KR20170092209A

KR20170092209A - Anodizing Aluminum and Alloys Thereof

Info

Publication number: KR20170092209A
Application number: KR1020160013244A
Authority: KR
Inventors: 김성용
Original assignee: 주식회사 에이제이테크
Priority date: 2016-02-03
Filing date: 2016-02-03
Publication date: 2017-08-11

Abstract

A manufacturing method according to the present invention is a method for manufacturing a colored oxide layer and, more specifically, to a method for manufacturing an oxide layer colored on an aluminum substrate by anodizing the aluminum substrate of an electrolyte including water, sulfuric acid, and oxalic acid. The anodizing step can include a step of passing at least two sequence current densities through the electrolyte. In addition, according to the present invention, disclosed are a method for manufacturing an article comprising a colored oxide layer on an aluminum substrate produced by the above method, and the use thereof.

Description

[0002] Anodizing Aluminum and Alloys Thereof [0003]

The present invention relates to a method for producing a colored oxide layer on an aluminum substrate. In particular, the present invention relates to a process for the preparation of a colored oxide layer by anodizing an aluminum substrate in an electrolyte comprising water, oxalic acid and sulfuric acid.

Aluminum and aluminum alloys are known to have suitable properties such as light weight, strength, durability and structural flexibility. In 1889, Alcoa, Inc., an electrolysis process for the production of aluminum from aluminum oxide, has obtained a patent (U.S. Pat. No. 400,664) on a process that significantly reduces the manufacturing cost of aluminum through this process. Since then, aluminum and aluminum alloys have been widely used in aerospace, transportation, construction, semiconductor, and electronics industries with suitable characteristics and low cost. As a result, the widespread use of aluminum has exceeded the usage of all other metals except iron in terms of quantity and price.

Aluminum metal and alloys are used in the manufacture of watches, computers (eg heat sinks for CPUs), computer related products (packaging for hard drives and flash drives), televisions, radios, refrigerators, air conditioners, Parts or components of various goods such as automobiles, marine vessels, bicycles, etc.), packaging materials (cans, foils, etc.), structures (windows, doors, board walls, building wires), cooking utensils, transmission lines, MKM steels and Alnico magnets, .

In addition to the suitable properties mentioned above, aluminum metal and alloys can be anodized to improve corrosion resistance, abrasion resistance, electrical insulation, adhesion and / or aesthetic properties. Generally, anodizing is an electrochemical process that thickens and strengthens the naturally-occurring protective oxide layer of aluminum or an aluminum alloy. The oxide layer or anode coating layer produced according to the process will probably be a material of superior strength known to mankind next to diamond.

The oxide layer generally has a void structure that allows for a second implant (organic and inorganic staining, lubricating acid, etc.) for deformation of the surface.

The aluminum anodizing process may include a batch, a continuous coil, a continuous component, and an anisotropic bath. This anodizing process can compete with other technologies such as painting, lacquering and physical vapor deposition (PVD) to form decorative or protective coatings that can be chosen in various colors, as well as the technical advantages And

An aesthetics of anodizing can be provided. Painting and lacquering, for example, are generally poorly sustainable and do not comply with Restriction of Hazardous Substances (RoHS), which is regulated by the European Union and regulates heavy metals and toxic substances. On the other hand, the PVD process does not provide the desired color selectivity in some cases

However, it does not satisfy the process stability required in mass production.

Although various anodizing processes have been developed, aluminum anodizing includes three major examples: chrome anodizing, sulfuric anodizing, and hard coat anodizing. Such an anodizing process is disclosed in S. Kawai, "Anodizing and Coloring of Aluminum Alloys," ASM International (2002)

.

Chrome anodizing is commonly referred to as type 1 anodizing. The reaction can be carried out at about 40 캜 electrolyte solution containing chromic acid at a current density of about 0.15 A / dm 2 to 0.45 A / dm 2. The process generally takes about 40 to 60 minutes. Through chromium anodizing, a thin oxide layer, typically 1 to 2.5 microns in thickness, can be produced. Because chromic acid is less corrosive than sulfuric acid, chrome anodizing can be used for complex parts that are difficult to clean. Chromium anodizing can reduce the fatigue strength of aluminum compared to other methods described below.

Sulfate anodizing is called type 2 anodizing. The reaction can be carried out at a current density of about 1.0 A / dm 2 to 1.5 A / dm 2 using an electrolyte solution at about 25 ° C containing sulfuric acid. This process generally takes about 30 to 60 minutes depending on the alloy used. Anodizing sulfate can generally produce an oxide layer having a thickness of about 10 to 14 microns. The symbol type 2 can be used to refer to sulfuric acid anodizing, while the symbol of type 2, class 1, can be used to specify that it is a natural color or not, and class 2 can be used to refer to a dye have.

Hard coat anodizing is commonly referred to as type 3 anodizing. Type III oxide layers are typically fabricated at very low temperatures and high current densities. For example, type 3 anodizing can be performed in an electrolyte solution at about 0-5 DEG C containing sulfuric acid, and the current density is about 3.5 A / dm2 to 4.0 A / dm2. The process generally takes 20 to 120 minutes. Hard coat anodizing generally produces an oxide layer having a thickness of about 30 to 60 microns.

The anodizing process can provide advantages over other technologies and can provide a decorative oxide layer of one or more colors without dyeing or dyeing, but the anodizing process, such as Type 2 and Type 3 processes, . For example, the Type 3 anodizing process generally has a high hardness, an opaque oxidation

As the water layer is produced, the dyeing and polishing process can be difficult. In addition, the Type 2 anodizing process can not produce a high degree of hardness and / or gloss that is acceptable for certain decorative coatings. Moreover, since the type 2 anode oxide layer can be dissolved in a corrosion anodizing bath, the thickness of the type 2 oxide layer can be limited. Thicker products may not have corrosion, but nevertheless the surface can be weakened by corrosion, and the oxide layer may have a flow mark, a teardrop, an etched trench, etc. Same surface defect

In order to overcome the disadvantages of the above-mentioned painting, lacquering, PVD and conventional anodizing techniques, anodized and / or mirror-finished anodized surfaces, when applied in decorative and / or protective applications, It is necessary to develop an improved technique for surface treatment of an aluminum substrate so as to provide an anodized surface having excellent hardness and excellent durability.

