THERMALLY MODIFIED OXIDE BASED PRETREATMENTS FOR METALS AND METHODS OF MAKING THE SAME

- Novelis Inc.

Provided herein are corrosion resistant metal substrates and methods for producing the same by thermal modification. The disclosure provides methods for producing corrosion resistant substrates by producing a pretreatment film on a surface of a metal substrate and heating the pretreated metal substrate. In particular, the metal substrate and/or the pretreated metal substrate of these methods is in an F temper, a T4 temper, or a T6 temper.

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Description
CROSS-REFERENCE TO RELATED APPLICATION

The present application claims priority to and filing benefit of U.S. provisional patent application Ser. No. 63/015,056, filed Apr. 24, 2020, which is incorporated herein by reference in its entirety.

FIELD

The present disclosure generally relates to processing of metal substrates, such as aluminum alloys. More specifically, the present disclosure relates to thermal modification of pretreated metal substrates.

BACKGROUND

Certain metal products, such as aluminum alloys, can benefit from pretreatment, e.g., the application or production of a pretreatment film on a surface of the metal product. These benefits include bond durability, color stability, ease of maintenance, aesthetics, health and safety, and low cost. However, it is difficult to produce aluminum alloy coils having a pretreatment film that meets flexibility, durability and/or surface characteristics requirements for downstream processing, including joining of aluminum alloy products. Furthermore, conventional methods require limiting the exposure of the pretreated metal to high temperatures, e.g., to avoid loss of the above-described benefits. This limits the types of products, e.g., the tempers of the aluminum alloys, that may be pretreated.

SUMMARY

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 Detailed 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.

In one aspect, the present disclosure describes a method of making a corrosion resistant substrate, the method comprising producing a pretreatment film on a surface of a metal substrate to provide a pretreated metal substrate; and heating the pretreated metal substrate at a first temperature to provide the corrosion resistant substrate, wherein the first temperature is greater than 300° C.; and wherein the metal substrate and/or the pretreated metal substrate is in an F temper, a T4 temper, or a T6 temper. In some cases, the metal substrate comprises an aluminum alloy (e.g., a 5xxx series aluminum alloy, a 6xxx series aluminum alloy, or a 7xxx series aluminum alloy). In some cases, the corrosion resistant substrate is in a T6 temper. In some cases, the pretreatment film comprises an oxide layer. In some cases, the oxide layer comprises an aluminum oxide, a silicon oxide, a titanium oxide, a chromium oxide, a manganese oxide, a nickel oxide, a yttrium oxide, a zirconium oxide, a molybdenum oxide, or combinations thereof. In some cases, producing the pretreatment film comprises applying an inorganic pretreatment composition to the surface of the metal substrate. In some cases, producing the pretreatment film comprises anodizing the surface of the metal substrate. In some cases, producing the pretreatment film comprises flame hydrolyzing the surface of the metal substrate. In some cases, the first temperature is from 300° C. to 550° C. In some cases, the heating comprises heating the pretreated metal substrate at the first temperature for less than 30 minutes. Optionally, the heating further comprises heating the pretreated metal substrate at a second temperature. In some cases, the second temperature is lower than the first temperature. In some cases, the second temperature is from 75° C. to 250° C. In some cases, the heating comprises heating the pretreated metal substrate at the second temperature from 1 hour to 48 hours. In some cases, the metal substrate is a continuous coil.

In another aspect, the present disclosure describes a corrosion resistant coil comprising an aluminum alloy continuous coil, wherein a surface of the aluminum alloy continuous coil comprises an inorganic pretreatment film, and wherein the aluminum alloy continuous coil is in an F temper, a T4 temper, or a T6 temper. In some cases, the aluminum alloy continuous coil comprises a 5xxx series aluminum alloy, a 6xxx series aluminum alloy, or a 7xxx series aluminum alloy. In some cases, the inorganic pretreatment film comprises an oxide layer. In some cases, the oxide layer comprises an aluminum oxide, a silicon oxide, a titanium oxide, a chromium oxide, a manganese oxide, a nickel oxide, a yttrium oxide, a zirconium oxide, a molybdenum oxide, or combinations thereof.

In another aspect, the present disclosure describes a method of making a corrosion resistant substrate, the method comprising producing a pretreatment film on a surface of a metal substrate to provide a pretreated metal substrate; and heating the pretreated metal substrate at a first temperature to provide the corrosion resistant substrate, wherein the metal substrate and/or the pretreated metal substrate is in an F temper, and wherein the corrosion resistant substrate is in a T5 temper, a T6 temper, a T61 temper, a T7 temper, T8x temper, or a T9 temper.

BRIEF DESCRIPTION OF THE DRAWINGS

The disclosure is described in detail below with reference to the appended drawings.

FIG. 1 illustrate results from glow discharge optical emission spectrometry (GDOES) analysis of corrosion resistant substrates according to certain aspects of the present disclosure.

 DETAILED DESCRIPTION

Described herein are methods for making a corrosion resistant metal substrate, such as a corrosion resistant aluminum alloy substrate. The corrosion resistant substrates described herein can be used, for example, to produce corrosion resistant products that have superior surface qualities and minimized surface defects as compared to products prepared from metal substrates that have not been processed according to the present disclosure.

Various pretreatments are often employed in conventional processing of metal substrates, such as aluminum alloys. Some conventional processes produce a pretreatment film on one or more surfaces of the metal substrate by chemical or electrolytic modification. The pretreatment film may alter properties of the metal substrate, such as bond durability, adhesion, or corrosion rate. In conventional methods, the metal substrates are not subjected to thermal modification after pretreatment. In particular, conventional methods avoid exposing pretreatment films on surfaces of metal substrates to high temperatures (e.g., temperatures greater than 400° C.). For example, conventional methods dry pretreated surfaces at temperatures less than 100° C. This is due to the commonly held belief by those of ordinary skill in the art that exposure to high temperatures would degrade the pretreatment film, e.g., by burning the pretreatment film, or otherwise reducing the effectiveness of the pretreatment film. Furthermore, because of the commonly held belief that exposure to high temperatures provides no advantage, thermal modification of metal substrates after pretreatment was considered to be an unnecessary additional cost to be avoided.

Despite the conventional belief urging otherwise, the methods described herein include intentionally exposing pretreatment films to high temperatures. The present disclosure provides methods of making a corrosion resistant metal substrate by producing a pretreatment film on a surface of a metal substrate and heating the pretreated metal substrate to a temperature greater than 400° C. The exposure of pretreatment films to high temperatures (e.g., greater than 400° C.) according to the methods described herein do not degrade or negatively impact the pretreatment film. On the contrary, the high temperatures improve (e.g., enhance) the properties of the pretreatment film. Heating the pretreated metal substrate according to the present disclosure dries and/or densifies the pretreatment film, improving the bond durability, adhesion, and/or corrosion resistance imparted by the pretreatment film.

Thus, the corrosion resistant substrates produced by the methods described herein exhibit excellent physical properties, such as bond durability. Furthermore, the processes described herein are suitable for coil-to-coil lines as well as batch processing.

Definitions and Descriptions

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.

In this description, reference is made to alloys identified by aluminum industry designations, such as “series” 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.

As used herein, a plate generally has a thickness of greater than about 15 mm. For example, a plate may refer to an aluminum product having a thickness of greater than 15 mm, greater than 20 mm, greater than 25 mm, greater than 30 mm, greater than 35 mm, greater than 40 mm, greater than 45 mm, greater than 50 mm, or greater than 100 mm.

