## 3 Results and Discussion  
Figure 1 shows the linear polarization-resistance curves for solutions saturated by CO\({}_{2}\). Figure 2 shows the curves for the reading of the linear polarization resistance. Table 1 shows the measured and calculated values for the different mediums. Siderite (FeCO\({}_{3}\)) is an isostructural mineral in calcite (CaCO\({}_{3}\)) and magnesite (MgCO\({}_{3}\)) regarding the cell parameters (as they crystallize in the same crystal system and the atoms in the unit cell are in the same positions). The specific defects of these isostructural minerals are vacancies and stacking faults, among others [24]. On the other hand, dolomite [CaMg(CO\({}_{3}\))\({}_{2}\)] also has a crystal structure similar to calcite; however, it exhibits alternate rows of Ca and Mg ions along [421] the surface (10\(\overline{4}\)). These have been dealt with in studies [25; 26] with atomic force microscopy (AFM) applied to calcite, dolomite, and magnetic surfaces in water, through a large-scale atomic/molecular massively parallel simulator (LAMMPS) MD code and free-energy calculations. It was found that water exchange on Ca for dolomite slowed down in a magnitude-order different from calcite. This indicates that a dolomite layer on the steel surface is more protective than a calcite layer, because the latter dissolves faster in an aqueous medium. Due to the structural similarity between dolomite and ankerite [CaFe(CO\({}_{3}\))\({}_{2}\)] [27; 28], which are almost identical, we can infer from the corrosion point of view that an ankerite layer formed on the steel surface is more protective  
Figure 1: Linear polarization-resistance test, 600 rpm, 65 \({}^{\circ}\)C, potentials vs. Ag/AgCl. than a calcite and/or siderite layer, since the former two are isostructural. This conjecture is verified in Table 1, assay 10, where CR is the lowest at 0.97 mmpy due to anexite formation. In these assays, carbon steel is in contact with CO\({}_{2}\) and CaCO\({}_{3}\), Fe (II) slows down calcite growth by blocking the growth sites and incorporating into CaCO\({}_{3}\)[29; 30; 31; 32]. [PERSON] et al. [2], using synthetic seawater at 60 \({}^{\circ}\)C and 1 atm of CO\({}_{2}\), found depositions on a carbon steel surface, such as FeCO\({}_{3}\), CaCO\({}_{3}\), and \(\alpha\), \(\gamma\)\(\bullet\) Fe\({}_{2}\)O\({}_{3}\)\(\bullet\) H\({}_{2}\)O, which were identified using X-ray diffraction analysis. On the other hand, [PERSON] [33] assumed FeO\({}_{3}\) to be an n-type semiconductor with a transport mechanism \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \multirow{2}{*}{**Sample**} & **NaCl** & **CaCO\({}_{3}\)** & **CaCl\({}_{2}\)** & **Na\({}_{2}\)CO\({}_{3}\)** & **pH** & **Rp [\(\Omega\)]** & **Ecorr** & **i** & **[mV]** & **[μA/cm\({}^{2}\)]** & **CR [mmpy]** \\  & **[ppm]** & **[ppm]** & **[ppm]** & **[ppm]** & **[ppm]** & **[ppm]** & **[μA/cm\({}^{2}\)]** & **[μA/cm\({}^{2}\)]** & **[μA/cm\({}^{2}\)]** & **[μA/cm\({}^{2}\)]** & **[μA/cm\({}^{2}\)]** \\ \hline
1 & 20,000 & - & 1380 & - & 4.07 & 23 & \(-\)704 & 463 & 5.38 & \\ \hline
2 & 20,000 & - & - & - & 4.38 & 25 & \(-\)686 & 431 & 5.01 & \\ \hline
3 & 20,000 & - & - & 1360 & 6.74 & 28 & \(-\)712 & 379 & 4.41 & \\ \hline
4 & 20,000 & 1250 & - & - & 5.71 & 31 & \(-\)719 & 349 & 4.06 & \\ \hline
5 & 1450 & - & - & - & 4.04 & 47 & \(-\)644 & 223 & 2.59 & \\ \hline
6 & - & - & 1380 & - & 4.03 & 53 & \(-\)703 & 201 & 2.34 & \\ \hline
7 & - & - & - & 1360 & 6.75 & 68 & \(-\)712 & 156 & 1.81 & \\ \hline
8 & - & - & 500 & - & 4.12 & 87 & \(-\)611 & 121 & 1.41 & \\ \hline
9 & - & - & - & 424 & 6.34 & 98 & \(-\)678 & 101 & 1.29 & \\ \hline
10 & - & 1250 & - & - & 5.97 & 126 & \(-\)715 & 84 & 0.97 & \\ \hline \end{tabular}
\end{table} 
Table 1: Measurements vs. Ag/AgCl and calculations at 65 \({}^{\circ}\)C, 600 rpm, and saturated CO\({}_{2}\). Figure 2: Graph for the linear polarization-resistance calculations. tials, thus explaining the CO\({}_{2}\) corrosion mechanism for AISI 1018.