US3669856A - Process for the production of colored protective coatings on articles of aluminum or aluminum alloys - Google Patents

Process for the production of colored protective coatings on articles of aluminum or aluminum alloys Download PDF

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US3669856A
US3669856A US835668A US3669856DA US3669856A US 3669856 A US3669856 A US 3669856A US 835668 A US835668 A US 835668A US 3669856D A US3669856D A US 3669856DA US 3669856 A US3669856 A US 3669856A
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aluminum
alternating
voltage
alternating voltage
asymmetrical
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US835668A
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Ove Christopher Gedde
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Priority claimed from NO245968A external-priority patent/NO117398B/no
Priority claimed from NO332968A external-priority patent/NO119560B/no
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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
    • C25D11/02—Anodisation
    • C25D11/04—Anodisation of aluminium or alloys based thereon
    • C25D11/18—After-treatment, e.g. pore-sealing
    • C25D11/20—Electrolytic after-treatment
    • C25D11/22—Electrolytic after-treatment for colouring layers
    • 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

Definitions

  • the asymmetrical voltage may be 3,418,222 12/1968 Schaedel ..204/58 produced, for example by Supplying two or more alternating 1 6O 5/1968 A Sada "204/58 voltages of different amplitude, frequency and/or phase, or by L978 9/1960 D 'ckson et 204/58 using a direct voltage superimposed on the alternating voltage. 2,951,025 8/1960 Mostovych et al. ..204/58 2,935,454 5/1960 Tokumoto ..204/45 7 Claims, 4 Drawing Figures PROCESS FOR THE PRODUCTION OF COLORED PROTECTIVE COATINGS ON ARTICLES OF ALUMINUM OR ALUMINUM ALLOYS BACKGROUND OF THE INVENTION 1.
  • the present invention relates to a process for the production of colored protective coatings on articles of aluminum or aluminum alloys which have previously been provided with a protective oxide layer.
  • Processes have also been developed for simultaneous anodizing and coloring of aluminum articles. With these processes only a limited selection of colors is obtainable. The processes are expensive and difficult to carry out, and very rigid requirements are made for the working and heat-treatment of the aluminum articles, as the metallic structure therein is of the utmost importance for the result obtained. The processes also demand the use of large currents and high voltages and a long time, and they are relatively expensive.
  • aluminum articles which have already been provided with an oxide layer may be provided with a further, opaque, white, protective layer by electrolytic treatment of the article with alternating current or direct current in an aqueous bath containing dissolved titanium salts.
  • the deposited, opaque film may then be colored with organic dyes in aqueous or organic solvents. The process is expensive and cumbersome.
  • British Pat. specification No. 1,022,927 relates to a process for the production of colored, protective coatings on articles of aluminum or aluminum alloys by passing an alternating current through an aqueous bath containing a salt yielding a colored metal oxide or hydroxide between a previously oxidized article of aluminum or aluminum alloy and a counterelectrode of carbon, carborundum or aluminum.
  • This process is limited to the use of particular counter-electrodes in order to obtain the colored coatings, and the process has little flexibility as regards the obtainable color tones.
  • the present invention thus provides a process for the production of colored protective coatings on articles of aluminum or aluminum alloys by passing an alternating current between a previously anodically oxidized aluminum article and a counter-electrode immersed in an acid aqueous bath containing salts of metals capable of coloring the alumina layer, and the process is characterized in that the alternating voltage supplied is modulated as regards its amplitude and/or frequency so as to make it asymmetrical thereby to control the color tone on the aluminum article.
  • the modulation of the alternating voltage can be carried out in several ways, e.g., by simultaneously supplying two or more different alternating voltages or a superimposed direct voltage or by generating an alternating voltage having the desired frequency and curve shape.
  • stainless steel or titanium are preferably used because they are practically insoluble in the acid bath used for the coloring and because they lead to an advantageously low energy consumption.
  • metal salts in the oxide layer of the aluminum article is due to deposition and dissolution of metal at the surface of the aluminum article caused by the alternating current as the current changes its direction, however, in such a manner that some of the metal forms chemical compounds with other substances, e.g., oxygen, sulphur, hydroxyl groups or other groups, and remains in the pores of the aluminum oxide layer.
  • the strength of the alternating voltage and the modulation of the amplitude and/or frequency thereof according to the present process is from 5 to 50 volts dependent upon the composition of the electrolyte and the properties of the oxide layer previously formed.
  • a current density of 0.1 to 0.5 A/dm dependent upon the electrolyte employed, and a low treatment period of 1 to 10 minutes.
  • FIG. la schematically shows a circuit diagram which can be used to modulate the applied alternating voltage according to the present process
  • FIG. lb shows the curve of a such modulated alternating voltage
  • FlG.2a shows an alternative embodiment of a circuit diagram which can be used for supplying a modulated alternating voltage in the present process
  • FIG. 2b shows one form of the curve of an alternating voltage modulated by using the circuit of FIG. 2a.
  • FIG. 1 S and S are two oppositely directed rectifiers coupled in parallel relationship with regard to one another, each rectifier being connected in series with a rheostatR and R Substantially the same circuit diagram as in FIG. 1 is shown in FIG. 2, however, here two controlled rectifiers T and T are used. These are arranged such that in a controllable manner they can be respectively used to disrupt the current in a part of each of the positive and negative half periods of the alternating current. It is then possible to omit the rheostats shown in FIG. 1, and there is obtained a control of the two currents in respectively positive and negative direction through the electrolysis bath essentially without any energy losses.
