Corrosion- and Electrochemical Dissolution Behavior of Cast Iron Measured with Different Electrochemical Cell Types

摘要

The corrosion behavior and the electrochemical dissolution of three different cast iron types and onehigh purity iron sample in NaNO3 electrolyte (25C, 1 M, pH: 7) were investigated by comparing threedifferent cell setups: a relatively simple beaker-cell, a small-sized capillary flow-cell and a high- current gap-cell. The electrochemical cell types differ in electrolyte flow rate, size of the measuredsample surface and applied current density. The work aims at investigating the electrochemicaldissolution of inclusion containing materials (cast iron) and the evolution of a strategy that allows thedetermination of process parameters used for the design of electrochemical machining (ECM)processes. All samples were characterized by X-ray diffraction, energy-dispersive X-ray spectroscopyand scanning electron microscopy. Electrochemical characterization was carried out by cyclicvoltammetry and chronoamperometry experiments. It could be shown that the electrochemicaldissolution behavior was dominated by the matrix structure and the geometry of the included graphiteparticles. The determination of corrosion potential and -current were mainly influenced by theelectrolyte flow rate. Our new flow cell design (gap-cell) is suited for an easy and fast electrochemicalcharacterization of materials under high current densities.