Developing Corrosion Inhibitors – Using SEM to Investigate Corrosion

Inhibiting corrosion in metals would be beneficial in a large number of industries. In the materials science domain, Researchers are therefore seeking ways to reduce or prevent corrosion. Many studies have been carried out in search for suitable corrosion inhibitors.

Yet, a majority of the inhibitors discovered and designed during those studies were synthetic chemicals, which are not only expensive but are also dangerous to the environment. Due to the characteristics of these chemicals, studies were performed to explore and analyze natural products that could be employed as an anti-corrosion agent. Using scanning electron microscopy (SEM), these studies were carried out in an effective manner. This article describes further how such studies have been effectively carried out using SEM.

The Use of Castor Oil Extract to Inhibit Corrosion

In 2017, Omotioma et al. (Int. J. Chem. Sci.: 14(1)) explain the use of castor oil (Ricinus communis) extract for inhibiting corrosion in mild steel. In this study, SEM was used to perform morphological observations of the corroded mild steel samples. The study results revealed that castor oil extract could inhibit both anodic and cathodic reactions and act as a mixed-type inhibitor.

In 2015, the same research group (Der Pharma Chemica, 2015, 7 (11):373-383) studied the use of leaves extract of bitter leaf (Vernonia amygdalina) as a corrosion inhibitor for aluminum. Here, the use of a SEM helped revealing the detailed changes in morphology and served as a useful tool to gain insights into morphological changes in detail.

Corrosion Behavior on Stainless Steel

In 2016, Loto (J Mater Res Technol. 2016) carried out a comprehensive study on corrosion behavior of stainless steel, with a special focus on oil refinery distillation systems. During this study, SEM was used to analyze the surface morphology in detail to identify surface changes or defects. The ability to understand surface morphology along with elemental detection through EDS allows results to be obtained in a rapid and easy manner. The study successfully proved that the corrosion rates of S32101 steel are significantly lower than that of 410 martensitic stainless steel employed for applications in oil refinery distillation systems.

Figure 1. SEM image of speed steel.

Figure 2. SEM image of aluminum.

This information has been sourced, reviewed and adapted from materials provided by Phenom-World BV.

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