Measurements of breakdown potentials and electrochemical impedance have been conducted for Alloy 600 in a 0.03 M NaCl solution with and without 0.01 molar sulfur species additions at 100-250° C by using a new crevice corrosion test cell. Specimen was sandwiched between two grooved Teflon washers in this test cell to create the desired crevice sites. Addition of 0.01M Na2SO4 increased the breakdown potentials by more than 120 mv at the temperature range from 100 to 250° C. Na2S2O3 showed similar but less inhibitive effects at temperature lower than 200° C, while increasing temperature up to 250° C caused a dramatic decrease in breakdown potential of crevice corrosion. The AC impedance measurements at 200°C indicated that sulfur compound additions would suppress the passive film resistance and promote the crevice corrosion. The AC impedance behavior of creviced Alloy 600 changed with exposure time and different sulfur compounds additions.

Subject
Nickel based alloys, Sodium chloride, Impedance, Chloride solutions, Crevices, Impedance measurements, Sodium chloride solution, Thiosulfate, Sodium, Crevice corrosion, Immersion, Alloys, Breakdown potential
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1988
Association for Materials Protection and Performance (AMPP)
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