Surface preparation of electrolytic inorganic veneers

Abstract

The title of the invention is surface preparation of electrolytic inorganic veneers. The present disclosure relates to substrate surface treatment methods and compositions. In at least one aspect, a method includes degreasing a metal substrate; carrying out first alkaline cleaning on the metal base material; etching the metal substrate by an electropolishing technique or with an alkaline etchant solution to form an etched metal substrate, wherein the etched metal substrate includes an average surface roughness (Ra) of about 8 [mu] in (2 [mu] m) to about 16 [mu] in (0.4 [mu] m); deoxidizing the etched metal substrate to form a processed metal substrate; carrying out alkaline cleaning on the processed metal base material; optionally, as desired, etch-cleaning and deoxidation are performed to remove the oxide, and a coating is deposited onto the processed metal substrate to form a coated metal substrate.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of and priority to U.S. Provisional Application Serial No. 63 / 526,368, filed on July 12, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0003] The present disclosure relates to methods and compositions for treating substrate surfaces. Background Art

[0004] Aircraft production requires efficient assembly processes to build large metal articles or structural components of such articles. In aircraft production, holes may be drilled separately in each component before the components are stacked and attached together, eliminating the conventional requirement associated with traditional assembly methods that the components must be stacked and aligned twice. However, while efficient assembly processes reduce production time and costs, large metal articles and structural components produced by such assembly processes are still susceptible to corrosion and environmental degradation throughout processing, assembly and use.

[0005] The application of inorganic finishes is often used to reduce and / or eliminate corrosion and environmental degradation that may result from the processing, assembly and use of such large metal articles and structural components. However, the processes and surface treatments (e.g., pickling) commonly used to apply such coatings may have undesirable effects on the surface of the substrate to which the coating is applied.

[0006] Therefore, there is a need to develop new substrate surface treatment methods and compositions for applying inorganic finishes to large metal objects and structural components.

[0007] References cited in the Information Disclosure Statement (37 CFR 1.97(h)) are: U.S. Patent Nos. 11,155,928; 11,303,047; 11,661,665; U.S. Application Nos. 16 / 721,081; 12 / 137,948. Summary of the invention

[0008] The present disclosure relates to methods and compositions for treating substrate surfaces.

[0009] In at least one aspect, a method comprises degreasing a metal substrate; subjecting the metal substrate to a first alkaline clean; etching the metal substrate with an alkaline etchant solution to form an etched metal substrate, wherein the etched metal substrate comprises an average surface roughness (R a); deoxidizing the etched metal substrate to form a processed metal substrate; subjecting the processed metal substrate to a second alkaline clean; and optionally performing additional etch cleaning and deoxidation to remove oxides and depositing a coating onto the processed metal substrate to form a coated metal substrate.

[0010] In at least one aspect, a method includes degreasing a metal substrate; subjecting the metal substrate to a first alkaline clean; etching the metal substrate with an alkaline etchant solution to form an etched metal substrate, the alkaline etchant solution comprising about 2 vol% to about 6 vol% triethanolamine, about 2 vol% to about 30 vol% sodium sulfide additive, about 10 vol% to about 40 vol% 50% sodium hydroxide, about 75 g / L or less dissolved metal content, and about 6 g / L or less ethylenediaminetetraacetic acid (EDTA); deoxidizing the etched metal substrate with a deoxidizing solution comprising about 40 vol% to about 60 vol% nitric acid to form a processed metal substrate, the deoxidizing solution being used alone or in combination with an iron-based or chromizing deoxidizing solution; The invention relates to a method for preparing an etched metal substrate and a method for preparing an etched metal substrate. The method comprises: subjecting the etched metal substrate to a second alkaline clean; optionally performing an additional etch clean with an alkaline etchant solution to form an etched metal substrate, wherein the alkaline etchant solution comprises about 2 vol% to about 6 vol% triethanolamine, about 2 vol% to about 30 vol% sodium sulfide additive, about 10 vol% to about 40 vol% 50% sodium hydroxide, about 75 g / L or less dissolved metal content, and about 6 g / L or less ethylenediaminetetraacetic acid (EDTA); deoxidizing the etched metal substrate with a deoxidizing solution comprising about 40 vol% to about 60 vol% nitric acid to form a processed metal substrate, the deoxidizing solution being used alone or in combination with an iron-based or chromizing deoxidizing solution, and depositing a coating on the deoxidized metal substrate to form a coated metal substrate.

[0011] In at least one aspect, a method includes degreasing a metal substrate; subjecting the metal substrate to a first alkaline clean; etching the metal substrate with an alkaline etchant solution to form an etched metal substrate, the alkaline etchant solution comprising about 2 vol% to about 6 vol% triethanolamine, about 2 vol% to about 30 vol% sodium sulfide additive, about 10 vol% to about 40 vol% 50% sodium hydroxide, about 75 g / L or less dissolved metal content, and about 6 g / L or less ethylenediaminetetraacetic acid (EDTA); deoxidizing the etched metal substrate with a deoxidizing solution to form a processed metal substrate, the deoxidizing solution comprising about 40 vol% to about 60 vol% nitric acid; subjecting the processed metal substrate to a second alkaline clean; and optionally subjecting the processed metal substrate to an alkaline etchant solution. The invention relates to a method for preparing a metal substrate for etching and deoxidizing the etched metal substrate, wherein the deoxidizing solution comprises about 40 vol% to 60 vol% nitric acid, and if necessary, the deoxidizing solution is used alone or in combination with an iron-based or chromized deoxidizer to remove oxides, and depositing a coating on the processed metal substrate to form a coated metal substrate, wherein depositing the coating on the processed metal substrate comprises electrolytically depositing an inorganic finish thereon, and the electrolytic deposition of the inorganic finish comprises attaching the processed metal substrate to two or more counter electrodes, electrically connecting the processed metal substrate to a power source, immersing the processed metal substrate in an inorganic finishing solution, applying a current density to the processed metal substrate to form a coated metal substrate, and rinsing the coated metal substrate.

