or more polymers, one or more reinforcing particles or fibers, or a combination thereof. The article may be or include a component or part of, or the outer surface of, an aerospace or marine vehicle. Materials including aerospace alloys, such as clad aluminum and aluminum alloys, as well as other corrosion-prone metals used in aerospace applications, may be used. Illustratively, external components or stand-alone coatings can be included or added to the surface of the corrosion-inhibiting coating. The component corrosion-inhibiting coating can also be used as a sealant for porous anodic oxide finishes on various passive substrates. Illustratively, the primer 142 layer can include an epoxy, phenolic epoxy-polyamine primer, or other polymeric aerospace primer, or a BMS 10-11 compliant primer, MIL-PRF-23377 Class C compliant primer, or even a fuel tank primer used in commercial aircraft applications. Illustratively, the topcoat 144 can be or include a polyurethane or polysiloxane-based topcoat commonly used in commercial aircraft applications.

[0025]

[0032] Illustratively, a substrate is coated with a corrosion inhibitor coating composition disposed on the surface of the substrate, the corrosion inhibitor coating composition comprising 2,5-dimercapto-1,3,4-thiadiazole (DMCT), at least one reactive silane, and a catalyst, the at least one reactive silane comprising tetraethoxysilane (TEOS), vinyltriethoxysilane (VTS), 3-glycidyloxypropyltrimethoxysilane (GPTMS), or a combination thereof. The corrosion inhibitor coating composition is chromium-free. The catalyst may comprise zirconium isopropoxide, acetic acid, dilute hydrochloric acid, or the like. Illustratively, the 2,5-dimercapto-1,3,4-thiadiazole (DMCT) is present in an amount of about 0.1% to about 5.0%, or about 0.1% to about 4%, or about 0.1% to about 3.5% by weight, based on the total weight of the corrosion inhibitor coating composition. The applied thickness of the corrosion inhibitor coating composition can be from about 30 nanometers to about 10 micrometers, from about 100 nanometers to about 5 micrometers, or from about 100 nanometers to about 2 micrometers.

[0026]

[0033] The corrosion inhibitor may be an organic or inorganic compound that, when at least a portion of it dissolves, provides corrosion resistance to the metal. For example, the corrosion inhibitor may be a plurality of corrosion inhibitor particles, such as a plurality of chemically reactive, non-chromium corrosion inhibitor particles. The corrosion inhibitor particles may be thiol-containing corrosion inhibitor particles, since they contain sparingly soluble thiol- or sulfide-containing organic molecules.

[0027]

[0034] In some instances, "chromium-free" as used herein may refer to a material that is chromium-free, e.g., does not contain hexavalent chromium. The corrosion inhibitor may be a disulfide / dithiol compound, e.g., an insoluble thiol- or sulfide-containing organic molecule. The thiol- or sulfide-containing organic molecule may be a polydisulfide, such as a mercaptan-terminated polysulfide of dimercaptothiadiazole.

[0028]

[0035] The corrosion inhibitor particles may 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 commercially available powders. In one example, the corrosion inhibitor particles include 2,5-dimercapto-1,3,4-thiadiazole (DMCT). Thus, the crude corrosion inhibitor can be 5,5-dithiobis-(1,3,4-thiadiazole-2(3H)-thione), Zn(DMCT)2, or Zn(bis-DMCT)2.

[0029]

[0036] Preparation of corrosion-inhibiting particles may involve precipitation of an insoluble species, such as dissolving the compound in an organic solvent and adding the dissolved compound to a non-solvent to precipitate the corrosion inhibitor in solution. For example, a compound such as bis-DMCT, a dimer of DMCT, can be dissolved in an organic solvent such as THF, and 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., VANLUBE® 829, available from Vanderbilt Chemicals, Norwalk, Connecticut) or Zn(DMCT)2 (e.g., INHIBICOR® 1000 or WAYNCOR® 204, available from Wayne Pigment, Milwaukee, Wisconsin), or a combination of both. In another example, the corrosion inhibitor may include strontium aluminum polyphosphate hydrate (SAPP) (available as HEUCOPHOS® SAPP from Heubach GmbH, Langelsheim, Germany). Examples of corrosion inhibitors 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 isopropyl alcohol, respectively, and used in the coating solutions or formulations described herein. Metal salts of DMCT, oligomers of DMCT, or other polymeric DMCT sources can be used as alternatives.

