Corrosion-resistant adhesive sol-gel

Abstract

The present disclosure relates to a system and method for a coated substrate having a metal substrate and a sol-gel coating disposed on the metal substrate. The sol-gel includes a corrosion inhibitor and a reaction product of a surfactant and an epoxy-containing organosilane, a metal alkoxide, and an acid. The coated substrate includes an organic undercoat coating having an organic undercoat agent having a plurality of metal particles.

Description

Technical Field

[0001] Related Applications

[0001] This application claims the benefit and priority of U.S. Patent Application No. 63 / 339,276, filed on May 6, 2022, the content of which is incorporated herein by reference.

[0002] Field

[0002] Aspects of the present disclosure generally relate to corrosion-resistant sol-gel films for aerospace applications.

Background Art

[0003] Background

[0003] Metals such as steel, aluminum, aluminum alloys, and zinc-plated metals used in the manufacture of aircraft, spacecraft, and other machinery are prone to corrosion. Chromates such as zinc salts of hexavalent chromium have been used as corrosion inhibitors in corrosion-inhibiting coatings such as paints, sealants, and primers. However, chromates and other corrosion inhibitors often have poor adhesion to metal substrates. Furthermore, there is regulatory pressure to eliminate the use of hexavalent chromium and other chromates from conversion coatings, primers, and manufacturing processes.

[0004]

[0004] Generally, adhesive sol-gel films have been placed at the interface between a metal substrate and a corrosion inhibitor to promote adhesion. However, adhesive sol-gels do not themselves retain corrosion-resistant properties. Thus, over time, pores that trap water in the sol-gel form and promote corrosion of the metal surface. There is a desire to incorporate corrosion inhibitors that do not have other primers such as chromates and aluminum primers to increase the adhesion ability to the metal substrate or the primer placed on the sol-gel while maintaining the anticorrosion ability.

[0005]

[0005] Therefore, there is a need in the art for a sol-gel having a corrosion-inhibiting function that maintains proper adhesion to a metal substrate even when coated with a primer coating.

Summary of the Invention

[0006]

[0006] The present disclosure relates to a coated substrate having a metal substrate and a sol-gel coating disposed on the metal substrate. The sol-gel includes a corrosion inhibitor, a surfactant, and a reaction product of an epoxy-containing organosilane, a metal alkoxide, and an acid. The coated substrate includes an organic undercoat coating having a plurality of metal particles.

[0007]

[0007] The present disclosure also relates to a method for preparing a coated substrate. The method includes applying a sol-gel coating to a metal substrate to form a sol-gel coating, the sol-gel coating including a corrosion inhibitor. The method includes applying an undercoat coating to the sol-gel coating to form an undercoat coating, the undercoat coating including a metal.

[0008]

[0008] As the above features of the present disclosure are to be understood in detail, a more detailed description of the present disclosure, briefly summarized above, can be obtained by referring to the aspects, some of which are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings merely illustrate typical aspects of the present disclosure and should not be considered as limiting its scope, as the present disclosure may admit other equally effective aspects.

Brief Description of the Drawings

[0009]

Figure 1

[0009] A side view of a corrosion-inhibiting sol-gel disposed on a substrate according to an aspect of the present disclosure.

Figure 2

[0010] A schematic diagram of a method for preparing a coated substrate according to an aspect of the present disclosure.

Figure 3

[0011] An exemplary potentiodynamic scan of a metal surface of a corrosion-resistant sol-gel according to an aspect of the present disclosure is shown.

Figure 4

[0012] An exemplary OPR current graph of a corrosion-resistant sol-gel according to an aspect of the present disclosure.

Figure 5

[0013] An exemplary current-voltage graph of a corrosion-resistant sol-gel on the surface of an electrode according to an aspect of the present disclosure.

Figure 6

[0014] A and B show SEM images of a corrosion-resistant sol-gel according to an aspect of the present disclosure. A is an SEM image of a thin corrosion-resistant sol-gel. B is an SEM image of a thick corrosion-resistant sol-gel.

Figure 7

[0015] A graph of an exemplary corrosion-resistant sol-gel thickness of a corrosion-resistant sol-gel according to an aspect of the present disclosure.

Figure 8

[0016] A graph of an exemplary weight of a corrosion-resistant sol-gel coating of a corrosion-resistant sol-gel according to an aspect of the present disclosure.

Figure 9

[0017] An exemplary absorption spectrum of a corrosion-resistant sol-gel according to an aspect of the present disclosure is shown.

Figure 10

[0018] An exemplary current-voltage graph of a corrosion-resistant sol-gel according to an aspect of the present disclosure.

Figure 11

[0019] A corrosion-resistant sol-gel after being placed on bare 2024-T3 for 336 hours according to an aspect of the present disclosure is shown.

Figure 12

[0020] An exemplary impedance-generation frequency spectrum of a corrosion-resistant sol-gel according to an aspect of the present disclosure.

Figures 13A - 13C

[0021] A to C show a substrate coated with a corrosion-resistant sol-gel according to an embodiment of the present disclosure and a substrate coated in a comparative example after exposure to ASTM B117 for 2000 hours. A is the first substrate coated in the comparative example after exposure to ASTM B117 for 2000 hours. B is the first substrate coated with the first corrosion-resistant sol-gel after exposure to ASTM B117 for 2000 hours. C is the first substrate coated with the second corrosion-resistant sol-gel after exposure to ASTM B117 for 2000 hours.

Figures 13D - 13F

Figure 14

[0022] A to C show an exposed 7075-T6 panel coated with a corrosion-resistant sol-gel according to an embodiment of the present disclosure and a substrate coated in a comparative example after exposure outdoors for 9 months. A is the exposed 7075-T6 coated in the comparative example. B is the exposed 7075-T6 coated with the first corrosion-resistant sol-gel. C is the exposed 7075-T6 coated with the second corrosion-resistant sol-gel.

Figures 15A - 15C

[0023] A - C show exposed Al 7075 - T6 panels that have undergone corrosion - resistant sol - gel pretreatment with various primers according to aspects of the present disclosure after 2000 hours of exposure in an NSS chamber. A shows an exposed Al 7075 - T6 panel that has undergone pretreatment according to a comparative example using Av - de Al rich. B shows an exposed Al 7075 - T6 panel that has undergone pretreatment with a first corrosion - resistant sol - gel using Av - de Al rich. C shows an exposed Al 7075 - T6 panel that has undergone pretreatment with a second corrosion - resistant sol - gel using Av - de Al rich.

Figures 15D - 15F

[0023] D - F show exposed Al 7075 - T6 panels that have undergone corrosion - resistant sol - gel pretreatment with various primers according to aspects of the present disclosure after 2000 hours of exposure in an NSS chamber. D shows an exposed Al 7075 - T6 panel that has undergone pretreatment according to a comparative example using Akzo Nobel Aerodur 2118. E shows an exposed Al 7075 - T6 panel that has undergone pretreatment with a first corrosion - resistant sol - gel using Akzo Nobel Aerodur 2118. F shows an exposed Al 7075 - T6 panel that has undergone pretreatment with a second corrosion - resistant sol - gel using Akzo Nobel Aerodur 2118.

Figure 16

[0024] A - D show exposed 7075 - T6 panels that have undergone Alodine 1200S as a pretreatment, various primers, and a PPG 99GY001 polyurethane topcoat according to aspects of the present disclosure after 3000 hours of an ASTM B117 test. A shows an exposed 7075 - T6 panel that has undergone the PPG RW 7171 - 64 primer. B shows an exposed 7075 - T6 panel that has undergone the Av - dec Al rich primer. C shows an exposed 7075 - T6 panel that has undergone the Aerodur 2118 primer. D shows an exposed 7075 - T6 panel that has undergone the PPG CA7231 primer.

Figure 17

[0025] A - D show bare 7075 - T6 panels that have been subjected to Alodine 5900 as a pretreatment, various non - chromate primers, and PPG 99GY001 polyurethane topcoat according to aspects of the present disclosure after 3000 hours of ASTM B117 testing. A shows a bare 7075 - T6 panel with PPG RW 7171 - 64 primer. B shows a bare 7075 - T6 panel with Av - dec Al - rich primer. C shows a bare 7075 - T6 panel with Aerodur 2118 primer. D shows a bare 7075 - T6 panel with PPG CA7231 primer.

Figure 18

[0026] A - D show bare 7075 - T6 panels that have been subjected to SurTec 650V as a pretreatment, various non - chromate primers, and PPG 99GY001 polyurethane topcoat according to aspects of the present disclosure after 3000 hours of ASTM B117 testing. A shows a bare 7075 - T6 panel with PPG RW 7171 - 64 primer. B shows a bare 7075 - T6 panel with Av - dec Al - rich primer. C shows a bare 7075 - T6 panel with Aerodur 2118 primer. D shows a bare 7075 - T6 panel with PPG CA7231 primer.

Figure 19

[0027] A - D show bare 7075 - T6 panels with the corrosion - resistant sol - gel of the present disclosure that have been subjected to DMCT as a pretreatment, various non - chromate primers, and PPG 99GY001 polyurethane topcoat according to aspects of the present disclosure after 3000 hours of ASTM B117 testing. A shows a bare 7075 - T6 panel with PPG RW 7171 - 64 primer. B shows a bare 7075 - T6 panel with Av - dec Al - rich primer. C shows a bare 7075 - T6 panel with Aerodur 2118 primer. D shows a bare 7075 - T6 panel with PPG CA7231 primer.

Figure 20

[0028] A - D show 7178 panels that, after 3000 hours of ASTM B117 testing, were pretreated with Alodine 1200S, various non - chromate primers, and PPG 99GY001 polyurethane topcoat according to aspects of the present disclosure. A shows a bare 7178 panel treated with PPG RW 7171 - 64 primer. B shows a bare 7178 panel treated with Av - dec Al - rich primer. C shows a bare 7178 panel treated with Aerodur 2118 primer. D shows a bare 7178 panel treated with PPG CA7231 primer.

Figure 21

[0029] A - D show 7178 panels that, after 3000 hours of ASTM B117 testing, were pretreated with Alodine 5900, various non - chromate primers, and PPG 99GY001 polyurethane topcoat according to aspects of the present disclosure. A shows a bare 7178 panel treated with PPG RW 7171 - 64 primer. B shows a bare 7178 panel treated with Av - dec Al - rich primer. C shows a bare 7178 panel treated with Aerodur 2118 primer.

Figure 22

[0030] A - D show 7178 panels that, after 3000 hours of ASTM B117 testing, were pretreated with SurTec 650V, various non - chromate primers, and PPG 99GY001 polyurethane topcoat according to aspects of the present disclosure. A shows a bare 7178 panel treated with PPG RW 7171 - 64 primer. B shows a bare 7178 panel treated with Av - dec Al - rich primer. C shows a bare 7178 panel treated with Aerodur 2118 primer.

Figure 23

[0031] A and B show exposed 7178 panels having the corrosion-resistant sol-gel of the present disclosure with DMCT as a pretreatment, various non-chromate primers, and PPG 99GY001 polyurethane topcoat according to an aspect of the present disclosure after 3000 hours of ASTM B117 test. A shows an exposed 7178 panel with PPG RW 7171-64 primer. B shows an exposed 7178 panel with Av-dec Al-rich primer.

Figure 24

[0032] It is an exemplary graph comparing rankings using multiple methods for 7075-T6 test panels that have completed 3000 hours of exposure to an NSS chamber according to an aspect of the present disclosure.

Figure 25

[0033] It is an exemplary graph comparing rankings using multiple methods for 7178 test panels that have completed 2000 hours of exposure to an NSS chamber according to an aspect of the present disclosure.

Figure 26

[0034] It is an exemplary graph comparing rankings for 7075-T6 test panels that have completed 3000 hours of exposure to an NSS chamber and 672 hours of exposure to a cyclic acceleration chamber according to an aspect of the present invention.

