Application of quantum dots as a fluorescent-penetrant for weld crack detection

Fluorescent penetrant inspection (FPI) is a nondestructive testing method for detecting discontinuities and is one of the most promising methods for warning of a possible near future failure. In this paper we present semiconductor quantum dots (QDs) suspended in a colloidal solution as the fluorescent penetrant to detect cracks in weldments. QDs are nano-metric structures that fluoresce under ultraviolet-visible radiation and can be tuned for specific situations. Use of QDs as penetrants adds flexibility to FPI with the advantages of using environmentally friendly chemicals, needing fewer steps for preparation and pre/post cleaning, and achieving simpler or cheaper data collection. The principles of the technique along with the applicability to weld damage and crack inspection will be discussed.