As used herein, a shate (also referred to as a sheet plate) generally has a thickness of from about 4 mm to about 15 mm. For example, a shate may have a thickness of 4 mm, 5 mm, 6 mm, 7 mm, 8 mm, 9 mm, 10 mm, 11 mm, 12 mm, 13 mm, 14 mm, or 15 mm.

As used herein, a sheet generally refers to an aluminum product having a thickness of less than about 4 mm. For example, a sheet may have a thickness of less than 4 mm, less than 3 mm, less than 2 mm, less than 1 mm, less than 0.5 mm, less than 0.3 mm, or less than 0.1 mm.

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.

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.

As used herein, a “coil-to-coil” line or “coil-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. An alloy processed is such a processing method is referred to herein as a “continuous coil” or an “aluminum alloy continuous coil.”

Reference is made in this 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.

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

As used herein, the modifier “about” is intended to include the described term without the word “about” (e.g., “about 10” is intended to include “10”).

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.

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.

Metal Substrate

As noted, the present disclosure provides methods for making a corrosion resistant metal substrate. More specifically, the methods described herein produce a pretreatment film on the surface of a metal substrate. The composition of the metal substrate on which the pretreatment film is formed is not particularly limited. The pretreatment film 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 series aluminum alloys, 5xxx series aluminum alloys, 6xxx series aluminum alloys, 7xxx series aluminum alloys, and 8xxx series aluminum alloys.

By way of non-limiting example, exemplary 1xxx series aluminum alloys for use as the metal substrate can include AA1100, AA1100A, AA1200, AA1200A, AA1300, AA1110, AA1120, AA1230, AA1230A, AA1235, AA1435, AA1145, AA1345, AA1445, AA1150, AA1350, AA1350A, AA1450, AA1370, AA1275, AA1185, AA1285, AA1385, AA1188, AA1190, AA1290, AA1193, AA1198, or AA1199. 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).

Non-limiting exemplary 2xxx series aluminum alloys for use as the metal substrate can include AA2001, AA2002, AA2004, AA2005, AA2006, AA2007, AA2007A, AA2007B, AA2008, AA2009, AA2010, AA2011, AA2011A, AA2111, AA2111A, AA2111B, AA2012, AA2013, AA2014, AA2014A, AA2214, AA2015, AA2016, AA2017, AA2017A, AA2117, AA2018, AA2218, AA2618, AA2618A, AA2219, AA2319, AA2419, AA2519, AA2021, AA2022, AA2023, AA2024, AA2024A, AA2124, AA2224, AA2224A, AA2324, AA2424, AA2524, AA2624, AA2724, AA2824, AA2025, AA2026, AA2027, AA2028, AA2028A, AA2028B, AA2028C, AA2029, AA2030, AA2031, AA2032, AA2034, AA2036, AA2037, AA2038, AA2039, AA2139, AA2040, AA2041, AA2044, AA2045, AA2050, AA2055, AA2056, AA2060, AA2065, AA2070, AA2076, AA2090, AA2091, AA2094, AA2095, AA2195, AA2295, AA2196, AA2296, AA2097, AA2197, AA2297, AA2397, AA2098, AA2198, AA2099, or AA2199.

Non-limiting exemplary 3xxx series aluminum alloys for use as the metal substrate can include AA3002, AA3102, AA3003, AA3103, AA3103A, AA3103B, AA3203, AA3403, AA3004, AA3004A, AA3104, AA3204, AA3304, AA3005, AA3005A, AA3105, AA3105A, AA3105B, AA3007, AA3107, AA3207, AA3207A, AA3307, AA3009, AA3010, AA3110, AA3011, AA3012, AA3012A, AA3013, AA3014, AA3015, AA3016, AA3017, AA3019, AA3020, AA3021, AA3025, AA3026, AA3030, AA3130, or AA3065.

Non-limiting exemplary 4xxx series aluminum alloys for use as the metal substrate can include AA4004, AA4104, AA4006, AA4007, AA4008, AA4009, AA4010, AA4013, AA4014, AA4015, AA4015A, AA4115, AA4016, AA4017, AA4018, AA4019, AA4020, AA4021, AA4026, AA4032, AA4043, AA4043A, AA4143, AA4343, AA4643, AA4943, AA4044, AA4045, AA4145, AA4145A, AA4046, AA4047, AA4047A, or AA4147.

Non-limiting exemplary 5xxx series aluminum alloys for use as the metal substrate can include AA5182, AA5183, AA5005, AA5005A, AA5205, AA5305, AA5505, AA5605, AA5006, AA5106, AA5010, AA5110, AA5110A, AA5210, AA5310, AA5016, AA5017, AA5018, AA5018A, AA5019, AA5019A, AA5119, AA5119A, AA5021, AA5022, AA5023, AA5024, AA5026, AA5027, AA5028, AA5040, AA5140, AA5041, AA5042, AA5043, AA5049, AA5149, AA5249, AA5349, AA5449, AA5449A, AA5050, AA5050A, AA5050C, AA5150, AA5051, AA5051A, AA5151, AA5251, AA5251A, AA5351, AA5451, AA5052, AA5252, AA5352, AA5154, AA5154A, AA5154B, AA5154C, AA5254, AA5354, AA5454, AA5554, AA5654, AA5654A, AA5754, AA5854, AA5954, AA5056, AA5356, AA5356A, AA5456, AA5456A, AA5456B, AA5556, AA5556A, AA5556B, AA5556C, AA5257, AA5457, AA5557, AA5657, AA5058, AA5059, AA5070, AA5180, AA5180A, AA5082, AA5182, AA5083, AA5183, AA5183A, AA5283, AA5283A, AA5283B, AA5383, AA5483, AA5086, AA5186, AA5087, AA5187, or AA5088.

Non-limiting exemplary 6xxx series aluminum alloys for use as the metal substrate can include AA6101, AA6101A, AA6101B, AA6201, AA6201A, AA6401, AA6501, AA6002, AA6003, AA6103, AA6005, AA6005A, AA6005B, AA6005C, AA6105, AA6205, AA6305, AA6006, AA6106, AA6206, AA6306, AA6008, AA6009, AA6010, AA6110, AA6110A, AA6011, AA6111, AA6012, AA6012A, AA6013, AA6113, AA6014, AA6015, AA6016, AA6016A, AA6116, AA6018, AA6019, AA6020, AA6021, AA6022, AA6023, AA6024, AA6025, AA6026, AA6027, AA6028, AA6031, AA6032, AA6033, AA6040, AA6041, AA6042, AA6043, AA6151, AA6351, AA6351A, AA6451, AA6951, AA6053, AA6055, AA6056, AA6156, AA6060, AA6160, AA6260, AA6360, AA6460, AA6460B, AA6560, AA6660, AA6061, AA6061A, AA6261, AA6361, AA6162, AA6262, AA6262A, AA6063, AA6063A, AA6463, AA6463A, AA6763, A6963, AA6064, AA6064A, AA6065, AA6066, AA6068, AA6069, AA6070, AA6081, AA6181, AA6181A, AA6082, AA6082A, AA6182, AA6091, or AA6092.