Accordingly, the present invention is directed to a method of making a colored oxide layer on an aluminum substrate comprising anodizing the aluminum substrate at two different current densities. Specific examples of the raw material composition described below are considered to meet the above-mentioned necessity.

A first invention according to the present invention is a process for producing a colored oxide layer on an aluminum substrate comprising the steps of: (a) placing an aluminum substrate on an anode in an electrolyte comprising water, oxalic acid and sulfuric acid; ; And (b) anodizing the aluminum substrate for 1 minute to 1 hour with a first current of less than 0.5 A / dm 2 density,

And anodizing with a second current of 1.5 A / dm 2 to 2.5 A / dm 2 to produce an oxide layer.

In some specific examples, the aluminum substrate has a density of 1.0 A / dm 2 to 1.5 A / dm

2 can be further anodized. In another specific example, the first current, the second current, and the third current may each be independently generated by a constant direct current or a pulsed direct current.

In some specific examples, the method may further comprise stirring the electrolyte through a stirring device. In another specific example, the stirring device may comprise a stirring tube.

In one specific example, a step of forming a dye layer on the oxide layer may be additionally included.

In another specific example, the electrolyte may further comprise aluminum ions, metal sulfates, organic acids, or combinations thereof. In another specific example, the electrolyte may additionally comprise from 2 g to 11 g of aluminum ion per liter of electrolyte. In one specific example, the electrolyte comprises from 5 g to 40 g oxalic acid per liter of electrolyte and from 100 g to 360 g per liter of electrolyte Sulfuric acid. In another specific example, the electrolyte may comprise from about 12 g to about 20 g of oxalic acid per liter of electrolyte and from about 140 g to about 220 g of sulfuric acid per liter of electrolyte. In another specific example, the electrolyte may comprise from 14 g to 18 g of oxalic acid per liter of electrolyte and from 160 g to 200 g of sulfuric acid per liter of electrolyte.

In one specific example, the anodizing step can be performed at a temperature of from 5 ° C to 25 ° C. In another specific example, the anodizing step may be carried out at a temperature of from < RTI ID = 0.0 > 10 C < / RTI >

In one specific example, the aluminum substrate is made of aluminum and, optionally, silicon, boron, germanium, arsenic, antimony, tellurium, copper, magnesium, manganese, zinc, lithium, Wherein the element is selected from the group consisting of vanadium, titanium, bismuth, gallium, tin, lead, zirconium, nickel, cobalt and combinations thereof.

.

The present invention also relates to an article comprising an aluminum substrate having a colored oxide layer on an aluminum substrate, said colored oxide layer comprising (a) an electrolyte comprising water, oxalic acid and sulfuric acid, A stage in which the substrate is arranged on the anode

system; And (b) anodizing the aluminum substrate with a first current of less than 0.8 A / dm 2 for 1 minute to 1 hour, and then anodizing with a second current of 1.5 A / dm 2 to 2.5 A / The oxide layer may have a microhardness of 280 to 1000 Hv. In one embodiment, the colored oxide layer may have a microhardness of 280 to 1000 Hv . In another specific example, the colored oxide layer may be from 15 microns to 50 microns in thickness. In another specific example, the article may further comprise a layer of dye on the oxide layer. In one specific example, the surface of the colored oxide layer may have an Ra value of 0.01 to 0.1 microns.

Included in the content of the solution

1 is a photograph showing an anode oxide layer on an aluminum substrate comprising an anode cell having a gap per cell;
Fig. 2 is a photograph showing the surface color and finish of Example 1, Comparative Example D and Comparative Example E. Fig.

&Quot; Substantially pure "metal as used herein refers to a metal or alloy in which substantially no one or more other elements or compounds are present, for example, greater than 80 wt%, 90 wt% , Greater than 99 wt.%, Greater than 99 wt.%, Greater than 97 wt.%, Greater than 98 wt.%, Greater than 99 wt.%, Greater than 99.5 wt.%, Greater than 99.6 wt. A metal or alloy comprising more than one metal or alloy; Less than 20 wt%, less than 10 wt%, less than 5 wt%, less than 3 wt%, less than 1 wt%, less than 0.5 wt%, less than 0.1 wt%, or less than 0.01 wt% based on the total weight of the metal or alloy &Lt; / RTI > of one or more of the other elements or compounds.

The metal or alloy in which the element or compound used is " substantially free "is less than 20 wt%, less than 10 wt%, less than 5 wt%, less than 4 wt%, less than 3 wt% Refers to a metal or metal alloy comprising less than 2 wt%, less than 1 wt%, less than 0.5 wt%, less than 0.1 wt%, or less than 0.01 wt% of an element or compound. Means a material made of the above metal. In general, alloys are designed and manufactured to have certain, desired properties, including strength, formability and corrosion resistance.

As used herein, Ra means an arithmetic mean deviation of an absolute value of a roughness profile measured from an average line or a center line,

known as centerline average roughness (CLA). The centerline divides all the areas above it equally with all areas below it.

Rq used herein means the root mean square or geometric mean deviation of the roughness profile from the mean line measured at the sample length.

As used herein, "buffing" or "polishing treatment" means polishing a product such as a metal or an alloy so that it can be brightly and smoothly mirror-polished.

In the following detailed description, all the numbers disclosed represent approximate values regardless of whether the term "about" or "approximately" They can vary from 1 percent, 2 percent, 5 percent, or sometimes 10 to 20 percent. Every time the lower limit RL and the upper limit RU are disclosed, a range of numbers is deemed to be specifically disclosed. In particular, the following numbers within the above ranges are deemed to be specifically disclosed:

R = RL + k * (RU- RL), where k is a variable ranging from 1 percent to 100 percent in 1 percent difference, for example k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, … , 50 percent, 51 percent, 52 percent, ... , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Furthermore, the numerical ranges defined by the two numbers R as defined above are also contemplated to be specifically disclosed. The present invention provides a method of making a colored oxide layer on an aluminum substrate comprising the steps of: (a) disposing an aluminum substrate as an anode in an electrolyte including oxalic acid and sulfuric acid; And (b) anodizing the aluminum substrate at a first current density of less than 0.8 A / dm 2 for one to four hours and then anodizing the second substrate at a second current density of 1.5 A / dm 2 to 2.5 A / To produce a colored oxide layer comprising the oxide layer.