[0012] In at least one aspect, the coated metal substrate comprises an etched metal substrate, the etched metal substrate comprising a metal substrate having an average surface roughness of about 79 μin (2 μm) to about 8 μin (0.2 μm), wherein the average surface roughness of the metal substrate is the result of etching the metal substrate in an etching solution and deoxidizing the metal substrate in a deoxidizing solution comprising about 40 vol% to about 60 vol% nitric acid; and an inorganic finish disposed on the etched metal substrate, wherein the inorganic finish comprises substantially Figure 2 The form shown in . BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to be able to understand the above-mentioned features of the present disclosure in detail, a more specific description of the present disclosure briefly summarized above may be made with reference to various aspects, some of which are shown in the accompanying drawings. However, it should be noted that the accompanying drawings illustrate only typical aspects of the present disclosure and are therefore not to be considered as limiting the scope thereof, as the present disclosure may admit to other equally effective aspects.

[0014] Figure 1 yes Figure 1 A schematic cross-sectional view of a structural assembly before being fastened with a fastening system.

[0015] Figure 2 A representative example of an aluminum substrate that has been chemically etched with an alkaline etchant composition and deoxidized with a deoxidizing solution having 50 vol% HNO3 is shown.

[0016] Figure 3 A representative example of an aluminum substrate that has been chemically etched with a pickling composition and deoxidized with a deoxidizing solution having a chromating deoxidizing component is shown.

[0017] Figure 4 A 7075-T6 aluminum metal substrate, which had been chemically etched with an alkaline etchant composition, deoxidized with a deoxidizing solution having 50 vol% HNO3, and electrolytically coated with an inorganic finish, is shown after 336 hours in a neutral salt spray environment.

[0018] Figure 5 A 2024-T3 aluminum metal substrate, which had been chemically etched with an alkaline etchant composition, deoxidized with a deoxidizing solution having 50 vol% HNO3, and electrolytically coated with an inorganic finish, is shown after 336 hours in a neutral salt spray environment. DETAILED DESCRIPTION

[0019] Includes pre-forming (e.g., pre-drilling) holes in different structural elements (also referred to herein as substrate(s)) separately (e.g., at remote geographic locations, at different times, at different locations within the same geographic area, etc.), and then once the holes are formed, bringing the structural elements together and assembling (e.g., aligning, stacking, and fastening) them to form a structural assembly.

[0020] like Figure 1 Schematically shown in , the device includes a structural assembly 12 and a fastening system. The structural assembly 12 includes at least two structural elements (e.g., a first structural element 16 and a second structural element 18), and the at least two structural elements are fastened to each other via the fastening system. In one or more aspects, the structural assembly 12 can be connected together to form one or more parts of an aircraft, a spacecraft, a land vehicle, an engine, a propulsion structure, a space re-entry vehicle and / or its structure, a power generation turbine or a combination thereof. In some aspects, the structural assembly 12 can be an accessory and / or a joint, such as one or more of a fuel tank joint, a wing joint, a fuselage joint, a fuselage side joint, and a main accessory.

[0021] exist Figure 1In the example of the present invention, the at least two structural elements include two structural elements, namely the first structural element 16 and the second structural element 18. However, in other examples, the structural assembly 12 includes more than two structural elements, such as three, four, five, six, seven or eight, or more structural components fastened together by a fastening system. In addition, the first structural element 16 further includes a first structural element side wall 22 and a first structural element hole side wall 35. The second structural element 18 further includes a second structural element side wall 41 and a second structural element hole side wall 37. In some such examples, more than two components are preformed, stacked and assembled, and then fastened to each other.

[0022] At least a portion of the second structural element 18 is positioned adjacent to the first structural element 16 so that at least a portion of the first structural element 18 and the second structural element 18 directly physically touch each other. Due to their proximity, the first structural element 16 and the second structural element 18 in some examples include components of the same aircraft part (for example, both structural elements can be components of a fuel tank). However, in other examples, the first structural element 16 and the second structural element 18 include components of different but adjacent aircraft parts (for example, a wing and a fuel tank, a wing and an engine, a wing and a fuselage, etc.), and in some such examples, the first structural element 16 and the second structural element 18 are fastened to each other to couple different aircraft parts. The first structural element 16 and the second structural element 18 together form the structural assembly 12.

[0023] In some aircraft assembly processes, holes are pre-formed (e.g., pre-drilled, pre-formed, pre-reamed, or otherwise pre-formed) in the first structural element 16 and the second structural element 18 prior to assembling the structural elements into the structural assembly 12. Specifically, the first structural element hole 48 is drilled, formed, reamed, or otherwise formed in the first structural element 16, and the second structural element hole 50 is drilled, formed, reamed, or otherwise formed in the second structural element 18. Although Figure 1 1 and 18, but in other examples, the first structural element 16 and the second structural element 18 include a plurality of first structural element holes 48 and second structural element holes 50. In some such examples, the number of first structural element holes 48 and second structural element holes 50 included in the first structural element 16 and the second structural element 18 depends on the size and shape of the structural assembly 12 and the desired level of fastening for a particular application.