Figure 27

[0035] It is an exemplary graph comparing rankings for 7178 test panels that have completed 3000 hours of exposure to an NSS chamber and 672 hours of exposure to a cyclic acceleration chamber according to an aspect of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0010]

[0036] Aspects of the present disclosure generally relate to corrosion-resistant sol-gels for aerospace applications. The sol-gel of the present disclosure comprises an epoxy-containing organosilane, a metal alkoxide, an acid stabilizer, a corrosion inhibitor in an amount of about 3 wt% to about 15 wt% based on the total volume of the sol-gel coating, and a surfactant (or reaction product thereof). It has been discovered that the surfactant present in the sol-gel suppresses or reduces the absorption of water within the sol-gel, thereby suppressing or reducing the pores and water blistering of the sol-gel / undercoat coating on the metal surface, resulting in a corrosion inhibition ability of the sol-gel film. The surfactant also enables an increase in the hydration of the coating on the surface of the metal, improving the adhesion and corrosion performance of the coating. Additionally, it has been found that the use of an organic undercoat disposed on a corrosion-resistant sol-gel having a plurality of metal particles, such as aluminum or lithium, enhances the corrosion protection of alloys (e.g., aerospace alloys). The sol-gel of the present disclosure has a corrosion inhibition ability, and the undercoat (disposed on the sol-gel) can be non-chromium-containing or chromium-containing.

[0011]

[0037] A method for preparing a coated substrate of the present disclosure includes applying a sol-gel coating to a metal substrate to form a sol-gel coating. The sol-gel coating contains a corrosion inhibitor in an amount of about 3 wt% to about 15 wt% based on the weight of the sol-gel coating.

[0012] Metal substrate

[0038] The metal substrate includes a metallic aircraft surface, which can include an alloy having a main component such as steel or aluminum. The metal substrate can include a main component and a secondary component known as an intermetallic compound. The intermetallic compound can contain, for example, a copper metal that is prone to corrosion. The metal substrate can include an aluminum substrate. The metal substrate can include an aluminum substrate containing a copper intermetallic compound. As a non-limiting example, the metal substrate can be a 7075-T6 aluminum substrate or a 7178 aluminum substrate.

[0013] Sol-gel

[0039] The term "sol-gel", i.e., the shrinkage-gelation of a solution, refers to a series of reactions in which soluble metal species (typically metal alkoxides or metal salts) are hydrolyzed to form metal hydroxides. The soluble metal species usually contain organic ligands adjusted to correspond to the resin in the bonding structure. The soluble metal species undergo hetero-hydrolysis and hetero-metal bonding, such as heterocondensation to form Si-O-Zr. In the absence of an organic acid, when a metal alkoxide is added to water, for example, a white precipitate of Zr(OH) 2 is rapidly formed. Zr(OH) 2 is insoluble in water and hinders sol-gel formation. By adding an acid to the metal alkoxide, an aqueous system becomes possible. Depending on the reaction conditions, the metal polymer can condense into colloidal particles or grow to form a network gel. To maximize the performance for a specific application, the ratio of organic to inorganic matter in the polymer matrix is controlled.

[0014]

[0040] The sol-gel has a thickness of from about 50 nm to about 4 μm, for example, from about 100 nm to about 2.5 μm, for example, about 100 nm, about 200 nm, about 300 nm, about 400 nm, about 500 nm, about 600 nm, about 700 nm, about 800 nm, about 900 nm, about 1 μm, about 2 μm, or about 2.5 μm, etc. The sol-gel has a density of from about 30 mg / ft 2 to about 1,000 mg / ft 2 , for example, from about 30 mg / ft 2 to about 400 mg / ft 2 , or from about 250 mg / ft 2 to about 1000 mg / ft 2 , for example, about 30 mg / ft 2 , about 100 mg / ft 2 , about 200 mg / ft 2 , about 300 mg / ft 2 , about 400 mg / ft 2 , about 500 mg / ft 2 , about 600 mg / ft 2 , about 700 mg / ft 2 , about 800 mg / ft2 , having a weight of about 900 mg / ft 2 , or about 1000 mg / ft 2 and so on.

[0015] Organosilane

[0041] The weight fraction (wt%) of the organosilane in the sol-gel is from about 0.1 wt% to about 20 wt%, for example from about 0.3 wt% to about 15 wt%, for example from about 0.5 wt% to about 10 wt%, for example from about 0.7 wt% to about 5 wt%, for example from about 1 wt% to about 2 wt%, for example about 1 wt%, about 1.5 wt%, about 2 wt% with respect to the volume of the entire sol-gel coating.

[0016]

[0042] The organosilane of the present disclosure has the formula (I): represented by TIFF2025516507000002.tif29170, wherein in the above formula, R 2 , R 3 and R 4 each independently is a linear or branched C 1-20 alkyl. C 1-20 alkyl includes methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and icosanyl. R 1 is selected from alkyl, cycloalkyl, ether, and aryl. Alkyl includes linear or branched C 1-20 alkyl. C 1-20 alkyl includes methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and icosanyl. Ether includes polyethylene glycol ether, polypropylene glycol ether, C 1 -C 20 alkyl ether, aryl ether, and cycloalkyl ether.

[0017]

[0043] The ether is selected from TIFF2025516507000003.tif169170, and in the above formula, n is a positive integer. In at least one embodiment, n is a positive integer, and the number average molecular weight (Mn) of the ether is from about 300 to about 500, such as from about 375 to about 450, such as from about 400 to about 425.

[0018]

[0044] The organosilane is a hydroxyorganosilane. The hydroxyorganosilane is substantially non-reactive with nucleophiles, such as some corrosion inhibitors. The hydroxyorganosilane of the present disclosure has the formula (II): represented by TIFF2025516507000004.tif27170, wherein in the above formula, R is selected from alkyl, cycloalkyl, ether, and aryl. The alkyl is linear or branched C 1-20 alkyl-containing. C 1-20 alkyl includes methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, and icosanyl. The ether includes polyethylene glycol ether, polypropylene glycol ether, C 1 -C 20 alkyl ether, aryl ether, and cycloalkyl ether.

[0019]

[0045] The ether is selected from TIFF2025516507000005.tif169170, and in the above formula, n is a positive integer. In at least one embodiment, n is a positive integer, and the number average molecular weight (Mn) of the ether is from about 300 to about 500, such as from about 375 to about 450, such as from about 400 to about 425.

[0020]

[0046] The organosilane is Compound 1 or Compound 2: It is represented by TIFF2025516507000006.tif87170.

[0021]

[0047] The organosilane is selected from 3-aminopropyltriethoxysilane, 3-glycidoxypropyltriethoxysilane, p-aminophenyltrimethoxysilane, p-aminophenyltriethoxysilane, allyltrimethoxysilane, allyltriethoxysilane, n-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropyl diisopropyl ethoxysilane, (3-glycidoxypropyl)methyldiethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-methacryloxypropylmethyldiethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, n-phenylaminopropyltrimethoxysilane, vinylmethyldiethoxysilane, vinyltriethoxysilane, vinyltrimethoxysilane, bis(trimethoxysilyl)ethane, bis(triethoxysilyl)ethane, bis[3-(trimethoxysilyl)propyl]amine, bis[3-(triethoxysilyl)propyl]amine, bis[3-(triethoxysilyl)propyl]disulfide, bis[3-(trimethoxysilyl)propyl]disulfide, bis[3-(triethoxysilyl)propyl]trisulfide, bis[3-(trimethoxysilyl)propyl]trisulfide, bis[3-(triethoxysilyl)propyl]tetrasulfide, and bis[3-(trimethoxysilyl)propyl]tetrasulfide.

[0022]

[0048] The organosilanes useful for forming the sol-gel of the present disclosure provide an electrophilic silicon and / or epoxide moiety that can react with a nucleophile such as, for example, a hydroxy-containing nucleophile. The organosilanes of the present disclosure provide a sol-gel having a reduced porosity and swelling compared to conventional sol-gels.

[0023] Metal alkoxide

[0049] The metal alkoxides useful for forming the sol-gel of the present disclosure provide metal atoms coordinated within the sol-gel for adhesive and mechanical strength. The metal alkoxides of the present disclosure include at least one of zirconium alkoxide, titanium alkoxide, hafnium alkoxide, yttrium alkoxide, cerium alkoxide, and lanthanum alkoxide. The metal alkoxide can have four alkoxy ligands coordinated to a metal having an oxidation number of +4. Non-limiting examples of metal alkoxides are zirconium(IV) tetramethoxide, zirconium(IV) tetraethoxide, zirconium(IV) tetra-n-propoxide, zirconium(IV) tetra-isopropoxide, zirconium(IV) tetra-n-butoxide, zirconium(IV) tetra-isobutoxide, zirconium(IV) tetra-n-pentoxide, zirconium(IV) tetra-isopentoxide, zirconium(IV) tetra-n-hexoxide, zirconium(IV) tetra-ishexoxide, zirconium(IV) tetra-n-heptoxide, zirconium(IV) tetra-isheptoxide, zirconium(IV) tetra-n-octoxide, zirconium(IV) tetra-n-isooctoxide, zirconium(IV) tetra-n-nonoxide, zirconium(IV) tetra-n-isononoxide, zirconium(IV) tetra-n-decyloxide, and zirconium(IV) tetra-n-isodecyloxide.

[0024]

[0050] The sol-gel contains a metal alkoxide content, and the metal alkoxide content is the reaction product of the metal alkoxide formed in the sol-gel. The weight fraction (wt%) of the metal alkoxide content with respect to the total volume of the sol-gel coating is from about 0.1 wt% to about 10 wt%, for example from about 0.2 wt% to about 5 wt%, for example from about 0.3 wt% to about 3 wt%, for example from about 0.4 wt% to about 2 wt%, for example from about 0.5 wt% to about 1 wt%, for example about 0.2 wt%, about 0.5 wt%, about 1 wt%.

[0025] Acid stabilizer

[0051] The acid stabilizer used to form the sol-gel of the present disclosure provides stabilization of the metal alkoxide and corrosion inhibitor of the sol-gel, as well as a decrease in the pH of the sol-gel. The pH value of the sol-gel (and the composition forming the sol-gel) can be controlled by the use of an acid stabilizer. The acid stabilizer of the present disclosure contains an organic acid. The organic acid includes acetic acid (e.g., glacial acetic acid) or citric acid. Acids with relatively low acidity (e.g., pKa greater than acetic acid) such as glycol, ethoxyethanol or H 2 NCH 2 CH 2 OH can also be used as the acid stabilizer.

[0026]

[0052] The pH of the sol-gel of the present disclosure is from about 2 to about 5, for example from about 3 to about 4. The weight fraction (wt%) of the acid stabilizer with respect to the total volume of the sol-gel is from about 0.1 wt% to about 10 wt%, for example from about 0.2 wt% to about 5 wt%, for example from about 0.3 wt% to about 3 wt%, for example from about 0.4 wt% to about 2 wt%, for example from about 0.5 wt% to about 1 wt%, for example about 0.1 wt%, about 0.2 wt%, about 0.3 wt%, about 0.4 wt%, about 0.5 wt%. For example, but not limited to, the wt% of the acid stabilizer in the sol-gel is about 0.5 wt%, and the weight fraction of the metal alkoxide is about 0.6 wt% or more. As a further non-limiting example, the wt% of the acid stabilizer in the sol-gel is about 0.3 wt%, and the weight fraction of the metal alkoxide is less than 0.6 wt%.

[0027]

[0053] The ratio of the metal alkoxide to the acid stabilizer in the sol-gel can be from about 1:1 to about 3:1, for example about 2:1. The molar ratio of the acid stabilizer to the metal alkoxide can be from about 1:1 to about 40:1, for example from about 3:1 to about 8:1, for example from about 4:1 to about 6:1, for example from about 4:1 to about 5:1.

[0028]

[0054] Without being bound by theory, these ratios of acid stabilizer not only contribute to the stabilization of the metal alkoxide against hydrolysis, but also protonate the thiol moiety of the corrosion inhibitor, thereby reducing or preventing the reaction of the corrosion inhibitor, for example, with the metal alkoxide.

[0029]

[0055] Surfactant

[0056] Without being bound by theory, the surfactant useful for forming the sol-gel of the present disclosure enhances the adhesion of the sol-gel to the metal substrate by increasing the surface wettability of the coating to the surface of the metal. The surfactant can enhance the adhesion and can be quantified according to the wet cross-hatch adhesion according to ASTM D3359. For example, without limitation, the sol-gel having a surfactant can increase the wet cross-hatch adhesion to a value of 10.