The present invention also relates to an article comprising an aluminum substrate having a colored oxide layer on an aluminum substrate, said coloring oxide layer comprising (a) an electrolyte comprising water, oxalic acid and sulfuric acid, To an anode; And (b) a first current of less than 0.8 A / dm < 2 >

Anodizing the substrate and then anodizing to a second current having a density of 1.5 A / dm 2 to 2.5 A / dm 2 to produce an oxide layer. In some specific examples, the oxide layer may be a colored oxide layer. In another specific example, the oxide layer may be opaque, colored.

In another specific example, the oxide layer may be transparent and colored.

The article may be a pen, a lighter, a watch, a computer, a computer-related product (hard drive, flash drive, DVD drive, etc.), a printer, a copier, a fax machine, a television, a radio, a refrigerator, It can be made or used as a component or component in a variety of products, such as architectural finishes and decorations, machines, or in other areas where the decoration and special physical properties of aluminum coated with good strength are required.

Aluminum substrates suitable for the above methods and articles may be aluminum metal which is substantially free of other elements or compounds or may be a known aluminum alloy. Aluminum metal may be suitable in many applications, but in some cases it may be preferable to use aluminum alloys because of improved chemical, physical and mechanical properties relative to aluminum metal. In general, aluminum alloys can be made by mixing aluminum with other elements through a thermo-mechanical process. A brief historical overview of alloys and their manufacturing techniques is provided in Joseph R. Davis, "Aluminum and Aluminum Alloys," ASM International, (1993); And R.E. Sanders, " Technology Innovation in Aluminum Products, "The Journal of The Minerals, 53 (2), pp. 21-25 (2001), all of which are incorporated herein by reference.

In general, aluminum alloys exhibit improved mechanical properties such as high strength: weight ratio, especially when alloys are tempered. A large amount of metal is widely referred to as "aluminum", but in fact many of them are replacing aluminum alloys. For example, most aluminum foils consist of an alloy comprising 92 wt% to 99 wt% aluminum.

In one specific example, the aluminum substrate comprises substantially other elements such as substantially copper, zinc, magnesium, manganese, silicon, lithium, iron, chromium, vanadium, titanium, bismuth, gallium, lead, zirconium, Aluminum metal. In one specific example, the aluminum substrate has a total weight of

By weight of aluminum, greater than 96% aluminum, greater than 97% aluminum, greater than 98% aluminum, greater than 99% aluminum, greater than 99.5% aluminum, greater than 99.9% , Or greater than 99.99 wt% aluminum. In one specific example, the aluminum substrate may comprise 99 wt% or more aluminum based on the total weight of the aluminum substrate. The aluminum may include, but is not limited to, 1000 series aluminum metal, for example, 1060 and 1100 listed in Table 1.

In another specific example, the aluminum substrate may be an aluminum alloy. Aluminum can easily form alloys with semimetals, metals and combinations thereof. The semi-metal may be, but not limited to, silicon, boron, germanium, arsenic, antimony, tellurium, and the like. The metal may be copper, zinc, magnesium, manganese, lithium, iron, chromium,

Vanadium, titanium, bismuth, gallium, lead, zirconium, and the like. In general, copper can increase strength, hardness and heat-treatability. Magnesium can increase tensile strength, resistance to seawater corrosion, weldability and hardness. Manganese can increase strength and resistance to corrosion. Silicon

Lowering the melting point and improving the castability; Zinc can increase the strength and hardness of the alloy.

There are a variety of aluminum alloys categorized by many different groups. For example, commonly used aluminum alloy compositions are registered in the Aluminum Association. Meanwhile, many other organizations, including the Society of Automotive Engineers Standards Association and ASTM, are providing more specific standards for the production of aluminum alloys. Alternatively, aluminum alloys can be classified into names including number systems (e.g., ANSI) or their main alloy composition (e.g., DIN and ISO).

The aluminum alloy used herein may comprise a non-aluminum component comprising aluminum and at least one or more semimetals and other metals. In some specific examples, the semimetals and other metals are selected from the group consisting of silicon, boron, germanium, arsenic, antimony, tellurium, copper, magnesium, manganese, zinc, lithium, iron, chromium, vanadium, titanium, bismuth, gallium, , Zirconium, nickel, cobalt, and combinations thereof. In one specific example, the aluminum alloy comprises more than 85 wt% aluminum, more than 87 wt% aluminum, more than 90 wt% aluminum, more than 92 wt% aluminum, more than 93 wt% aluminum, 94 wt% aluminum By weight, and more than 95% by weight of aluminum. In one specific example, the aluminum alloy comprises greater than 1 wt%, greater than 2 wt%, greater than 3 wt%, greater than 4 wt%, greater than 5 wt%, greater than 6 wt%, less than 7 wt% Of the non-aluminum element.

In another specific example, the aluminum alloy may be an alloy comprising aluminum and copper. In one specific example, the aluminum alloy comprises greater than 1 weight percent copper, greater than 2 weight percent copper, greater than 3 weight percent copper, greater than 4 weight percent copper, greater than 5 weight percent copper, greater than 6 weight percent copper, By weight, and more than 7% by weight of copper.

In another specific example, the aluminum alloy may be an alloy including aluminum and magnesium. In one specific example, the aluminum alloy comprises greater than 1 weight percent magnesium, greater than 2 weight percent magnesium, greater than 3 weight percent magnesium, greater than 4 weight percent magnesium, greater than 5 weight percent magnesium, greater than 6 weight percent magnesium, By weight, and more than 7% by weight of magnesium. In some specific examples, the aluminum alloy may be substantially free of magnesium.

In another specific example, the aluminum alloy may be an alloy including aluminum and manganese. In one specific example, the aluminum alloy comprises greater than 1 wt% manganese, greater than 2 wt% manganese, greater than 3 wt% manganese, greater than 4 wt% manganese, greater than 5 wt% manganese, greater than 6 wt% By weight, and more than 7% by weight of manganese. In another specific example, the aluminum alloy may be substantially free of manganese.

In another specific example, the aluminum alloy may be an alloy including aluminum and silicon. In one specific example, the aluminum alloy comprises greater than 1 weight percent silicon, greater than 2 weight percent silicon, greater than 3 weight percent silicon, greater than 4 weight percent silicon, greater than 5 weight percent silicon, greater than 6 weight percent silicon, By weight, more than 7% by weight of silicone

. In another specific example, the aluminum alloy may be substantially free of silicon.

