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Biomaterials are engineered to develop an interaction with living cells for therapeutic and diagnostic purposes. The last decade reported a tremendously rising shift in the requirement for miniaturized biomedical implants exhibiting high precision and comprising various biomaterials such as non-biodegradable titanium (Ti) alloys and biodegradable magnesium (Mg) alloys. The excellent mechanical properties and lightweight characteristics of Mg AZ91D alloy make it an emerging material for biomedical applications. In this regard, micro-electric discharge machining (µEDM) is an excellent method that can be used to make micro-components with high dimensional accuracy. In the present research, attempts were made to improve the µEDM capabilities by using cryogenically-treated copper (CTCTE) and brass tool electrodes (CTBTE) amid machining of biodegradable Mg AZ91D alloy, followed by their comparison with a pair of untreated copper (UCTE) and brass tool electrodes (UBTE) in terms of minimum machining-time and dimensional-irregularity. To investigate the possible modification on the surfaces achieved with minimum machining-time and dimensional-irregularity, the morphology, chemistry, micro-hardness, corrosion resistance, topography, and wettability of these surfaces were further examined. The surface produced by CTCTE exhibited the minimum surface micro-cracks and craters, acceptable recast layer thickness (2.6 µm), 17.45% improved micro-hardness, satisfactory corrosion resistance, adequate surface roughness (Ra: 1.08 µm), and suitable hydrophobic behavior (contact angle: 119°), confirming improved biodegradation rate. Additionally, a comparative analysis among the tool electrodes revealed that cryogenically-treated tool electrodes outperformed the untreated ones. CTCTE-induced modification on the Mg AZ91D alloy surface suggests its suitability in biodegradable medical implant applications.

International audience; Carbon/silicon carbide composites are tested at surface temperature above 2000 K in a high-enthalpy nitrogen flow at 2000 Pa, generated by an inductively coupled Plasmatron. Their altered surface is analyzed using scanning electron microscopy. Comparisons with experiments in air plasma at similar heat flux and pressure conditions suggest that the sole presence of nitrogen prevents the occurrence of temperature jump effect observed for this class of materials in flows containing oxygen reactants. Optical emission spectroscopy measurements near the surface confirm a lower volatility for the material tested in nitrogen compared to air.

Electrodeposition from an environmentally friendly iron sulfate electrolyte with citric acid as carbon source has gained attention recently, because of excellent mechanical properties of the resulting Fe–C coatings with intentionally codeposited high-carbon concentrations. While being very attractive as protective coatings and sustainable alternatives for hard chrome coatings, comprehensive understanding of the coatings' chemical constitution including the type and location of carbon-containing phases is still lacking. The amount of codeposited carbon of up to about 0.8 wt.% significantly exceeds the solubility of carbon in ferrite, although carbon-free ferrite is the only unambiguously reported phase in as-deposited Fe–C coatings so far. In the present work, time-of-flight secondary ion mass spectrometry, X-ray photoelectron spectroscopy, and soft X-ray emission spectroscopy have been applied to identify the carbon-containing phases, which are present as minor secondary phases in the coatings but are known to have an important influence on the coatings' properties. Three carbon-containing phases could be distinguished, homogeneously distributed in the nanocrystalline ferrite base material. Iron acetates, amorphous carbon, and carbides were found in both as-deposited and annealed Fe–C coatings up to 300°C, but their fraction changes during postdeposition annealing.

