A global transition towards more sustainable, affordable and reliable energy systems is being stimulated by the Paris Agreement and the United Nation's 2030 Agenda for Sustainable Development. This poses a challenge for the corrosion industry, as building climate‐resilient energy systems and infrastructures brings with it a long‐term direction, so as a result the long‐term behaviour of structural materials (mainly metals and alloys) becomes a major prospect. With this in mind “Corrosion Challenges Towards a Sustainable Society” presents a series of cases showing the importance of corrosion protection of metals and alloys in the development of energy production to further understand the science of corrosion, and bring the need for research and the consequences of corrosion into public and political focus. This includes emphasis on the limitation of greenhouse gas emissions, on the lifetime of infrastructures, implants, cultural heritage artefacts, and a variety of other topics.

Adhesively-bonded titanium components enable new design concepts in lightweight engineering but often lack long-term joint durability and endurance. Major challenges are related to the fact that the titanium/adhesive interface is susceptible to environmental ageing which leads to interfacial deadhesion. In the present work, the issue is addressed from the standpoint of semiconducting properties of surface TiO2 films. Examination of surface treated, anodized cp-Ti has been conducted using electrochemical impedance spectroscopy (EIS). Semiconducting properties of titanium oxide films were derived from Mott-Schottky analysis whereas roller-peel tests were considered for joint strength assessment before and after accelerated ageing in climate chambers. The experimental study is complemented by a computational study on the adhesion force distribution during roller peel testing based on a cohesive zone FEM model. The studies show clear indication for a complex interaction between the adhesion contributing underlying physio-chemical mechanisms. Crucial insights into the electrochemistry at the respective interfaces and their relevance for joint design are provided.

The mechanical response of a commercial aluminum alloy, AA7085, was examined using slow strain rate testing in dry air and humid air at 70 degrees C. These tests and fractographic observations confirmed that the alloy suffered from hydrogen embrittlement when exposed to humid air. Crack initiation was studied in both environments to evaluate the effect of humidity on crack nucleation. Observations from both slow strain rate tests and constant displacement tests were compared. Specimens from slow strain rate testing were examined after fracture while constant displacement testing allowed periodic observations of the sample surface. Based on these observations, a mechanism for the crack initiation in humidity has been proposed for AA7085 that does not involve substantial contribution from anodic dissolution.

Rare earth ions are amongst the most promising new generation corrosion inhibitors. This communication describes conditions where, instead of inhibition, acceleration of corrosion occurs after rare earth salts are added to solution. The work was carried out mainly with the Fe-Zn galvanic couple and different rare earth salts, using electrochemical techniques such as galvanic current measurements, scanning vibrating electrode technique and linear sweep voltammetry (polarization curves). The increased activity in the couple is associated to an unexpected cathodic reaction that is observed after adding the salts to solution. The new reaction signifies supplementary oxidant species being reduced at the iron electrode (cathode), accelerating the oxidation of zinc (anode). The nature of this cathodic process is discussed. (C) The Author(s) 2019. Published by ECS.

The hydrogen environmentally-assisted cracking (HEAC) behaviour of new generation (new-gen) Al-Zn-Mg-Cu thick-plate alloys (AA7449, AA7085, and AA7037), under accelerated humid warm-air exposure, has been compared to the aerospace industry benchmark alloy AA7050 in over-aged T7x type tempers. Constant load time-to-failure and DCB crack growth tests have been performed at a relative humidity of 85 %, at 70 degrees C. It has been found that in constant load tests the failure time of the new generation alloys can be reduced by at least an order of magnitude and in some cases cracking was observed in only a few days at stress levels of 85 % of yield. Analysis of the failed fractured specimens has confirmed that the fracture behaviour is predominantly intergranular, and highly localised to high angle grain boundaries. The progression from surface initiation to selfpropagating cracks occurred much more rapidly in the new higher Zn content alloys, but with less prior surface chemical attack. In DCB v-K tests stage II crack growth rates were also found to be significantly higher (by a factor of 6-20 times) in the new-gen alloys and the K-1HEAC threshold stress intensity was less than half that for AA7050-T7651. Under long crack growth conditions, propagation thus required a higher mechanical driving force and crack growth stagnated more readily in the AA7050-T7651 benchmark material, compared to in the new generation alloys. The results have been discussed in the context of the potential influences of differences in the alloy's chemistries and microstructures.

This study focuses on the development of a physico-chemical model based on mechanistic and kinetics understanding of the corrosion process in galvanic couple Ti6Al4V-AA2024. Proposed model provides deeper insights at macro level for initiation and propagation of localized corrosion of AA2024 in galvanically coupled multimaterial assemblies. The model is able to reveal the localized corrosion, related to heterogeneity of AA2024 microstructure, including local pH changes, the deposition of the reaction products, and emphasizes the important role of AA2024 self-corrosion in galvanic assemblies. The validation of the developed model was performed using relevant data collected by advanced in situ localized techniques.