  • the circuits are provided with an ammeter A in series with each rectifier and with two voltmeters V connected in series respectively with oppositely directed rectifiers corresponding in direction with the rectifiers S and S or T, and T
  • the circuits shown can be used for voltages of from to 200 volts, preferably 0 to 50 volts, for current strengths of from 0 to 10,000 A, preferably 0 to 1,000 A, and for a frequency of 5 to 500 cycles per second, preferably 50 cycles per second.
  • controlled rectifiers As used herein is meant such rectifiers which can be made current carrying by the use of an auxiliary potential which is synchronous with the main voltage, i.e., thyristors.
  • thyristors By the use of two such thyristors in parallel it is possible in a controllable manner to cut off a part of the positive and negative half waves of the alternating current. Thus, it is possible to regulate the effective value of the two half waves.
  • EXAMPLE 1 An aluminum article with a previously oxidized surface was immersed in an aqueous bath containing 2.0 percent sulphuric acid, 7 percent aluminum sulphate and 1.5 percent copper sulphate. An electrode of stainless steel was used as a counterelectrode.
  • Alternating current was passed through the electrolyte at a voltage of 20 volts between the aluminum article to be colored and the counter-electrode.
  • the current density was 0.4 Aldm
  • the applied alternating voltage was made asymmetrical from two different A.C. sources applied simultaneously and having different phases in such a manner that the total negative half wave of the alternating voltage with regard to the aluminum was greater than the positive one. A deep red color was obtained in 10 minutes.
  • EXAMPLE 2 A previously oxidized aluminum article, the same counterelectrode and the same electrolyte as in Example 1 were used.
  • the alternating current was now supplied in such a manner that the positive half wave of the alternating voltage was greater than the negative one.
  • Example 1 The coloring was carried out in the same time and with the same voltage and current density as in Example 1. There was obtained a red color which was less intense than the color obtained in Example 1.
  • EXAMPLE 3 An aluminum article which had previously been anodically oxidized in aqueous sulphuric acid was immersed in an electrolyte containing 1.5 percent boric acid and 1 percent cadmium sulphate. A lead electrode was used as a counter-electrode.
  • a symmetrical alternating voltage was supplied to the aluminum article to be coated and to the counter-electrode.
  • the alternating voltage was then modulated so as to make its negative half wave greater with regard to the lead electrode than its positive half wave.
  • the alternating voltage was made asymmetrical by superimposing thereon a rectified alternating voltage.
  • the current strength remained substantially constant, and a deep, black color was obtained on the aluminum.
  • the current density used was adjusted with regard to the alumina layer and was 0.4 A/dm. if too high current densities are used the previously formed oxide layer on the aluminum will be damaged.
  • the treatment period was 10 minutes.
  • EXAMPLE 4 An aluminum article which had previously been anodically oxidized in aqueous sulphuric acid was treated in the same electrolyte as in Example 3, and the same counter-electrode, alternating voltage and current density were used.
  • EXAMPLE 5 An aluminum article which had previously been anodically oxidized was used in an electrolyte together with a counterelectrode as described in Example 3. The same alternating voltage and current density were also used. The alternating voltage supplied was modulated from the beginning so as to be asymmetrical, and after a treatment period of 10 minutes there was obtained a beige color on the aluminum article.
  • the aluminum articles colored by using the present process have proven to possess a coating which is very resistant to abrasion and atmospheric influence.
  • the color tone of the aluminum article can also be varied within a very broad range of color tones, and the necessary time for obtaining a colored coating which is very resistant towards abrasion and atmospheric influence can be kept very short. There is thereby obtained a considerable saving both as regards labor and ener gy consumption.
  • the coloring takes place faster and more efficiently if the alternating voltage is regulated relatively slowly, of the order of a few seconds, from zero to the voltage which is decided for the coloring. This relates both to the starting up of the coloring and to a later supply of another alternating voltage than the one initially used.
  • a process for the production of colored, protective coatings on articles of aluminum or aluminum alloys comprising passing an alternating current between an electrode system comprising a previously anodically oxidized aluminum article and a counter-electrode immersed in an acid aqueous bath containing salts of metals capable of coloring the aluminum oxide layer, the improvement wherein an alternating voltage with controlled asymmetry is applied to the electrodes whereby to control the color tone of the aluminum article, the alternating voltage having been made asymmetrical by modulating the alternating voltage externally of said electrode system.
  • a process as claimed in claim 1, wherein the asymmetrical voltage is produced by supplying at least two alternating voltages of different amplitude, frequency and/or phase.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Engineering & Computer Science (AREA)
  • Other Surface Treatments For Metallic Materials (AREA)
  • Application Of Or Painting With Fluid Materials (AREA)
  • Chemical Treatment Of Metals (AREA)
  • Photoreceptors In Electrophotography (AREA)
  • Electrochemical Coating By Surface Reaction (AREA)
  • Detergent Compositions (AREA)
US835668A 1968-06-21 1969-06-23 Process for the production of colored protective coatings on articles of aluminum or aluminum alloys Expired - Lifetime US3669856A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NO245968A NO117398B (enrdf_load_stackoverflow) 1968-06-21 1968-06-21
NO332968A NO119560B (enrdf_load_stackoverflow) 1968-08-27 1968-08-27

