Anodization methods and techniques

Abstract

Exemplary methods and techniques anodize a metallic substrate. Exemplary metallic substrates may include aluminum or aluminum alloys. The formation of a metal oxide layer on the metallic substrate may occur in an electrolytic system. Exemplary electrolytic systems may comprise at least one electrode connected to a voltage-generating device and an aqueous acid solution. Exemplary aqueous acid solutions may comprise phosphoric acid, boric acid, and water.

Description

Attorney Docket No. 027808-9082-W001ANODIZATION METHODS AND TECHNIQUESCROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims priority to U.S. Provisional Patent Application No. 63 / 717,183, filed on November 6, 2024, the entire contents of which are incorporated herein by reference.TECHNICAL FIELD

[0002] The present disclosure relates to anodization methods and techniques. Exemplary methods and techniques may generate a metal oxide layer on a metallic substrate.INTRODUCTION

[0003] Metallic surfaces of certain commercial products may be treated to generate surface layers that impart functional, physical, and / or cosmetic attributes. One example of a surface treatment method is anodization.

[0004] Anodizing a metal surface converts a portion of the metal surface into a metal oxide, thereby creating a metal oxide layer. Anodized metal surfaces may provide increased corrosion resistance and wear resistance.SUMMARY

[0005] In some aspects, the techniques described herein relate to a method for anodizing a wheel, the method including: submerging the wheel into an aqueous acid solution, wherein the aqueous acid solution includes phosphoric acid, boric acid, and water; and applying a voltage to the aqueous acid solution, thereby forming a layer of metal oxide on a surface of the wheel.

[0006] In some aspects, the techniques described herein relate to an article, including: a metallic substrate including aluminum or an aluminum alloy; and a metal oxide layer on a surface of the metallic substrate, wherein the metal oxide layer has a thickness of 20 to 120 nanometers.

[0007] Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways.Attorney Docket No. 027808-9082-W001BRIEF DESCRIPTION OF THE DRAWINGS

[0008] FIG. 1 is a schematic diagram of an exemplary electrolytic system.

[0009] FIG. 2 is a graph showing gloss (SGU) after anodization of an aluminum wheel in the presence of phosphoric acid and either 4 g / L or 8 g / L boric acid (HB).

[0010] FIG. 3 is a graph showing gloss (SGU) and percent (%) gloss drop after experimental anodization of an aluminum wheel in the presence and absence of boric acid (HB).

[0011] FIG. 4 is a graph showing gloss (SGU) and % gloss drop of an aluminum wheel after experimental anodization (left) and application of a silicon-containing organic polymer coating (right) in the presence and absence of boric acid (HB).

[0012] FIG. 5 is a graph showing field emission scanning auger microprobe (FESAM) data indicating relative amounts of oxygen (O), carbon (C), aluminum (Al), phosphorous (P), and boron (B) after anodization of an aluminum wheel in the presence of 10% phosphoric acid and 4 g / L boric acid (HB).DETAILED DESCRIPTION

[0013] Methods and techniques disclosed and contemplated herein relate to anodizing an article. In some instances, exemplary methods and techniques may be combined with other techniques to generate a coated metallic article. Exemplary methods and techniques may electrochemically generate a metal oxide layer in an aqueous electrolyte comprising phosphoric acid and boric acid.I. Definitions

[0014] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. In case of conflict, the present document, including definitions, will control. Methods and materials are described below, although methods and materials similar or equivalent to those described herein can be used in practice or testing of the present disclosure. All publications, patent applications, patents and other references mentioned herein are incorporated by reference in their entirety. The materials, methods, and examples disclosed herein are illustrative only and not intended to be limiting.

[0015] The terms “comprise(s),” “include(s),” “having,” “has,” “can,” “contain(s),” and variants thereof, as used herein, are intended to be open-ended transitional phrases, terms, or wordsAttorney Docket No. 027808-9082-W001 that do not preclude the possibility of additional acts or structures. The singular forms “a,” “an” and “the” include plural references unless the context clearly dictates otherwise. The present disclosure also contemplates other embodiments “comprising,” “consisting of’ and “consisting essentially of,” the embodiments or elements presented herein, whether explicitly set forth or not.

[0016] The modifiers “about” or “approximately” used in connection with a quantity are inclusive of the stated value and has the meaning dictated by the context (for example, it includes at least the degree of error associated with the measurement of the quantity). These modifiers should also be considered as disclosing the range defined by the absolute values of the two endpoints. For example, the expression “from about 2 to about 4” also discloses the range “from 2 to 4.” The term “about” may refer to plus or minus 10% of the indicated number. For example, “about 10%” may indicate a range of 9% to 11%, and “about 1” may mean from 0.9-1.1. Other meanings of “about” may be apparent from the context, such as rounding off, so, for example “about 1” may also mean from 0.5 to 1.4.

