Materials and Corrosion 2/2012

Abstract

Cover: The cover shows an illustration of the experimental set up for in‐situ investigations of the anodic metal dissolution under ECM conditionsA specially designed channel flow cell is placed under an optical microscope with long distance lens. A gold disc with a small conical glass lens in the centre is embedded in the glass lid of the channel flow cell and works as cathode. The sample is placed beneath the cathode and works as anode. The gap width of the channel amounts 0.35mm. A maximum electrolyte flow rate of 12.3m/s was realized. The anodic dissolution was carried out by current controlled pulses. The test assembly allows the observation of the surface topography development of the anode as well as possible interface reactions (e.g. gas evolution). More detailed information can be found in: M. Schneider, S. Schroth, N. Schubert, A. Michaelis, In‐situ investigation of the surface‐topography during anodic dissolution of copper under near‐ECM conditions, Materials and Corrosion 2012, 63, 96.

Anodic dissolution of cobalt in aqueous sodium nitrate solution at high current densities

“…The ECM‐experiments were carried out in a specially designed channel flow cell with a 2‐electrode arrangement, which was firstly introduced in Ref. . The intention of the cell design is the possibility to observe the sample surface during the ECM‐experiment in situ and in‐operando, respectively.…”

“…The intention of the cell design is the possibility to observe the sample surface during the ECM‐experiment in situ and in‐operando, respectively. The cell design and the experimental limits have been recently described in detail . The flow channel cell was connected with a power source GEN60‐25 (TDK‐Lambda) and a gear pump ISM 405 (Ismatec) to realize the electrolyte flow.…”

“…Unfortunately, Davydov et al did not report on the surface texture of the samples, possible side reactions or current efficiencies. Recently, Schneider et al investigated the kinetic of the cobalt dissolution in association with the surface texture development at low current densities (5 and 10 A/cm 2 ) in NaNO 3 . The reported results can briefly summarized as follows: Co dissolves actively. The current efficiency is approximately 100%. The surface texture is strongly influenced by defects and the crystallographic orientation of the crystallites …”

“…Again, a special issue is the investigation of the interplay between the dissolution parameters and the microstructure of cobalt. A special electrochemical cell design allows the observation of the sample surface during the electrochemical experiments . In conclusion, this work should answer the following questions: What is the kinetic mechanism of the cobalt dissolution at the notified current densities? Do side reactions take place and are there preferred sites on the surface dependent on the crystallographic orientation? Is the surface texture development associated with the anodic dissolution at the notified current densities dependent on the crystallographic orientation? …”