Surface modification of stainless steels: green technology for corrosion protection

Many methods of corrosion protection rely on toxic chemicals such as hexavalent chromium (Cr⁶⁺), which is the species responsible for protection in conversion coatings, anodizing baths and as a pigment in polymer coatings. Despite many attemps to replace Cr⁶⁺ and other harzardous chemicals in corrosion protection, very little progress has been made. Passive layers containing Ce and Mo have already been formed on materials such as A17075 and A12024, and their corrosion behaviour has been shown to improve by inhibition of both anodic and cathodic reaction. In this work the results of applying these coatings to SS304 and 316 will be presented. The layers were studied by electrochemical impedance spectroscopy (EIS), X-ray photo-electron spectroscopy (XPS), and the corrosion behaviour was followed by EIS and d.c. current methods.     

Corrosion and corrosion protection of support structures for offshore wind energy devices (OWEA)

The paper provides a review about the corrosion and corrosion protection of offshore wind energy devices (OWEA). Firstly, special features resulting from location and operation of OWEA are being discussed. Secondly, types of corrosion and corrosion phenomena are summarized in a systematic way. Finally, practical solutions to the corrosion protection of OWEA, including steel allowances, cathodic protection and coatings and linings, are discussed.     

Development of Slippery Liquid-Infused Porous Surface on AZ31 Mg Alloys for Corrosion Protection

The relatively poor corrosion resistance remarkably limits the wide applications of Mg alloys in practice, although they possess many attractive properties, like low density, high specific strength, and good biocompatibility. The formation of a protective coating can effectively suppress the corrosion. In this work, a slippery liquid-infused porous surface (SLIPS), with good surface hydrophobicity, stability, and self-healing property, was formed on AZ31 Mg alloys. The development of SLIPS requires suitable porous micro/nanostructures. Layered double hydroxide (LDH), with effective corrosion resistance for Mg alloys, was a good candidate to accommodate the liquid lubricant. Especially, different temperatures were applied to in situ form MgAl-LDH on AZ31 Mg alloys. The results showed that the temperature of 120 °C was the best condition for the SLIPS to provide good corrosion protection for Mg alloys, with the lowest corrosion current density of 3.19 × 10^-9 A cm⁻². In addition, the SLIPS performed well in the long-term immersion test and abrasion test. The AZ31 Mg alloys with superior corrosion resistance and good mechanical and chemical stability can be extensively applied in areas of automotive, electronics, and aerospace.     

Electrodeposition of cerium (III)-modified bis-[triethoxysilypropyl]tetra-sulphide films on AA2024-T3 (aluminum alloy) for corrosion protection

The doping of rare earth salts, like Ce(III), has shown to enhance the corrosion performance of silane films due to their self-healing behaviors. In the present paper, the Ce(III)-doped bis-[triethoxysilypropyl]tetrasulphide (BTESPT) films with higher corrosion resistance were prepared by electro-assisted technique. The films were investigated using electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), water contact angle measurements and Fourier transform reflection absorption IR (FTRA-IR). The results showed that both the cathodic deposition and cerium-doping can promote the formation of thicker and compacter silane films and enhance their protectiveness in the early stage of immersion in the corrosive media. However, it seems that the Ce(III)-doped BTESPT films prepared by electrodeposition lose their self-healing abilities after long-term immersion. The reason is still unclear, but might be attributed to the precipitation of Ce(III) oxides or hydroxides during the electrodeposition of doped silane films.