The non-degradable metallic implants, such as bone screws, often act as the source of dysfunction and harmful corrosion products in the aqueous environment inside the human body. Many of these implants are fixed either temporarily or permanently into the human body, and therefore, both need to match tight tolerances with a remarkably finished surface to eradicate burrs or striations. In this regard, the new generation of degradable magnesium (Mg) alloy implants with excellent osseointegration and low elasticity (like that of human bone), minimizing stress shielding, have been identified as potential candidates to challenge surgical procedures reintervention. However, the biological response of an implant toward the cells in vivo can be predominantly regulated by modifying the surface chemistry, morphology, and corrosion characteristics. Powder or abrasive-mixed-micro-electric discharge machining (A-M-µ-EDM) is gaining attention for executing precision machining and achieving a simultaneous surface modification on micro-manufactured surfaces, suitable for clinical applications. Therefore, the present research aimed at improving the surface characteristics of Mg AZ31B alloy via an augmented performance of A-M-µ-EDM by adopting copper and brass-micro-electrodes (C-µ-E and B-µ-E) in association with distinct abrasive particle concentrations (APCs: 0, 1.5, 3, 4.5, and 6 g/l) of bioactive zinc abrasives. To enhance the A-M-µ-EDM capabilities, the experiments were designed with a one-variable-at-a-time (OVAT) strategy, and the trial runs were conducted using different combinations of µ-electrodes and APCs. The superior performance of A-M-µ-EDM was noticed with the fusion of C-µ-E and 3 g/l APC in terms of minimum machining time (MT) and dimensional deviation (DD). The additional outcomes of this work reported favorable improvements in surface morphology, chemistry, topography, wettability, microhardness, and corrosion resistance on the A-M-µ-EDMed sample of interest.

This work investigated the chemical and electrochemical mechanisms of localised corrosion triggered by CaS·xMgO·yAl2O3·TiN complex inclusions in high strength low alloy steel (HSLAS) under a simulated marine environment. Special focus was given to the role of the TiN portion of the inclusion on the initiation and growth of the corrosion pits. The thermodynamic process of pitting initiation was investigated by Gibbs free energy, Pourbaix diagram and first principle calculation. Localised corrosion is mainly induced by inclusions and triggered by dissolution of adjacent distorted matrix. Chemical dissolution of CaS portion in CaS·xMgO·yAl2O3·TiN complex inclusion creates an acidic aggressive environment that accelerates the further dissolution of inclusion and matrix. Galvanic coupling effect between TiN inclusion and matrix is directly verified. TiN covered with a TiO2 film acts as the cathodic phase in galvanic corrosion, although it has a lower Volta potential than the matrix. This is an unusual correlation with the scanning Kelvin probe force microscopy result, which has been explained for this special system.

water uptake in organic coatings. To this aim, we start from a physical model, where not only Fickian diffusion of water is taken into account but also the adsorption/desorption reaction of water on the polymer matrix. Starting from a number of important coating properties and crucial model parameters, derived from gravimetric and Fourier transform infrared (FTIR) measurements as the model input, the local water concentration over the coating thickness as a function of time is modelled for a polyethylene glycol diacrylate (PEGDA) coating. The modelled water concentration is then used to calculate virtual capacitance values which are evaluated against experimental capacitance values extracted from impedance measurements. The constraints of the FEM model and ORPEIS experiments and the discrepancies between them are critically discussed in order to carry out a meaningful model validation, eventually leading to model improvements.

Carbon nanofibers (CNFs) is a typical electrical loss material with strong permittivity that has been widely used in the field of electromagnetic shielding, attenuation, and reception. However, studies have demonstrated that the unstable anisotropic EM behavior exhibited by CNFs in the terahertz domain hinders its application in the tremendously high frequency domain. In this study, ZnO is used to perform surface modification of CNFs based on the sputtering method, which effectively eliminate the anisotropic EM behavior of CNFs at different irradiation angles in the sub-terahertz band. ZnO coated the surface of fiber wall comprehensively in the form of nano-scale. The results show that after the surface modification, the composite sample exhibits a stable isotropic EM response in the sub-terahertz band of 500-750 GHz. Also, in the frequency range of 551-563 GHz (bandwidth: 12 GHz), ZnO not only acts as a stabilizer, but also enhances the absorption performance of the original CNFs by 6%, which is up to 92%. In the frequency range of 660-690 GHz (bandwidth: 30 GHz), the composite sample and the pure CNFs sample have similar wave absorption performance with about 75%, the maximum difference is less than 5%, and the minimum is about 2.6%.

Materials and corrosion (2022). doi:10.1002/maco.202213140, Published by Wiley-VCH, Weinheim [u.a.]

