US3359190A - One-side anodizing of aluminum sheet - Google Patents

One-side anodizing of aluminum sheet Download PDF

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US3359190A
US3359190A US342451A US34245164A US3359190A US 3359190 A US3359190 A US 3359190A US 342451 A US342451 A US 342451A US 34245164 A US34245164 A US 34245164A US 3359190 A US3359190 A US 3359190A
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sheet
electrolyte
anodizing
strip
liquid
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US342451A
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Cooke William Ernest
Helwigh Niels Otto
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Alcan Research and Development Ltd
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Aluminium Laboratories Ltd
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Priority to NL129563D priority Critical patent/NL129563C/xx
Priority to GB1055001D priority patent/GB1055001A/en
Application filed by Aluminium Laboratories Ltd filed Critical Aluminium Laboratories Ltd
Priority to US342451A priority patent/US3359190A/en
Priority to DE1965A0048228 priority patent/DE1496713B1/de
Priority to FR3545A priority patent/FR1424643A/fr
Priority to NL6501359A priority patent/NL6501359A/xx
Priority to SE01428/65A priority patent/SE326352B/xx
Priority to NO156638A priority patent/NO115611B/no
Priority to BE659263A priority patent/BE659263A/xx
Application granted granted Critical
Publication of US3359190A publication Critical patent/US3359190A/en
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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
    • 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
    • C25D11/024—Anodisation under pulsed or modulated current or potential
    • 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
    • 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
    • C25D11/24—Chemical after-treatment
    • C25D11/246—Chemical after-treatment for sealing layers

