Corrosion Resistance of Automotive Ecological Fuel Tanks in Contact With Hydrated Ethanol Fuel 2012-36-0387

For metallic tanks in contact with aqueous solution, it is always observed the presence of electrochemical corrosion. This process can cause both economic and environmental damage. In the automotive industry, fuel tanks systems have been studied in order to propose new materials to replace the plastic tanks or tanks with metallic coatings. Plastic tanks have the disadvantage of not being recyclable. In the other hand, for metallic coated tanks, tin is used as a coat material and, for this reason, the external tank side must be painted, making its productive process more expensive and generating higher amount of waste. Nowadays, organic-metallic coated tanks, in which, nickel and aluminum are the metals present, can be found. These coatings show potential application; because they do not use heavy metals in their composition and they do not require external painting, allowing a lower production cost. In this work, the electrochemical behavior of EEP mild steel, both coated with organic-metallic compound and without coat, when in contact fuel hydrated ethylic alcohol, was evaluated. The evaluation was carried out using electrochemical impedance spectroscopy technique. Steel substrate in contact with alcohol system was associated with an electric circuit with solution resistance in series with the interfacial resistance and in parallel with non ideal capacitance of the electric double layer. The polarization resistance value for this system was 132.7 kOhm. On the other hand, polarization resistance value for the organic-metallic coating system in contact with alcohol was 2.37 MOhm. This shows that, organic-metallic coated steel system is approximately 18 times more resistant to polarization, in fuel hydrated ethylic alcohol solution, than non coated steel. This is a promising result, once these coatings presented good ability to protect steel substrates against corrosion, and they can be an environmental safe alternative for automotive tanks production.