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WO1991004359A1 - Ameliorations relatives au depot electrolytique de revetements en zinc ou en alliage de zinc - Google Patents

Ameliorations relatives au depot electrolytique de revetements en zinc ou en alliage de zinc Download PDF

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Publication number
WO1991004359A1
WO1991004359A1 PCT/GB1990/001433 GB9001433W WO9104359A1 WO 1991004359 A1 WO1991004359 A1 WO 1991004359A1 GB 9001433 W GB9001433 W GB 9001433W WO 9104359 A1 WO9104359 A1 WO 9104359A1
Authority
WO
WIPO (PCT)
Prior art keywords
zinc
electrolyte
ions
range
concentration
Prior art date
Application number
PCT/GB1990/001433
Other languages
English (en)
Inventor
Colin Roscoe
Original Assignee
Electricity Association Services Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Electricity Association Services Limited filed Critical Electricity Association Services Limited
Priority to DE69008537T priority Critical patent/DE69008537D1/de
Priority to EP90914540A priority patent/EP0493479B1/fr
Publication of WO1991004359A1 publication Critical patent/WO1991004359A1/fr

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D3/00—Electroplating: Baths therefor
    • C25D3/02—Electroplating: Baths therefor from solutions
    • C25D3/56—Electroplating: Baths therefor from solutions of alloys
    • C25D3/565—Electroplating: Baths therefor from solutions of alloys containing more than 50% by weight of zinc
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D21/00—Processes for servicing or operating cells for electrolytic coating
    • C25D21/12—Process control or regulation
    • C25D21/14—Controlled addition of electrolyte components