[0017] For the recitation of numeric ranges herein, each intervening number there between with the same degree of precision is contemplated. For example, for the range of 6-9, the numbers 7 and 8 are contemplated in addition to 6 and 9, and for the range 6.0-7.0, the numbers 6.0, 6.1, 6.2, 6.3, 6.4, 6.5, 6.6, 6.7, 6.8, 6.9, and 7.0 are contemplated. For another example, when a pressure range is described as being between ambient pressure and another pressure, a pressure that is ambient pressure is expressly contemplated.

[0018] Definitions of specific functional groups and chemical terms are described in more detail below. For purposes of this disclosure, the chemical elements are identified in accordance with the Periodic Table of the Elements, CAS version, Handbook of Chemistry and Physics, 104thEd., inside cover, and specific functional groups are defined as described therein.IL Exemplary Materials

[0019] Exemplary materials used during exemplary methods include metallic substrates and aqueous acid solutions. Various aspects of exemplary metallic substrates and aqueous acid solutions are discussed below.Attorney Docket No. 027808-9082-W001A. Metallic Substrates

[0020] Exemplary methods and techniques disclosed herein may be applied to metallic substrates.

[0021] In various instances, exemplary metallic substrates comprise aluminum or an aluminum alloy. In some instances, exemplary aluminum alloys may comprise one or more of: magnesium, silicon, copper, manganese, iron, chromium, titanium, and / or zinc, with the balance aluminum and incidental elements and impurities. In some instances, exemplary aluminum alloys may be a 6xxx series alloys. In some instances, exemplary 6xxx series alloys may comprise aluminum, magnesium, silicon, or combinations thereof. In some instances, exemplary 6xxx series alloys further comprise copper, manganese, iron, chromium, titanium, or combinations thereof. In some instances, exemplary aluminum alloy may be 6061 or 6099. In some instances, exemplary aluminum alloys may be 7xxx series alloys. In some instances, the 7xxx series alloys may contain higher levels of copper and zinc than 6xxx alloys.B. Aqueous Acid Solutions

[0022] Exemplary aqueous acid solutions may comprise phosphoric (H3PO4). In various embodiments, the phosphoric acid is concentrated phosphoric acid. In various instances, the phosphoric acid used to make exemplary aqueous acid solutions may be 85 wt.% concentrated acid in water.

[0023] In various instances, exemplary aqueous acid solutions may comprise phosphoric acid in a molarity amount of about 0.73 M to about 4.4 M. In various instances, exemplary aqueous acid solutions may comprise phosphoric acid in a molarity amount of 0.73 M to 4.4 M, 0.73 M to 4.0 M, 0.73 M to 3.5 M, 0.73 M to 3.0 M, 0.73 M to 2.5 M, 0.73 M to 2.0 M, 0.73 M to 1.5 M, 0.73 M to 1.0 M, 1.5 M to 4.4 M, 2.0 M to 4.4 M, 2.5 M to 4.4 M, 3.0 M to 4.4 M, 3.5 M to 4.4 M, 1.0 M to 2.0 M, 1.1 M to 2.25 M, 2.0 M to 3.0 M, or 3.0 M to 4.0 M. In various instances exemplary aqueous acid solutions may comprise phosphoric acid in a molarity amount no greater than 4.4 M; no greater than 4.0 M; no greater than 3.5 M; no greater than 3.0 M, no greater than 2.5 M, no greater than 2.25 M, no greater than 2.0 M, no greater than 1.5 M, no greater than 1.0 M, or no greater than 0.8 M. In various instances, exemplary aqueous acid solutions may comprise phosphoric acid in a molarity amount no less than 0.73 M, no less than 1.0 M, no less than 1.5 M,Attorney Docket No. 027808-9082-W001 no less than 2.0 M, no less than 2.5 M, no less than 3.0 M, no less than 3.5 M, no less than 4.0 M, or no less than 4.3 M.

[0024] In various instances, exemplary aqueous acid solutions may comprise phosphoric acid in an amount of about 5 to about 30 volume percent (vol.%). In various instances, exemplary aqueous acid solutions may comprise phosphoric acid in an amount of 5 vol.% to 15 vol.%, 5 vol.% to 20 vol.%, 5 vol.% to 25 vol.%, 8 vol.% to 12 vol%, 7 vol.% to 15 vol.%, 7 vol.% to 20 vol.%, 7 vol.% to 25 vol.%, 5 vol.% to 30 vol.%, 7 vol.% to 30 vol.%, 10 vol.% to 15 vol.%, 10 vol.% to 20 vol.%, 10 vol.% to 25 vol.%, 10 vol.% to 30 vol.%, 15 vol.% to 20 vol.%, 15 vol.% to 25 vol.%, 15 vol.% to 30 vol.%, 20 vol.% to 25 vol.%, or 20 vol.% to 30 vol.%. In various instances exemplary aqueous acid solutions may comprise phosphoric acid in an amount no greater than 30 vol.%, no greater than 25 vol.%, no greater than 20 vol.%, no greater than 15 vol.%, no greater than 10 vol.%, or no greater than 5 vol.%. In various instances, exemplary aqueous acid solutions may comprise phosphoric acid in an amount no less than 5 vol.%, no less than 10 vol.%, no less than 15 vol.%, no less than 20 vol.%, no less than 25 vol.%, or no less than 30 vol.%.

