## 3 Results and Discussion
### Evaluation of the Self-Healing Ability of the Coatings
#### 3.7.2 Evaluation of the Self-Healing Ability by EIS Tests in NaCl and HCl Solutions
These results are in good agreement with the Nyquist plots, according to the fact that samples C and B have the highest total impedance for NaCl and HCl immersion solutions, respectively. According to these results, it can be concluded that the released CAR was not enough to protect the scratched area for sample B in NaCl solution. However, for the HCl media, the \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Sample** & **R\({}_{\text{s}}\)** & **CPE\({}_{\text{coat-T (s}}\)** & **CPE\({}_{\text{coat-P}}\)** & **R\({}_{\text{coat}}\)** & **CPE\({}_{\text{al-T (s}}\)** & **CPE\({}_{\text{dl-P}}\)** & **R\({}_{\text{corr}}\)** \\
**Code** & **(\(\Omega\) cm\({}^{2}\))** & **\(\Omega^{-1}\) cm\({}^{-2}\))** & **CPE\({}_{\text{coat-P}}\)** & **(\(\Omega\) cm\({}^{2}\))** & **(\(\Omega^{-1}\) cm\({}^{-2}\))** & **CPE\({}_{\text{dl-P}}\)** & **(\(\Omega\) cm\({}^{2}\))** \\ \hline A & 2.43\(\times 10^{2}\) & 1.14\(\times 10^{-9}\) & 9.04\(\times 10^{-1}\) & 234.10 & 6.38\(\times 10^{-5}\) & 5.15\(\times 10^{-1}\) & 2.05\(\times 10^{3}\) \\ B & 421.20 & 1.63\(\times 10^{-9}\) & 9.85\(\times 10^{-1}\) & 476.60 & 2.00\(\times 10^{-5}\) & 7.51\(\times 10^{-1}\) & 4.07\(\times 10^{4}\) \\ C & 4.00\(\times 10^{3}\) & 1.45\(\times 10^{-9}\) & 9.90\(\times 10^{-1}\) & 2.21\(\times 10^{3}\) & 1.51\(\times 10^{-5}\) & 6.90\(\times 10^{-1}\) & 1.01\(\times 10^{4}\) \\ D & 25.61 & 2.95\(\times 10^{-10}\) & 9.90\(\times 10^{-1}\) & 227.80 & 6.41\(\times 10^{-5}\) & 4.97\(\times 10^{-1}\) & 2.38\(\times 10^{3}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 4: The EIS parameters for the scratched coatings and immersed in the 0.5 M HCl. Figure 10: Employed electrical equivalent circuit for the fitting of the Nyquist and bode curves. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Sample** & **R\({}_{\text{s}}\)** & **CPE\({}_{\text{coat-T (s}}\)** & **CPE\({}_{\text{coat-P}}\)** & **R\({}_{\text{coat}}\)** & **CPE\({}_{\text{dl-T (s}}\)** & **R\({}_{\text{corr}}\)** \\
**Code** & **(\(\Omega\) cm\({}^{2}\))** & **\(\Omega^{-1}\) cm\({}^{-2}\))** & **CPE\({}_{\text{coat-P}}\)** & **(\(\Omega\) cm\({}^{2}\))** & **(\(\Omega^{-1}\) cm\({}^{-2}\))** & **CPE\({}_{\text{dl-P}}\)** & **(\(\Omega\) cm\({}^{2}\))** \\ \hline A & 129.60 & 1.05\(\times 10^{-4}\) & 5.44\(\times 10^{-1}\) & 276.2 & 1.03\(\times 10^{-4}\) & 5.64\(\times 10^{-1}\) & 6.62\(\times 10^{3}\) \\ B & 353.60 & 6.89\(\times 10^{-6}\) & 7.92\(\times 10^{-1}\) & 611 & 1.94\(\times 10^{-5}\) & 7.38\(\times 10^{-1}\) & 4.19\(\times 10^{4}\) \\ C & 847.30 & 1.20\(\times 10^{-9}\) & 9.77\(\times 10^{-1}\) & 3.77\(\times 10^{4}\) & 4.44\(\times 10^{-7}\) & 6.32\(\times 10^{-1}\) & 6.97\(\times 10^{5}\) \\ D & 875.40 & 1.03\(\times 10^{-7}\) & 5.92\(\times 10^{-1}\) & 2.69\(\times 10^{3}\) & 1.75\(\times 10^{-6}\) & 6.97\(\times 10^{-1}\) & 1.05\(\times 10^{5}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Electrochemical impedance spectroscopy (EIS) parameters for the scratched coatings and immersed in the 3.5 wt.% NaCl. corrosion resistance and barrier property of the coating are more sensitive to particle agglomeration and the adhesion of the coatings. In fact, the increase in the nanocapsules content decreased the adhesion of the coating and made it more susceptible to the penetration of the corrosive ions to the metallic substrate in the acidic media. On the other hand, the hydrogen ion possibly catalyzed the healing reaction between epoxy and CAR functional groups at the initial release of CAR. Since the healing reaction and healing solidification is accelerated, fewer healing agents were allowed to release. Consequently, the healing reaction in the acidic media is less sensitive to the available healing agent and is mostly controlled by the adhesion of the coatings to the metallic substrate. Therefore, for the scratched samples immersed in the HCl solution, the highest self-healing performance was observed for sample B.