Definitions

  • a method for continuous production of a porous anodic coating on one side only of aluminum sheet embraces advancing the sheet in submerged relation to aqueous bodies of liquid on opposite sides while said liquids are maintained in turbulent flow and anodizing current is passed from the sheet through the liquid on one side, at least said latter liquid being an anodizing electrolyte.
  • the temperatures of the bodies of liquid are maintained at sutliciently high values for thermally conditioning the sheet and coating in a manner found necessary to prevent impairment, e.g. crazing, of the coating on subsequent high temperature sealing.
  • Anodizing current is upwards of 100 amperes per square foot and the liquid is controlled to maintain the temperatures of the flowing bodies at sufficiently high values, of which the sum is greater than 100 C., for the stated thermal conditioning, an exemplified operation being to maintain both liquids at 65 C.
  • the non-anodizing liquid is preferably an identical electrolyte, e.g. sulfuric acid solution, and current can be conducted to the sheet through the non-anodizing liquid, or from electrode structure in a preceding electrolyte-filled chamber through which the sheet first passes, the latter method also permitting use of alternating current for one-side anodizing.
  • This invention relates to the production of anodic coatings or films on aluminum, the term aluminum being employed to include aluminum base alloys which, like pure aluminum, are susceptible of being anodized to produce porous type oxide films. More particularly, the invention is directed to continuous anodizing of aluminum sheet, to produce an anodic coating on one side of such sheet in a rapid and continuous manner, especially with reference to coatings in the range of thickness of 0.1 mil and upwards, and preferably in reference to such coatings which are of porous type, e.g. as produced with sulfuric acid or equivalent electrolytes.
  • aluminum sheet elongated aluminum pieces or material having considerable width relative to its thickness, whether designated as sheet, strip, plate, foil or the like, the method being particularly advantageous for aluminum sheet in strip form that can be coiled and withdrawn continuously from the coil through an anodizing bath, to be re-wound in coil form either before or after further treatment.
  • the invention is predicated on the discovery of certain new conditions or combinations of condition which cooperate in an unusual manner for the rapid attainment, in continuous operation, of a highly satisfactory anodic coating on one side of aluminum sheet material, being advantageously a porous type coating which, especially in contrast to certain very thin films of one micron or less (including certain barrier type films), has a thickness as above, of about 0.1 mil or more, and notably in such range up to 2 mils.
  • Such anodic coating is effectively durable and adherent under many circumstances, and is adapted to serve a wide variety of finishing or protective purposes, as generally known for anodic coatings. As will be understood, these uses include protection against corrosion, wear, electrical breakdown, or other deteriorating influences, as well as the provision of 7 colored surfaces by dyeing or pigmenting the anodic film.
  • oxide films, coatings or layers i.e. aluminum oxide, although it is recognized that this is only the major component in anodic coatings.
  • the present improvements are concerned with production of a coating on one side only, of the aluminum strip. Such operation, and the resulting product, are eminently useful for many purposes, and indeed may be preferred or necessary for certain situations where aluminum sheet is employed. Furthermore, wherever a single anodized surface is adequate or desirable, there is corresponding saving in production, particularly with respect to the electrical energy required to the consumed in the electrolytic anodizing reaction.
  • the present procedure affords relatively high speed continuous operation, whereby unusually large current densities may be employed to achieve coatings, of desired quality and thickness (including substantial'thicknesses upwards of 0.5 mil, e.g. of the order of one mil), without diificulties or deterioration experienced in prior elforts to obtain such results.
  • a further, specific problem that was found to arise in high-speed, one-side continuous anodizing was in maintaining the desired characteristics of the film during and after subsequent treatments such as scaling in hot water or hot aqueous solutions.
  • a special feature of the invention involves the discovery of procedure, particularly conditions, that effectively eliminate the tendency of the porous-type anodic coatings, formed as just described, to deteriorate, e.g. to craze, upon subsequent high temperature sealing or the like.
  • the present method involves the continuous advance of the sheet through, and in effect, in submergence in aqueous electrolyte as contained in an appropriate elongated tank or vessel arranged to hold electrolyte to a level above the passing sheet.
  • Th electrolyte is in fact arranged in two bodies, completely or at least substantially separate from each other and respectively in contact with opposite sides of the sheet, an unusually convenient arrangement being for disposition of the sheet in a horizontal position, so that the mutually isolated electrolyte bodies are respectively above and below it, although other arrangements, such as a vertical disposition of the sheet or strip, can be employed, and although in some cases (as explained below) one of the aqueous bodies here described as electrolytes may not serve an electrolytic function.
  • an unusually effective operation for continuously anodizing a passing aluminum surface comprises maintaining the electrolyte in turbulent flow over such surface, the flow being in a direction longitudinal of the path of the moving surface, the turbulence being substantially uniform across the surface, and the chief critical feature being that the flow is turbulent as distinguished from the kind usually called streamlined or laminar. Operation in the foregoing manner with turbulent flow has been found highly efficacious in achieving certain temperature conditions that are a basic part of the present one-side anodizing process.
