CROSS-REFERENCE TO RELATED APPLICATION

[0001] The present application claims priority to and filing benefit of U.S. provisional patent application Ser. No. 62/988,857, filed March 12, 2020, which is incorporated herein by reference in its entirety.

FIELD

[0002] The present disclosure generally relates to electrolytic processing of metallic substrates, such as aluminum alloys, and to systems for carrying out such processing. More specifically, the present disclosure relates to anodizing metallic substrates.

BACKGROUND

[0003] Certain metal products, such as aluminum alloys, can benefit from having an anodized surface. These benefits include durability, color stability, ease of maintenance, aesthetics, health and safety, and low cost. However, it is difficult to anodize aluminum alloy- coils having an anodized film that meets flexibility, durability and/or surface characteristics requirements for downstream processing, including joining of aluminum alloy products. Furthermore, conventional methods for anodizing are time-consuming and require high expense, which reduces the overall efficiency of production processes. In addition, conventional anodizing methods require multiple baths, typically of high concentrations of acid, which contribute to the inefficiency while exposing operators to unsafe conditions. Thus, conventional methods of anodizing are ineffective.

SUMMARY

[0004] Covered embodiments of the invention are defined by the claims, not this summary. This summary is a high-level overview of various aspects of the invention and introduces some of the concepts that are further described in the Deta iled Description section below. This summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to be used in isolation to determine the scope of the claimed subject matter. The subject matter should be understood by reference to appropriate portions of the entire specification, any or all drawings, and each claim. [0005] in one aspect, the present disclosure describes a method of making an anodized substrate, the method comprising: providing a metallic substrate; optionally, cleaning a surface of the metallic substrate; anodizing the surface of the metallic substrate in an electrolyte solution at a temperature from 60 °C to 100 °C to form an anodized film layer, wherein the electrolyte solution comprises from 0.01 Mto 1 M of an electrolyte; and optionally, drying the surface of the metallic substrate. In some cases, the electrolyte is an inorganic acid selected from the group consisting of phosphoric acid, nitric acid, sulfuric acid, phosphonic acid, and combinations thereof. In some cases, the electrolyte solution comprises from 0.05 M to 0.5 M electrolyte, and optionally the electrolyte is phosphoric acid. In some cases, the anodizing comprises applying a direct current (DC) having a voltage from ± 15 VDC to ± 25 VDC and/or applying an alternating current (AC) having a voltage from ± 15 VAC to ± 25 VAC to the electrolyte solution for at least 5 seconds. In some cases, the anodizing comprises applying the AC for at least 5 seconds before and/or after applying the DC for at least 15 seconds. In some cases, cleaning the surface of the metal substrate comprises rinsing the surface of the metallic substrate with a solvent. In some cases, the metallic substrate is not etched before anodizing. In some cases, the metallic substrate comprises an aluminum alloy.

[0006] In another aspect, the present disclosure describes a method of making an anodized substrate, the method comprising: providing a metallic substrate; optionally, cleaning a surface of the metallic substrate; anodizing the surface of the metallic substrate in an electrolyte solution by applying a direct current (DC) having a voltage from ± 15 VDC to ± 25 VDC and/or applying an alternating current (AC) having a voltage from ± 15 VAC to ± 25 VAC/ to the electrolyte solution for at least 5 seconds, wherein the electrolyte solution comprises from 0.01 M to 1 M of an electrolyte; and optionally, drying the surface of the metallic substrate. In some cases, the electrolyte is an inorganic acid selected from the group consisting of phosphoric acid, nitric acid, sulfuric acid, phosphonic acid, and combinations thereof, in some cases, the electrolyte solution comprises from 0.05 M to 0.5 M electrolyte, and optionally the electrolyte is phosphoric acid. In some eases, the anodizing comprises applying the AC for at least 5 seconds before and/or applying the DC for at least 15 seconds. In some cases, the electrolyte solution is heated to a temperature from 60 °C to 100 °C. In some cases, cleaning the surface of the metal substrate comprises rinsing the surface of the metallic substrate with a solvent. In some cases, the metallic substrate is not etched before anodizing. In some cases, the metallic substrate comprises an aluminum alloy.

[0007] in another aspect, the present disclosure describes a system for anodizing a metallic substrate, the system comprising: an electrolytic cell having a metallic cathode; an electrolyte solution source for providing an electrolyte solution comprising from 0.01 M to 1 M of an electrolyte: a support for suspending the metallic substrate in the bath; and a power supply from providing a direct current (DC) and/or alternating current (AC) to the electrolytic cell and through the electrolyte solution. In some cases, the electrolyte solution comprises from 0.05 M to 0.5 M electrolyte, and optionally the electrolyte is phosphoric acid. In some cases, the electrolyte solution source comprises a tank having an agitator. In some cases, the electrolytic cell further comprises one or more compound electrodes.

DETAILED DESCRIPTION

[0008] Described herein are methods and systems for making an anodized substrate from a metallic substrate, such as an aluminum alloy substrate. The resultant anodized substrates can be used, for example, to produce anodized substrate (e.g., anodized aluminum alloy) products that have superior surface qualities and minimized surface defects as compared to products prepared from metallic substrates without an anodized film layer as described herein.

[0009] The methods described herein provide a more efficient means of forming a thin anodized film layer on one or more surfaces of a metallic substrate. Particularly, the methods described herein successfully anodize the metallic substrate without the need for a separate step of etching the metallic substrate (e.g., acid etching and/or electrolytic etching). Furthermore, the methods described herein successfully anodize the metallic substrate using one chemical hath, eliminating the need for multiple chemical baths. These new anodizing methods allow for shorter operation time, improved environmental health and safety, and reduced cost. Furthermore, the anodized substrate produced by the methods described herein exhibit excellent physical properties, such as bond durability, and is suitable for coil-to-coil lines as well as batch processing.

Definitions and Descriptions

[0010] As used herein, the terms “invention,” “the invention,” “this invention” and “the present invention” are intended to refer broadly to all of the subject matter of this patent application and the claims below. Statements containing these terms should be understood not to limit the subject matter described herein or to limit the meaning or scope of the patent claims below.

[0011] In this description, reference is made to alloys identified by aluminum industry designations, such as “senes” or “7xxx.” For an understanding of the number designation system most commonly used in naming and identifying aluminum and its alloys, see “International Alloy Designations and Chemical Composition Limits for Wrought Aluminum and Wrought Aluminum Alloys” or “Registration Record of Aluminum Association Alloy Designations and Chemical Compositions Limits for Aluminum Alloys in the Form of Castings and Ingot,” both published by The Aluminum Association.

[0012] Aluminum alloys are described herein in terms of their elemental composition in weight percentage (wt. %) based on the total weight of the alloy. In certain examples of each alloy, the remainder is aluminum, with a maximum wt. % of 0.15 % for the sum of the impurities.

[0013] As used herein, “bond durability” refers to an ability of a bonding agent bonding two products together to withstand cycled mechanical stress after exposure to environmental conditions that initiate failure of the bonding agent. Bond durability is characterized in terms of the number of mechanical stress cycles applied to the bonded products, while the bonded products are exposed to the environmental conditions, until the bond fails.

[0014] As used herein, terms such as “cast metal product,” “cast product,” “cast aluminum alloy product,” and the like are interchangeable and refer to a product produced by direct chill casting (including direct chill co-casting) or semi-continuous casting, continuous casting (including, for example, by use of a twin belt caster, a twin roll caster, a twin block caster, or any other continuous caster), electromagnetic casting, hot top casting, or any other casting method. [0015] As used herein, a “continuous coil” or an “aluminum alloy continuous coil” refers to an aluminum alloy subjected to a continuous processing method on a continuous line without breaks in time or sequence (i.e., the aluminum alloy is not subjected to batch processing).

