IN-SITU SYNCHROTRON-RADIATION X-RAY TECHNIQUES FOR STUDIES OF CORROSION AND PROTECTION

The importance of synchrotron radiation X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) as probes for the characterisation of corrosion products, surface films and protective layers is emphasised. In many cases, in situ studies may be carried out to elucidate structural information about the surface of an electrode in the presence of an intact surface film and the electrolyte under controlled potential conditions. The versatility of these X-ray techniques in corrosion and protection is illustrated by the following systems (and X-ray techniques): the phase composition of phosphate coatings on carbon steel (ex situ XRD), phase transformation of lead dioxide films in 1 M H2SO4 during potential cycling (in situ XRD) and the structure of passive films on iron in 0.1 M NaClO4 at constant potential (in situ XAS).