[0024] Before assembly, it may be desirable to deposit a coating on one or more structural elements of the structural assembly. One of ordinary skill in the art will appreciate that the method for coating a substrate may include a variety of methods and processes, depending on the substrate to be coated, the composition of the coating and the coating deposition method implemented. In some aspects, the method for depositing the coating on the one or more structural elements includes one or more substrate cleaning processes, one or more substrate surface preparation processes, and one or more coating deposition processes. The shape and structure of the substrate can be arbitrarily selected according to the parameters related to the assembly process, and is not limited to a planar surface. For example, the substrate can have a non-planar shape and have a surface to which a coating can be applied. In one or more aspects, the substrate is a metal substrate selected from aluminum, an aluminum alloy, or a mixture thereof.

[0025] In one or more aspects, the metal substrate is subjected to a cleaning step, including degreasing the substrate. The metal substrate can be degreased using any of the following degreasing agents: for example, acetone or an aqueous alkaline degreasing agent. This step may include immersing the metal substrate in the degreasing agent for about 5 min to about 30 min, manually cleaning with a cloth, and applying ultrasonic agitation for about 5 min to about 20 min, or until there is neither oil nor grease residue on its surface. In addition, after the degreasing step, hot air can also be used to dry the metal substrate. In some embodiments, solvent vapor degreasing, vacuum cycle nucleation (vacuum cycle nucleation, VCN) and combinations thereof can be used to clean the metal substrate.

[0026] In one or more aspects, the metal substrate is subjected to an alkaline cleaning step to form a cleaned metal substrate. The alkaline cleaning can be performed by immersing the metal substrate in an aqueous alkaline cleaner such as, for example, 38 to 60 g / L of Bonderite C-AK 4215NC LT Aero and 0 to 0.25 volume % of Bonderite C-AD 4215Aero for a time range of about 5 min to about 30 min. In at least one aspect, the alkaline cleaning is performed at a temperature of about 40° C. to about 60° C.

[0027] The cleaned metal substrate may be etched via one or more etching methods known to those of ordinary skill in the art, such as chemical etching, pickling, physical abrasion, mechanical polishing, machining, electropolishing, or a combination thereof.

[0028] In some aspects, the cleaned metal substrate is chemically etched using an alkaline etchant solution to form an etched metal substrate. In at least one aspect, the alkaline etchant solution comprises about 2 vol% to about 6 vol% of triethanolamine, such as about 2 vol% to about 4 vol%. In at least one aspect, the alkaline etchant solution comprises about 2 vol% to about 30 vol% of a sodium sulfide additive, such as about 10 vol% to about 20 vol%. In at least one aspect, the alkaline etchant solution comprises about 10 vol% to about 40 vol% of a 50% sodium hydroxide additive, such as about 15 vol% to about 20 vol%. In at least one aspect, the alkaline etchant solution comprises about 0 g / L to about 75 g / L of dissolved metal content, such as about 75 g / L or less. In at least one aspect, the alkaline etchant solution comprises about 6 g / L or less of ethylenediaminetetraacetic acid (EDTA).

[0029] In one or more aspects, chemical etching of the cleaned metal substrate is performed by immersing the cleaned metal substrate in an alkaline etchant solution for about 1 min to about 10 min (e.g., about 2 min to about 7 min). In some aspects, chemical etching of the cleaned metal substrate comprises heating the cleaned metal substrate, the alkaline etchant solution, or both to a temperature of about 30° C. to about 55° C. (e.g., about 35° C. to about 50° C.).

[0030] In some aspects, the cleaned metal substrate is physically abraded and / or mechanically polished to form an etched metal substrate. In one or more aspects, the physical abrasion process may include dry blasting the metal substrate with one or more of aluminum oxide grit, silicon carbide grit, glass beads, steel grit, and combinations thereof. In one or more optional aspects, the metal substrate may be mechanically and / or manually polished with emery paper, and powder remaining on the surface of the metal substrate may be removed via any suitable method.

[0031] In some aspects, the cleaned metal substrate is etched via immersion in a nitric acid / HF solution in accordance with PS12050.1 Sec. 3.3.1, which is incorporated herein by reference.

[0032] In one or more aspects, the cleaned metal substrate surface is etched to a desired surface roughness via any one or more electropolishing methods known to one of ordinary skill in the art.

[0033] In one or more aspects, the etched metal substrate is subjected to a deoxidation process to form a processed metal substrate. The deoxidation process can be implemented by immersing the aluminum substrate in a deoxidation bath containing nitric acid (HNO3) (e.g., in the range of 35% to 50% by volume) during a period of 1 to 5 minutes, and / or immersing the aluminum substrate in a deoxidizer (such as, for example, 18% to 20% by volume of a non-chromium deoxidizer Bonderite C-IC SmutGo NC Aero) during a period of 1 to 10 minutes. In some aspects, the etched metal substrate is deoxidized by immersing in a deoxidation bath for about 4 minutes to about 12 minutes, and the deoxidation bath includes a non-chromium deoxidizer Bonderite C-IC SmutGo AERO ACID. For example, the deoxidation process can be implemented at a temperature in the range of about 20°C to about 50°C. Thereafter, the aluminum substrate can be rinsed, for example, with tap water and then with deionized water. In some aspects, deoxidizing the etched metal substrate comprises immersing the etched metal substrate in a deoxidizing solution consisting of about 40 vol% to about 60 vol% (e.g., about 50 vol%) nitric acid. The etched metal substrate is immersed in the deoxidizing solution for about 1 min to about 10 min (e.g., about 7 min).

[0034] In some aspects, the processed metal substrate is subjected to alkaline cleaning. The alkaline cleaning can be performed by immersing the processed metal substrate in an aqueous alkaline cleaning agent such as the following during a period ranging from about 5 min to about 30 min (such as about 10 min to 20 min): for example, Bonderite C-AK 4215NC LT Aero in the range of 38 to 60 g / L and Bonderite C-AD 4215Aero in the range of 0 to 0.25 volume %. In at least one aspect, the alkaline cleaning is performed at a temperature of about 35°C to about 65°C (such as about 40°C to about 60°C, such as about 45°C to about 55°C, such as about 47°C to about 52°C), wherein the metal substrate, the aqueous alkaline cleaning agent, or both are heated. In some aspects, the pH of the alkaline cleaning solution is about 10 to about 12.