[0025] Exemplary aqueous acid solutions comprise may further comprise boric acid (H3BO3). In various instances, exemplary aqueous acid solutions may comprise boric acid in a concentration of about 1 to about 15 grams per liter (g / L). In various instances, exemplary aqueous acid solutions may comprise boric acid in a concentration of 1 g / L to 2 g / L, 1 g / L to 3 g / L, 1 g / L to 4 g / L, 1 g / L to 5 g / L, 1 g / L to 6 g / L, 1 g / L to 7 g / L, 1 g / L to 8 g / L, 1 g / L to 9 g / L, 1 g / L to 10 g / L, 1 g / L to 11 g / L, 1 g / L to 12 g / L, 1 g / L to 13 g / L, 1 g / L to 14 g / L, 1 g / L to 15 g / L, 2 g / L to 4 g / L, 2 g / L to 6 g / L, 2 g / L to 8 g / L, 2 g / L to 10 g / L, 2 g / L to 12 g / L, 2 g / L to 14 g / L, 2 g / L to 15 g / L, 3 g / L to 6 g / L, 3 g / L to 9 g / L, 3 g / L to 12 g / L, 3 g / L to 15 g / L, 4 g / L to 8 g / L, 4 g / L to 12 g / L, 4 g / L to 15 g / L, 5 g / L to 10 g / L, 5 g / L to 15 g / L, 6 g / L to 9 g / L, 6 g / L to 12 g / L, 6 g / L to 15 g / L, 9 g / L to 12 g / L, 9 g / L to 15 g / L, or 12 g / L to 15 g / L. In various instances, exemplary aqueous acid solutions may comprise boric acid in a concentration no greater than 15 g / L, no greater than 14 g / L, no greater than 13 g / L, no greater than 12 g / L, no greater than 11 g / L, no greater than 10 g / L, no greater than 9 g / L, no greater than 8 g / L, no greater than 7 g / L, no greater than 6 g / L, no greater than 5 g / L, no greater than 4 g / L, no greater than 3 g / L, no greater than 2 g / L, or no greater than 1 g / L. In various instances, exemplary aqueous acid solutions may comprise boric acid in a concentration no less than 1 g / L, no less than 2 g / L, no less than 3 g / L, no less than 4 g / L, no less than 5 g / L, no less than 6 g / L, no less than 7 g / L, no less than 8 g / L, no less than 9 g / L, no lessAttorney Docket No. 027808-9082-W001 than 10 g / L, no less than 11 g / L, no less than 12 g / L, no less than 13 g / L, no less than 14 g / L, or no less than 15 g / L.

[0026] Exemplary aqueous acid solutions comprise water as the solvent. Accordingly, the amount of water in exemplary aqueous acid solutions may be determined by the amount of phosphoric acid and boric acid in solution. In various instances, the amount of balance water in the exemplary aqueous acid solution may be about 70 vol.% to about 95 vol.%. Other amounts are contemplated.

[0027] Exemplary aqueous acid solutions may comprise phosphoric acid, boric acid, and balance water. In some instance, the exemplary aqueous acid solution may comprise 5 to 30 vol% phosphoric acid, 1 to 15 g / L boric acid, and balance water. In some instances, the aqueous acid solution may comprise about 10 vol% phosphoric acid, 4 to 8 g / L boric acid, and balance water.III. Exemplary Systems for Anodizing a Metallic Substrate

[0023] Various electrolytic systems may be used to perform exemplary methods and techniques described herein. Exemplary electrolytic systems may comprise at least one electrode connected to a device capable of generating a voltage and discharging the voltage via the at least one electrode. Exemplary electrolytic systems may further comprise an electrolytic solution.

[0024] FIG. 1 shows a schematic diagram of an exemplary system that may be used for anodizing a metallic substrate. In the embodiment show, the system includes a cathode, an amplifier, a voltage source, an anode, and an acid electrolyte solution in a container. A metallic substrate is also schematically shown in FIG. 1. Other embodiments may include more or fewer components.

[0025] As shown, a cathode is electrically connected to an amplifier (shown as “amp”) and a portion of the cathode is submerged in the acid electrolyte solution.

[0026] The amplifier is electrically connected to a positive terminal of a voltage source (shown as “volt”) and to the cathode. An anode is electrically connected to a negative terminal of the voltage source and a portion of the anode is submerged in the acid electrolyte solution.

[0027] As shown, a metallic substrate is in contact with a portion of the cathode. Metallic substrates may be partially or fully submerged in the acid electrolyte solution. Exemplary electrolytic solutions are discussed in greater detail above.Attorney Docket No. 027808-9082-W001

[0028] The cathode may be positioned to contact the metallic substrate at various portions of the metallic substrate. As discussed in this disclosure, in some implementations, the metallic substrate is a wheel. As an example, the cathode may be positioned to contact a portion of a wheel where a tire would be positioned when the wheel is in use.IV. Exemplary Methods for Anodizing a Metal Oxide Layer on a Metallic Substrate

[0029] An example method may comprise submerging a metallic substrate into an aqueous acid solution and applying a voltage to the aqueous acid solution. Exemplary methods may also include preparing the aqueous acid solution, heating to a predetermined temperature, applying the voltage, after forming a layer of metal oxide, submerging the wheel into water, and spraying the wheel with water. As discussed in greater detail above, exemplary metallic substrates may comprise aluminum or an aluminum alloy. As discussed in greater detail above, the metallic substrate may be a wheel. Exemplary aqueous acid solutions are described in greater detail above. Other embodiments may include more or fewer operations.