[0030]

[0057] Without being bound by theory, the surfactant useful for forming the sol-gel of the present disclosure enhances the adhesion of the sol-gel to the primer. The surfactant of the present disclosure can include a surfactant capable of carrying out an alkoxylation reaction in which the addition of an epoxide to the substrate occurs. The surfactant can include one or more alcohol ethoxylates, alcohol propoxylates, ethoxysulfates, or polyethoxylated amines, etc. For example, without limitation, the surfactant can be ethylene-oxide alcohol, propylene-oxide alcohol, ethylene-oxide-propylene-oxide alcohol, polyethoxylated tallow amine, ethanolamine, diethanolamine, or triethanolamine, etc.

[0031] Corrosion inhibitor

[0058] The corrosion inhibitors useful for forming the sol-gel of the present disclosure provide corrosion resistance (to water) of a metal substrate disposed adjacent to the sol-gel. The corrosion inhibitors of the present disclosure are compounds having one or more thiol moieties. The surface of a metal aircraft can comprise a steel or alloy having a main component such as aluminum and a minor component known as an intermetallic compound. For example, the intermetallic compound often contains copper metal which is prone to corrosion. Without being bound by theory, it is believed that the interaction between the thiol moiety of the corrosion inhibitor of the present disclosure and the copper-containing intermetallic compound on the metal surface (such as an aluminum alloy surface) suppresses the corrosion of the metal surface. Specifically, the interaction between the thiol moiety of the corrosion inhibitor of the present disclosure and the intermetallic compound blocks the reduction of the intermetallic compound by reducing the oxygen reduction rate and decreasing the oxidation of metal alloys such as aluminum alloys.

[0032]

[0059] The corrosion inhibitor of the present invention is an organic compound containing a disulfide group and / or a thiolate group (e.g., a metal-sulfide bond). For example, the corrosion inhibitor is not an organometallic corrosion inhibitor. The corrosion inhibitor has the formula: R 1 --S n --X--R 2 (wherein R 1 is an organic group, n is an integer of 1 or more, X is a sulfur or metal atom, and R 2 is an organic group). One or both of R 1 and R 2 can contain additional polysulfide groups and / or thiol groups. Further, the corrosion inhibitor contains a polymer having the formula -(R 1 --S n --X--R 2 ) q -(wherein R 1 is an organic group, n is a positive integer, X is a sulfur or metal atom, R 2 is an organic group, and q is a positive integer). R 1 and R 2(The (polymeric or monomeric corrosion inhibitor) is independently selected from H, alkyl, cycloalkyl, aryl, thiol, polysulfide or thione. R 1 and R 2 each can be independently substituted with a moiety selected from alkyl, amino, phosphorus-containing, ether, alkoxy, hydroxy, sulfur-containing, selenium or tellurium. R 1 and R 2 each has 1 to 24 carbon atoms and / or non-hydrogen atoms. For example, R 1 and R 2 Examples of heterocycles of the groups include azole, triazole, thiazole, dithiazole and / or thiadiazole.

[0033]

[0060] The corrosion inhibitor contains a metal in the metal-thiolate complex. The corrosion inhibitor can include a metal center and one or more thiol groups (ligands) bonded and / or coordinated to the metal center having a metal-sulfide bond. A thiolate is a derivative of a thiol in which a hydrogen to which a metal atom is bonded is replaced by sulfur. A thiolate has the general formula M-S--R 1 (wherein M is a metal and R 1 is an organic group). R 1 can contain a disulfide group. The metal-thiolate complex has the general formula M-(S--R 1 ) n (wherein n is generally an integer from 2 to 9 and M is a metal atom). The metal is copper, zinc, zirconium, aluminum, iron, cadmium, lead, mercury, silver, platinum, palladium, gold, and / or cobalt.

[0034]

[0061] The corrosion inhibitor contains an azole compound. Examples of suitable azole compounds include those with one nitrogen atom such as pyrrole, and those with two or more nitrogen atoms such as pyrazole, imidazole, triazole, tetrazole and pentazole, those with one nitrogen atom and one oxygen atom such as oxazole and isoxazole, and cyclic compounds with one nitrogen atom and one sulfur atom such as thiazole and isothiazole. Non-limiting examples of suitable azole compounds include 2,5-dimercapto-1,3,4-thiadiazole, 1H-benzotriazole, 1H-1,2,3-triazole, 2-amino-5-mercapto-1,3,4-thiadiazole (also known as 5-amino-1,3,4-thiadiazole-2-thiol), and 2-amino-1,3,4-thiadiazole. For example, but not limited to, the azole can be 2,5-dimercapto-1,3,4-thiadiazole. The azole can be present in the composition at a concentration from 0.01 g / L to 1 g / L of the sol-gel composition, such as 0.4 g / L of the sol-gel composition. The azole compound can include benzotriazole and / or 2,5-dimercapto-1,3,4-thiadiazole.

[0035]

[0062] The corrosion inhibitor of the present disclosure contains a heterocyclic thiol and an amine that can provide elimination of oxygen reduction. The heterocyclic thiol includes a thiadiazole having one or more thiol moieties. Non-limiting examples of thiadiazoles having one or more thiol moieties are of formula (III) or formula (IV): TIFF2025516507000007.tif29170 includes 1,3,4-thiadiazole-2,5-dithiol and thiadiazole represented thereby.

[0036]

[0063] The thiadiazole of formula (III) can be purchased from Vanderbilt Chemicals, LLC (Norwalk, Connecticut) and is known as Vanlube® 829. The thiadiazole of formula (IV) is from WPC Technologies, Inc. (Oak Creek, Wisconsin) TMcan be purchased from, InhibiCor TM is known as 1000.

[0037]

[0064] The corrosion inhibitor of the present disclosure is HS-CN for use as a corrosion inhibitor related to paints 2 derivatives of 2,5-dimercapto-1,3,4-thiadiazole and selected derivatives of trithiocyanuric acid ("TMT") represented by the symbol SC-SH or "DMTD". Examples include 2,5-dimercapto-1,3,4-thiadiazole (DMTD) and 2,4-dimercapto-s-triazolo-[4,3-b]-1,3-4-thiadiazole, as well as trithiocyanuric acid (TMT). Other examples include N-, S- and N,N-, S,S- and N,S-substituted derivatives of DMTD, such as 5-mercapto-3-phenyl-1,3,4-thiadiazolin-2-thione or bismuthiol II (3-phenyl-1,3,4-thiadiazolidine-2,5-dithione), as well as various S-substituted derivatives of trithiocyanuric acid. Other examples include 5,5’ dithio-bis(1,3,4-thiadiazole-2(3H)-thione or (DMTD) 2 or a polymer of DMTD (DMTD); 5,5’ thio-bis(1,3,4-thiadiazole-2(3H)-thione; or a dimer and polymer of TMT (TMT) 2 is included. Other examples include the general formula: M(DMTD) n (where n = 1, 2 or 3 and M is a metal cation, such as M = Zn(II), Bi(III), Co(II), Ni(II), Cd(II), Pb(II), Ag(I), Sb(III), Sn(II), Fe(II), or Cu(II) (e.g., ZnDMTD, Zn(DMTD) 2 , Bi(DMTD) 3 ) salts of DMTD); similar salts of TMT, such as ZnTMT in a 1:1 ratio; and also equivalent soluble Li(I), Ca(II), Sr(II), Mg(II), La(III), Ce(III), Pr(III), or Zr(IV) salts. Additional examples include the general formula M[(DMTD) n m ​(wherein n = 2 or n>2, m = 1, 2 or 3, and M is a metal cation, for example, M = Zn(II), Bi(III), Co(II), Ni(II), Cd(II), Pb(II), Ag(I), Sb(III), Sn(II), Fe(II) or Cu(II)). Typical examples are: Zn[(DMTD) 2 , Zn[(DMTD) 2 2 .

[0038]

[0065] Additional examples include ammonium-, aryl- or alkyl-ammonium salts of DMTD, (DMTD) n , or 5,5'-thio-bis(1,3,4-thiadiazole-2(3H)-thione or 2,4-dimercapto-s-triazolo-[4,3-b]-1,3,4-thiadiazole. Typical examples include cyclohexylamine:DMTD in ratios of 1:1 and 2:1, dicyclohexylamine:DMTD in ratios of 1:1 and 2:1, aniline:DMTD in ratios of 1:1 and 2:1, salts of TMT:TMT in a ratio of 1:1, such as similar to dicyclohexylamine. Further examples include polyammonium salts of DMTD or (DMTD) n and TMT formed with polyamines.

[0039]

[0066] Further examples include essentially conductive polyaniline doped with DMTD or (DMTD) 2 or 5,5'-thio-bis(1,3,4-thiadiazole-2(3H)-thione and TMT; essentially conductive polypyrrole and / or polythiophene doped with DMTD, (DMTD) 2 and 5,5'-thio-bis(1,3,4-thiadiazole-2(3H)-thione and / or TMT are included.

[0040]

[0067] ​Further examples include micro or nano composites of poly DMTD / polyaniline, poly DMTD / polypyrrole and poly DMTD / polythiophene; similar micro or nano composites with TMT; and those with 5,5’-thio-bis(1,3,4-thiadiazole-2(3H)-thione; DMTD or salts of DMTD or derivatives of DMTD and TMT as organic components of various pigment grade inorganic matrices or physical mixtures. Such inorganic matrices include non-toxic anion and cation species having corrosion inhibitor properties, such as: MoO 4 - , PO 4 - , HPO 3 - , poly-phosphate, BO 2 - , SiO 4 - , NCN - , WO 4 - , phosphomolybdates, phosphotungstates and may respectively contain Mg, Ca, Sr, La, Ce, Zn, Fe, Al, Bi.

[0041]

[0068] Further examples include encapsulated forms, for example as inclusion compounds or cyclodextrin clathrates within various polymer matrices, or microencapsulated forms, of DMTD or salts of DMTD or derivatives of DMTD and TMT.

[0042]

[0069] DMTD in pigment grade form is Zn(DMTD) using inorganic products or corrosion inhibitor pigments 2 and Zn-DMTD (among other organic and inorganic salts of the former), such as: phosphates, molybdates, borates, silicates, tungstates, phosphotungstates, phosphomolybdates, cyanamides or carbonates of the aforementioned cation species, and oxides. Examples include zinc phosphate, cerium molybdate, calcium silicate, strontium borate, zinc cyanamide, cerium phosphotungstate, ZnO, CeO 2 , ZrO 2 , and amorphous SiO 2 are included.

[0043]

[0070] The corrosion inhibitor is a counter ion that can include lithium ions and various ions known to form salts with lithium. Non-limiting examples of counter ions suitable for forming salts with lithium include carbonates, hydroxides, and silicates (such as orthosilicates and metasilicates). For example, the corrosion inhibitor includes lithium carbonate salts, lithium hydroxide salts, or lithium silicate salts (such as lithium orthosilicate salts or lithium metasilicate salts). The counter ion includes various ions known to form salts with other Group IA (or Group 1) metals (such as Na, K, Rb, Cs, and / or Fr). Non-limiting examples of counter ions suitable for forming salts with alkali metals include carbonates, hydroxides, and silicates (such as orthosilicates and metasilicates). For example, without limitation, the corrosion inhibitor includes alkali metal carbonates, alkali metal hydroxide salts, and / or alkali metal silicates (such as alkali metal orthosilicates or alkali metal metasilicates). For example, some non-limiting examples of suitable salts include carbonates, hydroxides, and silicates (such as orthosilicates or metasilicates) of sodium, potassium, rubidium, cesium, and francium.

[0044]

[0071] The corrosion inhibitor of the present disclosure includes compounds rich in aluminum and magnesium that can provide cathodic corrosion protection for materials. Corrosion inhibitors rich in aluminum include aluminum or aluminum alloys in an amount exceeding 50 wt% of the volume of the corrosion inhibitor. Corrosion inhibitors rich in magnesium include magnesium or magnesium alloys in an amount exceeding 50 wt% of the volume of the corrosion inhibitor. The corrosion inhibitor of the present disclosure may include cesium compounds.

