US2812296A - Electrochemical method for coating steel surfaces and the product thereof - Google Patents

Electrochemical method for coating steel surfaces and the product thereof Download PDF

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Publication number
US2812296A
US2812296A US593217A US59321756A US2812296A US 2812296 A US2812296 A US 2812296A US 593217 A US593217 A US 593217A US 59321756 A US59321756 A US 59321756A US 2812296 A US2812296 A US 2812296A
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US
United States
Prior art keywords
solution
steel
film
coating
strip
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Expired - Lifetime
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US593217A
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English (en)
Inventor
Richard A Neish
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United States Steel Corp
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United States Steel Corp
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Filing date
Publication date
Priority to FR1080914D priority Critical patent/FR1080914A/fr
Priority claimed from GB1663753A external-priority patent/GB745676A/en
Priority to DEU2239A priority patent/DE1004012B/de
Priority to BE521089D priority patent/BE521089A/xx
Application filed by United States Steel Corp filed Critical United States Steel Corp
Priority to US593217A priority patent/US2812296A/en
Priority to DEU4079A priority patent/DE1040871B/de
Priority to GB27373/56A priority patent/GB825862A/en
Priority to FR70572D priority patent/FR70572E/fr
Priority to BE551710D priority patent/BE551710A/xx
Publication of US2812296A publication Critical patent/US2812296A/en
Application granted granted Critical
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
    • C25D11/36—Phosphatising
    • 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
    • C25D11/38—Chromatising
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D9/00—Electrolytic coating other than with metals
    • C25D9/04—Electrolytic coating other than with metals with inorganic materials
    • C25D9/08—Electrolytic coating other than with metals with inorganic materials by cathodic processes
    • C25D9/10—Electrolytic coating other than with metals with inorganic materials by cathodic processes on iron or steel