[0030] The example method may include preparing the aqueous acid solution by combining phosphoric acid and water to form a solution. Phosphoric acid may be added to the water such that a resulting concentration of phosphoric acid is 5 vol% to 30 vol%. Other possible amounts of phosphoric acid are described in greater detail above. In various instances, after the phosphoric acid is added to water, or as the phosphoric acid is added to water, the resulting mixture may be mixed to dissolve the phosphoric acid in the water. In some instances, mixing may be performed mechanically with any known instrument or by sparging with clear air.

[0031] The example method may include dissolving boric acid into the solution comprising phosphoric acid and water. The mixture comprising phosphoric acid, boric acid, and water may be agitated to dissolve the boric acid. In some instances, the method may include visually monitoring the dissolution of the boric acid. In some instances, once the boric acid is substantially dissolved, the resulting aqueous acid solution may appear as a transparent liquid.

[0032] While dissolving the boric acid, or after dissolving the boric acid, exemplary methods may include heating the mixture to form a heated aqueous acid solution. In various instances, the aqueous acid solution may be heated to a temperature between about 25 °C to about 50 °C. In various instances, the aqueous acid solution may be heated to a temperature between 25 °C to 30 °C, 25 °C to 35 °C, 25 °C to 40 °C, 25 °C to 45 °C, 25 °C to 50 °C, 30 °C to 35 °C, 31 °C to 34Attorney Docket No. 027808-9082-W001°C, 30 °C to 40 °C, 30 °C to 45 °C, 30 °C to 50 °C, 35 °C to 40 °C, 35 °C to 45 °C, 35 °C to 50 °C, 40 °C to 45 °C, 40 °C to 50 °C, or 45 °C to 50 °C. In various instances, the aqueous acid solution may be heated to no greater than 50 °C, no greater than 45 °C, no greater than 40 °C, no greater than 35 °C, no greater than 30 °C, or no greater than 25 °C. In various instances, the aqueous acid solution may be heated to no less than 25 °C, no less than 30 °C, no less than 35 °C, no less than 40 °C, no less than 45 °C, or no less than 50 °C.

[0033] After generating the heated aqueous acid solution, the example method comprises submerging the metallic substrate into the heated aqueous acid solution. In some instances, the temperature of the aqueous acid solution may be between 25 °C to 50 °C while applying the voltage.

[0034] The example method comprises applying a voltage to the aqueous acid solution and the submerged metallic substrate, also referred to as anodizing. The example method may comprise positioning the cathode in contact with a surface of the metallic substrate. The example method may comprise positioning the cathode parallel to a surface of the metallic substrate.

[0035] In various instances, the applied voltage may anodize any exposed surface of the metallic substrate. In some embodiments, the applied voltage may anodize at least one outer surface of a metallic substrate, at least one inner surface of a metallic substrate, or both inner and outer surfaces of the metallic substrate.

[0036] The example method may comprise increasing the applied voltage at a rate over a first period of time followed by a holding the applied voltage at a constant, predetermined voltage for a second period of time. In various instances, the voltage may be applied with direct current (DC).

[0037] In various instances, the applied voltage may increase, starting from 0 volts, at a rate between about 0.5 volts / second and about 4 volts / second (V / sec). In various instances, the applied voltage in the first period of time may increase at a rate between 0.5 V / sec and 1.5 V / sec; 0.5 V / sec and 2 V / sec; 0.5 V / sec and 2.5 V / sec; 0.5 V / sec and 3 V / sec; 0.5 V / sec and 3.5 V / sec; 0.5 V / sec and 4 V / sec; 1 V / sec and 2 V / sec; 1 V / sec and 2.5 V / sec; 1 V / sec and 3 V / sec; 1 V / sec and 3.5 V / sec; 1 V / sec and 4 V / sec; 1.5 V / sec and 2.5 V / sec; 1.5 V / sec and 3 V / sec; 1.5 V / sec and 3.5 V / sec; 1.5 V / sec and 4 V / sec; 2 V / sec and 3 V / sec; 2 V / sec and 3.5 V / sec; 2 V / sec and 4 V / sec;2.5 V / sec and 3.5 V / sec; 2.5 V / sec and 4 V / sec; or 3 V / sec and 4 V / sec. In various instances, the applied voltage may increase at a rate no less than 0.5 V / sec; no less than 1.0 V / sec; no less than1.5 V / sec; no less than 2 V / sec; no less than 2.5 V / sec; no less than 3.0 V / sec; no less than 3.5Attorney Docket No. 027808-9082-W001V / sec; or no less than 4.0 V / sec. In various instances, the applied voltage may increase at a rate no greater than 4 V / sec; no greater than 3.5 V / sec; no greater than 3.0 V / sec; no greater than 2.5 V / sec; no greater than 2V / sec ; no greater than 1.5 V / sec; no greater than 1.0 V / sec; or no greater than 0.5 V / sec.

