*3.3. Salt Spray Corrosion Tests*

The results of the weight loss of the steel specimens (bare and covered with pristine epoxy and nanocomposites) upon salt spray exposures are summarized in Figure 6. Optical images of the specimens are shown in Figure 7, while representative scanning electron (SEM) images of the bare and coated specimens are shown in Figure 8.

From the weight loss results (Figure 6) it can be seen that after 1 day of exposure the weight loss of bare steel was about 0.16 wt % and was raised to 1 wt % after 4 days. The neat epoxy polymer showed a relatively good protection efficiency by reducing the weight loss, at 0.07 wt % and 0.4 wt % for the first and fourth day, respectively. A greater improvement in protection was offered by both the epoxy nanocomposites (with I.28E and I.30E organoclays) which inhibited the weight loss, exhibiting similar very low values of ca. 0.03–0.04 wt % and 0.15–0.18 wt % after 1 and 4 days of exposure. These latter values correspond to 75% and 80–90% less weight loss, after 1 and 4 days of exposure, by the use of the epoxy nanocomposites compared to the pristine steel specimens. The differences in corrosion between the bare steel specimen and those covered by the thin epoxy polymer or the epoxy nanocomposites, can be also clearly observed in the respective optical photographs, after 1 and 4 days of exposure, as shown in Figure 7. From these images it follows that the corrosion of coated specimens, especially I.28 and I.30 coated steel—Figure 7c,d, after 1 or 4 days of exposure, is less intense than the corresponding bare steel specimens. The SEM images of the various specimens before the salt spray test (no exposure) and after 1 or 4 days of exposure are shown in Figure 8. In the same figure the cross-section image of I.30 coated steel is shown. In these images the differences in the initial morphology and the corrosion behaviour of the bare and coated steels as well as the coating thickness and the coating-steel interface can be observed.

**Figure 6.** Weight loss results from salt spray experiments for bare steel and steel coated with pristine epoxy resin, and nanocomposites with I.28 and I.30 organo-clays, after 1 day (**a**) and 4 days (**b**) of exposure in a corrosive environment of 100% saturated moisture + 5 wt % NaCl solution.

**Figure 7.** Salt spray corrosion test samples after 1 day (**A**) and 4 days (**B**) of exposure in a corrosive environment of 100% saturated moisture + 5 wt % NaCl solution: (a) bare steel; (b) coated with pristine resin; (c) coated with I.28E nanocomposite; (d) coated with I.30E nanocomposite.

(**A**) No exposure

(**B**) Cross section

**Figure 8.** *Cont.*

(**D**) 4 days

**Figure 8.** Scanning electron micrographs of initial (no exposure) (**A**), cross section of steel coated with I.30E (**B**), and salt spray tested specimens after 1 day (**C**) and 4 days (**D**) of exposure in a corrosive environment of 100% saturated moisture + 5 wt % NaCl solution: (a) bare steel; (b) coated with pristine resin; (c) coated with I.28E nanocomposite; (d) coated with I.30E nanocomposite.
