Electrochemical impedance spectroscopy analysis of cold sprayed and arc sprayed aluminium coatings serviced in marine environment

Abstract

High velocity arc spraying and cold gas dynamic spraying were applied to prepare the aluminium coating, and electrochemical impedance spectroscopy measurement in combination with scanning electron microscopy analysis of corrosion surface and X-ray diffraction results of corrosion product were used to compare the corrosion behaviour of these two coatings. It was found that there was sparse and porous corrosion product covering on the surface of the arc sprayed aluminium coating through which the Cl 2 can penetrate into the inner coating interface. In contrast, the surface of the cold sprayed aluminium coating after immersion was less porous and tended to seal the pores in the coating. This kind of structure can obstruct the penetration of corrosion medium into the inner coating surface and reduce the corrosion rate to a certain extent. In addition, the diffusion impedance O was introduced in the electrochemical impedance spectroscopy modelling for the purpose of getting good fitting results.

Sacrificial Thermally Sprayed Aluminium Coatings for Marine Environments: A Review

“…Coatings that were prepared with 40-50 µm and 50-75 µm Al powders performed well, both under NaCl immersion and 11 years of atmospheric exposure [23]. A better performance of cold-sprayed Al coatings (attributed to their lower porosity level) than arc-sprayed coatings in natural seawater was observed by other researchers [8].…”

“…There is no UV radiation during cold spraying, so no special eye protection measures are needed. Moreover, coatings that are prepared by cold spray tend to have a lower level of porosity [8], as can be seen in Figure 3. There are two key factors that determine the performance of sacrificial coatings:…”

“…However, the selection of appropriate equivalent electrical circuit that explains the mechanism occurring in the system can be very difficult, especially in case of porous coatings, such as TSA. Nonetheless, some researchers have done EIS modelling to understand the corrosion behaviour of sacrificial coatings [8,23,31,37,[89][90][91].…”

Anticorrosion Properties of Zn–Al Composite Coating Prepared by Cold Spraying

“…Therefore, it is of great significance to effectively protect metal materials in the marine environment. The research on marine metal materials has also received extensive attention from scholars [1][2][3][4][5].…”

“…It is portable to the entire surface of offshore equipment and is also suitable for the surface of equipment of various bases. (2) The thermal effect on the substrate and the powder particles is negligible, and the oxidation, burning loss, phase transformation and tissue change of the spray powder can be avoided. Meanwhile, the coating of the heat sensitive material such as the nanometer amorphous material is obvious.…”