Definitions

  • This invention relates to a process for treating the sur faces of steel products such as ordinary uncoated sheet steel (black plate) to increase its corrosion resistance and the adherence of the lacquer coating usually applied to can stock, so it may be used safely and satisfactorily as a substitute for tin-plate in the manufacture of cans intended for packing certain commodities which have heretofore required tin cans.
  • Containers made from lacquered black plate have been used for packing dryproducts and non-corrosive products 'such' as lubricating oil,
  • lacquered black plate containers for the packaging of foods and, certain other 'wet products, however, has not been feasible.
  • the ad- :herence of .the lacquer to the steel is often insufiicient to known commercial phosphating process includes precleaning, rinsing, phosphating, rinsing,-dichromate rinsing, and drying.
  • The.solutions are carefully balanced mixtures that must be. properly controlled, and several sets of variable-speed scrubbing rolls are used as accessories.
  • Figure 1 is a diagrammatic showing of the apparatus .for performing my method.
  • the tank is fitted with guide rollers 13 and contains a bath of treating solution 15, the rollers being disposed so as to cause the strip to be progressively immersed in the bath during its travel into and out of the tank.
  • Squeegee or wringer rolls 16 at the exit end of the tank wipe excess solution from the strip leaving it uniformly covered with a thin liquid film.
  • Bath 15 is an acid aqueous solution containing phosphate ions and the ions of chromium compounds in which the chromium is hexavalent, and has a pH value from about 1 to 2.
  • the phosphate ions may be supplied by I phosphoric acid or by a soluble phosphate such as sodium,
  • the solution may conveniently be prepared by adding to .water from 1 to 6% sodium dichromate by weight and from .75 to 6% by volume of ortho-phosphoric acid This gives a solution containing from 1.0 to 8.4% of the phosphate radical and from .3 to 2.1% chromium, both by weight.
  • a preferred composition is:
  • This solution has a pH value of about 1.
  • the solution may also be prepared by using chemically equivalent amounts of other salts or acids as stated above.
  • I may find it desirable to add other salts to the solution to obtain further improvement in the character of the coatings.
  • I may add from 1 to 4% of sodium nitrate (preferably 1%), or 0.1 to 0.4% of potassium permanganate (preferably 0.2%). ;These help to produce a uniform coating of the desired -type, and "tend to improve the properties of the film.
  • the nitrate is the more stable under commercial operating conditions. If NaNOa is used, the total NaNOa including that from the nitric acid for control of pH, should not exceed the equivalent of 4% NaNOs.
  • the bath 15 is maintained at a temperature between 100 and 160 F. and :preferablybetween 120 and 140 F.,'by any convenient means such as steam coils immersed therein.
  • the film applied to the strip, after drying, is heavier but is chalky providing neither adequate corrosion resistance nor lacquer adherence.
  • the film is invisible and the lacquer adherence is impaired.
  • Films produced at a bath temperature of from about 120 to 130 F. are the most effective in improving the corrosion resistance and lacquer adherence and are smoky gray in appearance.
  • the cathodic electrolytic action to which the strip is subjected reduces the metallic oxide existing on the sur face of the steel and forms a thin boundary film of a microcrystalline phase of unknown composition. It is believed that this microcrystalline phase then partially reacts with the solution film that is dragged out on the strip; the remainder of the solution film tending to seal the coating when it is dried.
  • the exact nature of the reaction or the character of the coating produced on drying the residual film of the solution is not known precisely but the effect thereof in improving corrosion resistance and lacquer adherence is readily determinable @by simple tests.
  • a satisfactory protective film cannot be applied without the electrolytic action.
  • the resulting film is spotty and non-uniform giving incomplete coverage and has a tendency to smear in a steamy atmosphere, and the adherence of lacquer to this coating is not satisfactory.
  • the solution can be varied appreciably without affecting the fundamentals of the process, provided that both phosphate and hexavalent chromium are present. Chromic acid or dichromate alone does not produce the desired film. Acidic phosphate solutions without 'hexavalent chromium will produce films, but'these films are definitely inferior.
  • the solutions contain appreciable quantities of zinc .or manganese phosphates. .Such additions are said to be essential in order toprevent the lattice structure of the coating from changing when exposed to corrosive conditions. My coatings have suitable corrosion resistance, even though zinc and manganese phosphates are absent.
  • the squeegee rollers :16 are preferably provided with means such as screws for adjusting the pressure exerted thereby and thus controlling the amount of the liquid film left on the strip to dry.
  • This residual film should be the minimum which, when dried, will be suflicient to give the smoky gray underlayer the maximum corrosion resistance and lacquer adherence. I .find .that a dried film weighing from 6 to 30 milligrams p. s. f. of surface is most effective.
  • the film may be dried by natural evaporation if time and space limitations permit. I prefer, however, to dry the film by passing the strip through a hot-air drier 21 having an air inlet',22 and an outlet 23, or equivalent drying means.
  • the drying is facilitated by the fact that the strip, on emerging from the bath, is at the temperature of the latter and tends, therefore, to lose moisture rapidly to the surroundingair.
  • a drive bridle 24 which pulls the strip through the processing line.
  • the drive bridle delivers the strip to aflying shear 25 which cuts itinto sheets. The severed sheetsfall onto a piler26.
  • the films applied by my invention when 'dry, are very thin and tightly adherent and have a grayish coloration. They are visible on the metal surface as the strip leaves the electrolytic bath, are already an integral part of the surface and are not removed or destroyed by normal handling even before they are dry. They thus differ from anodic or immersion films produced by baths similar to the described bath, which are like paint films and are very easily damaged while they are still wet. These immersion films consist almost totally of semi-soluble gelatinous compounds.
  • Coatings made according to the described process, with or without either of the above addition agents in the phosphate-chromate solution, are suitable for lacquering, enameling, or painting as shown in Figure 2.
  • the coatings can be further improved, however, by a secondary treatment with a suitable solution.
  • Example 1 Steel is cathodically treatedaccording to the following:
  • Example 2 Steel is cathodically treated according to the following:
  • Filmed steel strip produced according to the above method has been tested in many different ways.
  • the resistance of individual sheets to atmospheric humidity is not equal to that of tin plate, but when the treated steel is piled and wrapped in the customary fashion, its storage life is quite suitable for the purpose.
  • this treated steel has proved resistant in steam tests, in water-immersion tests, and in salt-spray tests.
  • the resistance shown in these latter tests is greatly extended by lacquering.
  • Cans made from treated and lacquered strip have been subjected to food-pack tests, and the results have been satisfactory. It has been found that treated and lacquered strip may be drawn or formed, within the limits of the distensibility of the lacquer being employed, without flaking or peeling of the lacquer.
  • lacquer adherence has also been tested by forming and doubleseaming can ends, and by the use of cup machines and bend tests.
  • a tinless container may be formed from lacquered steel strip that has been treated according to the described process.
  • such tinless containers may be used for packing or canning a variety of products which cannot be packed satisfactorily in untreated lacquered steel.
  • My improved filming process is particularly intended for the rapid, continuous treatment of cold-reduced steel strip in coils, but it is just as suitable for the treatment of sheet, pipe or formed products.
  • the filming process can beoperated at a rate of speed and with a degree of simplicity and economy previously unknown, and it is thus a marked improvement over any existing method, from the standpoint of production rate or throughput.
  • the films produced by my method may be considered as extremely thin barrier films which retard the passage of moisture, yet are ideally suited as a base for lacquers, etc.
  • the underfilm usually weighs less than .12 milligrams p. s. f. of surface area, andthe total film weight is usually less than 50 milligrams p. s. f.
  • the film made by the disclosed process is thus thinner'than the usual phosphate films.
  • the thinness of the coating is beneficial because thin films are usually more ductile for drawing and forming operations and usuallycontain less semi-soluble components. When the coating process is performed as explained herein and the squeegee rolls are properly adjusted, it is practically impossible to obtain films that are too heavy.
  • the product of the method described is resistant to corrosion when tested in water, steam and salt spray, and this resistance is greatly increased by a coating of lacquer such as that ordinarily applied to tin plate to be used as can stock, as shown in Figure 2.
  • lacquer such as that ordinarily applied to tin plate to be used as can stock, as shown in Figure 2.
  • Such coating is thus much less likely to fail through underfilm corrosion than a similar coating applied to untreated steel sheets.
  • the lacquer adherence is also materially improved by the treatment. Flaking and peeling of the lacquer coating does not occur on normal drawing or forming of the sheets.
  • the product is thus adapted for use as a substitute for tin plate for packing many products for which untreated lacquered sheets are unsuitable.
  • the surface film formed by this process also takes and holds paint well.
  • the method described is characterized by numerous advantages. It is simple, rapid and easy to control. Strip-processing speeds of several hundred feet per minute are easily obtainable. Scrubbers, cleaning solutions and rinses to remove cleaning solutions are not normally required as a pretreatment to obtain satisfactory coatings. No pretreatment nor after-treatment such as cleaning or rinsing is required although a final rinse is desirable.

