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Swelling of steel film by hydrogen absorption at cathodic potential in electrolyte

DOI: 10.1002/pssb.202000055 DOI Help

Authors: Debi Garai (Diamond Light Source; Amity University) , Ilaria Carlomagno (Universitá Roma Tre) , Vladyslav Solokha (Diamond Light Source; Johannes Kepler University Linz) , Axel Wilson (Diamond Light Source) , Carlo Meneghini (Universitá Roma Tre) , Christian Morawe (ESRF – The European Synchrotron) , Vadim Murzin (University Wuppertal) , Ajay Gupta (Amity University) , Jorg Zegenhagen (Diamond Light Source)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Physica Status Solidi (b) , VOL 3

State: Published (Approved)
Published: April 2020

Open Access Open Access

Abstract: An ≈4 nm FeCrNi film, deposited on a Ru/B4C multilayer (ML), is used to study cathodic hydrogen charging in electrolyte. A thin film on a ML allows obtaining precise quantitative information on surface metal composition and oxidation state using the X‐ray standing wave technique combined with near‐edge X‐ray absorption spectroscopy. The metal composition is found being close to the composition of stainless steel (SS) 304, and, as for bulk steel, the outer 2 nm passive layer, consisting of oxidized iron and chromium, is depleted of nickel. Overall, it is found that the film represented a useful replica of the surface of bulk steel. Following exposure to 0.1 m KCl electrolyte at −0.6 V versus Ag/AgCl, 11.3 (±3)% swelling of the film by hydrogen absorption is observed. The estimated absorbed amount is exceeding reported bulk absorption under similar conditions by more than an order of magnitude. Strong hydrogen absorption appears to be enabled by the 2D character of the thin film, i.e., a significantly lower associated strain energy compared with bulk absorption. The strong surface swelling is suggested to be related to the lowering of the pitting corrosion resistance of SS surfaces reported following hydrogen exposure.

Journal Keywords: hydrogen loading; stainless steels; thin films; X-ray spectroscopy; X-ray standing waves

Subject Areas: Chemistry, Materials

Instruments: B16-Test Beamline , B18-Core EXAFS

Other Facilities: PETRA-III, DESY