  • each electrode can consist of a plate (or an array of coplanar elements) of the conductive material, such as lead, parallel to the strip and having a plane surface of an area substantially equal to and coextensive with the adjacent exposed surface of the strip.
  • the spacing of each electrode from the strip surface may advantageously be such as will coact in affording the desired character of electrolyte flow along the surface of the strip.
  • the electrode on one side constitutes the cathode (being connected to the negative terminal of the source of power), so that current passes from the strip through the electrolyte to the cathode and accomplishes the anodizing action at the exposed surface of the strip.
  • the other electrode is disposed in the body of electrolyte on the opposite side of the strip, and serves as anode for the complete cell thus formed, i.e. so that current from the positive terminal of the source enters the second body of electrolyte from the abovementioned anode and passes to the strip, to render the latter anodic for the anodizing action.
  • temperature control of the opposite sides of the strip i.e. the surface where the anodic film is forming and the opposite bare metal surface
  • cont-r01 being realized by maintaining the temperatures of the electrolytes (moving along such surfaces) at values selected in accordance with principles that have now been discovered and that are believed to be critical for the new results desired.
  • the temperatures of the electrolytes should be maintained at values such that as measured in degrees Centigrade, the sum of the electrolyte temperatures on the two sides is at least about 100 C.
  • the invention embraces the further condition that on neither side should the temperature be less than about 20 C., especially as a matter of practicality in operation. Indeed special efficiency seems to be attained where the liquid on each side is in the range of 40 C. and above, with the selected temperature on at least one of the sides at a sulficiently higher value so that the sum of the temperature is greater than 100 C.
  • a particularly convenient mode of operation is to control the liquid temperature so that it is the same on both sides, e.g. then within a range on each side of about 50 C. and upwards, it being found that distinctly optimum results (having regard to other aspects of the anodizing treatment as Well) are achieved with each electrolyte, passing the sheet, at a temperature of about 65 C.
  • an acute problem was found to occur in high speed one-side operation, utilizing current densities of the order of 1'00 amperes per square foot, and preferably at least several hundred amperes per square foot, and also utilizing the arrangement (specially appropriate for such high current densities) of the submergence of both sides of the work in contact with rapidly traveling electrolyte.
  • the difficulty is overcome by appropriate maintenance of the electrolyte temperatures at values selected in accordance with the above requirements, being values which presumably coact (from both sides of the sheet) in attaining the required conditions of the film for avoidance of adverse effects on subsequent high temperature sealing.
  • the prescribed conditions are particularly related to operations at desirably high speeds and with the relatively large current densities needed for attainment of thick coatings at such rates of travel of the work.
  • the process of the invention embracing continuous anodizing under the combination of conditions as defined, represents an improvement of significant value in the attainment of economical, continuous treatment.
  • FIG. 1 shows diagrammatically, but essentially as in vertical cross-section, an arrangement of apparatus wherein the continuous strip of aluminum is being subjected to anodization in a continuous fashion, this view also showing, as in flow sheet form, the subsequent continuous sealing of the anodized article;
  • FIG. 2 is a cross-section on line 22 of FIG. 1, of the anodizing tank
  • FIG. 3 is a view, similar to FIG. 1, of another arrangement utilizing the invention, for anodizing one side of an aluminum strip;
  • FIG. 4 is a similar view of an arrangement wherein alternating current is employed for anodic treatment in accordance with the invention.
  • the sheet to be anodized on one surface is represented by the aluminum strip 10, continuously withdrawn from the coil 11 and advanced (by suitable take-up means, mentioned below) lengthwise in a horizontal plane through the anodizing tank 12, which may be made of electrical insulating material, or lined with such material. As shown, the strip traverses the tank at a central or intermediate locality, i.e.
  • the sheet is shown as traveling through the tank 16 containing sealant liquid 18, and is finally rewound as a coil 19, providing the take-up means.
  • intermediate operations may be performed, such as washing, dyeing, pigmenting, and indeed recoiling of the strip before it is subjected to continuous traversal of the sealant.
  • FIG. 2 shows a pair of resilient bearing strips 20, 21, along opposite sides of the tank, against which the edges of the strip make contact as it passes, these rubber or like elements thus maintaining mutual isolation of the two bodies of liquid 14, 15.
  • appropriate rubber or like packing or glands 23, 24 are mounted in the end walls to provide narrow, horizontal entrance and exit slots through which .the strip may enter and leave, in liquid-tight sealed relation, thus completing the separate enclosure for the bodies of electrolyte.
  • a pair of lead or other suitable electrodes 26, 27 are mounted in submerged relation in the liquids respectively with appropriate spacing, for example one inch above and one inch below the passing strip 10, each of these being simply shown as a long flat plate having a plane face parallel to and coextensive with the corresponding exposed surface of the passing aluminum sheet.
