Surface treatment for electrolytic inorganic finishes

Abstract

To provide novel substrate surface treatment methods and compositions for application of inorganic finishes to large metal products and structural components.SOLUTION: In at least one aspect, a method includes: degreasing a metal substrate; performing a first alkaline cleaning on the metal substrate; etching the metal substrate by electropolishing techniques or with an alkaline etchant so as to form an etched metal substrate, where the etched metal substrate comprises an average surface roughness (Ra) of about 8 μin (0.2 μm) to about 16 μin (0.4 μm); deoxidizing the etched metal substrate to form a processed metal substrate; performing alkaline cleaning on the processed metal substrate; optionally performing etch-cleaning and deoxidizing if needed so as to remove oxides; and depositing a coating on the processed metal substrate to form a coated metal substrate.SELECTED DRAWING: None

Description

[Technical field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of and priority to U.S. Provisional Patent Application No. 63 / 526,368, filed July 12, 2023, which is incorporated by reference in its entirety into this specification.

[0002] Field This disclosure relates to methods and compositions for the surface treatment of substrates. [Background technology]

[0003] background

[0003] Aircraft manufacturing requires efficient assembly processes to build large metal products or structural component parts of said products. In aircraft manufacturing, holes for each component can be drilled individually and then the components can be assembled into a stack and attached to each other, eliminating the traditional requirement of having to stack and align components twice, which is associated with conventional assembly methods. However, while efficient assembly processes reduce manufacturing time and costs, the large metal products and structural components produced from such assembly processes are still susceptible to corrosion and environmental degradation throughout processing, assembly, and use.

[0004]

[0004] The application of inorganic finishes is widely used to reduce and / or eliminate corrosion and environmental degradation that may result from the processing, assembly, and use of such large metal products and structural components. However, the processes and surface treatments typically performed to apply such coatings (e.g., pickling solutions) can have undesirable effects on the surface of the substrate to which the coating is applied.

[0005]

[0005] Therefore, there is a need to develop new substrate surface treatment methods and compositions for applying inorganic finishes to large metal articles and structural components.

[0006]

[0006] References for citation are the following disclosure statements (37 C.FR 1.97(h)): U.S. Patent Nos. 11,155,928, 11,303,047, 11,661,665, and U.S. Patent Application Nos. 16 / 721,081 and 12 / 137,948. Summary of the Invention

[0007] The present disclosure relates to methods and compositions for treating substrate surfaces.

[0008] In at least one embodiment, the method includes degreasing a metal substrate, performing a first alkaline clean on the metal substrate, and etching the metal substrate with an alkaline etchant to form an etched metal substrate, wherein the etched metal substrate has an average surface roughness (R a ), pickling the etched metal substrate to form a treated metal substrate, performing a second alkaline clean on the treated metal substrate, and optionally performing additional etch cleans and pickling to remove oxides and deposit a coating on the treated metal substrate to form a coated metal substrate.

[0009] In at least one embodiment, the method includes degreasing the metal substrate; performing a first alkaline clean on the metal substrate; etching the metal substrate with an alkaline etchant to form an etched metal substrate, the alkaline etchant 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); pickling the etched metal substrate with a pickling solution comprising about 40 vol % to about 60 vol % nitric acid, which may be used alone or in combination with an iron-based or chromate pickling solution, to form a treated metal substrate; performing a second alkaline clean on the treated metal substrate; and optionally performing an additional etching clean with an alkaline etchant to form an etched metal substrate, the alkaline etchant 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). % 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 of dissolved metal content, and about 6 g / L or less of ethylenediaminetetraacetic acid (EDTA); pickling the etched metal substrate with a pickling solution containing about 40 vol % to about 60 vol % nitric acid, which may be used alone or in combination with an iron-based or chromate pickling solution, to form a treated metal substrate; and depositing a coating on the pickled metal substrate to form a coated metal substrate.

[0010] In at least one embodiment, the method includes degreasing a metal substrate; performing a first alkaline clean on the metal substrate; etching the metal substrate with an alkaline etchant to form an etched metal substrate, the alkaline etchant 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); and pickling the etched metal substrate with a pickling solution to form a treated metal substrate, the pickling solution comprising about 40 vol % to about 60 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). % nitric acid used alone or in combination with an iron-based or chromate pickling agent; and depositing a coating on the treated metal substrate to form a coated metal substrate, wherein depositing the coating on the treated metal substrate comprises electrolytically depositing an inorganic finish thereon, the electrolytic deposition of the inorganic finish comprising attaching the treated metal substrate to two or more counter electrodes, electrically connecting the treated metal substrate to a power source, immersing the treated metal substrate in the inorganic finishing solution, applying a current density to the treated metal substrate to form a coated metal substrate, and rinsing the coated metal substrate.

[0011]

[0011] In at least one embodiment, the coated metal substrate comprises an etched metal substrate having an average surface roughness of about 79 μin (2 μm) to about 8 μin (0.2 μm), the average surface roughness of the metal substrate being obtained by etching the metal substrate in an etching solution and pickling in a pickling solution comprising about 40 vol % to about 60 vol % nitric acid, and an inorganic finish disposed on the etched metal substrate, the inorganic finish having a configuration substantially as shown in FIG. 2.

