Uses of Scanning Electrochemical Microscopy (SECM) for the Characterization with Spatial and Chemical Resolution of Thin Surface Layers and Coating Systems Applied on Metals: A Review

Abstract

Scanning Electrochemical Microscopy (SECM) is increasingly used in the study and characterization of thin surface films as well as organic and inorganic coatings applied on metals for the collection of spatially- and chemically-resolved information on the localized reactions related to material degradation processes. The movement of a microelectrode (ME) in close proximity to the interface under study allows the application of various experimental procedures that can be classified into amperometric and potentiometric operations depending on either sensing faradaic currents or concentration distributions resulting from the corrosion process. Quantitative analysis can be performed using the ME signal, thus revealing different sample properties and/or the influence of the environment and experimental variables that can be observed on different length scales. In this way, identification of the earlier stages for localized corrosion initiation, the adsorption and formation of inhibitor layers, monitoring of water and specific ions uptake by intact polymeric coatings applied on metals for corrosion protection as well as lixiviation, and detection of coating swelling—which constitutes the earlier stages of blistering—have been successfully achieved. Unfortunately, despite these successful applications of SECM for the characterization of surface layers and coating systems applied on metallic materials, we often find in the scientific literature insufficient or even inadequate description of experimental conditions related to the reliability and reproducibility of SECM data for validation. This review focuses specifically on these features as a continuation of a previous review describing the applications of SECM in this field.

Scanning electrochemical microscopy for the differentiation of radical-induced degradation mechanisms in polymer electrolyte membranes

“…the through-plane proton conductivity. If a sufficient cathodic potential is applied at the SECM tip, the tip current should increase while approaching the membrane (positive feedback 28 ) due to the reduction of protons to hydrogen (Fig. 3 black curve).…”

Influence of aluminum nanoparticles in epoxy resin and epoxy coating for anticorrosion and antibacterial protection in pipeline industry

“…Although electrochemical techniques provide powerful tools for the study of interfacial reactions, conventional methods fall short in providing information about the electrochemical reactions occurring at the sample surface. 34 Therefore, in addition to the EIS measurement, a scanning electrochemical microscopy (SECM) analysis of the samples was made, which gives the surface a representation of the coating in different shades that correspond to the electrochemical activity of the surface during 30 days of exposure in a 3.5 wt% NaCl solution. In this study, ic-ac-SECM was used primarily to evaluate the effect of Al NP on the corrosion protection performance of epoxy resin and epoxy paint over gray cast iron in a 3.5% NaCl solution.…”

Crevice Corrosion Behavior of 201 Stainless Steel in NaCl Solutions with Different pH Values by In Situ Monitoring

“…Nowadays, more and more researchers pay attention to SECM [ 33 , 34 , 35 , 36 , 37 , 38 , 39 ] due to its high spatial resolution and versatility. The ultramicroelectrode (UME) (in micro-scale or nano-scale) combined with a 3D mobile platform permits it to capture micro morphological and chemical data in situ over the interface [ 40 , 41 , 42 , 43 , 44 , 45 ].…”