Chemical degradation of selected Zn-based corrosion products induced by C60 cluster, Ar cluster and Ar+ ion sputtering in the focus of X-ray photoelectron spectroscopy (XPS)

Monoatomic ion sputtering is a common concept for surface sensitive analysis methods to clean surfaces prior investigation or to obtain information from deeper regions. However, severe damage of the materials - linked to preferential sputtering, ion implantation, atomic mixing and in worst case chemical degradation - can affect the validity of the analysis. Hence, the impact of C-60 cluster etching, furthermore, of Ar+ ion bombardment with and without azimuthal sample rotation and also the application of heavy projectiles (Xe+ ions) was investigated to find a concept, which is less destructive or with less critical influence on the chemical nature of the investigated materials. In this work the focus is set on hydrozincite and zinc oxide, two common corrosion products of Zn-based coatings. As a main point, all the obtained results from (i)Ar+ ion, (ii) Ar cluster, and (iii) C-60 cluster etching on the degradation kinetics of hydrozincite were compared with respect to the reached sputter depth. In addition, the sputter rate of all three methods was experimentally determined for ZnO. In total, fully non-destructive conditions could not be found, but valuable knowledge on the type and rate of degradation, which is essential to choose the most suited sputter concept. (C) 2017 Elsevier B.V. All rights reserved.