Effect of bisulfite (HSO3-) on the stress corrosion cracking (SCC) behavior of 7050-T7451 aluminum alloy in the thin electrolyte layer environment in the presence of Cl- is investigated. Addition of HSO3- inhibits the corrosion initiation but promotes the corrosion propagation and hydrogen uptake. With a quantitative calculation, the HSO3- is demonstrated to significantly facilitate the synergistic effect between stress, corrosion, and hydrogen during the in-situ tensile test, resulting in the change of the SCC controlling step from corrosion-induced hydrogen to mechanical-electrochemical-hydrogen interactions. The buffer effect of HSO3- plays a dominant role in the HSO3--induced acceleration of the SCC degradation.

Interest in deep eutectic solvents (DESs), particularly for electrochemical applications, has boomed in the past decade because they are more versatile than conventional electrolyte solutions and are low cost, renewable, and non-toxic. The molecular scale lateral nanostructures as a function of potential at the solid–liquid interface—critical design parameters for the use of DESs as electrochemical solvents—are yet to be revealed. In this work, in situ amplitude modulated atomic force microscopy complemented by molecular dynamics simulations is used to probe the Stern and near-surface layers of the archetypal and by far most studied DES, 1:2 choline chloride:urea (reline), at the highly orientated pyrolytic graphite surface as a function of potential, to reveal highly ordered lateral nanostructures with unprecedented molecular resolution. This detail allows identification of choline, chloride, and urea in the Stern layer on graphite, and in some cases their orientations. Images obtained after the potential isswitched from negative to positive show the dynamics of the Stern layer response, revealing that several minutes are required to reach equilibrium. These results provide valuable insight into the nanostructure and dynamics of DESs at the solid–liquid interface, with implications for the rational design of DESs for interfacial applications.

In this work, the corrosion susceptibility of powder coated Al6060 alloys with increasing Cu and Zn content is evaluated in a benchmark test. Although higher Cu and Zn limits would enable the industry to increase the use of end-of-life scrap and thus produce eco-friendlier aluminium profiles, such alloys are often disregarded due to concerns of corrosion, especially filiform corrosion. Our results suggest that this concern is ungrounded as long as typical quality specifications for the pre-treatment and coating process are followed and the alloy composition is kept within the limits of the European norm AW6060. Furthermore, we point out that the variation of the results due to processing at different coating production lines is larger than the difference between alloys of different Cu and Zn contents.

The effect of hot stamping on the corrosion properties of boron-manganese 22MnB5 steel coated with hot-dip aluminum-silicon was evaluated under severe conditions by a continuous salt spray test (SST). The corrosion mechanism changed from localized to generalized, as cathodic precipitates were not present after hot stamping. Intrinsic defects in press-hardened steel samples were the reason for severe damage in both metallic coating and steel substrate under SST conditions. The red rust formed at the top surface, characterized as different iron-based compounds, is due to both the iron diffusion from the steel substrate toward the surface and the corrosion of the steel substrate.

Vapor-phase film deposition of metal-organic frameworks (MOFs) would facilitate the integration of these materials into electronic devices. We studied the vapor-phase layer-by-layer deposition of zeolitic imidazolate framework 8 (ZIF-8) by consecutive, self-saturating reactions of diethyl zinc, water, and 2-methylimidazole on a substrate. Two approaches were compared: (1) Direct ZIF-8 "molecular layer deposition" (MLD), which enables a nanometer-resolution thickness control and employs only self-saturating reactions, resulting in smooth films that are crystalline as deposited, and (2) two-step ZIF-8 MLD, in which crystallization occurs during a postdeposition treatment with additional linker vapor. The latter approach resulted in a reduced deposition time and an improved MOF quality, i.e., increased crystallinity and probe molecule uptake, although the smoothness and thickness control were partially lost. Both approaches were developed in a modified atomic layer deposition reactor to ensure cleanroom compatibility.

The capabilities of scanning Kelvin probe force microscopy (SKPFM) to directly measure local Volta potential differences with relatively high spatial resolution, has made it a very popular technique to assess the relative nobility of intermetallic phases and therefore to understand corrosion susceptibility and microgalvanic corrosion activity in several alloys. However, the direct correlation between galvanic corrosion activity and Volta potential differences measured in air is not straightforward. Several factors, which can easily go unnoticed, can directly affect the potential values measured by SKPFM, hence compromising their validity and relevance in explaining certain galvanic corrosion activities. Several recent studies presenting conflicting/varied results or failing to properly interpret/discuss the obtained data can be found. This work discusses specific factors that can compromise the validity of SKPFM measurements and/or the understanding acquired from them. It presents a discussion on the SKPFM working principle, the basics of galvanic corrosion, and the relevant terminology around these topics, emphasising the possible correlations between them, with the intention of increasing comprehension of SKPFM-based micro-galvanic corrosion studies. A summary of best recommended practices is presented, aiming at standardizing the use of the SKPFM technique and the representation of the data, and to ensure consistency of the results.

