Remote detection of corrosion activity by SQUID magnetometry across a multiphase medium under electrolyte flow conditions

Hydrodynamic induction of magnetic fields on AA2024 sample corroding in NaOH solutions was studied by a Superconducting Quantum Interference Device (SQUID) magnetometer operating in liquid helium with a spatial resolution of approximately 1 mm. The hydrodynamic generation of magnetic fields was explained in terms of electronic and ionic currents induced by corrosion potential gradients within the sample due to different solution flow velocities. The intrinsic magnetic activity of the electrolyte flow was significantly less than that of the corroding sample. The measurements demonstrated a unique capability of magnetometry to sense corrosion remotely and across the integrated media consisting of gaseous and solid dielectrics (air, plastics), electronic conductor (aluminum alloy) and ionic one (solution).