Sunday, March 30, 2008

Nickel Cobalt Baths

Nickel cobalt alloy deposits have been used for a number of engineering or functional applications. A bath used for the production of nickel electrotypes in the graphic arts industry is given in the table. Deposits are hard but have ample ductility to withstand distortion normally encountered in press operations. There has been a considerable increase in the use of high cobalt nickel plating on bronze magnetic tapes used in calculating machines, automatic ticket machines, and other electronic devices. For these uses, the preferred composition of the deposits is 20% nickel, 80% cobalt. The bath is a mixture of nickel and cobalt sulfates and chlorides maintained at a pH of about 3 and a temperature of 61oC. To obtained the desired magnetic properties and uniformity, the superimposition of alternating current on a steady direct current has been employed. A high internal stress has also been found to favor proper magnetic properties.


Nickel cobalt alloy plate from sulfamate baths has received considerable study. These alloys retain their strength and hardness on heating which is important for electroforms that have to stand heating up to 620oC.





Type
Ingredients
C, g/l
pH
T, oC
Watts
Nickel Sulfate, NiSO4.6H2O
Nickel Chloride, NiCl2.6H2O
Boric Acid, H3BO3
330
45
38
1.5-4.5
45-65
Hard
Nickel Sulfate, NiSO4.6H2O
Ammonium Chloride, NH4Cl
Boric Acid, H3BO3
180
25
30
5.6-5.9
43-60
Chloride
Nickel Chloride, NiCl2.6H2O
Boric Acid, H3BO3
300
38
2.0
50-70
Chloride
Sulfate
Nickel Sulfate, NiSO4.6H2O
Nickel Chloride, NiCl2.6H2O
Boric Acid, H3BO3
200
175
40
1.5-2.0
45
Chloride
Acetate
Nickel Chloride, NiCl2.6H2O
Nickel Acetate,
Ni(C2H3O2)2.4 H2O
135
105
4.5-4.9
30-50
Nickel
Cobalt
Nickel Sulfate, NiSO4.6H2O
Nickel Chloride, NiCl2.6H2O
Boric Acid, H3BO3
Ammonium Sulfate, (NH4)2SO4
Nickel Formate, Ni(CHO2)2.2H2O
Cobalt Sulfate, CoSO4.7H2O
240
22.5
30
1.5
15
2.6
4.7
40
Flouborate
Nickel (as Flouborate)
Free Flouboric Acid, HBF4
Free Boric Acid, H3BO3
75
3.7-37.5
30
2.0-3.5
40-80
Sulfamate
Nickel Sulfamate, Ni(NH2SO3)2
Boric Acid, H3BO3
450
30
3.0-5.0
40-60
Sulfamate
Chloride
Nickel Sulfamate, Ni(NH2SO3)2
Nickel Chloride, NiCl2.6H2O
Boric Acid, H3BO3
300
6
30
3.5-4.2
28-60



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