This work provides a data-oriented overview of the rapidly growing research field covering machine learning (ML) applied to predicting electrochemical corrosion. Our main aim was to determine which ML models have been applied and how well they performed depending on the corrosion topic considered. From an extensive review of corrosion articles presenting comparable performance metrics, a ‘Machine learning for corrosion database’ was created, guiding corrosion experts and model developers in their applications of ML to corrosion. Potential research gaps and recommendations are discussed, and a broad perspective for future research paths is provided.

International audience; The behavior of carbon/silicon carbide composites at very high temperatures is investigated in an inductively-coupled plasma generator that simulates atmospheric re-entry aerothermal conditions for space vehicles. Samples exposed to heat fluxes exceeding 1.2 MW/m2 and low pressures of 2000–6000 Pa show a spontaneous jump in surface temperature near 2100 K, rapidly leading to temperatures above 2400 K. Under these conditions the silicon carbide coating at the samples’ surface is entirely eroded and the bare carbon fibers of the substrate are left exposed to the incoming flow. The material loses nearly half of its mass and is no longer reusable. The temperature jump phenomenon is described by means of infrared temperature measurements and real time visible recordings of the surface. Space- and time-resolved optical emission spectroscopy and scanning electron microscopy analysis of the samples are used to discuss and explain the chemical processes occurring at the surface. Jump conditions are compared to the passive and active oxidation regimes for carbon/silicon carbides, showing that such a sudden temperature increase occurs at conditions beyond active oxidation and cannot be attributed to the passive/active transition itself.

Electrorefining is the process of choice to purify several metals, among which is copper. A crucial process parameter in electrorefining, and electroplating in general, is the additive activity. Several additives are introduced to the electrolyte to ensure a morphological smooth copper deposit. Thiourea is a crucial but complex additive used in copper electrorefining, it is known to degenerate and both the reaction product as thiourea itself can complex with the copper ions. Unfortunately, time dependent additive studies and mechanistic knowledge of the effect of aged electrolyte on the cathodic part of the electrorefining process are scarce. In this work, operando Odd Random Phase Electrochemical Impedance Spectroscopy (ORP-EIS) is used to study the electrochemistry of a copper plating system containing industrial copper concentrations. The approach applied enables the investigation of the time-varying effect of additives, in this case thiourea and chlorides, assisting the electroplating of copper.

Composites formed by a metal–organic framework (MOF) and an ionic liquid (IL) are potentially interesting materials for applications ranging from gas separation to electrochemical devices. Consequently, there is a need for robust and low-cost preparation procedures that are compatible with the desired applications. We herein report a solvent-free, one-step, and vapor-based ship-in-bottle synthesis of the IL@MOF composite 1-butyl-3-methylimidazolium bromide@ZIF-8 in powder and thin film forms. In this approach, volatile IL precursors evaporate and subsequently adsorb and react within the MOF cages to form the IL.

Two-dimensional (2D) allotropes of tellurium (Te), recently coined as tellurene, are currently an emerging topic of materials research due to the theoretically predicted exotic properties of Te in its ultrathin form and at the single atomic layer limit. However, a prerequisite for the production of such new and single elemental 2D materials is the development of simple and robust fabrication methods. In the present work, we report three different 2D superstructures of Te on Au(111) surfaces by following an alternative experimental deposition approach. We have investigated the superstructures using low-temperature scanning tunneling microscopy and spectroscopy, Auger electron spectroscopy (AES), and field emission AES. Three superstructures (13 × 13, 8 × 4, and √11 × √11) of 2D Te are observed in our experiments, and the formation of these superstructures is accompanied by the lifting of the characteristic 23 × √3 surface reconstruction of the Au(111) surface. Scanning tunneling spectroscopy reveals a strong dependence of the local electronic properties on the structural arrangement of the Te atoms on the Au(111) support, and we observe superstructure-dependent electronic resonances around the Fermi level and below the Au(111) conduction band. In addition to the appearance of the new electronic resonances, the emergence of band gaps with a p-type charge character has been evidenced for two out of three Te superstructures (13 × 13 and √11 × √11) on the Au(111) support.

