Study of the initial stage of white rust formation on zinc single crystal by EIS, STM/AFM and SEM/EDS techniques

摘要

The kinetic consequences of morphological changes due to the zinc exchange process have been related to the corrosion performance and a further understanding of the initial stage of the white rust formation occurring preferentially in a thin layer of moisture in the absence of oxygen. Electrochemical impedance diagrams for a uniformly covered Zn corrosion product layer can be interpreted by a one-step dissolution mechanism, while on a non-uniform, partially active surface a consecutive dissolution occurs via adsorbed Zn(I) and Zn(II) species. The in situ EC-STM and EC-AFM observations revealed oriented Zn dissolution, deposition along the atomic steps and oriented oxide formation on the redeposited crystal planes in the early stages of each process.