Microbiologically influenced corrosion in uncoated and coated Mild Steel

The study aimed to investigate the corrosion performance of Zn-Ni-Cu and Zn-Ni-Cu-TiB₂ coatings in the microbial-induced environment (E-Coli, ATCC 25922, and 3.5%NaCl solution). Zn-Ni-Cu and Zn-Ni-Cu-TiB₂ were surfaces coated on an ASTM A-36 Steel substrate utilizing a high-velocity oxy-fuel (HVOF) thermal spray process. Immersion tests following ASTM G-31, and ASTM G1-03, standards were performed in Escherichia Coli (E-Coli, American Type Culture CollectionATCC25922) bacteria medium. The effect of Zn, Ni, and Ti was studied in preventing microbial-induced corrosion.SEM, and XRD analysis before and after helped to understand the morphological and structural changes in coated/uncoated ASTM A-36 steel. Various forms of rust were ascertained in XRD analysis. The inclusion of Zn and Cu inhibited bacterial attachment to the coated surface, hence preventing significant corrosion of the underlying substrate. The coatings performed effectively and inhibited bacterial growth. The uncoated ASTM A-36 Steel specimen showed well-developed bacterial colonies on the surface and in the solution medium. All forms of rust were reported in XRD analysis for uncoated ASTM A-36 steel while few forms of rust were reported in coated ASTM A-36 steel.Electrochemical impedance spectroscopy (EIS) and Tafel polarization in Escherichia coli (E-Coli, ATCC 25922) medium demonstrated that the coated samples had greater corrosion resistance than the uncoated ASTM A-36 Steel specimens. The higher corrosion potential (Ecorr) values of the two coated samples indicated improved anodic protection.