[0016] As used herein, a “coil-to-coil” line or “coii-to-coil processing” refers to a continuous processing method on a continuous line whereby the alloy, e.g., aluminum alloy, processed in the method is fed into the processing from a coil, uncoiled during the processing, and re-coiled after completing the processing. f0017j Reference is made in tins application to alloy condition or temper. For an understanding of the alloy temper descriptions most commonly used, see “American National Standards (ANSI) H35 on Alloy and Temper Designation Systems.” An F condition or temper refers to an aluminum alloy as fabricated. An O condition or temper refers to an aluminum alloy after annealing. A T1 condition or temper refers to an aluminum alloy cooled from hot working and naturally aged (e.g., at room temperature). A T2 condition or temper refers to an aluminum alloy cooled from hot working, cold worked, and naturally aged. A T3 condition or temper refers to an aluminum alloy solution heat treated, cold worked, and naturally aged. A T4 condition or temper refers to an aluminum alloy solution heat treated and naturally aged. A T5 condition or temper refers to an aluminum alloy cooled from hot working and artificially aged (at elevated temperatures). A T6 condition or temper refers to an aluminum alloy solution heat treated and artificially aged. A T7 condition or temper refers to an aluminum alloy solution heat treated and artificially overaged. A T8x condition or temper refers to an aluminum alloy solution heat treated, cold worked, and artificially aged. A T9 condition or temper refers to an aluminum alloy solution heat treated, artificially aged, and cold worked.

[0018] As used herein, the meaning of “a,” “an,” or “the” includes singular and plural references unless the context clearly dictates otherwise.

[0019] As used herein, the meaning of “room temperature” can include a temperature of from about 15 °C to about 30 °C, for example about 15 °C, about 16 °C, about 17 °C, about 18 °C, about 19 °C, about 20 °C, about 21 °C, about 22 °C, about 23 °C, about. 24 °C, about 25 °C, about 26 °C, about 27 °C, about 28 °C, about 29 °C, or about 30 °C.

[0020] All ranges disclosed herein are to be understood to encompass any and all subranges subsumed therein. For example, a stated range of “1 to 10” should be considered to include any and all subranges between (and inclusive of) the minimum value of 1 and the maximum value of 10; that is, all subranges beginning with a minimum value of 1 or more, e.g. 1 to 6.1, and ending with a maximum value of 10 or less, e.g., 5.5 to 10.

Metallic Substrate

[0021] As noted, the present disclosure provides methods and systems for making an anodized substrate. More specifically, the methods described herein produce a thin anodized film layer on the surface of a metallic substrate. The composition of the metallic substrate on which the anodized film layer is formed is not particularly limited. The methods described herein are particularly well suited, but not limited, to anodizing an aluminum alloy. The anodized film layer can be applied, for example, to any suitable aluminum alloy, such as a continuous coil of an aluminum alloy. Suitable aluminum alloys include, for example, 1xxx series aluminum alloys, 2xxx series aluminum alloys, 3xxx series aluminum alloys, 4xxx senes aluminum alloys, 5xxx series aluminum alloys, 6xxx series aluminum alloys, 7xxx series aluminum alloys, and 8xxx series aluminum alloys.

[0022] By way of non-limiting example, exemplary Ixxx series aluminum alloys for use as . In some cases, the aluminum alloy is at least 99.9 % pure aluminum (e,g., at least 99.91 %, at least 99.92 %, at least 99.93 %, at least 99.94 %, at least 99.95 %, at least 99.96 %, at least 99,97 %, at least 99.98 %, or at least 99.99 % pure aluminum).

[0023] Non-limiting exemplary' 2xxx series aluminum alloys for use as the metallic substrate

[0024] Non-limiting exemplary 3xxx series aluminum alloys for use as the metallic substrate f0025j Non- limiting exemplary 4xxx series aluminum alloys for use as the metallic substrate

[0026] Non-limiting exemplary 5xxx series aluminum alloys for use as the metallic substrate

[0027] Non-limiting exemplary 6xxx series aluminum alloys for use as the metallic substrate

[0028] Non- limiting exemplary 7xxx series aluminum alloys for use as the metallic substrate

[0029] Non-limiting exemplary 8xxx series aluminum alloys for use as the metallic substrate

[0030] While aluminum alloy products are described throughout the disclosure, the methods and products apply to any metallic substrate. In some embodiments, the metallic substrate is aluminum, an aluminum alloy, magnesium, a magnesium-based material, titanium, a titanium- based material, copper, a copper-based material, steel, a steel-based material, bronze, a bronze- based material, brass, a brass-based material, a composite, a sheet used in composites, or any other suitable metal or combination of materials. The product may include monolithic materials, as well as non-monolithic materials such as roll-bonded materials, clad materials, composite materials, or various other materials. In some examples, the metal article is a metal coil, a metal strip, a metal plate, a metal sheet, a metal billet, a metal ingot, or the like.

[0031] The metallic substrate can be prepared from an alloy of any suitable temper. In certain examples, the alloys can be used in F, O, T3, T4, T6, or T8x tempers. The alloys can be produced by direct chill casting (including direct chill co-casting) or semi-continuous casting, continuous casting (including, for example, by use of a twin belt caster, a twin roll caster, a block caster, or any other continuous caster), electromagnetic casting, hot top casting, or any other casting method.

Anodized Film Laver

[0032] As described above, an anodized film layer is formed by the methods described herein on a surface of the metallic substrate. The anodized film layer includes a barrier layer, which is composed of aluminum oxide (e.g., nonporous aluminum oxide). The barrier layer can be up to about 25 ran m thickness. In some cases, the barrier layer can be from about 1 nm to about 25 nm, from about 5 nm to about 25 nm, from about 10 nm to about 20 nm, or from about 12 nm to about 17 nm in thickness. By way of example, the barrier layer can be about 1 nm, about 2 nm, about 3 nm, about 4 nm, about 5 nm, about 6 nm, about 7 nm, about 8 nm, about 9 nm, about 10 nm, about 11 nm, about 12 nm, about 13 nm, about 14 nm, about 15 nm, about 16 nm, about 17 nm, about 18 nm, about 19 nm, about 20 nm, about 21 nm, about 22 nm, about 23 nm, about 24 nm, or about 25 nm in thickness, or anywhere in between.

[0033] In some cases, the anodized film layer may include a filament layer. The filament layer is composed of aluminum oxide (e.g., porous aluminum oxide) and may be include a senes of column-like, porous structures. The characteristics of the filament layer (e.g., the characteristics of the column-like, porous structures) may be controlled by anodizing parameters and conditions (e.g,, composition of the electrolyte solution). The filament layer can be up to about 75 nm in thickness. In some cases, the filament layer can be from about 5 nm to about 800 nm, from about 10 nm to about 750 nm, from about 25 nm to about 700 nm, or from about 45 nm to about 650 nm in thickness. By way of example, the filament layer can be about 5 nm, about 25 nm, about 50 nm, about 75 nm, about 150 nm, about 200 nm, about 300 nm, about 350 nm, about 400 nm, about 450 nm, about 550 nm, about 600 nm, about 650 nm, about 700 nm, about 750 nm, or about 800 in thickness, or anywhere in between.

[0034] In some cases, the anodized film layer may include a barrier layer of any thickness described above and a filament layer of any thickness described above. In some cases, the anodized film layer includes a barrier layer of about 10 nm, about 15 nm, about 20 nm or about 25 nm and a filament layer of about 650 nm, about 700 nm, about 750 nm, or about 800 nm. By way of example, the anodized film layer may include a barrier layer of about 10 nm and a filament layer of about 650 nm, a barrier layer of about 15 nm and a filament layer of about 700 nm, a barrier layer of about 20 nm and a filament layer of about 750 nm, or a barrier layer of about 25 nm and a filament layer of about 800 nm.

[0035] The thickness of the anodized film layer, including the barrier layer or the barrier layer and the filament layer, can range from about 1 nm to about 1000 nm. in some cases, the anodized film layer is less than about 1000 nm in thickness, e.g., less than about 900 nm, less than about 800 nm, less than about 700 nm, less than about 600 nm, less than about 500 nm, less than about 400 nm, less than about 300 nm, less than about 200 nm, or less than about 100 nm. For example, the anodized film layer can be from about 5 nm to about 1000 nm, from about 10 nm to about 900 nm, from about 20 nm to about 800 nm, or from about 30 nm to about 700 nm m thickness. In some examples, the anodized film layer can be about 1 nm, 5 nm, about 10 nm, about 15 nm, about 20 nm, about 25 nm, about 30 nm, about 35 nm, about 40 nm, about 45 nm, about 50 nm, about 55 nm, about 60 nm, about 65 nm, about 70 nm, about 75 nm, about 80 nm, about 85 nm, about 90 nm, about 95 nm, about 100 nm, about 150 nm, about 250 nm, about 300 nm, about 400 nm, about 500 nm, about 600, about 700, about 750 nm, about 800 nm, about 825 nm, about 850 nm, about 900 nm, about 950 nm, or about 1000 nm in thickness, or anywhere in between.