[0045]

[0072] The weight fraction (wt%) of the corrosion inhibitor with respect to the total volume of the sol-gel is from about 1 wt% to about 15 wt%, such as from about 3 wt% to about 15 wt%, such as from about 1 wt% to about 5 wt%, such as from about 5 wt% to about 10 wt%, such as from about 10 wt% to about 15 wt%, such as from about 12 wt% to about 15 wt%, such as about 1 wt%, about 5 wt%, about 7 wt%, about 10 wt%, about 15 wt%. For example, but not limited to, the wt% of the corrosion inhibitor with respect to the total volume of the sol-gel is from about 3 wt% to about 15 wt%, and the weight fraction of the metal alkoxide is 0.6 wt% or more with respect to the total volume of the sol-gel. As a further non-limiting example, the wt% of the acid stabilizer with respect to the total volume of the sol-gel is from about 3 wt% to about 15 wt%, and the weight fraction of the metal alkoxide in the sol-gel is less than 0.6 wt% with respect to the total volume of the sol-gel. The corrosion inhibitor incorporated in the sol-gel provides an additional layer of corrosion protection adjacent to the metal surface. In addition, when used in the lamination of the non-chromate primer coating, this will promote corrosion protection.

[0046] Primer

[0073] The primer of the present disclosure can be disposed on the sol-gel coating to enhance the bonding adhesiveness of the aluminum surface and the subsequent adhesiveness to the epoxy primer. The primer of the present disclosure can be composed of a reactive polymer. For example, the primer can be composed of an epoxy, such as an amine-cured epoxy. The primer of the present disclosure can be composed of a siloxane, such as a polysiloxane. The primer of the present disclosure can contain from about 0 to about 30 wt% of the corrosion inhibitor by volume in the primer solution.

[0047]

[0074] The primer of the present disclosure includes an organic primer having a plurality of metal particles capable of preventing corrosion and filiform corrosion caused by a fastener. The metal particles can be sacrificially corroded to suppress the corrosion of the surface metal by oxidizing prior to the surface metal. The metal particles can include aluminum ions and counterions that can include various ions known to form salts with aluminum. Non-limiting examples of counterions suitable for forming salts with aluminum include carbonates, hydroxides, and silicates (e.g., orthosilicates and metasilicates). For example, without limitation, the counterions can include aluminum carbonate salts, aluminum hydroxide salts, or aluminum silicate salts (e.g., aluminum orthosilicate salts or aluminum metasilicate salts). The counterions can include various ions known to form salts with other Group 13 metals (e.g., B, Ga, In, Tl, Ho, and / or Es). Non-limiting examples of counterions suitable for forming salts with alkali metals include carbonates, hydroxides, and silicates (e.g., orthosilicates and metasilicates).

[0048]

[0075] The metal particles can include magnesium ions and counterions that can include various ions known to form salts with magnesium. Non-limiting examples of counterions suitable for forming salts with magnesium include carbonates, hydroxides, and silicates (e.g., orthosilicates and metasilicates). For example, without limitation, the corrosion inhibitor can include magnesium carbonate salts, magnesium hydroxide salts, or magnesium silicate salts (e.g., magnesium orthosilicate salts or magnesium metasilicate salts). The counterions can include various ions known to form salts with other Group 2 metals (e.g., Be, Ca, Sr, Ba, and / or Ra). Non-limiting examples of counterions suitable for forming salts with alkali metals include carbonates, hydroxides, and silicates (e.g., orthosilicates and metasilicates).

[0049]

[0076] The metal particles can include counterions that can include lithium ions and various ions known to form salts with lithium. Non-limiting examples of counterions suitable for forming salts with lithium include carbonates, hydroxides, and silicates (such as orthosilicates and metasilicates). For example, without limitation, the corrosion inhibitor can include lithium carbonate salts, lithium hydroxide salts, or lithium silicate salts (such as lithium orthosilicate salts or lithium metasilicate salts). The counterions can include various ions known to form salts with other Group IA (or Group 1) metals (such as Na, K, Rb, Cs, and / or Fr). Non-limiting examples of counterions suitable for forming salts with alkali metals include carbonates, hydroxides, and silicates (such as orthosilicates and metasilicates).

[0050]

[0077] The primer coating (disposed on the sol-gel) has a thickness of from about 0.3 mils to about 2.5 mils, such as from about 1.0 mil to about 2.0 mils, such as about 0.3 mil, about 0.5 mil, about 1.0 mil, about 1.5 mil, about 2.0 mil, or about 2.5 mil, etc.

[0051] Topcoat

[0078] The topcoat of the present disclosure can be disposed on the primer coating to form the sol-gel of the present disclosure that has corrosion resistance (to water) of a metal substrate disposed adjacent to the sol-gel. The topcoat can include an organic topcoat such as a polymer coating (e.g., an epoxy coating and / or a urethane coating), a polymer material, a composite material (e.g., a filled composite and / or a fiber-reinforced composite), a laminate material, or a mixture thereof. The topcoat can include at least one of a resin, a thermosetting polymer, a thermoplastic polymer, an epoxy, a lacquer, a polyurethane, a polyester, or a combination of one or more thereof. For example, without limitation, the topcoat is polyurethane. The polyurethane topcoat prevents water from penetrating through the coating and enhances corrosion protection. The topcoat has a thickness of from about 2 mils to about 3 mils, such as from about 2.1 mils to about 2.9 mils, such as about 2 mils, about 2.1 mils, about 2.2 mils, about 2.3 mils, about 2.4 mils, about 2.5 mils, about 2.6 mils, about 2.7 mils, about 2.8 mils, about 2.9 mils, or about 3 mils. For example, without limitation, the topcoat has a thickness of from about 2 mils to about 3 mils and the primer has a thickness of from about 0.3 mils to about 2.5 mils.

[0052] Sol-gel system

[0079] FIG. 1 is a side view of a corrosion-inhibiting sol-gel disposed on a substrate. The corrosion-inhibiting sol-gel system 100 includes a sol-gel 102 disposed on a material substrate 104. The sol-gel 102 has corrosion-inhibiting properties that provide corrosion protection for the material substrate 104. The sol-gel 102 promotes adhesion between the metal substrate 104 and the secondary layer 106. The secondary layer 106 can be a sealant, an adhesive, a primer, or a paint that can be deposited on the sol-gel 102, for example, by spray drying.

[0053]

[0080] The material substrate 104 can be any suitable material described herein and / or can include any suitable structure that benefits from the sol-gel 102 deposited thereon. The material substrate 104 can define one or more components (e.g., structural or mechanical components) of a device exposed to the environment, such as an aircraft, a ship, a spacecraft, a land vehicle, a device, a civil structure, a fastening component, a wind turbine, and / or other devices susceptible to environmental degradation. The material substrate 104 can be part of a larger structure such as a vehicle component. The vehicle component can be any suitable component of the vehicle, such as a structural component such as a landing gear, a panel, or a joint of an aircraft. Examples of vehicle components include rotor blades, landing gear, auxiliary power units, aircraft noses, fuel tanks, tail cones, panels, coated lap joints between two or more panels, wing-body assemblies, aircraft structural composites, fuselage joints, rib-skin joints, and / or other internal components. The material substrate 104 can be made of at least one of aluminum, aluminum alloy, magnesium, magnesium alloy, nickel, iron, iron alloy, steel, titanium, titanium alloy, copper and copper alloy, and glass / silica and other inorganic or mineral substrates. The material substrate 104 is made of steel. The material substrate 104 can be a "naked" substrate (unplated metal) having no plating, conversion coating and / or corrosion protection between the material substrate 104 and the sol-gel 102. Additionally or alternatively, the material substrate 104 can include surface oxidation and / or hydroxylation. Thus, the sol-gel 102 cannot directly bond to the material substrate 104 and / or the surface oxide layer on the surface of the material substrate 104. The material is not water-sensitive, but the sol-gel disposed on the material can protect other adjacent structures that may be susceptible to water sensitivity.

[0054]

[0081] The secondary layer 106 is disposed on the second surface 110 of the sol-gel 102, opposite to the first surface 108 of the sol-gel 102. The sol-gel 102 has a thickness smaller than the thickness of the material substrate 104. The sol-gel 102 has a thickness of from about 50 nm to about 4 μm, for example, from about 100 nm to about 2.5 μm, such as about 100 nm, about 200 nm, about 300 nm, about 400 nm, about 500 nm, about 600 nm, about 700 nm, about 800 nm, about 900 nm, about 1 μm, about 2 μm, or about 2.5 μm. The thinner the coating, the fewer defects it has (the higher the likelihood of no defects), and the thicker the coating, the more wear protection, electrical protection, and / or thermal protection it can provide to the underlying material substrate 104.

[0055]

[0082] The secondary layer 106 includes an organic material (e.g., an organic chemical composition) configured to bind and / or adhere to the sol-gel 102. The secondary layer 106 includes a paint, a primer, a topcoat, a polymer coating (e.g., an epoxy coating and / or a urethane coating), a polymer material, a composite material (e.g., a filled composite material and / or a fiber-reinforced composite), a laminated material, or a mixture thereof. The secondary layer 106 includes at least one of a polymer, a resin, a thermosetting polymer, a thermoplastic polymer, an epoxy, a lacquer, a polyurethane, and a polyester. The secondary layer 106 can additionally include at least one of a pigment, a binder, a surfactant, a diluent, a solvent, fine particles (e.g., a mineral filler), a corrosion inhibitor, and a fiber (e.g., carbon, aramid, and / or glass fiber).

[0056]

[0083] The tertiary layer 112 is disposed on the proximal surface 114 of the secondary layer 106 opposite the second surface 110 of the sol-gel 102. The tertiary layer 112 includes an organic material (e.g., an organic chemical composition) configured to bond and / or adhere to the secondary layer 106. The tertiary layer 112 includes paints, primers, topcoats, polymer coatings (e.g., epoxy coatings and / or urethane coatings), polymer materials, composite materials (e.g., filled composites and / or fiber-reinforced composites), laminated materials, or mixtures thereof. The tertiary layer 112 includes at least one of polymers, resins, thermosetting polymers, thermoplastic polymers, epoxies, lacquers, polyurethanes, and polyesters. The tertiary layer 112 can additionally include at least one of pigments, binders, surfactants, diluents, solvents, microparticles (e.g., mineral fillers), corrosion inhibitors, and fibers (e.g., carbon, aramid, and / or glass fibers).

[0057] Method for forming a sol-gel

[0084] The method for forming a sol-gel of the present disclosure includes mixing a metal alkoxide, acetic acid, and an organic solvent, such as an anhydrous organic solvent, and subsequently stirring for about 1 minute to about 1 hour, such as about 30 minutes. Next, an additional organic solvent (e.g., about 1 vol% to 20 vol% of the organic solvent, such as 5 vol% based on the total volume) is added to the metal alkoxide / acetic acid mixture. Next, an organosilane is added to the mixture and stirred for about 1 minute to about 1 hour, such as about 30 minutes. A corrosion inhibitor is added to the mixture in an amount of about 3 wt% to about 15 wt% based on the mixture. The mixture can be deposited on a material substrate. The deposited mixture can be cured at ambient temperature or heated to increase the rate of curing / sol-gel formation.

[0058]

[0085] FIG. 2 is a flow diagram of a method 200 for forming a sol-gel 102. As shown in FIG. 2, the sol-gel 102 can be formed by mixing one or more sol-gel components. The sol-gel components include two or more of an organosilane, a metal alkoxide, an acid stabilizer, and a corrosion inhibitor in an amount from about 3 wt% to about 15 wt% based on the sol-gel. The sol-gel 102 is formed by curing the mixed components 208.

[0059]

[0086] Generally, mixing 202 is performed by combining the sol-gel formulation components (e.g., dispersing, emulsifying, suspending, and / or dissolving) in an organic solvent, preferably an anhydrous organic solvent, and optionally by stirring the sol-gel formulation.