Definitions

  • the present invention relates to the electrodeposition of zinc or zinc alloy coatings.
  • non-consumable anodes lend themselves to more flexible plant design and modes of operation. More specifically, their use simplifies the task of electrodespositing alloys having a narrow range of compositions. Conventionally in the electrodeposition of zinc alloy coatings the use of a non-consumable anode is associated with oxygen evolution as the anodic reaction.
  • the present invention provides a method for the electrodeposition onto a substrate of a coating of zinc and/or a zinc alloy which method comprises immersing in an electrolyte which contains ferrous ions and zinc ions at a pH of below 1.0, a non-consumable anode which is resistant to corrosion by ferric ions and the substrate which acts as the cathode, passing an electric current therebetween, the reaction at the anode comprising the conversion of ferrous ions to ferric ions, and concurrently with or after the electrodeposition passing the electrolyte to one or more regenerating tanks comprising metallic iron and/or metallic zinc as
  • SUBSTITUTESHEET feedstock the rate of dissolution of the feedstock being dependent upon the concentration of ferric ions in solution.
  • the anode which is used in the method of the invention may be an anode of the type currently used in the chlorine industry. These generally consist of titanium having a coating of ruthenia/titania thereon. Other anodes suitable for use in the present invention are those incorporating platinum and iridium.
  • the cathodic reaction comprises the deposition of a zinc or zinc alloy coating
  • the anodic reaction comprises the conversion of ferrous ions to ferric ions.
  • the rate of production of ferric ions at the anode will be the same as the combined rate of deposition of zinc and any other metal at the cathode.
  • the electrolyte which contains ferrous ions and zinc ions has a pH of below 1.0 and preferably has a pH in the range of from 0.0 to 0.7.
  • the acidity of the electrolyte solution prevents the hydrolysis of ferric ions to form ferric hydroxide. If it is desired to electrodeposit zinc as an alloy of zinc with one or more other metals then the electrolyte must contain cations of the other metal or metals.
  • Metals which can be electrodeposited together with zinc include nickel, cobalt, chromium and iron which is, of course, already present in the electrolyte solution.
  • the anion or anions for the electrolyte solution include chloride, sulphate, tetrafluoroborate, or mixtures thereof. Chloride is particularly preferred and is the anion of choice.
  • the concentration of the ferrous ions and zinc ions in the electrolyte may vary within wide limits.
  • concentration of ferrous ion will be in the range of from 0.5 to 3.0M, more preferably in
  • SUBSTITUTESHEET the range of from 0.5 to 2.0M.
  • concentration of the zinc ions is preferably in the range of from 0.1 to 2.5M.
  • the zinc ion and ferrous ion concentrations are generally linked so that when the ferrous ion concentration lies towards the lower end of the permitted range the zinc ion concentration will tend to lie towards the lower end of its range excepting that a very high zinc level is required in the alloy.
  • Zinc rich deposits containing typically less than 10% by weight of iron may be deposited from electrolytes having a ferrous ion concentration in the range of from 0.5 to 1.5M and a zinc concentration in the range of from 0.4 to 1.5M. If higher ferrous ion concentrations are used then an increase must be made, within the limits specified above, of the zinc ion concentration.
  • the method of the invention also encompasses the possibility of electrodepositing iron rich zinc-iron coatings.
  • These iron rich coatings may be electrodeposited from electrolytes having compositions based upon the ferrous ion and zinc ion concentration ranges stipulated above. For example, at a ferrous ion concentration of 0.9M and a zinc ion concentration of 0.15M a coating containing 70% by weight zinc and 30% by weight of iron can be electrodeposited, whereas when the ferrous ion concentration is raised to 1.8M, the zinc ion concentration in the electrolyte has to be raised to 2.1M to produce the same coating. A zinc ion concentrate of 0.15M would under these circumstances yield an alloy containing from 85 to 90% of iron.
  • the temperature at which the electrodeposition of the invention is carried out is generally in the range of from ambient to 60°C but higher temperatures up to 80°C can be employed for the deposition of iron rich alloys.
  • the temperature of the electrodeposition of the invention is generally in the range of from ambient to 60°C but higher temperatures up to 80°C can be employed for the deposition of iron rich alloys.
  • SUBSTITUTE SHEET the electrolyte is generally osely conti _.ed to within ⁇ 1°C of a chosen value within the above stated range.
  • the current density is generally maintained within the range of 0.1A to 1.5Ac ⁇ rT 2 , and is preferably maintained to within ⁇ 2% of a value lying within this range.
  • the cathode onto which the zinc or zinc alloy coating is deposited may be any article which it is deposited to coat.
  • the cathode may be steel in the form of strip, sheet, wire or sections.
  • the electrodeposited coating produced accordingly to the invention may have a thickness varying within wide limits for example in the range of from 0.5 / _ to 125 ⁇ . Coatings having a thickness in the range of from 1 to 10 / i are particularly preferred for sheet material and coil . strip. Some specialised applications for steel ⁇ ._.re demand the heavy coating weights.
  • the electrodeposition according to the method of the present invention is carried out in a single cell or in a plurality of cells. The rate of flow of the electrolyte through the cell or cells is generally controlled in order to prevent the build-up of ferric ions in the cell and therefore keeping the rate of chemical milling of the deposit by the ferric ions to an acceptable level.
  • the spent electrolyte is then passed through one or more conditioning or regeneration tanks which contain metallic iron and/or metallic zinc, and optionally another metal as feedstock.
  • the feedstock may be a low grade scrap material comprising the requisite assortment of metals, e.g. iron, zinc, etc.
  • galvanised steel provides a low cost feedstock.
  • the stripped steel being sold at premium rates for re-processing via a pyrometallurgical route.
  • spent alkaline cells may also be used as a feedstock after a suitable pretreatment to remove the managanese dioxide and neutralise the alkali content.
  • the feedstock may be fed into a common tank or may be fed into separate regeneration tanks.
  • the feedstock may also contain another metal if the intention is to deposit a zinc alloy coating.
  • alloys of zinc with nickel, cobalt or chromium are desired the feedstock has to contain nickel, cobalt or chromium so as to provide the appropriate cations in solution.
  • the rate of dissolution of the feedstock is dependent upon the concentration of ferric ions in solution, the ferric ions having been generated at the anode during the electrodeposition reaction.
  • the ferric ions in solution react with the constituents of the feedstocks in a controlled way so as precisely to maintain the composition of the electrolyte. It is therefore possible to divert all or a part of the spent electrolyte to a particular tank and likewise to draw a particular predetermined volume of the feed electrolyte from a given tank, thereby maintaining the electrolyte compositions within a very close tolerance.
  • the overall concentration of the electrolyte is virtually automatically controlled by the anodic reaction. It is, however, necessary to replenish the anions in the electrolyte solution to replace those lost from the electrodeposition by drag out and by spillages.
  • SUBSTITUTE SHEET maintained at 50°C and flowed through an electrolytic cell.
  • the electrolytic cell comprises a ruthenised titania anode and a strip of steel as the cathode.
  • a coating comprising 96% by weight of zinc and 4% by weight of iron was deposited to a coating thickness of 2.5 after a period of time of 30 seconds.
  • the ferric ions generated at the anode being converted back to ferrous ions by contact with a metallic mixture or iron and zinc held in an electrolyte tank, thereby maintaining the desired electrolyte composition.
  • Example 1 The procedure of Example 1 was repeated except that the concentration of zinc ions in the electrolyte was only 10 grams per litre. A coating comprising 70% by weight of zinc and 30% by weight of iron was deposited to a thickness of 8 ⁇ in 90 seconds. The ferric ions generated at the anode being converted back to ferrous ions by contact with a metallic mixture or iron and zinc held in an electrolyte tank, thereby maintaining the desired electrolyte composition.
  • Example 2 The procedure of Example 1 was repeated except that the concentration of ferrous ions was 1.4M and the concentration of zinc ions was 45 grams per litre. A coating comprising 80% by weight of zinc and 20% by weight of iron was deposited to a thickness of 2.5/i in 30 seconds. The ferric ions generated at the anode being converted back to ferrous ions by contact with a metallic mixture or
  • Example 2 The procedure of Example 1 was repeated except that the concentration of ferrous ions was 1.4M and the concentration of zinc ions was 25 grams per litre. A coating comprising 70% by weight of zinc and 30% by weight of iron was deposited to a thickness of 2.5 ⁇ in 30 seconds. The ferric ions generated at the anode being converted back to ferrous ions by contact with a metallic mixture or iron and zinc held in an electrolyte tank, thereby maintaining the desired electrolyte composition.
  • Example 2 The procedure of Example 1 was repeated except that the concentration of ferrous ions in the electrolyte was 1.8M and the concentration of zinc ions 120 grams per litre. A coating comprising 65% by weight of zinc and 35% by weight of iron was deposited to a thickness of 8 ⁇ in 90 seconds. The ferric ions generated at the anode being converted back to ferrous ions by contact with a metallic mixture or iron and zinc held in an electrolyte tank, thereby maintaining the desired electrolyte composition.
  • Example 5 The procedure of Example 5 was repeated except that the concentration of zinc ions was adjusted to 90 grams per litre. A coating comprising 50% by weight of zinc and 50% by weight of iron was
  • SUBSTITUTESHEET deposited to a thickness of 2 ⁇ in 30 seconds.
  • the ferric ions generated at the anode being converted back to ferrous ions by contact with a metallic mixture or iron and zinc held in an electrolyte tank, thereby maintaining the desired electrolyte composition.
  • Example 2 The procedure of Example 1 was repeated except that the concentration of ferrous ions was 2.5M and the concentration of zinc ions was 90 grams per litre. A coating comprising 27% by weight of zinc and 73% by weight of iron was deposited to a thickness of 2.0 ⁇ in 30 seconds. The ferric ions generated at the anode being converted back to ferrous ions by contact with a metallic mixture or iron and zinc held in an electrolyte tank, thereby maintaining the desired electrolyte composition.
  • Example 2 The procedure of Example 1 was repeated except that the concentration of ferrous ions was 2.9M and the concentration of zinc ions was 60 grams per litre and the electrolyte temperature was raised to 75°C. A coating comprising 15% by weight of zinc and 85% by weight of iron was deposited to a thickness of 2.O in 30 seconds. The ferric ions generated at the anode being converted back to ferrous ions by contact with a metallic mixture or iron and zinc held in an electrolyte tank, thereby maintaining the desired electrolyte composition.

