US3713902A - Process for manufacturing zinc coated steel sheet, and steel sheet obtained by this process - Google Patents

Process for manufacturing zinc coated steel sheet, and steel sheet obtained by this process Download PDF

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Publication number
US3713902A
US3713902A US00046774A US3713902DA US3713902A US 3713902 A US3713902 A US 3713902A US 00046774 A US00046774 A US 00046774A US 3713902D A US3713902D A US 3713902DA US 3713902 A US3713902 A US 3713902A
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United States
Prior art keywords
sheet
steel sheet
zinc coated
zinc
layer
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Expired - Lifetime
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US00046774A
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English (en)
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H Vrijburg
C Bijl
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KONINKLIJKE HOOGOVENS EN STAAL
KONINKLIJKE NEDERLANDSCHE HOOGOVENS EN STAALFAB NL
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KONINKLIJKE HOOGOVENS EN STAAL
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C22/00—Chemical surface treatment of metallic material by reaction of the surface with a reactive liquid, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
    • C23C22/78—Pretreatment of the material to be coated
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12535—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.] with additional, spatially distinct nonmetal component
    • Y10T428/12583—Component contains compound of adjacent metal
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/12—All metal or with adjacent metals
    • Y10T428/12493—Composite; i.e., plural, adjacent, spatially distinct metal components [e.g., layers, joint, etc.]
    • Y10T428/12771—Transition metal-base component
    • Y10T428/12785—Group IIB metal-base component
    • Y10T428/12792—Zn-base component
    • Y10T428/12799—Next to Fe-base component [e.g., galvanized]

Definitions

  • ABSTRACT Phosphated zinc coated steel sheet characterized by a phosphate layer with a mass of less than 4 g/m and with a structure which closes the zinc layer 90 percent or more, and process for improving phosphating of zinc coated steel sheet which essentially comprises passing the zinc coated sheet between elastically sur- 7 Claims, 1 Drawing Figure Int. Cl. ..C23f 7/12 Field of Search...l48/6.l5 R, 6.15 Z, 6.16, 31.5, faced rollers prior to phosphafing (IQ is 4,0 '7
  • This invention relates to a process for manufacturing an improved zinc coated steel sheet, in which such a steel sheet is submerged in a phosphate solution. This invention also relates to phosphated zinc coated steel sheet.
  • Phosphating of zinc coated steel sheet is frequently applied for electrolytically zinc coated steel strip, although it is also possible to use it for steel strip which is zinc coated by submerging in a zinc bath and for zinc coated steel sheet which is not in long strip form.
  • a layer is formed on the surface of the zinc layer, which mainly consists of Zn (PO -4I-I O This is formed in part from the bath, which among others consists of phosphoric acid and zinc phosphate, and in part from the zinc layer, which is partly dissolved in the bath.
  • the phosphating of the zinc coated steel sheet has the object to give to the sheet an electrochemical insulation, so that the adhering of lacquer thereon is improved. Moreover the corrosion resistance of the zinc layer is improved, so that the-occurrence of so-called white rust is counteracted.
  • phosphate layers have a crystalline struc ture. It is assumed that the phosphate layer may be thinner when the phosphate crystallites become smaller. About the influence of the thickness of the layer of the phosphate on the corrosion resistance little was known. It is, however, obvious to assume that a thinner phosphate layer will be better deformable than a thicker one and that thereby also the adhering of paints or lacquers on the sheet will be more favorable for a thinner phosphate layer.
  • An improved phosphated zinc coated steel sheet is according to the invention obtained by the steps to be described below, in such a way that the said disadvantages do not occur and that several advantages are obtained.
  • the invention consists in that the zinc coated steel sheet, before being submerged into the phosphate solution, is passed through at least one pair of rolls, which are pressed towards one another during this passage so as to exert on the steel sheet a force of at least 0.4 kgs per cm of roll length and preferably of about 20 kgs per cm of roll length, and that rolls are used which at least at the surface consists of rubbery material, i.e. an elastic material with rubber-like mechanical characteristics, with a hardness of 40 to shore, and preferably of 60 to 80 shore.
  • Another advantage of the invention is that less deposits are formed in the phosphate bath. This is so because the quantity of deposit is proportional to the weight of the phosphate layer. As a result thereof the composition of the phosphate bath will not change as rapidly as in known processes, which considerably promotes the economy and efficiency of the entire process.
  • a last advantage of the new process may be seen in the fact that less zinc is dissolved, so that it is possible to apply a thinner zinc layer on the steel.
  • the closed phosphate layer obtained is extremely thin, so that it is adequately deformable and thus is also better suited to be painted or lacquered as the adhering of the paint layers is better when the phosphate layer is better deformable.
  • the sheet phosphated according to this invention appears to have a deformability which is substantially the same as that of a chromated sheet.
  • a further improvement of the corrosion resistance and the paint adhering appears to be obtainable according to the invention by submerging the sheet or strip in a manner known per se, in subsequence to the submerging in the phosphate solution, into a solution on a chromate basis.
  • pacifying of a phosphate layer with the aid of for instance a chromate solution is known.
  • This may be Deoxylite 41, which is a chromate. passivating bath, containing chromium in the 6 and 3 valance states, sold by Amchem Products Inc. It has appeared, however, that the additional resistance against corrosion obtained thereby is improved considerably if this pacifying takes place on a zinc coated sheet which has been phosphated in the manner according to this invention.
  • This invention not only relates to the processes described, but also to the steel sheets obtained thereby.
  • this invention relates to a phosphated zinc coated steel sheet which is characterized by a phosphate layer with a mass ofless than 4 g per m and preferably of2 to 3 g per m and with a structure which closes the zinc layer for more than percent.
  • Nor- EXAMPLE I For comparison reasons a steel sheet was treated in a conventional manner. Thereto a steel sheet was electrolytically zinc coated in the following manner: It was started from a sheet material with a roughness of less than 30 mils.
  • This material was electrolytically degreased by treating it as a cathode in a degreasing bath of a usual commercial'quality at about 85C and with a current density of about 10 ampsldm and thereafter rinsed with water and subsequently dried.
  • a layer of zinc of about 15 g/m was deposited, which corresponds to a thickness of the zinc layer of 2 microns.
  • the sheet thus zinc coated was again rinsed in water and dried.
  • the weight of the phosphate layer formed was measured and expressed in grams /m".
  • the salt spray test according to BS 1224-1959 was made in the following way: During 3 minutes of each hour a fog of a solution in water of 3 percent NaClwas sprayed at room temperature in a closed box containing the samples. After four days the samples were examined visu ally. Thus they were judged with respect to the presenceof zinc salts (white rust! or iron oxides (red rustl).
  • the lacquer bond test according toMachu was made as follows: The samples were painted with an alkydmelamine lacquer sold in the trade'bythe Dutch firm Sikkens as baking enamel M49/l2. A lacquer layer of 25 microns was applied and thereafter it was baked at C during 30 minutes.
  • EXAMPLE II A similar steel sheet to that of Example I was zinc coated under the same circumstances. Before phosphating in a similar manner, the sheet was passed under different conditions four times between rubber rolls. In the first experiment the rolls were coated with rubber of 80 shore for the upper roll and 60 shore for the lower roll. The rolls had a diameter of 40 mm and were rotated with a peripheral speed of 500 m per hour. With roll pressures of 0.4 kg/cm and 20 kg/cm it was examined for different phosphating periods how the weight of the formed phosphate layer in glm changed.
  • the phosphate layer builds up very rapidly, but the weight thereof soon reaches a certain limit.
  • the phosphate layer builds up very slowly, but'only at very much thicker layers a deceleration in the formation thereof was found.
  • the non-pretreated sheet had a phosphate layer with a coarse structure, which layer moreover only started to close after a phosphating time of 5 seconds and was only fully closed after about seconds.
  • the rolled" sheets showed a very fine structure of the phosphate layer and this layer was already entirely continuous and closed within 2 to 3 seconds.
  • EXAMPLE IV A zinc coated sheet was passed four times between rubber rolls before being phosphated.
  • the pressure of the rolls was 20 kg/cm, the roll speed was 500 m/hour and the roll diameter was 40 mm.
  • the rolls had a shore hardness of
  • the results of the salt spray test (experiment B) and of the Machu-lacquer bond test (experiment C) were determined in a similar way as for the sheet of example I.
  • the following table gives the results:
  • An improved process for manufacturing phosphated zinc coated steel sheet which process comprises thestep of a. effecting phosphating of the zinc coated steel sheet by submerging the same in a phosphating solution,
  • the improvement comprises b. passing the zinc coated steel sheet, before subjecting it to step (a), between at least one pair of rolls with surfaces of rubbery material having a shore hardness of 40 to and c. causing the said rolls during step (b) to exert on the sheet a force of at least 0.4 Kg/cm of roll length.
  • step (a) the submergence of the rolled sheet is maintained only about 3 seconds and at a temperature of about 70C.
  • step (b) is practiced by passing the zinc coated sheet between such rolls 3 or 4 times before it is subjected to step (a).
  • claim 1 the process of claim 1, said sheet having a phosphate layer with a mass of less than 4 g/m and a structure which is over percent closed over the zinc'layer,