[0035] In some aspects, the surface roughness component of the machined metal substrate texture (defined in accordance with ASME B46.1) has an average surface roughness (R a): about 500 μin (13 μm) or less, such as about 400 μin (10 μm) or less, such as about 300 μin (7.6 μm) or less, such as about 250 μin (6.4 μm) or less, such as about 200 μin (5.1 μm) or less, such as about 150 μin (3.8 μm) or less, such as about 100 μin (2.5 μm) or less, such as about 50 μin (1.3 μm) or less, such as about 25 μin (0.6 μm) or less, such as about 10 μin (0.3 μm) or less, such as about 5 μin (0.13 μm) or less, such as about 2.5 μin (0.1 μm) or less, such as about 1 μin (0.03 μm) or less. In one or more optional embodiments, the processed metal substrate has the following R a : about 250 μin (6.4 μm) to about 0.001 μin (0.025 nm), such as about 200 μin (5.1 μm) to about 0.005 μin (0.13 nm), such as about 100 μin (2.5 μm) to about 0.01 μin (0.25 nm), such as about 50 μin (1.3 μm) to about 0.025 μin (0.64 nm), such as about 25 μin (0. 6μm) to about 0.05μin (1.3nm), such as about 10μin (0.3μm) to about 0.075μin (1.9nm), such as about 5μin (0.13μm) to about 0.1μin (2.5nm), such as about 2.5μin (0.1μm) to about 0.15μin (3.8nm), such as about 2μin (0.05μm) to about 0.2μin (0.01μm).

[0036] In some aspects, the processed metal substrate has a t =R v +R p The sum of the highest peak and the lowest valley determined (R t ), where R v is measured from R a The absolute value of the maximum valley depth, and R p is measured from R a In some aspects, the processed metal substrate has the following R t : about 550 μin (14 μm) to about 710 μin (18 μm), such as about 590 μin (15 μm) to about 670 μin (17 μm). In one or more optional aspects, the processed metal substrate has the following R t : about 197μin (5μm) to about 394μin (10μm), optionally about 158μin (4μm) to about 236μin (6μm), optionally about 236μin (6μm) to about 315μin (8μm).

[0037] In some aspects, the coating is deposited onto a processed metal substrate. The processed metal substrate is attached to a support made of a suitable conductive material and immersed in a coating solution. In at least one aspect, the coating solution is an inorganic finishing solution. In addition, a busbar made of a suitable conductive material is suspended above the inorganic finishing solution. Two or more counter electrodes are attached to the busbar so that the electrodes are immersed in the solution, no more than 1 foot from the working surface. The depth of the counter electrode immersion is shallower than the part in order to avoid high current density areas on the part. In addition, the busbar is also electrically connected to a rectifier to give the desired polarity to the counter electrode of the cathode or anode.

[0038] In addition, the support to which the processed metal substrate is attached is electrically connected to the rectifier so that the polarity of the support and the counter electrode are opposite. The rectifier is then powered on during the entire duration of the inorganic finishing process. When the inorganic finishing deposition ends, the rectifier is powered off, and the support is disconnected from the rectifier and removed from the inorganic finishing solution. Then, the coated metal substrate is removed from the support, rinsed with water and / or any suitable solvent, and dried by any suitable method known to those of ordinary skill in the art. Optionally, the support and busbar can be electrically connected to the rectifier, and the rectifier is powered on before the support is immersed in the inorganic finishing solution. In some embodiments, the support can be removed at the end of the inorganic finishing process while the rectifier is still working.

[0039] In some aspects, the processed metal substrate is immersed in an inorganic finishing solution and a current density is provided to deposit the coating onto the processed metal substrate. In one or more aspects, the processed metal substrate is immersed in a MIL-DTL-81706 Type II conversion coating solution, wherein the conversion coating solution is an inorganic finishing solution. In some aspects, the current density supplied to the processed metal substrate during the coating deposition is provided by an appropriate DC power in a constant current mode, a pulsed current mode, or a combination thereof to provide a cathodic or anodic current density.

[0040] In one or more aspects, the current density supplied to the processed metal substrate is a constant current having a current density of about 0.2 mA / cm 2 to about 0.5 mA / cm 2 (e.g. about 0.25 mA / cm 2 to about 0.45 mA / cm 2 In at least one aspect, a constant current is applied to the processed metal substrate for a duration of about 2 min to about 5 min (eg, about 2.5 min to about 4 min).

[0041] In one or more embodiments, the current density is supplied by using a constant voltage to the processed metal substrate until the desired potential threshold is reached to fully deposit the coating on the substrate. In one or more embodiments, the voltage applied to the metal substrate is from about 0.5V to about 10V, such as from about 1.0V to about 8V, such as from about 1.5V to about 6V, such as from about V to about 2V, such as from about 4V to about 3V. In at least one aspect, the voltage is applied to the processed metal substrate for about 30 seconds to about 10min, such as from about 1min to about 8min, such as from about 2min to about 6min, such as from about 2min to about 4min, such as from about 2min to about 3min.

[0042] After the coating deposition process is completed, the coated metal substrate is removed, rinsed, and dried via any one or more suitable methods known to those of ordinary skill in the art.

[0043] In some aspects, the film mass of the coating on the coated metal substrate is about 0.05 mg / cm 2 To about 0.11mg / cm 2 , such as about 0.07 mg / cm 2 To about 0.09mg / cm 2 .

