A SQUID study of magnetic fields resulting from in situ corrosion reactions

Detection of magnetic fields associated with corrosion currents provides a new concept for corrosion monitoring. We have used superconducting quantum interference device (SQUID) magnetometry to study the corrosion of the Co-C r-Mo alloy in a hemispherical water layer. Corrosion was initiated by the i ntroduction of oxygen gas. The SQUID responded systematically to oxygen-all oy interactions, indicating the presence of corrosion-induced magnetic fiel ds. Also, an immediate magnetic field change was observed when liquid phase contacted the metal one provided both phases were of different temperature s. Such a magnetic field generation by the metal/liquid interface was expla ined in terms of internal thermoelectric currents. (C) 1999 The Electrochem ical Society. S1099-0062(99)05-067-1. All rights reserved.