Methods of Making an Anodized Substrate

[0036] The present disclosure provides methods of making an anodized substrate. The methods of anodizing the metallic substrate, as described herein, include an optional preparation step, an anodizing step, and an optional drying step. As noted above, the methods described herein do not include a separate step of etching the metallic substrate (e.g., acid etching and/or electrolytic etching). Furthermore, the methods can be carried out using one chemical bath, eliminating the need for the multiple chemical baths required in conventional anodizing methods. As a result, these new anodizing methods allow for shorter operation time, improved environmental health and safety, and reduced cost.

[0037] The metallic substrate as described herein can be subjected to processing techniques prior to anodizing to provide the metallic substrate in a form suitable for anodizing. In some cases, for example, processing techniques may be employed to provide a metallic substrate m the form of a continuous coil, including, for example, casting, homogenizing, hot rolling, warm rolling, cold rolling, solution heat treating, annealing, aging (including natural aging and/or artificial aging), any suitable processing techniques, and/or any combinations thereof. Accordingly, anodizing may be performed as a step subsequent to the processing techniques described above to provide the continuous coils or other metallic substrates. For example, the anodizing can be carried out after processing the metal substrate in a cold rolling mill, an annealing furnace, a continuous annealing and solution heat treating (CASH) line, or any suitable final processing equipment. Said another way, the anodizing described herein may occur between a penultimate metal processing step and the coiling of the metal substrate. Thus, the metallic substrate can be processed into a metal product and can be anodized immediately after processing without coiling the metal product (e.g., to provide the continuous coil). In some cases, the metallic substrates described herein can be anodized after coiling. The metallic substrates can be stored (e.g., to naturally age the metallic substrates) or artificially aged before anodizing. In such instances, the metallic substrates (e.g., the stored metallic substrates or the artificially aged metallic substrates) can be uncoiled and fed into the systems described herein for anodizing. [0038] The methods may be employed in a continuous coil process, e.g., where the metallic substrate is composed of one or more continuous coils spliced or joined together. Line speeds for the continuous coil process are variable and can be in the range of about 1 meter per minute (mpm) to about 350 mpm. For example, the line speed can be about 1 mpm, about 2 mpm, about 3 mpm, about 4 mpm, about 5 mpm, about 6 mpm, about 7 mpm, about 8 mpm, about 9 mpm, about 10 mpm, about 15 mpm, about 20 mpm, about 25 mpm, about 30 mpm, about 35 mpm, about 40 mpm, about 45 mprn, about 50 mpm, about 55 mpm, about 60 mpm, about 65 mpm, about 70 mpm, about 75 mpm, about 80 mpm, about 85 mpm, about 90 mpm, about 95 mprn, about 100 rnpm, about 105 mprn, about 110 mpm, about 115 mpm, about 120 mpm, about 125 mpm, about 130 mpm, about 135 mprn, about 140 mpm, about 145 mpm, about 150 mpm, about 155 rnpm, about 160 mpm, about 165 mpm, about 170 mpm, about 175 mpm, about 180 rnpm, about 185 mpm, about 190 mpm, about 195 mpm, about 200 mpm, about 205 mpm, about 210 mpm, about 215 mpm, about 220 mpm, about 225 mpm, about 230 mpm, about 235 mpm, about 240 mpm, about 245 mpm, about 250 mpm, about 255 mpm, about 260 mpm, about 265 mpm, about 270 mpm, about 275 mpm, about 280 mpm, about 285 mpm, about 290 mpm, about 295 mpm, about 300 rnpm, about 305 mpm, about 310 mpm, about 315 mpm, about 320 mpm, about 325 mpm, about 330 mpm, about 335 mpm, about 340 mpm, about 345 mpm, or about 350 mpm, or anywhere in between. Preparation

[0039] Before anodizing, the metallic substrate may undergo a preparation step. The preparation step may prepare the metallic substrate for anodizing. For example, the optional preparation step may include cleaning one or more surfaces of the metallic substrate. The optional cleaning step removes residual oils, or loosely adhering oxides, from the surface of the metallic substrate.

[0040] Optionally, cleaning can be performed using a solvent (e.g., an aqueous or organic solvent) as a cleaner. Suitable cleaners can include, for example, water (e.g., distilled water, demineralized water, or deionized water), an acid (e.g., sulfuric acid, hydrofluoric acid, nitric acid, phosphoric acid, boric acid, or citric acid), a caustic (e.g., sodium hydroxide, potassium hydroxide, calcium oxide, calcium carbonate, calcium hydroxide, lithium hydroxide, magnesium hydroxide, ammonium hydroxide), hexane, ethanol, acetone, or any combination thereof. The cleaner may further comprise one or more additives added to the solvent. In some non-limiting examples, the cleaner can be sprayed onto one or more surfaces of the continuous coil. In some aspects, the cleaning step can be performed by spraying water and/or a cleaning solution onto one or more surfaces of the metallic substrate at a suitable pressure, such as a pressure of from about 2 bar to about 4 bar. For example, the surfaces of the metallic substrate can be sprayed at a pressure of about 2 bar, 2.1 bar, 2.2 bar, 2.3 bar, 2.4 bar, 2.5 bar, 2,6 bar, 2.7 bar, 2.8 bar, 2.9 bar, 3 bar, 3.1 bar, 3.2 bar, 3.3 bar, 3.4 bar, 3.5 bar, 3.6 bar, 3.7 bar, 3.8 bar, 3.9 bar, 4 bar, or anywhere in between. Additionally, the cleaner can be heated prior to application to one or more surfaces of the metallic substrate, in some non-limiting examples, the cleaner can be heated to a temperature of from about 85 °C to about 100 °C. For example, the cleaner can be heated to a temperature of about 85 °C, 86 °C, 87 °C, 88 °C, 89 °C, 90 °C, 91 °C, 92 °C, 93 °C, 94 °C, 95 °C, 96 °C, 97 °C, 98 °C, 99 °C, 100 °C, or anywhere in between.

[0041 ] As noted, the cleaning step is optional. In some cases, the metallic substrate is not subjected to the cleaning step before anodizing. In some cases, the metallic substrate is only subjected to the cleaning step if residual oils are visible on one or more surfaces of the metallic substrate.

[0042 ] The optional preparation step preferably does not include a preparatory etching step.

In conventional methods of anodizing a metallic substrate, the metallic substrate is etched, e.g., by an alkaline solution and/or an electrolyte solution, prior to anodizing to further clean the surface and/or to prepare one or more surfaces of the metal substrate for anodizing. The methods described herein effectively form an anodized film layer on a surface of the metallic substrate without the need for a preparatory etching step. Because the methods described herein do not require the preparatory etching step, the methods described herein require fewer chemical baths than conventional anodizing methods. In most instances, a single chemical bath is required for the anodizing method. This increases the overall efficiency of the processing by reducing both time and expense of carrying out the method. Furthermore, by reducing the need for harsh alkaline and/or acidic baths, the methods described herein provide for improved environmental health and safety.

Anodizing

[0043] In the methods described herein, the metallic substrate is subjected to an anodizing step, whereby an anodized film layer is formed, e.g., on one or more surfaces of the metallic substrate, to form one or more thin anodized film surfaces. In some cases, the thin anodized film surface is a final product. In certain examples, the thin anodized film surface is a substrate for subsequent coatings (e.g., one or more pretreatments including an adhesion promoter, a corrosion inhibitor, a coupling agent, any suitable pretreatment solution, or any combination thereof). The anodizing is accomplished by contacting the surface of the metallic substrate with an electrolyte solution, passing the metallic substrate through the active zone of the one or more electrolytic cells, and flowing an electric current through the electrolyte solution, thereby creating an electrical circuit.

[0044] The electrolyte solution is composed of an aqueous solution of an electrolyte, e.g., an electrolyte dissolved and/or diluted in water. Suitable electrolytes include, for example, inorganic acids such as phosphoric acid, nitric acid, sulfuric acid, phosphonic acid, and combinations of these. Other exemplary' electrolytes include aqueous solutions of sodium nitrate, sodium chloride, potassium nitrate, magnesium chloride, sodium acetate, copper sulfate, potassium chloride, magnesium nitrate, potassium nitrate, calcium chloride, lithium chloride, sodium carbonate, potassium carbonate, calcium carbonate, sodium bicarbonate, ammonium acetate, silver nitrate, ferric chloride, ammonium pentaborate, boric acid, citric acid, ammonium adipate, ammonium phosphate monobasic, or any combination thereof, among others.