Non-limiting exemplary 7xxx series aluminum alloys for use as the metal substrate can include AA7011, AA7019, AA7020, AA7021, AA7039, AA7072, AA7075, AA7085, AA7108, AA7108A, AA7015, AA7017, AA7018, AA7019A, AA7024, AA7025, AA7028, AA7030, AA7031, AA7033, AA7035, AA7035A, AA7046, AA7046A, AA7003, AA7004, AA7005, AA7009, AA7010, AA7011, AA7012, AA7014, AA7016, AA7116, AA7122, AA7023, AA7026, AA7029, AA7129, AA7229, AA7032, AA7033, AA7034, AA7036, AA7136, AA7037, AA7040, AA7140, AA7041, AA7049, AA7049A, AA7149, AA7204, AA7249, AA7349, AA7449, AA7050, AA7050A, AA7150, AA7250, AA7055, AA7155, AA7255, AA7056, AA7060, AA7064, AA7065, AA7068, AA7168, AA7175, AA7475, AA7076, AA7178, AA7278, AA7278A, AA7081, AA7181, AA7185, AA7090, AA7093, AA7095, or AA7099.

Non-limiting exemplary 8xxx series aluminum alloys for use as the metal substrate cane include AA8005, AA8006, AA8007, AA8008, AA8010, AA8011, AA8011A, AA8111, AA8211, AA8112, AA8014, AA8015, AA8016, AA8017, AA8018, AA8019, AA8021, AA8021A, AA8021B, AA8022, AA8023, AA8024, AA8025, AA8026, AA8030, AA8130, AA8040, AA8050, AA8150, AA8076, AA8076A, AA8176, AA8077, AA8177, AA8079, AA8090, AA8091, or AA8093.

While aluminum alloy products are described throughout the disclosure, the methods and products apply to any metal substrate. In some embodiments, the metal 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 substrate is a metal coil, a metal strip, a metal plate, a metal shate, a metal sheet, a metal billet, a metal ingot, or other metal article.

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.

The metal substrate can be prepared from an alloy of any temper. In some embodiments, the metal substrate is an alloy in an F temper, a T4 temper, or a T6 temper. As discussed below, the temper of the metal substrate may be altered by the thermal modification described herein. In one embodiment of the method, for example, a metal substrate is provided in an F temper, a pretreatment film is produced on a surface of the metal substrate, and the pretreated metal substrate is heated such that the final corrosion resistant substrate is in a T6 temper without compromising the pretreatment film.

Pretreatment

The methods described herein include producing a pretreatment film on a surface of the metal substrate to provide a pretreated metal substrate. The pretreatment films described herein improve properties, such as adhesion and/or corrosion resistance, of the metal substrates on the surfaces of which the pretreatment films are produced.

The method of producing the pretreatment film on a surface of the metal substrate is not particularly limited, and any suitable method known in the art may be used. In some embodiments, producing the pretreatment film may comprise applying a pretreatment composition (e.g., an inorganic pretreatment composition) to the surface of the metal substrate. In some cases, for example, the pretreatment composition (e.g., an inorganic pretreatment composition) may be sprayed on a surface of the metal substrate. In some cases, the metal substrate may be submerged in a pretreatment composition (e.g., an inorganic pretreatment composition). The pretreatment composition (e.g., an inorganic pretreatment composition) may be specially formulated to produce a pretreatment film on the surface of the metal substrate. For example, the pretreatment composition may include chromium, molybdenum, titanium, zirconium, manganese, or combinations thereof.

In some embodiments, producing the pretreatment film may comprise anodizing a surface of the metal substrate. Anodizing may comprise, for example, contacting the surface of the metal substrate with an electrolyte solution and applying an electric current (e.g., alternating current (AC) power and/or direct current (DC)) to the metal substrate. In some cases, anodizing the metal substrates produces a pretreated metal substrate having a thin pretreatment film, which may comprise an oxide layer. Suitable methods for anodizing are described in U.S. Pub. No. 2020/0082972, which is incorporated herein by reference.

In some embodiments, producing the pretreatment film may comprise a pyrogenic process. For example, the pretreatment film may be produced by flame pyrolysis deposition. Flame pyrolysis deposition may comprise burning (e.g., combusting) a metallic product to produce a deposit on the surface of the metal substrate. The composition of the deposit will vary with the gas mixture and/or metallic compound, which may be specially formulated for the flame pyrolysis deposition. In some cases, the deposit, which may comprise an oxide, forms a pretreatment film.

The composition or structure of the pretreatment film on the pretreated metal substrate is not particularly limited, and any pretreatment film known in the art may be produced or used. Pretreatment films known in the art may be classified as organic pretreatment films, inorganic pretreatment films, and combination pretreatment films. Organic pretreatment films comprise an organic compound (i.e., a carbon-containing compound), such as organic polymers. Inorganic pretreatment films comprise an inorganic compound (i.e., a non-carbon containing compound), such as metal ion analogues and metallic coordination complexes. Combination pretreatment films comprise both an organic compound and an inorganic compound or an organic-inorganic compound that includes both organic and inorganic moieties.

In some embodiments, the pretreatment film produced in the disclosed methods is an organic pretreatment film. Preferably, however, the pretreatment film is an inorganic pretreatment film or a combination pretreatment film. As described herein, thermal modification (discussed below) of metal substrates that have been pretreated with inorganic and/or combination pretreatment films surprisingly improves properties (e.g., adhesion, corrosion resistance) of the metal substrates. On the contrary, the present inventors have found that thermal modification of metal substrates that have been pretreated with organic pretreatment films may not improve properties (e.g., may not improve properties to the same degree). In some cases, the thermal modification of metal substrates having an organic pretreatment film may even degrade properties of the substrate. It is theorized that organic compounds present in conventional organic pretreatment films (e.g., organic polymers) may undergo undesirable chemical reactions (e.g., combustion) when subjected to the thermal modification described herein. Thus, in some embodiments of the methods, the pretreatment film is not an organic pretreatment film (i.e., a pretreatment film including an organic compound only).

In some cases, producing the pretreatment film on a surface of the metal substrate comprises creating an oxide layer on the surface. Said another way, the pretreatment film may comprise an oxide layer. For example, the pretreatment film may comprise an inorganic oxide layer. The oxide layer comprises one or more oxides, such as metallic oxides.

The composition of the oxide layer is not particularly limited, and any suitable oxide layer known in the art may be used. The oxide layer may comprise, for example, an aluminum oxide (e.g., Al2O, AlO, and/or Al2O3), a silicon oxide (e.g., SiO2 and/or SiO), a titanium oxide (e.g., Ti2O, TiO, Ti2O3, and/or TiO2), a chromium oxide (e.g., CrO, Cr2O3, CrO2, and/or CrO5), a manganese oxide (e.g., MnO, Mn3O4, Mn2O3, MnO2, MnO3, and/or Mn2O7), a nickel oxide (e.g., NiO and/or Ni2O3), a yttrium oxide (e.g., Y2O3), a zirconium oxide (e.g., ZrO2), a molybdenum oxide (e.g., MoO2 and/or MoO3), or combinations thereof.

In some embodiments, the pretreatment film comprises an oxide layer of aluminum oxide. In some embodiments, the pretreatment film comprises an oxide layer of silicon oxide. In some embodiments, the pretreatment film comprises a combination of oxides. For example, the pretreatment film may comprise on oxide layer of titanium oxide and zirconium oxide.

Generally, the pretreatment film comprises a thin layer on a portion (e.g., at least a portion) of a surface of the metal substrate. In some cases, the pretreatment film may be produced on one surface of the metal substrate. In some cases, the pretreatment film may be produced on one or more surfaces of the metal substrate, e.g., two surfaces. In some cases, the pretreatment film is produced on all surfaces of the metal substrate.

The thickness of the pretreatment film may vary. As noted, the pretreatment film is generally a thin layer. The thickness of the pretreatment film can range from about 1 nm to about 1000 nm. In some cases, the pretreatment film 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 pretreatment film 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 in thickness. In some examples, the pretreatment film can be about 1 nm, about 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 200 nm, about 250 nm, about 300 nm, about 400 nm, about 500 nm, about 600, about 700 nm, about 750 nm, about 800 nm, about 850 nm, about 900 nm, about 950 nm, or about 1000 nm in thickness, or anywhere in between.

