US3692640A - Continuous anodic oxidation method for aluminum and alloys thereof - Google Patents

Continuous anodic oxidation method for aluminum and alloys thereof Download PDF

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Publication number
US3692640A
US3692640A US72022A US3692640DA US3692640A US 3692640 A US3692640 A US 3692640A US 72022 A US72022 A US 72022A US 3692640D A US3692640D A US 3692640DA US 3692640 A US3692640 A US 3692640A
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United States
Prior art keywords
aluminum
anodic oxidation
electrolyte
cathode
liquid
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Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
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US72022A
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English (en)
Inventor
Takeshi Hamabe
Takashi Suzuki
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Panasonic Holdings Corp
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Matsushita Electric Industrial Co Ltd
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Filing date
Publication date
Priority claimed from JP7560569A external-priority patent/JPS496978B1/ja
Priority claimed from JP11225169U external-priority patent/JPS4914734Y1/ja
Priority claimed from JP9965969A external-priority patent/JPS496979B1/ja
Priority claimed from JP9966069A external-priority patent/JPS496980B1/ja
Priority claimed from JP11820369U external-priority patent/JPS514265Y1/ja
Priority claimed from JP11820169U external-priority patent/JPS49899Y1/ja
Application filed by Matsushita Electric Industrial Co Ltd filed Critical Matsushita Electric Industrial Co Ltd
Application granted granted Critical
Publication of US3692640A publication Critical patent/US3692640A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/005—Apparatus specially adapted for electrolytic conversion coating
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D11/00—Electrolytic coating by surface reaction, i.e. forming conversion layers
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/06—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used
    • C25D11/08—Anodisation of aluminium or alloys based thereon characterised by the electrolytes used containing inorganic acids

