Electrochemical Evaluation of Corrosion Inhibitors on the Corrosion Behavior of 13CrMo44 Steel in NH 4 Cl Solution

This work systematically examines how different corrosion inhibitors and their concentrations influence the corrosion behavior of 13CrMo44 steel in NH 4 Cl solution using electrochemical techniques combined with surface morphology characterization. The results demonstrate that all tested inhibitors effectively suppress corrosion, as evidenced by reduced corrosion current density, increased charge-transfer resistance, and improved surface integrity. Inorganic inhibitors exhibit a broad effective concentration range, with their performance remaining relatively insensitive to dosage variations once a stable protective film is formed. In contrast, organic inhibitors show a pronounced concentration-dependent response. For example, sodium dodecyl sulfonate (SDS2) displays a distinct optimal concentration at 0.05 g/L, beyond which excessive interfacial adsorption disrupts film compactness and diminishes inhibition efficiency. These findings highlight that optimal inhibitor performance depends strongly on molecular structure and precise concentration control. The study provides both theoretical insight and practical guidance for selecting and optimizing corrosion inhibitors for 13CrMo44 steel in ammonium chloride environments.