Insight into the synergetic effect of alanine-derived copolymer and KI on the corrosion inhibition of SLM manufactured 17-4 PH steel in acidified NaCl solution

The 17 − 4 precipitation hardening (PH) stainless steel, produced by additive manufacturing (AM), provides an exceptional balance of strength, toughness, and corrosion resistance, making it a versatile engineering alloy, especially in the aerospace sector. Nonetheless, microstructural defects that occur during manufacturing adversely affect its application in structural contexts, particularly concerning corrosion issues. In the current study, a novel Alanine-derived water-soluble copolymer referred to as L-1 was synthesized, characterized and its ability to suppress corrosion of SLM printed 17 − 4 PH steel in an acidified NaCl solution is examined. Electrochemical and surface characterizations and computational methods were systematically utilized to explore individual inhibitors' inhibitory efficacy and synergistic effects and their blends with potassium iodide (KI). Based on the electrochemical outcomes, the synergistic mixture of L-1/KI (hybrid inhibitor) gave an impressive rate of corrosion inhibition efficiency than that of individual and blank ones. An index of synergism greater than one showcases a more significant potential for passivation (hybrid inhibitor) in mitigating corrosion progression. The adsorption or chelation of an inhibitive co-polymer film on the metal surface was examined utilizing X-ray photoelectron spectroscopy (XPS), FT-IR, and UV vis analyses. An examination of surface morphology using SEM and AFM revealed a smooth surface, devoid of conspicuous corrosion features in the presence of the co-polymer, more prominent with the blend. Quantum chemical (QC) calculations and Mulliken charge analysis indicate that active centers for the heightened corrosion inhibitory efficiency are predominantly located on benzene rings and alanine pendant groups. The combined experimental-theoretical approach highlights the effectiveness of hybrid water-soluble copolymer inhibitors as novel and efficient corrosion inhibitors within the realm of sustainable chemistry.