Study of the pitting and repassiv,tion corrosion potential of zicaloy-4 halides solutions at 250C and several pH

The electrochemical behaviour of Zircaloy-4 electrode in chloride, bromide and iodide acid solution was investigated at 250C employing stationary, quasi-stationary and potentiodynamic techniques. The results show that the pitting and repassivation potentials are independent on pH but both are dependent on halice concentration, following linear relation ships in these cases. It is also possible to correlate the pitting potential with the ionic radius of the anions, allowing thus to establish an order in their agressive properties. This order was extrapolated for fluoride ion and further experimental measurements show that the corrosion potential of Zircaloy-4 in acid or neutra solution of this ion (which undergoes active dissolution) is coincident with that predicted from the Ep v/s ionic radius determined for the other halides. (Author)