[0030]

[0037] The one or more corrosion inhibitor coating compositions may be or include at least one compound, including, but not limited to, at least one corrosion inhibitor, at least one reactive silane, or any combination thereof. Organosilanes are generally understood to be polyfunctional silicon-containing molecules containing a reactive functional group and one or more hydrolyzable alkoxy groups, but are not limited thereto. Exemplary silanes may include, but are not limited to, bis(trimethoxysilylethyl)benzene, bis(triethoxysilylethyl)benzene, 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, aminopropyltrimethoxysilane, vinyltrimethoxysilane, allyltrimethoxysilane, tetraethylorthosilicate (TEOS), vinyltriethoxysilane (VTS), 3-glycidyloxypropyltrimethoxysilane (GPTMS), methyltrimethoxysilane (MTMS), or combinations thereof. Other exemplary glycidyloxy- or epoxy-functional silanes may include, but are not limited to, glycidyloxypropyltrialkoxysilanes (e.g., glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, etc.), 3-(2,3-epoxypropoxypropyl)methyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-(2,3-epoxypropoxypropyl)methyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethylmethyldimethoxysilane, 8-glycidyloxyoctyltrimethoxysilane, 1-(3-glycidyloxypropyl)-1,1,3,3,3-pentaethoxy-1,3-disilapropane, and combinations thereof.Exemplary mercapto-functional silanes may include, but are not limited to, 3-mercaptopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 11-mercaptoundecyltrimethoxysilane, S-(octanoyl)mercaptopropyltriethoxysilane, (mercaptomethyl)methyldiethoxysilane, 3-mercaptopropylmethyldimethoxysilane, mercaptopropyltrialkoxysilanes (e.g., mercaptopropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane), mercaptoundecyltrimethoxysilane, (mercaptomethyl)methyldiethoxysilane, and combinations thereof. In the example of a corrosion inhibitor coating composition, when two or more reactive silanes are included in the composition, it may be advantageous for the first reactive silane to be different from the second reactive silane. In this way, additional organic functionality can be imparted to the corrosion inhibitor coating composition, thereby increasing the potential reactive functional groups present in the corrosion inhibitor coating composition. Without being bound by any particular theory, the additional functional group chemistry within the corrosion inhibitor coating composition may provide versatility or utility for the corrosion inhibitor coating composition to be used in a variety of applications with respect to the polymer formulation layer, the substrate, or a combination thereof.

[0031]

[0038] The one or more silanes or organosilanes may be present in an amount of about 0.01 wt.% to about 15 wt.%, based on the total weight of the corrosion inhibitor coating composition. For example, the one or more organosilanes may be present in an amount of about 0.01 wt.%, about 0.5 wt.%, about 1 wt.%, about 1.5 wt.%, about 2 wt.%, or 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.%, based on the total weight of the corrosion inhibitor coating composition. In another example, the one or more organosilanes may be present in an amount of about 0.01 wt.% to about 10.0 wt.%, about 1 wt.% to about 8.0 wt.%, about 2.0 wt.% to about 6.0 wt.%, about 5 wt.%, or about 5 wt.%, based on the total weight of the corrosion inhibitor coating composition.

