In-situ investigation of corrosion by neutron reflectometry – Formation, growth and failure of protective oxide films on metals

Research Project, 2019 – 2023

We will apply in-situ neutron reflectometry (NR) on two corrosion problems, investigating; a) the penetration of thin oxide films on Mg and MgAl by water/hydrogen under ambient conditions and b) how hydrogen in FeCr steel affects the growth of protective surface oxide layers at high temperature. In both cases we use in situ NR to study processes at the interface between a continuous surface oxide and the underlying metal, focusing on the role of hydrogen. Subsurface regions are difficult to access in situ by other analytical techniques, limiting the scientist to analyzing after the experiment. Post-analysis for hydrogen has many inherent limitations because it is easily lost during specimen preparation or in the analysis itself. Detection of hydrogen by NR is doable because the changes in neutron scattering density related to hydrogen uptake are expected to affect much of the interfacial region. Corrosion problems of this type have not been addressed by NR previously. To provide meaningful input to the corrosion problems selected, the NR measurements are complemented by a range of other analytical approaches (mainly Post-analysis). In addition to the scientific problems addressed, this proposal attempts to widening the scope of NR usage by learning about the challenges involved in employing NR on corrosion processes at both ambient and high temperature. This will help build industry interest for neutron science, preparing for the advent of ESS.