Definitions

  • the present invention relates to a method and apparatus for continuously oxidizing by anodic oxidation the surface of elongate articles consisting of aluminum or an aluminum alloy (hereinafter referred to as aluminum as a whole), i.e. aluminum foils, aluminum strips, aluminum wires, etc.
  • the heat generated in the anodic oxidation is attributed to the heat generated by the reaction between aluminum and oxygen, and the Joule heat generated during the passage of a current through the oxide film, electrolyte, cathode and aluminum.
  • the heat generated is substantially entirely transferred to the electrolyte in the electrolytic cell and, therefore, the temperature of the electrolytic system can be maintained constant, by cooling the electrolyte.
  • the current density at which the anodic oxidation is conducted becoming higher and higher, such a method is not capable of sufficiently cooling the electrolysis system and non-uniform temperature distribution will result.
  • a current density higher than a certain value yellowing of the film occurs, making it impossible to obtain a normal oxide film. This is because the intensity and uniformity of stirring of the electrolyte undergo a certain limitation.
  • the present invention consists in an anodic oxidation method which is proposed with a view to obviating the above-described problems, and in which the socalled electrolytic cell with a predetermined quantity of electrolyte stored therein, as used heretofore, is not used and hence the electrolytic portion can be sufiiciently cooled, providing for a high current density anodic oxidation at high efficiency.
  • the anodic oxidation method according to the present invention is adapted for continuous oxidation of the entire area of at least one side surface of an elongate article of aluminum, basically by passing the article continuously in opposed relation to a cathode device.
  • the cathode device is composed of a hollow container which is provided with inlet ports for continuously feeding an electrolyte therein and has a cathode therein.
  • One side of the hollow container is open and covered with a liquidpermeable material.
  • the elongate article of aluminum is passed in front of the liquid-permeable material, with a predetermined interval therebetween, or is passed in contact with the same.
  • the space between the liquidpermeable material and the elongate article of aluminum is filled with the electrolyte which has been fed into the hollow container through the inlet ports and uniformalized in liquid pressure by the liquid-permeable material during passage therethrough.
  • the space between the cathode and the liquid-permeable material interior of the cathode device is of course filled with the electrolyte. Therefore, the cathode and the elongate article of aluminum are electrically connected by the electrolyte through the liquid-permeable material.
  • a voltage is impressed on the cathode and the elongate article of aluminum under such condition, whereby the surface of the aluminum is oxidized by anodic oxidation.
  • FIG. 1 is a cross-sectional view illustrating an embodiment of the present invention
  • FIG. 2 is a cross-sectional view illustrating another embodiment of the invention.
  • FIG. 3 is a cross-sectional view illustrating still another embodiment of the invention, in which a plurality of the electrolytic units shown in FIG. 1 and cooling sections are arranged alternately;
  • FIG. 4 is a perspective view, partially in section, of another form of the cathode device shown in 'FIG. 1;
  • FIGS. 5 and 6 are perspective views of still other forms of the cathode device, which are adapted for the anodic oxidation of aluminum wires, respectively.
  • electrolytic unit for practicing the method of this invention.
  • electrolytic unit refers to a unit by which anodic oxidation is effected and which includes aluminum to be oxidized, a cathode device and an electrolyte.
  • reference numeral 1 designates inlet ports through which the electrolyte is continuously fed into the cathode device by a pump 10 or from a tank (not shown) disposed above said cathode device.
  • Reference numeral 2 designates a cathodeconstituting electrode plate and a lead 3 thereof is connected to one terminal of an anodic oxidation power source (not shown).
  • Reference numeral 4 designates the electrolyte filling the interior of the cathode device
  • 5 designates a liquid-permeable material constituting one side of the cathode device.
  • the liquid-permeable membrane 5 serves as a discharge port 6 for the electrolyte.
  • Reference numeral 7 indicates the electrolyte discharged from the cathode device through the liquid-permeable material 5, which constantly fills the space formed between an aluminum 8 to be treated and the cathode device.
  • the cathode device is composed of the inlet ports 1 for the electrolyte, the cathode 2 and the liquid-permeable material constituting the discharge port for the electrolyte.
  • the electrolyte first flows into the cathode device through the inlet ports 1 as indicated by the arrows and then towards the discharge port 6 to be discharged from the cathode device through the liquid-permeable material 5.
  • the aluminum 8 to be treated is continuously passed in front of the liquid-permeable material 5 in the direction of the arrow or in an opposite direction, with a predetermined interval therebetween. Therefore, the electrolyte 7 discharged through the liquid-permeable material 5 flows down along the surface of the aluminum. As a result, a current flows between the cathode and the aluminum through the electrolyte and the surface of the aluminum is oxidized by anodic oxidation.
