Time-resolved infrared radiometry (TRIR) using a focal-plane array for characterization of hidden corrosion

A time-resolved infrared radiometry technique is developed which is applicable to detection of hidden corrosion in airframe structures and which implements an InSb focalplane array. The TRIR method can measure the loss of skin thickness due to corrosion and can also detect second layer corrosion when a sealant material is present at a lap joint. It has also been shown that the presence of corrosion product can be detected on the back surface of an aluminum plate free standing in air. Other experimental studies suggest that the presence of corrosion product, corrosion thinning of the plate and morphology changes at the aluminum-corrosion layer interface all affect the TRIR temperature-time signature. This raises the possibility of separating these contributions experimentally.