Corrosion at the liquid air interface (LAI) was first observed on ASTM A537 carbon steel in nuclear waste simulants in the laboratory, and this triggered a series of investigations in an attempt to better understand this new corrosion phenomenon. Research has been carried out to identify the key factors that make the A537 steel susceptible to liquid air interface corrosion (LAIC) and possibly further the understanding of the LAIC mechanism. These include differential oxygen concentration, local pH, and local nitrite/nitrate concentrations in the meniscus region. In the meantime, a reliable quick laboratory screening technique was being developed with the aim to distinguish the conditions that will initiate LAIC from those that do not. This includes cyclic potentiodynamic polarization (CPP) experiments with (1) partially-immersed specimens and (2) fully-immersed multiple crevice assembly (MCA) specimens. CPP experiments with partially-immersed specimens offer a direct and intuitive observation of LAIC. However, different sample geometries yielded different CPP results in the same waste simulant. CPP experiments with MCA electrodes were performed because of the concurrence and similarity between crevice corrosion and LAIC observed. These approaches were evaluated in a variety of nuclear waste simulants and the results were compared and discussed.

Subject
Test methods, Nitrites, Repassivation potentials, Corrosion initiation, Hysteresis, Bulk solution, Nitrates, Crevice corrosion, Specimen preparation, Carbon steel, Immersion, Electrodes, Electrode potential
Keywords:
liquid air interface corrosion, nuclear waste simulant, carbon steel
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2013
Association for Materials Protection and Performance (AMPP)
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