How SEM helps discover suitable corrosion inhibitors

By Karl Kersten - June 12, 2017

Many industries would benefit from the inhibition of corrosion in metals. In the materials science field, scientists are therefore exploring ways to prevent or reduce corrosion. Many studies looking for suitable corrosion inhibitors have been carried out.

However, most of the inhibitors discovered and developed during those studies were synthetic chemicals, which are very expensive, and hazardous to the environment. Due to the characteristics of these chemicals, studies were carried out to investigate and analyze natural products that could be used as an anti-corrosion agent. SEM technology helped conduct these studies in an effective manner, something we will describe further in this article.

The use of castor oil extract to inhibit corrosion

In 2017 Omotioma et al. (Int. J. Chem. Sci.: 14(1)) describe the use of castor oil (Ricinus communis) extract to inhibit corrosion of mild steel. Morphological observations of the corroded mild steel samples were carried out using scanning electron microscopy (SEM). As a result of this study, castor oil extract was found to inhibit both cathodic and anodic reactions and act as a mixed-type inhibitor.

Another study from the same research group in 2015 (Der Pharma Chemica, 2015, 7 (11):373-383) investigated the use of leaves extract of bitter leaf (Vernonia amygdalina) as corrosion inhibitor for aluminum. In this case, detailed changes in morphology were also revealed with the use of a SEM, which serves as a helpful tool to understand morphological changes in detail.

Corrosion behavior on stainless steel

A more detailed study on corrosion behavior on stainless steel, with a focus on oil refinery distillation systems, was performed by Loto in 2016 (J Mater Res Technol. 2016). During this study, the surface morphology was analyzed in more detail with SEM to detect defects or surface changes. The capability to understand surface morphology in combination with elemental detection via EDS allows results to be obtained in a fast and easy manner. The study was successful in proving that S32101 steel has significantly lower corrosion rates than 410 martensitic stainless steel used for applications in oil refinery distillation systems.

speedsteel0014.jpg Al2O3-C blog week 23.jpg

Fig. 1: SEM image of speed steel                             Fig. 2: SEM image of aluminum

If you would like to learn more about the potential of a SEM system paired with EDS technology, you can download the Phenom ProX specification sheet here:

ProX specification sheet

About the author

Karl Kersten is head of the Thermo Scientific Phenom Desktop SEM Application Team at Thermo Fisher Scientific. He is passionate about the Phenom Desktop SEM product and likes converting customer requirements into product or feature specifications so customers can achieve their goals.

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