In another specific example, the aluminum alloy may be an alloy including aluminum and zinc. In one specific example, the aluminum alloy comprises greater than 1 weight percent zinc, greater than 2 weight percent zinc, greater than 3 weight percent zinc, greater than 4 weight percent zinc, greater than 5 weight percent zinc, greater than 6 weight percent zinc, By weight, and more than 7% by weight of zinc.

In another specific example, the aluminum alloy may be substantially free of zinc.

In another specific example, the aluminum alloy may be an alloy comprising aluminum and tin. In one specific example, the aluminum alloy comprises greater than 1 weight percent tin, greater than 2 weight percent tin, greater than 3 weight percent tin, greater than 4 weight percent tin, greater than 5 weight percent tin, greater than 6 weight percent tin, By weight, and more than 7% by weight of tin. Other

In a specific example, the aluminum alloy may be substantially free of tin.

In one specific example, an aluminum alloy suitable for forming the oxide layer described herein may be a processed aluminum alloy. Typically, the processed aluminum contains four numbers that identify alloying elements, followed by a dash (-), letters delimited by the heat treatment type, and numbers 1-4 For example, 6061-T6, a commonly used free-machining aluminum alloy, can be distinguished. The physical properties of the aluminum alloy may be affected by the heat treatment and the degree of annealing. Suitable aluminum alloys and their composition are set forth in Table 1 below, but are not limited to, any worked aluminum alloy known to those skilled in the art May be suitable for forming the oxide layer described herein.

In one specific example, the aluminum alloy may be one of 2000 series, 3000 series, 4000 series, 5000 series, 6000 series, or 7000 series alloys. In general, the major non-aluminum alloy components used in 1000 series, 2000 series, 3000 series, 4000 series, 5000 series, 6000 series, or 7000 series aluminum alloys are copper, manganese, silicon, magnesium, magnesium / Zinc. Suitable aluminum alloys for processing may include, but are not limited to, the alloys listed in Table 1, as well as 2011, 2017, 4032, 5005, 6061, and the like.

In another specific example, each of the 1000 series, 2000 series, 3000 series, 4000 series, 5000 series, 6000 series, or 7000 series aluminum alloys can be heat treated and thus has a temper code designation F, O, < / RTI > T or H.

The symbol "F" is manufactured without any special treatment such as casting, hot working or cold working in heat treatment after strain shaping or strain hardening fabricated state.

The symbol "O" means an annealed alloy. It has the lowest strength and the highest ductility temper.

The symbol "T" refers to an alloy reinforced by heat treatment, with or without subsequent strain hardening treatment.

The above T code is as follows.

T1 A state of stabilization by shaping process at high temperature, followed by cooling and natural aging.

T2 Molded at high temperature, cooled, then cold worked, and then subjected to natural aging to be substantially stable.

Solution for T3 Solution After heat treatment, it is cold-worked, and is subjected to a natural aging treatment to be substantially stabilized.

After T4 solution heat treatment, it is subjected to a natural aging treatment to be substantially stabilized.

T5 Molded at high temperature, then cooled and artificially aged.

After T6 solution heat treatment, artificially aged.

After heat-treatment for T7, it is stabilized by over-heating.

T8 Solution After heat treatment, cold working, artificial aging.

T9 Forming After heat-treating, artificially aging, and then cold-working.

T10 Molded at high temperature, artificially aged after cold working.

The symbol "H" means an alloy reinforced by strain hardening without subsequent heat treatment or heat treatment. H strain hardening code is as follows.

H1 Only strain hardened.

H2 strain hardened and partially annealed.

H3 strain hardened and stabilized.

H4 strain hardened, lacquered or painted. This considers that the temperature effect in the coating process can affect the strain hardening; It does not happen often.

In one specific example, an aluminum alloy suitable for forming the oxide layer described herein may be a cast aluminum alloy. In general, cast aluminum alloys can be distinguished by a four to five digit number as described with the break point. The numbers in the hundred place refer to alloying elements, while the numbers after the dividing point refer to shapes (casting forms or ingots). For example, the cast alloy may be an x1xx.x series containing at least 99% aluminum; X2xx.x series containing copper; X3xx.x series including silicon, copper and / or magnesium; X4xx.x series containing silicon; X5xx.x series containing magnesium; X7xx.x series containing zinc; X8xx.x series containing annotations; X9xx.x series containing various metals. Suitable machined aluminum alloys can be, but are not limited to, 355, 356, 357, 360, 380, 319, and the like.

In one specific example, the aluminum alloy suitable for forming the oxide layer described herein may be a known aluminum alloy. The above-mentioned known aluminum alloys include Al-Li alloys (alloys of aluminum and lithium), Duralumin (alloys of aluminum and copper), Nambe (alloys of aluminum and other seven unexplained metals), Magnox (alloys of aluminum and magnesium ), Zamak (an alloy of aluminum, zinc, magnesium and copper), Silumin (an alloy of aluminum and silicon), and AA-8000. The anodizing method described herein generally can include at least three processing steps, for example, pre-processing, anodizing and post-processing. Any pretreatment process known to those skilled in the art can be used to pretreat the surface of the aluminum substrate prior to the anodizing step. Suitable pretreatment processes include surface treatment by surface cleaning by mechanical and / or chemical means, corona discharge, flame, plasma, alkaline and / or acid etching, and combinations thereof But is not limited thereto. In some specific examples, the surface of the aluminum substrate may be washed first, then chemically treated, or etched. The cleaning can be done by known mechanical means, chemical means or a combination thereof. To remove oil and particulates on the surface, a solvent is used in a degreasing process and mechanical stirring or ultrasound vibration

but is not limited to, using ultrasonic vibration.

Optionally, the cleaned surface can be chemically treated with a non-etched alkaline solution continuously at a preferably high temperature to further remove contaminants. In addition, the cleaned surface can be etched by an aqueous solution comprising inorganic acid, strong organic acid, or a combination thereof. Suitable inorganic acids include, but are not limited to, sulfuric acid, nitric acid, hydrochloric acid, hydrofluoric acid, hydrobromic acid, hydroiodic acid, phosphoric acid, and combinations thereof. Suitable strong organic acids may be, but are not limited to, p-toluenesulfonic acid, trifluoroacetic acid, 4- (trifluoromethyl) benzoic acid, methanesulfonic acid, acetic acid and combinations thereof. The etchant solution may be a metal dichromate (e.g. lithium, sodium and potassium bichromate) or a metal permanganate (e.g. lithium, sodium and potassium permanganate), peroxide (e.g. hydrogen peroxide) And combinations thereof, but are not limited thereto.

