Electrochemical aspects of the electroforming of iron
2013-02-22T14:13:23Z (GMT) by
The patent literature describing the development of the foil electroforming technology has been reviewed. A review of the literature covering the development of iron plating electrolytes has also been completed. A detailed study of the effects of solution parameters on the conductivity of iron chloride solution and the effect of addition of a number of 'conductivity salts' has been carried out. The operation of a pilot plant for the continuous production of iron foil has. been investigated and the parameters of foil production characterised. Preliminary cathodic polarization studies were made at low current densities on the iron chloride electrolyte showing the effects of temperature on the system. A number of possible materials for use as insoluble anodes have been investigated using anodic polarization to determine· their behaviour in the aggressive hot iron chloride electrolyte environment. The possibility of reducing depassivation of the cathode by the addition of a less aggressive anion was studied but no significant improvement achieved. For a more detailed and controlled study of the hot iron chloride electrolyte, a closed, divided-cell incorporating a rotating-cylinder electrode was designed and constructed to operate near to the boiling polnt.of the electrolyte. The cell enabled a more rigorous-study of the electrolyte to be made as the solution parameters could be better controlled. The concentration of the ferric ion in the solution could be reduced and held constant while other factors could be measured. This system has been used to demonstrate the electrochemical reduction of ferric ion in addition to demonstrating that chemical reduction of the electrolyte was feasible and to study the effect of ferric ion concentration on cathode current efficiency. Control of ferric ion concentration by use of the divided cell has also enabled study of some of the deposition characteristics, the effects of stirring on the deposit and an investigation into the use of surface-active agents in further optimising the electrolyte performance.