In some cases, the pretreatment film on the pretreated metal substrate may be composed of multiple layers. In particular, certain methods of producing the pretreatment film may produce distinct layers within the pretreatment film. For example, anodizing the metal substrate may produce a pretreatment film including a barrier layer (e.g., composed of aluminum oxide, such as nonporous aluminum oxide) and a filament layer (e.g., composed of aluminum oxide, such porous aluminum oxide). The characteristics of either layer may be controlled by the method of producing the pretreatment film (e.g., the anodizing parameters or conditions).

The temper of the substrate is generally not affected (e.g., altered) by producing the pretreatment film. That is, the pretreated metal substrate generally is in the same temper as the metal substrate before pretreatment. In some embodiments, the pretreated metal substrate is an alloy in an F temper, a T4 temper, or a T6 temper. As discussed below, the temper of the metal substrate may be altered by the thermal modification described herein. In one embodiment, for example, the pretreated metal substrate is in F temper, and the thermal modification of the pretreated metal substrate produces a substrate in a T6 temper.

Thermal Modification

The methods described herein include heating the pretreated metal substrate to provide the corrosion resistant substrate. As noted above, conventional methods of pretreating metal substrates avoid exposing the metal substrate to high temperatures (e.g., temperatures greater than 400° C.) after a pretreatment film has been produced. It was believed by those of ordinary skill in the art that exposure to high temperatures would degrade the pretreatment film or otherwise reduce the effectiveness of the pretreatment film. On the contrary, heating a pretreated metal substrate according to the methods described herein enhances the pretreatment film.

The thermal modification of the present disclosure includes heating the pretreated metal substrate at a first temperature, which is generally a high temperature relative to conventional methods. In some embodiments, the first temperature is from 300° C. to 550° C., e.g., from 300° C. to 540° C., from 300° C. to 530° C., from 300° C. to 520° C., from 300° C. to 510° C., from 300° C. to 500° C., from 325° C. to 550° C., from 325° C. to 540° C., from 325° C. to 530° C., from 325° C. to 520° C., from 325° C. to 510° C., from 325° C. to 500° C., from 350° C. to 550° C., from 350° C. to 540° C., from 350° C. to 530° C., from 350° C. to 520° C., from 350° C. to 510° C., from 350° C. to 500° C., from 375° C. to 550° C., from 375° C. to 540° C., from 375° C. to 530° C., from 375° C. to 520° C., from 375° C. to 510° C., from 375° C. to 500° C., from 400° C. to 550° C., from 400° C. to 540° C., from 400° C. to 530° C., from 400° C. to 520° C., from 400° C. to 510° C., from 400° C. to 500° C., from 425° C. to 550° C., from 425° C. to 540° C., from 425° C. to 530° C., from 425° C. to 520° C., from 425° C. to 510° C., from 425° C. to 500° C., from 450° C. to 550° C., from 450° C. to 540° C., from 450° C. to 530° C., from 450° C. to 520° C., from 450° C. to 510° C., or from 450° C. to 500° C.

In terms of upper limits, the first temperature may be less than 550° C., e.g., less than 540° C., less than 530° C., less than 520° C., less than 510° C., or less than 500° C. In terms of lower limits, the first temperature may be greater than 300° C., e.g., greater than 325° C., greater than 350° C., greater than 375° C., greater than 400° C., greater than 425° C., or greater than 450° C.

In some cases, the first temperature may be about 375° C., about 385° C., about 395° C., about 400° C., about 405° C., about 410° C., about 415° C., about 420° C., about 425° C., about 430° C., about 435° C., about 440° C., about 445° C., about 450° C., about 455° C., about 460° C., about 465° C., about 466° C., about 467° C., about 468° C., about 469° C., 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., about 495° C., about 496° C., about 497° C., about 498° C., about 499° C., about 500° C., about 510° C., about 520° C., about 525° C., about 530° C., about 540° C., or about 550° C., or any temperature therebetween.

The thermal modification of the described methods may include prolonged exposure to high temperatures, e.g., the first temperature. Prolonged exposure to high temperatures may enhance the pretreatment film, e.g., by (further) drying and/or densifying the pretreatment film. Thus, in some embodiments, the pretreated metal substrate may be heated at the first temperature for a period of time.

In some embodiments, the pretreated metal substrate is heated at the first temperature for a period of time from 10 seconds to 30 minutes, e.g., from 10 seconds to 25 minutes, from 10 seconds to 20 minutes, from 10 seconds to 15 minutes, from 10 seconds to 10 minutes, from 15 seconds to 30 minutes, from 15 seconds to 25 minutes, from 15 seconds to 20 minutes, from 15 seconds to 15 minutes, from 15 seconds to 10 minutes, from 30 seconds to 30 minutes, from 30 seconds to 25 minutes, from 30 seconds to 20 minutes, from 30 seconds to 15 minutes, from 30 seconds to 10 minutes, from 60 seconds to 30 minutes, from 60 seconds to 25 minutes, from 60 seconds to 20 minutes, from 60 seconds to 15 minutes, from 60 seconds to 10 minutes, from 75 seconds to 30 minutes, from 75 seconds to 25 minutes, from 75 seconds to 20 minutes, from 75 seconds to 15 minutes, from 75 seconds to 10 minutes, from 90 seconds to 30 minutes, from 90 seconds to 25 minutes, from 90 seconds to 20 minutes, from 90 seconds to 15 minutes, or from 90 seconds to 10 minutes.

In terms of upper limits, the pretreated metal substrate may be heated at the first temperature for less than 30 minutes, e.g., less than 25 minutes, less than 20 minutes, less than 15 minutes, or less than 10 minutes. In terms of lower limits, the pretreated metal substrate may be heated at the first temperature for at least 10 seconds, e.g., at least 15 seconds, at least 30 seconds, at least 60 seconds, at least 75 seconds, or at least 90 seconds.

In some cases, for example, the pretreated metal substrate is heated at the first temperature for about 1 minute, about 2 minutes, about 3 minutes, about 4 minutes, about 5 minutes, about 6 minutes, about 7 minutes, about 8 minutes, about 9 minutes, or about 10 minutes, or any length of time therebetween.

In some embodiments, the first temperature may be maintained during the period of time by an appropriate heating process. In some cases, for example, heat may be continuously and/or continually applied to the pretreated metal substrate for the period of time.

In some embodiments, the first temperature may not be maintained during the period of time. In some cases, for example, the pretreated metal substrate may be exposed to the first temperature, and no additional heat may be applied during the period of time, such that the temperature at which the pretreated metal substrate is heated during the period of time may diminish slightly, e.g., by less than 25° C., less than 20° C., less than 15° C., less than 10° C., less than 5° C., less than 3° C., less than 2° C., or less than 1° C.

In some embodiments, the thermal modification includes additional heating steps. For example, the pretreated metal substrate may be heated at a second temperature (e.g., before and/or after having been heated at the first temperature). In some cases, heating at the second temperature, according to the described methods, further enhances the pretreatment film, e.g., by drying and/or densifying the pretreatment film. As a result, the corrosion resistant substrate may demonstrate improved adhesion, bond durability, and/or corrosion resistance.

The second temperature is generally a higher temperature relative to conventional methods. The second temperature may or may not be related to the first temperature. In some embodiments, for example, the second temperature is less than the first temperature. In some embodiments, the first temperature and the second temperature are about the same.

