Classifications

• • C—CHEMISTRY; METALLURGY
  • C21—METALLURGY OF IRON
  • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
  • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
  • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/10—Electroplating with more than one layer of the same or of different metals
  • C25D5/12—Electroplating with more than one layer of the same or of different metals at least one layer being of nickel or chromium
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D5/00—Electroplating characterised by the process; Pretreatment or after-treatment of workpieces
  • C25D5/48—After-treatment of electroplated surfaces
  • C25D5/50—After-treatment of electroplated surfaces by heat-treatment
• • 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
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S428/00—Stock material or miscellaneous articles
  • Y10S428/922—Static electricity metal bleed-off metallic stock
  • Y10S428/9335—Product by special process
  • Y10S428/941—Solid state alloying, e.g. diffusion, to disappearance of an original layer
• • 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
  • Y10T428/12458—All metal or with adjacent metals having composition, density, or hardness gradient
• • 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
  • Y10T428/12861—Group VIII or IB metal-base component
  • Y10T428/12937—Co- or Ni-base component next to Fe-base component

Definitions

• the invention relates to a cold strip with an electrolytically applied nickel coating.
• Cold strips of this type are used in a wide variety of fields of application where modern manufacturing processes place high demands on the material in terms of mechanical properties, surface, processability and the like, which can only be met by cold-rolled products.
• Cold strip according to DIN 1624 has smooth, dense and glossy or evenly slightly roughened surfaces after cold forming by means of the correspondingly prepared rollers.
• Cold rolled strip is free of pores and cracks in the surface types RP and RPG, so that it can be surface-finished, in particular nickel-plated, without any problems.
• a deep-drawn cold strip with an electrolytically applied nickel coating is therefore known.
• thinner galvanic coatings are generally used in the field of coil plating than is usual for piece plating. It can be achieved through suitable measures, such as shielding the anode, flooding, inserting perforated plates in front of the anodes bar that the deposition takes place in a uniform layer thickness and layer thickness differences are reduced to a minimum.
• suitable measures such as shielding the anode, flooding, inserting perforated plates in front of the anodes bar that the deposition takes place in a uniform layer thickness and layer thickness differences are reduced to a minimum.
• the thinner layers have a lower corrosion resistance than thicker galvanic layers.
• the cold-rolled strip or cold-rolled and galvanized strips has a "tendency to stick" when annealed in the closed coil. Such glue points are preferably created during the cold rolling of low-carbon cold strip, the surface of which has a minimal micro-roughness.
• the object of the invention is to develop a galvanized cold strip and a method for its production which avoid none of the disadvantages mentioned above Tends to stick, is easy to form, has high diffusion depths in the coating and has favorable corrosion behavior, its electrochemical behavior is improved and it can be produced economically.
• the object is achieved in that the nickel layer has a thickness of 1 to 6 microns and carries an electrolytically applied cobalt layer of a thickness of 0.01 to 1.0 microns, the cold strip after coating with a temperature between 580 ° C. and 710 ° C is heat treated.
• Such a coated and heat-treated cold strip surprisingly no longer tends to stick and shows a significantly more favorable corrosion behavior than the only nickel-coated strips which have the same total layer thickness.
• the electrochemical behavior of the cold strip according to the invention has values which are considerably more favorable than the only nickel-plated strips.
• Nickel coating, cobalt coating and heat treatment complement each other in a combinatorial manner to achieve an overall effect that goes beyond the sum effect, since a composite material is created which can be economically achieved with high-quality properties.
• Thermal treatment results in a significantly higher diffusion rate, which means that the quality of the formability of the composite system is improved and the penetration of the coating metals into the base material by diffusion shows a depth that is several times the coating thickness (including the nickel layer).
• the extremely thin cobalt coating a high technical and economic overall success is achieved.
• DE-OS 1 421 999 describes the cobalt coating of magnetic tapes which are made of plastic.
• DE-OS 2 048 209 requests patent protection for the production of shiny co-layers with organic additives, preferably in low current density ranges ( ⁇ 0.5 A / dm2).
• DE-OS 2 060 120 describes the co-deposition from iodide-containing electrolytes.
• DE-OS 2 134 457 mentions four additives which enable co-deposition even in the presence of Zn impurities.
• DE-OS 2 417 952 describes co-deposition (mainly co-alloys) with additions of mannitol, sorbitol etc.
• DE-PS 25 22 130 patented the deposition of satin matt Ni-Co alloys with the help of polysiloxane-polyoxyalkylene block polymers.
• DE-OS 2 642 666 describes the high-gloss Co and Ni-Co alloy deposition in order to save Ni.
• DE-OS 2 718 285 has similar objectives as DE-OS 2 642 666.
• DE-OS 3 112 919 describes the use of Co, Co alloy layers for better adhesion of the subsequent aluminum deposition.