[0060]

[0087] Mixing 202 includes mixing the sol-gel components to form a mixture (e.g., a solution, a blend, an emulsion, a suspension, and / or a colloid). Mixing 202 includes mixing all of the sol-gel components together simultaneously. Alternatively, mixing 202 includes mixing any two components (e.g., a metal alkoxide and an acid stabilizer in an organic solvent) to form a first mixture, and then mixing the remaining components into the first mixture to form a second mixture. The first mixture and the second mixture each have a water content of from about 0.1 wt% to about 10 wt%, such as from about 0.1 wt% to about 5 wt%, such as from about 0.1 wt% to about 3 wt%, such as from about 0.1 wt% to about 1 wt%, such as from about 0.1 wt% to about 0.5 wt%, such as 0.5 wt% or less, such as 0.3 wt% or less, such as 0.1 wt% or less, such as 0 wt% based on the mixture.

[0061]

[0088] Mixing 202 may include dissolving, suspending, emulsifying, and / or dispersing the sol-gel component in an organic solvent before mixing with one or more of the other sol-gel components. Examples of solvents for dissolving, suspending, emulsifying, and / or dispersing the sol-gel component include one or more of alcohols (e.g., ethanol or propanol), ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, ethers (e.g., dimethyl ether or dipropylene glycol dimethyl ether, glycol ether, tetrahydrofuran (THF)), N-methyl-2-pyrrolidone (NMP), and dimethyl sulfoxide (DMSO).

[0062]

[0089] Additionally or alternatively, mixing 202 may include mixing one or more of the sol-gel components that are solids, aggregates, and / or powders with one or more of the other sol-gel components. For example, if mixing 202 includes mixing solids, powders, and / or viscous liquids, mixing 202 can include using a high-shear mixer (e.g., a paint shaker or a planetary stirrer or a stirrer) to mix. High-shear mixers can be advantageous for breaking up and / or finely dispersing solids to form a substantially homogeneous mixture. For example, high-shear mixers can dissolve, suspend, emulsify, disperse, homogenize, deaggregate, and / or disintegrate solids in the sol-gel formulation.

[0063]

[0090] The sol-gel component during mixing 202 can be diluted to control the self-condensation reaction, thereby extending the pot life of the mixed sol-gel formulation. Mixing 202 can include forming the weight percent by volume (wt%) of (metal alkoxide + organosilane + acid stabilizer in the mixture relative to the mixture) from about 0.1 wt% to about 30 wt%, such as from about 0.3 wt% to about 20 wt%, such as from about 1 wt% to about 10 wt%, such as from about 1 wt% to about 5 wt%, such as from about 2 wt% to about 4 wt%, such as from about 2 wt% to about 3 wt%, such as about 1 wt%, about 1.5 wt%, about 2 wt%, about 2.5 wt%, about 3 wt%.

[0064]

[0091] Mixing 202 may include forming the weight percentage by volume (wt%) of the corrosion inhibitor in the mixture to be from about 0.1 wt% to about 50 wt%, such as from about 0.2 wt% to about 40 wt%, such as from about 0.5 wt% to about 35 wt%, such as from about 1 wt% to about 30 wt%, such as from about 2 wt% to about 25 wt%, such as from about 3 wt% to about 15 wt%, such as about 4 wt%, about 5 wt%, about 7 wt%, about 10 wt%, about 15 wt%. The sol-gel formulation contains a corrosion inhibitor, and mixing 202 includes forming the weight percentage by volume (wt%) of (metal alkoxide + organosilane + acid stabilizer) in the mixture to be from about 0.3 wt% to about 50 wt%, such as from about 1 wt% to about 45 wt%, such as from about 2 wt% to about 40 wt%, such as from about 3 wt% to about 35 wt%, such as from about 4 wt% to about 25 wt%, such as from about 8 wt% to about 22 wt%, such as about 10 wt%, about 12 wt%, about 15 wt%.

[0065]

[0092] The volume ratio of organosilane to metal alkoxide in the sol-gel formulation during mixing 202 is from about 5% to about 20%, such as from about 9% to about 11%, and the metal alkoxide is pretreated with an acid. For example, without limitation, the volume ratio of organosilane to metal alkoxide may be about 5%, about 6%, about 7%, about 8%, about 9%, about 10%, about 11%, about 12%, about 13%, about 14%, about 15%, about 16%, about 17%, about 18%, about 19%, or about 20%, etc. A higher ratio can increase the % solids in the sol-gel coating and increase the concentration of the inhibitor mixed in the coating.

[0066]

[0093] During mixing 202, the corrosion inhibitor can have 90% of all the particles in the mixture, and (D90) has a diameter less than a particle size of from about 2 μm to about 5 μm, for example, about 2 μm, about 3 μm, about 4 μm, or about 5 μm. A smaller particle size can enable uniform mixing of the corrosion inhibitor within the mixture. The particle size can be referred to herein as the average particle size. The average particle size can be determined in commercially available classified products or by laser light scattering according to a plurality of methods, such as ISO4406.

[0067]

[0094] The mixture of the sol-gel components can be incubated 204 for a certain period, for example, from about 1 minute to about 60 minutes, for example, from about 5 minutes to about 30 minutes, for example, from about 10 minutes to about 20 minutes. Further, the pot life is the period from mixing until the sol-gel is formed (for example, until the mixture becomes too viscous to be used). The pot life can be from about 1 hour to about 24 hours, for example, from about 2 hours to about 8 hours, for example, about 4 hours. Incubating 204 can be carried out under ambient conditions (for example, room temperature) and / or at a high temperature. Suitable incubation temperatures include from about 10 °C to about 100 °C, for example, from about 20 °C to about 70 °C, for example, from about 30 °C to about 50 °C, for example, about 40 °C.

[0068]

[0095] Method 200 includes coating the material substrate 104 with a mixture containing a sol-gel component 206 and incubating the mixture 204. Incubating 204 includes leaving the mixture containing the sol-gel component standing at room temperature for about 30 minutes or more after mixing the mixture containing the sol-gel component. Coating 206 can include wetting the material substrate 104 with the mixture containing the sol-gel component, for example, by spraying, dipping, brushing and / or wiping the mixture containing the sol-gel component onto the material substrate 104. For example, suitable forms of spraying include spray guns, high volume low pressure spray guns and / or hand pump sprays. The mixture containing the sol-gel component can be drained from the wet material substrate 104 for several minutes (e.g., 1 to 30 minutes, 1 to 10 minutes or 3 to 10 minutes), and the excess undrained mixture can be absorbed from the material substrate 104 and / or gently blown off the material substrate 104 by compressed air as needed.

[0069]

[0096] Coating 206 includes cleaning and / or pretreating the material substrate 104 before wetting the material substrate with the mixture containing the sol-gel component. The metal substrate can be pretreated by immersing the metal substrate in a solution maintained at pH 3.7 to 3.95 using 1N H 2 SO 4 or 1N NaOH. The solution can include about 3 grams / liter to about 22 grams / liter of a water-soluble trivalent chromium salt, about 1.5 grams / liter to about 11.5 grams / liter of an alkali metal hexafluorozirconate, about 0 grams / liter (e.g., 0.1 grams / liter) to about 10 grams / liter of a water-soluble thickening agent, and about 0 grams / liter (e.g., 0.1 grams / liter) to about 10 grams / liter of a water-soluble surfactant selected from the group consisting of nonionic surfactants, anionic surfactants, cationic surfactants, and combinations thereof per liter of solution.

[0070]

[0097] Generally, sol-gel 102 adheres and / or bonds better to a clean, bare material substrate that is substantially free of dirt, non-reactive surface oxides, and / or corrosion products, and preferably has a sufficient concentration of reactive hydroxyl groups or other chemically reactive species aggregated thereon. Methods for preparing the surface of the material substrate can include degreasing, alkaline cleaning, chemical etching, chemical deoxidation, mechanical deoxidation (e.g., sanding and / or polishing), and / or other suitable approaches for creating a sol-gel compatible surface. Coating 206 generally does not include coating the metal substrate 104 with an undercoat or forming a conversion coating on the metal substrate 104, unless a coating is applied to improve compatibility with the sol-gel, such as on a substrate rich in hydroxyl groups or by other means. The surface of the material substrate can be made hydroxyl-rich by depositing silica hydroxide on the material surface.

[0071]

[0098] The method of the present disclosure includes curing a mixture containing a sol-gel component. As shown in FIG. 2, curing 208 can include drying a mixture containing a sol-gel component disposed on the material substrate 104, and can be carried out under ambient conditions at room temperature and / or elevated temperature. The curing temperature is from about 10°C to about 150°C, such as from about 30°C to about 100°C, such as from about 50°C to about 90°C, such as about 60°C, about 70°C, about 80°C. Curing 308 can be carried out for a certain period, such as from about 1 minute to about 48 hours, such as from about 5 minutes to about 24 hours, such as from about 10 minutes to about 8 hours, such as from about 30 minutes to about 4 hours, such as about 1 hour.

[0072]

[0099] After coating 206 and / or curing 208, the sol-gel is suitable for exposure to the external environment and / or application of the secondary layer 106. As shown in FIG. 2, before the curing 208 is completely finished, depositing 210 of the secondary layer 106 of the organic material can be carried out. For example, depositing 210 of the secondary layer 106 is carried out at least partially simultaneously with curing 208. Depositing 210 may include applying, spraying, dipping, contacting, adhering, and / or bonding the sol-gel 102 to the organic material to form the secondary layer 106. The secondary layer may include a primer, paint, fiber reinforced plastic, or other suitable organic material.

[0073]

[0100] After coating 210, the sol-gel is suitable for exposure for applying the tertiary layer 112. Depositing 212 may include applying, spraying, dipping, contacting, adhering, and / or bonding the secondary layer 106 to the organic material to form the tertiary layer 112. The tertiary layer may include paint, fiber reinforced plastic, or other suitable organic material.

Example

[0074]

[0101] FIG. 3 shows a potentiodynamic scan of a metal surface coated by pretreatment with a sol-gel. Comparative example 3 is a bare metal surface. Comparative example 2 is a metal panel coated with a sol-gel film containing 3 vol.% of the components. Comparative example 1 is a metal panel coated with a sol-gel film containing >3% vol.% of the components. The sol-gel of the present invention is a metal panel coated with a sol-gel film containing >3 vol.% of the components + a corrosion inhibitor.

[0075]

[0102] Increasing the vol% of the components of the sol-gel increased the coating weight / coating thickness, thereby increasing the passivation of the film on the metal surface. By increasing the thickness in this way, the corrosion current decreased.

[0076]

[0103] The inhibitor had cathodic inhibition characteristics, which shifted the potential towards negative values and significantly reduced the corrosion current.

[0077]

[0104] As shown in Figure 4, the corrosion inhibitor of Experimental Example 1 having 1,2,4-DMcT provided the strongest corrosion inhibition compared to other organic inhibitors or chromate inhibitors. The current value was monitored at -0.8 V from the potential-current scan of the inhibitor dissolved in the electrolyte with the metal surface as the working electrode. The current at -0.8 V indicated the redox reaction occurring on the metal surface. The lower the value of ORR, the greater the effect of the inhibitor, for example, the efficiency of the inhibitor increased.

[0078]

[0105] Figure 5 shows the current-voltage graph on the surface of the electrode. The current was -0.8 V with respect to the ORR on the metal surface. Although not bound by theory, the suppression of the ORR current was considered to be due to the action of the inhibitor, which is a reaction of the inhibitor with the metal surface. Although not bound by theory, in the case of thiol inhibitors, the inhibitor is generally known to bind to copper-rich sites on the surface of metal alloys. The corrosion inhibition of Inhibitor 1, Inhibitor 2, Inhibitor 3, and Inhibitor 4 having a corrosion inhibitor of about 3 wt% to about 15 wt% exhibited better inhibitor efficiency compared to the comparative example without a corrosion inhibitor.

[0079]

[0106] As shown in Figures 6A and 6B of the present disclosure, the metal substrate can be coated with the corrosion-resistant sol-gel. The layer of the corrosion-resistant sol-gel can be made thin, and as shown in Figure 6A, the thin layer can reduce the defects in the sol-gel. The layer of the corrosion-resistant sol-gel can be made thick, and as shown in Figure 6B, the thick layer can improve the adhesion of the sol-gel to the material substrate, the primer, or the topcoat.