In general, various degrees of etching (e.g., weak, medium, and high) can be controlled by varying the time and temperature of the etching process. The etch time may vary from about 1 minute to 4 hours, from about 10 minutes to 2 hours, and from about 15 minutes to 1 hour. The etch temperature may range from about 20 ° C to 90 ° C, from about 25 ° C to 80 ° C, from about 30 ° C to 75 ° C, or from about 30 ° C to 60 ° C. The degree of etching can generally be increased by increasing the etching time, increasing the etching temperature, or a combination thereof.

In one specific example, the surface of the aluminum substrate may be pretreated by a Forest Product Laboratories (FPL) etching process. The FPL process generally comprises the following steps:

1) removing oil and fine particles using a solvent such as a hydrocarbon and a halogenated hydrocarbon (e.g., trichlorethylene);

2) an alkaline cleaning step to further remove contaminants by infiltrating the aluminum substrate into the non-etch alkali solution at 50 [deg.] F to 140 [deg.] F;

3) immersing the aluminum substrate in an aqueous solution of sulfuric acid and sodium dichromate for 9-15 minutes to etch;

4) washing the aluminum substrate with water at 50 DEG C or lower for about 1-2 minutes;

5) Drying step in which the aluminum substrate is air-dried at less than 65 ° C for one hour.

In another specific example, the surface of the aluminum substrate may be pretreated by a phosphoric acid anodize (PAA) etch process. The PAA etch process is generally referred to as FPL etch process, except that the PAA etch process includes an anodizing process that applies a bias of about 10 V through a stainless steel anode to form an excellent anode layer in the product. .

Optionally, the surface of the aluminum substrate may be brightened by pretreating the surface with a concentrated mixture of phosphoric acid and nitric acid, which chemically polishes the surface of the aluminum. In some specific examples, near mirror finishing can be created.

In the anodizing step, the aluminum substrate may be impregnated with a bath containing an electrolyte, while an electric current may pass through the bath to form an oxide layer on the surface of the aluminum substrate. The oxide layer is mainly derived from the aluminum substrate itself, and is not derived from the electrolyte. Depending on the aluminum substrate, the oxide layer may be transparent,

It may be opaque or colored. Moreover, the oxide layer may be dyed simultaneously or sequentially with one or more suitable colors suitable for various decorative and / or protective purposes.

The water-soluble electrolyte generally contains water, sulfuric acid and oxlic acid. Any commercially available sulfuric acid can be used. The amount of the sulfuric acid may be about 100 g to 360 g, about 140 g to 220 g, and about 160 g to 200 g, per liter of the electrolyte. Any commercially available oxalic acid may be used. remind

The amount of oxalic acid may be about 5 g to 40 g, about 12 g to 20 g, and about 14 g to 18 g per liter of electrolyte. In some specific examples, the electrolyte may comprise about 160 grams to 200 grams of sulfuric acid per liter of electrolyte, about 14 grams to 18 grams of oxalic acid per liter of electrolyte.

Alternatively, the electrolyte may additionally include aluminum ions, metal sulfates, organic acids other than oxalic acid, metal carboxylates, or combinations thereof. In one specific example, the electrolyte may comprise aluminum ions. The amount of the aluminum ion may be about 0.5 g to 30 g, about 1 g to 20 g, or 2 g to 11 g per liter of the electrolyte. In another specific example, the electrolyte may comprise metal sulfates, metal salts of organic acids or organic acids other than oxalic acid. The amount of each of the metal sulfate, the organic acid, and the metal carboxylate may be 0 to 100 g per 1 liter of electrolyte. In one specific example, the electrolyte may be substantially free of metal sulfates, organic acids other than oxalic acid, or metal carboxylates.

Wherein the metal sulfate is selected from the group consisting of lithium, sodium, potassium, copper, magnesium, manganese, silicon, zinc, iron, chromium, vanadium, titanium, bismuth, gallium, tin, lead, zirconium, nickel, cobalt, But are not limited to, sulfate of the combination. Suitable examples of such organic acids include saturated aliphatic alpha-hydroxy mono

Saturated and unsaturated aliphatic dicarboxylic acids (e.g., malonic acid, succinic acid and maleic acid) other than saturated aliphatic alpha-hydroxy monocarboxylic acids (e.g., glycolic acid, lactic acid and malic acid) and oxalic acid. But is not limited to. The metal of the metal carboxylate may be lithium, sodium, potassium, copper, magnesium, manganese, silicon, zinc, iron, chromium, vanadium, titanium, bismuth, gallium, tin, lead, zirconium, nickel or cobalt. The carboxylate may be derived from saturated and unsaturated aliphatic dicarboxylic acids, including saturated aliphatic monocarboxylic acids, saturated aliphatic alpha-hydroxymonocarboxylic acids and oxalic acids, or combinations thereof.

The temperature of the anodizing bath may be from about 5 ° C to 25 ° C or from about 10 ° C to 15 ° C. Wherein the anodizing step is performed at a first current density of less than 0.8 A / dm2, less than 0.7 A / dm2, less than 0.6 A / dm2, or less than 0.5 A / dm2 in the first period, dm 2 to 2.5 A / dm 2, about 1.6 A / dm 2 to 2.4 A / dm 2, about 1.7 A / dm

2 to 2.3 A / dm < 2 >. The first period may be from about 0 to 10 hours, and may be from about 0.5 minutes to about 5 hours or from about 1 minute to about 1 hour. The second period may be from about 1 minute to about 5 hours, from about 5 minutes to about 1.5 hours, or from about 5 minutes to about 45 minutes. The anodizing step may be performed in a third period of from about 0.5 A / dm2 to about 2.0 A / dm2

From about 0.75 A / dm2 to about 1.75 A / dm2, or from about 1.0 A / dm2 to about 1.5 A / dm2

Lt; RTI ID = 0.0 > current density < / RTI > The third period

From about 1 minute to about 5 hours, from about 1 minute to about 2 hours, or from about 1 minute to about 30 minutes.

