Pit formation in relation to the etching of aluminium in chloride solutions

Abstract

The pitting potential,E _p , has been determined by steady-state and linear potential sweep methods.E _p is is shown to be a logarithmic function of the chloride concentration; the form of the function yields information about the equilibria between electrode and electrolyte species atE _p . Values of the enthalpy of activation for the pitting process have been determined by measuring the rate of pit propagation at constant driving potential at a series of temperatures. An ‘ad hoc’ interpretation of the data has been avoided and an attempt made to present the results using a more theoretical approach.