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  • Chemical & Material Sciences (AREA)
  • General Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Chemical Treatment Of Metals (AREA)
US00046774A 1969-06-18 1970-06-16 Process for manufacturing zinc coated steel sheet, and steel sheet obtained by this process Expired - Lifetime US3713902A (en)

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NL6909307A NL6909307A (enrdf_load_stackoverflow) 1969-06-18 1969-06-18

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US3713902A true US3713902A (en) 1973-01-30

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US (1) US3713902A (enrdf_load_stackoverflow)
DE (1) DE2029660A1 (enrdf_load_stackoverflow)
GB (1) GB1267172A (enrdf_load_stackoverflow)
NL (1) NL6909307A (enrdf_load_stackoverflow)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4629659A (en) * 1983-05-14 1986-12-16 Kawasaki Steel Corporation Corrosion resistant surface-treated steel strip and process for making
US5114799A (en) * 1990-01-30 1992-05-19 Nisshin Steel Company, Ltd. Material for roofing and facing

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2373433A (en) * 1944-10-13 1945-04-10 Parker Rust Proof Co Method of expediting chemical coatings on metal
US2795518A (en) * 1954-04-14 1957-06-11 American Chem Paint Co Process for treating steel, zinc, and aluminum to increase corrosion resistance

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2373433A (en) * 1944-10-13 1945-04-10 Parker Rust Proof Co Method of expediting chemical coatings on metal
US2795518A (en) * 1954-04-14 1957-06-11 American Chem Paint Co Process for treating steel, zinc, and aluminum to increase corrosion resistance

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
Machu, Werkstoffe und Korrosion 7(1963) pp. 370, 373. *
Spring, Metal Finishing, May 1965, p. 62. *

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4629659A (en) * 1983-05-14 1986-12-16 Kawasaki Steel Corporation Corrosion resistant surface-treated steel strip and process for making
US5114799A (en) * 1990-01-30 1992-05-19 Nisshin Steel Company, Ltd. Material for roofing and facing

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DE2029660A1 (de) 1971-01-07
GB1267172A (enrdf_load_stackoverflow) 1972-03-15
NL6909307A (enrdf_load_stackoverflow) 1970-12-22

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