Abstract
The effect of ammonium bifluoride as an addition agent to the bath composed of ferrous sulfamate and sulfamic acid for iron deposition was studied.
Furthermore, the effects of the concentration of ferrous ion, amount of the addition agent, pH, cathodic current density, and bath temperature on current efficiency and surface state of the deposited iron were also investigated.
As the results, the optimum conditions found were as follows.
Bath composition: ferrous ion 95g/l
saccharin 0.1g/l
ammonium bifluoride 10g/l
pH3.0
Depositing conditions: bath temperature 60-70°C
cathodic current density 5-10Amp./dm2
Under the above conditions, the current efficiency was 75-85% and the deposition rate was varied with the current efficiency, but was calculated to be in the range of 40-110μ/hr. The throwing power of the bath was nearly equal to that of copper sulfate bath.
The deposit of up to 0.5mm thick had a non-bright rugged surface, but its structure showed uniform appearance with no cracks or pits. Therefore, the addition agent, ammonium bifluoride, had an effect of preventing cracks or pits, but no effect on improving brightness.
