NDE applications of SQUID magnetometry to electrochemical systems

A technique utilizing state-of-the-art SQUID magnetometers for noninvasive evaluation of the electrochemical reactivity of materials has been extended to practical systems. For example, sensitization of type-304 stainless steel has been identified. Magnetic signals produced by sensitized and unsensitized samples in acid demonstrate clear differences between the two types of samples. As a second example, electrodeposition of zinc, simulating recharging of Zn/Ni and Zn/Ag batteries, has been noninvasively monitored via magnetic signals. Disturbances in the current distribution over time, caused by nonuniform deposition, have been detected and compared to simulations of dendritic growth. Further investigations will be enhanced by increased flexibility, sensitivity, and spatial resolution available in a prototype SQUID instrument being developed.