As for SS, the radius of the Nyquist diagram (Fig. 8a) is much larger than that of BS. The impedance magnitude of SS is nearly 3 A 83-01 higher than that of BS in low frequency range (Fig. 8c). As previously mentioned, SS is covered with a composite film with air trapped in it. As a result, two time constants appear in frequency ranges of 102–104 Hz and 0.1–1 Hz (Fig. 8b), which correspond to the superhydrophobic film penetrated by the NaCl solution and the corroding interface, respectively. The corrosion behavior of SS can be analyzed through the equivalent circuit shown in the inset of Fig. 8b. In this circuit, the superhydrophobic film of SS is characterized by a parallel combination of a film constant phase element CPEf and a film resistance Rf, and the corroding interface is characterized by a parallel combination of a double layer constant phase element CPEdl and a charge transfer resistance Rct. The fitted electrochemical parameters of BS and SS are summarized in Table 2.