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