Electrochemical polishing versus mechanical polishing of AISI 304: surface and electrochemical study

• Published in: Journal of solid state electrochemistry Vol. 26; no. 1; pp. 121 - 129
• Main Authors: Abouelata, Ahmed M. Awad, Attia, Adel, Youssef, Gehan I.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 2022; Springer Nature B.V
• Subjects: Aerospace industry; Analytical Chemistry; Atomic force microscopy; Brightening; Characterization and Evaluation of Materials; Chemical polishing; Chemistry; Chemistry and Materials Science; Condensed Matter Physics; Corrosion; Corrosion rate; Corrosion resistance; Density; Electrochemical impedance spectroscopy; Electrochemistry; Electrode polarization; Electropolishing; Energy dispersive X ray analysis; Energy Storage; Gloss; Manganese; Mechanical polishing; Microscopy; Original Paper; Physical Chemistry; Smoothness; Surface properties; X ray analysis; Mott-Schottky analysis; Mechanical polishing; Stainless steel; Roughness; electrochemical polishing; Potentiodynamic polarization; Impedance spectroscopy
• ISSN: 1432-8488; 1433-0768
• DOI: 10.1007/s10008-021-05037-2

AISI 304 is essential for vital industries, e.g., aerospace, nuclear plants, pharmaceutical, chemical, and medical industries. Enhancement of AISI 304 surface characteristics is required for protection, durability, and better performance. Different methods were used for surface modification like mechanical polishing (MP) and electrochemical polishing (EP). Scanning electron microscopy, atomic force microscopy, and gloss values revealed the alleviation of humps, imperfection and roughness, and leveling. Smoothness and brightening of the surface after EP (∆ R  = − 1.206 nm) was more than that of MP treatment (∆ R  = − 0.562 nm). Energy dispersive X-ray analysis showed increase of Cr, Ni, and Mn content while the content of Fe decreased after EP treatment. Potentiodynamic polarization of EP AISI 304 in 3.5% NaCl revealed a high polarization resistance ( R p  = 2786 kΩ) and low corrosion rate of 2.74 × 10 −5  mm year −1 ). These parameters were compared to that of MP AISI 304 of lower polarization resistance ( R p  = 168 kΩ) and higher corrosion rate of 6.01 × 10 −5  mm year −1 ). Potentiodynamic polarization shows that the E corr was −61.09 mV for EP samples compared to −127 mV for MP samples and that the corrosion rate for MP samples was higher than that of EP samples. Mott-Schottky analysis shows a donor densities of 1.370 × 10 22  cm −3 for the EP samples vs. 3.014 × 10 21  cm −3 for MP samples, while acceptor densities of 8.304 × 10 21  cm −3 for EP samples vs. 7.389 × 10 22  cm −3 for MP samples compared to unpolished sample of donor density of 2.036 × 10 21  cm −3 and acceptor density of 8.784 × 10 20  cm −3 which evidenced the better performance for EP treatment. The results were supported by electrochemical impedance spectroscopy as well.