Corrosion studies in low conductivity media: carbon steel in ethanol media

摘要

The corrosion studies in aqueous media through electrochemical techniques are well established and the conditions that limit their use are also well known. These techniques are very useful and allow verifying the corrosion susceptibility of metallic materials in a specific aqueous media as well as obtaining information related to the corrosion kinetic of the studied systems. However, in organic media, these techniques are not always used due to their very low conductivity (< 1.0 (iS/cm). Nowadays, ethanol fuel has aroused the interest of professionals of the scientific, the technological and the commercial areas due to its broad use in the national market and also due to its great use as a renewable energy source in the international market. In Brazil, corrosion studies in ethanol through electrochemical techniques have been conducted for more than 30 years. However, up to now, the interpretation of the obtained results is not well established. The present work has a goal to verify the ethanol corrosiveness through electrochemical impedance spectroscopy techniques using carbon steel as a working electrode and AISI 316 stainless steel as both an auxiliary electrode as well as a quasi-reference electrode. Absolute ethanol was studied as well as absolute ethanol with 1 % of water, with and without the addition of some of the impurities cited in ASTM D 4806 (2006). The results indicated that absolute ethanol and absolute ethanol with 1 % of water presented low aggressivity and the addition of impurities caused a slight increase in the ethanol aggress ivity. ethanol; corrosiveness; electrochemical impedance