  • suitable conductors 31 current is brought from the positive terminal of an appropriate D.C. source 30 to the lower electrode 27, and is returned via conductors 28 from the upper electrode 26 to the negative pole of the source.
  • the electrode 26 constitutes the cathode, and by flow of current from the sheet 10 through the electrolyte body 14 to the cathode, the upper surface of the sheet 10 is anodized.
  • the current path to the sheet extends from the source 30, via conductors 31 to the electrode 27, and thence through the lower body of electrolyte 15 to the sheet 10, so that the latter is anodic with respect to the upper electrolyte 14, as described above.
  • the bodies of electrolyte above and below the aluminum sheet are caused to flow over the respective sides of the latter for the desired temperature controlling function.
  • a pump 32 advances the liquid through a pipe 33 to a manifold or header 35 opening into one end of the tank 12, so that there is rapid flow of the electrolyte lengthwise of the space between the upper side of the sheet 10 and the cathode 26.
  • the liquid leaves this region through a similar manifold 36 at the opposite end of the tank and traverses a pipe 37 to return to the pump 32.
  • Means are provided for controlling or regulating the temperature of the aqueous electrolyte to maintain it at the desired value, in accordance with the conditions described above, as it traverses the surface of the aluminum sheet.
  • Such means are indicated at 38, for example in the return line 37 to the pump, and may usually consist of appropriate, conventional cooling means, thermostatically controlled.
  • Similar liquid circulating means are shown for the lower body of electrolyte 15, i.e., a pump 42, delivering liquid through pipe 43, manifold 44, then flowing rapidly between the electrode 27 and the underside of the sheet 10, for return through the manifold 46 and pipe 47.
  • Similar temperature control means 48 are included, eg. in the line 47 to the pump 42. Again, this temperature control instrumentality may be cooling means of a suitable conventional character, with appropriate thermostatic control. It may be noted that whereas the heating effect of the anodizing reaction is ordinarily such that both the anodizing electrolyte and the lower or coolant electrolyte will be required to perform a heat dissipating or cooling function even though the selected temperatures to be maintained at the surfaces of the sheet are relatively high,
  • the devices 38 and 48 may also include heating means if circumstances require. With relatively rapid fiows of electrolyte along both sides of the sheet, and appropriate avoidance of heat loss in the circulating systems, the temperature maintained in the electrolyte bodies by the instrumentalities 38, 48 will be essentially that which these liquids exhibit adjacent the surfaces of the sheet. In any event, the operation should be controlled so that, with due regard for heat losses, if any, the desired liquid temperatures are maintained along the sheet surfaces.
  • the flow be turbulent in nature, for example sufiiciently rapid under the circumstances of the fiow path, including its cross-section between the electrode and the strip, that it be turbulent rather than laminar, in accordance with established principles of flow of liquid in a conduit filled by such liquid.
  • turbulence be maintained in the electrolyte as it passes the strip, whether attained simply by selection of appropriately high velocity or with the aid of baffles or other supplemental means (not shown) of a kind conventional for promoting turbulence.
  • a liquid flow affording a number of 20,000 is satisfactorily efilcient for anodizing operation at a current density of 600 amperes per square foot, and conditions of even greater turbulence, e.g. represented by Reynolds numbers as high as 100,000, can well be used, as for very high current densities.
  • determination of a suitable flow rate for achieving turbulence and for maintaining a desired temperature in the passing liquid without more than a few degrees of rise can be made by simple preliminary tests and observations.
  • the speed of strip travel is generally governed by the thickness of film desired, having regard to the length of the anodizing path, e.g. the tank length, and the current density applied.
  • speeds of the order of 1 to 20 feet per minute are suitable, in cells from one to five feet long and with current densities at the surface being anodized, in the range of 100 amperes per square foot and above, more usually several hundred amperes per square foot.
  • very high strip speeds can be used, i.e. up to several hundred feet per minute.
  • the strip is continuously passed through the tank, and the effect of the current impressed in the manner described above, is to anodize the upper side of the strip, yielding degrees) between the lothe desired oxide coating.
  • the temperature in the rapidly flowing bodies of electrolyte on both sides is carefully maintained at a selected value, for instance preferably in the range from about 50 C. to about C.
  • the strip can thereafter be subjected to a conventional sealing operation, e.g. by passing it through the aqueous sealant 18 in the tank 16, at a temperature over 70 C., most usually well above 90 C., as for example at 98 C. to 100 C.
  • a principal function of sealing being to reduce or eliminate the ability of the film to adsorb foreign materials, and thus to improve its properties, and indeed its appearance, as against staining or the like.
  • Effective sealing action is obtained with conventional liquids, e.g. plain hot water, or slightly acidulated hot water having a pH in the conventional range of 5.5 to 6.5, or with special sealants such as sodium silicate or nickel acetate solutions.
  • an aluminum sheet 10 having any desired width, say 1 foot, can be treated by traversing it through a tank where it is in submerged contact with turbu-lently flowing bodies of electrolyte 14, 15, at opposite sides, in isolation from each other.