In order to maintain the current density of the specific range, it is necessary to gradually increase the applied voltage between the electrodes from about 10 V to 250 V, depending on the thickness of the oxide layer formed on the aluminum substrate. In one specific example, the applied voltage may be increased from about 10 V to about 200 V, from about 15 V to about 150 V, from about 20 V to about 100 V, to maintain the current density at a constant or specific range. The anodizing step described herein may be performed using a constant direct current or a pulsed direct current, a rectified pulsed direct current, an alternating current, a rectified alternative current, A combination of these can be used

have.

Alternatively, the electrolyte may be stirred or cooled by a stirring device or a cooling device to remove heat formed on the surface of the aluminum substrate during the anodizing step. Efficient adjustment of the electrolyte temperature can generally stabilize the coating quality and improve the physical properties of the coating. In some specific examples,

The apparatus can be, for example, a mechanical mixing device such as a stirrer, a mixer and a homogenizer or an ultrasonic vibrator or a mixer capable of promoting the circulation of electrolytes around the surface of an aluminum substrate have.

In another specific example, the stirring apparatus may include one or more stirring tubes having holes having a diameter of about 5 to 50 microns (mu m), about 10 to 40 microns, or about 15 to 25 microns. Air can pass through the holes and very fine air bubbles can be formed on or near the surface of the aluminum substrate. The air bubble

Thermal energy generated on the surface of the anode substrate can be transferred to a relatively cool electrolyte. In the post-treatment step, the porous anode oxide layer may be dyed or colored, sealed, polished or a combination thereof. In some preferred embodiments, the oxide layer may be dyed prior to sealing to form a dye layer thereon. Here, inorganic and organic dyes or coloring agents suitable for dyeing or coloring the anode oxide layer can be used. Fig. 1 shows the pores 2 of the anode cell 1 of the anode oxide present on the aluminum substrate 3. Fig. In one specific example, the diameter of the pores may be from 0.005 to about 0.05 microns or from 0.01 to about 0.03 microns.

In another specific example, the particle size of the dyeing or coloring molecules may be from about 5 nm to 60 nm or from 15 nm to 30 nm. The dyeing or staining may be carried out by any dyeing or coloring method known to those skilled in the art which allows the coloring agent or dye to enter or accumulate in the pores of the anode cell to form a dye layer.

Some organic and inorganic dyes are disclosed, for example, in " Anodizing and Coloring of Aluminum Alloys "by S. Kawai ASM International (2002), incorporated herein by reference. Organic dyes include acid dyes, acid metal complexes dyes, acid medium dyes, direct dyes, week acid dyes, disperse dyes, But are not limited to, solvent dyes such as dissolved red dyes, active dyes, alkaline dyes and dyes dissolved in alcohol, dyes dissolved in oil, and the like . The inorganic dyes are listed in Table 2 below, but are not limited thereto. The colors which can be obtained from the inorganic dyes are also given in the following Table 2. In general, dyeing or coloring can be achieved by one of the following methods. In electrolytic coloring after anodizing, the product can be impregnated into an electrolyte bath containing an inorganic metal salt. Thereafter, a metal salt can be accumulated at the base of the anode cell gap by applying a current. The colors that appear are generally dependent on the metals used and the processing conditions. Moreover, the range of colors can be extended by over-coloring with organic dyes. Suitable metals include, but are not limited to, tin, cobalt, nickel, and copper.

Integral coloring can be achieved by combining anodizing and coloring and simultaneously coloring the oxide cell walls with different colors and shapes such as bronze and black shades. In general, integral coloring is more resistant to abrasion than conventional anodizing. This can be one of the most costly processes because it requires significantly more power.

Organic dyes can be used to make various colors. Organic dyes can provide intense and intense colors that may not be consistent with other paint systems that are commonly used. In general, they can provide excellent weather fastness and light fastness. The range of colors can be extended by over dyeing electrolyte colors with organic dyes for a wider range of colors and shades. This method is relatively inexpensive and may include a minimum of initial capital than any other coloring process.

Interfernce coloring may include a modification of the pore structure produced in an electrolyte containing sulfuric acid. Pore expansion can occur at the pore base. The accumulation of metals at these locations is due to the large number of light-resistant colors ranging from blue, green, and yellow to red

a light-fast color can be produced. The colors are generally induced by optical interference effects rather than by light scattering, as in the basic electrolyte coloration process.

In some specific examples, organic dyes may be used to fill the pores of the anode oxide layer with color. In another specific example, the inorganic dye or metal salt may be electrochemically deposited at the base of the void to produce a broad spectrum of colors. In another specific example, the metal (e. G., Tin) is electrically connected to the pores of the anode oxide layer

It can accumulate and provide color. In one specific example, the color may be formed either internally or internally with the oxide layer, by adding a predetermined organic acid to the sulfur electrolyte during the anodizing process and using a pulse current. The color of the oxide layer is selected from the group consisting of red, orange, yellow, green, blue, indigo, purple, pink, silver, gold, bronze, brown, black, gray, pale champagne, white and all known shades and hues (tint), but is not limited thereto.

After dyeing, the surface of the oxide layer may optionally be sealed by methods known to those skilled in the art in sealing the anode oxide layer. Typically, the pores are closed in the anode cell through a seal, thereby providing resistance to staining, abrasion, craze and color degradation on the surface. Moreover, sealing can reduce or eliminate smearing and can increase corrosion resistance. In some specific examples, the sealing may be accomplished by infiltration in a salt consisting of a nickel salt, a cobalt salt, and combinations thereof at 20 ° C, through which the void can be closed with a salt. In another specific example, the seal is hot water or

And converting the oxide into its hydrate form using steam. This conversion can reduce the size of the pores of the anode cell and also reduce the pores of the surface as the oxide expands. In another specific example, the sealing may be carried out in the presence of a metal dichromate such as sodium bichromate. In one specific example

The sealing may be carried out in the presence of a metal acetate such as nickel acetate or other anti-bloom agent.