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US (1) US3669856A (enrdf_load_stackoverflow)
JP (1) JPS4934287B1 (enrdf_load_stackoverflow)
AT (1) AT285272B (enrdf_load_stackoverflow)
BE (1) BE734886A (enrdf_load_stackoverflow)
CH (1) CH520206A (enrdf_load_stackoverflow)
DE (2) DE1902983C3 (enrdf_load_stackoverflow)
DK (1) DK126210B (enrdf_load_stackoverflow)
ES (1) ES368153A1 (enrdf_load_stackoverflow)
FI (1) FI47385C (enrdf_load_stackoverflow)
FR (1) FR2011376A1 (enrdf_load_stackoverflow)
GB (1) GB1257047A (enrdf_load_stackoverflow)
NL (1) NL152304B (enrdf_load_stackoverflow)
SE (1) SE351440B (enrdf_load_stackoverflow)

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4975433A (enrdf_load_stackoverflow) * 1972-11-21 1974-07-22
US3878056A (en) * 1973-08-24 1975-04-15 Sumitomo Chemical Co Process for electrolytic coloring of the anodic oxide film on a aluminum or aluminum base alloys
JPS50109144A (enrdf_load_stackoverflow) * 1974-02-07 1975-08-28
US3909367A (en) * 1973-02-23 1975-09-30 Pechiney Aluminium Method for creating a polychrome motif on an object made of aluminum or aluminum alloy
US3929593A (en) * 1973-09-21 1975-12-30 Riken Light Metal Ind Company Method of forming colored oxide film on aluminum or aluminum alloy material
US3930966A (en) * 1974-03-20 1976-01-06 Riken Light Metal Industries Company, Ltd. Method of forming colored oxide film on aluminum or aluminum alloy
US3977948A (en) * 1974-02-20 1976-08-31 Iongraf, S.A. Process for coloring, by electrolysis, an anodized aluminum or aluminum alloy piece
US4179342A (en) * 1978-06-28 1979-12-18 Reynolds Metals Company Coating system method for coloring aluminum
US4180443A (en) * 1978-06-28 1979-12-25 Reynolds Metals Company Method for coloring aluminum
WO1980000158A1 (en) * 1978-06-28 1980-02-07 Reynolds Metals Co Coating system
US4526671A (en) * 1982-09-24 1985-07-02 Pilot Man-Nen-Hitsu Kabushiki Kaisha Surface treatment of aluminum or aluminum alloys
EP0254190A1 (de) * 1986-07-23 1988-01-27 Henkel Kommanditgesellschaft auf Aktien Verfahren und Schaltungsanordnungen zur elektrolytischen Einfärbung anodisierter Aluminiumoberflächen
US4931151A (en) * 1989-04-11 1990-06-05 Novamax Technologies Holdings Inc. Method for two step electrolytic coloring of anodized aluminum
US5899709A (en) * 1992-04-07 1999-05-04 Semiconductor Energy Laboratory Co., Ltd. Method for forming a semiconductor device using anodic oxidation
WO2008061555A1 (en) * 2006-11-23 2008-05-29 Anox B.V. Process for providing aluminium cookware with a copper coating
US20100307924A1 (en) * 2007-09-20 2010-12-09 Heid Guenter Power control device of a power network of an electrochemical coating facility