  • optimum electrolyte concentrations are sulfuric acid solutions of 15% strength, and on each side the traveling electrolyte is controlled, in rate and temperature, so that it enters the tank at approximately 65 C. and experiences no more than one or two degrees of rise in temperature after traversing the liquid-exposed surface of the sheet, while removing heat therefrom.
  • anodizing current density of 600 amperes per square foot of the exposed surface to be anodized (the upper surface in FIG. 1) is particularly suitable: in pilot plant operations the coulombic input required to produce an oxide film of 1 mil thickness was about 39,000 coulombs per square foot, representing a coulombic efficiency of about 87%. Under conditions of more ideal character, as where the speed of electrolyte travel is considerably above 2.5 feet per second, higher coulombic efficiencies are believed attainable, even up to 98% or 99%. This is in contrast to the approximately 70% efiiciency (54,000 coulombs per square foot) obtained from a number of prior operations in producing one mil thick films.
  • the required contact time for producing a film of a given thickness is determined by the given current density and the required coulombic input. Taking the values specified in the above example to yield a 1 mil film, the corresponding contact time is roughly one minute, so that in a cell 5 feet long the strip speed should be approximately 5 feet per minute. Under such circumstances, with the described electrolytes, the selected temperature of 65 C. can be effectively maintained and the desired turbulence can be achieved, in an electrolyte flowing at a speed of about 2.5 feet per second.
  • a flow of gallons (U.S.) of electrolyte per minute is amply turbulent and generally satisfactory.
  • the treated sheet thus carries the desired anodic, oxide coating on one side, which is found to have excellent properties, e.g. in adherence, protective effect, flexibility, high porosity, ability to be dyed, and the like. It may be appropriately sealed by treatment as described above.
  • While current densities may vary from 100 amperes per square foot to 4000 amperes per square foot, the invention is of particular significance at values of 300 amperes per square foot and above, i.e. as permitting rapid anodizing action without sacrifice of desired film thickness and characteristics. Indeed values of current density of 500 amperes per square foot and higher represent a special range of departure from anything practical or feasible in prior processes of one-side D.C. anodizing. It is normally preferred to operate in the range of 600 to 1000 amperes per square foot, although current densities up to 1500 amperes per square foot are conceived as of special value.
  • a particular feature of the invention involves the use of liquid at the opposite or bare side of the strip which is identical with the anodizing electrolyte, viz. a sulfuric acid solution of identical concentration. While in some special circumstances acid electrolytes of different concentration may be employed, or indeed the coolant on the bare side may be an electrolyte of different composition, the mechanical nature of the apparatus is such that some minor leakage or mixing of electrolytes is almost certain to occur around the lateral edges of the passing aluminum sheet. Thus under ordinary circumstances it appears that if the concentration of acid in the electrolytes differs by more than about 1% to 2%, the anodized areas near these edges tend to have at least slightly different surface characteristics from the remainder or main area of the oxide film. Differences of this sort are particularly unsatisfactory where the film is to be dyed, since the result is a band of different shade along each edge region. Likewise, if possible, the flow rates are preferably balanced along the two surfaces, to minimize leakage.
  • the strip 50 traveling horizontally, is arranged to pass first through a tank 51 and then through a main tank 52, with appropriate sealing means 53, 54, 55 at the vertical walls of the tanks, the latter conveniently having a common intermediate wall 56 which is provided with the seal 54 that the strip traverses.
  • a suitable electrode 57 of lead or other material, which provides the cathode.
  • the tank is filled with electrolyte as indicated at 58, 59', above and below the strip and in full contact with both of its faces. The electrolyte is circulated along the faces of the strip, as described above in connection with FIG.
  • FIG. 3 is purely diagrammatic and that the crosssection of the electrolyte path below as Well as above the strip 50 may be suitably limited to permit turbulent flow of electrolyte without excess volume.
  • the process effectuated in tank 52 is exactly as in FIG. 1, except that there is no electrode in the lower liquid 59.
  • the preliminary tank 51 is similarly filled with electrolyte as indicated at '64, 65, conveniently both above and below the strip, with electrodes 66, 67 disposed in the respective bodies of electrolyte and in sufficiently close proximity to the strip.
  • the electrolyte may be conveniently a sulfuric acid electrolyte, for instance identical with that employed in the tank 52 at 58 and preferably also at 59 in tank 52.
  • the electrodes 66, 67 are connected together to the positive terminal of a suitable D.C. source 68, while the negative terminal of the source is connected to the electrode 57 in the anodizing tank 52.
  • the electrolytic treatment in the preliminary tank 51 may serve a significant cleaning function, and also provides passage of current to the strip without requiring contact brushes 0r rollers.
  • the anodizing action occurs in the tank 52, i.e. by passage from the strip, which is anodic with respect to the electrolyte 58 and the cathode 57. Special cooling or temperature regulation may not be necessary in the preliminary tank 51.
  • FIG. 4 A further arragement is illustrated in FIG. 4, where the strip 70 also travels through two tanks 71, 72 in succession, each tank being arranged structurally as the tank 52 of FIG. 3, with provision for circulating electrolyte (turbulently) along both the upper and lower faces of the horizontal strip in each case and with appropriate seals for entrance and exit of the strip.