[0032]

[0039] The one or more organic solvents of the corrosion inhibitor coating composition may be capable of, or configured to, disperse, solubilize, solvate, or otherwise dissolve one or more substances or components of the corrosion inhibitor coating composition. The one or more organic solvents of the corrosion inhibitor coating composition may be capable of, or configured to, disperse, solubilize, solvate, or otherwise dissolve one or more substances, such as grease, oil, or debris, on a surface with which the corrosion inhibitor coating composition comes into contact. For example, the one or more organic solvents of the corrosion inhibitor coating composition may be capable of, or configured to, dissolve one or more of the components described for use in the corrosion inhibitor coating composition. The one or more organic solvents may also be capable of, or configured to, prepare a surface for subsequent processing or for the application of a sealant, coating, or other material that is applied 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 for the surface or substrate. It should be understood that any organic solvent capable of dissolving one or more components of the corrosion inhibitor coating composition and / or preparing the surface for subsequent processing or application of a coating material or adhesive can be utilized.

[0033]

[0040] The one or more organic solvents include, but are not limited to, aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, nitrated hydrocarbons, aromatic compounds such as ketones, amines, esters, alcohols, aldehydes, ethers, or combinations thereof.

[0034]

[0041] Exemplary aliphatic hydrocarbons that can be utilized as one or more organic solvents include, but are not limited to, n-pentane, n-hexane, n-octane, n-nonane, n-decane, or their homologs, 2,2,4-trimethylpentane, and the like, or any combination thereof.

[0035]

[0042] Exemplary aromatic compounds that can be utilized as the one or more organic solvents include, but are not limited to, cyclohexane, benzene, toluene, ethylbenzene, xylene, tetralin, hexafluoroxylene, and the like, or any combination thereof.

[0036]

[0043] Exemplary halogenated hydrocarbons that can be utilized as the one or more organic solvents include, but are not limited to, chloroform, trichloroethylene, dichloromethane, and the like, or any combination thereof.

[0037]

[0044] Exemplary ketone organic solvents include, but are not limited to, acetone, methyl ethyl ketone (MEK), diethyl ketone, methyl propyl ketone (MPK), dipropyl ketone, methyl isobutyl ketone (MIBK), cyclopentanone, cyclohexanone, methyl amyl ketone, n-methyl-2-pyrrolidone, diisobutyl ketone, acetophenone, and the like, or combinations thereof.

[0038]

[0045] Exemplary esters that can be utilized as the one or more organic solvents include, but are not limited to, methyl acetate, ethyl acetate, isopropyl acetate, n-butyl acetate, cellosolve acetate, and the like, or any combination thereof.

[0039]

[0046] Exemplary alcohols that can be utilized as the one or more organic solvents include, but are not limited to, methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, s-butanol, n-amyl alcohol, i-amyl alcohol, cyclohexanol, n-octanol, ethanediol, diethylene glycol, 1,2-propanediol, and the like, or any combination thereof.

[0040]

[0047] Exemplary aldehydes that can be utilized as the one or more organic solvents include, but are not limited to, furfuraldehyde, and the like.

[0041]

[0048] Exemplary ethers that can be used as the one or more organic solvents include, but are not limited to, diethyl ether, diisopropyl ether, dibutyl ether, methyl tertbutyl ether, 1,4-dioxane, tetrahydrofuran, oligomers of perfluoropolyethers (e.g., the Galden® product line available from Solvay, Houston, Texas), and the like, or combinations thereof.

[0042]

[0049] Certain embodiments of the corrosion inhibitor coating compositions described herein may have widely varying viscosities that can be adjusted depending on the application method. The amount of one or more organic solvents present in the corrosion inhibitor coating composition can vary widely, which can 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 methods such as brushing, airbrush spraying, spray gun, dripping, pouring, pipetting, wiping, and the like. The content of one or more organic solvents may be determined, at least in part, by the target or desired viscosity of the corrosion inhibitor coating composition. The content of one or more organic solvents in the corrosion inhibitor coating composition can be from about 75 wt % to about 99.5 wt %, based on the total weight of the corrosion inhibitor coating composition. For example, the amount of one or more organic solvents present in the corrosion inhibitor coating composition can be from about 75 wt%, about 80 wt%, about 85 wt%, or about 90 wt%, to about 95 wt%, about 98 wt%, about 99 wt%, or about 99.5 wt%, based on the total weight of the corrosion inhibitor coating composition. In another example, the amount of one or more organic solvents present in the corrosion inhibitor coating composition can be from about 75 wt% to about 99.5 wt%, about 80 wt% to about 99 wt%, about 85 wt% to about 95 wt%, or about 85 wt% to about 90 wt%, based on the total weight of the corrosion inhibitor coating composition. In another example, the viscosity or consistency of the sol-gel coating formulation can be adjusted by varying the ratio of the various organosilanes and the amount of solvent used in the formulation.