  • the apparatus of FIG. 1 is adapted for anodic oxidation of only one side surface of the aluminum. Where both side surfaces of the aluminum are desired to be oxidized by anodic oxidation, this can be attained simply by providing another apparatus of the same construction on the opposite side of the aluminum.
  • liquid-permeable material which covers the discharge port for electrolyte
  • an acid-resistant metal screen an ethylene tetrafluride fabric or a polypropylene fabric is suitably used.
  • the mesh of the liquid-permeable material is selected case by case within the range of 0.01-1 mm., in relation with the desired rate of discharge of the electrolyte.
  • FIG. 2 In cross-section, reference numeral 11 designates the cathode devices by which both surfaces are oxidized by anodic oxidation respectively and each of which forms an electrolytic unit together with the aluminum 8 and the electrolyte 7.
  • Reference numeral 12 designates a cooling liquid poured onto the surface of the aluminum opposite to the surface being subjected to anodic oxidation, to cool the electrolytic unit.
  • one or a plurality of the cathode devices are provided on one side of the aluminum where only one side of the aluminum is desired to be oxidized, or on each side of the aluminum where both sides of the aluminum are desired to be oxidized.
  • the cooling liquid is poured at each electrolytic unit.
  • the second method is to provide the electrolytic units and the cooling units alternately for the purposes of enhancing the cooling effect of the electrolytic units and forming cracks in the oxide films formed by anodic oxidation.
  • This arrangement is shown in FIG. 3 in cross-section.
  • reference numeral 11 designates the cathode devices
  • 14 the cooling units for ejecting a cooling liquid against the aluminum 8 to cool the latter
  • 4 the electrolyte in the respective cathode devices.
  • the cooling liquid serves, not only to cool the aluminum but also to form cracks in the oxide films formed. Namely, by rapidly cooling the surfaces of the aluminum which is heated to an of cracks formed, and oxide films excelling in flexibility can be obtained.
  • the third method is to create an electrolyte temperature difference between adjacent ones of two or more electrolytic units provided along the direction of travel of the aluminum, for the purpose of forming cracks in the oxide films formed on the surfaces of the aluminum.
  • electrolysis a large amount of heat is gen erated on the surfaces of the aluminum being subjected to electrolysis, and hence the aluminum substrate and the oxide films formed thereon are elevated to a considerably high temperature. If, in this case, a temperature difference is created in the electrolyte in the respective electrolytic units, cracks are formed in the oxide films due to thermal stress. These cracks are useful for improving the flexibility of the oxide films.
  • FIG. 4 is a perspective view, partially shown in section, of a cathode device which is particularly advantageous in providing a uniform current distribution in the treatment of a band-shaped aluminum.
  • reference numeral 22 designates a cathode, 1 inlet ports for feeding the electrolyte into the cathode device therethrough, 5 the liquid-permeable material covering the discharge port of the cathode device, 8 a band-shaped aluminum to be treated, 21 an insulating material constituting a part of the cathode device, and 25 a liquid-permeable material for further enhancing the uniformity of current distribution in both vertical and horizontal directions.
  • the width of the cathode is equal to or smaller than the width of the aluminum to be treated and the vertical length thereof is shorter than the vertical length of the electrolyte discharge port.
  • the front surface of the cathode is corrugated, so as to increase the effective area thereof.
  • On the inside or outside of the liquid-permeable material at the electrolyte discharge port of the cathode device are provided the other liquid-permeable material for contact with the longitudinally spaced edge portions and the opposite edge portons of the aluminum, so as to avoid concentration of current to the longitudinal and transverse edges of the aluminum due to the edge effect of electric current.
  • FIG. 5 and 6 are perspective views of cathode devices respectively which are most adapted for anodic oxidation of aluminum wires.
  • the cathode device shown in a double-walled cylindrical body having an inner wall consisting of a liquid-permeable material 5 and an outer wall consisting of a metal plate 2 which constitutes a cathode.
  • the inner and outer walls are connected at the upper and lower edges thereof by annular metal plates which serve as cathode, or other material as at 20, so as to define an annular space between the inner and outer walls, and electrolyte inlet ports 1 are provided on the upper annular plate 20.
  • An electrolyte introduced into the cathode device through the inlet ports 1 is ejected towards an aluminum wire 8 to be treated, through the liquid-permeable material 5.
  • the aluminum wire 8 is oxidized by anodic oxidation, while continuously moving in the direction of the arrow.
  • the electrolyte 7 is continuously ejected through the liquid-permeable material 5 and drops down under gravity, so that the heat is removed from the electrolytic unit highly efficiently.