This work aims at the elucidation of the interfacial interactions established between an epoxy-amine coating and hot-dip galvanized (HDG) steel. The influence of the Zr-based conversion treatment of the substrate and the use of the Cu(II) additive on interfacial bonding is studied. To this purpose, an amine-functionalized molecule – diethylenetriamine (DETA) – is adsorbed. The complex multi-metal oxide surface of the Cu-modified Zr-based converted substrate is decomposed in derivative (simpler) systems. The resulting DETA-adsorbed model and multi-metal surfaces are investigated by X-ray photo-electron spectroscopy (XPS), and by examination of the N 1s peak, the interfacial bond density is determined. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) is performed to discriminate between the different metal oxide contributions present on the substrate surface. Preferential adsorption of the DETA molecule on the zinc atoms is found on converted substrates. The interfacial bonding with the Cu cationic sites introduced by the copper additive is proven.

This work analyses the microstructural defects and the corrosion behaviour of 316L stainless steel clads deposited by laser metal deposition on wrought conventional material, which is a highly relevant system for repair applications. The different defects and microstructural features found in these systems were identified and analysed from a perspective relevant to the corrosion performance of these materials. The role of these features and defects on the corrosion process was evaluated by exposure of the samples to corrosive media and further examination of the corrosion morphology. The heat-affected zone, located on the wrought base material in close vicinity of the deposited clad, was identified to be the primary contributor to the corrosion activity of the system due to the large depletion of alloying elements in this region, which significantly decreased its pitting resistance. Alongside the heat-affected zones, relatively small (

The growth of dendrites on lithium metal electrodes is problematic because it causes irreversible capacity loss and safety hazards. Localised high-concentration electrolytes (LHCEs) can form a mechanically stable solid-electrolyte interphase and prevent uneven growth of lithium metal. However, the optimal physicochemical properties of LHCEs have not been clearly determined which limits the choice to fluorinated non-solvating cosolvents (FNSCs). Also, FNSCs in LHCEs raise environmental concerns, are costly, and may cause low cathodic stability owing to their low lowest unoccupied molecular orbital level, leading to unsatisfactory cycle life. Here, we spectroscopically measured the Li+ solvation ability and miscibility of candidate non-fluorinated non-solvating cosolvents (NFNSCs) and identified the suitable physicochemical properties for non-solvating cosolvents. Using our design principle, we proposed NFNSCs that deliver a coulombic efficiency up to 99.0% over 1400 cycles. NMR spectra revealed that the designed NFNSCs were highly stable in electrolytes during extended cycles. In addition, solvation structure analysis by Raman spectroscopy and theoretical calculation of Li+ binding energy suggested that the low ability of these NFNSCs to solvate Li+ originates from the aromatic ring that allows delocalisation of electron pairs on the oxygen atom.

This research unravels the formation mechanism of a hybrid conversion treatment including the well-established Zr conversion coating with a silane-based organic additive and Cu-based inorganic additive. The deposition mechanism of this coating was investigated on the thermal oxide film of Advanced High Strength Stainless Steels (AHSSS). This coating has been characterized using advanced surface analytical techniques such as XPS, FEG-AES, GDOES, and ToF-SIMS. The results showed that the simultaneous presence of these two additives results in the formation of a donor-acceptor complex between amine groups and Cu ions. The final coating contains Cu oxide together with a Cu-aminosilane complex, Zr oxide deposited mainly around Cu oxide and the aminosilane layer on the outer surface.

