Development of layer‐by‐layer assembled thin coatings on aluminium alloy AA2024‐T3 for high resolution studies of local corrosion processes

Abstract

The aim of this study is to develop nanometer‐thin epoxy‐based films on aluminium alloy AA2024‐T3 as a model coating system for high resolution corrosion studies. Spin coating was used for the layer‐by‐layer (LbL) deposition of poly‐(ethylenimine) (PEI) and poly([o‐cresyl glycidyl ether]‐co‐formaldehyde) (CNER) bilayers. The film chemistry and the cross‐linking process were characterized by means of Fourier‐transform infrared spectroscopy (FTIR). Ellipsometric data confirmed the linear increase of film thickness. The potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) results indicate the improvement of the film barrier properties with increasing film thickness. Mapping of the topography and the volta potential was performed by means of scanning Kelvin probe force microscopy (SKPFM). The results indicate the presence of a homogeneous film structure, while the intermetallic phases can still be identified below the coating. The SKPFM analysis confirmed that the model films are suitable for investigation of corrosion processes at the coating/metal interface.

In Situ Atomic Force Microscopy Analysis of the Corrosion Processes at the Buried Interface of an Epoxy‐like Model Organic Film and AA2024‐T3 Aluminum Alloy

“…The preparation and full characterization of the model film system has been presented and discussed in a previous publication. [ 9 ] The topographical image of the coated sample before the corrosion test is presented in Figure a. IMPs protrude from the polished sample surface, as they possess a higher hardness and thus a lower polishing rate relative to the matrix.…”

“…Afterwards, the sample was accelerated with 1000 rpm s −2 to the desired rotation speed of 3000 rpm, where it rotated for 40 s. Finally, the samples were cured at 80 °C for 10 min. The optimization of the coating procedure was described in detail in the study by Almalla et al [ 9 ]…”

Visualization of working electrode reactivity from an electrochromic counter electrode

“…Measuring local electrochemical reactivity of electrodes is highly important for fundamental understanding of the materials as well as engineering of electrochemical devices [1][2][3][4][5]. This is usually achieved by scanning electrochemical probe techniques, such as scanning electrochemical microscopy (SECM) and scanning electrochemical cell microscopy (SECCM) [6,7].…”