Zinc alloy electroplating baths and processes

Abstract

The present invention relates to the electrodeposition of zinc nickel alloy on a variety of electrically conducting substrates in a medium which seeks to provide improved deposit distribution and operable current density range. This is achieved through a bath comprising zinc ions, nickel metal ions, and a suitable combination of one or more urea based polymers and non-polymeric complexing agents capable of holding nickel metal ions in alkaline solution and an electrolytic process whereby the bath is used to electrodeposit zinc nickel alloy on electrically conducting substrates.

Description

technical field

[0001] The present invention relates generally to improved methods of electrodepositing zinc-nickel alloys from aqueous alkaline plating baths, and novel additives for such electrodeposition methods. Background technique

[0002] Electrodeposition of zinc and zinc alloys based on alkaline plating baths has been known for many years. However, commercially acceptable deposits cannot be produced from pure sodium zincate electrolytes because such deposits are powdery and dendritic. Accordingly, various additives have been proposed to improve deposition, such as cyanide, which has significant environmental concerns, and polymers of amines and epichlorohydrin as grain refining additives. These polymers are limited to use in baths with relatively low zinc concentrations, since at higher metal concentrations uncontrolled deposition of zinc cannot be avoided. Also, electroplating processes using these additives tend to have poor cathode efficiency, narrow bright ran...

Examples

Embodiment 1

[0030] Prepare a kind of aqueous electrolytic bath that is suitable for plating zinc-nickel alloy, it contains the sodium hydroxide of 90g / L, the zinc ion of 8g / L, the nickel ion of 4g / L, the triethanolamine of 68g / L, the triethanolamine of 30g / L N,N,N',N'-tetrahydroxyisopropylethylenediamine, 12.5g / L of sodium silicate and 400mg / L of N,N'-bis[3-(dimethylamino)propyl] Polymer of urea and 1,1'-oxybis[2-chloroethane]. A bright steel Hull cell plate was plated at a current of 1 A in a Hull cell using a nickel anode for 20 minutes at a temperature of 30°C. The appearance of the plated plate is uniform and bright, with no visible defects. The deposit thicknesses and nickel alloy contents listed in Table 1 below were measured using a Fischerscope X-ray system XDL-B under conditions of current densities of 4A, 2A, and 0.5A per square decimeter as a whole of the plated plate.

Embodiment 2

[0032] Prepare a kind of aqueous electrolytic bath that is suitable for plating zinc-nickel alloy, it contains the sodium hydroxide of 90g / L, the zinc ion of 8g / L, the nickel ion of 4g / L, the triethanolamine of 68g / L, the triethanolamine of 30g / L N,N,N',N'-tetrahydroxyisopropylethylenediamine, 12.5g / L of sodium silicate and 100mg / L of N,N'-bis[3-(dimethylamino)propyl] N-[2-hydroxy- Polymers of 3-(2-propenyloxy)propyl] derivatives. A bright steel Hull cell plate was plated at a current of 1 A in a Hull cell using a nickel anode for 30 minutes at a temperature of 30°C. The appearance of the plated plate is uniform and bright, with no visible defects. The deposit thicknesses and nickel alloy contents listed in Table 1 below were measured using a Fischerscope X-ray system XDL-B under conditions of current densities of 4A, 2A, and 0.5A per square decimeter as a whole of the plated plate.

Embodiment 3

[0034] Prepare a kind of aqueous electrolytic bath that is suitable for plating zinc-nickel alloy, it contains the potassium hydroxide of 120g / L, the zinc ion of 8g / L, the nickel ion of 4g / L, the triethanolamine of 68g / L, the triethanolamine of 30g / L N,N,N',N'-tetrahydroxyisopropylethylenediamine, 12.5g / L of sodium silicate and 100mg / L of N,N'-bis[3-(dimethylamino)propyl] N-[2-hydroxy- Polymers of 3-(2-propenyloxy)propyl] derivatives. A bright steel Hull cell plate was plated at a current of 1 A in a Hull cell using a nickel anode for 30 minutes at a temperature of 30°C. The appearance of the plated plate is uniform and bright, with no visible defects. The deposit thicknesses and nickel alloy contents listed in Table 1 below were measured using a Fischerscope X-ray system XDL-B under conditions of current densities of 4A, 2A, and 0.5A per square decimeter as a whole of the plated plate.