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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)
  • Chemical Treatment Of Metals (AREA)
  • Preventing Corrosion Or Incrustation Of Metals (AREA)
  • Electroplating Methods And Accessories (AREA)
US593217A 1953-06-16 1956-06-22 Electrochemical method for coating steel surfaces and the product thereof Expired - Lifetime US2812296A (en)

Priority Applications (8)

Application Number Priority Date Filing Date Title
FR1080914D FR1080914A (fr) 1953-06-16 Procédé électrochimique de revêtement des surfaces en acier, produits destinés à sa mise en oeuvre et produits en résultant
DEU2239A DE1004012B (de) 1953-06-16 1953-06-22 Verfahren zum kontinuierlichen elektrolytischen Phosphatieren von Stahlerzeugnissen
BE521089D BE521089A (xx) 1953-06-16 1953-06-30
US593217A US2812296A (en) 1953-06-16 1956-06-22 Electrochemical method for coating steel surfaces and the product thereof
DEU4079A DE1040871B (de) 1953-06-16 1956-08-20 Verfahren zum kontinuierlichen elektrolytischen Phosphatieren von Stahlerzeugnissen
GB27373/56A GB825862A (en) 1953-06-16 1956-09-06 Electrochemical method for coating steel surfaces and the product thereof
FR70572D FR70572E (fr) 1953-06-16 1956-10-08 Procédé électrochimique de revêtement des surfaces en acier, produits destinés à sa mise en oeuvre et produits en résultant
BE551710D BE551710A (xx) 1953-06-16 1956-10-11

