THE GROWTH OF A PASSIVE FILM ON STEEL STUDIED WITH IN-SITU AFM
Free (open access)
23 - 29
GERRIT ZIJLSTRA, ENNE T. FABER, VÁCLAV OCELÍK, JEFF TH. M. DE HOSSON
The passive film on stainless steel is a crucial barrier to retard or block further corrosion of the bulk. After damage due to fabrication processes or during use in service, the passive film has to be recovered. Little is known of the characteristic time scale of the passivation process in ambient conditions, i.e. air. In this work, a quantitative method is presented to follow the growth of the passive layer after damage, in-situ by AFM. The passive layer of a defined area is removed by sputtering with argon ions. The recovery of the film is measured by recording the height difference between the sputtered area and the reference area using AFM. The growth of the new passive film is terminated after 2 hours. The height difference of the passive film and the substrate is measured 25 minutes after exposure to air and extrapolated to be 21 nanometers at the onset of passivation. This thickness agrees rather well with the calculated range of 18.9 to 21.5 nanometers.
steel, recovery, AFM, oxidation, iron, chromium, passive layer, thin film