Degradation of automotive materials upon exposure to sunflower biodiesel

• The susceptibility to corrosion of some materials exposed to biodiesel was evaluated.
• The corrosiveness of biodiesel was higher as compared to that of petrodiesel.
• At 25 °C, corrosion in biodiesel decreases in order; copper>mild carbon steel>aluminum.
• The higher moisture content of sunflower biodiesel promoted a high corrosion.

Corrosion and a high susceptibility to oxidation or autoxidation are the main concerns associated to biodiesel compatibility issues. In this research, an aluminum, copper and ferrous alloy was exposed to sunflower biodiesel (B100), biodiesel blend (B20) and conventional petroleum diesel (B0) and their corrosion behavior and the corrosion products were evaluated after static immersion tests in B0, B20 and B100 at room temperature and 60 °C for 3000 h.After immersion tests, corrosion behavior rates were calculated based on weight loss measurements and changes in the surface morphology, chemical microanalysis were studied by scanning electron microscopy (SEM) with energy dispersive X-ray analysis (EDS) and corrosion products were detected by X-ray diffraction (XRD). Fuels were characterized by measuring the total acid number (TAN), water content, density and viscosity. It was found that sunflower biodiesel was more corrosive than diesel fuel and the metal corrosion and degradation of fuels depended on temperature. Copper was found to be more susceptible to corrosion in biodiesel as compared to mild carbon steel and aluminum.