Assessment of Corrosion Resistance of Nano-Enhanced Steel in Marine Environments

Thesis Abstract

The durability of steel structures in marine environments remains a critical challenge due to the pervasive issue of corrosion, leading to significant economic costs and safety concerns worldwide. Traditional steel alloys, although widely used, exhibit limited resistance to chloride-induced corrosion in saline conditions, which accelerates material degradation and reduces structural lifespan. This study aims to evaluate the effectiveness of nano-enhanced steel in mitigating corrosion under marine conditions, with specific objectives to synthesize and characterize nano-enhanced steel samples, assess their corrosion performance compared to conventional steel, and identify the underlying mechanisms responsible for improved corrosion resistance. Employing an empirical, field-based research design, the study integrates laboratory synthesis and characterization techniques with in-situ marine exposure tests. A total of 120 steel samples, comprising 60 nano-enhanced steel specimens fabricated through electrodeposition with varying nanoparticle concentrations (0.5%, 1.0%, 2.0%), and 60 control samples of conventional steel, were selected based on a stratified random sampling method. These samples were subjected to exposure in a coastal marine environment over a 12-month period, with periodic assessments conducted at three-month intervals to monitor corrosion progression. Data collection involved multiple instruments and techniques, including electrochemical impedance spectroscopy (EIS), potentiodynamic polarization tests, scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). These methods provided quantitative metrics of corrosion rate, corrosion potential, and surface morphology, complemented by qualitative insights into corrosion mechanisms. The validation and reliability of measurement instruments were ensured through calibration protocols and repeated measurements, adhering to standard ASTM testing procedures. Data analysis encompassed statistical analyses such as ANOVA to compare corrosion rates across different nanoparticle concentrations, regression analysis to model the relationship between nanoparticle content and corrosion resistance, and thematic analysis of surface morphology observations. The theoretical framework integrates the passivation theory and the nano-reinforcement theory, elucidating how nanoparticle incorporation influences film formation and barrier properties at the microstructural level. A conceptual model illustrating the interaction of nanoparticles within the steel matrix and its impact on corrosion resistance was developed based on empirical data. Expected findings suggest that nano-enhanced steel exhibits a statistically significant reduction in corrosion rate compared to conventional steel, with optimal performance observed at 1.0% nanoparticle concentration. The improved corrosion resistance is hypothesized to stem from the formation of a more uniform and adherent passive film, enhanced barrier properties due to nanoparticle incorporation, and microstructural refinement observed via SEM and XRD analyses. These findings are anticipated to demonstrate correlations between nanoparticle concentration, surface microstructure, and corrosion performance, thereby contributing to the understanding of nano-materials in corrosion mitigation. The study contributes to existing knowledge by providing empirical evidence of nano-materials’ efficacy in real-world marine environments, integrating microstructural, electrochemical, and macroscopic corrosion assessments. It advances theoretical understanding of nano-reinforced corrosion barriers and offers practical insights for the development of more durable marine steel structures. The main conclusion underscores the potential of nano-enhanced steel to improve service life and reduce maintenance costs of marine infrastructure. Recommendations include further exploration of long-term performance, evaluation of different nanoparticle types (such as TiO2, SiO2), and pilot-scale implementation in structural applications. Future research should focus on lifecycle assessment and environmental impacts of nanoparticle incorporation to support sustainable material development in marine engineering.