[0043]

[0050] The corrosion inhibitor coating composition may, for example, have a shear viscosity of about 0.01 Pa·s to about 10 Pa·s at a temperature of about 25°C. For example, the corrosion inhibitor coating composition may have a shear viscosity of 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 at a temperature of about 25°C. In another example, the corrosion inhibitor coating composition may have a shear viscosity of 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 at a temperature of about 25°C. Measurement of the corrosion inhibitor coating composition may be performed at a temperature of about 25°C and a shear rate of about 0.1 Hz to about 100 Hz. The corrosion inhibitor coating composition may have a shear viscosity of about 0.1 to about 100 sec -1 The composition may have a viscosity of about 0.01 to about 10 Pa·s at a shear rate of about 0.01 to about 10 Pa·s.

[0044]

[0051] The corrosion inhibitor coating composition may include one or more catalysts. As used herein, the term "catalyst" refers to any component, compound, or substance that can increase the rate of a chemical reaction associated with the cross-linking or formation of a coating, but does not necessarily undergo a permanent chemical change.

[0045]

[0052] The one or more catalysts may be present in an amount of about 0.1 wt.% to about 10 wt.%, based on the total weight of the corrosion inhibitor coating composition. For example, the one or more catalysts may be present in an amount of 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.%, about 6 wt.%, about 6.5 wt.%, about 7 wt.%, about 8 wt.%, about 9 wt.%, or about 10 wt.%, based on the total weight of the corrosion inhibitor coating composition. In another example, the one or more catalysts may be present in an amount of about 0.1 wt.% to about 5 wt.%, about 0.5 wt.% to about 2.5 wt.%, or about 0.5 wt.% to about 1.0 wt.%.

[0046] Example

[0053] Example 1: The corrosion-resistant (modified) conversion coating of Example 1 consists of two parts: Part A and Part B. Preparation of Part A involves adding glacial acetic acid (GAA, Sigma Aldrich) to zirconium propoxide (TPOZ, Sigma Aldrich) with stirring for 10 minutes. Ensure all glassware is completely dry at this point to avoid the formation of zirconium hydroxide. Deionized water was added to the GAA:TPOZ mixture and stirred for 10 minutes. The resulting solution remained translucent and was allowed to stand for two weeks to clarify. Preparation of Part B involved adding (3-glycidyloxypropyl)trimethoxysilane (GPTMS, Sigma Aldrich) to tetraethyl orthosilicate (TEOS, Sigma Aldrich) and stirring for 10 minutes. Ethanol (Hymann) was added to the GPTMS:TEOS mixture and stirred overnight (approximately 16 hours) to complete the hydrolysis and condensation reactions. 2,5-Dimercapto-1,3,4-thiadiazole (DMCT, Alfa Aesar) was added to the Part B mixture and stirred for 10 minutes. Finally, Part A was slowly added to Part B with vigorous stirring. TIFF2025186165000001.tif53170TIFF2025186165000002.tif68170

[0047]

[0054] The weight percentage of DMCT (2 wt. % with respect to the weight of the total corrosion-inhibiting composition) was calculated considering the weight percentages of both Part A and Part B. The pot life of the developed anti-corrosion coating was studied based on the sedimentation of DMCT particles.

[0048]

[0055] Coating Application: The developed anti-corrosion coating was spray applied to AA2024 panels with different aging time intervals of 5 minutes, 30 minutes and 2 hours.