  • the ring shape of the cathode is advantageous is providing a uniform electric field for the aluminum wire, and makes a great contribution to the improvement in uniformity of the oxide film formed.
  • FIG. 6 there is shown a cathode device of the same type as that of FIG. 5 but the inner wall thereof consists of the metal plate or other material and the outer wall thereof consists of the liquid-permeable material.
  • Aluminum wires 8 are oxidized by anodic oxidation during their passage along the surface of the liquid-permeable material.
  • EXAMPLE 1 charge port The interval between the aluminum strip and the cathode was 5 mm.
  • a 30 weight percent sulfuric acid solution was used as electrolyte and the temperature thereof was maintained at 30 C. by a cooling device.
  • the electrolyte was supplied into the cathode device at the rate of 40 l./min.
  • the anodic oxidation was carried out at a current density of 200 a./dm. by continuously conducting a quantity of electricity at the rate of 0.5 ah./dm. As a result, a uniform oxide film having a thickness of 6.3 1. was formed over the entire area of both surfaces of the aluminum strip.
  • EXAMPLE 2 A continuous anodic oxidation was conducted, using the method illustrated in FIG. 2.
  • the aluminum strip, the cathode and the electrolyte used were the same as those mentioned in Example 1.
  • the sulfuric acid solution used as the electrolyte was concurrently used as the cooling liquid at the same temperature.
  • the cooling liquid discharge port was formed in a rectangular shape so that it may be ejected uniformly against each side of the aluminum strip.
  • the direct current was supplied to give a quantity of electricity at the rate of 0.5 ah./dm. and the current density was varied from 200 to 600 a./dm.
  • An excellent oxide film having a thickness of 6.3 and a dielectric breakdown voltage of 220 v. A.C. was formed by anodic oxidation in the current density range up to 560 a./dm.
  • EXAMPLE 3 An anodic oxidation of an aluminum wire having a diameter of 0.6 mm. was carried out continuously, using the cathode device shown in FIG. 5. Lead was used for the cathode and a polypropylene fabric was used for the liquid permeable material at the electrolyte discharge port. The inner diameter of the cathode device was 15 mm. and the outer diameter thereof was 80 mm. An electrolyte consisting of 30 weight percent sulfuric acid solution was supplied to the cathode device by means of a pump, and the temperature thereof was maintained at 30 C. The anodic oxidation was conducted at the supply rate of a quantity of electricity of 0.5 ah./dm. and a current density of 600 a./dm. and a uniform, excellent oxide film having a thickness of 8 was obtained.
  • an oxide film of improved flexibility can be obtained because cracks can be formed in the film only by the anodic oxidation treatment.
  • the present invention is of great industrial advantage.
  • a continuous anodic oxidation method for aluminum comprising continuously feeding a sulfuric acid solution into a device consisting of a hollow container having a cathode, at least one inlet port, a discharge port, and a liquid-permeable material covering said discharge port, through said inlet port and discharging the same from said discharge port through said liquid-permeable material at a rate of about 0.67 1./cm. /cm. /min.: passing bandor rod-shaped aluminum along the surface of said liquid-permeable material in opposed relation thereof; and impressing a voltage across said cathode and said aluminum at a current density of about 200600 amps/ m? at about 30 C., whereby the surface of said aluminum is oxidized by anodic oxidation.
  • a continuous anodic oxidation method for aluminum according to claim 1 wherein said device is provided on one side of said aluminum band and cooling liquid is poured onto the surface of the aluminum band opposite to the surface of same facing said device.
  • a continuous anodic oxidation method for aluminum according to the method of claim 1 wherein two of said devices are provided, one on each side of said aluminum band at points removed from each other so that said two devices are not opposed to each other.
  • a continuous anodic oxidation method for aluminum as defined in claim 1, wherein a plurality of said devices and a plurality of cooling liquid pouring devices are arranged alternately on at least one side of the aluminum along the direction of travel of the aluminum.
  • a continuous anodic oxidation method for aluminum as defined in claim 1, wherein at least one device which discharges the electrolyte at a relatively high temperature and at least one cathode device which discharges the electrolyte at a relatively low temperature are alternately arranged along the direction of travel of the aluminum.
  • a continuous anodic oxidation method for aluminum according to claim 1 wherein said discharge port is in the side of said container and said bandor rod-shaped aluminum is passed vertically along the surface of said liquid-permeable material in opposed relation thereto.
  • liquid-permeable material is an acidresistant metal screen, an ethylene tetrafluride fabric or a polypropylene fabric having a mesh size of from 0.01 to 1 mm.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
  • Fuel Cell (AREA)
  • Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
  • Printing Plates And Materials Therefor (AREA)
US72022A 1969-09-18 1970-09-14 Continuous anodic oxidation method for aluminum and alloys thereof Expired - Lifetime US3692640A (en)

