## 3 Results and Discussion
### Morphology Evaluation
It should be taken  
Figure 10: SEM images of mild steel immersed in 3.5 wt % NaCl for 96 h in the presence of Na\({}_{2}\)HPO\({}_{4}\) + MBT. into account that the special influence of phosphate anion is participating in various chemical paths. Although adsorbed phosphate is assumed to act as a precursor for hematite creation and often for goethite nucleation and growth, at different concentrations and especially at locally more basic areas, phosphate anions increase the negative electronic charge of ferrihydrite (present at earlier stages) between particles. Therefore, the formation of hematite retards or is limited [44]. Since the samples have undergone primary aging, in conjunction with the spectroscopic measurement results, it is considered that a part of the magnetite layer has decomposed in a binary solid-state transformation. At the same time, a structural conversion of magnetite, oxidizing partially to form maghemite and a compositional frontal transformation to hematite take place [55]. The choice of the physicochemical path that will be followed depends primarily on the anion concentration [56; 57]. The EDS analysis of Figure 4b,f 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 that is assigned to the adsorbed phosphates (Table 3). Figure 5 pictures the surface SEM images of mild steel submitted to WSS for 96 h in the presence of MBT (_Steel-WSS-MBT_). It can be seen that hexagonal double-plates are illustrated, revealing the presence of magnetite [58], the precipitation of Fe\({}^{2+}\) and Fe\({}^{3+}\) ions from the solution, and the creation of green rust particles (general type [Fe\({}^{2+}\)(1-x)Fe\({}^{3+}\)\(\times\)(OH)\({}_{2}\)]\({}^{x+}\)) (Figure 5a,b). Positively charged ions from corroded iron forms sediments of double-hydroxide layers, consisting of coordinated Fe\({}^{2+}\) and Fe\({}^{3+}\) octahedra with hydroxylate groups between them [48; 59]. Green rust acts as an ion exchange surface withholding other species of metal ions and decreasing locally the negative charge between the particles of the corrosion products, conferring more stability to the final layer [54; 59]. Moreover, unattached geode type formations are present, enhancing the assumption of magnetite creation with smaller crystals of lepidocrocite inside the cavity, as the former is mostly detected near the metallic surface as a blackish oxide [58], while the latter usually constitutes the biggest part of the total corrosion products above (Figure 5c,d). Additionally, the creation of primarily small amounts of akaganeite [\(\beta\)-FeO(OH)] is considered, whereas the precise identification of these phases was complicated using the SEM technique [46; 47]. Taking into account the capture of cracks (Figure 5e,f), it may be remarked that a quite thick and compact inner layer was generated from the inhibitor (MBT) adsorption [29], in parallel with the conventional corrosion products of the mild steel, such as crystals of lepidocrocite and other aforementioned bulk structures of goethite, maghemite and lepidocrocite. The EDS analysis of Figure 5e,f discloses elevated oxygen value concentrations compared to that of the _Steel-blank_ sample due to the formation of the aforementioned iron oxides as well as the presence of sulfur that is ascribed to the adsorbed organic MBT (Table 3). The surface SEM images of mild steel immersed in WSS for 96 h in the presence of MBT together with Na\({}_{2}\)HPO\({}_{4}\) (_Steel-WSS-Na\({}_{2}\)HPO\({}_{4}\)-MBT_) are demonstrated in Figure 6. Bulky corrosion products as tubular rods are predicting the creation of \(\alpha\) and \(\beta\) phases of iron oxides, as well as more fine-grained phases of the expended corroded phases, as the interactivity of the mild steel with the inhibitors lessened the rate and the extent of the corrosion process (Figure 6a,b).