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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)
  • Automation & Control Theory (AREA)
  • Electroplating And Plating Baths Therefor (AREA)

Abstract

Procédé de dépôt électrolytique sur un substrat d'un revêtement de zinc et/ou d'alliage de zinc, consistant à immerger dans un électrolyte contenant des ions ferreux et des ions de zinc à un pH inférieur à 1,0 une anode non consommable résistante à la corrosion par des ions ferriques et le substrat faisant office de cathode, à faire passer un courant électrique entre ces derniers, la réaction au niveau de l'anode consistant en la transformation d'ions ferreux en ions ferriques, et simultanément avec ou après le dépôt électrolytique, à faire passer l'électrolyte dans un ou plusieurs réservoirs de régénération comprenant du fer métallique et/ou du zinc métallique utilisé comme charge d'alimentation, la vitesse de dissolution de la charge d'alimentation dépendant de la concentration d'ions ferriques en solution.
PCT/GB1990/001433 1989-09-22 1990-09-18 Ameliorations relatives au depot electrolytique de revetements en zinc ou en alliage de zinc WO1991004359A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE69008537T DE69008537D1 (de) 1989-09-22 1990-09-18 Elektroplattierung von zink- oder zinklegierungsbeschichtungen.
EP90914540A EP0493479B1 (fr) 1989-09-22 1990-09-18 Ameliorations relatives au depot electrolytique de revetements en zinc ou en alliage de zinc

