Zinc or zinc alloy electroplating method and system

a zinc or zinc alloy and electroplating bath technology, applied in the direction of electroplating, etc., can solve the problems of poor adhesion, inability to carry out good zinc rust-inhibiting plating, and electroplating by using an alkaline zinc nickel alloy plating bath encounters a problem, etc., to achieve economic plating, maintain the performance of the zinc or zinc alloy electroplating bath, and prolong the life

Inactive Publication Date: 2020-08-20
DISPOL CHEMICALS CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0046]The present invention makes it possible to provide an economical plating method and system capable of achieving lifetime extension while maintaining zinc or zinc alloy electroplating bath performance.

Problems solved by technology

It is to be noted that the decomposition and disappearance of these organic compounds by anodic oxidation result in dendrite deposition with poor adhesion, making it impossible to carry out good zinc rust-inhibitory plating.
However, electroplating by use of an alkaline zinc nickel alloy plating bath encounters a problem of oxidation decomposition of the amine chelating agent on the anode surface during the energizing.
Therefore, when the alkaline zinc nickel alloy plating bath comes into contact with the anode, the amine chelating agent rapidly decomposes, which rapidly decreases the plating performance.
The accumulation of decomposed products causes a number of problems such as decrease in electric current efficiency, increase in bath voltage, decrease in plating film thickness, decrease in nickel content in the plating film, reduction in current density range in which plating is possible, reduction in gloss, and increase in COD.
Therefore, it is impossible to use a plating bath for a long time, requiring the replacement of the plating bath.
However, in the case of using an acidic solution as the anolyte, an expensive corrosion-resistant member such as platinum-plated titanium has to be used as the anode.
In addition, when the separating membrane is broken, an accident may occur in which the acidic solution on the anode side and the alkaline solution on the cathode side mix to cause a sudden chemical reaction.
However, this method requires additional equipment, liquid management, and the like, making the operations complicated.
This method suppresses the oxidation decomposition of the amine chelating agent on the anode in the bath but has a problem that negative ions transfer from the plating solution to the anode electrolyte, and sodium carbonate, sodium sulfate, and sodium oxalate rapidly increase and are deposited and precipitated on the film to destroy the film.
In addition, the introduction of an anode cell is not economical because it requires a very expensive facility investment, a large installation site for an anolyte circulation tank, piping, and others, maintenance of the anode cell, regular membrane replacement, and so forth.
However, the present inventors examined it and revealed that the disclosed filtration membrane was not able to prevent the transfer of the catholyte and the anolyte and was not able to prevent the decomposition of the chelating agent on the anode.

Method used

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  • Zinc or zinc alloy electroplating method and system
  • Zinc or zinc alloy electroplating method and system
  • Zinc or zinc alloy electroplating method and system

Examples

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example 1

[0083]An anode plate (surface roughness Ra: 4 μm, 64×64×2 mm) coated with tantalum oxide in a thickness of 0.5 to 0.8 μm on Ni was used and an alkaline zinc nickel alloy plating bath shown below was used (500 mL) to carry out zinc nickel alloy plating with energizing of 500 Ah / L. The pore diameter in the coating film was 0.1 to 1 μm, and the drag-out of the plating bath was set to 2 mL / Ah. The cathode current density was 4 A / dm2, the anode current density was 9.8 A / dm2, and the plating bath temperature was 25° C. The plating bath was cooled to maintain 25° C. An iron plate was used as the cathode. Note that the iron plate of the cathode was replaced for each 16 Ah / L during the energizing. The zinc ion concentration of the plating bath was kept constant by immersion and dissolution of the metal zinc. The nickel ion concentration of the plating bath was kept constant by replenishing a nickel replenishment agent IZ-250YNi (manufactured by Dipsol). The caustic soda concentration of the ...

example 2

[0090]An anode plate (surface roughness Ra: 4 μm, 64×64×2 mm) coated with tantalum oxide in a thickness of 0.5 to 0.8 μm on Fe was used and an alkaline zinc nickel alloy plating bath shown below was used (500 mL) to carry out zinc nickel alloy plating with energizing of 500 Ah / L. The pore diameter in the coating film was 0.1 to 1 μm, and the drag-out of the plating bath was set to 2 mL / Ah. The cathode current density was 4 A / dm2, the anode current density was 9.8 A / dm2, and the plating bath temperature was 25° C. The plating bath was cooled to maintain 25° C. An iron plate was used as the cathode. Note that the iron plate of the cathode was replaced for each 16 Ah / L during the energizing. The zinc ion concentration of the plating bath was kept constant by immersion and dissolution of the metal zinc. The nickel ion concentration of the plating bath was kept constant by replenishing a nickel replenishment agent IZ-250YNi (manufactured by Dipsol). The caustic soda concentration of the ...

example 3

[0097]An anode plate (surface roughness Ra: 4 μm, 64×64×2 mm) coated with tantalum oxide in a thickness of 0.5 to 0.8 μm on Ni was used and an alkaline zinc nickel alloy plating bath shown below was used (500 mL) to carry out zinc nickel alloy plating with energizing of 500 Ah / L. The pore diameter in the coating film was 0.1 to and the drag-out of the plating bath was set to 2 mL / Ah. The cathode current density was 2 A / dm2, the anode current density was 4.9 A / dm2, and the plating bath temperature was 25° C. The plating bath was cooled to maintain 25° C. An iron plate was used as the cathode. Note that the iron plate of the cathode was replaced for each 16 Ah / L during the energizing. The zinc ion concentration of the plating bath was kept constant by immersion and dissolution of the metal zinc. The nickel ion concentration of the plating bath was kept constant by replenishing a nickel replenishment agent IZ-250YNi (manufactured by Dipsol). The caustic soda concentration of the platin...

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Abstract

The present invention provides a zinc or zinc alloy electroplating method comprising: performing energizing in an alkaline zinc or zinc alloy electroplating bath provided with a cathode and an anode, wherein the anode is an anode in which a conductive substrate is coated in a conductive state with alkali-resistant ceramics, the alkaline zinc or zinc alloy electroplating bath is an alkaline zinc plating bath containing an organic compound additive or an alkaline zinc alloy electroplating bath containing an amine chelating agent or an organic compound additive, oxidation decomposition, on a surface of the anode caused by the energizing, of the organic compound additive in the alkaline zinc plating bath or the amine chelating agent and the organic compound additive in the alkaline zinc alloy electroplating bath is suppressed as compared with a case of using as an anode the same conductive substrate uncoated with the alkali-resistant ceramics.

Description

TECHNICAL FIELD[0001]The present invention relates to a zinc or zinc alloy electroplating method and system, and in particular to an electroplating method and system for applying zinc or zinc alloy electroplating excellent in corrosion resistance to a steel member or the like by using an alkaline zinc or zinc alloy electroplating bath, in which the use of an anode in which a conductive substrate is coated in a conductive state with alkali-resistant ceramics enables long-term use of the electroplating bath while maintaining plating bath performance.BACKGROUND ART[0002]Zinc plating has been used as inexpensive rust-inhibitory plating which uses a cyan compound-containing bath and contains almost no organic compound. However, studies have been made in recent years on a zinc plating bath which uses no highly toxic cyan compound, and zinc plating baths containing organic compounds such as quaternary amine polymers have been prevailing. It is to be noted that the decomposition and disappe...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): C25D3/22
CPCC25D3/22C25D3/565C25D17/10
Inventor NIIKURA, TOSHIHIROHASHIMOTO, AKIRAINOUE, MANABU
Owner DISPOL CHEMICALS CO LTD
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