Analysis of Metal Corrosion

Abstract

Ion beam and nuclear techniques are well suited for a variety of measurements on chemical elements contained in surface and near-surface regions of a sample and, as such, are a valuable tool for studying the processes by which metals corrode. For metals and corrosion films, the methods are generally nondestructive so that measurements can be interspersed with sample exposures to the corroding environment or with any other treatments or measurements that may be desired. Rutherford backscattering and nuclear resonance reaction techniques can be used to measure impurity depth concentration profiles with depth resolutions of less than 100 angstroms for the topmost layers of a surface and a few hundreds of angstroms for deeper layers. Microbeams can be used to study impurities and compositional variations in the plane of the surface with spatial resolutions of better than 5 microns. Nuclear reaction methods are capable of measuring not only the amount of a given chemical element present but also of specific isotopes of that element. It is possible with these methods therefore to use stable isotope tracers for studying atomic transport and surface reaction mechanisms. The elements important in metal corrosion processes can all be studied with ion beam and nuclear techniques. The reaction to use for a specific analysis problem will depend on the interferences to be expected from the sample, on the sensitivity and accuracy needed, and on the kind of information required.