  • Electrodes 73, 74 are respectively provided, e.g. graphite electrodes, above the strip in each tank, and are connected to the terminals of an alternating current source 75.
  • alternating current is supplied through the electrolyte in each tank to the strip, i.e. from the electrodes, so that there is no metallic contact necessary with the strip.
  • sulfuric acid electrolytes are particularly effective in the procedures of the invention and thus represent a cooperating feature of the treatment, other electrolytes appropriate for anodizing operations may be employed in some cases, e.g. acid electrolytes of generally equivalent function.
  • suitable electrolytes for the anodic treatments here described are sulfuric acid, chromic acid, diand tri-basic organic acids, or their equivalents, either separately or in suitable combination, all as will be readily understood by persons familiar with the art of anodic treatment of aluminum to produce porous-type oxide films.
  • a method of continuously anodizing aluminum sheet to provide a porous anodic coating, on one side only, of saidsheet comprising advancing the sheet through a treating zone while flowing first and second bodies of liquid in turbulent flow respectively over the opposite surfaces of said sheet, said first body of liquid being an anodizing electrolyte, and while passing electric current, at said treating zone, between the aluminum sheet and said first body of liquid at a density of at least 100 amperes per square foot of the surface of the sheet exposed to the first body, for anodizing said surface exposed to said first body to produce said anodic coat- 1ng, and while causing the sheet and the anodic coating thereon to reach a sufliciently elevated temperature during said anodizing operation by maintaining the temperatures of the bodies flowing over both said surfaces at sufliciently high values, of which the sum is greater than 100 C., for providing a one-side anodized sheet that is conditioned to be capable of receiving subsequent high temperature sealing treatment without impairment of the coating.
  • each electrolyte is a sulfuric acid solution having a concentration selected in the range of about 2% to about 40%.
  • a method of continuously anodizing one side only of an aluminum sheet to provide a porous anodic coating thereon comprising advancing the sheet in submerged contact with bodies of aqueous liquid respectively at the surfaces of the sheet, at least one of said bod'es of liquid, in contact with a first surface of the sheet, being an anodizing electrolyte, while passing electric current between the sheet and said electrolyte at a density of at least amperes per square foot of said first surface, for anodizing said first surface to produce said anodic coating, continuously advancing both of said bodies of aqueous liquid in turbulent flow over the respective surfaces of the sheet in a direction aligned with the path of travel of the sheet, said flow being maintained in turbulence substantially uniformly across the sheet, and causing the sheet and the anodic coating thereon to reach a sufliciently elevated temperature during said anodizing operation by maintaining the temperatures of said bodies flowing over the respective surfaces at sufliciently high values, of which the sum is greater than 100 C.
  • each of said liquid bodies is a sulfuric acid solution having a concentration of about 15%.
  • a method of continuously anodizing one side only of an aluminum sheet to provide a porous anodic coating thereon comprising advancing the sheet in submerged contact with bodies of electrolyte respectively at the surfaces of the sheet, each electrolyte being a sulfuric acid solution selected in a concentration range of 2% to 50%, while passing electric current between the sheet and one body of electrolyte to which a first surface of the sheet is exposed, at a density of at least 100 amperes per square foot of said first surface, for anodizing said first surface to produce said anodic coating, continuously advancing both of said bodies of electrolyte in turbulent flow over the respective surfaces of the sheet in a direction aligned with the path of travel of the sheet, said flow being maintained in turbulence substantially uniformly across the sheet, and causing the sheet and the anodic coating thereon to reach a sufficiently elevated temperature during said anodizing operation by maintaining the temperatures of said bodies flowing over the respective surfaces at sufficiently high values, of which each is at least 20 C. and of which the sum is at
  • a method of finishing an aluminum sheet which includes continuously anodizing one side only thereof, the steps of advancing the sheet through a treating zone while flowing first and second bodies of liquid in turbulent flow respectively over the opposite surfaces of said sheet, said first body of liquid being an anodizing electrolyte, and while passing electric current, at said treating zone, between the aluminum sheet and said first body of liquid for anodizing the surface of said sheet exposed to said first body, at a current density of at least 100 amperes per square foot of said last-mentioned surface, to produce an oxide film constituting a porous anodic coating thereon, and thereafter subjecting the anodized aluminum sheet to treatment in hot aqueous liquid for sealing said oxide film, said steps of flowing said bodies of liquid over the sheet in the treating zone including maintaining the temperatures of said bodies flowing over said surfaces at values of which the sum is at least 100 C., for so thermally conditioning the sheet during anodizing, as to prevent impairment of said film by said hot sealing.
  • said steps of advancing said bodies of electrolyte over the sheet while passing said current including maintaining the temperatures of said bodies in turbulent flow over said surfaces at values which are each in the range of 20 C. to C. and of which the sum is greater than 100 C., for so thermally conditioning the sheet during anodizing, as to prevent impairment of said film by said high temperature sealing.