[0038] In various instances, the applied voltage may be increased at a rate described above for a first time period of about 5 sec to about 25 sec. In various instance, the applied voltage may be increased for a first time period of from 5 sec to 10 sec, 5 sec to 15 sec, 5 sec to 20 sec, 5 sec to 25 sec, 10 sec to 15 sec, 10 sec to 20 sec, 10 sec to 25 sec, 15 sec to 20 sec, 15 sec to 25 sec, or 20 sec to 25 sec. In various instances, the applied voltage may be increased for a first time period no greater than 25 sec, no greater than 20 sec, no greater than 15 sec, no greater than 10 sec, no greater than 5 sec. In various instances, the applied voltage may be increased for a first time period no less than 5 sec, no less than 10 sec, no less than 15 sec, no less than 20 sec, or no less than 25 sec. In some instances, increasing the applied voltage during the first time period may occur for 12-18 sec.

[0039] In various instances, the constant, predetermined voltage applied to the aqueous acid solution with the metallic substrate submerged may be about 10 volts to about 25 volts (V). In various instances, the predetermined voltage applied to the aqueous acid solution with the metallic substrate submerged may be 10 V to 15 V, 13 V to 17 V, 10 V to 20 V, 10 V to 25 V, 15 V to 20 V, 15 V to 20 V, or 20 V to 25 V. In various instances, the predetermined voltage applied to the aqueous acid solution with the metallic substrate submerged may be no greater than 25 V, no greater than 23 V, no greater than 20 V, no greater than 17 V, no greater than 15 V, no greater than 13 V, or no greater than 10 V. In various instances, the predetermined voltage applied to the aqueous acid solution with the metallic substrate submerged may be no less than 10 V, no less than 12 V, no less than 15 V, no less than 18 V, no less than 20 V, no less than 22 V, or no less than 25 V.

[0040] The example method may comprise applying the constant, predetermined voltage directly to the aqueous acid solution containing the submerged metallic substrate for a second period of time. In various instances, a constant voltage may be applied during the second period of time for about 10 sec to about 60 sec. In various instances, the constant voltage may be applied during the second period of time for 10 sec to 20 sec, 10 sec to 25 sec, 10 sec to 30 sec, 10 sec to 35 sec, 10 sec to 40 sec, 10 sec to 45 sec, 10 sec to 50 sec, 10 sec to 55 sec, 10 sec to 60 sec, 20Attorney Docket No. 027808-9082-W001 sec to 35 sec, 20 sec to 40 sec, 20 sec to 45 sec, 20 sec to 50 sec, 20 sec to 55 sec, 20 sec to 60 sec, 30 sec to 45 sec, 30 sec to 50 sec, 30 sec to 55 sec, 30 sec to 60 sec, 40 sec to 55 sec, or 40 sec to 60 sec. In various instances, the constant voltage may be applied during the second period of time for no greater than 60 sec, no greater than 50 sec, no greater than 40 sec, no greater than 30 sec, no greater than 20 sec, or no greater than 10 sec. In various instances, the constant voltage may be applied during the second period of time for no less than 10 sec, no less than 20 sec, no less than 30 sec, no less than 40 sec, no less than 50 sec, or no less than 60 sec.

[0041] The metal of the metal oxide formed by the example method may comprise aluminum, phosphorus, boron, magnesium, silicon, or manganese. The layer of metal oxide formed on a surface of the metallic substrate with the example method may further comprise aluminum, phosphorus, boron, magnesium, silicon, manganese, other metallic elements contained in the composition of the aluminum alloy, or combinations thereof.

[0042] In various instances, the method may comprise one or more operations after anodization to remove residual acid. In some instances, the method may comprise submerging the metallic substrate comprising the layer of metal oxide into distilled water (DI) after anodization. In some instances, the water in which the metallic substrate containing the layer of metal oxide is submerged is mildly agitated. In some instances, mixing may be performed mechanically with any known instrument or by sparging with clear air.

[0043] In some instances, the method may further comprise spraying the metallic substrate containing the layer of metal oxide with water after submerging the metallic substrates in water.

[0044] In some instances, the method may further comprise applying a silicone organic coating onto the metallic substrate containing the layer of metal oxide.V. Exemplary Articles of Manufacture

[0045] Exemplary methods and techniques described herein may form articles of manufacture with improved chemical, physical and cosmetic properties. An article of manufacture formed by methods and techniques described herein may comprise a metallic substrate comprising aluminum or an aluminum alloy and further comprising a metal oxide layer on a surface of the metallic substrate.

[0046] In some instances, the metallic substrate may be an automotive component. Exemplary automotive components may include wheels and doors.Attorney Docket No. 027808-9082-W001

[0047] Exemplary articles of manufacture may comprise a metallic substrate comprising aluminum or an aluminum alloy and a metal oxide layer on a surface of the metallic substrate. The metal of the metal oxide may comprise aluminum, phosphorus, boron, magnesium, silicon, manganese, other metallic elements contained in the composition of the aluminum alloy, or combinations thereof.