[0080]

[0107] As shown in Figure 7, the average thickness of the sol-gel of the present disclosure is between 100 nm and 4 μm. As shown in Figure 8, the average coating weight of the present disclosure is 40 mg / ft 2 and 400 mg / ft2 It is between. As shown in FIGS. 9 and 10, by increasing the weight of the sol-gel coating, barrier properties such as absorption and passivation can be improved.

[0081]

[0108] As shown in FIG. 11, the electrical contact resistance increased as the coating thickness and weight increased. Three sample formulations of the corrosion-resistant sol-gel with an increased vol% of the components in the sol-gel were prepared, and the amount of inhibitor added to the film was increased as it progressed from formulation #1 to formulation #2 and then to formulation #3. When the vol% of the sol-gel components and the inhibitor in the sol-gel was increased, the coating weight and thickness of the film increased. Compared with formulation #1, the corrosion resistance in the salt spray chamber was improved for formulation #1. However, as the film thickness increased, the surface contact resistance value also increased.

[0082]

[0109] FIG. 12 shows the impedance of the coating panel as a function of the frequency of the applied AC current. The fully chromated laminate (chromate conversion coating (CCC) + chromate primer) has the highest impedance, while the pretreatment without inhibitor + chromate primer or the pretreatment with inhibitor + non-chromate primer has medium impedance, and finally, the CCC + non-chromate primer or the pretreatment without primer + non-chromate primer has the lowest impedance. Without being bound by theory, by adding an inhibitor to the pretreatment, the overall impedance of the film increased (synonymous with improved corrosion resistance), thereby improving the performance of the non-chromate primer. As shown in A to F of FIG. 13, when the material substrate was coated with the corrosion-resistant sol-gel of the present disclosure, corrosion was reduced compared with the comparative sol-gel.

[0083]

[0110] As shown in A - C of FIG. 14, the corrosion resistance of the disclosed chromate - free corrosion - resistant sol - gel was equivalent to that of the sol - gel coated with a chromate corrosion inhibitor. Test pieces of a coastal corrosion test exposed outdoors for 9 months were monitored for corrosion resistance. The chromate stack shown in A of FIG. 14 was compared with the pretreatment with a non - chromate primer stack shown in B and C of FIG. 14 using a corrosion - resistant sol - gel. As shown in A - C of FIG. 14, for all test pieces, good corrosion resistance with no surface swelling or corrosion of the scribed lines was observed.

[0084]

[0111] As shown in Table 1, when the material substrate was coated with the corrosion - resistant sol - gel of the present disclosure, no influence on the adhesiveness of the paint was observed. Table 1. Adhesion characteristics of sol - gel - coated material substrates TIFF2025516507000008.tif91170

[0085]

[0112] Preparation of corrosion - resistant sol - gel

[0113] The "Part A" solution was prepared by adding 22 mL of glacial acetic acid (GAA, Fischer Scientific) to 50 mL of zirconium propoxide (TPOZ, Acros Organics). Care was taken to ensure that all glassware was completely dry to avoid the formation of zirconium hydroxide. The resulting solution was clear and bright yellow. After allowing the solution to stand for 10 minutes, 1000 mL of Milli - Q water was added. This Part A solution was used for all test matrices.

[0086]

[0114] Next, 10.8 mL of glycidoxypropyltrimethoxysilane (GTMS, Acros Organics) was added to 108 mL of Part A in a ThinkyTM planetary mixer container, mixed thoroughly, and allowed to stand for 30 minutes. Then, 0.6 mL of a 10% by volume aqueous solution of Antarox BL-204 (Solvay) was added in an aqueous solution, followed by the addition of an inhibitor. Then, 2 mm borosilicate glass beads were added to the Thinky cup to cover the bottom. Then this solution was mixed in a ThinkyTM planetary mixer. (Step 1 - 500 RPM for 30 seconds, Step 2 - 1000 RPM for 30 seconds, Step 3 - 1500 RPM for 1 minute.)

[0087]

[0115] Inhibitor to be evaluated

[0116] Two inhibitors - HALOX® SZP-391 JM and HALOX® 430 JM were obtained from AICL advanced additives. Both inhibitors were jet milled materials with an average particle size of ~3 microns and a D99 of ~8 microns.

[0088]

[0117] Inhibicor® 1000 and Hybricor® 204 were obtained from WPC technologies. Multiple versions of Inhibicor® 1000 were tested as described in the Results and Discussion section.

[0089]

[0118] 2,5-Dimercapto-1,3,4-thiadiazole (DMCT) was obtained from Acros Organics; sodium benzoate and cerium nitrate were obtained from Sigma Aldrich. These compounds were used as received.

[0090]

[0119] Pre - cleaning of the panel

[0120] All 7075-T6 panels were cleaned as follows: degreased with Brulin 815GD for 10 minutes, followed by alkaline cleaning with Bonderite C-AK for 12 minutes, and deoxidized in a Nitric / HF solution for 10 minutes.

[0091]

[0121] The 7178-T6 panels were grit blasted with 180 grit brown fused alumina to remove all residual coatings. The panels were then cleaned as described above for the 7075 panels.

[0092]

[0122] Application of Conversion Coatings and Pretreatments

[0123] The various pretreatments and conversion coatings evaluated were SurTec's SurTec 650V (trichromate passivation), Henkel's Alodine 5900 (tri-chromate), Henkel's Alodine 1200S (hexavalent chromium conversion coating), and corrosion resistant sol-gel (-1 and -2).

[0093]

[0124] The SurTec coating was applied using a dipping process. The solution was prepared using a 5%vol. concentration in an aqueous solution. The solution was maintained in the pH range of 3.7 - 3.95 using 1N H 2 SO 4 or 1N NaOH. The cleaned panels were dipped in the SurTec 650V tank for 3 minutes, followed by rinsing with tap water for 15 - 30 seconds, 2 to 3 times, and then rinsing with deionized water for 15 seconds. The panels were then dried using compressed air. After drying, the coating was clean and transparent.

[0094]

[0125] The Alodine 5900 coating was applied onto the panel with a brush using the 5900 solution. To apply the coating with a brush, the cleaned panels were arranged in the draft, the solution was applied with a brush, and the surface was kept wet for 3 minutes. Subsequently, rinsing with tap water for 15 - 30 seconds was carried out 2 to 3 times, and rinsing with deionized water for 15 seconds was carried out once. Then the panel was dried in an oven at 100 - 120°F for 1 hour. After drying, the coating was clean and bluish.

[0095]

[0126] The Alodine 1200S coating was applied onto the panel with a brush. To apply the coating with a brush, the cleaned panels were arranged in the draft, the solution was applied with a brush, and the surface was kept wet for 3 minutes. Subsequently, rinsing with tap water for 15 - 30 seconds was carried out several times, and rinsing with deionized water for 15 seconds was carried out once. Then the panel was dried in an oven at 100 - 120°F for 1 hour. After drying, the coating had a golden color.

[0096]

[0127] The corrosion - resistant sol - gel of the present disclosure was formulated and applied using a conventional HVLP gun, and then dried overnight at room temperature.

[0097]

[0128] Application of the primer and top - coat

[0129] All primers and top - coats were applied the day after the panels were pretreated using the above - mentioned pretreatment. Both the primer and the top - coat were applied using a conventional HVLP gun. The top - coat was applied within a 4 - hour window after the application of the primer, and the coating was cured at room temperature for 2 weeks. After this 2 - week drying time, the panel was scored using a wide - tool cutter. The thicknesses of the primer and top - coat were measured from witness test specimens sprayed simultaneously with the panel. The thicknesses of the primer and top - coat were measured and recorded using a handheld Elcometer thickness gauge.

[0098]

[0130] Test matrix

[0131] Multiple corrosion-resistant sol-gel formulations were evaluated according to a novel accelerated cyclic test method developed by ASTM B117 and BR&T4 using the test matrix described below. BLIS 18-00512 compared the corrosion-resistant sol-gel formulations to a control and an alternative trivalent chromium pretreatment. BLIS 18-00614 evaluated the corrosion resistance of lower wt.% of DMCT and Inhibicor 1000 alone in an aqueous solution. BLIS 18-00512-2 re-evaluated the sol-gel system described herein against 3000 hours of exposure of ASTM B117.

[0099]

[0132] Coating delamination

[0133] Coating and delamination

[0134] The coating was removed from BLIS 18-00512-2 of the test matrix using Bonderite Turco S-ST 5351, a methylene chloride-based stripper. To remove the coating, the panel was immersed in the stripper overnight (approximately ~6 hours). The efficiency of the stripper was recorded.

[0100]

[0135] Screening of inhibitors in corrosion-resistant sol-gel - Corrosion protection alone

[0136] The chemical properties of multiple inhibitors were evaluated in the modified sol-gel formulations as shown in Table 2. Table 2. Inhibitors screened for single protection of 7075-T6, 24-hour exposure B117 TIFF2025516507000009.tif69170

[0101]

[0137] When tested with a 2 wt.% loading of a corrosion inhibitor in the sol-gel, HALOX® SZP-391 JM containing a corrosion-resistant sol-gel had better corrosion performance than HALOX® 430 JM corrosion-resistant sol-gel. After 336 hours of exposure in the NSS chamber, corrosion was suppressed when the sol-gel was loaded with 1.24 wt.% of the corrosion inhibitor. Some corrosion products were visible at the bottom of the panel due to the aggregation of the inhibitor during drying. There was an improvement over the non-neutralized Inhibicor® 1000 (with a larger particle size) containing corrosion-resistant sol-gel formulation with 0.53 wt.% of the corrosion inhibitor added to the sol-gel, where extensive corrosion occurred after 120 hours of exposure in the NSS chamber.

[0102]

[0138] When testing the case of loading 1.24%wt. of the corrosion inhibitor in the sol-gel and the case of loading 2.17 wt.% of the corrosion inhibitor in the sol-gel, the DMCT formulation of the corrosion-resistant sol-gel was soluble in the modified sol-gel and had improved corrosion resistance alone. At 1.24 wt% DMCT, no corrosion products were visually observed after 336 hours of the single corrosion test.

[0103]

[0139] Evaluation of Aluminum and Lithium-Rich Primer in Corrosion-Resistant Sol-Gel Formulation

[0140] A - F in Figure 15 show the results of a corrosion-resistant sol-gel containing non-neutralized micronized Inhibicor® 1000 coated with an aluminum (Al)-rich (Av-dec) and lithium (Li)-rich primer (Akzo Nobel Aerodur 2118). After 2000 hours of exposure in the NSS chamber, the panel containing the Al-rich primer showed some swelling on the surface, and both primers had white salts at the scribe lines.

[0104]

[0141] The corrosion-resistant sol-gel containing DMCT also had exceptional corrosion performance after 2000 hours of exposure to NSS when coated with an Al-rich primer. The scribed lines were blackened, but there were no corrosion products. When coated with a lithium-rich primer, the corrosion resistance of the corrosion-resistant sol-gel containing DMCT was low.

[0105]

[0142] The corrosion-resistant sol-gel formulation containing unneutralized micronized Inhibicor® 1000 and DMCT was further tested in a new accelerated salt spray corrosion test developed by Chem Tech, BR&T (Seattle).

[0106]

[0143] 3000-hour ASTM B117 corrosion test using the corrosion-resistant sol-gel formulation

[0144] 7075-T6 bare panel

[0145] Alodine 1200S

[0146] Regardless of the pretreatment used, the corrosion resistance of all 7075-T6 panels coated with primer RW-7171-64 was low. After 3000 hours of exposure to NSS, there were white salts and corrosion at the scribed lines and swelling on the surface. The swelling of panel A-1-1-3 appeared only after 2000 hours of exposure.

[0107]

[0147] As shown in A - D of FIG. 16, the 7075 - T6 panel coated with Alodine 1200S functioned well after 3000 hours of exposure when using Aerodur 2118 and PPG CA7231. The panel treated with Alodine 1200S and Li - rich Aerodur 2118 had some swelling at the scribed lines. The scribed lines of all the panels coated with Alodine had many local sites with white salts inside the scribed lines. After stripping the coating from panel A - 1 - (1 - 4) - 3, no corrosion was visually observed on the surface of any panel, including under the slight swelling of panel A - 1 - 1 - 3. The Truco stripper had problems stripping the Al - rich primer as was evident on panel A - 1 - 2 - 1, and with this stripper, the Alodine conversion coating was not removed from any panel. This stripper stripped the Li - rich primer and both PPG primers.