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB1663753A GB745676A (en) 1953-06-16 1953-06-16 Electrochemical method for coating steel surfaces and the product thereof
US593217A US2812296A (en) 1953-06-16 1956-06-22 Electrochemical method for coating steel surfaces and the product thereof

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US2812296A true US2812296A (en) 1957-11-05

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US593217A Expired - Lifetime US2812296A (en) 1953-06-16 1956-06-22 Electrochemical method for coating steel surfaces and the product thereof

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US (1) US2812296A (xx)
BE (2) BE521089A (xx)
DE (2) DE1004012B (xx)
FR (2) FR70572E (xx)
GB (1) GB825862A (xx)

Cited By (19)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2920019A (en) * 1957-05-17 1960-01-05 Nat Steel Corp Electrolytic treatment of black plate and product
US2974091A (en) * 1958-12-11 1961-03-07 United States Steel Corp Method of reducing eye holing in lacquered tin-plate
US3032487A (en) * 1958-05-30 1962-05-01 Yawata Iron & Steel Co Electrolytic treatment of ferrous metal surfaces
US3113845A (en) * 1960-03-29 1963-12-10 Fuji Iron & Steel Co Ltd Chromium-plated steel
US3118824A (en) * 1958-05-30 1964-01-21 Yawata Iron & Steel Co Electrolytic treatment of metal surfaces
US3160532A (en) * 1962-06-13 1964-12-08 United States Steel Corp Method of forming a protective coating
US3175964A (en) * 1960-01-23 1965-03-30 Yawata Iron & Steel Co Surface treatment of metal article by water-soluble (film-forming) material
US3257295A (en) * 1962-01-20 1966-06-21 Yawata Iron & Steel Co Method of chemically treating metals
US3278401A (en) * 1966-01-12 1966-10-11 Nat Steel Corp Method of treating tin-containing surfaces
US3288691A (en) * 1962-06-13 1966-11-29 Yawata Iron & Steel Co Method of electrolytically chemically treating metals
US3479260A (en) * 1966-03-07 1969-11-18 Bethlehem Steel Corp Treatment for ferrous surfaces
FR2004968A1 (xx) * 1968-03-28 1969-12-05 Yawata Iron & Steel Co
US3532611A (en) * 1965-05-25 1970-10-06 Nippon Kokan Kk Process for the manufacture of surface-treated metallic sheets or the like,with superior coating and anti-corrosive performance
US3865701A (en) * 1973-03-06 1975-02-11 American Chem & Refining Co Method for continuous high speed electroplating of strip, wire and the like
US4432845A (en) * 1982-07-20 1984-02-21 Kawasaki Steel Corporation Method of producing tin-free steel sheets having improved resistance to retorting treatment
US4448475A (en) * 1981-07-07 1984-05-15 David Reznick Method and apparatus for treatment of tinned metal surfaces and treated tinned metal surface
FR2552451A1 (fr) * 1983-09-28 1985-03-29 Centre Rech Fer Blanc Procede de chromage electrolytique
EP0987350A2 (de) * 1998-08-06 2000-03-22 VOEST-ALPINE AUSTRIA DRAHT GmbH Verfahren und Vorrichtung zum Aufbringen eines Phosphatüberzuges auf Werkstücke
US20080207477A1 (en) * 2006-09-21 2008-08-28 Chunwoo Tech Co., Ltd. Gel containing phosphate salts for passivation

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5610996B2 (xx) * 1974-01-14 1981-03-11

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1007069A (en) * 1910-11-25 1911-10-31 Thomas Watts Coslett Treatment of iron or steel to prevent the oxidation or rusting thereof.
US2132439A (en) * 1933-12-11 1938-10-11 American Chem Paint Co Method of producing phosphate coated ferrous articles
US2303242A (en) * 1938-11-19 1942-11-24 Parker Rust Proof Co Metal coating
US2590927A (en) * 1948-07-17 1952-04-01 Westinghouse Electric Corp Electrolytic method of removing burrs
US2606866A (en) * 1948-10-27 1952-08-12 United States Steel Corp Method of treating tin plate
US2769774A (en) * 1952-08-05 1956-11-06 Republic Steel Corp Electrodeposition method