[0012] So that the above-mentioned features of the present disclosure may be understood in detail, a more particular description of the present disclosure, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the accompanying drawings. It should be noted, however, that the accompanying drawings depict only typical embodiments of the present disclosure and therefore should not be considered limiting of its scope, as the present disclosure admits of other equally effective embodiments. [Brief description of the drawings]

[0013] [Figure 1]

[0013] FIG. 2 is a cross-sectional schematic diagram of a structural assembly prior to fastening using a fastening system. [Diagram 2]

[0014] 1 shows a representative example of an aluminum substrate that was subjected to chemical etching using an alkaline etchant composition and pickling using a pickling solution having 50 vol % HNO3. [Diagram 3]

[0015] 1 shows a representative example of an aluminum substrate that has been subjected to chemical etching with a pickling composition and pickling using a pickling solution having a chromate pickling component. [Figure 4]

[0016] 7 shows a 7075-T6 aluminum metal substrate that has been chemically etched with an alkaline etchant composition, pickled with a pickling solution having 50 vol % HNO3, and electrolytically coated with an inorganic finish after 336 hours in a neutral salt fog environment. [Diagram 5]

[0017] FIG. 1 shows a 2024-T3 aluminum metal substrate that has been chemically etched with an alkaline etchant composition, pickled with a pickling solution having 50 vol % HNO3, and electrolytically coated with an inorganic finish after 336 hours in a neutral salt fog environment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014]

[0018] This involves individually pre-forming (e.g., pre-drilling) holes in different structural elements (also referred to herein as substrates) (e.g., at geographically remote locations, at different times, at different locations within the same geographic area, etc.) and then assembling (e.g., aligning, stacking, and fastening) the structural elements together after the holes have been formed to form a structural assembly.

[0015]

[0019] As shown diagrammatically in FIG. 1, the apparatus 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), which are fastened to each other via the fastening system. In one or more embodiments, the structural assembly 12 can be assembled to form one or more components of an aircraft, a spacecraft, a land vehicle, an engine, a propulsion structure, a space re-entry vehicle and / or structures thereof, a power generating turbine, or combinations thereof. In some embodiments, the structural assembly 12 can be one or more of connectors and / or fittings, such as: a fuel tank fitting, a wing fitting, a fuselage fitting, a side of the fuselage fitting, and a large connector.

[0016]

[0020] 1, the at least two structural elements include two structural elements, a first structural element 16 and a second structural element 18. However, in other embodiments, the structural assembly 12 includes more than two structural elements, such as three, four, five, six, seven, or eight or more structural components, that are fastened together by a fastening system. Additionally, the first structural element 16 further includes a first structural element sidewall 22 and a first structural element hole sidewall 35. The second structural element 18 further includes a second structural element sidewall 41 and a second structural element hole sidewall 37. In some such embodiments, more than two components are preformed, stacked, assembled, and then fastened together.

[0017]

[0021] At least a portion of the second structural element 18 is disposed adjacent to the first structural element 16 such that at least a portion of the first structural element 16 and a portion of the second structural element 18 are in direct physical contact / contact with one another. Due to their complexity, the first structural element 16 and the second structural element 18 in some embodiments comprise components of the same aircraft part (e.g., both structural elements may be components of a fuel tank). However, in other embodiments, the first structural element 16 and the second structural element 18 comprise components of different adjacent aircraft parts (e.g., a wing and a fuel tank, a wing and an engine, a wing and a fuselage, etc.), and in some such embodiments, the first structural element 16 and the second structural element 18 are secured to one another to connect the different aircraft parts. Collectively, the first structural element 16 and the second structural element 18 form the structural assembly 12.

[0018]

[0022] 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 assembly of the structural elements into the structural assembly 12. In particular, 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 only one each of the first structural element hole 48 and second structural element hole 50 is shown in FIG. 1, in other embodiments, the first structural element 16 and the second structural element 18 include a plurality of the first structural element holes 48 and the second structural element holes 50. In some such embodiments, the number of first structural element holes 48 and second structural element holes 50 included in first structural element 16 and second structural element 18 will depend on the size and shape of the structural assembly 12 and the level of fixation desired for a particular application.

[0019]

[0023] Prior to assembly, it may be desirable to deposit a coating on one or more structural elements of a structural assembly. Those skilled in the art will appreciate that the method of coating a substrate may include a variety of method processes, depending on the substrate to be coated, the composition of the coating, and the method of implementing the coating deposition. In some embodiments, the method of depositing a coating on one or more structural elements includes one or more substrate cleaning processes, one or more substrate surface treatment processes, and one or more coating deposition processes. The shape and structure of the substrate can be selected arbitrarily according to the parameters associated with the assembly process, and is not limited to being planar. For example, the substrate may have a non-planar shape and have a surface to which a coating can be applied. In one or more embodiments, the substrate is a metal substrate selected from aluminum, aluminum alloys, or mixtures thereof.

