## 3 Results and Discussion
### Morphology Evaluation
The successful generation of a layer with cracks is probably due to the drying process, implying the conjunction of the organic inhibitor molecule (MBT) to a mild steel surface, as well as the formation of tertiary phosphates [26; 60] (Figure 6c,d). The EDS analysis of Figure 6c reveals elevated oxygen value concentrations compared to that of the sample _Steel-blank_ due to the creation of the aforementioned iron oxides along with the presence of sulfur and phosphorus elements that are attributed to the adsorbed organic MBT and inorganic phosphates, respectively (Table 3). The surface SEM images of mild steel subjected to 3.5 wt % NaCl (_Steel-NaCl-blank_) for 96 h are illustrated in Figure 5:0 It can be seen that there is a surface distinctly damaged by the saline solution, with the characteristic appearance of an etched layer near the metal surface, as chloride anions accelerate corrosion phenomena (Figure 7a,b). In several areas, bigger bulk crystalline tubular or rod-like forms of goethite (often visually yellowish to reddish rust) or hematite (visually metallic gray rust) [54; 61] and distinguishable cloud-like [3] leptodecrocite crystals are depicted (Figure 7c,e). As commented in preceding studies, it seems that small amounts of goethite were formed after a significant exposure time [3] by lepidocrocite solid transformation due to the presence of chloride ions as well as by the transformation of green rust (FeII\({}_{\text{x}}\)FeVIII(OH)3x+2y-z(A^{-})_{\text{z}}\)[54]) during the drying process (Figure 7d,e). The chloride ions, as aggressive anions, are considered [49] to accelerate the corrosion process, penetrating the protective layer and hence attacking the fresh unharmed metal surface beneath the layer, triggering pitting corrosion. Therefore, chloride anions may not be detected onto the corrosion product layer neither as ferrous (FeCl\({}_{2}\)) nor as ferric (FeCl\({}_{3}\)) salts, which are initially formed [47; 62], since these salts are meant to be significantly soluble in water. The EDS analysis of Figure 7e reveals an elevated oxygen value concentration compared to that of the _Steel-blank_ sample due to the formation of the previously mentioned iron oxides (Table 3). The surface SEM images of _Steel-NaCl-Na2 HPO\({}_{4}\)_ after exposure in 3.5 wt % NaCl for 96 h are depicted in Figure 5:1 It seems that globular axially generated spongy agglomerations have constructed a quite homogenous voluminous layer, currently hindering the exposure of the inner layer on the metal surface. As mentioned before, these agglomerations are attributed to lepidocrocite, maghemite, and precursors of green rust (as magnetite) created in NaCl solution [15] and are not yet removed, due to the prolonged exposure process [3; 63] (Figure 8a,b). Furthermore, miscellaneous laminas accreting in thorny three-dimensional structures [3] resemble hematite and goethite (sharper, more acicular) \(\alpha\) phases with small aggregates of more globular lepidocrocite (or/and maghemite), which are precipitated during the submission together with tertiary phosphates [46; 60; 64] (Figure 8c,d). As mentioned before, cracks with diameters of a few micrometers are considered to be due to the drying stage (Figure 8b). The EDS analysis of Figure 8b,d reveals elevated oxygen value concentrations compare to that of the sample _Steel-blank_ due to the formation of the aforementioned iron oxides as well as the presence of phosphorus, which is assigned to the adsorbed phosphates (Table 3). The surface SEM images of mild steel immersed in 3.5 wt % NaCl for 96 h in the presence of MBT (_Steel-NaCl-MBT_) are demonstrated in Figure 5:2 Characteristic laminar and eroded rosettes of green rust, lepidocrocite, and hematite consist of the three-dimensional structures (Figure 9a), while the ruptured inner layer (Figure 9c) indicates the inhibitor (MBT) interaction with the steel surface [29; 64; 65].