Theoretical and experimental study of the interaction of O2 and H2O with metallic zinc--discussion of the initial step of oxide formation

The steps of Zn corrosion and ZnO formation using dry O2 or O2/water atmosphere were investigated in situ using an experimental and theoretical approach. The adsorption equilibrium and kinetics of O2/H2O on Zn have been measured at different temperatures and relative humidities using a Cahn 1000 vacuum recording electrobalance. The amounts adsorbed on Zn are different in the presence or absence of O2. SEM-EDAX, XPS, and XRD studies have been performed at the surface for different times of reaction. A theoretical study using the extended Hückel method has been done for the adsorption/reaction of H2O/O2 on Zn and on ZnO. A coherent explanation is presented for the initial steps of ZnO formation on Zn, for the steady state found for the ZnO growth, and for the experimental findings of the methods cited above.