WO2014060344A1 - Procédé de galvanisation électrolytique sans formation d'hydrogène - Google Patents

Procédé de galvanisation électrolytique sans formation d'hydrogène Download PDF

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Publication number
WO2014060344A1
WO2014060344A1 PCT/EP2013/071406 EP2013071406W WO2014060344A1 WO 2014060344 A1 WO2014060344 A1 WO 2014060344A1 EP 2013071406 W EP2013071406 W EP 2013071406W WO 2014060344 A1 WO2014060344 A1 WO 2014060344A1
Authority
WO
WIPO (PCT)
Prior art keywords
tub
galvanizing
concentration
comprised
phase
Prior art date
Application number
PCT/EP2013/071406
Other languages
English (en)
Inventor
Luca MOSCHETTANI
Original Assignee
Italnasa S.R.L.
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 Italnasa S.R.L. filed Critical Italnasa S.R.L.
Publication of WO2014060344A1 publication Critical patent/WO2014060344A1/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
    • C25D3/22—Electroplating: Baths therefor from solutions of zinc
    • 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
    • C23G—CLEANING OR DE-GREASING OF METALLIC MATERIAL BY CHEMICAL METHODS OTHER THAN ELECTROLYSIS
    • C23G1/00—Cleaning or pickling metallic material with solutions or molten salts
    • C23G1/02—Cleaning or pickling metallic material with solutions or molten salts with acid solutions
    • C23G1/08—Iron or steel
    • 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
    • C25D5/34—Pretreatment of metallic surfaces to be electroplated
    • 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
    • C25D5/34—Pretreatment of metallic surfaces to be electroplated
    • C25D5/36—Pretreatment of metallic surfaces to be electroplated of iron or steel

Definitions

  • the present patent application for industrial invention relates to an electrolytic galvanizing process without hydrogen formation.
  • galvanizing is the process used to apply a zinc coating on a metal part, generally a steel part, to protect it against galvanic corrosion.
  • the galvanizing process can be made according to different methodologies, such as:
  • Hot galvanizing generally refers to immersion in melted zinc at an average temperature of 455° C. In this phase, in addition to covering steel, zinc forms an alloy with the surface layer, giving mechanical resistance and grip to the treated material.
  • the material to be treated is suitably prepared (pre-degreased, pickled and degreased). From now onwards the process is different, since the material is immediately immersed in an electrolytic solution containing zinc salts. Finally, a current passage is created between part and solution, causing the metallic zinc to deposit on the part surface.
  • the galvanizing process of the invention is of electrolytic type and is specifically designed to avoid the spontaneous formation of hydrogen during the galvanizing process, being it a frequent, rather dangerous phenomenon that causes the weakening of galvanized parts.
  • the galvanized material is brought to a temperature of about two hundred degrees Centigrade for a minimum of two hours.
  • the ISO 9588 standard recommends to carry out said baking process before the chromatizing treatment (or passivation) in order to avoid losing its efficacy, since all passivation treatments, which are extremely important in terms of salt spray resistance (appearance of white spots), cannot withstand a thermal shock higher than 190 °C - 220 °C.
  • the standard recommends that the duration of the baking process must be at least four hours in order to harmonize the temperature of treated parts as much as possible.
  • said baking process can attenuate said hydrogen-caused weakening effect, but cannot eliminate it completely, as confirmed by the standard UNI EN ISO 4042:2003.
  • EP0545089 discloses an additive composition used in galvanic acid baths containing zinc or a mixture of zinc ions and at least one additional metal chosen between nickel and cobalt.
  • the galvanic baths also contain chloride ions or a mixture of chloride ions and sulphate.
  • EP0498436 discloses a zinc electroplating process of an aluminum strip. This process can be made continuously at high speed and high current density. According to this process, the aluminum strip undergoes anodic electrolysis before cathodic electrolysis in zinc acid.
  • the main purpose of the present invention is to devise a new electrolytic galvanizing process in which all treatment phases are free from the risk of causing spontaneous hydrogen formation, thus eliminating the need for successive baking treatments.
  • the preparation phase of a traditional electrolytic galvanizing process includes a first chemical anodic degreasing treatment, followed by a second electrolytic degreasing treatment with an alkaline liquid submitted to a voltage of 10/12 volts for approximately two minutes.
  • the two successive degreasing treatments were eliminated and replaced by other treatments because it was observed that they favored the undesired formation of hydrogen that tends to infiltrate and stagnate in the internal and surface interstices of the parts, thus causing the aforesaid weakening.
  • the material is degreased with a mechanical-chemical treatment.
  • the rotobarrel loaded with parts to be galvanized is immersed for a predefined time into a tub that contains chemical degreasing agents that are able to clean the parts without minimally impairing their mechanical resistance features.
  • Said mechanical action originates from the continuous chaotic mixing of parts inside the rotobarrel.
  • the galvanizing process of the invention is different for the implementation of the pickling phase amongst the preparation treatments before the final galvanizing phase.
  • the pickling tub used in traditional galvanizing processes has a high (higher than 30%) concentration of acid (specifically hydrochloric and sulphuric acid) at a temperature of about 35-45° C, whereas the acid concentration in the pickling tub used in the galvanizing process of the invention is reduced to approximately 10% at ambient temperature.
  • acid specifically hydrochloric and sulphuric acid
  • the galvanizing process of the invention comprises a preparation phase of the parts and a final galvanizing phase, said preparation phase being characterized in that it provides for:
  • - a mechanical-chemical degreasing treatment, during which the rotobarrel loaded with parts is immersed in a tub containing chemical degreasing substances, of known type, wherein other chemical substances, such as surface-active agents, are present in addition to 30-40% caustic soda (of the volume of liquid contained in the tub) in order to eliminate various types of oils.
  • - a pickling treatment during which the rotobarrel loaded with parts is immersed in a tub containing hydrochloric acid with approximately 10% concentration at ambient temperature for 7/12 minutes.
  • the final galvanizing phase is characterized in that:
  • - working voltage of rectifiers is not higher than 6 volts
  • the bath pH is comprised from 5.5 and 6;