[0020]

[0024] In one or more aspects, the metal substrate is subjected to a cleaning step that includes degreasing the substrate. The metal substrate can be degreased using any degreaser, such as, for example, acetone or an aqueous alkaline degreaser. This step includes immersing the metal substrate in the degreaser for about 5 to about 30 minutes, hand washing with a cloth, and applying ultrasonic agitation for about 5 to about 20 minutes until no grease remains on their surfaces. In addition, hot air may be used to dry the metal substrate after the degreasing step. In some embodiments, the metal substrate can be degreased using solvent vapor degreasing, vacuum cycle nucleation (VCN), and combinations thereof.

[0021]

[0025] In one or more embodiments, 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 4215 NC LT Aero and 0 to 0.25 wt. % of Bonderite C-AD 4215 Aero, for a period ranging from about 5 minutes to about 30 minutes. In at least one embodiment, the alkaline cleaning is performed at a temperature of about 40° C. to about 60° C.

[0022]

[0026] The cleaned metal substrate may be etched via one or more etching methods known to those skilled in the art, such as chemical etching, pickling, physical abrasion, mechanical polishing, machining, electropolishing, or a combination thereof.

[0023]

[0027] In some embodiments, the cleaned metal substrate is chemically etched to form an etched metal substrate using an alkaline etchant. In at least one embodiment, the alkaline etchant comprises about 2 vol % to about 6 vol %, e.g., about 2 vol % to about 4 vol %, of triethanolamine. In at least one embodiment, the alkaline etchant comprises about 2 vol % to about 30 vol %, e.g., about 10 vol % to about 20 vol %, of sodium sulfide additive. In at least one embodiment, the alkaline etchant comprises about 10 vol % to about 40 vol %, e.g., about 15 vol % to about 20 vol %, of 50% sodium hydroxide additive. In at least one embodiment, the alkaline etchant comprises about 0 g / L to about 75 g / L, e.g., about 75 g / L or less of dissolved metal content. In at least one embodiment, the alkaline etchant comprises about 6 g / L or less of ethylenediaminetetraacetic acid (EDTA).

[0024]

[0028] In one or more embodiments, chemical etching of the cleaned metal substrate is carried out via immersing the cleaned metal substrate in an alkaline etchant for about 1 minute to about 10 minutes, e.g., about 2 minutes to about 7 minutes. In some embodiments, chemical etching of the cleaned metal substrate includes heating the cleaned metal substrate, the alkaline etchant, or both, to a temperature of about 30° C. to about 55° C., e.g., about 35° C. to about 50° C.

[0025]

[0029] In some embodiments, the cleaned metal substrate is physically abraded and / or mechanically polished to form an etched metal substrate. In one or more embodiments, the physical abrasion process can include dry blasting the metal substrate with one or more of alumina grit, silicon carbide grit, glass beads, steel grit, and combinations thereof. In one or more alternative embodiments, the metal substrate can be manually and / or mechanically polished with emery paper to remove powder remaining on the surface of the metal substrate via any suitable method.

[0026]

[0030] In some embodiments, the cleaned metal substrate is etched via immersion in a nitric acid / HF solution according to PS12050.1 Sec. 3.3.1, which is incorporated herein by reference.

[0027]

[0031] In one or more embodiments, the cleaned metal substrate surface is etched to a desired surface roughness via any one or more electropolishing techniques known to those of skill in the art.

[0028]

[0032] In one or more embodiments, the etched metal substrate is subjected to an acid pickling process to form a treated metal substrate. The acid pickling process involves pickling an aluminum substrate with, for example, nitric acid (HNO ) in the range of 35% to 50% by weight. 3 ) for a period of 1 to 5 minutes and / or for a period of 1 to 10 minutes in a pickling agent, e.g., Bonderite C-IC SmutGo NC Aero, a non-chromium deoxidizer, in the range of 18% to 20% by weight. In some embodiments, the etched metal substrate was pickled via immersion in a deoxidizing bath containing the non-chromium deoxidizer BONDERITE C-IC SmutGo AERO ACID for about 4 minutes to about 12 minutes. The pickling process may be carried out, for example, at a temperature in the range of about 20° C. to about 50° C. Thereafter, the aluminum substrate may be rinsed, for example, first with tap water and then with deionized water. In some embodiments, pickling the etched metal substrate includes immersing the etched metal substrate in a pickling 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 pickling solution for about 1 minute to about 10 minutes, e.g., about 7 minutes.

[0029]

[0033] In some embodiments, the treated metal substrate is subjected to an alkaline cleaning. The alkaline cleaning can be performed by immersing the treated metal substrate in an aqueous alkaline cleaner, such as, for example, Bonderite C-AK 4215 NC LT Aero in the range of 38 to 60 g / L and Bonderite C-AD 4215 Aero in the range of 0 to 0.25 wt %, for a period of about 5 minutes to about 30 minutes, such as about 10 minutes to about 20 minutes. In at least one embodiment, 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., and the metal substrate, the aqueous alkaline cleaner, or both, are heated. In some embodiments, the alkaline cleaning solution has a pH of about 10 to about 12.