[0108]

[0148] Alodine 5900

[0149] As shown in A - D of FIG. 17, the tri - chrome pretreatment from Henkel Alodine 5900 had excellent performance when using the Aerodur 2118 Li - rich primer. The 7075 - T6 panels treated with Av - Dec Al - rich and PPG CA7231 had swelling at the scribed lines. Almost the entire surface of panel A - 2 - 1 - 3 was covered with small swellings.

[0109]

[0150] Under the small swellings on the surface of panel A - 2 - 1 - 3, a dark staining of Al was visually observed. All the large swellings on the scribed lines had pitting traces under the coating. The swellings on panels A - 2 - 1 - 3 and A - 2 - 4 - 3 appeared after 1000 hours of NSS exposure.

[0110]

[0151] The Turco stripper could not strip the Li - rich primer from panel A - 2 - 3 - (1 - 2), but it could strip the PPG and Av - Dec primers.

[0111]

[0152] SurTec 650V

[0153] As shown in A - D of FIG. 18, SurTec 650V exhibited corrosion resistance and compatibility with Av - Dec, Aerodur 2118, and CA7231 undercoats. After 3000 hours of exposure, none of these panels had any swelling on the surface. However, for Av - Dec and CA7231 undercoats, small swelling and pitting were observed at the scored lines directly under the coating. The surface of panel A - 3 - 1 - 3 was covered with small swelling after 2000 hours of NSS exposure, but there were no traces of corrosion under the swelling.

[0112]

[0154] All the swelling of panel A - 3 - (1 - 4) - 3 appeared after 2000 hours of NSS exposure. Except for Aerodur 2118, the other undercoats were peeled off by Turco stripper.

[0113]

[0155] Corrosion - resistant sol - gel

[0156] As shown in A - D of FIG. 19, the pretreatment with corrosion - resistant sol - gel exhibited corrosion resistance to Av - Dec Al - rich undercoat. The panels treated with corrosion - resistant sol - gel, Aerodur 2118, and CA7231 had large swelling and white salts at the scored lines. Panel A - 4 - 1 - 3 with RW7171 - 64 coating had severe swelling on the surface and at the scored lines.

[0114]

[0157] The swelling on the scored lines in all the panels coated with the pretreatment by corrosion - resistant sol - gel - 2 was visible after 1000 hours of NSS exposure, and this swelling and corrosion deteriorated as the exposure time extended. Turco stripper was not very useful for peeling off the undercoat from the panels pretreated with corrosion - resistant sol - gel - 2. After peeling off the undercoat from panel A - 4 - (1 - 4) - 3, there was no corrosion under the swelling observed on the surface, but the swelling adjacent to the scored lines had pitting directly under the paint.

[0115]

[0158] 7178 panel

[0159] Alodine 1200S

[0160] The panels treated with Alodine 1200S chromate corrosion inhibitor exhibited corrosion performance on RW-7171-64 primer and Aerodur 2118 primer. As shown in A - D of Figure 20, the panels treated with Alodine 1200S and Av-Dec had some white salts within the scored lines, and the primer CA7231 had some swelling under the primer along the scored lines and a large amount of white salts within the scored lines.

[0116]

[0161] None of these primers could be successfully peeled from Panel B-1-(1-4)-1 with Truco stripper. The swelling on the scored lines had pitting directly under the paint.

[0117]

[0162] Alodine 5900

[0163] As shown in A - C of Figure 21, the panels coated with Aerodur 2118 and RW7171-64 had the minimum creepage distance with the salts within the scored lines. The panels coated with Av-Dec Al-rich primer had the salts within the scored lines and some swelling under the primer along the scored lines. When the coatings were removed from these panels, pitting could be visually observed under the swelling along the scored lines.

[0118]

[0164] Truco stripper could not peel Panel B-2-1-(1-2) treated with PPG RW-7171-64 primer. The Al-rich primer was removed from the stripper after 1500 hours of exposure, but this primer could not be peeled after 3000 hours of exposure.

[0119]

[0165] SurTec 650V

[0166] As shown in A to C of FIG. 22, in SurTec 650V using an Av-Dec Al-rich undercoat, the salt in the scored lines was minimal and there was no swelling on the panel. The panel coated with Aerodur 2118 had salt in the scored lines, and RW7171-64 had salt in the scored lines and some swelling along the scored lines. Pitting was evident directly below the swelling on the scored lines of these panels. RW-7171-64 and the Av-Dec Al-rich undercoat were not removed with the Truco stripper.

[0120]

[0167] Corrosion-resistant sol-gel-2

[0168] As shown in A and B of FIG. 23, the corrosion-resistant sol-gel-coated panel with an Av-Dec Al-rich undercoat had small swellings. There were salt in the scored lines and some swelling along the scored lines. In the case of panel B-4-2-2, corrosion was not visible directly below the surface swelling, but the swelling adjacent to the scored line had pitting directly below the undercoat.

[0121]

[0169] The corrosion-resistant sol-gel-coated panel with an RW 7171-64 undercoat exhibited swellings of ~1 / 16 and had white salt and swellings in the scored lines. However, pitting was present only directly below the swelling on the scored line under the undercoat, and none of the surface swellings had corrosion directly below the undercoat.

[0122]

[0170] The Truco stripper did not remove the undercoat on these panels pretreated with the corrosion-resistant sol-gel-2.

[0123]

[0171] Ranking of 7075-T6 and 7178 Al panels after NSS corrosion test

[0172] As shown in FIGS. 24 and 25, after the corrosion test, the ranking of the coated 7075-T6 and 7178 Al panels was carried out using methods #1 and #2 described below.

[0124]

[0173] Ranking by method #1

[0174] Based on the comparison of the corrosion performance with that of other panels in the set, the panels were ranked according to their corrosion performance.

[0125]

[0175] Each panel was evaluated for 1 to 15 as shown in Table 3 based on the appearance of the scribed line, the amount of white salt (corrosion product) within the scribed line, the bulge along the scribed line, and the bulge at a position away from the scribed line. As shown in Table 4, the evaluation of the scribed line was based on the creepage distance from the scribed line measured in inches.

[0126]

[0176] Panels within a group containing the same pretreatment (and different primers) were numerically evaluated from 1 to 2, 3, or 4, with 1 being the best and 4 being the worst candidate. The 7075-T6 Al panels were evaluated after 1000 hours, 2000 hours, and 3000 hours of exposure, and the 7178 panels were evaluated after 1500 hours and 3000 hours of exposure.

[0127]

[0177] SurTec 650V panels coated with Aerodur 2118, AvDec PT27703, AvDec GK15-002E1, and PPG CA7231 exhibited corrosion resistance characteristics for up to 9 months after application. The corrosion-resistant sol-gel of the present disclosure coated with AvDec GK15-002E1 exhibited corrosion resistance characteristics for up to 9 months after application. Table 3. Determination of Corrosion Evaluation by Method #1 TIFF2025516507000010.tif95170Table 4. Determination of Scribed Line Evaluation by Method #1 TIFF2025516507000011.tif46170

[0128]

[0178] Ranking by Method #2

[0179] Each panel was assigned an independent score regardless of the performance of other panels within the test matrix. The scores / rankings for Method #2 were determined using three factors: 1) evaluation of general corrosion (GC), 2) evaluation of the size of bulges (BS), and 3) evaluation of the frequency of bulge occurrence (BF). Each 7075-T6 panel that completed exposures at 1000 hours, 2000, and 3000 hours was assigned a numerical value for each of the three criteria, and the total score was calculated using Equation (1) below.

[0129]

[0180] According to Equation 1 below, weighting was applied to the scores determined at each interval such that the longer the exposure time, the greater the weighting. The score at 1000 hours was multiplied by 0.2, the score at 2000 hours was multiplied by 0.3, and the score at 3000 hours was multiplied by 0.5. These weighted scores were then summed and the sum was divided by 2 to obtain the final Method #2 score for each panel. TIFF2025516507000012.tif23170

[0130]

[0181] The general corrosion evaluation was determined based on the observation of pitting around the scribed lines and on the surface of the detached panel. The panel with the least corrosion was assigned the highest value of 10, and the panel with the most severe corrosion was assigned the lowest value of 2.

[0131]

[0182] For the size and frequency of bulges, scores were assigned based on the size and density of the bulges observed on both the surface and the scribed lines of the coated panel. A bulge occurrence frequency score of 1 was assigned to panels with no bulges.

[0132]

[0183] The weighting scheme for the composite score for the 7178-T6 panel was changed due to only two intervals (1500 hours and 3000 hours) instead of three (1000 hours, 2000 hours, and 3000 hours) in the case of 7075-T6.

[0133]

[0184] For the 7178-T6 panel, the score after 1500 hours of exposure was multiplied by 0.33, and the score after 3000 hours of exposure was multiplied by 0.67. Similar to the previous time, these two scores were summed and the total was divided by 2 to obtain the final score.

[0134]

[0185] To determine the size and frequency of blistering, the same criteria as for the 7075-T6 panel were applied to the 7178 panel.

[0135]

[0186] Comparison of Corrosion Resistance of Coated 7075-T6 and 7178 Al Panels after NSS and Cyclic Accelerated Corrosion Tests

[0187] By scoring method #2, it was possible to compare the corrosion performance of similar coating laminates between two different accelerated corrosion tests.

[0136]

[0188] As shown in FIGS. 26 and 27, extremely different performances were observed for the corrosion-resistant sol-gel-2 containing the paint laminate. The corrosion-resistant sol-gel-2 / Av-Dec Al-rich coating provided corrosion resistance under cyclic accelerated corrosion test conditions but not under the ASTM B117 test.

[0137]

[0189] After the ASTM B117 test, a similar effect was observed for the magnesium (Mg)-rich primer. It was observed that the Mg-rich primer exhibited corrosion resistance in outdoor exposure and actual test conditions but not in the accelerated corrosion test (under ASTM B117 conditions). In outdoor exposure, a passive MgCO 3 layer that provided corrosion protection for both the anode and cathode was formed. However, upon exposure to ASTM B117 conditions, a thin and porous Mg(OH) 2 layer with low corrosion performance was formed.

[0138] Additional Aspects

[0190] The present disclosure provides, among other things, the following examples, each of which may optionally be considered to include any other aspect and combinations thereof.

[0139] Clause 1. A coated substrate comprising a metal substrate; a sol-gel coating disposed on the metal substrate, the sol-gel coating comprising a sol-gel containing a corrosion inhibitor, a surfactant, and a reaction product of an organosilane, a metal alkoxide, and an acid; and an organic primer coating having a plurality of metal particles disposed on the sol-gel coating.

[0140] Clause 2. The coated substrate of Clause 1, wherein the corrosion inhibitor has two or more thiol moieties. Clause 3. The coated substrate of Clause 1 or 2, wherein the metal is selected from the group consisting of lithium, aluminum, magnesium, salts thereof, cations thereof, and combinations thereof.

[0141] Clause 4. The coated substrate according to any one of Clauses 1 to 3, wherein the metal is aluminum, a salt thereof, or a cation thereof.

[0142] Clause 5. The coated substrate according to any one of Clauses 1 to 4, wherein the metal is a combination of aluminum, a salt thereof, or a cation of aluminum and magnesium, a salt thereof, or a cation of magnesium. Clause 6. The coated substrate according to any one of Clauses 1 to 5, wherein the organic primer is polysiloxane or epoxy.

[0143] Clause 7. The coated substrate according to any one of Clauses 1 to 6, wherein the epoxy is an amine-cured epoxy. Clause 8. The coated substrate according to any one of Clauses 1 to 7, wherein the surfactant is ethylene-oxide alcohol, propylene-oxide alcohol, or ethylene-oxide-propylene-oxide alcohol. Clause 9. The coated substrate according to any one of Clauses 1 to 8, further comprising an organic topcoat disposed on the primer coating.

[0144] Clause 10. The coated substrate according to any one of Clauses 1 to 9, wherein the organic topcoat is polyurethane. Article 11. A coated substrate according to any one of Articles 1 to 10, wherein the organic topcoat has a thickness of from about 2 mils to about 3 mils and the organic undercoat coating has a thickness of from about 0.3 mils to about 2.5 mils.