• the base material is a low-carbon steel strip, which is nickel layer of 1.5 to 5 ⁇ m in thickness and a cobalt layer of 0.1 to 0.5 ⁇ m in thickness, the final heat treatment being carried out at a temperature between 600 ° C and 710 ° C depending on the steel grade.
• the thickness of the applied nickel layer is preferably 2 ⁇ m and the thickness of the applied cobalt layer is 0.1 ⁇ m.
• the base material of the cold strip is expediently characterized by a ferritic structure with embedded cementite with average grain sizes between 17.0 and 12.0 ⁇ m, the steel being 0.001 to 0.70% C, 0.170 to 0.350% Mn, 0.005 to 0.020% P, 0.005 to 0.020% S, 0.030 to 0.060% Al, 0.0015 to 0.0070% N, 0.003 to 0.006% B or instead of boron or additionally 0.005 to 0.15% Ti, balance iron with the usual impurities. (All data in% by weight).
• the base metal preferably has a steel analysis C 0.030 - 0.060% Mn 0.200 - 0.250% P 0.005 - 0.020% S 0.005 - 0.015% Al 0.030 - 0.060% N 0.0015 - 0.0070% Ti 0.005 - 0.015%, Remainder iron with the usual accompanying elements on. After deep drawing, smooth surfaces are achieved due to the very fine grain diameter.
• the composition of the steel is particularly important in order to achieve the globular shape of the grain and the grain size specified above over the entire ring length in the cold strip, even in the start and end areas.
• the process according to the invention for producing the cold strip described above is characterized in that a hot strip with a thickness of 1.8 to 2.8 mm is used as the starting material is used, the hot strip is cold rolled with or without intermediate annealing with such coordinated rolling degrees that a relative tip height of maximum 3% with a final thickness after cold rolling between 0.10 and 0.70 mm is reached, that the cold strip is then electrolytically in the alkaline degreasing bath at a temperature of 50 to 70 ° C, a current density of 5 to 60 A / dm2, degreased for 5 to 30 seconds with or without polarity reversal, that after a rinsing process in 50 to 20% by weight sulfuric acid 3 to 8 seconds long is picked up, then electrolytically nickel-plated at a temperature of 50 to 80 ° C, at a current density of 5 to 70 A / dm2 and at a pH value of 3.5 to 3.8, that after a rinsing process thereupon electrolytically a co
• the cold strip obtained in this way has no tendency to stick, is distinguished by a current flow which is perceptible by chronoamperometric measurements and is of a considerably higher magnitude than is known, and is extremely economical due to the thin coating with expensive cobalt.
• nickel and cobalt penetrate deeply into the base material through diffusion.
• the following electrolyte compositions can advantageously be used for the electrolytic deposition of nickel and cobalt: Nickel deposition Electrolyte composition NiSO4 ⁇ 6H2O 150-300 g / l Cl (as NiCl2 ⁇ 6H2O) 15-30 g / l Boric acid 40-42 g / l Cobalt deposition Electrolyte composition CoSO4.7H2O 300-350 g / l CoCl2 ⁇ 6H2O 40 - 60 g / l NaCl 15-25 g / l Boric acid 40-42 g / l.
• Composition A Composition C C. 0.020 - 0.070 % By weight C. 0.020 % By weight Mn 0.170 - 0.350 % By weight Mn 0.170 % By weight P 0.005 - 0.020 % By weight P 0.005 % By weight S 0.005 - 0.020 % By weight S 0.005 % By weight Al 0.030 - 0.060 % By weight Al 0.030 % By weight B 0.003 - 0.006 % By weight N ⁇ 0.0030 % By weight N ⁇ 0.0070 % By weight Composition B Composition D C. 0.030 - 0.060 % By weight C.
• Texture Ferritic structure with embedded cementite.
• the grain size is: 17.0 - 12.0 ⁇ m (expressed as the mean grain size), in the present case as globular grains, in order to achieve smooth surfaces after deep-drawing due to the very fine grain diameter.
• composition of the steel is of crucial importance in order to achieve this grain shape and grain size over the entire length of the ring, also in the start and end areas.
• the production of the finished steel strips according to the invention is based on 1.8-2.8 mm thick hot strips.
• the hot strip is cold rolled with or without intermediate annealing, with coordinated rolling degrees, to a relative tip height of max. To reach 3%.
• the final thickness after cold rolling is 0.10 - 0.70 mm.
• the refined material is annealed with a defined protective gas (with up to 100% H2) in order to achieve a stain-free surface.
• the temperature is 580 - 710 ° C depending on the steel type and applied galvanic layer thickness.
• the measurement is carried out after preactivation, which removes the natural oxide layer from the surface immediately before the chronoamperometric measurement.
• the pre-activation voltage applied was approximately -550 mV.
• the current transfer for the working electrodes constructed according to the invention was 80-80 mA. Due to the rapid formation of oxide, the current decreased very quickly and tends to asymtotically after 3 minutes to 0 mA. With the only nickel-plated working electrodes, the near O value (current) was only reached after 15-20 minutes.
• the electrode potential of the cold strip produced in accordance with the invention in alkaline electrolyte remains constant at least twice as long as the electrode consisting only of nickel-plated cold strip.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Thermal Sciences (AREA)
• Physics & Mathematics (AREA)
• Crystallography & Structural Chemistry (AREA)
• Mechanical Engineering (AREA)
• Electroplating Methods And Accessories (AREA)
• Heat Treatment Of Sheet Steel (AREA)
• Non-Insulated Conductors (AREA)
• Manufacturing Of Steel Electrode Plates (AREA)
• Solid-Phase Diffusion Into Metallic Material Surfaces (AREA)
• Electroplating And Plating Baths Therefor (AREA)