[0049]

[0056] The coatings were cured at room temperature for 24 hours and then subjected to salt spray testing. Evaluation of 2,5-dimercapto-1,3,4-thiadiazole identified two color intensities between two different manufacturers, Acros Organics and Alfa Aesar. Confirmatory Fourier transform infrared (FTIR) analysis showed similar peaks for both compounds.

[0050]

[0057] The pot life of a corrosion-resistant Boegel coating using DMCT (Alfa Aesar) at different time intervals showed that the DMCT particles in Part B solution did not dissolve and were completely dispersed in the solution. No precipitation or settling was observed. The color of the solution changed to yellow. After adding Part A to the Part B solution, the color of the solution did not change. After 30 minutes, some particles began to settle to the bottom due to gravity. However, once mixed, the particles were uniformly dispersed in the stirred solution, and the color intensity was maintained. The pot life of a corrosion-resistant coating using DMCT (Acros Organics) was evaluated at different time intervals. The results also showed that the DMCT particles in Part B solution were completely dissolved. No precipitation or settling was observed. When Part A solution was added to Part B, the solution became translucent. After 10 minutes of stirring, the solution became clear. This prepared solution was used for application to AA 2024 panels.

[0051]

[0058] 2A-2C are photographs of exemplary coatings from Example 1 according to the present disclosure after coating treatment, after 168 hours of salt spray testing, and after 336 hours of salt spray testing, respectively. Evaluations of the various coatings shown in FIG. 2A are before salt spray testing and show that the corrosion-resistant coatings on the AA 2024 panels were clear and uniform. From left to right, the panels show photographic examples of Example 1 mixed and left for 5 minutes (two samples), 30 minutes (two samples), and 2 hours (two samples) intervals. The photograph shown in FIG. 2B shows the same six samples as in FIG. 2A after 168 hours of salt spray testing. No corrosion products were observed on the surfaces of the corrosion-resistant AA 2024 panels after 168 hours of salt spray exposure. The photograph shown in FIG. 2C shows the same six samples as in FIG. 2A after 336 hours of salt spray testing. No corrosion products were observed on the surface of the AA 2024 panels coated with the corrosion resistant coating after 336 hours of salt spray exposure.

[0052]

[0059] 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 separately to a reaction bottle and stirred using a magnetic stirrer for 10 minutes. Ethanol was added as a solvent and stirred for an additional 10 minutes. Distilled water was added over 10 minutes at room temperature with vigorous stirring. A 1N hydrochloric acid solution was added dropwise to ensure complete hydrolysis via an acid-catalyzed reaction. The final solution was stirred vigorously at room temperature (approximately 25°C) for 16 hours to ensure hydrolysis and condensation of the silica network. Finally, 1 wt% DMCT was added to the above sol-gel coating. The sol-gel solution was spray-applied at different intervals onto cleaned AA 2024 substrates and cured at room temperature. The cured coatings were analyzed using a salt spray test according to ASTM B117. TIFF2025186165000003.tif70170

[0053]

[0060] The pot life of TEOS, VTS sol-gel coatings using DMCT (Alfa Aesar) at different time intervals showed that the DMCT particles in the sol-gel solution did not dissolve but were completely dispersed. The solution color changed to yellow. No precipitation was observed. After 30 minutes, the DMCT particles began to settle to the bottom due to gravity. However, once mixed, the particles remained uniformly dispersed in the stirred solution, and the color intensity was maintained. The pot life of the sol-gel solution containing DMCT particles was determined by coating at three different time intervals: 5 minutes, 30 minutes, and 2 hours.