Landscapes

  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Electroplating And Plating Baths Therefor (AREA)
  • Coating With Molten Metal (AREA)
  • Electroplating Methods And Accessories (AREA)

Abstract

La présente invention concerne un procédé de galvanisation électrolytique sans formation d'hydrogène, des pièces étant d'abord dégraissées à l'aide d'un traitement mécanique-chimique et soumises ensuite à un traitement de galvanisation en fonction de valeurs spécifiques des divers paramètres qui caractérisent cette phase, tels que le temps, la température et le pH du bain, la concentration de chlorures et d'acides dans ledit bain et la tension de travail de redresseurs.
PCT/EP2013/071406 2012-10-17 2013-10-14 Procédé de galvanisation électrolytique sans formation d'hydrogène WO2014060344A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
ITAN2012A000133 2012-10-17
IT000133A ITAN20120133A1 (it) 2012-10-17 2012-10-17 Processo di zincatura elettrolitica esente dalla formazione di idrogeno.

Publications (1)

Publication Number Publication Date
WO2014060344A1 true WO2014060344A1 (fr) 2014-04-24

Family

ID=47116155

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2013/071406 WO2014060344A1 (fr) 2012-10-17 2013-10-14 Procédé de galvanisation électrolytique sans formation d'hydrogène

Country Status (2)

Country Link
IT (1) ITAN20120133A1 (fr)
WO (1) WO2014060344A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114808066A (zh) * 2022-05-31 2022-07-29 无锡鹰贝电化学工程有限公司 一种磁芯管镀锌工艺

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0498436A2 (fr) 1991-02-07 1992-08-12 Sumitomo Metal Industries, Ltd. Procédé de zingage électrolytique d'une bande d'aluminium
EP0545089A2 (fr) 1991-11-05 1993-06-09 Mcgean-Rohco, Inc. Composition d'addition, bains acides d'électrodeposition de zinc et d'alliages de zinc et méthode d'électrodeposition du zinc et de ses alliages
EP1894816A2 (fr) * 2006-09-01 2008-03-05 Zeschky Galvanik GMBH & Co.KG Pivots pour suspensions de roues avant d'automobiles
DE202008014947U1 (de) * 2008-11-11 2009-03-12 Enthone Inc., West Haven Galvanisches Bad zur Abscheidung von zinkhaltigen Schichten
EP2357269A1 (fr) * 2008-11-14 2011-08-17 Yuken Industry Co., Ltd. Bain de zingage acide
FR2956668A1 (fr) * 2010-02-23 2011-08-26 Electro Rech Procede de galvanisation de pieces en fonte par electrodeposition

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0498436A2 (fr) 1991-02-07 1992-08-12 Sumitomo Metal Industries, Ltd. Procédé de zingage électrolytique d'une bande d'aluminium
EP0545089A2 (fr) 1991-11-05 1993-06-09 Mcgean-Rohco, Inc. Composition d'addition, bains acides d'électrodeposition de zinc et d'alliages de zinc et méthode d'électrodeposition du zinc et de ses alliages
EP1894816A2 (fr) * 2006-09-01 2008-03-05 Zeschky Galvanik GMBH & Co.KG Pivots pour suspensions de roues avant d'automobiles
DE202008014947U1 (de) * 2008-11-11 2009-03-12 Enthone Inc., West Haven Galvanisches Bad zur Abscheidung von zinkhaltigen Schichten
EP2357269A1 (fr) * 2008-11-14 2011-08-17 Yuken Industry Co., Ltd. Bain de zingage acide
FR2956668A1 (fr) * 2010-02-23 2011-08-26 Electro Rech Procede de galvanisation de pieces en fonte par electrodeposition

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114808066A (zh) * 2022-05-31 2022-07-29 无锡鹰贝电化学工程有限公司 一种磁芯管镀锌工艺

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ITAN20120133A1 (it) 2014-04-18

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