## 3 Results and Discussion
### The Effects of CS Immersion in Fire Extinguishing Solution
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Imersion Time**} & \multirow{2}{*}{\(\mathbf{R_{s}}\)} & \multirow{2}{*}{\(\mathbf{C_{ext}}\)} & \multirow{2}{*}{\(\mathbf{R_{ext}}\)} & \multicolumn{2}{c}{**CPE**} & \multirow{2}{*}{\(\mathbf{R_{\text{in}}}\)} & \multirow{2}{*}{\(\mathbf{C_{dl}}\)} & \multirow{2}{*}{\(\mathbf{R_{ct}}\)} & \multirow{2}{*}{\(\mathbf{10^{3}\chi^{2}}\)} & \multirow{2}{*}{\(\mathbf{\epsilon_{Z}}\)} \\  & \(\mathbf{\Omega\cdot cm^{2}}\) & \(\mathbf{\mu f/cm^{2}}\) & & \(\mathbf{\Omega\cdot cm^{2}}\) & & & & & \\ \cline{6-10}  & & & & & & & & & \\ \hline
36 days & 4.56 & 12.32 & 2.02 & 6.07 \(\times\) 10\({}^{-4}\) & 0.700 & 409 & 21.28 & 6707 & 2.21 & 4.78 \\
78 days & 4.83 & 16.98 & 3.00 & 8.96 \(\times\) 10\({}^{-4}\) & 0.619 & 494 & 5.211 & 8613 & 0.696 & 2.63 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Equivalent circuit element values for ZnPS immersed for long periods in FES. Figure 8: The equivalent circuit used in the analysis of EIS data for ZnPS immersed in FES for (**a**) 1 h or (**b**) 36/78 days. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Imersion Time**} & \multirow{2}{*}{\(\mathbf{R_{s}}\)} & \multicolumn{2}{c}{**CPE1**} & \multirow{2}{*}{\(\mathbf{R_{ext}}\)} & \multicolumn{2}{c}{**CPE2**} & \multirow{2}{*}{\(\mathbf{R_{ct}}\)} & \multirow{2}{*}{\(\mathbf{10^{3}\chi^{2}}\)} & \multirow{2}{*}{\(\mathbf{\epsilon_{Z}}\)} \\  & & & & & & & & & & \\ \cline{6-10}  & \(\mathbf{\Omega\cdot cm^{2}}\) & & & & & & & & \\ \cline{6-10}  & \(\mathbf{\Omega\cdot cm^{2}}\) & & & & & & & & \\ \hline
1 h & 4.64 & 3.80 \(\times\) 10\({}^{-4}\) & 0.634 & 282.8 & 2.03 \(\times\) 10\({}^{-3}\) & 0.533 & 989 & 2.26 & 4.75 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Equivalent circuit element values for ZnPS immersed for 1 h in FES. * The outer layer was porous and had very low resistance, which did not vary appreciably with the immersion time, and the capacity was also small and weakly influenced by the immersion time;
* The resistance of the phosphate layer increased with the immersion period; from 283 at the initial moment to 494 after 78 days of immersion, probably due to pores clogging with oxides/corrosion products [20]; and
* The presence of two layers in which the clogging of the pores takes place, leading, in time, to a very high increase in the charge transfer resistance and consequently to the passivation of the alloy. The general appearance of the sample and two details on the surface are presented in Figure 7. The surface of the sample was covered with a seemingly homogeneous crust (zone A) and a portion of this crust was damaged (zone B). In the center of the sample, the crust was convex (zone C) without being damaged. The outer layer was largely formed by adsorption of FES and corrosion products accumulated under this layer. Because they could not pass through it completely, it created pressure and deformed. It thus appears that zone B appeared as a result of the eruption of the crust under the pressure of the products inside. In Figure 9, it can be observed that the partially uncovered area was much rougher than the continuous crust (zone A). The average compositions in these two areas, determined by EDS microanalysis, are shown in Figure 10. It can be seen that in both areas, the elements of the FES predominated, which also contained corrosion products (probably FeOOH). The distribution of the elements in that areas is presented in Figures 11 and 12. According to the data in Figure 10 and the elemental mapping in Figures 11 and 12 the following observations can be made:  
* The amount of oxygen in both areas was very high, therefore, if the concentration of iron oxides is considered relatively small, the high amount of oxygen can be attributed only to FES molecules adsorbed on the surface;
* The percentages of oxygen and carbon were higher in zone B than in zone A and the amount of iron was almost half in zone B compared to that in zone A.