Corrosion risk and material degradation of copper-zinc alloys in aged biodiesel fuel systems

This study investigates the corrosion behavior of copper-zinc alloys in aged canola biodiesel, with an emphasis on fuel system reliability and long-term material performance in renewable energy applications. A combination of analytical techniques, including scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), and gas chromatography–mass spectrometry (GC-MS), was employed to elucidate corrosion mechanisms and material–fuel interactions. Compared with conventional diesel, biodiesel and its blends significantly accelerated both localized and generalized corrosion, characterized by severe pitting, surface degradation, and the formation of oxide layers (primarily Cu₂O and CuO). These phenomena threaten the structural integrity and operational safety of fuel handling systems. Although the antioxidant additive tertiary butylhydroquinone (TBHQ) partially inhibited oxide formation, it did not provide complete protection against degradation. Furthermore, selective corrosion between copper and zinc was observed, suggesting galvanic effects and underscoring the limited long-term efficacy of antioxidant-based mitigation strategies. By contrast, copper-zinc alloys exhibited good compatibility with diesel fuel, showing negligible surface damage after extended exposure. Overall, these findings underscore the urgent need for optimized alloy compositions and more robust additive systems to enhance corrosion resistance and ensure the safe use of biodiesel in industrial fuel systems.