Conducting Electrochemical Measurements in Fuel-Grade Ethanol Using Microelectrodes

Corrosion and stress corrosion cracking of carbon steel in biofuels are a concern with the increase in the usage of ethanol as an alternate fuel. Electrochemical studies in highly resistive electrolytes (e.g., ethanol) traditionally have been conducted with the addition of a supporting electrolyte. The present work used microelectrodes to study the electrochemical behavior of carbon steel in fuel-grade ethanol (FGE). Owing to the small electrode size, a small magnitude of current was measured that reduces ohmic potential drops and makes it possible to perform electrochemical experiments in the absence of a supporting electrolyte. The present method was used to investigate the effect of water and chloride on the corrosion of carbon steel in FGE. The results were generally consistent with those obtained in alcoholic solutions when a supporting electrolyte was used. Additionally, the microelectrode method was used to evaluate the electrochemical response of steel in the presence of a stress corrosion cracking inhibitor.