[0030]

[0034] In some embodiments, the surface roughness component of the treated metal substrate texture as defined by ASME B46.1 has an average surface roughness (R ) of about 500 μinch (13 μm) or less, such as about 400 μinch (10 μm) or less, such as about 300 μinch (7.6 μm) or less, for example about 250 μinch (6.4 μm) or less, such as about 200 μinch (5.1 μm) or less, for example about 150 μinch (3.8 μm) or less, such as about 100 μinch (2.5 μm) or less, for example about 50 μinch (1.3 μm) or less, such as about 25 μinch (0.6 μm) or less, for example about 10 μinch (0.3 μm) or less, such as about 5 μinch (0.13 μm) or less, for example about 2.5 μinch (0.1 μm) or less, such as about 1 μinch (0.03 μm) or less. aIn one or more alternative embodiments, the treated metal substrate has a thickness of about 250 μinch (6.4 μm) to about 0.001 μinch (0.025 nm), such as about 200 μinch (5.1 μm) to about 0.005 μinch (0.13 nm), for example about 100 μinch (5.1 μm) to about 0.005 μinch (0.13 nm). (2.5 μm) to about 0.01 μinch (0.25 nm), for example from about 50 μinch (1.3 μm) to about 0.025 μinch (0.64 nm), for example from about 25 μinch (0.6 μm) to about 0.05 μinch (1.3 nm), for example from about 10 μinch (0.3 μm) to about 0.075 μinch (1.9 nm), for example from about 5 μinch (0.13 μm) to about 0.1 μinch (2.5 nm), for example from about 2.5 μinch (0.1 μm) to about 0.15 μinch (3.8 nm), for example from about 2 μinch (0.05 μm) to about 0.2 μinch (0.01 μm). a has.

[0031]

[0035] In some embodiments, the treated metal substrate is t =R v +R p (In the formula, R v is R a is the absolute value of the maximum valley depth measured from R p is R a The sum of the maximum peak and minimum valley (R t In some embodiments, the treated metal substrate has an R of about 550 μinch (14 μm) to about 710 μinch (18 μm), e.g., about 590 μinch (15 μm) to about 670 μinch (17 μm). t In one or more alternative embodiments, the treated metal substrate has an R of about 197 μinch (5 μm) to about 394 μinch (10 μm), alternatively about 158 ​​μinch (4 μm) to about 236 μinch (6 μm), alternatively about 236 μinch (6 μm) to about 315 μinch (8 μm). t has.

[0032]

[0036] In some embodiments, a coating is deposited on the treated metal substrate. The treated metal substrate is secured to a rack made of a suitable conductive material and immersed in a coating solution. In at least one embodiment, the coating solution is an inorganic finishing liquid. In addition, a bus bar made of a suitable conductive material is suspended above the inorganic finishing liquid. Two or more counter electrodes are attached to the bus bar so that the electrodes are immersed in the solution within one foot of the work surface. The counter electrodes are immersed at a shallower depth than the part to avoid high current density areas on the part. In addition, the bus bar is electrically connected to a rectifier to impart the desired polarity (cathode or anode) to the counter electrode.

[0033]

[0037] In addition, the rack with the treated metal substrate secured thereto is electrically connected to a rectifier such that the rack is at the opposite polarity of the counter electrode. The rectifier is then powered for the entire duration of the inorganic finishing process. Once the inorganic finishing deposition is complete, the rectifier is turned off and the rack is disconnected from the rectifier and removed from the inorganic finishing solution. The coated metal substrate is then removed from the rack, rinsed with water and / or any suitable solvent, and dried via any suitable method known to those skilled in the art. Alternatively, the rack and busbar may be electrically connected to a rectifier, which is powered before the rack is immersed in the inorganic finishing solution. In some embodiments, the rack may be removed at the end of the inorganic finishing process while the rectifier is on.

[0034]

[0038] In some embodiments, the treated metal substrate is immersed in an inorganic finishing solution and supplied with a current density to deposit a coating on the treated metal substrate. In one or more embodiments, the treated metal substrate is immersed in a MIL-DTL-81706 Type II conversion coating solution, where the conversion coating solution is an inorganic finishing solution. In some embodiments, the current density supplied to the treated metal substrate during deposition of the coating is supplied by a suitable DC power supply in a constant current mode, a pulsed current mode, or a combination thereof to provide a cathodic or anodic current density.

[0035]

[0039] In one or more embodiments, the current density supplied to the treated metal substrate is about 0.2 mA / cm 2 to about 0.5 mA / cm 2 , for example, about 0.25 mA / cm 2 to about 0.45 mA / cm 2 In at least one embodiment, the constant current is applied to the treated metal substrate for a period of about 2 minutes to about 5 minutes, such as about 2.5 minutes to about 4 minutes.

[0036]

[0040] In one or more embodiments, the current density is applied to the treated metal substrate by using a constant voltage until a desired potential threshold is reached to sufficiently deposit the coating on the substrate. In one or more embodiments, the voltage applied to the metal substrate is about 0.5V to about 10V, such as about 1.0V to about 8V, such as about 1.5V to about 6V, such as about V to about 2V, such as about 4V to about 3V. In at least one aspect, the voltage is applied to the treated metal substrate for about 30 seconds to about 10 minutes, such as about 1 minute to about 8 minutes, such as about 2 minutes to about 6 minutes, such as about 2 minutes to about 4 minutes, such as about 2 minutes to about 3 minutes.

