Accession Number : ADA192481

Title :   A Critical Review of IR Drops and Electrode Potentials within Pits, Crevices and Cracks.

Descriptive Note : Annual rept.,

Corporate Author : PENNSYLVANIA STATE UNIV UNIVERSITY PARK DEPT OF MATERIALS SCIENCE AND ENGINEE RING

Personal Author(s) : Pickering, Howard W

PDF Url : ADA192481

Report Date : Jan 1988

Pagination or Media Count : 39

Abstract : The experimental data showing variations in electrode potential in actively growing pits, crevices and cracks are reviewed. Direct potential measurement, proton discharge within the local cell when thermodynamically unfavorable at the outer passive surface, faceting of the pit and crevice walls, and the presence of an active/passive boundary conclusively prove that pitting and crevicing of iron occurs when the electrode potential within the cell is below (less noble than) the Flade or passivation potential of the crevice solution. Low pH and Cl and other aggressive ions, are proposed to increase both the stability and rate of localized corrosion by increasing the size of the active loop and/or magnitude of the passive current of the cavity solution.

Descriptors :   *BOUNDARIES, *CAVITIES, *CRACKS, *ELECTRODES, *PASSIVE SYSTEMS, *ELECTRICAL RESISTANCE, CELLS, CORROSION, EXPERIMENTAL DATA, EXTERNAL, IONS, IRON, LOOPS, MEASUREMENT, PASSIVITY, PH FACTOR, PROTONS, RATES, SOLUTIONS(GENERAL), SURFACES, WALLS

Subject Categories : Physical Chemistry
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE