Effects of Ag nanoparticles electrodeposited on oxy-nitrocarburized AISI 304 SS into the corrosive and antibacterial activity

Abstract

The service life of materials in aggressive environments, such as seawater, is of paramount importance due to the significant risks of mechanical failure and the associated economic costs. Consequently, ongoing research focuses on enhancing materials to withstand corrosion, wear, and microbiological degradation. This study investigates the effects of silver nanoparticles (AgNPs) electrodeposited on an oxy-nitrocarburized AISI 304 stainless steel (SS) substrate. Microstructural and chemical characterizations were performed using X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), and X-ray Photoelectron Spectroscopy (XPS). Additionally, wettability, electrochemical corrosion resistance, and bacterial inhibition tests were conducted using the Gram-negative bacterium Escherichia coli to assess the antibacterial activity of the AgNPs. These findings indicate that the initial AgNP layer fails to enhance corrosion resistance, likely due to insufficient surface coverage or weak interfacial bonding. This phenomenon is consistent with the formation of a galvanic couple, wherein the electrochemical potential difference between silver (+0.80 V) and stainless steel (Fe: -0.14 V) promotes electron transfer from the less noble substrate to the AgNPs, thereby accelerating the anodic dissolution of the steel surface. Furthermore, the contact angle was identified as a critical factor influencing both antimicrobial performance and corrosion resistance. All AgNP-modified surfaces exhibited exceptional antibacterial activity, exceeding 99 % inhibition efficiency. This study highlights the potential of oxy-nitrocarburization as a robust surface modification technique for facilitating the nucleation and growth of nanoparticles, paving the way for advanced coatings capable of addressing the multifaceted challenges of material degradation in corrosive seawater environments.