[0037]

[0041] Once the coating deposition process is complete, the coated metal substrate is removed, rinsed, and dried via one or more suitable methods known to those of skill in the art.

[0038]

[0042] In some embodiments, the coating of the coated metal substrate is about 0.05 mg / cm 2 to about 0.11 mg / cm 2 , for example about 0.07 mg / cm 2 to about 0.09 mg / cm 2 The film has a mass of .

[0039]

[0043] The coating deposited on the coated metal substrate provides corrosion protection. When operated in accordance with ASTM B117, the coating applied to the treated metal substrate provides corrosion protection in a salt fog environment for at least 336 hours without the formation of pits having a diameter greater than 0.031 inches, without the formation of more than 5 pits in a 30 square inch area, and / or without the formation of more than 15 pits in a 150 square inch area. In one or more embodiments, the coating deposited on the coated metal substrate provides such corrosion protection for at least about 336 hours, for example, from about 500 hours to about 800 hours.

[0040] Additional Aspects

[0044] The present disclosure provides, inter alia, the following aspects, each of which may be considered to optionally include any alternative aspects.

[0041] Article 1. Degreasing the metal substrate; performing a first alkaline clean on the metal substrate; Etching the metal substrate with an alkaline etchant to form an etched metal substrate, wherein the etched metal substrate has an average surface roughness (R a Etching a metal substrate having a pickling the etched metal substrate to form a treated metal substrate; Optionally performing a second alkaline clean on the treated metal substrate; and Depositing a coating onto the treated metal substrate to form a coated metal substrate. The method includes:

[0042] Clause 2. The method of clause 1, wherein the alkaline etching 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, a dissolved metal content of about 75 g / L or less, and about 6 g / L or less ethylenediaminetetraacetic acid (EDTA).

[0043] Clause 3. The treated metal substrate has an average surface roughness R of about 8 μin (0.2 μm) to about 79 μin (2 μm). a 3. The method of claim 1 or 2,

[0044] Clause 4. The sum of the maximum peak and the minimum valley on the surface of the treated metal substrate (R t 4. The method of any of clauses 1 to 3, wherein the thickness of the first and second electrodes is from about 158 ​​μinch (4 μm) to about 236 μinch (6 μm).

[0045] Clause 5. The method of any of clauses 1 to 4, wherein pickling the etched metal substrate comprises immersing the etched metal substrate in a pickling solution comprising about 40 vol % to about 60 vol % nitric acid.

[0046] Clause 6. Depositing a coating on the treated metal substrate includes electrolytically depositing an inorganic finish thereon, the electrolytic deposition of the inorganic finish comprising: attaching the treated metal substrate to a counter electrode; electrically connecting the treated metal substrate to a power source; immersing the treated metal substrate in an inorganic finishing solution; applying a current density to the treated metal substrate to form a coated metal substrate; removing the coated metal substrate from the inorganic finishing solution; and Rinsing the coated metal substrate any of the methods set out in clauses 1 to 5, including

[0047] Clause 7. The method of any of clauses 1 to 6, wherein the current density is applied to the treated metal substrate for about 2 minutes to about 5 minutes.

[0048] Clause 8. Any of the methods of clauses 1 to 7, wherein the coating applied to a metal substrate provides corrosion protection in a salt fog environment for a minimum of 336 hours with no pits having a diameter of about 0.031 inches or less, no more than 5 pits within 30 square inches, and no more than 15 pits within an area of ​​150 square inches.

[0049] Clause 9. Any of the methods of clauses 1 through 8, wherein the coating applied to a metal substrate provides corrosion protection in a salt fog environment for a minimum of 336 hours with no pits having a diameter of about 0.031 inches or less, no more than 5 pits within 30 square inches, and no more than 15 pits within an area of ​​150 square inches.

[0050] Article 10. Degreasing the metal substrate; performing a first alkaline clean on the metal substrate; Etching the metal substrate with an alkaline etchant to form an etched metal substrate, the alkaline etchant 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 of dissolved metal content, and about 6 g / L or less of ethylenediaminetetraacetic acid (EDTA); pickling the etched metal substrate with a pickling solution comprising about 40 vol % to about 60 vol % nitric acid, which may be used alone or in combination with an iron-based or chromate pickling solution, to form a treated metal substrate; performing a second alkaline clean on the treated metal substrate, optionally using said alkaline etchant to perform the second alkaline clean; pickling the etched metal substrate with a pickling solution containing about 40 vol % to about 60 vol % nitric acid, which may be used alone or in combination with an iron-based or chromate pickling solution to remove oxides as needed, to form a treated metal substrate; and depositing the coating onto the pickled metal substrate to form a coated metal substrate; The method includes:

[0051] Clause 11. The method of claim 1, wherein depositing a coating on the treated metal substrate includes electrolytically depositing an inorganic finish thereon, the electrolytic deposition of the inorganic finish comprising: Attaching the treated metal substrate to a counter electrode (cathode); electrically connecting the treated metal substrate to a power source; immersing the treated metal substrate in an inorganic finishing solution; applying a current density to the treated metal substrate to form a coated metal substrate; removing the coated metal substrate from the inorganic finishing solution; and Rinsing the coated metal substrate The methods of Article 10, including:

[0052] Clause 12. The treated metal substrate has an R of about 8 μin (0.2 μm) to about 79 μin (2 μm). a 10 or 11.

