## 4 Results and Discussion
### Electrochemical Impedance Spectroscopy Measurements
#### 4.1.2 Mixture with Lithium Content (LiNaK)NO\({}_{3}\) Testing  
Subsequently, the Nyquist diagrams for the ternary salt with lithium content (LiNaK)NO\({}_{3}\) are shown in Figures 10-12 for the AISI 304 and AISI 430 stainless steels, as well as for the nickel-based alloy HR-224, respectively. The measurements were made after 2, 4, 6, 8, 24, 48, 72, and 96 h of exposure. The impedance spectra of the corrosion monitoring of AISI 304 stainless steel differs from both AISI 430 stainless steel and nickel-based alloy HR-224. AISI 304 stainless steel shows similar behavior up to 48 h of measurement in contrast to 72 and 96 h, where a small increase of the high frequency semi-circle can be seen due to the load transfer reaction at the metal/molten interface. In the cases of stainless steel AISI 430 and the nickel-based alloy HR-224, they show a consistent formation in their high and low frequency semi-circles, indicating the charge transfer reaction and the corrosion resistance of the protective layer respectively. The difference in the behavior of the impedance spectra in both the solar salt and the ternary mixture may be due to the LiNO\({}_{3}\) content; as it is more basic than KNO\({}_{3}\) and NaNO\({}_{3}\), it has a high activity in the ternary mixture (KLiNa)NO\({}_{3}\). According to [PERSON] et al. [10], the formation of various compound oxides is evidenced by the effect of lithium diffusion in the metal, which generates a series of surface layers apart from the protective layer at the metal/molten interface. Thus, the impedance spectra of these materials show a similar fit to a non-active metal model of the protective layer. This can be explained by the sufficiently high chemical stability in the molten salt systems, in the case of HR-224 and AISI430 materials. The results obtained in terms of the equivalent electrical circuits obtained from the spectra shown in (LiNaK)NO\({}_{3}\), are represented in the Tables 6-8. Figure 11: Nysquist diagram of stainless steel 430 layer in (LiNaK)NO\({}_{3}\) (ternary salt with lithium content) at 2 h, 4 h, 24 h, 48 h, 72 h, 96 h at 550 \({}^{\circ}\)C. \begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Time** & \(R_{s}\) & \(C_{dl}\) & \(\beta_{dl}\) & \(R_{t}\) & \(C_{ox}\) & \(\beta_{ox}\) & \(R_{ox}\) \\ \hline  & \(\Omega\)**-cm\({}^{2}\)** & **F s\({}^{(\beta}\)d\({}^{-1}\)b** & & \(\Omega\)**-cm\({}^{2}\)** & **F s\({}^{(\beta}\)d\({}^{-1}\)b** & & \(\Omega\)**-cm\({}^{2}\)** \\
2 h & 2.047 & 0.140 & 0.625 & 52.00 & 0.012 & 0.62 & 10.00 \\
4 h & 2.049 & 0.142 & 0.692 & 42.94 & 0.013 & 0.62 & 10.23 \\
24 h & 2.098 & 0.020 & 0.560 & 9.70 & 0.150 & 0.68 & 50.00 \\
48 h & 2.221 & 0.025 & 0.530 & 10.10 & 0.190 & 0.71 & 47.56 \\
72 h & 2.194 & 0.041 & 0.480 & 12.35 & 0.230 & 0.77 & 46.87 \\
96 h & 2.074 & 0.062 & 0.410 & 22.78 & 0.430 & 0.91 & 28.36 \\ \hline \end{tabular}
\end{table} 
Table 7: Fitting results of the impedance spectra of stainless steel 430 during corrosion in the presence of (LiNaK)NO\({}_{3}\) (ternary salt with lithium content) at 550 \({}^{\circ}\)C. \begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Time** & \(R_{s}\) & \(C_{dl}\) & \(\beta_{dl}\) & \(R_{t}\) & \(C_{ox}\) & \(\beta_{ox}\) & \(R_{ox}\) \\ \hline  & \(\Omega\)**-cm\({}^{2}\)** & **F s\({}^{(\beta}\)d\({}^{-1}\)b** & & \(\Omega\)**-cm\({}^{2}\)** & **F s\({}^{(\beta}\)d\({}^{-1}\)b** & & \(\Omega\)**-cm\({}^{2}\)** \\
2 h & 2.047 & 0.140 & 0.625 & 52.00 & 0.012 & 0.62 & 10.00 \\
4 h & 2.049 & 0.142 & 0.692 & 42.94 & 0.013 & 0.62 & 10.23 \\
24 h & 2.098 & 0.020 & 0.560 & 9.70 & 0.150 & 0.68 & 50.00 \\
48 h & 2.221 & 0.025 & 0.530 & 10.10 & 0.190 & 0.71 & 47.56 \\
72 h & 2.194 & 0.041 & 0.480 & 12.35 & 0.230 & 0.77 & 46.87 \\
96 h & 2.074 & 0.062 & 0.410 & 22.78 & 0.430 & 0.91 & 28.36 \\ \hline \end{tabular}
\end{table}