After sealing, the surface of the oxide layer may optionally be polished or buffed by a polishing or buffing process known to those skilled in the art. In one specific example, the surface of the oxide layer may be buffed or polished by a buffing or polishing compound. The buffing or polishing compound may generally comprise abrasive particles, a binder and optional additives. The buffing or polishing compound may be a marble

diluent particles such as marble, gypsum, flint, silica, iron oxide, aluminum silicate and glass (including glass bubbles and glass beads) may additionally be included. The buffing or polishing compound may be in the form of a cake, tube, paste, or liquid. Glossy compounds or buffing compounds may include, but are not limited to, Opaline gloss compounds from Rhone-Poluenc Co., France and Tripoli compounds from Formax Manufacturing Corp., Grand Rapids, MI .

Known conventional abrasive particles can be used for buffing or polishing the compound. Suitable abrasive particles may include fused aluminum oxide (including fused alumina, heat treated aluminum oxide and brown aluminum oxide), silicon carbide (including green silicon carbide), boron carbide, titanium carbide, diamond, May be cubic boron nitride, garnet, tripoli (microcrystalline SiO2), chromium oxide, cerium oxide, molten alumina-zirconia, sol-gel-derived abrasive particles and combinations thereof , But is not limited thereto. Any conventional buffing compound binder can be used to buff or gloss the compound. Suitable binders include, but are not limited to, natural waxes, synthetic waxes, chlorinated waxes such as tetrachloronaphthalene, pentachloronaphthalene and polyvinyl chloride, and combinations thereof.

Conventional known abrasive additives may be used to buff or gloss the compound.

Suitable additives include pigments such as titanium dioxide or iron oxide, emulsifiers

an emulsifier, a surfactant, a wetting gent, a foam stabilizer

but are not limited to, foam stabilizers, heat or UV stabilizers, antioxidants, grinding aids, and combinations thereof. The grinding aid may be an organic halide such as sodium chloride, potassium cryolite, sodium cryolite, ammonium cryolite, potassium tetrafluoroborate, sodium tetrafluoroborate, silicon fluoride, potassium chloride and magnesium chloride. An organic halide compound, a halide salt.

In some specific examples, the buffing may be via a rotating buff wheel filled with a buffing compound in contact with the surface of the article. In another specific example, the buffing can consist of two steps, for example cutting and coloring. The cutting step may be a pre-treatment step carried out by broadly cutting the abrasive buffing compound. For example, the cutting step may be a step necessary to ensure a desired surface machining or smoothness. The coloring step may generally include light-duty buffing to make the surface of the article glossy.

Alternatively, coloring compounds may be used. Certain coloring compounds can be formulated with a thinner mesh size abrasive than that used in the buffing compound in the cutting step. In one preferred specific example, the same double-duty buffing compound can be used in both the cutting and coloring stages.

In some specific examples, the buffing compound may be in liquid or paste form. The abrasive particles and binders used to formulate with liquid or paste buffing compounds may be the same as those generally used in solid buffing compounds. The components of the liquid or paste buffing compound may be aqueous based and spray < RTI ID = 0.0 > and /

And may be made of an emulsified fluid to be applied in a rush form.

In one preferred specific example, the buffing may be via the buffing wheel. Buffing wheels generally perform two primary functions. The first is to transport the abrasive particles to the surface of the article to perform cutting and / or coloring. The second, if necessary, can flow plastically or generate sufficient frictional heat to shine the surface of the product. Buffing wheels suitable for polishing or buffing processes may be within the design, buffing structure and design range known to those skilled in the art.

In another specific example, the surface of the oxide layer may be polished by an abrasive product such as abrasive slurry, abrasive compound or known abrasive fine wheel or abrasive paper. In some specific examples, the surface of the oxide layer is coated on the wrapping film

by a conventional known fine-finishing product such as a lapping film,

Can be pinged. In one specific example, the wrapping film may comprise an abrasive article of 400 grit or finer size. In one specific example, the surface of the oxide layer has an Ra value of less than 0.1 microns, less than 0.09 microns, less than 0.08 microns, less than 0.07 microns, less than 0.06 microns, less than 0.05 microns, less than 0.04 microns, less than 0.03 microns, less than 0.02 microns Or less than 0.01 microns. The flatness of the surface can be measured by the following profilometry method.

The surface roughness of the oxide layer can be measured by Talysurf PGI 1240 Aspherics Measuring System of Taylor Hobson, Leicester, UK. The gage distance may be about 10 mm, about 5 mm, about 1 mm, about 0.5 mm, about 0.25 mm, or about 0.1 mm on a straight line. The probe speed for the measurement may be about 5 mm / s, about 1 mm / s, about 0.5 mm / s, about 0.25 mm / s, or about 0.1 mm / s.

In one specific example, the oxide layer has a microhardness measured by the method described herein of about 280 to 1000 Hv, about 280 to 750 Hv, about 300 to 550 Hv, about 320 to 520 Hv, or about 320 to 500 Hv. In one specific example, the microhardness can be measured by a Buehler Micromet 2103 having a Vickers diameter (square base) indenter with a 136 degree angle.

In one specific example, the microhardness can be measured by conventional microhardness measurements known to those skilled in the art.

In some specific examples, the oxide layer may be from about 15 microns to 100 microns, from about 15 microns to 75 microns, from about 15 microns to 50 microns, from about 15 microns to 40 microns, or from about 15 microns to 30 microns. In one specific example, the thickness can be measured by a Fisher Isoscope MP30E coating thickness tester.

The method described herein can be used for batch anodizing and can be used for continuous coil anodizing. Batch anodizing can generally include racking parts and can infiltrate them into a series of treatment tanks. Parts suitable for batch anodizing are extrusion, sheet or bent metal parts (bent

but are not limited to, metal parts, castings, cookware, cosmetic cases, flashlight bodies, and machined aluminum parts.

Continuous coil anodizing typically involves continuously loosening a coil that has already been wound through a series of anodizing, etching, and tank cleaning, and then rewinding the vessel and structural anodized coil. Such methods include bulky sheets, foils and lighting fixtures, reflectors,

It can be suitably used for non-finished products such as louvers, spacer bars for insulating glass and continuous roofing systems.

Example

While the present invention has been described in detail with reference to the following examples, these examples should not be construed as limiting the scope of the present invention.

