Advanced NDE System for Detecting Hidden Corrosion

We propose the development of a sensitive, portable and noninvasive corrosion monitoring instrument with the ability to detect ongoing corrosion and to evaluate the damage caused by corrosion, especially hidden corrosion which cannot be detected visually. Structural applications particularly relevant to the Navy are airframe and ship structure components which incorporate metal laminates or have inaccessible regions separated by thin-walled shells from the exterior. Eddy current techniques using a sensitive magnetoresistive (MR) sensor in conjunction with an applied field will be used to assess material damage due to corrosion. In addition the magnetic fields generated by the electrochemical currents due to ongoing corrosion will also be measured. The MR sensor, by virtue of its small size, its broad detection bandwidth, and its sensitivity at low frequencies lends itself ideally to a corrosion detector which is compact and which can be used to detect hidden and deep corrosion damage, not possible with frequency-dependent induction coil sensors. In Phase I we will demonstrate the ability of a MR sensor-based device to detect both corrosion damage and ongoing corrosion activity. In Phase II we will build a prototype and test it in the field.