[0045] The electrolyte solution includes the electrolyte in an amount from 0.01 M to 1 M. In some non-limiting examples, the electrolyte solution includes the electrolyte in an amount from about 0.01 M to about 1 M, e.g., from 0.01 M to 0.8 M, from 0.01 M to 0.6 M, from 0.01 M to 0.5 M, from 0.01 M to 0.4 M, from 0.01 M to 0.2 M, from 0.02 M to 1 M, from 0.02 M to 0.8 M, from 0.02 M to 0.5 M, from 0.02 M to 0.6 M, from 0.02 M to 0.4 M, from 0.02 M to 0.2 M, from 0.4 M to 1 M, from 0.4 M to 0.8 M, from 0.04 M to 0.6 M, from 0.04 M to 0.5 M, from 0.04 M to 0.4 M, from 0.04 M to 0.2 M, from 0.05 M to 1 M, from 0.05 M to 0.8 M, from 0.05 M to 0.5 M, from 0.05 M to 0.6 M, from 0.05 M to 0.4 M, from 0.05 M to 0.2 M, from 0.06 M to 1 M, from 0.06 M to 0.8 M, from 0.06 M to 0.6 M, from 0.06 M to 0.5 M, from 0.06 M to 0.4 M, from 0.06 M to 0.2 M, from 0.08 M to 1 M, from 0.08 M to 0.8 M, from 0.08 M to 0.6 M, from 0.08 M to 0.5 M from 0.08 M to 0.4 M, or from 0.08 M to 0.2 M. In terms of lower limits, the electrolyte solution may include the electrolyte in an amount greater than 0.01 M, e.g., greater than 0.02 M, greater than 0.04 M, greater than 0.05 M, greater than 0.06 M, or greater than 0.08 M. In terms of upper limits, the electrolyte solution may include the electrolyte in an amount less than 1 M, e.g., less than 0.8 M, less than 0.6 M, less than 0.5 M, less than 0.4 M, or less than 0.2 M. For example, the electrolyte solution may include about 0.08 M electrolyte, about 0.09 M electrolyte, about 0.1 M electrolyte, about 0.12 M electrolyte, about 0.15 M electrolyte, or about 0.18 M electrolyte.

[0046] Each of the above ranges of concentrations of electrolyte in the electrolyte solution is applicable for any of the suitable electrolyte described above. For example, the electrolyte solution may comprise an inorganic acid, such as phosphoric acid, nitric acid, sulfuric acid, phosphomc acid, or combinations thereof, at any of the concentrations disclosed above for the electrolyte m the electrolyte solution.

[0047] The electrolyte solution of the methods described herein includes a lower concentration of electrolyte than electrolyte solutions of conventional anodizing methods. In conventional anodizing methods, electrolyte solutions having an electrolyte concentration of at least about 2 M are typically used. The methods described herein effectively form an anodized film layer on a surface of the metallic substrate without the need for high concentration electrolyte solutions. This further increases the overall efficiency of the processing by reducing the expense of carrying out the method. Furthermore, because conventional anodizing methods typically utilize highly concentrated acid solution, the methods described herein provide for improved environmental health and safety. [0048] The means of passing the metallic substrate through the active zone of one or more electrolytic cells and flowing an electric current through the electrolyte solution is not particularly limited. In some cases, a metallic cathode, e.g., composed of stainless steel, may be used to form an electric circuit with the metallic substrate. In some cases, the metallic cathode may be a contact roll (e.g., a contact roll electrode). The one or more electrolytic cells may also include one or more counter electrodes. For example, an electrolytic cell may comprise a first counter electrode disposed parallel to a first surface of the metallic substrate and a second counter electrode disposed parallel to a second surface of the metallic substrate.

[0049] Power can be applied to the metallic cathode and/or the one or more counter electrodes, thus forming an alternating current (AC) circuit or a direct current (DC) circuit. The current flow in the electrolyte solution releases oxygen ions, which can migrate to a surface of metallic substrate and form a metallic oxide on the surface. For example, the metallic substrate may be composed of an aluminum alloy, and the oxygen ions released due to the flow of AC or DC may combine with aluminum on the surface of the metallic substrate to form alumina (AI2O3). Applying power to the counter electrode(s) can ensure anodization occurs at an interface between the electrolyte and the surface of the metallic substrate.

[0050] In some cases, power is applied to form an AC circuit. The AC power applied to the metallic cathode and/or the one or more counter electrodes can range from about ± 10 Volts AC (VAC) to about ± 35 VAC, e.g., from about ± 15 Volts AC (VAC) to about ± 35 VAC, from about ± 18 VAC to about ± 34 VAC, from about ± 20 VAC to about ± 32 VAC, or from about ± 22 VAC to about ± 30 VAC/ In terms of lower limits, the AC power applied may be greater than ± 15 VAC, e.g., greater than ± 18 VAC, greater than ± 20 VAC, or greater than ± 22 VAC. In terms of upper limits, the AC power applied may be less than ± 35 VAC, e.g., less than ± 34 VAC, less than ± 32 VAC, or less than ± 30 VAC. For example, the AC power applied may be about ± 22 VAC, about ± 24 VAC, about ± 26 VAC, or about ± 28 VAC.

[0051] The metallic substrate can be anodized by applying the AC for a set time, e.g., by- exposing the metallic substrate to the AC for a set time, in some cases, the AC is applied for at least 5 seconds, e.g., at least 6 seconds, at least 7 seconds, at least 8 seconds, or at least 9 seconds. In terms of upper limits, the AC may be applied for less than 5 minutes, e.g., less than 2 minutes, less than 1 minute, less than 30 seconds, or less than 20 seconds. In terms of ranges, the AC may be applied for from 5 seconds to 5 minutes, e.g., from 6 seconds to 2 minutes, from 7 seconds to 1 minute, from 8 seconds to 30 seconds, or from 9 seconds to 20 seconds. For example, the metallic substrate may be exposed to the energized electrolyte solution for about 7 seconds, about 8 seconds, about 9 seconds, about 10 seconds, about 11 seconds, about 12 seconds, about 13 seconds, about 14 seconds, about 15 seconds, about 16 seconds, or about 17 seconds.

[0052] The AC circuit formed may be any waveform, e.g., a sinusoidal waveform, a rectangular waveform, a sawtooth waveform, a triangular waveform, or a square waveform. [0053] In some cases, power is applied to form a DC circuit. The DC power applied to the metallic cathode and/or the one or more counter electrodes can range from about ± 10 Volts DC (VDC) to about ± 35 VDC, e.g., from about ± 15 Volts DC (VDC) to about ± 35 VDC, from about ± 18 VDC to about ± 34 VDC, from about ± 20 VDC to about ± 32 VDC, or from about ± 22 VDC to about ± 30 VDC. In terms of lower limits, the DC power applied may be greater than ± 15 VDC, e.g., greater than ± 18 VDC, greater than ± 20 VDC, or greater than ± 22 VDC. In terms of upper limits, the DC power applied may be less than ± 35 VDC, e.g,, less than ± 34 VDC, less than ± 32 VDC, or less than ± 30 VDC. For example, the DC power applied may be about ± 22 VDC, about ± 24 VDC, about ± 26 VDC, or about ± 28 VDC.

[0054] The metallic substrate can be anodized by applying the DC for a set time, e.g., by exposing the metallic substrate to the DC for a set time. In some cases, the DC is applied for at least 5 seconds, e.g., at least 7 seconds, at least 10 seconds, at least 12 seconds, or at least 15 seconds, in terms of upper limits, the DC may be applied for less than 10 minutes, e.g., less than 5 minutes, less than 2 minutes, less than 1 minute, or less than 30 seconds. In terms of ranges, the DC may be applied for from 5 seconds to 10 minutes, e.g., from 7 seconds to 5 minutes, from 10 seconds to 2 minutes, from 12 seconds to 1 minute, or from 15 seconds to 30 seconds. For example, the metallic substrate may be exposed to the energized electrolyte solution for about 10 seconds, about 12 seconds, about 14 seconds, about 16 seconds, about 18 seconds, about 20 seconds, about 22 seconds, about 24 seconds, about 26 seconds, about 28 seconds, or about 30 seconds.

