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.
A Doctoral Thesis. Submitted in partial fulfilment of the requirements for the award of Doctor of Philosophy of Loughborough University.