ENHANCING CORROSION RESISTANCE OF WELDED METALS WITH SELF-HEALING COATINGS: EVALUATION OF EPOXY FORMULATIONS AGAINST MICROBIOLOGICALLY INFLUENCED CORROSION

Abstract

Corrosion of welded metals poses a significant challenge in industrial contexts, especially when joints are exposed to harsh environmental conditions. Although traditional corrosion protection methods, such as coatings, offer a cost-effective solution, their effectiveness can be undermined by aggressive corrosive agents or microorganisms. Recent advancements in self-healing coatings present a promising alternative, as these coatings can autonomously repair and prevent corrosion, thereby extending the service life of the metal. Microbiologically influenced corrosion (MIC), driven by microorganisms such as Pseudomonas aeruginosa, accelerates metal degradation in nutrient-rich simulated sea water medium (NRSS). This study aims to evaluate the efficacy of self-healing coatings in mitigating MIC on dissimilar welded metal substrates. Specifically, it assesses the performance of epoxy coatings incorporating 7 wt.% microcapsules and 10 wt.% chitosan particles compared to pure epoxy coatings. The coatings were applied to welded substrates and subsequently inoculated with Pseudomonas aeruginosa for 3, 7,14, 28 and 42 days immersion test. Field emission scanning electron microscopy (FESEM) and energy dispersive spectroscopy (EDS) were used to analyze biofilm formation, bacterial cell morphology, and corrosion precipitates. The results indicate that the self-healing coatings containing microcapsules and chitosan particles significantly improved corrosion protection, as evidenced by FESEM images showing reduced bacterial adhesion and biofilm formation. Chitosan particles, with their positively charged nitro-groups and high surface area, proved particularly effective in inhibiting biofilm development and exhibiting biocidal properties.