Transpassive dissolution of iron and nickel in 5 M NaClO3 and 6 M NaNO3 has been investigated in a flow channel cell allowing for controlled hydrodynamic conditions. Applied current density ranged up to 33 A/cm2, applied flow rates up to 1760 cm/s. The influence of mass transport on current efficiency for metal dissolution, apparent anode potential and surface microtextures resulting from dissolution was investigated. Obtained results confirm that all these parameters are influenced by mass transport processes but secondary effects such as gas evolution, hydroxide precipitation, homogeneous chemical reactions, or joule beating in many cases interfere with convective transport phenomena in the solution. Optimisation of ECM operating conditions and modelling for tool design applications require intimate knowledge of the influence of hydrodynamic conditions on the electrochemical behavior of the metal-electrolyte combination employed.
Dr. Madhav Datta and Landolt, D., “On the role of mass transport in high rate dissolution of iron and nickel in ECM electrolytes—II. Chlorate and nitrate solutions”, Electrochimica Acta, vol. 25, pp. 1263–1271, 1980.