[0053] Clause 13. Surface R of treated metal substrate t 13. The method of any of clauses 10 to 12, wherein the thickness is from about 158 ​​μinch (4 μm) to about 236 μinch (6 μm).

[0054] Clause 14. The method of any of clauses 10 to 13, wherein the current density is applied to the treated metal substrate for about 2 minutes to about 5 minutes.

[0055] Clause 15. Any of the methods of clauses 10 to 14, wherein the coating applied to a metal substrate provides corrosion protection in a salt fog environment for a minimum of 336 hours with no pits having a diameter of about 0.031 inches or less, no more than 5 pits within 30 square inches, and no more than 15 pits within an area of ​​150 square inches.

[0056] Article 16. Degreasing the metal substrate; performing a first alkaline clean on the metal substrate; Etching the metal substrate with an alkaline etchant to form an etched metal substrate, the alkaline etchant 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., of 50% sodium hydroxide), a dissolved metal content of about 75 g / L or less, and about 6 g / L or less ethylenediaminetetraacetic acid (EDTA); pickling the etched metal substrate with a pickling solution to form a treated metal substrate, the pickling solution comprising about 40 vol % to about 60 vol % nitric acid; performing a second alkaline clean on the treated metal substrate, optionally performing an alkaline etching clean with said alkaline etchant and pickling the etched metal substrate with a pickling solution comprising about 40 vol % to about 60 vol % nitric acid, which may be used alone or in combination with an iron-based or chromate pickling solution, to remove oxides as needed; depositing a coating on the treated metal substrate to form a coated metal substrate, comprising electrolytically depositing an inorganic finish thereon, the electrolytic deposition of the inorganic finish comprising: attaching the treated metal substrate to two or more counter electrodes; electrically connecting the treated metal substrate to a power source; immersing the treated metal substrate in an inorganic finishing solution; applying a current density to the treated metal substrate to form a coated metal substrate; and Rinsing the coated metal substrate depositing a coating on the treated metal substrate, The method includes:

[0057] Clause 17. The current density applied to the treated metal substrate is about 0.2 mA / cm 2 to about 0.5 mA / cm 2That is, the method of clause 16.

[0058] Clause 18. The method of clause 16 or 17, wherein the current density is applied to the treated metal substrate for about 2 minutes to about 5 minutes.

[0059] Clause 19. The method of any of clauses 16 to 18, wherein the current density is applied to the treated metal substrate as a constant current.

[0060] Article 20. Degreasing the metal substrate; performing a first alkaline clean on the metal substrate; Etching the metal substrate by electropolishing techniques or with an alkaline etchant to ensure removal of 5 μm to 13 μm of material to form an etched metal substrate, wherein the etched metal substrate has an average surface roughness (R a Etching a metal substrate having a pickling the etched metal substrate to form a treated metal substrate; Optionally performing a second alkaline clean on the treated metal substrate; and Depositing a coating onto the treated metal substrate to form a coated metal substrate. The method includes:

[0061] Article 21. 1. An 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): an etched metal substrate, the average surface roughness of the metal substrate being obtained by etching the metal substrate in an etching solution and pickling the metal substrate in a pickling solution containing about 40 vol % to about 60 vol % nitric acid; and 3. An inorganic finish disposed over an etched metal substrate, the conversion coating comprising a configuration substantially as shown in FIG. A coated metal substrate comprising: EXAMPLES

[0062] Sample preparation

[0045] The 7050-T7451, 7075-T6, and 2024-T3 aluminum specimens were machined to the desired size and shape, degreased, cleaned with acetone, and subjected to an alkaline clean to produce cleaned aluminum substrates. The cleaned aluminum substrates were chemically etched using an alkaline etchant composition containing triethanolamine, sodium sulfide additive, sodium hydroxide, metal inclusions, and ethylenediaminetetraacetic acid. The etched aluminum substrates were then subjected to an acid pickling process, where each specimen was etched in approximately 50 vol % HNO 3 The steel was immersed in a pickling composition having about 50 vol % HNO 3 It is important to note that by using a pickling composition having the formula: the aluminum substrate is not etched but the intermetallic compounds are attacked.

[0063] For comparison, additional cleaned aluminum substrates were chemically etched using pickling solution compositions and processes in accordance with PS 12050.1 Each of the etched metal specimens was then subjected to a pickling process in which the pickling solution contained a chromate pickling component.