[0048] As an example, and without limitation, in implementations with an aluminum substrate, a metal oxide layer on the metallic substrate may comprise oxygen (O), carbon (C), aluminum (Al), phosphorous (P), and boron (B).

[0049] In various instances, the metal oxide layer on the metallic substrate may have a thickness of about 20 nanometers to about 120 nanometers (nm). In various instances, the thickness of the metal oxide layer may be 20 nm to 30 nm; 22 nm to 28 nm, 20 nm to 40 nm, 20 nm to 50 nm, 20 nm to 60 nm, 20 nm to 70 nm, 20 nm to 80 nm, 20 nm to 90 nm, 20 nm to 100 nm, 20 nm to 110 nm, 20 nm to 120 nm, 40 nm to 50 nm, 40 nm to 60 nm, 40 nm to 70 nm, 40 nm to 80 nm, 40 nm to 90 nm, 40 nm to 100 nm, 40 nm to 110 nm, 40 nm to 120 nm, 50 nm to 60 nm, 50 nm to 70 nm, 50 nm to 80 nm, 50 nm to 90 nm, 50 nm to 100 nm, 50 nm to 110 nm, 50 nm to 120 nm, 60 nm to 70 nm, 60 nm to 80 nm, 60 nm to 90 nm, 60 nm to 100 nm, 60 nm to 110 nm, 60 nm to 120 nm, 70 nm to 80 nm, 70 nm to 90 nm, 70 nm to 100 nm, 70 nm to 110 nm, 70 nm to 120 nm, 80 nm to 90 nm, 80 nm to 100 nm, 80 nm to 110 nm, 80 nm to 120 nm, 90 nm to 100 nm, 90 nm to 110 nm, 90 nm to 120 nm, 100 nm to 110 nm, 100 nm to 120 nm, or 110 nm to 120 nm. In various instances, the thickness of the metal oxide layer may be no more than 120 nm, no more than 110 nm, no more than 100 nm, no more than 90 nm, no more than 80 nm, no more than 70 nm, no more than 60 nm, no more than 50 nm, no more than 40 nm, no more than 30 nm, no more than 26 nm, or no more than 20 nm. In various instances, the thickness of the metal oxide layer may be no less than 20 nm, no less than 25 nm, no less than 30 nm, no less than 40 nm, no less than 50 nm, no less than 60 nm, no less than 70 nm, no less than 80 nm, no less than 90 nm, no less than 100 nm, no less than 110 nm, or no less than 120 nm.

[0050] In some instances, exemplary articles of manufacture may additionally comprise a silicone organic coating. In those implementations, the metal oxide layer is between the metallic substrate and the silicone organic coating. Exemplary silicone organic coatings may comprise one or more of: organic polysilazane, n-butyl acetate, acetone, and / or silicone trimethylolpropane ester.Attorney Docket No. 027808-9082-W001VI. Experimental Examples

[0048] Various experiments were conducted and the results are discussed below. Over various experiments, wheels were submerged in an electrolyte and a voltage was applied.

[0049] In a first set of experiments, an AA6099 aluminum alloy wheel was submerged in an electrolyte comprising an aqueous acid solution containing 10 vol% phosphoric acid and balance water. The electrolyte had a temperature of 32.2 ° C. A system similar to the system schematically shown in FIG. 1 was used. The aluminum wheel was anodized by exposing the first aluminum wheel to a voltage increasing from 0 V to 15 V in 15 seconds and held at 15 V for 30 seconds. An anode was positioned in the electrolyte and a cathode was connected to the aluminum wheel.

[0050] An aluminum wheel was also anodized in an aqueous acid solution containing 10% phosphoric acid, 4 g / L boric acid (HB), and balance water. The aluminum wheel was anodized using the same voltage protocol as the first aluminum wheel.

[0051] An aluminum wheel was also anodized in an aqueous acid solution containing 10% phosphoric acid, 8 g / L boric acid (HB), and balance water. The aluminum wheel was anodized using the same voltage protocol as the first aluminum wheel.

[0052] Standard Gloss Units (SGU) were measured for the aluminum wheels before and after anodization. ASTM D523 was adapted for measuring SGU at 20° angle of the experimental samples. FIG. 2 shows the gloss in SGU of the aluminum wheel after anodization.

[0053] In a second set of experiments, aluminum wheels were submerged in electrolytes comprising (1) 10 vol% phosphoric acid and (2) 10 vol% phosphoric acid and 4 g / L boric acid. Gloss was measured after anodizing and the results are shown in FIG. 3. FIG. 3 shows the gloss after anodization in SGU (left y-axis) and the percentage gloss drop (right y-axis) after anodization for the first set of experiments.

[0054] In a third set of experiments, aluminum wheels were submerged in electrolytes comprising (I) 10 vol% phosphoric acid and (2) 10 vol% phosphoric acid and 4 g / L boric acid. Gloss was measured after anodizing and the results are shown in FIG. 4. The aluminum wheels were also coated with a silicon-containing organic polymer coating and gloss was measured after anodizing and coating, also shown in FIG. 4.