[0055] in some cases, a surface of the metallic substrate is anodized by applying an AC alone or by applying a DC alone. In some cases, a surface of the metallic substrate is anodized by applying both AC power and DC power, e.g., in sequence. Said another way, anodizing a surface of the metallic substrate may include applying the AC and subsequently applying the DC and/or applying the DC and subsequently applying the AC. For example, the anodizing may include applying the AC for at least 5 seconds before and/or after applying the DC for at least 5 seconds, e.g., applying the AC for about 5 seconds before and/or after applying the DC for about 5 seconds, applying the AC for about 5 seconds before and/or after applying the DC for about 10 seconds, applying the AC for about 5 seconds before and/or after applying the DC for about 15 seconds, applying the AC for about 5 seconds before and/or after applying the DC for about 20 seconds, applying the AC for about 8 seconds before and/or after applying the DC for about 5 seconds, applying the AC for about 8 seconds before and/or after applying the DC for about 10 seconds, applying the AC for about 8 seconds before and/or after applying the DC for about 15 seconds, applying the AC for about 8 seconds before and/or after applying the DC for about 20 seconds, applying the AC for about 10 seconds before and/or after applying the DC for about 5 seconds, applying the AC for about 10 seconds before and/or after applying the DC for about 10 seconds, applying the AC for about 10 seconds before and/or after applying the DC for about 15 seconds, applying the AC for about 10 seconds before and/or after applying the DC for about 20 seconds, applying the AC for about 12 seconds before and/or after applying the DC for about 5 seconds, applying the AC for about 12 seconds before and/or after applying the DC for about 10 seconds, applying the AC for about 12 seconds before and/or after applying the DC for about 15 seconds, or applying the AC for about 12 seconds before and/or after applying the DC for about 20 seconds.

[0056] in some cases, during the anodizing step, the metallic substrate, e.g., a continuous coil or a portion of the metallic substrate (such as a surface of the metallic substrate), may be immersed in a bath of the electrolyte solution. Optionally, the electrolyte solution can be circulated to ensure a fresh solution is continuously exposed to the aluminum alloy continuous coil surfaces.

[0057] The temperature of the electrolyte solution bath can be from about 60 °C to about 100 °C, e.g., from about 65 °C to about 98 °C, from about 70 °C to about 95 °C, from about 75 °C to about 92 °C, from about 70 °C to about 90 °C, or from about 75 °C to about 90 °C. In terms of lower limits, the temperature of the electroly te solution bath may be greater than 60 °C, e.g., greater than 65 °C, greater than 70 °C, or greater than 75 °C. In terms of upper limits, the temperature of the electrolyte solution bath may be less than 100 °C, e.g., less than 98 °C, less than 95 °C, less than 92 °C, or less than 90 °C. For example, the temperature of the electrolyte bath can be about 60 °C, about 61 °C, about 62 °C, about 63 °C, about 64 °C, about 65 °C, about 66 °C, about 67 °C, about 68 °C, about 69 °C, about 70 °C, about 71 °C, about 72 °C, about 73 °C, about 74 °C, about 75 °C, about 76 °C, about 77 °C, about 78 °C, about 79 °C, about 80 °C, about 81 °C, about 82 °C, about 83 °C, about 84 °C, about 85 °C, about 86 °C, about 87 °C, about 88 °C, about 89 °C, about 90 °C, about 91 °C, about 92 °C, about 93 °C, about 94 °C, about 95 °C, about 96 °C, about 97 °C, about 98 °C, about 99 °C, or about 100 °C.

[0058] The concentration of components in the electrolyte solution can be measured according to techniques as known to those of skill in the art, such as by a titration procedure for free and total acid or by inductively coupled plasma (ICP). For example, the aluminum content can be measured by ICP and controlled to be within a certain range. In some examples, the aluminum content is controlled to be less than about 10.0 g/L. For example, the aluminum content can be less than about 9.5 g/L, less than about 9.0 g/L, less than about 8.5 g/L, less than about 8.0 g/L,, less than about 7.5 g/L,, less than about 7.0 g/L, less than about 6.5 g/L, less than about 6.0 g/L, less than about 5.5 g/L, less than about 5.0 g/L, less than about 4.5 g/L, less than about 4.0 g/L,, less than about 3.5 g/L,, less than about 3.0 g/L, less than about 2.5 g/L, less than about 2.0 g/L, less than about 1.5 g/L, less than about 1 .0 g/L, less than about 0.5 g/L, less than about 0.4 g/L,, less than about 0.3 g/L,, less than about 0.2 g/L, or less than about 0.1 g/L.

[0059] In some eases, during the anodizing step, the electrolyte solution may be sprayed onto a surface of the metallic substrate. In some aspects, the electrolyte solution may be sprayed onto the surface of the metallic substrate at a pressure of from about 2 bar to about 4 bar. For example, the electrolyte solution can be sprayed onto the surface at a pressure of about 2 bar, 2, 1 bar, 2.2 bar, 2.3 bar, 2.4 bar, 2.5 bar, 2.6 bar, 2.7 bar, 2,8 bar, 2,9 bar, 3 bar, 3.1 bar, 3.2 bar, 3.3 bar, 3.4 bar, 3.5 bar, 3.6 bar, 3.7 bar, 3.8 bar, 3.9 bar, 4 bar, or anywhere in between.

Additionally, the electrolyte solution can be heated prior to application onto the surface of the metallic substrate, in some non-limiting examples, the electrolyte solution can be heated to a temperature of from about 60 °C to about 100 °C, e.g., from about 65 °C to about 98 °C, from about 70 °C to about 95 °C, from about 75 °C to about 92 °C, from about 70 °C to about 90 °C, or from about 75 °C to about 90 °C. In terms of lower limits, the electrolyte solution may be heated to a temperature greater than 60 °C, e.g., greater than 65 °C, greater than 70 °C, or greater than 75 °C. In terms of upper limits, the electrolyte solution may be heated to a temperature less than about 100 °C, e.g., less than about 98 °C, less than about 95 °C, less than about 92 °C, or less than about 90 °C. For example, the electrolyte solution may be heated to a temperature of 60

°C, 61 °C, 62 °C, 63 °C, 64 °C, 65 °C, 66 °C, 67 °C, 68 °C, 69 °C, 70 °C, 71 °C, 72 °C, 73 °C,

74 °C, 75 °C, 76 °C, 77 °C, 78 °C, 79 °C, 80 °C, 81 °C, 82 °C, 83 °C, 84 °C, 85 °C, 86 °C, 87

°C, 88 °C, 89 °C, 90 °C, 91 °C, 92 °C, 93 °C, 94 °C, 95 °C, 96 °C, 97 °C, 98 °C, 99 °C, or 100

°C.

[0060] The electrolyte solution of the methods described herein, whether as an electrolyte solution bath or spray, is heated to a higher temperature than electrolyte solutions of conventional anodizing methods. In conventional anodizing methods, electrolyte solutions are typically heated to less than 60 °C, for example, about 55 °C. The methods described herein include a higher temperature electrolyte to more efficiently form an anodized film layer on a surface of the metallic substrate. This further increases the overall efficiency of the processing by reducing the expense of carrying out the method.

Post-Treatment

[0061] After anodizing, the metallic substrate may undergo one or more post-treatment steps. The post-treatment step may prepare the anodized substrate for further processing.

[0062] Optionally, after the anodizing step, the surface of the metallic substrate may be rinsed with a solvent. The rinsing step may remove any residual electrolyte remaining after the anodizing step. Suitable solvents include, for example, aqueous solvents (e.g., deionized water), organic solvents, inorganic solvents, pH-specific solvents (e.g., solvents that do not react with the electrolyte), any suitable solvent, or any combination thereof. The rinse can be performed using sprays or by immersion. The solvent can be circulated to remove the residual electrolyte from the aluminum alloy continuous coil surface and to prevent its resettling on the surface. The temperature of the rinse solvent can be any suitable temperature.

[0063] Optionally, after the anodizing step and/or the rinsing step, the surface of the metallic surface may be dried. The drying step removes any electrolyte solution and/or rinsing solvent (e.g., deionized water) from the surface of the coil. In addition, the drying step may increase corrosion resistance and/or adhesion performance of the thin anodized film.

