Corrosion Kinetics of Nickel-base Alloys in Simulated BWR Conditions under High Flow Velocity
2013 (English)Conference paper (Refereed)
Corrosion-induced material degradation of nickel-base alloys is a critical issue of material integrity and plant operation safety. It is therefore important to determine alloy corrosion rates and to examine corrosion resistant properties of the oxide films formed on the alloy surfaces. This paper contributes to a corrosion kinetic study on nickel-base alloys 82, 182 and 600 in a specially constructed loop system capable of simulating BWR water environments under high flow velocity. The corrosion rate data are derived from measurements of weight changes of test coupons, oxide thicknesses with infrared ellipsometry, and microstructures of oxide films with high resolution electron microscopy. For the alloys examined, corrosion rates decreased with time, suggesting that the formed oxide films were likely protective. Although the overall thicknesses of the oxide films on Alloy 82 and 600 were vastly different from each other, they corroded equally much after nine weeks exposure. Comparing the corrosion rates for Alloys 182 and 600, on the other hand, one finds that the very thick oxide films formed on Alloy 600 did not make the alloy corrode more slowly but more rapidly. These observations indicate that the overall thickness of oxide scales, being largely porous, did not contribute to alloy corrosion protection. The possible rate-limiting step occurring in the inner-most thin but tenacious oxide films at the metal/oxide interface regions is briefly discussed.
Place, publisher, year, edition, pages
nickel-base alloys, corrosion, rates, kinetics, oxide films, Alloy 82, Alloy 182, Alloy 600, infrared ellipsometry, BWR, SEM, TEM, FIB
IdentifiersURN: urn:nbn:se:liu:diva-108488OAI: oai:DiVA.org:liu-108488DiVA: diva2:730555
16th International Conference on Environmental Degradation of Materials in Nuclear Power Systems- Water Reactors, 11-15 August 2013, Asheville, NC, USA