[0054]

[0061] Figures 3A-3C are photographs of exemplary coatings from Example 2 after coating treatment, 168 hours of salt spray testing, and 336 hours of salt spray testing, respectively, according to the present disclosure. Evaluations of the various coatings shown in Figure 3A are before salt spray testing, showing that the corrosion-resistant coatings on the AA 2024 panels were clear and uniform. From left to right, the panels show example photographs of Example 2 mixed and left for 5 minutes (two samples), 30 minutes (two samples), and 2 hours (two samples) of time. The TEOS, VTS, and DMCT sol-gel coatings on the AA 2024 panels were clear and uniform. Figure 3B shows the same six samples as Figure 3A after 168 hours of salt spray testing. No corrosion products were observed on the surfaces of the corrosion-resistant AA 2024 panels after 168 hours of salt spray exposure. Figure 3C shows the same six samples as Figure 3A after 336 hours of salt spray testing. No corrosion products were observed on the surface of the AA 2024 panels coated with the corrosion resistant coating after 336 hours of salt spray exposure.

[0055]

[0062] Example 3: Sol-gel coating formulation containing TEOS, MTMS, and DMCT (TEOS:MTMS (2:1)). A mixture of TEOS (2) and MTMS (1) was added separately to a reaction bottle and stirred with a magnetic stirrer for 10 minutes. 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. A 1N hydrochloric acid solution was added dropwise to ensure complete hydrolysis via an acid-catalyzed reaction. The final solution was stirred vigorously at room temperature for 16 hours to ensure hydrolysis and condensation of the silica network. Finally, 2 wt% DMCT was added to the above sol-gel coating to determine its pot life. The sol-gel solution was spray-applied at different intervals onto cleaned AA 2024 substrates and cured at room temperature. The cured coatings were analyzed using a salt spray test according to ASTM B117. TIFF2025186165000004.tif74170

[0056]

[0063] The pot life of TEOS,MTMS sol-gel coatings using DMCT at different time intervals showed that the DMCT particles in the sol-gel solution did not dissolve but were completely dispersed. The solution color changed to yellow. No precipitation was observed. After 30 minutes, the particles began to settle to the bottom due to gravity. However, once mixed, the stirring solution showed that the particles were uniformly dispersed and maintained their color intensity. The pot life of the sol-gel solution containing DMCT particles was determined by coating at three different time intervals: 5 minutes, 30 minutes, and 2 hours.

[0057]

[0064] Figures 4A-4C are photographs of exemplary coatings from Example 3 according to the present disclosure after coating treatment, after 168 hours of salt spray testing, and after 336 hours of salt spray testing, respectively. Evaluations of the various coatings shown in Figure 4A are from before the salt spray testing, demonstrating that the corrosion-resistant coatings on the AA 2024 panels were transparent and uniform. From left to right, the panels show example photographs of Example 3 mixed and left for 5 minutes (two samples), 30 minutes (two samples), and 2 hours (two samples) at intervals. Figure 4B shows the same six samples as Figure 4A after 168 hours of salt spray testing. No corrosion products were observed on the surfaces of the corrosion-resistant AA 2024 panels after 168 hours of salt spray exposure. Figure 2C shows the same six samples as Figure 4A after 336 hours of salt spray testing. No corrosion products were observed on the surface of the AA 2024 panels coated with the corrosion resistant coating after 336 hours of salt spray exposure.

[0058]

[0065] Example 4: Sol-gel coating formulation containing TEOS, GPTMS, and DMCT (TEOS:VTS (2:1)). A mixture of TEOS (2) and GPTMS (1) was added separately to a reaction bottle and stirred for 10 minutes using 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. A 1N hydrochloric acid solution was added dropwise to ensure complete hydrolysis via an acid-catalyzed reaction. The final solution was stirred vigorously at room temperature for 16 hours to ensure hydrolysis and condensation of the silica network. Finally, 2 wt% DMCT was added to the above sol-gel coating. The sol-gel solution was spray-applied at different intervals onto cleaned AA 2024 substrates and cured at room temperature. The cured coatings were analyzed using a salt spray test according to ASTM B117. TIFF2025186165000005.tif76170

[0059]

[0066] Pot-life evaluation of TEOS,GPTMS sol-gel coatings using DMCT at different time intervals showed that the DMCT particles in the sol-gel solution did not dissolve and were completely dispersed. The solution color changed to yellow. No precipitation was observed. After 30 minutes, the particles began to settle to the bottom due to the influence of gravity. Once mixed, the particles remained uniformly dispersed in the stirred solution, and the color intensity was maintained. The pot-life of the sol-gel solution containing DMCT particles was determined by coating at three different time intervals: 5 minutes, 30 minutes, and 2 hours.