This study analyses the evolution of surface characteristics of two industrial high‐strength 7xxx aluminium alloys with a focus on alloy composition and environmental parameters. Based on storage and transport conditions of as‐machined products, the effect of humidity—as liquid and vapour phase—on the natural oxide layer has been studied. The evolution of the natural oxide layer has been analysed by scanning electron microscopy and X‐ray photoelectron spectroscopy. The growth behaviour of the surface layer is dominated by environmental conditions, while microgalvanic activity depends mainly on the alloys' chemical composition and differs significantly for tested alloys. Scanning transmission electron microscopy images demonstrated that the long‐term exposure at moderate temperatures affects the microstructure near the surface, which differs for the analysed alloy compositions. An anomalous precipitation of zinc‐rich particles at the surface and along the precipitate‐free zone is observed for the alloy with higher Zn/Mg ratio and lower Cu content.

Li-LDH sealing is accounted for being highly competitive to standard hot-water sealing as referred to reduced treatment temperature and higher corrosion protection efficiency.

Smallmatek – Small Materials and Technol Portugal. E-mail: diogo.mata@smallmatek.p Institute of Materials Research, Helmholtz 1, 21502 Geesthacht, Germany Departamento de Ciência de Materiales, Fa Complutense, 28040 Madrid, Spain Brunel – Centre for Advanced Solidicatio Uxbridge UB8 3PH, UK CICECO, Dep. Materials and Ceramic Eng Aveiro, Portugal Airbus Group Innovations, 81663 Munich, G Faculty of Engineering, Christian-Albrechts Kiel, Germany † Electronic supplementary informa 10.1039/c7ra05593e Cite this: RSC Adv., 2017, 7, 35357

Tartaric-Sulfuric Acid (TSA) anodization is state of the art technique used in aeronautics for improved corrosion protection of AA2024. The resulting anodic layer ensures normally a reasonable adhesion to the subsequent coating layers. However the barrier properties are normally not sufficient and pores in the anodic oxide have to be sealed. Moreover a strategy for incorporation of active inhibitors into the anodic layer has to be found after implemented restrictions for use of chromates.

Zn–Al LDH-NO3 was grown on TSA anodized surface of AA2024 aluminum alloy LDH-VOx was obtained from LDH-NO3via anionic exchange reaction The LDH-VOx layer confers remarkable active corrosion protection.

The self-healing polymer coatings containing organic corrosion inhibitors are intensively investigated as an alternative for highly toxic Cr(VI)-based systems. Protective self-healing coatings are realized by embedding "smart" containers, able to release a corrosion inhibitor under some specific conditions occurring when the corrosion process starts (e.g. on pH change) or upon a mechanical damage. In this study a system with the corrosion inhibitors (2-methylbenzothiazole (BT) and 2-mercaptobenzothiazole (MBT)) encapsulated inside the polyelectrolyte nanocapsules embedded in the water-based epoxy coatings is tested for its self-healing performance. The nanocontainers were prepared by the electrostatic adsorption of polyelectrolytes directly on the oil phase drops containing the inhibiting agent. The results for BT emulsion droplets and the mixture of BT and MBT encapsulated by docusate sodium salt/poly(diallyldimethylammonium chloride) (AOT/PDADMAC) and docusate sodium salt/poly(diallyldimethylammonium chloride)/poly(styrene sulfonate) (AOT/PDADMAC/PSS) surface complexes are presented.The X-ray Photoelectron Spectroscopy (XPS) was used to confirm the release of the inhibitor from the scratched coating. The influence of the nanocapsules on the barrier properties and self-healing performance of the epoxy coatings were tested by electrochemical impedance spectroscopy (EIS) in NaCl solution, the salt spray test (SST) according to ISO9227 and filiform corrosion test (FFT) according to EN ISO 3665. Potential blistering was rated according to EN ISO 4628-2. (C) 2015 Elsevier B.V. All rights reserved.

hot/wet conditions Beatriz Rico-Oller, Tobias Mertens, Max Kolb, Jürgen Wehr, Theo Hack, Mikhail Zheludkevich 1 Airbus Group, Airbus Group Innovations, Dept. Metallic Technologies & Surface Engineering, 81663 Munich/Germany, tel: +49 89 607 27982, email: beatriz.b.ricooller@airbus.com 2 Helmholtz-Zentrum Geesthacht, Institute of Materials Research, Dept. of Corrosion and Surface Technology,Max-Planck Str. 1, 21502 Geesthacht/Germany

An experimental setup was developed for the validation of a finite element model (FEM) for simulating galvanic corrosion occurring under very thin electrolyte for bi-material combination composed of aluminium AA2024 and carbon-fibre reinforced polymer (CFRP). The validation approach is explained and the results obtained are presented. The main outcomes of the model are electric current density and potential distribution on the electrode surface. Good agreement has been obtained between measured and modelled data. Further parameter studies are discussed to show the effect of different physical properties of the electrolyte on corrosion rates and total current changes in the materials involved. (C) 2013 Elsevier Ltd. All rights reserved.