Priority Applications (1)

Applications Claiming Priority (2)

Publications (2)

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ID=6333418

Family Applications (1)

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Cited By (3)

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Citations (3)

Family Cites Families (17)

• 1987
  • 1987-08-10 DE DE19873726518 patent/DE3726518A1/de active Granted
• 1988
  • 1988-05-12 US US07/193,366 patent/US4910096A/en not_active Expired - Lifetime
  • 1988-06-28 EP EP88110266A patent/EP0303035B1/fr not_active Expired - Lifetime
  • 1988-06-28 DE DE8888110266T patent/DE3864629D1/de not_active Expired - Lifetime
  • 1988-06-28 ES ES198888110266T patent/ES2026227T3/es not_active Expired - Lifetime
  • 1988-06-28 AT AT88110266T patent/ATE66865T1/de not_active IP Right Cessation
  • 1988-07-29 JP JP63188550A patent/JPH01111895A/ja active Granted
  • 1988-08-05 MX MX012576A patent/MX169599B/es unknown
  • 1988-08-08 DD DD88318779A patent/DD272880A5/de unknown
  • 1988-08-09 BR BR8803944A patent/BR8803944A/pt not_active Application Discontinuation
  • 1988-08-09 CA CA000574171A patent/CA1322345C/fr not_active Expired - Fee Related
  • 1988-08-10 KR KR1019880010238A patent/KR960004786B1/ko not_active IP Right Cessation
• 1991
  • 1991-10-03 GR GR91401482T patent/GR3002845T3/el unknown

Patent Citations (3)

Non-Patent Citations (2)

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