| Budget Amount *help |
¥18,980,000 (Direct Cost: ¥14,600,000、Indirect Cost: ¥4,380,000)
Fiscal Year 2015: ¥3,380,000 (Direct Cost: ¥2,600,000、Indirect Cost: ¥780,000)
Fiscal Year 2014: ¥4,030,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥930,000)
Fiscal Year 2013: ¥11,570,000 (Direct Cost: ¥8,900,000、Indirect Cost: ¥2,670,000)
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| Outline of Final Research Achievements |
A sensing plate for the simultaneous measurements of pH and chloride ion concentration was newly developed. Terbium-dipicolinic acid complex and quinine sulfate were used to measure the pH and chloride ion concentration, respectively. In the incubation period of the crevice corrosion, the pH inside the crevice gradually decreased from 3.0 to ca. 2.5, and the chloride ion concentration increases from 0.01 to ca. 0.18 M. The generation of the micro-pit led to a sharp decrease in pH to below 0.5 and an increase in the chloride ion concentration to above 4 M. In addition, the electrode potential inside the crevice was expected to be in the passive-active transition region of stainless steels. The local dissolution caused by the passive-active transition in a weak acid environments was likely to be the initiation of the crevice corrosion of stainless steels.
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