Example 1

Example 1 was prepared by anodizing an aluminum alloy Al-6063 article in an electrolyte bath containing water, sulfuric acid (180 g per liter of electrolyte) and oxalic acid (electrolyte 16 g / liter) at a temperature of about 10-16 ° C. This anodizing process consisted of four successive steps, each with different current densities and electrolysis times. First stage

The current density of the system was 0 to 0.7 A / dm < 2 > for 10 minutes. The current density in the second step was 0.7 to about 2.0 A / dm < 2 > for 10 minutes. The current density in the third step was 2.0 to 2.5 A / dm < 2 > for 10 minutes. The current density in the fourth step was 1.5 A / dm 2 for 50 minutes. The current density was generated by a pulsed direct current with a voltage potential of about 20V to 24V. The first, second and third pulse current sequences were turned on for 0.8 seconds and turned off for 0.2 seconds. The fourth pulse current sequence was turned on for 0.6 seconds and turned off for 0.4 seconds.

Example 2

Example 2 was prepared similarly to the procedure of Example 1 except that the product was dyed blue.

Example 3

Example 3 was prepared similarly to the procedure of Example 1, except that the product was dyed red.

Comparative Example A

The aluminum alloy Al-6063 in an electrolyte bath containing water and sulfuric acid (180-200 g per liter of electrolyte) at a temperature of about 24 ° C, a current density of about 12-22 V and a current density of about 1.0 A / dm

2 under the conditions of Comparative Example A

Respectively.

Comparative Example B

Comparative Example B was prepared by anodizing for 45-60 minutes under the conditions of Comparative Example B-2.

Comparative Example C

Comparative Example C was prepared by coating an aluminum alloy Al-6063 article with diamond-like carbon using physical vapor deposition techniques. This process lasted 2-2.5 hours. The thickness of the diamond-like carbon coating was about 1 micron. The interface was chrome.

Comparative Example D (Type 2 anodizing)

The aluminum alloy Al-6063 in an electrolytic bath containing water and sulfuric acid (190-200 g per liter of electrolyte) at a temperature of about 18-20 ° C, a current density of about 15-17V and a current density of about 1.5 A / dm

2 for 45-60 minutes to give Comparative Example D

.

Wear test

The abrasion resistance of Comparative Example A-C and Example 1 was tested. The abrasion test was carried out with a Taber Abrasive Wearing tester according to the ISO 5470-1 process using a CS-17 polishing head orientation under a loading condition of 1 kg. The abrasion test was carried out at 40 rpm with suction on.

As mentioned above, specific examples of the present invention provide various methods for producing colored oxide layers for application in decorative applications. Although the invention has been described in terms of a relatively limited number of embodiments, the specific features shown in one embodiment do not affect other embodiments of the invention. In some specific examples, methods
May include a number of steps not mentioned herein. In another embodiment, the method does not include the steps not listed here or there may be substantially no steps not listed. The method of producing the colored oxide layer described herein is described with reference to a number of steps. These steps can be performed in any order
Can also be executed. One or more steps may be omitted or combined, but still achieve substantially the same result. The appended claims are intended to cover all such modifications and changes as fall within the true spirit and scope of the invention.
All publications and patent applications mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. While the foregoing invention has been described in some detail by way of specific description and examples for purposes of clarity of understanding, those skilled in the art,
It will be apparent that the invention may be varied and modified without departing from the scope or spirit of the invention.

Claims

A method of making a colored oxide layer on an aluminum substrate,
(a) disposing an aluminum substrate as an anode in an electrolyte including water, oxalic acid and sulfuric acid; And
(b) a first current of less than 0.8 A / dm < 2 >
Anodizing and then anodizing to a second current having a density of from 1.5 A / dm 2 to 2.5 A / dm 2 to produce an oxide layer.

The aluminum substrate according to claim 1, wherein the aluminum substrate has a density of 1.0 A / dm 2 to 1.5 A / dm 2
Lt; RTI ID = 0.0 > of: < / RTI >

3. The method of claim 2, wherein the first current, the second current and the third current are each independently generated by a constant direct current or a pulsed direct current. Gt;

2. The method of claim 1, wherein the method further comprises agitating the electrolyte through a gitation device.

5. The method of claim 4, wherein the agitating device comprises a stirring tube.

2. The method of claim 1, further comprising forming a dye layer over the oxide layer.

The method of claim 1, wherein the electrolyte further comprises an aluminum ion, a metal sulfate, an organic acid, or a combination thereof.

2. The method of claim 1, wherein the electrolyte further comprises from 2 g to 11 g of aluminum ions per liter of electrolyte.

The method of claim 1, wherein the electrolyte comprises from 5g to 40g of oxalic acid per liter of electrolyte and from 100g to 360g of sulfuric acid per liter of electrolyte.

10. The method of claim 9, wherein the electrolyte comprises from about 12 g to about 20 g of oxalic acid per liter of electrolyte and from about 140 g to about 220 g of sulfuric acid per liter of electrolyte.

11. The method of claim 10, wherein the electrolyte comprises from 14g to 18g of oxalic acid per liter of electrolyte and from 160g to 200g of sulfuric acid per liter of electrolyte.

The method of claim 1, wherein the anodizing step is performed at a temperature of from 5 캜 to 25 캜.

13. The method of claim 12, wherein the anodizing step is performed at a temperature between 10 < 0 > C and 15 < 0 > C.

The method of claim 1, wherein the method further comprises polishing the surface of the oxide layer so that the Ra value is less than 0.1 micron.

An article comprising an aluminum substrate having a colored oxide layer on the aluminum substrate
the colored oxide layer comprising: (a) disposing an aluminum substrate into an anode in an electrolyte comprising water, oxalic acid and sulfuric acid; And (b) density
Anodizing the aluminum substrate for 1 minute to 1 hour at a first current of less than 0.8 A / dm < 2 > and then anodizing to a second current having a density of 1.5 A / dm2 to 2.5 A / dm <&Lt; RTI ID = 0.0 > and / or < / RTI >

16. The article of claim 15, wherein the colored oxide layer has a microhardness of 280 to 1000 Hv.

16. The article of claim 15, wherein the colored oxide layer is 15 microns to 50 microns in thickness.

16. The method of claim 15 wherein said aluminum substrate is selected from the group consisting of aluminum and optionally silicon, boron, germanium, arsenic, antimony, tellurium, copper, magnesium, manganese, zinc, lithium, iron, chromium, vanadium, titanium, bismuth, , Lead, zirconium, nickel, cobalt, and combinations thereof.

16. The article of claim 15, further comprising a dye layer on the oxide layer.

16. The article of claim 15, wherein the surface of the colored oxide layer has an Ra value between 0.01 and 0.1 micron.