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1007069A (en) * 1910-11-25 1911-10-31 Thomas Watts Coslett Treatment of iron or steel to prevent the oxidation or rusting thereof.
US2132439A (en) * 1933-12-11 1938-10-11 American Chem Paint Co Method of producing phosphate coated ferrous articles
US2303242A (en) * 1938-11-19 1942-11-24 Parker Rust Proof Co Metal coating
US2590927A (en) * 1948-07-17 1952-04-01 Westinghouse Electric Corp Electrolytic method of removing burrs
US2606866A (en) * 1948-10-27 1952-08-12 United States Steel Corp Method of treating tin plate
US2769774A (en) * 1952-08-05 1956-11-06 Republic Steel Corp Electrodeposition method

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2920019A (en) * 1957-05-17 1960-01-05 Nat Steel Corp Electrolytic treatment of black plate and product
US3032487A (en) * 1958-05-30 1962-05-01 Yawata Iron & Steel Co Electrolytic treatment of ferrous metal surfaces
US3118824A (en) * 1958-05-30 1964-01-21 Yawata Iron & Steel Co Electrolytic treatment of metal surfaces
US2974091A (en) * 1958-12-11 1961-03-07 United States Steel Corp Method of reducing eye holing in lacquered tin-plate
US3175964A (en) * 1960-01-23 1965-03-30 Yawata Iron & Steel Co Surface treatment of metal article by water-soluble (film-forming) material
US3113845A (en) * 1960-03-29 1963-12-10 Fuji Iron & Steel Co Ltd Chromium-plated steel
US3257295A (en) * 1962-01-20 1966-06-21 Yawata Iron & Steel Co Method of chemically treating metals
US3160532A (en) * 1962-06-13 1964-12-08 United States Steel Corp Method of forming a protective coating
US3288691A (en) * 1962-06-13 1966-11-29 Yawata Iron & Steel Co Method of electrolytically chemically treating metals
US3532611A (en) * 1965-05-25 1970-10-06 Nippon Kokan Kk Process for the manufacture of surface-treated metallic sheets or the like,with superior coating and anti-corrosive performance
US3278401A (en) * 1966-01-12 1966-10-11 Nat Steel Corp Method of treating tin-containing surfaces
US3479260A (en) * 1966-03-07 1969-11-18 Bethlehem Steel Corp Treatment for ferrous surfaces
FR2004968A1 (xx) * 1968-03-28 1969-12-05 Yawata Iron & Steel Co
US3865701A (en) * 1973-03-06 1975-02-11 American Chem & Refining Co Method for continuous high speed electroplating of strip, wire and the like
US4448475A (en) * 1981-07-07 1984-05-15 David Reznick Method and apparatus for treatment of tinned metal surfaces and treated tinned metal surface
US4432845A (en) * 1982-07-20 1984-02-21 Kawasaki Steel Corporation Method of producing tin-free steel sheets having improved resistance to retorting treatment
FR2552451A1 (fr) * 1983-09-28 1985-03-29 Centre Rech Fer Blanc Procede de chromage electrolytique
EP0987350A2 (de) * 1998-08-06 2000-03-22 VOEST-ALPINE AUSTRIA DRAHT GmbH Verfahren und Vorrichtung zum Aufbringen eines Phosphatüberzuges auf Werkstücke
EP0987350A3 (de) * 1998-08-06 2004-03-24 VOEST-ALPINE AUSTRIA DRAHT GmbH Verfahren und Vorrichtung zum Aufbringen eines Phosphatüberzuges auf Werkstücke
US20080207477A1 (en) * 2006-09-21 2008-08-28 Chunwoo Tech Co., Ltd. Gel containing phosphate salts for passivation
US7473308B2 (en) * 2006-09-21 2009-01-06 Chunwoo Tech Co., Ltd. Gel containing phosphate salts for passivation

Also Published As

Publication number Publication date
DE1040871B (de) 1958-10-09
FR1080914A (fr) 1954-12-14
DE1004012B (de) 1957-03-07
FR70572E (fr) 1959-05-29
BE551710A (xx) 1959-12-31
BE521089A (xx) 1955-08-05
GB825862A (en) 1959-12-23

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