[0055] FIG. 2 shows that 8 g / L of HB increased the amount of gloss to a similar level observed for 4 g / L HB. FIG. 2 and FIG. 3 show that the aqueous acid solution containing 4 g / L HB exhibited an enhanced gloss compared to electrolytes without HB. The change in the gloss between theAttorney Docket No. 027808-9082-W001 aluminum wheel before anodization and after anodization were calculated as percent (%) gloss drop. The aqueous acid solution containing 10% phosphoric acid and 4 g / L HB exhibited a reduced amount of % gloss drop as compared to the aqueous acid solution containing only 10% phosphoric acid. Additionally, FIG. 4 shows the trends in gloss and % gloss drop persisted in the presence of the organic polymer coating.

[0056] FIG. 5 is a graph showing field emission scanning auger microprobe (FESAM) analysis of an exemplary film (a metal oxide layer). The graph in FIG. 5 shows the concentration in atomic percent (at%) of oxygen (O), carbon (C), aluminum (Al), phosphorous (P), and boron (B) as sputtering is performed over a 4 minute time period. Measurement data were obtained using a Phi 710 Scanning Auger Nanoprobe, available from Physica Electronics (Chanhassen, MN). Broadly, FESAM sputtering analysis provides semi-quantitative detection of elements present on a surface of a sample. A sputtering rate of 9.6 nm / minute was used for the analysis.

[0057] The metal oxide layer evaluated by FESAM was generated as follows: an AA6099 aluminum alloy wheel was submerged in an electrolyte comprising an aqueous acid solution containing 10 vol% phosphoric acid, 4 g / L boric acid, and balance water. The electrolyte had a temperature of 32.2 ° C. A system similar to the system schematically shown in FIG. 1 was used, and an anode was positioned in the electrolyte and a cathode was connected to the aluminum wheel. The aluminum wheel was anodized by exposing the aluminum wheel to a voltage increasing from 0 V to 15 V in 15 seconds and held at 15 V for 30 seconds.

[0058] As shown in FIG. 5, boron (B) and phosphorous (P) are integral components of the oxide layer. As shown, the metal oxide layer has a starting amount of about 40 atomic percent (at%) oxygen (O), and about 2.6 minutes elapse before the FESAM detects 20 at% oxygen, or half of the initial amount of oxygen (O). Using the amount of time before the oxygen content drops by half, at a sputtering rate of 9.6 nm / minute, the metal oxide layer thickness is estimated to be 25.1 nm.

[0059] It is understood that the foregoing detailed description and accompanying examples are merely illustrative and are not to be taken as limitations upon the scope of the disclosure. Various changes and modifications to the disclosed embodiments will be apparent to those skilled in the art. Such changes and modifications, including without limitation those relating to the chemical structures, substituents, derivatives, intermediates, syntheses, compositions, formulations, pH andAttorney Docket No. 027808-9082-W001 temperature adjustments, separation, recovery, or methods of use, may be made without departing from the spirit and scope of the disclosure.EMBODIMENTS

[0060] For reasons of completeness, the following embodiments are provided.Embodiment 1. A method for anodizing a wheel, the method comprising: submerging the wheel into an aqueous acid solution, wherein the aqueous acid solution comprises phosphoric acid, boric acid, and water; and applying a voltage to the aqueous acid solution, thereby forming a layer of metal oxide on a surface of the wheel.Embodiment 2. The method according to Embodiment 1, wherein the wheel comprises aluminum or an aluminum alloy; and wherein the aluminum alloy comprises aluminum, magnesium, silicon, copper, manganese, iron, chromium, titanium, zinc, or a combination thereof.Embodiment 3. The method according to Embodiment 1 or Embodiment 2, wherein the aqueous acid solution comprises phosphoric acid at a concentration between 0.73 M and 4.4 M, about 3 grams per liter to about 8 grams per liter boric acid, and balance water.Embodiment 4. The method according to any one of Embodiments 1-3, further comprising: preparing the aqueous acid solution by combining the phosphoric acid and water; and after combining the phosphoric acid and water, dissolving boric acid followed by mixing, wherein the aqueous acid solution comprises phosphoric acid at a concentration between 1.1 M and 2.25 M.Embodiment 5. The method according to Embodiment 1-4, further comprising heating the aqueous acid solution to a temperature between 25 °C and 50 °C before applying the voltage to the aqueous acid solution.Attorney Docket No. 027808-9082-W001Embodiment 6. The method according to any one of Embodiments 1-5, wherein the voltage is 12 volts to 20 volts (V) applied with direct current (DC).Embodiment 7. The method according to any one of Embodiments 1-6, wherein the voltage is applied for 12 seconds to 45 seconds.Embodiment 8. The method according to any one of Embodiments 1-7, wherein the voltage is increased at a rate between 0.5 V / second to 4 V / second before reaching a predetermined voltage.Embodiment 9. The method according to Embodiment 8, wherein the predetermined voltage is held for a period of time of 10 seconds to 60 seconds.Embodiment 10. The method according to any one of Embodiments 1-9, wherein the voltage is applied by at least one electrode to an outer and / or inner metallic surface of the wheel.Embodiment 11. The method according to any one of Embodiments 1-10, wherein the layer of metal oxide comprises aluminum, phosphorus, boron, magnesium, silicon, manganese, other metallic elements in a composition of an aluminum alloy, or a combination thereof.Embodiment 12. The method according to any one of Embodiments 1-11, wherein the layer of metal oxide has a thickness of 20 nanometers to 120 nanometers.Embodiment 13. The method according to any one of Embodiments 1-12, further comprising: after forming the layer of metal oxide, submerging the wheel into water.Embodiment 14. The method according to Embodiment 13, further comprising agitating the water during submerging.Embodiment 15. The method according to Embodiment 13, further comprising: after submerging the wheel into water, spraying the wheel with water.Attorney Docket No. 027808-9082-W001Embodiment 16. An article, comprising: a metallic substrate comprising aluminum or an aluminum alloy; and a metal oxide layer on a surface of the metallic substrate, wherein the metal oxide layer has a thickness of 20 nanometers to 120 nanometers.Embodiment 17. The article according to Embodiment 16, further comprising a silicone organic coating, where the metal oxide layer is disposed between the metallic substrate and the silicone organic coating.Embodiment 18. The article according to Embodiment 16 or Embodiment 17, wherein the metal oxide layer comprises aluminum, phosphorus, boron, magnesium, silicon, manganese, or a combination thereof.Embodiment 19. The article according to any one of Embodiments 16-18, wherein the metal oxide layer consists essentially of oxygen (O), carbon (C), aluminum (Al), phosphorous (P), and boron (B).Embodiment 20. The article according to any one of Embodiments 16-19, wherein the article is a wheel.