[0064] The drying step can be performed using, for example, compressed air, an air dryer, an infrared dryer, or any other suitable dryer. For air drying the surface of the metallic substrate, e.g., with compressed air, the an may be heated to a temperature from 450 °C to 550 °C, e.g., from 460 °C to 530 °C, from 465 °C to 515 °C, from 470 °C to 500 °C, or from 475 °C to 495 °C. In terms of lower limits, the air, e.g., compressed air, may be heated to a temperature greater than 450 °C, e.g., greater than 460 °C, greater than 465 °C, greater than 470 °C, or greater than

475 °C. In terms of upper limits, the air, e.g., compressed air, may be heated to a temperature less than 550 °C, e.g., less than 530 °C, less than 515 °C, less than 500 °C, or less than 495 °C. For example, the surface of the metallic substrate may be dried with air heated to a temperature of about 470 °C, about 471 °C, about 472 °C, about 473 °C, about 474 °C, about 475 °C, about

476 °C, about 477 °C, about 478 °C, about 479 °C, about 480 °C, about 481 °C, about 482 °C, about 483 °C, about 484 °C, about 485 °C, about 486 °C, about 487 °C, about 488 °C, about 489 °C, about 490 °C, about 491 °C, about 492 °C, about 493 °C, about 494 °C, or about 495 °C. [0065] The drying step can be performed for a time period of up to 5 minutes. For example, the drying step can be performed for 5 seconds or more, 10 seconds or more, 15 seconds or more, 20 seconds or more, 25 seconds or more, 30 seconds or more, 35 seconds or more, 40 seconds or more, 45 seconds or more, 50 seconds or more, 55 seconds or more, 60 seconds or more, 65 seconds or more, 90 seconds or more, two minutes or more, three minutes or more, four minutes or more, or five minutes.

[0066] After anodizing, the anodized substrate may be heat treated and processed to a desired condition or temper. For example, the anodized substrate may be processed to achieve a T1 temper, a T2 temper, a T3 temper, a T4 temper, a T5 temper, a T6 temper, a T7 temper, a T8x temper, or a T9 temper.

System

[0067] The present disclosure also provides systems of making an anodized substrate, in some non-limiting examples, the systems are configured to form an anodized film layer on at least one surface of a metallic substrate, e.g., a first surface of the metallic substrate. The first surface may be a top surface, a bottom surface, or a side surface of a metallic substrate, e.g., a continuous coil prepared in a horizontal processing line. In some cases, the first surface may be a front surface, a rear surface, or a side surface of a metallic substrate prepared in a vertical processing line. In some aspects, the systems described herein are configured to form the anodized film layer on a first side of the metallic substrate and a second side of the substrate. For example, the anodized film layer can be formed on the top surface and the bottom surface of the metallic substrate (e.g., in the horizontal processing line), and/or on the front surface and the rear surface of the metallic substrate (e.g., in the vertical processing line). In further examples, the anodized film layer can be formed on the entirety of the metallic substrate (e.g., any exposed surface of the continuous coil).

[0068] The systems of making an anodized substrate, as described herein, may be a component of a larger processing system. For example, the systems can be positioned downstream of a cold rolling mill, an annealing furnace, a continuous annealing and solution heat treating (CASH) line, or any suitable final processing equipment. Said another way, the system for anodizing the metal substrate described herein may be positioned between a penultimate metal processing equipment and a metal coder. Thus, the metallic substrate can be processed into a metal product and can be anodized immediately after processing without coiling the metal product (e.g., to provide the continuous coil). Accordingly, when the systems described above are placed in sendee in a metal processing line, parameters of the systems can depend on a line speed of the metal processing line, for example, line speeds selected and/or dictated by processes including the homogenization, the solution heat treating, and/or the annealing (i.e., temporally-dependent thermal processes). Thus, system parameters including applied power, electrolyte concentration, electrolyte temperature, and/or dwell time, among others, can be tailored according to the predetermined/selected line speed of the metal processing line. Electrolytic Cell

[0069] The systems described herein include an electrolytic cell (e.g., a bipolar cell). In some cases, a single electrolytic cell is utilized in a processing line to form the anodized film layer in situ. In some cases, a plurality of electrolytic cells can be employed m a processing line. Employing a plurality of electrolytic cells in the processing line (e.g., continuous coil processing line) provides a customizable anodizing system, in some examples, an electrolytic cell can be used to electrolytically clean the metallic substrate. In some cases, the plurality of electrolytic ceils can he used to clean the continuous coil and form the thin anodized film on the continuous coil.

[0070] The electrolytic cell includes a metallic cathode. The metallic cathode is an electrode from which the current employed to anodize the metallic substrate flows. The composition of the metallic cathode is not particularly limited, and conventional cathode materials may be used. Exemplary cathode materials include steel, stainless steel, graphite, titanium, lead, and aluminum alloys. In some cases, the metallic cathode may he a contact roil electrode. [0071] The electrolytic cell may also include a counter electrode. The counter electrode (also called the auxiliary electrode) is an electrode that supports the function of the metallic cathode, e.g., to increase the rate of anodizing. One or more counter electrodes may form a circuit with the metallic cathode when the system is energized. The one or more counter electrodes may be mounted above the surface of the metallic substrate, below the surface of the metallic substrate, or above and below the surface of the metallic substrate, depending on desired anodization. The composition of the counter electrode is not particularly limited, and conventional auxiliary' electrode materials may be used. Exemplary' counter electrode include steel, stainless steel, graphite, titanium, silver, and platinum.

Electrolyte Solution Source

[0072] The systems described herein also include an electrolyte solution source. The electrolyte solution source provides the electrolyte solution through which the electric current formed during anodizing flows. As noted above, the electrolyte solution is composed of an aqueous solution of an electrolyte, e.g., an electrolyte dissolved and/or diluted in water. Suitable electrolytes include, for example, inorganic acids such as phosphoric acid, nitric acid, sulfuric acid, phosphonic acid, and combinations of these. Other exemplary electrolytes include aqueous solutions of sodium nitrate, sodium chloride, potassium nitrate, magnesium chloride, sodium acetate, copper sulfate, potassium chloride, magnesium nitrate, potassium nitrate, calcium chloride, lithium chloride, sodium carbonate, potassium carbonate, calcium carbonate, sodium bicarbonate, ammonium acetate, silver nitrate, ferric chloride, ammonium pentaborate, boric acid, citric acid, ammonium adipate, ammonium phosphate monobasic, or any combination thereof, among others. The electrolyte solution source is preferably composed of a material that is not negatively affected, e.g., corroded by the exemplary electrolyte solutions.

[0073] in some cases, the electrolyte solution source includes a tank, e.g., to form an electrolyte solution bath. During anodizing, the metallic substrate may be immersed in the electrolyte solution bath. The tank may also include an agitator for creating movement within the electrolyte solution bath and for dissipating heat produced during anodization. The agitator may be a conventional agitator known to those in the art. For example, the agitator may be an inlet (e.g., a PVC pipe) for condensed air. In some eases, the electrolyte solution source includes one or more nozzles, e.g., for spraying the electrolyte solution onto a surface of the metallic substrate. Support

[0074] The systems described herein also include one or more supports. The support feeds and/or suspends the metallic substrate in the electrolytic cell. In some cases, the support immerses the metallic substrate in the electrolyte solution bath. The composition of the support is not particularly limited, and conventional cathode materials may be used. Exemplary cathode materials include steel, stainless steel, graphite, titanium, and aluminum alloys.

[0075] In some cases, the support includes one or more rollers for conveying the metallic substrate through the electrolytic cell. For example, the support may include a system of squeegee and/or contact rollers. In some case, the support is a rack that suspends the metallic substrate in the electrolyte solution bath.

Power Source

[0076] The systems described herein also include a power source. The power source is capable of providing an AC and/or a DC to the electrolytic cell. Where the power source provides AC, the power source can form an AC circuit of any waveform, e.g., a sinusoidal waveform, a rectangular waveform, a sawtooth waveform, a triangular waveform, or a square waveform.

Exemplary Configurations

[0077] In one non-limiting example of the system, a metallic substrate is fed into the electrolytic cell by squeegee rollers positioned at an entrance to the electrolytic cell. The squeegee rollers can remove any residual solvent remaining from a preparatory' cleaning step.

The electrolyte for the anodization process is supplied to the surface of the metallic substrate by nozzles disposed above a first side of the metallic substrate and below a second side of the metallic substrate. Coated stainless steel rollers positioned at a midpoint (or other suitable position) in the electrolytic cell stabilize the metallic substrate and continue feeding the metallic substrate through the electrolytic cell. The electrolytic cell, including a first graphite counter electrode and a second graphite counter electrode that are powered by an alternating current (AC) source, supplies current to pass through the electrolyte and anodize the surface of the metallic substrate. Squeegee rollers positioned at an exit of the electrolytic cell can remove residual electrolyte and continue feeding the metallic substrate out of the electrolytic cell.

