Mass transport control of localised corrosion processes: in situ local probing and modelling

In this paper, the importance of mass transport in localised corrosion process is demonstrated using two examples describing the corrosion behaviour of two types of cut-edge electrodes regarding, (i) the sacrificial dissolution of a sacrificial Zn coating on steel (galvanised steel) and (ii) the release of inhibitors from a primer on an aluminium alloy (AA2024). In the two cases, in situ pH imaging with an ion-selective microprobe is used to confirm, (i) the role of corrosion products on the galvanic current profiles and (ii) the competition between the inhibition and the triggering of the local corrosion activity around intermetallic particles. It is illustrated how the experimental results can be supported by a 2D mass transport modelling.