Pulse electroplating process

A process of producing a rhodium electrodeposit by pulse current electroplating in which the electrolyte comprises rhodium sulfate and sulfuric acid with a rhodium metal concentration of from 3 to 10 g/L and a sulfuric acid concentration of from 50 to 150 mL concentrated (95-98%) sulfuric acid per liter, and an on/off pulse time ratio of 1:4.5, and an on-time of from 0.05 to 0.5 ms and an off-time of from 0.45 to 4.5 ms and a peak current density of from 10 to 1,600 mA/cm.sup.2.

A process of producing a rhodium electrodeposit by pulse current electroplating in which the electrolyte comprises rhodium sulfate and sulfuric acid with a rhodium metal concentration of from 3 to 5 g/L and a sulfuric acid concentration of from 100 to 150 mL concentrated (95-98%) sulfuric acid per liter, and on/off pulse time ratio of from 1:9, and an on-time of from 0.1 to 0.3 ms and an off-time of from 0.9 to 2.7 ms and a peak current density of from 10 to 800 mA/cm.sup.2.

A process of producing a rhodium-sheet or foil by pulse current electroplating in which the electrolyte comprises rhodium sulfate and sulfuric acid with a rhodium metal concentration of from 1 to 20 g/L and a sulfuric acid concentration of from 25 to 200 mL concentrated (95-98%) sulfuric acid per liter, and on/off pulse time ratio of from 1:20 to 1:4.5, with an on-time of from 0.05 to 0.8 ms and an off-time of from 0.45 to 7.2 ms and a peak current density of from 5 to 3,200 mA/cm.sup.2, and the process includes the steps of plating the rhodium onto a brass substrate and when the rhodium has been deposited to the desired thickness dissolving away the brass using nitric acid.