Electrochemical techniques, anodic impedances

Corrosion test methods can be divided into electrochemical and non-electrochemical methods. Among the electrochemical techniques that have been used successfully for corrosion prediction are potentiodynamic polarization scans, electrochemical impedance, corrosion current monitoring, controlled potential tests for cathodic and anodic protection, and the rotating cylinder electrode for studies of velocity effects [3i,32]. Though not literally a test, potential-pH (Pourbaix) diagrams have been used as road maps to help understand the results of other tests. 

The UPD and anodic oxidation of Pb monolayers on tellurium was investigated also in acidic aqueous solutions of Pb(II) cations and various concentrations of halides (iodide, bromide, and chloride) [103]. The Te substrate was a 0.5 xm film electrodeposited in a previous step on polycrystalline Au from an acidic Te02 solution. Particular information on the time-frequency-potential variance of the electrochemical process was obtained by potentiodynamic electrochemical impedance spectroscopy (PDEIS), as it was difficult to apply stationary techniques for accurate characterization, due to a tendency to chemical interaction between the Pb adatoms and the substrate on a time scale of minutes. The impedance... 

Y. Tsutsumi, A. Nishikata, T. Tsuru, Monitoring of rusting of stainless steels in marine atmospheres using electrochemical impedance technique corrosion, passivation, and anodic films, J. Electrochem. Soc. 153 (2006) B278-B282. 

Gonzalez et al. [43] and Lopez et al. [44] investigated the atmospheric corrosion of aluminum with different layers of anodic films in eleven different environments with estimated levels of salinity. Electrochemical corrosion techniques and electrochemical impedance spectroscopy were used to estimate the corrosion rates. The results indicated that at critical levels of anodic film thicknesses, the aluminum could be protected for a long time even when exposed to high levels of salinity. 

Some commercially available electrochemical impedance test systems have the ability to measure not only the overall impedance of a complete electrochemical cell, but also the impedance contribution of various component parts of the cell allowing, for example, direct comparison of different anode or cathode materials in a battery. Multielectrode measurement techniques may also be used to investigate individual cells in a battery or fuel cell stack (Figures 3.2.6 and 3.2.7). 

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