In some embodiments, the second temperature is from 75° C. to 250° C., e.g., from 75° C. to 240° C., from 75° C. to 230° C., from 75° C. to 220° C., from 75° C. to 210° C., from 75° C. to 200° C., from 80° C. to 250° C., from 80° C. to 240° C., from 80° C. to 230° C., from 80° C. to 220° C., from 80° C. to 210° C., from 80° C. to 200° C., from 85° C. to 250° C., from 85° C. to 240° C., from 85° C. to 230° C., from 85° C. to 220° C., from 85° C. to 210° C., from 85° C. to 200° C., from 90° C. to 250° C., from 90° C. to 240° C., from 90° C. to 230° C., from 90° C. to 220° C., from 90° C. to 210° C., from 90° C. to 200° C., from 95° C. to 250° C., from 95° C. to 240° C., from 95° C. to 230° C., from 95° C. to 220° C., from 95° C. to 210° C., from 95° C. to 200° C., from 100° C. to 250° C., from 100° C. to 240° C., from 100° C. to 230° C., from 100° C. to 220° C., from 100° C. to 210° C., or from 100° C. to 200° C. In some embodiments, the second temperature is from 150° C. to 250° C., e.g., from 150° C. to 240° C., from 150° C. to 230° C., from 150° C. to 220° C., from 150° C. to 210° C., from 150° C. to 200° C., from 155° C. to 250° C., from 155° C. to 240° C., from 155° C. to 230° C., from 155° C. to 220° C., from 155° C. to 210° C., from 155° C. to 200° C., from 160° C. to 250° C., from 160° C. to 240° C., from 160° C. to 230° C., from 160° C. to 220° C., from 160° C. to 210° C., from 160° C. to 200° C., from 165° C. to 250° C., from 165° C. to 240° C., from 165° C. to 230° C., from 165° C. to 220° C., from 165° C. to 210° C., from 165° C. to 200° C., from 170° C. to 250° C., from 170° C. to 240° C., from 170° C. to 230° C., from 170° C. to 220° C., from 170° C. to 210° C., from 170° C. to 200° C., from 175° C. to 250° C., from 175° C. to 240° C., from 175° C. to 230° C., from 175° C. to 220° C., from 175° C. to 210° C., from 175° C. to 200° C., from 180° C. to 250° C., from 180° C. to 240° C., from 180° C. to 230° C., from 180° C. to 220° C., from 180° C. to 210° C., or from 180° C. to 200° C.

In terms of upper limits, the second temperature may be less than 250° C., e.g., less than 240° C., less than 230° C., less than 220° C., less than 210° C., or less than 200° C. In terms of lower limits, the second temperature may be greater than 75° C., e.g., greater than 80° C., greater than 85° C., greater than 90° C., greater than 95° C., or greater than 100° C.

In some cases, for example, the second temperature may be 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., about 100° C., about 101° C., about 102° C., about 103° C., about 104° C., about 105° C., about 106° C., about 107° C., about 108° C., about 109° C., about 110° C., about 111° C., about 112° C., about 113° C., about 114° C., about 115° C., about 116° C., about 117° C., about 118° C., about 119° C., about 120° C., about 121° C., about 122° C., about 123° C., about 124° C., about 125° C., about 126° C., about 127° C., about 128° C., about 129° C., about 130° C., about 131° C., about 132° C., about 133° C., about 134° C., about 135° C., about 136° C., about 137° C., about 138° C., about 139° C., about 140° C., about 141° C., about 142° C., about 143° C., about 144° C., about 145° C., about 146° C., about 147° C., about 148° C., about 149° C., or about 150° C., or any temperature therebetween.

As with the first temperature, in some cases, the pretreated metal substrate may be heated at the second temperature for a prolonged time. In some embodiments, the pretreated metal substrate is heated at the second temperature for a period of time greater than the time it is exposed to the first temperature. In some embodiments, the preheated metal substrate is heated at the second temperature for a period of time less than the time it is exposed to the first temperature. In some embodiments, the pretreated metal substrate is exposed to the first temperature and the second temperature for about the same amounts of time.

In some embodiments, the pretreated metal substrate is heated at the second temperature for a period of time from 1 hour to 48 hours, e.g., from 1 hour to 42 hours, from 1 hour to 38 hours, from 1 hour to 34 hours, from 1 hour to 30 hours, from 2 hours to 48 hours, from 2 hours to 42 hours, from 2 hours to 38 hours, from 2 hours to 34 hours, from 2 hours to 30 hours, from 4 hours to 48 hours, from 4 hours to 42 hours, from 4 hours to 38 hours, from 4 hours to 34 hours, from 4 hours to 30 hours, from 8 hours to 48 hours, from 8 hours to 42 hours, from 8 hours to 38 hours, from 8 hours to 34 hours, from 8 hours to 30 hours, from 12 hours to 48 hours, from 12 hours to 42 hours, from 12 hours to 38 hours, from 12 hours to 34 hours, from 12 hours to 30 hours, from 18 hours to 48 hours, from 18 hours to 42 hours, from 18 hours to 38 hours, from 18 hours to 34 hours, from 18 hours to 30 hours, from 22 hours to 48 hours, from 22 hours to 42 hours, from 22 hours to 38 hours, from 22 hours to 34 hours, or from 22 hours to 30 hours.

In terms of upper limits, the pretreated metal substrate may be heated at the second temperature for less than 48 hours, e.g., less than 42 hours, less than 38 hours, less than 34 hours, or less than 30 hours. In terms of lower limits, the pretreated metal substrate may be heated at the second temperature for at least 1 hour, e.g., at least 2 hours, at least 4 hours, at least 8 hours, at least 12 hours, at least 18 hours, or at least 22 hours.

In some cases, for example, the pretreated metal substrate is heated at the second temperature for about 18 hours, about 19 hours, about 20 hours, about 21 hours, about 22 hours, about 23 hours, about 24 hours, about 25 hours, about 26 hours, about 27 hours, about 28 hours, about 29 hours, about 30 hours, about 31 hours, or about 32 hours, or any length of time therebetween.

As with the first temperature, in some embodiments, the second temperature may be maintained during the period of time by an appropriate heating process. In some cases, for example, heat may be continuously and/or continually applied to the pretreated metal substrate for a period of time. In some embodiments, the second temperature may not be maintained during the period of time. In some cases, for example, the pretreated metal substrate may be exposed to the second temperature, and no additional heat may be applied during the period of time, such that the temperature at which the pretreated metal substrate is heated during the period of time may diminish slightly, e.g., by less than 25° C., less than 20° C., less than 15° C., less than 10° C., less than 5° C., less than 3° C., less than 2° C., or less than 1° C.

The thermal modification of the described methods may artificially age the pretreated metal substrate. That is, the corrosion resistant substrate produced by the methods described herein may be an artificially aged alloy. Artificial aging may be accomplished, for example, by heating the pretreated metal substrate at the first temperature alone and/or by heating the pretreated metal substrate at both the first temperature and the second temperature.

By artificially aging the pretreated metal substrate, the thermal modification described herein produces a corrosion resistant substrate in a different temper from that of the metal substrate and/or the pretreated metal substrate. In some embodiments, for example, the metal substrate is in an F temper or a T4 temper, and the thermal modification produces a substrate in a T6 temper. Further discussion of the temper of the corrosion resistant substrate is provided below.

Corrosion Resistant Substrate

The methods described herein produce a corrosion resistant substrate. In particular, the methods produce a corrosion resistant substrate having a pretreatment film (e.g., an enhanced pretreatment film, such as a dried pretreatment film or a densified pretreatment film). The pretreatment film imparts desirable characteristics, such as corrosion resistance and/or increased adhesion, on the corrosion resistant substrate. As a result of the described methods, the corrosion resistant substrate demonstrates excellent bond durability, adhesion, and/or corrosion resistance.