Claims

Attorney Docket No. 027808-9082-W001CLAIMS1. A method for anodizing a wheel, the method comprising: submerging the wheel into an aqueous acid solution, wherein the aqueous acid solution comprises phosphoric acid, boric acid, and water; and applying a voltage to the aqueous acid solution, thereby forming a layer of metal oxide on a surface of the wheel.

2. The method according to claim 1, wherein the wheel comprises aluminum or an aluminum alloy; and wherein the aluminum alloy comprises aluminum, magnesium, silicon, copper, manganese, iron, chromium, titanium, zinc, or a combination thereof.

3. The method according to claim 2, wherein the aqueous acid solution comprises phosphoric acid at a concentration between 0.73 M and 4.4 M, 3 grams per liter to 8 grams per liter boric acid, and balance water.

4. The method according to claim 3, further comprising: preparing the aqueous acid solution by combining the phosphoric acid and water; and after combining the phosphoric acid and water, dissolving boric acid followed by mixing, wherein the aqueous acid solution comprises phosphoric acid at a concentration between 1.1 M and 2.25 M.

5. The method according to claim 4, further comprising heating the aqueous acid solution to a temperature between 25 °C and 50 °C before applying the voltage to the aqueous acid solution.

6. The method according to claim 1, wherein the voltage is 12 volts to 20 volts (V) applied with direct current (DC).Attorney Docket No. 027808-9082-W0017. The method according to claim 6, wherein the voltage is applied for 12 seconds to 45 seconds.

8. The method according to claim 7, wherein the voltage is increased at a rate between 0.5 V / second to 4 V / second before reaching a predetermined voltage.

9. The method according to claim 8, wherein the predetermined voltage is held for a period of time of 10 seconds to 60 seconds.

10. The method according to claim 9, wherein the voltage is applied by at least one electrode to an outer and / or inner metallic surface of the wheel.

11. The method according to claim 10, wherein the layer of metal oxide comprises aluminum, phosphorus, boron, magnesium, silicon, manganese, other metallic elements in a composition of an aluminum alloy, or a combination thereof.

12. The method according to claim 11, wherein the layer of metal oxide has a thickness of 20 nanometers to 120 nanometers.

13. The method according to claim 12, further comprising: after forming the layer of metal oxide, submerging the wheel into water.

14. The method according to claim 13, further comprising agitating the water during submerging.

15. The method according to claim 13, further comprising: after submerging the wheel into water, spraying the wheel with water.

16. An article, comprising: a metallic substrate comprising aluminum or an aluminum alloy; andAttorney Docket No. 027808-9082-W001 a metal oxide layer on a surface of the metallic substrate, wherein the metal oxide layer has a thickness of 20 nanometers to 120 nanometers.

17. The article according to claim 16, further comprising a silicone organic coating, where the metal oxide layer is disposed between the metallic substrate and the silicone organic coating.

18. The article according to claim 17, wherein the metal oxide layer comprises aluminum, phosphorus, boron, magnesium, silicon, manganese, or a combination thereof.

19. The article according to claim 17, wherein the metal oxide layer consists essentially of oxygen (O), carbon (C), aluminum (Al), phosphorous (P), and boron (B).

20. The article according to claim 19, wherein the article is a wheel.

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