Susceptibility of aluminum alloys to corrosion in simulated fuel blends containing ethanol

The compatibility of aluminum and aluminum alloys with synthetic fuel blends comprised of ethanol and reference fuel C (a 50/50 mix of toluene and iso-octane) was examined as a function of water content and temperature. Temperatures examined ranged between 20 °C and 200 °C and water content ranged between sub 50 ppm and 10% by volume. Commercially pure wrought aluminum and several cast aluminum alloys were observed to be similarly susceptible to substantial corrosion in dry (<50 ppm water) ethanol. Corrosion rates of all the aluminum materials examined were accelerated by increased temperature and ethanol content in the fuel mixture, but inhibited by increased water content. Substantial corrosion was observed only at temperatures exceeding 78 °C, the boiling point of ethanol. Pretreatments designed to stabilize passive films on aluminum increased the incubation time for onset of corrosion, suggesting film stability is a significant factor in the mechanism of corrosion.