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4948824B1 (enrdf_load_stackoverflow) * 1970-03-18 1974-12-24
US3769180A (en) * 1971-12-29 1973-10-30 O Gedde Process for electrolytically coloring previously anodized aluminum using alternating current
GB1434701A (en) * 1974-02-20 1976-05-05 Alcan Res & Dev Process and apparatus for electrolytic colouration of anodised aluminium
ES437604A1 (es) * 1975-05-12 1977-01-16 Empresa Nacional Aluminio Sistema de autocontrol y regulacion del valor medio de la tension aplicada en procesos de coloracion electrolitica de aluminio anodizado.
ES474736A1 (es) * 1978-10-31 1979-04-01 Empresa Nacional Aluminio Sistema de generacion y autocontrol de la forma de onda y - tension o corriente aplicable a procesos de coloracion elec-trolitica del aluminio anodizado.
JPS55158298A (en) * 1979-05-30 1980-12-09 Fuji Photo Film Co Ltd Manufacture of support for lithographic plate
ES482210A0 (es) * 1979-07-04 1982-08-01 Proceso para la coloracion electrolitica del aluminio a-nodizado.
ES8103205A1 (es) * 1980-04-22 1981-02-16 Empresa Nacional Aluminio Proceso para colorear electroliticamente el aluminio y sus aleaciones
DE3743113A1 (de) * 1987-12-18 1989-06-29 Gartner & Co J Verfahren zum elektrolytischen faerben von anodisch erzeugten oxidschichten auf aluminium und aluminiumlegierungen

Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2231373A (en) * 1935-01-08 1941-02-11 Firm Ematal Electrochemical Co Coating of articles of aluminum or aluminum alloys
DE741753C (de) * 1940-04-13 1943-11-17 Langbein Pfanhauser Werke Ag Verfahren zur elektrolytischen Faerbung von Gegenstaenden aus Aluminium mit oxydischer Oberflaechenschicht
US2443599A (en) * 1942-05-04 1948-06-22 Poor & Co Electroplating method employing pulsating current of adjustable wave form
US2901412A (en) * 1955-12-09 1959-08-25 Reynolds Metals Co Apparatus for anodizing aluminum surfaces
US2935454A (en) * 1953-05-01 1960-05-03 Tokumoto Shin-Ichi Method of the electrodeposition of titanium metal
US2951025A (en) * 1957-06-13 1960-08-30 Reynolds Metals Co Apparatus for anodizing aluminum
US2951978A (en) * 1957-05-29 1960-09-06 Thor P Ulvestad Reverse pulse generator
CA662063A (en) * 1963-04-30 Asada Tahei Process for inorganically coloring aluminium
US3382160A (en) * 1960-03-31 1968-05-07 Asada Tahei Process for inorganically coloring aluminum
US3418222A (en) * 1966-02-28 1968-12-24 Murdock Inc Aluminum anodizing method

Patent Citations (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CA662063A (en) * 1963-04-30 Asada Tahei Process for inorganically coloring aluminium
US2231373A (en) * 1935-01-08 1941-02-11 Firm Ematal Electrochemical Co Coating of articles of aluminum or aluminum alloys
DE741753C (de) * 1940-04-13 1943-11-17 Langbein Pfanhauser Werke Ag Verfahren zur elektrolytischen Faerbung von Gegenstaenden aus Aluminium mit oxydischer Oberflaechenschicht
US2443599A (en) * 1942-05-04 1948-06-22 Poor & Co Electroplating method employing pulsating current of adjustable wave form
US2935454A (en) * 1953-05-01 1960-05-03 Tokumoto Shin-Ichi Method of the electrodeposition of titanium metal
US2901412A (en) * 1955-12-09 1959-08-25 Reynolds Metals Co Apparatus for anodizing aluminum surfaces
US2951978A (en) * 1957-05-29 1960-09-06 Thor P Ulvestad Reverse pulse generator
US2951025A (en) * 1957-06-13 1960-08-30 Reynolds Metals Co Apparatus for anodizing aluminum
US3382160A (en) * 1960-03-31 1968-05-07 Asada Tahei Process for inorganically coloring aluminum
US3418222A (en) * 1966-02-28 1968-12-24 Murdock Inc Aluminum anodizing method