technical field

[0001] The present invention relates generally to improved methods of electrodepositing zinc-nickel alloys from aqueous alkaline plating baths, and novel additives for such electrodeposition methods. Background technique

[0002] Electrodeposition of zinc and zinc alloys based on alkaline plating baths has been known for many years. However, commercially acceptable deposits cannot be produced from pure sodium zincate electrolytes because such deposits are powdery and dendritic. Accordingly, various additives have been proposed to improve deposition, such as cyanide, which has significant environmental concerns, and polymers of amines and epichlorohydrin as grain refining additives. These polymers are limited to use in baths with relatively low zinc concentrations, since at higher metal concentrations uncontrolled deposition of zinc cannot be avoided. Also, electroplating processes using these additives tend to have poor cathode efficiency, narrow bright ran...

Examples

Embodiment 1

[0030] Prepare a kind of aqueous electrolytic bath that is suitable for plating zinc-nickel alloy, it contains the sodium hydroxide of 90g / L, the zinc ion of 8g / L, the nickel ion of 4g / L, the triethanolamine of 68g / L, the triethanolamine of 30g / L N,N,N',N'-tetrahydroxyisopropylethylenediamine, 12.5g / L of sodium silicate and 400mg / L of N,N'-bis[3-(dimethylamino)propyl] Polymer of urea and 1,1'-oxybis[2-chloroethane]. A bright steel Hull cell plate was plated at a current of 1 A in a Hull cell using a nickel anode for 20 minutes at a temperature of 30°C. The appearance of the plated plate is uniform and bright, with no visible defects. The deposit thicknesses and nickel alloy contents listed in Table 1 below were measured using a Fischerscope X-ray system XDL-B under conditions of current densities of 4A, 2A, and 0.5A per square decimeter as a whole of the plated plate.

Embodiment 2

[0032] Prepare a kind of aqueous electrolytic bath that is suitable for plating zinc-nickel alloy, it contains the sodium hydroxide of 90g / L, the zinc ion of 8g / L, the nickel ion of 4g / L, the triethanolamine of 68g / L, the triethanolamine of 30g / L N,N,N',N'-tetrahydroxyisopropylethylenediamine, 12.5g / L of sodium silicate and 100mg / L of N,N'-bis[3-(dimethylamino)propyl] N-[2-hydroxy- Polymers of 3-(2-propenyloxy)propyl] derivatives. A bright steel Hull cell plate was plated at a current of 1 A in a Hull cell using a nickel anode for 30 minutes at a temperature of 30°C. The appearance of the plated plate is uniform and bright, with no visible defects. The deposit thicknesses and nickel alloy contents listed in Table 1 below were measured using a Fischerscope X-ray system XDL-B under conditions of current densities of 4A, 2A, and 0.5A per square decimeter as a whole of the plated plate.

Embodiment 3

[0034] Prepare a kind of aqueous electrolytic bath that is suitable for plating zinc-nickel alloy, it contains the potassium hydroxide of 120g / L, the zinc ion of 8g / L, the nickel ion of 4g / L, the triethanolamine of 68g / L, the triethanolamine of 30g / L N,N,N',N'-tetrahydroxyisopropylethylenediamine, 12.5g / L of sodium silicate and 100mg / L of N,N'-bis[3-(dimethylamino)propyl] N-[2-hydroxy- Polymers of 3-(2-propenyloxy)propyl] derivatives. A bright steel Hull cell plate was plated at a current of 1 A in a Hull cell using a nickel anode for 30 minutes at a temperature of 30°C. The appearance of the plated plate is uniform and bright, with no visible defects. The deposit thicknesses and nickel alloy contents listed in Table 1 below were measured using a Fischerscope X-ray system XDL-B under conditions of current densities of 4A, 2A, and 0.5A per square decimeter as a whole of the plated plate.

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