[0044] The coating deposited onto the coated metal substrate provides corrosion protection. The coating applied to the processed metal substrate in accordance with ASTM B117 provides corrosion protection for a minimum of 336 hours in a salt spray environment without forming pits greater than 0.031 in. in diameter and without forming pits greater than 30 in. in diameter. 2 More than 5 pits are formed in the area, and / or not within 150in 2 In one or more aspects, the coating deposited onto the coated metal substrate provides this corrosion protection for a minimum of about 336 hours, such as about 500 hours to about 800 hours.

[0045] Other aspects

[0046] In addition, the present disclosure also provides the following aspects, each of which can be regarded as optionally including any alternative aspects.

[0047] Clause 1. A method comprising:

[0048] Degrease the metal substrate;

[0049] performing a first alkaline cleaning on the metal substrate;

[0050] The metal substrate is etched with an alkaline etchant solution to form an etched metal substrate, wherein the etched metal substrate comprises an average surface roughness (R a);

[0051] deoxidizing the etched metal substrate to form a processed metal substrate;

[0052] optionally subjecting the processed metal substrate to a second alkaline cleaning; and

[0053] A coating is deposited onto the processed metal substrate to form a coated metal substrate.

[0054] Clause 2. The method of clause 1, wherein the alkaline etchant solution comprises about 2 vol% to about 6 vol% triethanolamine, about 2 vol% to about 30 vol% sodium sulfide additive, about 10 vol% to about 40 vol% 50% sodium hydroxide, about 75 g / L or less dissolved metal content, and about 6 g / L or less ethylenediaminetetraacetic acid (EDTA).

[0055] Clause 3. The method of clause 1 or 2, wherein the processed metal substrate comprises an average surface roughness R of about 8 μin (0.2 μm) to about 79 μin (2 μm). a .

[0056] Item 4. The method of any one of Items 1 to 3, wherein the sum of the highest peak and the lowest valley of the surface of the processed metal substrate (R t ) is about 158μin (4μm) to about 236μin (6μm).

[0057] Clause 5. The method of any one of Clauses 1 to 4, wherein deoxidizing the etched metal substrate comprises immersing the etched metal substrate in a deoxidizing solution comprising about 40 vol % to about 60 vol % nitric acid.

[0058] Clause 6. The method of any one of clauses 1 to 5, wherein depositing the coating onto the processed metal substrate comprises electrolytically depositing an inorganic finish thereon, the electrolytic deposition of the inorganic finish comprising:

[0059] attaching the processed metal substrate to a counter electrode,

[0060] electrically connecting the processed metal substrate to a power source,

[0061] The processed metal substrate is immersed in an inorganic coating solution,

[0062] applying a current density to the processed metal substrate to form a coated metal substrate,

[0063] removing the coated metal substrate from the inorganic finishing solution, and

[0064] The coated metal substrate is rinsed.

[0065] Clause 7. The method of any of Clauses 1 to 6, wherein the current density is applied to the processed metal substrate for about 2 minutes to about 5 minutes.

[0066] Clause 8. The method of any one of clauses 1 to 7, wherein the coating applied to the metal substrate provides a minimum of 336 hours of corrosion protection in a salt spray environment without pits having a diameter of about 0.031 in or less; 2 There are less than 5 pits in the area and within 150in 2 There are fewer than 15 pits in the area.

[0067] Clause 9. The method of any one of clauses 1 to 8, wherein the coating applied to the metal substrate provides a minimum of 336 hours of corrosion protection in a salt spray environment without pits having a diameter of about 0.031 in or less; 2 Less than 5 pits within 150in 2 There are fewer than 15 pits in the area.

[0068] Clause 10. A method comprising:

[0069] Degrease the metal substrate;

[0070] performing a first alkaline cleaning on the metal substrate;

[0071] etching the metal substrate with an alkaline etchant solution to form an etched metal substrate, the alkaline etchant solution comprising about 2 vol% to about 6 vol% triethanolamine, about 2 vol% to about 30 vol% sodium sulfide additive, about 10 vol% to about 40 vol% 50% sodium hydroxide, about 75 g / L or less dissolved metal content, and about 6 g / L or less ethylenediaminetetraacetic acid (EDTA);

[0072] deoxidizing the etched metal substrate with a deoxidizing solution comprising about 40 vol% to about 60 vol% nitric acid, the deoxidizing solution being used alone or in combination with an iron-based or chromizing deoxidizing solution to form a processed metal substrate;

[0073] performing a second alkaline cleaning on the processed metal substrate; optionally performing etching cleaning with the alkaline etchant;

[0074] deoxidizing the etched metal substrate with a deoxidizing solution comprising about 40 vol% to about 60 vol% nitric acid to form a processed metal substrate, the deoxidizing solution being used alone or in combination with an iron-based or chromizing deoxidizing solution to remove oxides, if desired, and

[0075] The coating is deposited onto the deoxidized metal substrate to form a coated metal substrate.

[0076] Clause 11. The method of clause 10, wherein depositing the coating onto the processed metal substrate comprises electrolytically depositing an inorganic finish thereon, the electrolytic deposition of the inorganic finish comprising:

[0077] Attaching the processed metal substrate to a counter electrode, (cathode),

[0078] electrically connecting the processed metal substrate to a power source,

[0079] The processed metal substrate is immersed in an inorganic coating solution,

[0080] applying a current density to the processed metal substrate to form a coated metal substrate,

[0081] removing the coated metal substrate from the inorganic finishing solution, and

[0082] The coated metal substrate is rinsed.

[0083] Clause 12. The method of clause 10 or 11, wherein the processed metal substrate comprises an R of about 8 μin (0.2 μm) to about 79 μin (2 μm). a .

[0084] Clause 13. The method of any one of clauses 10 to 12, wherein the surface R of the processed metal substrate t It is about 158μin (4μm) to about 236μin (6μm).