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US342451A 1964-02-04 1964-02-04 One-side anodizing of aluminum sheet Expired - Lifetime US3359190A (en)

Priority Applications (9)

Application Number Priority Date Filing Date Title
NL129563D NL129563C (de) 1964-02-04
GB1055001D GB1055001A (de) 1964-02-04
US342451A US3359190A (en) 1964-02-04 1964-02-04 One-side anodizing of aluminum sheet
DE1965A0048228 DE1496713B1 (de) 1964-02-04 1965-01-25 Verfahren zum kontinuierlichen anodischen oxydieren von aluminiumstreifen
FR3545A FR1424643A (fr) 1964-02-04 1965-01-28 Procédé pour l'anodisation de l'aluminium
NL6501359A NL6501359A (de) 1964-02-04 1965-02-03
SE01428/65A SE326352B (de) 1964-02-04 1965-02-04
NO156638A NO115611B (de) 1964-02-04 1965-02-04
BE659263A BE659263A (de) 1964-02-04 1965-02-04

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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3459651A (en) * 1966-05-02 1969-08-05 Gen Electric Process of continuously forming bipolar electrodes by the use of electrophoresis
US3535222A (en) * 1964-02-04 1970-10-20 Aluminium Lab Ltd Apparatus for continuous electrolytic treatment
US3755116A (en) * 1971-04-17 1973-08-28 Sumitomo Light Metal Ind Process for the production of aluminum base offset printing plates
US3873318A (en) * 1972-06-08 1975-03-25 Alcan Res & Dev Production of lithographic plates
US4014758A (en) * 1974-04-23 1977-03-29 Pilot Man-Nen-Hitsu Kabushiki Kaisha Continuous electrolytical treatment of aluminum or its alloys
US4248674A (en) * 1979-09-20 1981-02-03 Leyh Henry W Anodizing method and apparatus
US4322280A (en) * 1979-12-11 1982-03-30 Siemens Aktiengesellschaft Electrolysis device for the galvanic reinforcement of tape-shaped plastic foils which are precoated to be conductive
US4470884A (en) * 1981-08-07 1984-09-11 National Ano-Wire, Inc. High speed aluminum wire anodizing machine and process
US4589959A (en) * 1983-12-27 1986-05-20 Permelec Electrode Ltd. Process for electrolytic treatment of metal by liquid power feeding
US20060201817A1 (en) * 2003-09-12 2006-09-14 Michael Guggemos Device and method for electrolytically treating electrically insulated structures
CN103255462A (zh) * 2013-04-17 2013-08-21 佛山科学技术学院 阳极氧化铝型材的环保封孔液及其应用于封孔的方法
CN111793816A (zh) * 2020-07-31 2020-10-20 常州费曼生物科技有限公司 单面阳极氧化多孔输液器滤膜连续阳极氧化设备及工艺

