Defect Detection in Narrow Bore Components with Quantum Dot Liquid Penetrants

Physical Sciences Inc. will develop a liquid penetrant system based on colloidal quantum dots (QDs) and a high resolution dual-channel fiberscope to enable nondestructive examination of micron sized cracks in the bore evacuator holes of gun tubes. The proposed ligand-free QDs will eliminate hydrocarbon contaminants found in conventional penetrants and mitigate hydrogen embrittlement of steel components. In Phase I, we will establish the feasibility of the approach by demonstrating the synthesis of ligand free, water soluble QDs with emission quantum yields greater than 30%, while in parallel, developing a system model for the excitation and detection of the QDs. We will validate the system model via proof-of-concept fluorescence imaging of the QDs applied to precision machined defects in steel coupons. In Phase II, we will pursue QD material scale-up and develop an advanced penetrant system prototype that includes an applicator for applying the QD penetrant into bore holes and a rugged fiberscope for imaging QD emission. At the end of Phase II, we will demonstrate the ability of the penetrant system to quantify the crack depth of bore evacuator holes based on QD emission intensity using Government furnished gun tubes.