[0060]

[0067] Figures 5A-5C are photographs of exemplary coatings from Example 4 according to the present disclosure after coating treatment, after 168 hours of salt spray testing, and after 336 hours of salt spray testing, respectively. Evaluations of the various coatings shown in Figure 5A are from before the salt spray testing, demonstrating that the corrosion-resistant coatings on the AA 2024 panels were transparent and uniform. From left to right, the panels show example photographs of Example 4 mixed and left for 5 minutes (two samples), 30 minutes (two samples), and 2 hours (two samples) at intervals. Figure 4B shows the same six samples as Figure 4A after 168 hours of salt spray testing. No corrosion products were observed on the surfaces of the corrosion-resistant AA 2024 panels after 168 hours of salt spray exposure. Figure 4C shows the same six samples as Figure 4A after 336 hours of salt spray testing. After 336 hours of salt spray exposure, slight corrosion products were observed at the edges of the AA2024 panel treated with TEOS and MTMS sol-gel coatings, but no corrosion was observed in the center.

[0061]

[0068] Generally, the steps involved in synthesizing the sol-gel coatings applied to the corrosion-inhibiting coating compositions described herein include the following steps.

[0062]

[0069] Hydrolysis: Various ethoxysilanes (in our example, methoxysilanes) are used in the sol-gel synthesis. In the hydrolysis step, all ethoxy / ethyl (or methoxy / methyl) groups are hydrolyzed in the presence of water to produce hydroxysilane molecules.

[0063]

[0070] Condensation: In the condensation step, the condensation of water, alcohols, or both occurs in the presence of a catalyst to produce crosslinked siloxanes in which silane molecules bond together to form Si-O-Si linkages / bonds.

[0064]

[0071] Polymerization: In the polymerization process, all the siloxane molecules react with each other to form a chain structure in the presence of heat or light (such as a photoinitiator (hv)). To polymerize, an organic group or polymerizable group is required.

[0065]

[0072] Other additives: As an example, 2,5-dimercapto-1,3,4-thiadiazole or other additives can be added to the sol-gel synthesis to either react with groups within the siloxane molecule or become suspended within the siloxane network, promoting corrosion resistance of the coating.

[0066]

[0073] While the present teachings have been illustrated with respect to one or more embodiments, changes and / or modifications can be made to the illustrated examples without departing from the spirit and scope of the appended claims. For example, even if the present process is described as a series of acts or events, it will be understood that the ordering of these acts or events is not intended to limit the present teachings. Some acts may occur in a different order and / or may occur concurrently with other actions or events than those described herein. Also, not all steps may be required to implement a method in accordance with one or more aspects or embodiments of the present teachings. It will be recognized that structures and / or process steps may be added, or existing structures and / or process steps may be removed or modified. Furthermore, one or more acts described herein may be performed as one or more separate acts and / or steps. Furthermore, the terms "including / includes," "having / has," "with," or subsequent variations thereof, where used in either the detailed description or the claims, are intended to be inclusive, similar in meaning to the word "comprising." The phrase "at least one of" is used to mean that one or more of the listed items may be selected. Furthermore, in the description and claims herein, the term "on" when used in connection with two materials, such as one "on" the other, means that there is at least some contact between the materials, whereas "over" means that the materials are in close proximity to one another, possibly with one or more additional intervening materials, and that contact is possible but not required. Neither "on" nor "over," as used herein, implies any directionality. The term "conformal" refers to a coating material in which corners of a substrate are protected by a conformal material. The term "about" indicates that the stated value may be varied somewhat without resulting in non-compliance of the process or structure with the illustrated embodiment.The terms "couple," "coupled," "connect," "connection," "connected," "in connection with," and "connecting" refer to "in direct connection with" or "in connection with through one or more intermediate elements or members." Finally, the term "exemplary" or "illustrative" indicates that the description is being used as an example, rather than to imply ideality. Other embodiments of the present teachings may be apparent to those skilled in the art based on the description herein and practice of the present disclosure. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

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

2. 10. The corrosion inhibitor coating composition (128) of claim 1, wherein the at least one reactive silane comprises tetraethoxysilane (TEOS).