In some embodiments, the thermal modification does not alter (e.g., chemically alter) the pretreatment film. In some cases, for example, the chemical composition of the pretreatment film is substantially unchanged by the thermal modification. In some cases, the thermal modification dries the pretreatment film (e.g., removes adsorbed and/or absorbed water). The pretreatment film of the corrosion resistant substrate may comprise an oxide layer. For example, the pretreatment film of the corrosion resistant substrate may comprise an inorganic oxide layer. The oxide layer comprises one or more oxides, such as metallic oxides. In particular, the pretreatment film of the corrosion resistant substrate may comprise any of the oxides discussed above or combinations thereof.

In some cases, exposing an aluminum alloy to high temperatures causes surface enrichment of certain alloying elements. For example, high temperatures typically cause surface enrichment of magnesium and/or silicon, which can contribute to corrosion. Surface enrichment of these and other elements is not an issue for the thermal modification of the present disclosure, because the pretreatment film (e.g., the oxide layer) may act as a barrier.

In some cases, the physical structure of the pretreatment film after thermal modification is unchanged as compared to the physical structure of the pretreatment film before the thermal modification as described herein. In some cases, the thermal modification forms metal-oxide bridges, producing a dense, anhydrous oxide film. As noted above, the pretreatment film on the pretreated metal substrate may be composed of multiple layers. These layers may remain intact after the thermal modification. For example, the corrosion resistant substrate may include a pretreatment film including a barrier layer (e.g., composed of aluminum oxide, such as nonporous aluminum oxide) and a filament layer (e.g., composed of aluminum oxide, such porous aluminum oxide).

As noted above, thermal modification may artificially age the pretreated metal substrate. Thus, the corrosion resistant substrate may be in a temper corresponding to an artificially aged alloy. In some embodiments, the corrosion resistant substrate is in a T5 temper, a T6 temper, a T61 temper, a T7 temper, T8x temper, or a T9 temper. In some cases, in particular, the corrosion resistant substrate may be in a T6 temper.

Use of Corrosion Resistant Substrate

The corrosion resistant 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. Preparing the corrosion resistant substrate as a continuous coil provides a product that is deformable without damaging the pretreatment.

In certain aspects, the corrosion resistant substrates can be coated, e.g., Zn-phosphated and electrocoated (E-coated). The corrosion resistant substrates display an improved adhesion of coatings as compared to continuous coils that do not contain a pretreatment film.

In some further aspects, the corrosion resistant 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 corrosion resistant 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.

In some further aspects, the corrosion resistant substrates display excellent bond durability.

In some examples, the corrosion resistant substrates can be used for chassis, cross-member, and intra-chassis components (encompassing, but not limited to, all 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 aspects, the corrosion resistant 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-pillars, B-pillars, and C-pillars), inner panels, side panels, floor panels, tunnels, structure panels, reinforcement panels, inner hoods, or trunk lid panels. The disclosed corrosion resistant substrates can also be used in aircraft or railway vehicle applications, to prepare, for example, external and internal panels.

In some examples, the corrosion resistant substrates can also be used to prepare housings for electronic devices, including mobile phones and tablet computers. For example, the corrosion resistant 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.

The corrosion resistant substrates can be used in any other desired application.

Illustrations

Illustration 1 is a method of making a corrosion resistant substrate, the method comprising: producing a pretreatment film on a surface of a metal substrate to provide a pretreated metal substrate; and heating the pretreated metal substrate at a first temperature to provide the corrosion resistant substrate, wherein the first temperature is greater than 300° C.; and wherein the metal substrate and/or the pretreated metal substrate is in an F temper, a T4 temper, or a T6 temper.

Illustration 2 is the method of any preceding or subsequent illustration, wherein the metal substrate comprises an aluminum alloy.

Illustration 3 is the method of any preceding or subsequent illustration, wherein the metal substrate comprises a 5xxx series aluminum alloy, a 6xxx series aluminum alloy, or a 7xxx series aluminum alloy.

Illustration 4 is the method of any preceding or subsequent illustration, wherein the corrosion resistant substrate is in a T6 temper.

Illustration 5 is the method of any preceding or subsequent illustration, wherein the pretreatment film comprises an oxide layer.

Illustration 6 is the method of any preceding or subsequent illustration, wherein the oxide layer comprises an aluminum oxide, a silicon oxide, a titanium oxide, a chromium oxide, a manganese oxide, a nickel oxide, a yttrium oxide, a zirconium oxide, a molybdenum oxide, or combinations thereof.

Illustration 7 is the method of any preceding or subsequent illustration, wherein producing the pretreatment film comprises applying an inorganic pretreatment composition to the surface of the metal substrate.

Illustration 8 is the method of any preceding or subsequent illustration, wherein producing the pretreatment film comprises anodizing the surface of the metal substrate.

Illustration 9 is the method of any preceding or subsequent illustration, wherein producing the pretreatment film comprises flame hydrolyzing the surface of the metal substrate.

Illustration 10 is the method of any preceding or subsequent illustration, wherein the first temperature is from 300° C. to 550° C.

Illustration 11 is the method of any preceding or subsequent illustration, wherein the heating comprises heating the pretreated metal substrate at the first temperature for less than 30 minutes.

Illustration 12 is the method of any preceding or subsequent illustration, wherein the heating further comprises heating the pretreated metal substrate at a second temperature.

Illustration 13 is the method of any preceding or subsequent illustration, wherein the second temperature is lower than the first temperature.

Illustration 14 is the method of any preceding or subsequent illustration, wherein the second temperature is from 75° C. to 250° C.

Illustration 15 is the method of any preceding or subsequent illustration, wherein the heating comprises heating the pretreated metal substrate at the second temperature from 1 hour to 48 hours.

Illustration 16 is the method of any preceding or subsequent illustration, wherein the metal substrate is a continuous coil.

Illustration 17 is a corrosion resistant coil comprising: an aluminum alloy continuous coil, wherein a surface of the aluminum alloy continuous coil comprises an inorganic pretreatment film, and wherein the aluminum alloy continuous coil is in an F temper, a T4 temper, or a T6 temper.

Illustration 18 is the method of any preceding or subsequent illustration, wherein the aluminum alloy continuous coil comprises a 5xxx series aluminum alloy, a 6xxx series aluminum alloy, or a 7xxx series aluminum alloy.

Illustration 19 is the corrosion resistant coil of any preceding or subsequent illustration, wherein the inorganic pretreatment film comprises an oxide layer.

Illustration 20 is the corrosion resistant coil of any preceding or subsequent illustration, wherein the oxide layer comprises an aluminum oxide, a silicon oxide, a titanium oxide, a chromium oxide, a manganese oxide, a nickel oxide, a yttrium oxide, a zirconium oxide, a molybdenum oxide, or combinations thereof.

Illustration 21 is a method of making a corrosion resistant substrate, the method comprising producing a pretreatment film on a surface of a metal substrate to provide a pretreated metal substrate; and heating the pretreated metal substrate at a first temperature to provide the corrosion resistant substrate, wherein the metal substrate and/or the pretreated metal substrate is in an F temper, and wherein the corrosion resistant substrate is in a T5 temper, a T6 temper, a T61 temper, a T7 temper, T8x temper, or a T9 temper.