[0078] in another non-limiting example, a contact roll is used as an electrode to form the circuit to anodize a metallic substrate. The metallic substrate is fed to a contact roll electrode. The electrolyte for anodization is supplied to the surface of the metallic substrate by nozzles disposed above a first side of the metallic substrate and below a second side of the metallic substrate. In a first configuration, the contact roll electrode and a first counter electrode are configured to form a circuit and are powered by a current source configured to supply an AC to pass through the electrolyte and anodize the surface of the metallic substrate. In a second configuration, the contact roll electrode is an anode and the current source is configured to supply a DC to pass through the electrolyte and anodize the surface of the metallic substrate. Squeegee rollers are positioned downstream of the contact roll electrode to remove any residual cleaner solvent from a preparatory cleaning step and continue feeding the metallic substrate through the electrolytic cell, and squeegee rollers are positioned downstream of the first counter electrode to remove residual electrolyte and continue feeding the metallic substrate to any further downstream processing.

[0079] In another non-limiting example, a metallic substrate is placed inside a rack constructed of titanium and secured to an aluminum bar. The rack immerses the metallic substrate m an electrolyte solution bath within a tank. Stainless steel cathodes are used to supply both AC current and DC current received from a pulse reverse power supply through the electrolyte solution bath to anodize one or more surfaces of the metallic substrate. Compressed air is supplied at the bottom the electrolyte solution bath to agitate the electrolyte solution and remove localized heat produced during anodizing.

Use of Anodized Substrate

[0080] The anodized substrates made according to the methods described herein can be used in producing products, including products for use in, among others, automotive, electronics, and transportation applications, such as commercial vehicle, aircraft, or railway applications. The continuous coils and methods described herein provide products with surface properties desired in various applications. The products described herein can have high strength, high deformability (elongation, stamping, shaping, formability, bendability, or hot formability), and/or high resistance to corrosion. Employing a thin anodized film as a surface pretreatment for a continuous coil provides a product that is deformable without damaging the pretreatment. For example, certain polymer based pretreatment films can break during the bending operations used to form an aluminum alloy product. [0081] in certain aspects, the anodized substrates can be coated, e.g., Zn-phosphated and electrocoated (E-coated). The anodized substrates display an improved adhesion of coatings as compared to continuous coils that do not contain an anodized film layer.

[0082] In some further aspects, the anodized substrates display a high level of adhesion of laminates or lacquer films onto the surface of the continuous coils. Additionally, laminates and lacquers can be cured after application at temperatures of up to about 230 °C. The anodized substrates are not damaged by elevated temperatures used in certain downstream processing of aluminum alloy products, providing a thermally resistant pretreatment for aluminum alloy products.

[0083] In some further aspects, the anodized substrates display excellent bond durability. [0084] In some examples, the anodized substrates can be used for chassis, cross-member, and intra-chassis components (encompassing, but not limited to, ail components between the two C channels in a commercial vehicle chassis) to gain strength, serving as a full or partial replacement of high-strength steels. In certain examples, the anodized substrates can be used m O, F, T4, T6, or T8x tempers. In certain aspects, the anodized substrates can be used to prepare motor vehicle body part products, e.g., automobile body parts, such as bumpers, side beams, roof beams, cross beams, pillar reinforcements (e.g., A-pil!ars, B-pillars, and C-pillars), inner panels, side panels, floor panels, tunnels, structure panels, reinforcement panels, inner hoods, or trunk lid panels. The disclosed anodized substrates can also be used in aircraft or railway vehicle applications, to prepare, for example, external and internal panels.

[0085] In some examples, the anodized substrates can also be used to prepare housings for electronic devices, including mobile phones and tablet computers. For example, the anodized substrates can be used to prepare housings for the outer casing of mobile phones (e.g., smart phones) and tablet bottom chassis. Exemplary consumer electronic products include mobile phones, audio devices, video devices, cameras, laptop computers, desktop computers, tablet computers, televisions, displays, household appliances, video playback and recording devices, and the like. Exemplary consumer electronic product parts include outer housings (e.g., facades) and inner pieces for the consumer electronic products.

[0086] In certain aspects, the anodized substrates can further be used to prepare electronic device substrates. For example, an electronic device substrate can include a conductive layer (e.g., an aluminum alloy substrate, such as a continuous coil) and a dielectric layer (e.g., an anodized film layer) for preparing a layer-by-layer (e.g., sandwich-style) electronic device. In some examples, the anodized film layer is configured to provide semiconductive properties to the aluminum alloy substrate. Semiconductive properties can include a tunable and/or tailorable conductivity of a material. In certain cases, the conductivity of a metallic substrate, e.g., a metallic substrate composed of an aluminum alloy, can be decreased by forming an anodized film layer thereon. In some examples, the anodized film layer can render the metallic substrate non-conductive (e.g., an insulator). For example, while the aluminum alloy is inherently conductive, the anodized film layer deposited onto the aluminum alloy substrate, including AhOy is a non-conductive and/or high-dielectric (i.e., high-k) film. The anodized film layer can be deposited on at least a portion of at least one surface of the aluminum alloy substrate. In some cases, an entire surface of the metallic substrate can include the anodized film layer. For example, the anodized film layer can be rationally patterned on the surface of an aluminum alloy substrate to define an electronic device area. In some examples, the anodized film layer can have any shape suitable for providing an electronic device substrate, or the metallic substrate can be cut to any suitable shape to provide the electronic device substrate.

[0087] In certain aspects, the anodized film layer has a uniform thickness across the surface of the metallic substrate. The dielectric properties of thin films (e.g., anodized film layers) can be dependent on the parameters of the thin film. For example, the dielectric properties can he proportional to the surface area of the device and/or the device substrate and inversely proportional to the thin film thickness. Thus, providing a stable and uniform electronic device substrate requires providing a uniform anodized film layer. Additionally, the anodized film layer conforms to the surface morphology (e.g., surface roughness) further providing the uniform thickness across the area of the electronic device and/or the electronic device substrate. The dielectric properties of the anodized film layer are inversely proportional to the thickness. Thus, thinner portions of the thin anodized film can experience dielectric breakdown and/or film damage when an electric field and/or electric current is applied.

[0088] In some examples, the anodized film layer has a uniform dielectric constant (k) across the area of the aluminum alloy. In certain aspects, the anodized film layer has a breakdown voltage of at least about ± 10 volts (V) (e.g., at least about ± 11 V, at least about ± 12 V, at least about ± 13 V, at least about ± 14 V, at least about ± 15 V, at least about ± 16 V, or at least about ± 17 V). A breakdown voltage is a voltage at which, when applied to an electronic device having the thin anodized film described herein, the dielectric properties of the anodized film layer are overcome by the applied voltage and electric current can flow across the dielectric layer (e.g., the anodized film layer). For example, a capacitor includes two conductive electrodes having a dielectric layer disposed between the electrodes. When a voltage is applied to the capacitor, electrons accumulate on one electrode until the electric field is strong enough to drive the electrons across the dielectric layer, discharging the capacitor. Thus, when a capacitor discharges, dielectric breakdown occurs in the dielectric layer.

[0089] In further examples, the anodized film layer is configured to minimize a leakage current in an electronic device. For example, the anodized film layer can have a leakage current of up to about ± 100 nanoAinperes (nA) (e.g., up to 90 nA, up to 80 nA, up to 70 nA, up to 60 nA, up to 50 nA, up to 40 nA, up to 30 nA, up to 20 nA, up to 10 nA, up to 1 nA, up to 90 picoAmperes (pA), up to 50 pA, or up to I pA). A leakage current is an amount of current that can propagate across the dielectric layer (e.g., the thin anodized film) at applied voltages that are less than the breakdown voltage. In some cases, device defects and/or other device irregularities can allow current to leak through the dielectric layer, indicated as a leakage current. The anodized film layers described herein allow a negligible amount of current to leak through the dielectric layer.

[0090] In some cases, the anodized film layer is stable under an applied frequency of up to 100 megaHertz (MHz) (e.g., up to 90 MHz, up to 80 MHz, up to 70 MHz, or up to 60 MHz). Thus, high frequency electricity applied to the thin anodized film will not damage the anodized film layer when a device using the electronic device substrates described herein are placed in service (e.g., when used as a capacitor in a circuit).