[0064] surface analysis Before and after etching and pickling the substrate, the pickled aluminum substrate was observed using a stylus-type (surface contact) profilometer and a white light interferometer to analyze the surface properties of the substrate. The former method for characterizing the surface roughness utilizes a stylus of a defined diameter that is drawn in contact with the substrate surface a distance of 0.25 mm to 0.8 mm and is performed using instruments such as the Mitutoyo Surftest, while the latter method is a non-contact surface morphology that relies on the interference of light waves from a light source and reflected light from the substrate to estimate the surface roughness and is performed using instruments such as the Bruker Contour GT-K 3D Optical Microscope. Figure 2 shows the results of chemical etching using an alkaline etchant composition and 50 vol % HNO 3FIG. 3 shows a representative example of an aluminum substrate that has been subjected to chemical etching with a pickling solution having a chromate pickling component and pickling with a pickling solution having a chromate pickling component.

[0065] Electrolytic Coating The pickled aluminum substrates were coated using an electrolytic coating process in which the substrates were placed on a titanium alloy rack and immersed in SurTec 650 inorganic finishing solution. A suitable DC power supply was connected to the titanium alloy rack and two 1000 series aluminum counter electrodes. The power supply was then turned on to provide a current of 1.0 mA / cm. 2 A constant voltage was applied providing a cathodic or anodic current density not exceeding 100 μm. The duration of coating formation was 10 minutes or less before the power was turned off and the coated aluminum substrate was removed from the inorganic finishing solution. The coated aluminum substrate was then rinsed and dried.

[0066] Salt Fog Test The performance of the coatings was evaluated according to the neutral salt fog test outlined in ASTM B117. A coating applied to an aluminum metal substrate was determined to pass the MIL-A-8625 standard if it had no pits greater than 0.031 inches in diameter, no more than 5 pits in a 30 inch square area, and no more than 15 pits in a 150 inch square area for a minimum of 336 hours in a neutral salt fog environment. Here, a pit is defined as a pit with visible black spots or white corrosion products around it, or a tail-shaped pit. Figures 4 and 5 show the results of chemical etching using an alkaline etchant composition, 50 vol % HNO after 336 hours in a neutral salt fog environment. 3 1 shows 7075-T6 and 2024-T3 aluminum metal substrates that have been pickled using a pickling solution having the formula:

[0067]

[0050] Unless otherwise specified, the terms "consisting essentially of" and "consisting essentially of" do not exclude other steps, elements, or materials, whether or not specifically mentioned in this specification, unless such other steps, elements, or materials affect the basic and novel characteristics of the disclosure, and in addition do not exclude impurities and variations normally associated with the elements and materials used.

[0068]

[0051] As used herein, numerical ranges are inclusive of the numbers recited in the range. For example, the numerical range "1 wt % to 10 wt %" includes both 1 wt % and 10 wt % within the recited range.

[0069]

[0052] For the sake of brevity, only some ranges are explicitly disclosed herein. However, a range from any lower limit can be combined with any upper limit to describe a range that is not explicitly described, and a range from any lower limit can be combined with any other lower limit to describe a range that is not explicitly described, and similarly, a range from any upper limit can be combined with any other upper limit to describe a range that is not explicitly described. In addition, a range includes every point or individual value between its endpoints, even if not explicitly described. Thus, every point or individual value can be combined with any other point or individual value or any other lower or upper limit to be its own lower or upper limit to describe a range that is not explicitly described.

[0070]

[0053] All numerical values ​​contained in the Detailed Description section of this specification are modified by "about" preceding the indicated value to take into account experimental error and variations that would be anticipated by one of ordinary skill in the art.

[0071]

[0054] All documents described herein, including any priority documents and / or test procedures, are incorporated herein by reference to the extent that they do not contradict the text of this specification. As is apparent from the general description and specific embodiments set forth above, several forms of the disclosure have been illustrated and described, but various modifications can be made without departing from the principles and scope of the disclosure. It is therefore intended that the disclosure not be limited thereby. Similarly, the term "comprising" is synonymous with the term "including" for purposes of U.S. law. Similarly, whenever a composition, element, or group of elements "comprises," it is assumed that the same composition, element, or group of elements "consists essentially of," "consists of," "is selected from," or "is" that composition, element, or group of elements, and vice versa.

[0072]

[0055] While the present disclosure has been described with respect to multiple aspects and examples, it will be understood that a person skilled in the art having the benefit of this disclosure may devise other aspects which do not depart from the scope and principles of the present disclosure.

Claims

1. Degreasing the metal substrate; performing a first alkaline wash on the metal substrate; Etching the metal substrate with an alkaline etching solution to form an etched metal substrate (22 or 41), wherein the etched metal substrate (22 or 41) has an average surface roughness (R ａ Etching the metal substrate with pickling the etched metal substrate (22 or 41) to form a treated metal substrate; Optionally performing a second alkaline wash on the treated metal substrate; and depositing a coating (35 or 37) onto the treated metal substrate to form a coated metal substrate (16 or 18); The method includes:

2. 10. The method of claim 1, wherein the alkaline etchant 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 %, a dissolved metal content of about 75 g / L or less, and about 6 g / L or less ethylenediaminetetraacetic acid (EDTA).

3. The treated metal substrate has an average surface roughness R of about 8 μinch (0.2 μm) to about 16 μinch (0.4 μm). ａ 2. The method of claim 1, comprising:

4. The sum of the maximum peak and the minimum valley of the surface of the treated metal substrate (R ｔ 2. The method of claim 1, wherein the thickness of the first and second electrodes is from about 158 ​​μinch (4 μm) to about 236 μinch (6 μm).