EXAMPLES

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

As noted above, the thermal modification method described herein produces corrosion resistant substrates that demonstrate excellent bond durability. This example serves to illustrate the improvement of the bond durability of corrosion resistant substrates produced according to the methods described herein relative to metallic substrates pretreated according to conventional methods and not thermally modified.

Several samples of a corrosion resistant substrate were prepared according to the disclosed methods using an AA7075 aluminum alloy to test the properties of the corrosion resistant substrate. Each of the samples tested is shown in Table 1. Samples were prepared with varying pretreatment methods and comprising varying components, as indicated in Table 1. Furthermore, samples were prepared from varying tempers, as indicated in Table 1. Each sample was subjected to thermal modification as follows: each sample was heated at 485° C. for 5 minutes, and subsequently heated at 125° C. for 24 hours. Following this thermal modification, each sample was in a T6 temper.

As shown in Table 1, several comparative samples (Comp. 1-7) were also prepared and tests. The comparative samples were prepared by producing a pretreatment film. These samples did not undergo thermal modification.

TABLE 1 Intl. Pretreatment Final Sample ID Temper Film Thermal Modification Temper Sample 1 F Anodized, 485° C. for 5 minutes; T6 Al Oxide 125° C. for 24 hours Sample 2 F Anodized, 485° C. for 5 minutes; T6 Al Oxide 125° C. for 24 hours Sample 3 F Anodized, 485° C. for 5 minutes; T6 Al Oxide 125° C. for 24 hours Sample 4 T6 Anodized, 485° C. for 5 minutes; T6 Al Oxide 125° C. for 24 hours Sample 5 T6 Anodized, 485° C. for 5 minutes; T6 Al Oxide 125° C. for 24 hours Sample 6 T6 Anodized, 485° C. for 5 minutes; T6 Al Oxide 125° C. for 24 hours Sample 7 F Flame 485° C. for 5 minutes; T6 hydrolyzed, 125° C. for 24 hours Si Oxide Sample 8 F Flame 485° C. for 5 minutes; T6 hydrolyzed, 125° C. for 24 hours Si Oxide Sample 9 F Flame 485° C. for 5 minutes; T6 hydrolyzed, 125° C. for 24 hours Si Oxide Sample 10 F Flame 485° C. for 5 mins; T6 hydrolyzed, 125° C. for 24 hours Si Oxide Sample 11 F Inorg. 485° C. for 5 mins; T6 composition, 125° C. for 24 hours Ti Oxide/Zr Oxide Sample 12 F Combination 485° C. for 5 mins; T6 (org. & inorg.) 125° C. for 24 hours pretreatment Sample 13 F Combination 485° C. for 5 mins; T6 (org. & inorg.) 125° C. for 24 hours pretreatment Comp. 1 T6 Anodized, N/A T6 Al Oxide Comp. 2 T6 Anodized, N/A T6 Al Oxide Comp. 3 T6 Anodized, N/A T6 Al Oxide Comp. 4 T6 Anodized, N/A T6 Al Oxide Comp. 5 T6 Anodized, N/A T6 Al Oxide Comp. 6 T6 Anodized, N/A T6 Al Oxide Comp. 7 T6 Flame N/A T6 hydrolyzed, Si Oxide

The above samples and comparatives were subjected to bond durability testing. In this testing, a set of six 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 four joints, the test is discontinued for the particular set of joints and is indicated as a bond failure. For this disclosure, the completion of 45 cycles without a bond failure indicates that the set of joints passed the bond durability test. Upon the completion of 60 cycles, the test is discontinued.

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. Unless otherwise noted, the number in the cells indicates the number of successful cycles before a break. An asterisk (“*”) next to a number indicates that the joint was unbroken but that the test was discontinued. The results are summarized in Table 2 below:

TABLE 2 Bond Durability Test Coupon Arrangement 1 6 Trial Sample Top 2 3 4 5 Bottom  1 Sample 1 60* 60* 60* 60*  60*  60*  2 Sample 2 60* 60* 60* 60*  60*  60*  3 Sample 3 60* 60* 60* 60*  60*  60*  4 Sample 4 53* 46  53* 45  53 50  5 Sample 5 40* 40* 39  40  34 29  6 Sample 6 47* 24  47* 27  47 26  7 Sample 7 60* 60  59  60* 59  60*  8 Sample 8 52* 52* 49  48  52 50  9 Sample 9 51* 44  50  49  51  51* 10 Sample 10 57* 52  57  50   57* 56 11 Sample 11 60* 60* 60* 60*  60*  60* 12 Sample 12  7*  7* 6 7  7  5 13 Sample 13 10* 10* 10  8  8  9 14 Comp. 1  7*  7* 5 5  7  6 15 Comp. 2 21* 21* 16  13  15 21 16 Comp. 3 10* 10* 10  7  7  5 17 Comp. 4 10* 8 9 10* 10  6 18 Comp. 5 11* 11* 11  9  5 10 19 Comp. 6 25* 25* 24  25  23 15 20 Comp. 7 2  4*  4* 4  4  4

The exemplary corrosion resistant substrates which were subjected to thermal modification according to the present disclosure demonstrated excellent bond durability, with all but three samples (Sample 5, Sample 12, and Sample 13) passing the test. Notably, two of the three samples that did not pass the durability test included organic pretreatment films. The comparative substrates demonstrated comparatively poorer bond durability, with each comparative substrate failing the durability test.

Example 2: Bond Durability Testing

This example further illustrates the improvement of the bond durability of corrosion resistant substrates produced according to the methods described herein relative to metallic substrates pretreated according to conventional methods and not thermally modified.

Several samples of a corrosion resistant substrate were prepared according to the disclosed methods using an AA7075 aluminum alloy to test the properties of the corrosion resistant substrate. Each of the samples tested is shown in Table 3. Samples were prepared by etching with an acid and applying a varying titanium/zirconium pretreatment (Gardobond 4591 from Chemetall GmbH (Frankfurt, Germany)), as detailed in Table 3. Each sample was prepared at an initial F temper. Each sample was thermally modified to adjust the temper, as indicated in Table 3.

TABLE 3 Intl. Pretreatment Thermal Final Sample ID Temper Acid Etch Film Modification Temper Sample 14 F 0.2 g/m2, Ti: 22 mg/m2, 125° C. for T6 65° C., Zr: 20 mg/m2, 24 hours 5 seconds 5 seconds 25° C. Sample 15 F 0.2 g/m2, Ti: 22 mg/m2, 125° C. for T6 65° C., Zr: 20 mg/m2, 24 hours 5 seconds 5 seconds 25° C. Sample 16 F 0.2 g/m2, Ti: 17 mg/m2, 125° C. for T6 50° C., Zr: 11 mg/m2, 24 hours 1 second 10 seconds 25° C. Sample 17 F 0.2 g/m2, Ti: 17 mg/m2, 125° C. for T6 50° C., Zr: 11 mg/m2, 24 hours 1 second 10 seconds 25° C. Sample 18 F 0.8 g/m2, Ti: 13 mg/m2, 125° C. for T6 50° C., Zr: 8 mg/m2, 24 hours 5 seconds 10 second 25° C. Sample 19 F 0.8 g/m2, Ti: 13 mg/m2, 125° C. for T6 50° C., Zr: 8 mg/m2, 24 hours 5 seconds 10 seconds 25° C. Sample 20 F 0.2 g/m2, Ti: 42 mg/m2, 125° C. for T6 50° C., Zr: 20 mg/m2, 24 hours 1 second 10 seconds 45° C. Sample 21 F 0.2g/m2, Ti: 42 mg/m2, 125° C. for T6 50° C., Zr: 20 mg/m2, 24 hours 1 second 10 seconds 45° C. Sample 22 F 0.2 g/m2, Ti: 16 mg/m2, 125° C. for T6 50° C., Zr: 12 mg/m2, 24 hours 1 second 10 seconds 25° C. Sample 23 F 0.2 g/m2, Ti: 16 mg/m2, 125° C. for T6 50° C., Zr: 12 mg/m2, 24 hours 1 second 10 seconds 25° C.

