Early detection of epoxy coated St-۳۷ underlying corrosion by fluorescent indicator

In the present work, the application of ۸-hydroxyquinoline (۸-HQ) as a ferric ion sensitive indicator, in epoxypolyamine coating was investigated. Having turn-on mechanism and showing no prematurely fluorescence when mixed with the coating precursors make ۸HQ useful for detecting undercoating corrosion of St-۳۷ which is covered by epoxy coating. The effect of different concentrations of ۸HQ(۰.۰۵,۰.۱,۰.۵,۱w.t%) in epoxy coating, on corrosion detection, optical, electrochemical and adhesion properties of applied coating were studied respectively by fluorescence microscopy, UV- Visible spectroscopy, electrochemical impedance spectroscopy and Pull-off methods. In the process, the sample with ۰.۱w.t% of ۸HQ not only, showed acceptable corrosion detection performance, but also was good in optical, electrochemical and adhesion properties.

Keywords:

۸-hydroxyquinoline , Corrosion indicator , Epoxy coating , Fluorescence microscope , Electrochemical Impedance Spectroscopy , ۸-هیدروکسی کوئینولین , شناساگر خوردگی , پوشش اپوکسی , میکروسکوپ فلورسنس , آزمون امپدانس الکتروشیمیایی ,