[0085] Clause 14. The method of any of Clauses 10 to 13, wherein the current density is applied to the processed metal substrate for about 2 minutes to about 5 minutes.

[0086] Clause 15. The method of any of clauses 10 to 14, wherein the coating applied to the metal substrate provides corrosion protection for a minimum of 336 hours in a salt spray environment without pits of about 0.031 in. in diameter or less and at a depth of 30 in. 2 Less than 5 pits within 150in 2 There are fewer than 15 pits in the area.

[0087] Clause 16. A method comprising:

[0088] Degrease the metal substrate;

[0089] performing a first alkaline cleaning on the metal substrate;

[0090] etching the metal substrate with an alkaline etchant solution to form an etched metal substrate, the alkaline etchant solution comprising about 2 vol% to about 6 vol% triethanolamine, about 2 vol% to about 30 vol% sodium sulfide additive, about 10 vol% to about 40 vol% (e.g., 50% sodium hydroxide), about 75 g / L or less dissolved metal content, and about 6 g / L or less ethylenediaminetetraacetic acid (EDTA);

[0091] deoxidizing the etched metal substrate with a deoxidizing solution to form a processed metal substrate, the deoxidizing solution comprising about 40 vol % to about 60 vol % nitric acid;

[0092] performing a second alkaline cleaning on the processed metal substrate; optionally performing alkaline etching cleaning with the alkaline etchant and deoxidizing the etched metal substrate with a deoxidation solution comprising about 40 vol % to about 60 vol % nitric acid, the deoxidation solution being used alone or in combination with an iron-based or chromating deoxidation solution to remove oxides, if desired,

[0093] Depositing a coating onto the processed metal substrate to form a coated metal substrate, wherein depositing the coating onto the processed metal substrate comprises electrolytically depositing an inorganic finish thereon, the electrolytic deposition of the inorganic finish comprising:

[0094] attaching the processed metal substrate to two or more counter electrodes,

[0095] electrically connecting the processed metal substrate to a power source,

[0096] The processed metal substrate is immersed in an inorganic coating solution,

[0097] applying a current density to the processed metal substrate to form a coated metal substrate, and

[0098] The coated metal substrate is rinsed.

[0099] Clause 17. The method of clause 16, wherein the current density applied to the processed metal substrate is about 0.2 mA / cm 2 to about 0.5 mA / cm 2 .

[0100] Clause 18. The method of Clause 16 or 17, wherein the current density is applied to the processed metal substrate for about 2 minutes to about 5 minutes.

[0101] Clause 19. The method of Clause 16 or 18, wherein the current density applied to the processed metal substrate is a constant current.

[0102] Clause 20. A method comprising:

[0103] Degrease the metal substrate;

[0104] performing a first alkaline cleaning on the metal substrate;

[0105] The metal substrate is etched by an electropolishing technique or with an alkaline etchant solution to ensure 5 μm to 13 μm of material removal, thereby forming an etched metal substrate, wherein the etched metal substrate comprises an average surface roughness (R) of about 2 μin (0.05 μm) to about 20 μin (0.5 μm). a );

[0106] deoxidizing the etched metal substrate to form a processed metal substrate;

[0107] optionally subjecting the processed metal substrate to a second alkaline cleaning; and

[0108] A coating is deposited onto the processed metal substrate to form a coated metal substrate.

[0109] Clause 21. A coated metal substrate comprising:

[0110] An etched metal substrate, the etched metal substrate comprising a metal substrate having an average surface roughness of about 79 μin (2 μm) to about 8 μin (0.2 μm), wherein:

[0111] The average surface roughness of the metal substrate is a result of etching the metal substrate in an etching solution and deoxidizing the metal substrate in a deoxidizing solution comprising about 40 vol % to about 60 vol % nitric acid, and

[0112] An inorganic finish disposed on the etched metal substrate, wherein the conversion coating comprises substantially Figure 2 The form in .

[0113] Example

[0114] Sample preparation

[0115] 7050-T7451, 7075-T6 and 2024-T3 aluminum samples were machined into desired sizes and shapes, degreased and cleaned with acetone, and subjected to alkaline cleaning to produce clean aluminum substrates. The clean aluminum substrates were chemically etched with an alkaline etchant composition comprising triethanolamine, sodium sulfide additive, sodium hydroxide, metal content and ethylenediaminetetraacid. The etched aluminum substrates were then subjected to a deoxidation process in which each sample was immersed in a deoxidation composition having approximately 50 vol% HNO3. It is important to note that the use of a deoxidation composition having approximately 50 vol% HNO3 will not etch the aluminum substrate, but will attack intermetallics.

[0116] For comparison purposes, additional cleaned aluminum substrates were chemically etched using the pickling composition and process in accordance with PS 12050.1.Each etched metal sample was then subjected to a deoxidation process wherein the deoxidation solution contained a chromating deoxidation component.

[0117] Surface analysis

[0118] Deoxidized aluminum substrates were observed using a stylus (surface contact) profilometer and white light interferometer to analyze the surface characteristics of the substrate before and after etching and deoxidation of the substrate. The former surface roughness characterization method involves a stylus of defined diameter that is contacted and dragged a distance of 0.25mm to 0.8mm with the substrate surface and is performed with instruments such as the Mitutoyo Surftest, while the latter method is non-contact surface topography that relies on the interference of light waves from a light source with light reflected from the substrate to infer surface roughness and is performed with instruments such as the Bruker Contour GT-K 3D optical microscope. Figure 2 A representative example of an aluminum substrate that has been chemically etched with an alkaline etchant composition and deoxidized with a deoxidizing solution having 50 vol% HNO3 is shown. Figure 3 A representative example of an aluminum substrate that has been chemically etched with a pickling composition and deoxidized with a deoxidizing solution having a chromating deoxidizing component is shown.