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB898921439A GB8921439D0 (en) 1989-09-22 1989-09-22 Improvements in or relating to the electrodeposition of zinc or zinc alloy coatings
GB8921439.9 1989-09-22

Publications (1)

Publication Number Publication Date
WO1991004359A1 true WO1991004359A1 (fr) 1991-04-04

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1990/001433 WO1991004359A1 (fr) 1989-09-22 1990-09-18 Ameliorations relatives au depot electrolytique de revetements en zinc ou en alliage de zinc

Country Status (4)

Country Link
EP (1) EP0493479B1 (fr)
DE (1) DE69008537D1 (fr)
GB (1) GB8921439D0 (fr)
WO (1) WO1991004359A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992020839A1 (fr) * 1991-05-13 1992-11-26 Andritz-Patentverwaltungs-Gesellschaft Mbh Procede et dispositif pour appliquer un revetement electrolytique en acier, sur l'une des faces ou sur les deux faces d'un objet
WO2001068953A1 (fr) * 2000-03-17 2001-09-20 Atotech Deutschland Gmbh Procede et dispositif pour reguler la concentration d'ions metalliques dans un electrolyte, mise en oeuvre dudit procede et utilisation dudit dispositif

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4818711B1 (fr) * 1969-05-03 1973-06-07
JPS58151489A (ja) * 1982-02-27 1983-09-08 Nippon Steel Corp 鉄−亜鉛合金めつき方法
JPS627900A (ja) * 1985-07-02 1987-01-14 Sumitomo Metal Ind Ltd 亜鉛めつき浴への亜鉛イオン供給方法
JPS62243798A (ja) * 1986-04-15 1987-10-24 Kawasaki Steel Corp 電気亜鉛めつきにおけるＺｎイオンの供給方法

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4818711B1 (fr) * 1969-05-03 1973-06-07
JPS58151489A (ja) * 1982-02-27 1983-09-08 Nippon Steel Corp 鉄−亜鉛合金めつき方法
JPS627900A (ja) * 1985-07-02 1987-01-14 Sumitomo Metal Ind Ltd 亜鉛めつき浴への亜鉛イオン供給方法
JPS62243798A (ja) * 1986-04-15 1987-10-24 Kawasaki Steel Corp 電気亜鉛めつきにおけるＺｎイオンの供給方法

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Week 197324, Derwent World Patents Index; AN 1973-34674U *
PATENT ABSTRACTS OF JAPAN vol. 007, no. 273 (C - 198)<1418> 6 December 1983 (1983-12-06) *
PATENT ABSTRACTS OF JAPAN vol. 011, no. 185 (C - 428)<2632> 12 June 1987 (1987-06-12) *
PATENT ABSTRACTS OF JAPAN vol. 012, no. 122 (C - 488)<2969> 15 April 1988 (1988-04-15) *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1992020839A1 (fr) * 1991-05-13 1992-11-26 Andritz-Patentverwaltungs-Gesellschaft Mbh Procede et dispositif pour appliquer un revetement electrolytique en acier, sur l'une des faces ou sur les deux faces d'un objet
US5637205A (en) * 1991-05-13 1997-06-10 Andritz-Patentverwaltungs-Gesellschaft M.B.H. Process for the electrolytical coating of an object of steel on one or both sides
WO2001068953A1 (fr) * 2000-03-17 2001-09-20 Atotech Deutschland Gmbh Procede et dispositif pour reguler la concentration d'ions metalliques dans un electrolyte, mise en oeuvre dudit procede et utilisation dudit dispositif
US6899803B2 (en) 2000-03-17 2005-05-31 Atotech Deutschland Gmbh Method and device for the regulation of the concentration of metal ions in an electrolyte and use thereof

Also Published As

Publication number Publication date
GB8921439D0 (en) 1989-11-08
EP0493479B1 (fr) 1994-04-27
EP0493479A1 (fr) 1992-07-08
DE69008537D1 (de) 1994-06-01

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