# Recent Trends and Progress in Corrosion Inhibitors and Electrochemical Evaluation
## 5 Corrosion Monitoring Techniques
### Tafel Polarization Techniques  
To study the kinetics and processes of corrosion reactions, Tafel polarization studies are a common technique in the fields of corrosion research and electrochemistry. These investigations shed important light on the rate of corrosion, the propensity for corrosion, and the behavior of different materials in corrosive environments. A material exposed to a corrosive environment can benefit from having its corrosion rate, propensity for corrosion, and other electrochemical properties described. The Tafel equations, which link an electrode's current density to the applied potential, serve as the foundation for this approach. Researchers and engineers can precisely calculate the corrosion rate of a metal using the Tafel polarization method. A polarization curve (Tafel plot) can be produced by measuring the current density at various applied potentials. The rate of corrosion is determined by the slope of this curve at the corrosion potential. A steeper slope denotes a faster rate of deterioration [163].  
Ferritic steel's corrosion behavior was examined by [PERSON] et al. [164] under conditions similar to those seen in oil fields. Separate Tafel polarization measurements were used to verify the correctness of the results. Through the use of weight loss and Tafel polarization techniques, [PERSON] et al. [165] examined the corrosion inhibition of MS by 7- (ethylthiophenzimidazolyl) theophylline (7-ETBT) in 1 M HCl medium between the temperatures of 298 and 318 K. By combining a self-powered cathodic protection based on a triboelectric nanogenerator (TENG) and a green corrosion inhibitor of zinc gluconate (ZnG), [PERSON] et al. [166] developed an anticorrosion system. Using Tafel polarization curves, they assessed the performance of the synergetic anti corrosion system. [PERSON] et al. [167] extracted Garcinia livingstonei leaves and used them as a green CI in 1 M HCl medium;  
Figure 20: SECM 3D pictures of (**a**) blank steel and (**b**) steel with GG–AMPS coating submerged in synthetic saltwater [158].  
the inhibition effect was studied by employing Tafel polarization methods. By using Tafel polarization techniques at room temperature, [PERSON] et al. [168] examined the corrosion inhibition and adsorption behavior of spermidine on MS in 1 M sulfuric and 0.50 M hydrochloric acid. The Tafel plots of MS in HCl and H2 SO4 with and without spermidine are shown in Figure 21. Anodic Tafel slope (a), cathodic Tafel slope (c), corrosion potential (Ecorr), corrosion current (Icorr), and polarization resistance (Rp) were all deduced from the Tafel plots. After adding spermidine to the electrolytes, the corrosion current decreases. Additionally, the corrosion current value drops as inhibitor concentration rises, suggesting that the inhibitor forms a non-conductive layer on the MS surface and reduces the corrosion current while enhancing the IE. Additionally, no structural changes were seen in the anodic and cathodic branch Tafel plots when spermidine was present, indicating that the inhibitor had no effect on the corrosion mechanism.