The initiation of traveling pulses from self-organized oscillations in the iron–nitric acid system

The spatio–temporal dynamics of dissolution patterns on low-carbon steel wires submerged in nitric acid solution are studied in an electrolytic cell by means of optical detection. The cathodic steel wire can segregate into different macroscopic domains. With increasing distance from the external anode, these domains are characterized by constant dissolution, rapidly pulsating oscillations, excitable behavior, and constant passivity. For nitric acid concentrations between 10.5 M and 12.0 M, the fast oscillations trigger traveling waves that experience propagation failures far from the anode. The rhythm of successful wave generation is typically slower and less regular than the rhythm of the rapid oscillations.