**4.4.3 Inhibited specimen with NH**

Figure 9 depicts the SEM of the specimen surface after 60 days of immersion in seawater with the addition of 1000 ppm of NH. It can be seen that the flakes in the surface of the specimens decreased as compared to that of the micrograph in Figure 8. The specimen is covered with the inhibitor molecules giving a protection against corrosion, where a thin layer developed on the specimen surfaces.

Fig. 9. SEM of specimen surface after immersion in seawater containing 1000 ppm of NH.

The EDS spectrum in Figure 8 presents the elements exist in Al-Mg-Si alloy after immersion test. It shows the presence of sodium (Na) and chlorine (Cl) in the specimen surface. Seawater predominantly consists about 3.5% of sodium chloride (NaCl) and many other ions. Chloride ions are very strong, and could easily penetrate the passive film, and

dissolution of the aluminium substrate occurs and results in corrosion.

Fig. 8. EDS analysis of Al-Mg-Si alloy surface after 60 days of immersion.

Figure 9 depicts the SEM of the specimen surface after 60 days of immersion in seawater with the addition of 1000 ppm of NH. It can be seen that the flakes in the surface of the specimens decreased as compared to that of the micrograph in Figure 8. The specimen is covered with the inhibitor molecules giving a protection against corrosion, where a thin

Fig. 9. SEM of specimen surface after immersion in seawater containing 1000 ppm of NH.

**4.4.3 Inhibited specimen with NH** 

layer developed on the specimen surfaces.

The EDS spectrum in Figure 10 shows the existence of carbon (C), oxygen (O) and sulphur (S); due to the carbon, oxygen and sulphur atoms of the NH. These data show that carbonaceous material containing O and S atoms has covered the specimen surface. This layer is absolutely due to the inhibitor, because the carbon signal and the high contribution of the oxygen signal are absent on the specimen surface exposed to uninhibited seawater. It can be seen obviously from the spectra, the Al peaks are dramatically suppressed relative to the samples in uninhibited seawater (Figure 8). This is due to the overlying inhibitor film on the specimen surface area (Amin *et al*., 2009).

Fig. 10. EDS analysis of Al-Mg-Si alloy immersed in seawater containing 1000 ppm of NH.