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

6. Depositing the coating (35 or 37) on the treated metal substrate comprises electrolytically depositing an inorganic finish thereon, the electrolytic deposition of the inorganic finish comprising: attaching the treated metal substrate to a counter electrode; electrically connecting the treated metal substrate to a power source; immersing the treated metal substrate in an inorganic finishing solution; applying a current density to the treated 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 rinsing said coated metal substrate (16 or 18); The method of claim 1 , comprising:

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

8. 2. The method of claim 1, wherein the coating (35 or 37) applied to the metal substrate provides corrosion protection in a salt fog environment for a minimum of 336 hours with no pits having a diameter of about 0.031 inches or less, fewer than 5 pits within 30 square inches, and fewer than 15 pits within an area of ​​150 square inches.

9. 7. The method of claim 6, wherein the coating (35 or 37) applied to the metal substrate provides corrosion protection in a salt fog environment for a minimum of 336 hours with no pits having a diameter of about 0.031 inches or less, fewer than 5 pits within 30 square inches, and fewer than 15 pits within an area of ​​150 square inches.

10. Degreasing the metal substrate; performing a first alkaline wash on the metal substrate; Etching the metal substrate with an alkaline etchant to form an etched metal substrate (22 or 41), the alkaline etchant 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 %, a dissolved metal content of about 75 g / L or less, and about 6 g / L or less ethylenediaminetetraacetic acid (EDTA); pickling the etched metal substrate (22 or 41) with a pickling solution comprising about 40 vol % to about 60 vol % nitric acid to form a treated metal substrate; performing a second alkaline clean on the treated metal substrate, optionally using the alkaline etchant and a pickling solution comprising about 40 vol % to about 60 vol % nitric acid, which may be used alone or in combination with an iron-based or chromate pickling solution, to remove oxides as needed, and a nitric acid pickling solution, either alone or in combination with other pickling solutions, to remove oxides as needed; depositing a coating (35 or 37) onto said pickled metal substrate to form a coated metal substrate (16 or 18); The method includes:

11. depositing a coating (35 or 37) on the treated metal substrate comprises electrolytically depositing an inorganic finish thereon, the electrolytic deposition of the inorganic finish comprising: attaching the treated metal substrate to a counter electrode; electrically connecting the treated metal substrate to a power source; immersing the treated metal substrate in an inorganic finishing solution; applying a current density to the treated 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 rinsing said coated metal substrate (16 or 18); The method of claim 10, comprising:

12. The treated metal substrate has an R of about 8 μinch (0.2 μm) to about 16 μinch (0.4 μm). ａ 11. The method of claim 10, comprising:

13. R of the surface of the treated metal substrate ｔ 11. The method of claim 10, wherein the thickness is from about 158 ​​μinch (4 μm) to about 236 μinch (6 μm).

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

15. 12. The method of claim 11, wherein the coating (35 or 37) applied to the metal substrate provides corrosion protection in a salt fog environment for a minimum of 336 hours with no pits having a diameter of about 0.031 inches or less, fewer than 5 pits within 30 square inches, and fewer than 15 pits within an area of ​​150 square inches.

16. Degreasing the metal substrate; performing a first alkaline wash on the metal substrate; Etching the metal substrate with an alkaline etchant to form an etched metal substrate (22 or 41), the alkaline etchant 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 %, a dissolved metal content of about 75 g / L or less, and about 6 g / L or less ethylenediaminetetraacetic acid (EDTA); pickling the etched metal substrate (22 or 41) with a pickling solution to form a treated metal substrate, the pickling solution comprising about 40 vol % to about 60 vol % nitric acid; performing a second alkaline clean on the treated metal substrate, optionally using the alkaline etchant and a pickling solution comprising about 40 vol % to about 60 vol % nitric acid, which may be used alone or in combination with an iron-based or chromate pickling solution, to remove oxides as needed; depositing a coating (35 or 37) on said treated metal substrate to form a coated metal substrate (16 or 18), wherein depositing a coating (35 or 37) on said treated metal substrate comprises electrolytically depositing an inorganic finish thereon, said electrolytic deposition of said inorganic finish comprising: attaching the treated metal substrate to two or more counter electrodes; electrically connecting the treated metal substrate to a power source; immersing the treated metal substrate in an inorganic finishing solution; applying a current density to the treated metal substrate to form a coated metal substrate (16 or 18); and rinsing said coated metal substrate (16 or 18); depositing a coating (35 or 37) onto the treated metal substrate, comprising: The method includes:

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

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

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

20. An 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), an etched metal substrate (22 or 41), the average surface roughness of the etched metal substrate (22 or 41) being obtained by etching the metal substrate in an etching solution and pickling the metal substrate in a pickling solution containing about 40 vol % to about 60 vol % nitric acid; an inorganic finish (35 or 41) disposed on said etched metal substrate (22 or 41), said inorganic finish (35 or 41) having a configuration substantially as shown in FIG. A coated metal substrate (16 or 18).

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