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5481133A (en) * 1977-12-12 1979-06-28 Fuji Photo Film Co Ltd Anodic oxidation device

Citations (5)

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US2370973A (en) * 1941-11-22 1945-03-06 William C Lang Method and apparatus for producing coated wire
GB608557A (en) * 1946-02-26 1948-09-16 John Macrae Perfect Improvements in or relating to the production of anodic films on metal surfaces
US2930739A (en) * 1956-06-28 1960-03-29 Burnham John Method and apparatus for forming valve metal foil
US2989445A (en) * 1958-01-03 1961-06-20 Lloyd Metal Mfg Company Ltd Continuous electrolytic surfacing of metal membranes
US3079308A (en) * 1958-10-07 1963-02-26 Reynolds Metals Co Process of anodizing

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AT222453B (de) * 1957-08-12 1962-07-25 Alfred James Lloyd Verfahren und Vorrichtung zur vorzugsweise kontinuierlichen einseitigen Anodisierung von Metallfolien oder- bändern

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2370973A (en) * 1941-11-22 1945-03-06 William C Lang Method and apparatus for producing coated wire
GB608557A (en) * 1946-02-26 1948-09-16 John Macrae Perfect Improvements in or relating to the production of anodic films on metal surfaces
US2930739A (en) * 1956-06-28 1960-03-29 Burnham John Method and apparatus for forming valve metal foil
US2989445A (en) * 1958-01-03 1961-06-20 Lloyd Metal Mfg Company Ltd Continuous electrolytic surfacing of metal membranes
US3079308A (en) * 1958-10-07 1963-02-26 Reynolds Metals Co Process of anodizing

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3535222A (en) * 1964-02-04 1970-10-20 Aluminium Lab Ltd Apparatus for continuous electrolytic treatment
US3459651A (en) * 1966-05-02 1969-08-05 Gen Electric Process of continuously forming bipolar electrodes by the use of electrophoresis
US3755116A (en) * 1971-04-17 1973-08-28 Sumitomo Light Metal Ind Process for the production of aluminum base offset printing plates
US3873318A (en) * 1972-06-08 1975-03-25 Alcan Res & Dev Production of lithographic plates
USRE31901E (en) * 1974-04-23 1985-05-28 Pilot Man-Nen-Hitsu Kabushiki Kaisha Continuous electrolytical treatment of aluminum or its alloys
US4014758A (en) * 1974-04-23 1977-03-29 Pilot Man-Nen-Hitsu Kabushiki Kaisha Continuous electrolytical treatment of aluminum or its alloys
US4248674A (en) * 1979-09-20 1981-02-03 Leyh Henry W Anodizing method and apparatus
US4322280A (en) * 1979-12-11 1982-03-30 Siemens Aktiengesellschaft Electrolysis device for the galvanic reinforcement of tape-shaped plastic foils which are precoated to be conductive
US4470884A (en) * 1981-08-07 1984-09-11 National Ano-Wire, Inc. High speed aluminum wire anodizing machine and process
US4589959A (en) * 1983-12-27 1986-05-20 Permelec Electrode Ltd. Process for electrolytic treatment of metal by liquid power feeding
US20060201817A1 (en) * 2003-09-12 2006-09-14 Michael Guggemos Device and method for electrolytically treating electrically insulated structures
CN103255462A (zh) * 2013-04-17 2013-08-21 佛山科学技术学院 阳极氧化铝型材的环保封孔液及其应用于封孔的方法
CN103255462B (zh) * 2013-04-17 2016-01-27 佛山科学技术学院 阳极氧化铝型材的环保封孔液及其应用于封孔的方法
CN111793816A (zh) * 2020-07-31 2020-10-20 常州费曼生物科技有限公司 单面阳极氧化多孔输液器滤膜连续阳极氧化设备及工艺
CN111793816B (zh) * 2020-07-31 2022-03-25 常州费曼生物科技有限公司 单面阳极氧化多孔输液器滤膜连续阳极氧化设备及工艺

Also Published As

Publication number Publication date
NL129563C (de)
NO115611B (de) 1968-10-28
GB1055001A (de)
NL6501359A (de) 1965-08-05
DE1496713B1 (de) 1971-06-03
SE326352B (de) 1970-07-20
BE659263A (de) 1965-08-04

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