Eco-friendly electrochemical polishing of stainless steel using a NaCl-based electrolyte to reduce deterioration in seawater

Abstract

One of the most significant technological challenges in implementing ocean energy conversion systems is ensuring the reliability and extending the service life of their components. Stainless steel has found widespread use in marine applications; however, it is susceptible to localized corrosion, erosion, and biocorrosion when exposed to seawater. In response to these challenges, selective electrodissolution has emerged as a promising strategy. Typically, the standard electrodissolution procedure is performed with acid-based electrolytes, generating environmental and safety problems. In this research, green electrolytes composed of ethylene glycol, sodium chloride, and water were used to selectively modify the surface of AISI 304 SS. Electrochemical behavior, wettability properties, surface characteristics, and corrosion resistance in simulated seawater were evaluated using cyclic voltammetry, contact angle, scanning electron microscopy and cyclic potentiodynamic polarization techniques, respectively. The anodic dissolution tests and their corresponding analysis indicated that the best surface modification was achieved by a potential of 4.0 V, a treatment time of 30 min, and an electrolyte of 10 wt. % NaCl, 67 wt. % EG and 23 wt. % H₂O. Under these conditions, a hydrophobic surface was obtained, with a 72.2 % increase in resistance to pitting corrosion and a 71.8 % reduction in the general corrosion rate compared to untreated AISI 304. The incorporation of H₂O into the EG solvent enhanced the selectivity of its electrodissolution process, reducing energy consumption and operational costs while increasing the environmental friendliness of the electrolyte.