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Indexed by:Journal Papers

Date of Publication:2020-02-07

Journal:JOURNAL OF NONDESTRUCTIVE EVALUATION

Included Journals:EI、SCIE

Volume:39

Issue:1

ISSN No.:0195-9298

Key Words:Stainless steel; Iron contamination; Color-change indicator; Corrosion

Abstract:Inspection on surface iron contaminants of stainless steel is a critical process during the manufacturing of nuclear power facilities. Highly sensitivity of image recognition on iron contamination was achieved for 316L stainless steel by adding cellulose ether and silicone polyether into phenanthroline color-change indicator. Those indicators were also compared to the RCC-M (Design and Construction Rules for the Mechanical Components of PWR Nuclear Islands) recommended blue-dot solution. The indicator sensitivity and stability of phenanthroline solutions are superior to the blue-dot solution on the bases of the measured color-change degree. The sensitivity and the image recognition ratio are improved by the additives from the view point of the reconstructed 3D image of red pixel. Based on a hypothesis of iron ion-controlled process during coloration reaction, a linear relationship with a constant slope between redness degree a* and iron concentration in double logarithm coordinates was evidenced in all the phenanthroline indicators. From potentiodynamic polarization curves, the breakdown potential and corrosion potential decreased with increasing the redness degree.