Effects of electrochemical techniques on carbon steel in agar

Electrochemical corrosion techniques are traditionally employed to study corrosion in soil in the laboratory, with solution as the electrolyte. However, the physical structure of soil has been shown to be essential to corrosion in soil, which is not represented with liquid solution. This is important when studying microbiologically influenced corrosion (MIC) as the physical structure affects bacteria movement in soil. Therefore, a semi-solid agar system has been developed to provide the physical structure of soil for studying soil corrosion in the laboratory. Although correlations have been previously drawn between the agar system and clay-based soil, this work aims to further validate the soil analogue system through investigation of the physical properties of agar and of several the key parameters of corrosion in soil using electrochemical corrosion techniques. Dissolved oxygen concentration of the semi-solid agar system is varied, with specific responses observed under different conditions using potentiodynamic polarisation scanning (PDS) and microscopy techniques including scanning electron microscopy (SEM) to compare with corrosion in solution. Although limited in scope, these results provide insights into how metals, particularly carbon steel, respond to applied potentials from electrochemical techniques under different agar conditions, which will form the basis of ongoing research into characterising the semi-solid agar system as a potential analogue of soil.