Nanostructure and local properties of oxide layers grown on stainless steel in simulated pressurized water reactor environment

The morphology and local electrical resistance of duplex oxide films formed on 316L stainless steel at 325(circle)C in simulated primary coolant of pressurized water reactor have been investigated at the nanometre scale with Conductive Atomic Force Microscopy. The electrical resistance varies over 1 order of magnitude for most oxide grains and over 2-3 orders of magnitude locally at grains and grain boundaries. This is rationalized in terms of local variation of the composition and thus resistivity of the mixed Fe(II)-Cr(III) barrier inner layer of the oxide films with grain boundaries of the outer layer possibly promoting Cr(III) enrichment. (C) 2014 Elsevier Ltd. All rights reserved.