Contribution to the elucidation of corrosion initiation through confocal laser scanning microscopy (CLSM)

In this work, an electrochemical minicell has been developed to study the microscopic changes that occur on the electrode surface at the first steps of the corrosion process by means of optical and confocal laser scanning microscopy. Duplex stainless steel (UNS 1.4462) specimens (1.6 mm in diameter) have been used to check this technique. It has been observed that the corrosion process happens in a sequential way: first, a pit appears on the tested surface; later, the corrosion product spreads and catalyzes new corrosion processes. The spread corrosion product grows in a three-dimensional way. The used technique has demonstrated to be very useful for the observation of the initiation of corrosion processes.