Kinetics of oxidation of metals in the air at room temperature using EDX

The kinetics of oxidation of Zn, Cu, Ni and C. steel were studied using the surface techniques, SEM, EDX and XRD,
and electrochemical impedance spectroscopy (EIS) technique. EDX results showed that the variation of weight
percent oxygen (Wt% O) on the surface of the four metals with the exposure time gave the same behavior, there
is an increase of Wt% O with increasing the exposure time until about 2 h followed by a plateau, then the Wt% O
increases again with increasing the time of exposure than 4 h. Fitting the experimental data of the four metals to
the kinetic laws of oxidation indicated that the logarithmic law was fitted in short exposure (0.5 – 4 h), however,
the parabolic law was fitted in long exposure (6 – 10 h). The values of each logarithmic rate constant (kl) and
parabolic rate constant (kp)for the four metals were calculated. The kinetic of oxidation of the metals under
study with exposure time is confirmed utilizing XRD technique. The protective action of the air-formed oxide
films was investigated by EIS technique. The electrochemical impedance spectroscopy results confirmed the EDX
results.