Development of an electrochemical impedance spectroscopy sealant test: II. Conductive sealants

Abstract Distinguishing between sealants and providing laboratory prognostic tools is essential for qualifying new sealants. Current test methods do not provide adequate discrimination between sealants. A laboratory test based on electrochemical impedance spectroscopy (EIS) supplemented by adhesion strength measurements and examination of sealed, bimetallic surfaces is an approach for discriminating between sealants. This approach gives an early indication of sealant performance so that suitable materials can be chosen for aircraft and other applications. Sealant specimens (three conductive sealants) underwent hot-salt-water exposure followed by EIS inspection, pull strength measurements, and visual inspection. Several specimens exhibited a temporary loss of conductivity during exposure. The maximum low-frequency impedance was correlated to both corrosion inside the sealant ring and pull strength. Keywords: SEALANTELECTROCHEMICAL IMPEDANCE SPECTROSCOPYSCREENING TESTMOISTURE