3. 10. The corrosion inhibitor coating composition of claim 1, wherein the at least one reactive silane comprises vinyltriethoxysilane (VTS), 3-glycidyloxypropyltrimethoxysilane (GPTMS), methyltrimethoxysilane (MTMS), or a combination thereof.

4. 10. The corrosion inhibitor coating composition (128) of claim 1, which is chromium-free.

5. The corrosion inhibitor coating composition (128) of claim 1, wherein the catalyst comprises zirconium isopropoxide.

6. The corrosion inhibitor coating composition (128) of claim 1, wherein the catalyst comprises acetic acid.

7. 10. The corrosion inhibitor coating composition (128) of claim 1, wherein the 2,5-dimercapto-1,3,4-thiadiazole (DMCT) is present in an amount of from about 0.1% to about 5.0% by total weight of the corrosion inhibitor coating composition (128).

8. 10. The corrosion inhibitor coating composition (128) of claim 1, wherein the at least one reactive silane comprises a first reactive silane and a second reactive silane, and wherein a weight ratio of the first reactive silane to the second reactive silane is from about 0.5:1 to about 3:

1.

9. 10. The corrosion inhibitor coating composition (128) of claim 1, wherein the corrosion inhibitor further comprises a thiadiazole, a benzotriazole, an imidazole, or a combination thereof.

10. An article, Base material (130, 136); a corrosion inhibitor coating composition (128) disposed on a surface of the substrate (130, 136), comprising: 2,5-dimercapto-1,3,4-thiadiazole (DMCT); at least one reactive silane; and catalyst A corrosion inhibitor coating composition (128) comprising Including, The article, wherein the at least one reactive silane comprises tetraethoxysilane (TEOS), vinyltriethoxysilane (VTS), 3-glycidyloxypropyltrimethoxysilane (GPTMS), or a combination thereof.

11. The article of claim 10, wherein the corrosion inhibitor coating composition (128) is chromium-free.

12. 11. The article of claim 10, wherein the catalyst comprises zirconium isopropoxide, acetic acid, hydrochloric acid, or a combination thereof.

13. The article of claim 10, wherein the 2,5-dimercapto-1,3,4-thiadiazole (DMCT) is present in an amount of from about 0.1% to about 5.0% of the total weight of the corrosion inhibitor coating composition (128).

14. The article of claim 10, wherein the corrosion inhibitor coating composition (128) has a thickness of from about 30 nm to about 10 microns.

15. The article of claim 10, wherein the substrate (130, 136) comprises a metal, a polymer, a polymer composite, or a combination thereof.

16. The article of claim 10, wherein the substrate (130, 136) comprises nickel-plated steel.

17. The article of claim 10, wherein no adhesive or primer is present between the substrate (130, 136) and the corrosion inhibitor coating composition (128).

18. The article of claim 10, wherein the article is a component or part of an aerospace vehicle (100) or a marine vehicle (100).

19. A method for applying a corrosion inhibitor coating, comprising: forming a corrosion inhibitor coating composition (128) comprising 2,5-dimercapto-1,3,4-thiadiazole (DMCT), at least one reactive silane, a catalyst, and a solvent; applying the corrosion inhibitor coating composition (128) to a surface of a substrate (130, 136); exposing said corrosion inhibitor coating composition (128) to a curing temperature; A method comprising:

20. 20. A method for preparing the corrosion inhibitor coating composition (128) of claim 19, comprising: the corrosion inhibitor coating composition (128) has a thickness of from about 100 nm to about 10 microns; The method wherein the curing temperature is from about 15°C to about 150°C.

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