Nano-Zeolite-Mediated Silver Dispersion in Alkoxysilane Resin Coatings for Suppression of Biofilm-Accelerated Corrosion in Marine Environments

Prof. Hideyuki Kanematsu , The University of Osaka, Suita, Japan, BEL Inc., Sakai, Osaka, Japan
Prof. Akiko Ogawa , National Institute of Technology, Suzuka College, Suzuka, Japan
Dr. Michiko Yoshitake , Nagoya University, Nagoya, Aichi, Japan
Prof. Takeshi Bessho , Nagoya University, Nagoya, Aichi, Japan
Prof. Ryoichi Ichino , Nagoya University, Nagoya, Aichi, Japan
Prof. Takayoshi Nakano , Graduate School of Engineering, The University of Osaka, Suita, Osaka, Japan
Biofouling in marine environments proceeds through a well-established sequence: initial microbial adhesion, biofilm maturation, and subsequent macrofouling by organisms such as barnacles and oysters. Biofilm formation on metallic substrates also accelerates corrosion, making combined anti-biofilm and anti-corrosion strategies essential for marine infrastructure protection. In this study, we developed a composite coating system in which silver-loaded nano-sized zeolite particles are dispersed within an alkoxysilane resin matrix (Permeate), and evaluated its performance against both biofilm formation and corrosion under laboratory and real marine conditions. Nano-zeolite type A particles, with diameters of several tens of nanometers, were employed as carriers for silver to achieve uniform dispersion and sustained antimicrobial function within the coating. The composite coatings were applied over chromium-plated carbon steel (Cr/SS400) substrates. Three specimen conditions were compared: bare SS400, Cr/SS400, and Permeate-coated Cr/SS400. Laboratory biofilm assays using Staphylococcus epidermidis with crystal violet staining according to the ISO 4768:2023 protocol demonstrated that the nano-zeolite dispersed Permeate coating significantly reduced biofilm formation on glass substrates compared to uncoated controls. Marine immersion tests were conducted at Marina Kawage, Mie Prefecture, Japan, over a one-month period. While macrofouling organisms were not clearly observed on any specimen during this period, all substrates exhibited biofilm-accelerated corrosion. The degree of corrosion decreased in the order SS400 > Cr/SS400 > Permeate/Cr/SS400, showing strong correlation with the reduction in biofilm quantity. These results demonstrate that the nano-zeolite-mediated silver dispersion approach effectively suppresses biofilm formation in both laboratory and marine environments, thereby mitigating biofilm-accelerated corrosion. The alkoxysilane resin composite coating offers a promising PFAS-free antifouling strategy for marine applications.
See more of: Corrosion and Environmental Degradation (AMPP)
See more of: Surface Engineering & Protective Coatings