Energy Technology Data Exchange (ETDEWEB)

The passivity and breakdown of passivity of 1018 carbon steel in propylene carbonate (PC) and 1,2-dimethoxyethane (DME) mixtures with 0.5 molar lithium hexafluoroarsenate supporting electrolyte were examined via several electrochemical and surface analytical methods. The PC-DME/0.5 M LiAsF{sub 6} mixtures ranged from 10 to 90 mol % PC. The results from the PC/DME mixtures were compared to passivating mechanisms found in pure PC and DME solutions. In PC-rich mixtures, the breakdown of passivity occurred near the oxidation potentials of either organic solvent. Premature breakdown of the carbon steel in PC-DME mixtures occurred at sulfide inclusions as was observed earlier in PC/0.5 M LiAsF{sub 6} solutions although passive films attempted to form at these inclusion sites in mixtures containing at least 10 mol % DME. As the DME content increased in the PC-DME mixtures, the passive films formed on bare steel surfaces possessed an increasing polymer ...