Electrolyte composition and method for the deposition of a zinc-nickel alloy layer on a cast iron or steel substrate

1. A method for the deposition of a zinc-nickel alloy layer on a substrate comprising:

contacting a substrate of cast iron or steel with an electrolytic composition comprising a source of zinc ions, a source of nickel ions, aminoacetic acid, and an acetate selected from the group consisting of sodium acetate, potassium acetate, ammonium acetate, and mixtures thereof, wherein the acetate and aminoacetic acid are present in a molar ratio of acetate:aminoacetic acid between about 0.35:1 and about 0.91:1; and

applying a current to form the zinc-nickel alloy layer having a nickel content of between 10 and 18 wt % on the substrate and substantially no internal tension.

2. The method of claim 1 wherein the electrolytic composition further comprises a potassium halide.

3. The method of claim 1 wherein the electrolytic further comprises potassium chloride.

4. The method of claim 1 wherein the electrolytic composition comprises 10 to 50 g/L of the aminoacetic acid.

5. The method of claim 1 wherein the electrolytic composition further comprises boric acid.

6. The method of claim 1 wherein the electrolytic composition further comprises potassium chloride and boric acid.

7. The method of claim 1 wherein the electrolytic composition further comprises from 190 to 220 g/L potassium chloride.

8. The method of claim 1 wherein the electrolytic composition further comprises 10 to 30 g/L boric acid.

9. The method of claim 1 wherein the electrolytic composition further comprises from 190 to 220 g/L potassium chloride and from 10 to 30 g/L boric acid.

10. The method of claim 1 wherein the contacting is at a temperature between 30° C. and 40° C.

11. The method of claim 1 wherein the current has a current density between about 0.5 and about 5 A/dm 2 .

12. The method of claim 1 wherein the current has a current density between 1.0 and 3.5 A/dm 2 .

13. The method of claim 1 wherein the current has a density between 1.0 and 3.5 A/dm 2 , and the electrolytic composition has a pH between 5 and 6 and comprises:

zinc chloride:

60-70

g/L

nickel chloride × 6H 2 O:

100-130

g/L

potassium chloride:

190-220

g/L

boric acid:

15-20

g/L

sodium acetate × 3H 2 O:

25

g/L

aminoacetic acid:

30

g/L

sodium saccharine:

2-4

g/L

benzal acetone:

0.025-0.2

g/L

orthochlorobenzaldehyde:

0.006-0.01

g/L

octanolethoxylate:

0.8 to 1.2

g/L

potassium salt of sulfopropylated polyalkoxylated

2.5 to 3.2

g/L.

naphthol:

14. The method of claim 1 wherein the current has a density between 1.0 and 3.5 A/dm 2 , and the electrolytic composition has a pH between 5 and 6 and comprises:

zinc chloride:

60-70

g/L

nickel chloride × 6H 2 O:

100-130

g/L

potassium chloride:

190-220

g/L

boric acid:

15-20

g/L

sodium acetate × 3H 2 O:

25

g/L

aminoacetic acid:

30

g/L

sodium saccharine:

2-4

g/L

benzal acetone:

0.025-0.05

g/L

pyridine sulphonic acid:

0.5-1.0

g/L

octanolethoxylate:

0.8 to 1.2

g/L

potassium salt of sulfopropylated polyalkoxylated

2.5 to 3.2

g/L.

naphthol:

15. The method of claim 1 wherein the current has a density between 0.5 and 1.0 A/dm 2 , and the electrolytic composition has a pH between 5 and 6 and comprises:

zinc chloride:

60-76

g/L

nickel chloride × 6H 2 O:

100-130

g/L

potassium chloride:

190-220

g/L

boric acid:

15-20

g/L

potassium acetate:

25

g/L

aminoacetic acid:

30

g/L

sodium saccharine:

2-4

g/L

benzal acetone:

0.025-0.05

g/L

orthochlorobenzaldehyde:

0.008-0.12

g/L

octanolethoxylate:

0.8 to 1.2

g/L

potassium salt of sulfopropylated polyalkoxylated

2.5 to 3.2

g/L.

naphthol:

16. The method of claim 1 wherein the current has a density between 1.0 and 3.5 A/dm 2 , and the electrolytic composition has a pH between 5 and 6 and comprises:

zinc chloride:

60-70

g/L

nickel chloride × 6H 2 O:

100-130

g/L

potassium chloride:

190-220

g/L

boric acid:

15-20

g/L

sodium acetate × 3H 2 O:

25

g/L

aminoacetic acid:

30

g/L

sodium saccharine:

2-4

g/L

octanolethoxylate:

0.8 to 1.2

g/L

a brightener system comprising a brightener selected from the group consisting of benzal acetone, orthochlorobenzaldehyde, potassium salt of sulfopropylated polyalkoxylated naphthol, pyridine sulfonic acid, and combinations thereof.

17. The method of claim 1 wherein the current has a density between 1.0 and 3.5 A/dm 2 , and the electrolytic composition has a pH between 5 and 6 and consists essentially of:

zinc chloride:

60-70

g/L

nickel chloride × 6H 2 O:

100-130

g/L

potassium chloride:

190-220

g/L

boric acid:

15-20

g/L

sodium acetate × 3H 2 O:

25

g/L

aminoacetic acid:

30

g/L

sodium saccharine:

2-4

g/L

benzal acetone:

0.025-0.2

g/L

orthochlorobenzaldehyde:

0.006-0.01

g/L

octanolethoxylate:

0.8 to 1.2

g/L

potassium salt of sulfopropylated polyalkoxylated

2.5 to 3.2

g/L.

naphthol:

18. The method of claim 1 wherein the current has a density between 1.0 and 3.5 A/dm 2 , and the electrolytic composition has a pH between 5 and 6 and consists essentially of:

zinc chloride:

60-70

g/L

nickel chloride × 6H 2 O:

100-130

g/L

potassium chloride:

190-220

g/L

boric acid:

15-20

g/L

sodium acetate × 3H 2 O:

25

g/L

aminoacetic acid:

30

g/L

sodium saccharine:

2-4

g/L

octanolethoxylate:

0.8 to 1.2

g/L

a brightener system comprising a brightener selected from the group consisting of benzal acetone, orthochlorobenzaldehyde, potassium salt of sulfopropylated polyalkoxylated naphthol, pyridine sulfonic acid, and combinations thereof.