[0119] Electrolytic coating

[0120] The deoxidized aluminum substrate was coated using an electrolytic coating process in which the deoxidized aluminum substrate was placed on a titanium alloy support and immersed in SurTec 650 inorganic finishing solution. An appropriate DC power supply was connected to the titanium alloy support and two 1000 series aluminum counter electrodes. The power supply was then operated to supply a constant voltage to provide no more than 1.0 mA / cm 2 The duration of coating formation is equal to or less than 10 minutes, at which time the power is turned off and the coated aluminum substrate is removed from the inorganic finishing solution. The coated aluminum substrate is then rinsed and dried.

[0121] Salt spray test

[0122] The coating performance is evaluated according to the neutral salt spray test outlined in ASTM B117. If no pits larger than 0.031 in. in diameter are formed in a neutral salt spray environment for a minimum of 336 hours, the ... 2 No more than 5 pits are formed in the area, and within 150in 2The coating applied to the aluminum metal substrate is determined to be a MIL-A-8625 pass rating if no more than 15 pits are formed in the area. Here, pits are defined as visible black spots or pits, showing white corrosion products around the pits, or in the form of tails. Figure 4 and Figure 5 7075-T6 and 2024-T3 aluminum metal substrates, which had been chemically etched with an alkaline etchant composition, deoxidized with a deoxidizing solution having 50 vol% HNO3, and electrolytically coated with an inorganic finish, are shown after 336 hours in a neutral salt spray environment.

[0123] Unless otherwise specified, the phrase "consisting essentially of..." does not exclude the presence or absence of other steps, elements or materials specifically mentioned in the specification, as long as these steps, elements or materials do not affect the basic and novel characteristics of the present disclosure. In addition, they do not exclude impurities and changes normally associated with the elements and materials used.

[0124] As used herein, numerical ranges include the numbers recited within the range. For example, a numerical range of "1 wt % to 10 wt %" includes 1 wt % and 10 wt % within the recited range.

[0125] For the sake of brevity, only certain ranges are explicitly disclosed herein. However, the range from any lower limit can be combined with any upper limit to describe the range that is not explicitly described, and the range from any lower limit can be combined with any other lower limit to describe the range that is not explicitly described, and similarly, the range from any upper limit can be combined with any other upper limit to describe the range that is not explicitly described. In addition, each point or single value between its endpoints is included in the range, even if it is not explicitly described. Therefore, each point or single value can serve as its own lower limit or upper limit - combined with any other point or single value or any other lower limit or upper limit, to describe the range that is not explicitly described.

[0126] All numerical values ​​in the detailed description herein are modified by the "about" indication, and take into account experimental error and variations that would be expected by one of ordinary skill in the art.

[0127] All documents described herein are incorporated herein by reference, including any priority documents and / or test procedures to the extent that they are not inconsistent with this text. It is apparent from the foregoing general description and specific aspects that, although the forms of the present disclosure are exemplified and described, various modifications can be made without departing from the spirit and scope of the present disclosure. Therefore, the present disclosure is not intended to be limited thereby. Similarly, with respect to U.S. law, the term "comprising" is considered to be synonymous with the term "including". Similarly, whenever there is a transition phrase "comprising" in front of a composition, an element, or a group of elements, it should be understood that we also consider the same composition or group of elements with the transition phrases "mainly consisting of...", "consisting of...", "selected from..." or "is" in front of the narration of the composition, element, or multiple elements, and vice versa.

[0128] While various aspects and examples of the disclosure have been described, those skilled in the art, having benefit of this disclosure, will appreciate that other aspects can be devised which do not depart from the scope and spirit of the disclosure.

Claims

1. A method comprising: Degrease the metal substrate; performing a first alkaline cleaning on the metal substrate; The metal substrate is etched with an alkaline etchant solution to form an etched metal substrate (22 or 41), wherein the etched metal substrate (22 or 41) comprises an average surface roughness (R) of about 250 μin (6.4 μm) or less. a ); deoxidizing the etched metal substrate (22 or 41) to form a processed metal substrate; optionally subjecting the processed metal substrate to a second alkaline cleaning; as well as A coating (35 or 37) is deposited onto the processed metal substrate to form a coated metal substrate (16 or 18).

2. The method of claim 1 , wherein the alkaline etchant solution comprises about 2 vol % to about 6 vol % triethanolamine, about 2 vol % to about 30 vol % sodium sulfide additive, about 10 vol % to about 40 vol % 50% sodium hydroxide, about 75 g / L or less dissolved metal content, and about 6 g / L or less ethylenediaminetetraacetic acid (EDTA).

3. The method of claim 1, wherein the processed metal substrate comprises an average surface roughness R of about 8 μin (0.2 μm) to about 16 μin (0.4 μm). a .

4. The method according to claim 1, wherein the sum of the highest peak and the lowest valley on the surface of the processed metal substrate (R t ) is about 158μin (4μm) to about 236μin (6μm).

5. The method of claim 1, wherein deoxidizing the etched metal substrate (22 or 41) comprises immersing the etched metal substrate (22 or 41) in a deoxidizing solution comprising about 40 vol% to about 60 vol% nitric acid.

6. The method of claim 1, wherein depositing the coating (35 or 37) onto the processed metal substrate comprises electrolytically depositing an inorganic finish thereon, the electrolytic deposition of the inorganic finish comprising: attaching the processed metal substrate to a counter electrode, electrically connecting the processed metal substrate to a power source, The processed metal substrate is immersed in an inorganic coating solution, applying a current density to the processed metal substrate to form a coated metal substrate (16 or 18), removing the coated metal substrate (16 or 18) from the inorganic finishing solution, and The coated metal substrate (16 or 18) is rinsed.