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4975433A (enrdf_load_stackoverflow) * 1972-11-21 1974-07-22
US3909367A (en) * 1973-02-23 1975-09-30 Pechiney Aluminium Method for creating a polychrome motif on an object made of aluminum or aluminum alloy
US3878056A (en) * 1973-08-24 1975-04-15 Sumitomo Chemical Co Process for electrolytic coloring of the anodic oxide film on a aluminum or aluminum base alloys
US3929593A (en) * 1973-09-21 1975-12-30 Riken Light Metal Ind Company Method of forming colored oxide film on aluminum or aluminum alloy material
JPS50109144A (enrdf_load_stackoverflow) * 1974-02-07 1975-08-28
US3977948A (en) * 1974-02-20 1976-08-31 Iongraf, S.A. Process for coloring, by electrolysis, an anodized aluminum or aluminum alloy piece
US3930966A (en) * 1974-03-20 1976-01-06 Riken Light Metal Industries Company, Ltd. Method of forming colored oxide film on aluminum or aluminum alloy
US4180443A (en) * 1978-06-28 1979-12-25 Reynolds Metals Company Method for coloring aluminum
US4179342A (en) * 1978-06-28 1979-12-18 Reynolds Metals Company Coating system method for coloring aluminum
WO1980000158A1 (en) * 1978-06-28 1980-02-07 Reynolds Metals Co Coating system
US4526671A (en) * 1982-09-24 1985-07-02 Pilot Man-Nen-Hitsu Kabushiki Kaisha Surface treatment of aluminum or aluminum alloys
EP0254190A1 (de) * 1986-07-23 1988-01-27 Henkel Kommanditgesellschaft auf Aktien Verfahren und Schaltungsanordnungen zur elektrolytischen Einfärbung anodisierter Aluminiumoberflächen
US4992155A (en) * 1986-07-23 1991-02-12 Henkel Kommanditgesellschaft Auf Aktien Circuitry for the electrolytic coloring of anodized aluminum surfaces
US4931151A (en) * 1989-04-11 1990-06-05 Novamax Technologies Holdings Inc. Method for two step electrolytic coloring of anodized aluminum
US5899709A (en) * 1992-04-07 1999-05-04 Semiconductor Energy Laboratory Co., Ltd. Method for forming a semiconductor device using anodic oxidation
WO2008061555A1 (en) * 2006-11-23 2008-05-29 Anox B.V. Process for providing aluminium cookware with a copper coating
US20100143622A1 (en) * 2006-11-23 2010-06-10 Anox B.V. Process for providing aluminium cookware with a copper coating
US20100307924A1 (en) * 2007-09-20 2010-12-09 Heid Guenter Power control device of a power network of an electrochemical coating facility

Also Published As

Publication number Publication date
DE1902983B2 (de) 1973-03-22
FI47385C (fi) 1973-11-12
AT285272B (de) 1970-10-27
DE1902983A1 (de) 1970-02-05
DE1902983C3 (de) 1978-06-22
DE1930288B2 (de) 1972-12-28
FI47385B (enrdf_load_stackoverflow) 1973-07-31
ES368153A1 (es) 1971-05-01
FR2011376A1 (enrdf_load_stackoverflow) 1970-02-27
JPS4934287B1 (enrdf_load_stackoverflow) 1974-09-13
NL6909024A (enrdf_load_stackoverflow) 1969-12-23
CH520206A (de) 1972-03-15
DE1930288A1 (de) 1970-05-27
NL152304B (nl) 1977-02-15
BE734886A (enrdf_load_stackoverflow) 1969-12-01
SE351440B (enrdf_load_stackoverflow) 1972-11-27
DK126210B (da) 1973-06-18
GB1257047A (enrdf_load_stackoverflow) 1971-12-15

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