The above samples were subjected to bond durability testing. In this testing, a set of six 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 four joints, the test is discontinued for the particular set of joints and is indicated as a bond failure. For this disclosure, the completion of 45 cycles without a bond failure indicates that the set of joints passed the bond durability test. Upon the completion of 60 cycles, the test is discontinued.

The bond durability test results are shown below in Table 4. In Table 4, 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. Unless otherwise noted, the number in the cells indicates the number of successful cycles before a break. An asterisk (“*”) next to a number indicates that the joint was unbroken but that the test was discontinued. The results are summarized in Table 4 below:

TABLE 4 Bond Durability Test Coupon Arrangement 1 6 Sample Top 2 3 4 5 Bottom Sample 14 59* 59* 59  59 56 47 Sample 15 67* 67* 66  67 63 59 Sample 16 64* 59  62  64  64* 63 Sample 17 49* 49* 42* 40 41 49 Sample 18 61* 60  59  61 58  61* Sample 19 63* 63  63* 59 55 56 Sample 20 63  67* 59  67  67* 62 Sample 21 63  63* 49  54  63* 57 Sample 22 71* 59  71* 57 58 71 Sample 23 69* 65  69* 66 64 69

The exemplary corrosion resistant substrates which were subjected to thermal modification according to the present disclosure demonstrated excellent bond durability, with all but one sample (Sample 17) passing the test.

Example 3: GDOES Depth Profiling

Several samples of a corrosion resistant substrate were prepared according to the disclosed methods using an AA7075 aluminum alloy to test the properties of the corrosion resistant substrate. Each of the samples tested is shown in Table 5. Samples were prepared by etching with an acid and applying a varying titanium/zirconium pretreatment (Gardobond 4591 from Chemetall GmbH (Frankfurt, Germany)), as detailed in Table 5. Each sample was prepared at an initial F temper. Each sample was thermally modified to adjust the temper, as indicated in Table 5.

TABLE 3 Intl. Pretreatment Thermal Final Sample ID Temper Acid Etch Film Modification Temper Sample 25 F 0.2 g/m2, Ti: 22 mg/m2, 125° C. for T6 65° C., Zr: 20 mg/m2, 24 hours 5 seconds 10 seconds 65° C. T6 Sample 26 F 0.2 g/m2, Ti: 17 mg/m2, 125° C. for 50° C., Zr: 11 mg/m2, 24 hours 1 second 10 seconds 25° C.

To analyze the surface and depth profile, each sample was subjected to glow discharge optical emission spectrometry (GDOES). GDOES gives the quantitative depth distribution of elements in the thin surface film of each sample. The results of the GDOES depth profiling are illustrated FIG. 1, which shows the enrichment of copper and silicon on the surface of the samples. With regard to copper, Samples 25 and 26 exhibited similar profiles with the presence of copper enrichment after 12 seconds of sputtering. With regard to silicon, Sample 25 had higher yet thinner enrichment of silicon than Sample 26, which may be due to the difference in the acid etching between the two samples.

Claims

1. A method of making a corrosion resistant substrate, the method comprising:

producing a pretreatment film on a surface of a metal substrate to provide a pretreated metal substrate; and
heating the pretreated metal substrate at a first temperature to provide the corrosion resistant substrate,
wherein the first temperature is greater than 300° C., and
wherein the metal substrate and/or the pretreated metal substrate is in an F temper, a T4 temper, or a T6 temper.

2. The method of claim 1, wherein the metal substrate comprises an aluminum alloy.

3. The method of claim 2, wherein the metal substrate comprises a 5xxx series aluminum alloy, a 6xxx series aluminum alloy, or a 7xxx series aluminum alloy.

4. (canceled)

5. The method of claim 1, wherein the pretreatment film comprises an oxide layer.

6. The method of claim 5, wherein the oxide layer comprises an aluminum oxide, a silicon oxide, a titanium oxide, a chromium oxide, a manganese oxide, a nickel oxide, a yttrium oxide, a zirconium oxide, a molybdenum oxide, or combinations thereof.

7. The method of claim 1, wherein producing the pretreatment film comprises applying an inorganic pretreatment composition to the surface of the metal substrate.

8. The method of claim 1, wherein producing the pretreatment film comprises anodizing the surface of the metal substrate.

9. The method of claim 1, wherein producing the pretreatment film comprises flame hydrolyzing the surface of the metal substrate.

10. The method of claim 1, wherein the first temperature is from 300° C. to 550° C.

11. The method of claim 1, wherein the heating comprises heating the pretreated metal substrate at the first temperature for less than 30 minutes.

12. The method of claim 1, wherein the heating further comprises heating the pretreated metal substrate at a second temperature.

13. The method of claim 12, wherein the second temperature is lower than the first temperature.

14. The method of claim 12, wherein the second temperature is from 75° C. to 250° C.

15. The method of claim 12, wherein the heating comprises heating the pretreated metal substrate at the second temperature from 1 hour to 48 hours.

16. The method of claim 1, wherein the metal substrate is a continuous coil.

17. A corrosion resistant coil comprising:

an aluminum alloy continuous coil, wherein a surface of the aluminum alloy continuous coil comprises an inorganic pretreatment film, and
wherein the aluminum alloy continuous coil is in an F temper, a T4 temper, or a T6 temper.

18. The method of claim 17, wherein the aluminum alloy continuous coil comprises a 5xxx series aluminum alloy, a 6xxx series aluminum alloy, or a 7xxx series aluminum alloy.

19. The corrosion resistant coil of claim 17, wherein the inorganic pretreatment film comprises an oxide layer.

20. The corrosion resistant coil of claim 19, wherein the oxide layer comprises an aluminum oxide, a silicon oxide, a titanium oxide, a chromium oxide, a manganese oxide, a nickel oxide, a yttrium oxide, a zirconium oxide, a molybdenum oxide, or combinations thereof.

21. A method of making a corrosion resistant substrate, the method comprising:

producing a pretreatment film on a surface of a metal substrate to provide a pretreated metal substrate; and
heating the pretreated metal substrate at a first temperature to provide the corrosion resistant substrate,
wherein the metal substrate and/or the pretreated metal substrate is in an F temper, and
wherein the corrosion resistant substrate is in a T5 temper, a T6 temper, a T61 temper, a T7 temper, T8x temper, or a T9 temper.
Patent History
Publication number: 20230243060
Type: Application
Filed: Apr 23, 2021
Publication Date: Aug 3, 2023
Applicant: Novelis Inc. (Suite 2000, GA)
Inventors: Theresa Elizabeth MacFarlane (Woodstock, GA), Max Scruggs (Kennesaw, GA), Lasitha Cumaranatunge (Atlanta, GA), Kevin Mark Johnson (Woodstock, GA), Brian Paradis (Marietta, GA), Tudor Piroteala (Woodstock, GA), Peter Lloyd Redmond (Acworth, GA), Duane Bendzinski (Woodstock, GA), Thomas J. Beck (Marietta, GA), Thomas John Beckman (Adairsville, GA)
Application Number: 17/996,563
Classifications
International Classification: C25D 11/18 (20060101); C23C 22/12 (20060101); C22F 1/04 (20060101); C23C 22/82 (20060101);