Local electrochemical investigation of copper patina

Abstract

The patination of copper is known for its complexity and heterogeneous formation. For a deeper investigation, a locally resolved surface analysis was considered. An exact determination of the accessed area and a potentiostatic control in a three-electrode configuration was reached with the use of the electrochemical microcell technique, which enables local electrochemical measurement such as local electrochemical impedance spectroscopy and cyclic voltammetry. Such a technique provides a unique way for performing the investigation of heterogeneities on electrode surfaces. The local electrochemical measurements on the artificially patinated surface have allowed distinguishing areas of different reactivity even when the analysis of the surface revealed a homogenous chemical composition of patina. Local measurements with the electrochemical microcell showed the presence of small defects on the patina layer that can be modelled by considering a hemispherical diffusion process at small active areas surrounded by larger less reactive domains.

A New methodology of Nondestructive Testing for Quantitative Evaluation of Sigma Phase in Duplex Stainless Steels

“…14,16 In a similar way, it is reported in the literature the use of microcells for the study of localized corrosion in metals and their alloys, the reduction of the area of analysis allows the comparison between microstructural characteristics and local electrochemical processes that could hardly be obtained in the study of global corrosion. 17,18,19 In addition, there is a gain in the quality of the signal obtained from the possibility of high rates of mass transport from the working electrode, reduction of capacitive currents and reduction of Ôhmic drop 20 .…”

Surface Analytical Methods Applied to Magnesium Corrosion

“…SDC remains versatile toward electrochemical techniques that can be performed locally such as potentiodynamic polarization or voltammetry to extract local kinetics through accurate corrosion modeling. The wide variety of electrochemical techniques also include local chronoamperometry that can probe ions released during the corrosion process , or even perform local modification of surfaces. , …”

“…SDC remains versatile toward electrochemical techniques that can be performed locally such as potentiodynamic polarization or voltammetry to extract local kinetics through accurate corrosion modeling. The wide variety of electrochemical techniques also include local chronoamperometry that can probe ions released during the corrosion process 57,60 or even perform local modification of surfaces. 61,62 There are several examples where effective removal of longrange coupling has been achieved in Mg corrosion, 12,30,63−65 including AZ91 Mg alloy, which presents heterogeneous microstructures (1−5 in Figure 4B).…”

Highly customisable scanning droplet cell microscopes using 3D-printing

“…Within the last 15 years various types of SDCMs such as flow-type SDCM (FT-SDCM) [4] and V-shaped SDCM [5] for electrochemical flowthrough experiments or photoelectrochemical SDCM (PE-SDCM) [6] for local photoelectrochemistry have been developed. Until now SDCM has been applied for example for high-throughput screening of thin film material libraries [7,8], microstructuring of surfaces [9], local anodisations for plastic electronics [10], direct writing of anodic oxides [11], localised measurements on bulk samples [12][13][14][15], impedance measurements on the microscale [16] and online monitoring of reaction products by connecting the output of a FT-SDCM to external analytics such as ICP-MS [17,18] or ICP-OES [19,20]. Essentially a FT-SDCM is a mobile electrochemical flow-through cell that can be easily moved to another spot on the sample.…”