7. The method of claim 6, wherein the current density is applied to the processed metal substrate for about 2 minutes to about 5 minutes.

8. The method of claim 1, wherein the coating (35 or 37) applied to the metal substrate provides a minimum of 336 hours of corrosion protection in a salt spray environment without pits of about 0.031 in. in diameter or less; 2 Less than 5 pits within 150in 2 There are fewer than 15 pits in the area.

9. The method of claim 6, wherein the coating (35 or 37) applied to the metal substrate provides a minimum of 336 hours of corrosion protection in a salt spray environment without pits of about 0.031 in. in diameter or less; 2 Less than 5 pits within 150in 2 There are fewer than 15 pits in the area.

10. A method comprising: Degrease the metal substrate; performing a first alkaline cleaning on the metal substrate; etching the metal substrate with an alkaline etchant solution to form an etched metal substrate (22 or 41), the alkaline etchant solution comprising about 2 vol% to about 6 vol% triethanolamine, about 2 vol% to about 30 vol% sodium sulfide additive, about 10 vol% to about 40 vol% 50% sodium hydroxide, about 75 g / L or less dissolved metal content, and about 6 g / L or less ethylenediaminetetraacetic acid (EDTA); deoxidizing the etched metal substrate (22 or 41) with a deoxidizing solution comprising about 40 vol% to about 60 vol% nitric acid to form a processed metal substrate; performing a second alkaline cleaning on the processed metal substrate; optionally performing alkaline etching cleaning and deoxidizing the etched metal substrate with the alkaline etchant, the deoxidation solution comprising about 40 vol% to about 60 vol% nitric acid, and if necessary, the deoxidation solution can be used alone or in combination with an iron-based or chromium-based deoxidation solution to remove oxides; A coating (35 or 37) is deposited onto the deoxidized metal substrate to form a coated metal substrate (16 or 18).

11. The method of claim 10, wherein depositing a coating (35 or 37) onto the processed metal substrate comprises electrolytically depositing an inorganic finish thereon, the electrolytic deposition of the inorganic finish comprising: attaching the processed metal substrate to a counter electrode, electrically connecting the processed metal substrate to a power source, The processed metal substrate is immersed in an inorganic coating solution, applying a current density to the processed metal substrate to form a coated metal substrate (16 or 18), removing the coated metal substrate (16 or 18) from the inorganic finishing solution, and The coated metal substrate (16 or 18) is rinsed.

12. The method of claim 10, wherein the processed metal substrate comprises an R a .

13. The method according to claim 10, wherein the surface R of the processed metal substrate t It is about 158μin (4μm) to about 236μin (6μm).

14. The method of claim 11, wherein the current density is applied to the processed metal substrate for about 2 minutes to about 5 minutes.

15. The method of claim 11, wherein the coating (35 or 37) applied to the metal substrate provides a minimum of 336 hours of corrosion protection in a salt spray environment without pits of about 0.031 in. in diameter or less and ... 2 Less than 5 pits within 150in 2 There are fewer than 15 pits in the area.

16. A method comprising: Degrease the metal substrate; performing a first alkaline cleaning on the metal substrate; etching the metal substrate with an alkaline etchant solution to form an etched metal substrate (22 or 41), the alkaline etchant solution comprising about 2 vol% to about 6 vol% triethanolamine, about 2 vol% to about 30 vol% sodium sulfide additive, about 10 vol% to about 40 vol% 50% sodium hydroxide, about 75 g / L or less dissolved metal content, and about 6 g / L or less ethylenediaminetetraacetic acid (EDTA); deoxidizing the etched metal substrate (22 or 41) with a deoxidizing solution to form a processed metal substrate, the deoxidizing solution comprising about 40 vol% to about 60 vol% nitric acid; performing a second alkaline cleaning on the processed metal substrate; optionally performing alkaline etching cleaning and deoxidizing the etched metal substrate with the alkaline etchant, the deoxidation solution comprising about 40 vol% to about 60 vol% nitric acid, and if necessary, the deoxidation solution can be used alone or in combination with an iron-based or chromium-based deoxidation solution to remove oxides; Depositing a coating (35 or 37) onto the processed metal substrate to form a coated metal substrate (16 or 18), wherein depositing the coating (35 or 37) onto the processed metal substrate comprises electrolytically depositing an inorganic finish thereon, the electrolytic deposition of the inorganic finish comprising: attaching the processed metal substrate to two or more counter electrodes, electrically connecting the processed metal substrate to a power source, The processed metal substrate is immersed in an inorganic coating solution, applying a current density to the processed metal substrate to form a coated metal substrate (16 or 18), and The coated metal substrate (16 or 18) is rinsed.

17. The method of claim 16, wherein the current density applied to the processed metal substrate is about 0.2 mA / cm 2 to about 0.5 mA / cm 2 .

18. The method of claim 16, wherein the current density is applied to the processed metal substrate for about 2 minutes to about 5 minutes.

19. The method of claim 16, wherein the current density is applied to the processed metal substrate as a constant current.

20. A coated metal substrate (16 or 18) comprising: An etched metal substrate (22 or 41), the etched metal substrate (22 or 41) comprising a metal substrate having an average surface roughness of about 79 μin (2 μm) to about 8 μin (0.2 μm), wherein: The average surface roughness of the etched metal substrate (22 or 41) is the result of etching the metal substrate in an etching solution and deoxidizing the metal substrate in a deoxidizing solution comprising about 40 vol% to about 60 vol% nitric acid, and An inorganic finish (35 or 37) disposed on the etched metal substrate (22 or 41), wherein the inorganic finish (35 or 37) comprises a morphology substantially as shown in FIG.

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