Applications Claiming Priority (7)

Application Number Priority Date Filing Date Title
JP7560569A JPS496978B1 (ja) 1969-09-18 1969-09-18
JP11225169U JPS4914734Y1 (ja) 1969-11-25 1969-11-25
JP9965969A JPS496979B1 (ja) 1969-12-09 1969-12-09
JP9966069A JPS496980B1 (ja) 1969-12-09 1969-12-09
JP11821069 1969-12-11
JP11820369U JPS514265Y1 (ja) 1969-12-11 1969-12-11
JP11820169U JPS49899Y1 (ja) 1969-12-11 1969-12-11

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US3692640A true US3692640A (en) 1972-09-19

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US72022A Expired - Lifetime US3692640A (en) 1969-09-18 1970-09-14 Continuous anodic oxidation method for aluminum and alloys thereof

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US (1) US3692640A (ja)
CH (1) CH561785A5 (ja)
DE (1) DE2045787C3 (ja)
FR (1) FR2061788B1 (ja)
GB (1) GB1327263A (ja)
NL (1) NL7013791A (ja)

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3873318A (en) * 1972-06-08 1975-03-25 Alcan Res & Dev Production of lithographic plates
US3909387A (en) * 1971-04-01 1975-09-30 Sigmund Bereday Apparatus for producing polymer-coated aluminum products
US4059494A (en) * 1974-11-19 1977-11-22 Sumitomo Aluminum Smelting Co., Ltd. Process for continuous electrolytic coloring of aluminum or aluminum base alloy strip and wire
US4225399A (en) * 1979-04-25 1980-09-30 Setsuo Tomita High speed aluminum anodizing
US4367125A (en) * 1979-03-21 1983-01-04 Republic Steel Corporation Apparatus and method for plating metallic strip
US4397727A (en) * 1981-03-17 1983-08-09 Rasselstein Ag Device for electrodepositing a single-sided metal coating onto a metal strip, especially onto steel strip
US4401523A (en) * 1980-12-18 1983-08-30 Republic Steel Corporation Apparatus and method for plating metallic strip
US4469565A (en) * 1982-08-05 1984-09-04 Andritz-Ruthner Industrieanlagen Aktiengesellschaft Process of continuously electrodepositing on strip metal on one or both sides
US4605480A (en) * 1983-06-13 1986-08-12 Hoechst Aktiengesellschaft Device for continuously anodically oxidizing aluminum strips on one surface thereof and use of these aluminum strips in the production of offset printing plates
US20140241011A1 (en) * 2011-10-19 2014-08-28 Sumitomo Electric Industries, Ltd. Reactor, converter, and power converter apparatus

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2540602A (en) * 1946-07-03 1951-02-06 Lockheed Aircraft Corp Method and apparatus for the surface treatment of metals
FR1215921A (fr) * 1957-11-26 1960-04-21 Aluminium Lab Ltd Procédé et appareil pour la fabrication de revêtements anodiques sur aluminium
US3038850A (en) * 1958-03-17 1962-06-12 Olin Mathieson Aluminum anodizing apparatus

Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3909387A (en) * 1971-04-01 1975-09-30 Sigmund Bereday Apparatus for producing polymer-coated aluminum products
US3873318A (en) * 1972-06-08 1975-03-25 Alcan Res & Dev Production of lithographic plates
US4059494A (en) * 1974-11-19 1977-11-22 Sumitomo Aluminum Smelting Co., Ltd. Process for continuous electrolytic coloring of aluminum or aluminum base alloy strip and wire
US4367125A (en) * 1979-03-21 1983-01-04 Republic Steel Corporation Apparatus and method for plating metallic strip
US4225399A (en) * 1979-04-25 1980-09-30 Setsuo Tomita High speed aluminum anodizing
US4401523A (en) * 1980-12-18 1983-08-30 Republic Steel Corporation Apparatus and method for plating metallic strip
US4397727A (en) * 1981-03-17 1983-08-09 Rasselstein Ag Device for electrodepositing a single-sided metal coating onto a metal strip, especially onto steel strip
US4469565A (en) * 1982-08-05 1984-09-04 Andritz-Ruthner Industrieanlagen Aktiengesellschaft Process of continuously electrodepositing on strip metal on one or both sides
US4605480A (en) * 1983-06-13 1986-08-12 Hoechst Aktiengesellschaft Device for continuously anodically oxidizing aluminum strips on one surface thereof and use of these aluminum strips in the production of offset printing plates
US20140241011A1 (en) * 2011-10-19 2014-08-28 Sumitomo Electric Industries, Ltd. Reactor, converter, and power converter apparatus

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Publication number Publication date
CH561785A5 (ja) 1975-05-15
NL7013791A (ja) 1971-03-22
FR2061788B1 (ja) 1974-08-23
DE2045787B2 (de) 1976-04-08
FR2061788A1 (ja) 1971-06-25
GB1327263A (en) 1973-08-22
DE2045787C3 (de) 1982-03-18
DE2045787A1 (de) 1971-04-08

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