[0091] In some non-limiting examples, the electronic device substrate comprises a substrate for an energy storage device, a substrate for an energy harvesting device, a substrate for an energy consuming device, or a substrate for a circuit component. For example, the energy storage device can be a capacitor, a supercapacitor, a battery, and/or a rechargeable battery. In some cases, the energy harvesting device can be a photovoltaic device. Further, the energy consuming device can be a light-emitting diode, an organic light-emitting diode, a memory module, an electro-audio device, and/or an electrochromic device. In further examples, the circuit component can be a diode, a rectifying diode, a resistor, a transistor, a memristor, any suitable circuit component, or any combination thereof. lllustrations

[0092 ] Illustration 1 is a method of making an anodized substrate, the method comprising: providing a metallic substrate; and anodizing a surface of the metallic substrate in an electrolyte solution at a temperature from 60 °C to 100 °C to form an anodized film layer, wherein the electrolyte solution comprises from 0.01 M to 1 M of an electrolyte.

[0093] Illustration 2 is the method of any preceding or subsequent illustration, wherein the electrolyte is an inorganic acid selected from the group consisting of phosphoric acid, nitric acid, sulfuric acid, phosphonic acid, and combinations thereof.

[0094] Illustration 3 is the method of any preceding or subsequent illustration, wherein the electrolyte solution comprises from 0.05 M to 0.5 M electrolyte, and wherein the electrolyte is phosphoric acid.

[0095] Illustration 4 is the method of any preceding or subsequent illustration, wherein the anodizing comprises applying a direct current (DC) having a voltage from ± 10 VDC to ± 35 VDC and/or applying an alternating current (AC) having a voltage from ± 10 VAC to ± 35 VAC to the electrolyte solution for at least 5 seconds,

[0096] Illustration 5 is the method of any preceding or subsequent illustration, wherein the anodizing comprises applying the AC for at least 5 seconds before and/or after applying the DC for at least 15 seconds.

[0097] Illustration 6 is the method of any preceding or subsequent illustration, further comprising: cleaning the surface of the metallic substrate; and/or drying the surface of the metallic substrate.

[0098] Illustration 7 is the method of any preceding or subsequent illustration, wherein cleaning the surface of the metal substrate comprises rinsing the surface of the metallic substrate with a solvent.

[0099] Illustration 8 is the method of any preceding or subsequent illustration, wherein the metallic substrate is not etched before anodizing.

[0100] Illustration 9 is the method of any preceding or subsequent illustration, wherein the metallic substrate comprises an aluminum alloy.

[0101] Illustration 10 is a method of making an anodized substrate, the method comprising: providing a metallic substrate; anodizing a surface of the metallic substrate in an electrolyte solution by applying a direct current (DC) having a voltage from ± 10 VDC to ± 35 VDC and applying an alternating current (AC) having a voltage from ± 10 VAC to ± 35 VAC to the electrolyte solution for at least 5 seconds, wherein the electrolyte solution comprises from 0.01 M to 1 M of an electrolyte; and optionally, drying the surface of the metallic substrate.

[0102] Illustration 11 is the method of any preceding or subsequent illustration, wherein the electrolyte is an inorganic acid selected from the group consisting of phosphoric acid, nitric acid, sulfuric acid, phosphonie acid, and combinations thereof.

[0103] Illustration 12 is the method of any preceding or subsequent illustration, wherein the electrolyte solution comprises from 0.05 M to 0.5 M electrolyte, and wherein the electrolyte is phosphoric acid.

[0104] Illustration 13 is the method of any preceding or subsequent illustration, wherein the anodizing comprises applying the AC for at least 5 seconds before and/or after applying the DC for at least 15 seconds.

[0105] Illustration 14 is the method of any preceding or subsequent illustration, wherein the electrolyte solution is heated to a temperature from 60 °C to 100 °C,

[0106] Illustration 15 is the method of any preceding or subsequent illustration, further comprising: cleaning the surface of the metallic substrate; and/or drying the surface of the metallic substrate.

[0107] Illustration 16 is the method of any preceding or subsequent illustration, wherein cleaning the surface of the metal substrate comprises rinsing the surface of the metallic substrate with a solvent.

[0108] Illustration 17 is the method of any preceding or subsequent illustration, wherein the metallic substrate is not etched before anodizing.

[0109] Illustration 18 is the method of any preceding or subsequent illustration, wherein the metallic substrate comprises an aluminum alloy.

[0110] Illustration 19 is a system for anodizing a metallic substrate, the system comprising: an electrolytic cell having a metallic cathode; an electrolyte solution source for providing an electrolyte solution comprising from 0.01 M to 1 M an electrolyte; a support for suspending the metallic substrate in the electrolyte solution; and a power supply from providing a direct current (DC) and alternating current (AC) to the electrolytic cell and through the electrolyte solution. [0111] illustration 20 is the system of any preceding or subsequent illustration, wherein the electrolyte solution comprises from 0.05 Mto 0.5 M electrolyte, and wherein the electrolyte is phosphoric acid.

[0112] ] Illustration 21 is the system of any preceding or subsequent illustration, wherein the electrolyte solution source comprises a tank having an agitator.

[0113] Illustration 22 is the system of any preceding or subsequent illustration, wherein the electrolytic cell further comprises one or more compound electrodes.

EXAMPLES

[0114] The following examples will serve to further illustrate the present invention without, however, constituting any limitation thereof. On the contrary, it is to be clearly understood that resort may be had to various embodiments, modifications, and equivalents thereof which, after reading the description herein, may suggest themselves to those of ordinary skill in the art without departing from the spirit of the invention.

Example 1: Bond Durability Testing

[0115] As noted above, the methods of anodizing metallic substrates described herein produce anodized substrates that demonstrate excellent bond durability. This example serves to illustrate the improvement of the bond durability of metallic substrates anodized according to the methods described herein relative to metallic substrates anodized according to conventional methods.

[006] Several samples of an anodized 7xxx series aluminum alloy were prepared according to the methods described herein to test the properties of the anodized metallic substrate. Each of the samples tested is shown in Table 1. In some samples, a 7xxx series aluminum alloy at F temper was anodized and subsequently heat treated to a T6 temper (485°C for 5 minutes, then 125°C for 24 hours). In other samples, a 7xxx senes aluminum alloy at T6 temper was anodized without subsequent heat treatment. In other samples, a 7xxx senes aluminum alloy at T6 temper was anodized and subsequently heat treated comparably to a T6 temper (485°C for 5 minutes, then 125°C for 24 hours).

[0117] As shown m Table 1, two comparative samples were also prepared according to conventional anodizing methods. In particular, a first comparative sample was prepared by a conventional, two-step phosphoric acid anodizing method, and a second comparative sample was prepared by a conventional sulfuric acid anodizing method.

Table 1

[0118] The three samples of exemplary anodized substrates were subjected to bond durability testing. In this testing, a set of 6 lap joints/bonds of each sample were connected in sequence by bolts and positioned vertically in a 90% relative humidity (RH) humidity cabinet. The temperature was maintained at 50 °C. A force load of 2.4 kN was applied to the bond sequence. The bond durability test is a cyclic exposure test that is conducted for up to 60 cycles. Each cycle lasts for 24 hours. In each cycle, the bonds are exposed in the humidity cabinet for 22 hours, then immersed in 5% NaCl for 15 minutes, and finally air-dried for 105 minutes. Upon the breaking of three joints, the test is discontinued for the particular set of joints and is indicated as a first failure. For this disclosure, the completion of 45 cycles without a first failure indicates that the set of joints passed the bond durability test.

[0119] The bond durability test results are shown below in Table 2. In Table 2, each of the joints are numbered 1 through 6, where joint 1 is the top joint and joint 6 is the bottom joint when oriented vertically. The number in the cells, except for “45” and “60,” indicates the number of successful cycles before a break. The number “45” in a cell indicates that the joints remained intact for 45 cycles. The number “60” in a cell indicates that the joints remained intact for 60 cycles. The results are summarized in Table 2 below:

Table 2

[0120] The exemplary anodized substrates winch were anodized according to the present disclosure demonstrated excellent bond durability, surviving 60 test cycles without failure. The comparative anodized substrates demonstrated comparatively poorer bond durability.