[0145] Article 12. A coated substrate according to any one of Articles 1 to 12, wherein the corrosion inhibitor is mercapto thiadiazole. Article 13. A coated substrate according to any one of Articles 1 to 13, wherein the dimercapto thiadiazole is 2,5-dimercapto-1,3,4-thiadiazole.

[0146] Article 14. A coated substrate according to any one of Articles 1 to 13, wherein the metal substrate is an aluminum substrate.

[0147] Article 15. A coated substrate according to any one of Articles 1 to 14, wherein the aluminum substrate is a 7075-T6 aluminum substrate or a 7178 aluminum substrate. Article 16. A coated substrate according to any one of Articles 1 to 15, wherein the sol-gel coating has a thickness of from about 50 nm to about 4 microns.

[0148] Article 17. A coated substrate according to any one of Articles 1 to 16, wherein the sol-gel coating has a thickness of from about 100 nm to about 2.5 microns.

[0149] Article 18. A coated substrate according to any one of Articles 1 to 17, wherein the sol-gel coating has a weight of from about 30 mg / ft 2 to about 400 mg / ft 2 . Article 19. A coated substrate according to any one of Articles 1 to 18, wherein the sol-gel coating has a weight of from about 250 mg / ft 2 to about 1000 mg / ft 2 , for example from about 250 mg / ft 2 to about 350 mg / ft 2 .

[0150] Clause 20. A coated substrate according to any one of Clauses 1 to 19, wherein the metal particles of the plurality of metal particles have an average particle size of from about 1 micron to about 100 microns, such as from about 20 to about 30 microns, or alternatively from about 30 microns to about 40 microns. Clause 21. A coated substrate according to any one of Clauses 1 to 20, wherein the sol-gel coating has a concentration of corrosion inhibitor of from about 1 wt% to about 3 wt% based on the volume of the sol-gel coating.

[0151] Clause 22. A coated substrate according to any one of Clauses 1 to 20, wherein the sol-gel coating has a concentration of corrosion inhibitor of from about 3 wt% to about 15 wt% based on the volume of the sol-gel coating.

[0152] Clause 23. A coated substrate according to any one of Clauses 1 to 22, wherein the sol-gel coating has a concentration of corrosion inhibitor of from about 10 wt% to about 15 wt% based on the volume of the sol-gel coating.

[0153] Clause 24. A coated substrate according to any one of Clauses 1 to 23, wherein the organosilane is glycidoxypropyltrimethoxysilane, the acid is acetic acid, and the metal alkoxide is zirconium propoxide. Clause 25. A method for preparing a coated substrate, comprising applying a sol-gel coating to a metal substrate to form a sol-gel coating, wherein the sol-gel coating contains a corrosion inhibitor; and applying an undercoat coating to the sol-gel coating to form an undercoat coating, wherein the undercoat coating contains a metal.

[0154] Clause 26. The method according to Clause 25, wherein applying the sol-gel coating includes mixing a corrosion inhibitor with an organosilane and a metal alkoxide, the volume ratio of the organosilane to the metal alkoxide is from about 5% to about 20%, and the metal alkoxide is pretreated with an acid. Clause 27. The method according to Clause 25 or 26, wherein the volume ratio of the organosilane to the metal alkoxide is from about 9% to about 11%.

[0155] Article 28. The method according to any one of Articles 25 to 27, wherein the metal of the primer coating is a plurality of metal particles independently selected from the group consisting of aluminum, lithium, magnesium, salts thereof, cations thereof, and combinations thereof.

[0156] Article 29. The method according to any one of Articles 25 to 28, wherein the corrosion inhibitor after mixing has a D90 particle size of from about 2 microns to about 5 microns. Article 30. The method according to any one of Articles 25 to 29, further comprising pretreating the metal substrate before applying the sol-gel coating to the metal substrate. Article 31. The pretreatment comprises immersing the metal substrate in a solution maintained at a pH of 3.7 to 3.95 using 1N H 2 SO 4 or 1N NaOH. The method according to any one of Articles 25 to 30. Article 32. The solution contains, per liter of solution, from about 3 grams to about 22 grams of a water-soluble trivalent chromium salt, from about 1.5 grams to about 11.5 grams of an alkali metal hexafluorozirconate, from about 0 grams to about 10 grams of a water-soluble thickening agent, and from about 0 grams to about 10 grams of a water-soluble surfactant selected from the group consisting of nonionic surfactants, anionic surfactants, cationic surfactants, and combinations thereof. The method according to any one of Articles 25 to 31.

[0157] Article 33. A coated substrate comprising a metal substrate; a sol-gel coating disposed on the metal substrate, the sol-gel coating comprising a corrosion inhibitor, a surfactant, and a sol-gel comprising a reaction product of an organosilane, a metal alkoxide, and an acid; and an organic primer, the organic primer coating disposed on the sol-gel coating, the organic primer coating comprising a plurality of metal particles.

[0158] Article 34. The coated substrate according to Article 33, wherein the corrosion inhibitor has two or more thiol moieties.

[0159] Clause 35. The coated substrate of Clause 33 or 34, wherein the metal is selected from the group consisting of lithium, aluminum, magnesium, their salts, their cations, and combinations thereof, and the metal is optionally aluminum, its salt, or its cation.

[0160] Clause 36. The coated substrate of any one of Clauses 33 to 35, wherein the organic primer is polysiloxane or epoxy, and the epoxy is optionally an amine-cured epoxy.

[0161] Clause 37. The coated substrate of any one of Clauses 33 to 36, wherein the surfactant is ethylene-oxide alcohol, propylene-oxide alcohol, or ethylene-oxide-propylene-oxide alcohol.

[0162] Clause 38. The coated substrate of any one of Clauses 33 to 37, wherein the corrosion inhibitor is mercapto thiadiazole, and the dimercapto thiadiazole is optionally 2,5-dimercapto-1,3,4-thiadiazole.

[0163] Clause 39. The coated substrate of any one of Clauses 33 to 38, wherein the sol-gel coating has a concentration of corrosion inhibitor of about 1 wt% to about 15 wt% based on the volume of the sol-gel coating.

[0164] Clause 40. The coated substrate of any one of Clauses 33 to 39, wherein the organosilane is glycidoxypropyltrimethoxysilane, the acid is acetic acid, and the metal alkoxide is zirconium propoxide.

[0165] Clause 41. A method for preparing a coated substrate, comprising applying a sol-gel coating to a metal substrate to form a sol-gel coating, wherein the sol-gel coating contains a corrosion inhibitor; and applying a primer coating to the sol-gel coating to form a primer coating, wherein the primer coating contains a metal.

[0166] Clause 42. The method of Clause 41, wherein applying the sol-gel coating comprises mixing a corrosion inhibitor with an organosilane and a metal alkoxide.

[0167] Clause 43. The method of Clause 41 or 42, wherein the volume ratio of the organosilane to the metal alkoxide is from about 5% to about 20%, the metal alkoxide is pretreated with an acid, and / or the volume ratio of the organosilane to the metal alkoxide is from about 9% to about 11%.

[0168] Clause 44. The method according to any one of Clauses 41 to 43, wherein the metal of the primer coating is a plurality of metal particles independently selected from the group consisting of aluminum, lithium, magnesium, their salts, their cations, and combinations thereof, and the corrosion inhibitor after mixing optionally has a D90 particle size of from about 2 microns to about 5 microns.

[0169] Clause 45. The method according to any one of Clauses 41 to 44, further comprising pretreating the metal substrate before applying the sol-gel coating to the metal substrate.

[0170] Clause 46. The method of Clause 45, wherein pretreating comprises immersing the metal substrate in a solution maintained at pH 3.7 to 3.95 using 1N H 2 SO 4 or 1N NaOH.

[0171] Clause 47. The method of Clause 47, wherein the solution contains, per liter of solution, from about 3 grams to about 22 grams of a water-soluble trivalent chromium salt, from about 1.5 grams to about 11.5 grams of an alkali metal hexafluorozirconate, from about 0 grams to about 10 grams of a water-soluble thickening agent, and from about 0 grams to about 10 grams of a water-soluble surfactant selected from the group consisting of nonionic surfactants, anionic surfactants, cationic surfactants, and combinations thereof.

[0172]

[0191] While preferred embodiments have been described, those skilled in the art will readily recognize alternative examples, variations, and modifications that can be made without departing from the concept of the present invention. Accordingly, based on this specification, the claims should be construed liberally to be supported by the full scope of equivalents known to those skilled in the art. The examples are illustrative of the present disclosure and are not intended to limit the present invention. Accordingly, the present disclosure is defined by the claims, and the claims are limited only as necessary in view of the relevant prior art.

Claims

1. A metal substrate, A sol-gel coating disposed on the metal substrate, A corrosion inhibitor, A surfactant, A sol-gel containing a reaction product of an organosilane, a metal alkoxide, and an acid; and An organic undercoat coating disposed on the sol-gel coating, the organic undercoat coating containing a plurality of metal particles A coated substrate comprising.

2. The coated substrate according to claim 1, wherein the corrosion inhibitor has two or more thiol moieties.

3. The coated substrate according to claim 1 or 2, wherein the metal is selected from the group consisting of lithium, aluminum, magnesium, salts thereof, cations thereof, and combinations thereof, and the metal is optionally aluminum, a salt thereof, or a cation thereof.

4. The coated substrate according to any one of claims 1 to 3, wherein the organic undercoat is polysiloxane or epoxy, and the epoxy is optionally an amine-cured epoxy.

5. The coated substrate according to any one of claims 1 to 4, wherein the surfactant is ethylene-oxide alcohol, propylene-oxide alcohol, or ethylene-oxide-propylene-oxide alcohol.

6. The coated substrate according to any one of claims 2 to 5, wherein the corrosion inhibitor is mercaptothiadiazole, and the dimercaptothiadiazole is optionally 2,5-dimercapto-1,3,4-thiadiazole.

7. The coated substrate according to any one of claims 1 to 6, wherein the sol-gel coating has a concentration of corrosion inhibitor of about 1 wt% to about 15 wt% based on the volume of the sol-gel coating.

8. The coated substrate according to any one of claims 1 to 7, wherein the organosilane is glycidoxypropyltrimethoxysilane, the acid is acetic acid, and the metal alkoxide is zirconium propoxide.

9. A method for preparing a coated substrate, Applying a sol-gel coating to a metal substrate to form a sol-gel coating, the sol-gel coating containing a corrosion inhibitor, applying the sol-gel coating; ​ Applying an undercoat agent coating over a sol-gel coating to form the undercoat agent coating, wherein the undercoat agent coating contains a metal, and applying the undercoat agent coating A method comprising.

10. The method according to claim 9, wherein applying the sol-gel coating comprises mixing a corrosion inhibitor with an organosilane and a metal alkoxide.

11. The method according to claim 9 or 10, wherein the volume ratio of the organosilane to the metal alkoxide is from about 5% to about 20%, the metal alkoxide is pretreated with an acid, and / or the volume ratio of the organosilane to the metal alkoxide is from about 9% to about 11%.

12. The metal of the undercoat agent coating is a plurality of metal particles independently selected from the group consisting of aluminum, lithium, magnesium, their salts, their cations, and combinations thereof, and the corrosion inhibitor after mixing optionally has a D90 particle size of from about 2 microns to about 5 microns. The method according to any one of claims 9 to 11.

13. The method according to any one of claims 9 to 12, further comprising pretreating the metal substrate before applying the sol-gel coating to the metal substrate.

14. Pretreating includes immersing the metal substrate in a solution maintained at a pH of 3.7 to 3.95 using 1N H ２ SO ４ or 1N NaOH, according to the method of claim 13.

15. The method according to claim 14, wherein the solution contains from about 3 grams to about 22 grams of a water-soluble trivalent chromium salt, from about 1.5 grams to about 11.5 grams of an alkali metal hexafluorozirconate, from about 0 grams to about 10 grams of a water-soluble thickener, and from about 0 grams to about 10 grams of a water-soluble surfactant selected from the group consisting of nonionic surfactants, anionic surfactants, cationic surfactants, and combinations thereof, per liter of the solution.

Images