The synthesis of novel, renewable lignin-based protective films with anticorrosive properties is presented in this work. Thermosetting films are prepared by means of tandem UV-initiated thiol-yne "click" synthesis and Claisen rearrangement strategy. These films contain high lignin loading, 46-61%, originating from a nickel-catalyzed birch wood reductive catalytic fractionation (RCF) process. Lignin fractions with varying monomer content are compared before resins preparation, namely a mixture of monomers and oligomers without fractionation, or after fractionation via extraction and membrane separation. This study aims to determine if the separation of lignin monomers and oligomers is necessary for the application as a thermosetting resin. The resulting films exhibit remarkable adhesion to a metal surface and excellent solvent resistance, even after exposure to a corrosive environment. Moreover, those films show superior barrier properties, studied with odd random phase electrochemical impedance spectroscopy (ORP EIS). After 21 days of exposure, the examined films still show impressive high corrosion protection with the low-frequency impedance approximate to 10(10) omega cm(2) and capacitive behavior. This work demonstrates an interesting proof-of-concept where laborious, costly, and energy-intensive separation of the depolymerized lignin mixture of monomers and oligomers is not necessary for the successful resin synthesis with excellent properties using the applied synthetic strategy.

A novel molecularly imprinted monolithic (MIM) column was designed and fabricated using the epitope approach, and was used for the selective capillary microextraction (CME) of the neuropeptides neurotensin (NT) and neuromedin N (NmN). The MIMs were synthesized in a capillary by thermally initiated polymerization of the functional monomer (methacrylic acid (MAA)), in the presence of a dummy template (Pro-Tyr-Ile-Leu (PYIL)), a crosslinker and porogens. The resulting monoliths were characterized by scanning electron microscopy, pore size distribution measurement, and Fourier transform infrared spectroscopy. Different synthesis conditions of the MIM column were investigated. The parameters affecting the MIM-CME performance, including loading, washing and elution protocols, were optimized as well. The MIMs were used to enrich NT and NmN from human plasma prior to HPLC-UV analysis. The imprinted monolith showed an excellent maximum adsorption capacity of 245–711 mg mL−1 and selectivity (imprinting factor of 5.7–13.4) towards its target peptides. Low detection limits of 0.62 and 1.20 nM, and satisfactory recoveries (82.5–98.8%) were obtained for NT and NmN, respectively. The proposed MIM-CME/HPLC-UV method was found suitable to be used as an effective tool for the highly efficient and specific analysis of NT and NmN in human plasma samples.

In the production of hydrogen gas, the removal of hydrogen chloride (HCl) is of particular relevance for the chemical industry. Here we report the HCl removal performance of ZIF-8 metal organic framework demonstrated via fixed-bed (dynamic) measurements under process conditions. The measurements revealed an HCl removal capacity of 1.02 g/g, outperforming by far all traditional materials and other metal-organic framework previously tested. The ZIF-8, before and after the HCl contact, was characterized via SEM-EDX, XRD, TGA, ATR-FTIR, XPS and Raman spectroscopy. The results showed a dramatic change in textural, structural and chemical properties of ZIF-8 after HCl contact, where the MOF material undergoes a reaction and re-crystalizes into a salt complex.

Accurate surface temperature and recession measurements are crucial experimental data for plasma wind tunnel testing of ablative thermal protection materials. In this work we propose a novel methodology to reconstruct infrared temperature maps on 3D geometries undergoing surface recession. An optical calibration technique is used to extract 3D metric information from the 2D thermal images, thanks to a specific calibration target with control points. The evolution of the sample shape during the experiment is tracked from a side view, using a visual-range camera with dedicated image processing, and reconstructed in 3D under the assumption of axisymmetry. The surface temperature is projected on the time-varying 3D geometry from the calibrated thermograms. The technique is demonstrated on a graphite ablation experiment in air plasma. The reconstructed maps provide detailed multidimensional information about the transient temperature evolution, overcoming traditional approaches that are limited around the stagnation point. The technique allows to study ablation mechanisms with further detail, improving experimental data for material qualification and validation of simulation codes.

The Main Ethiopian Rift (MER) is a tectonically and magmatically active rift in the northern portion of the East African Rift System. The MER contains around 60 volcanoes with some evidence of activity in the Holocene. Large caldera-hosting silicic volcanoes are dotted along the rift floor, including some with evidence of explosive eruptions every few hundred years. The pre-eruptive storage conditions and magmatic evolution of most MER silicic volcanoes remain poorly understood. The Bora-Baricha-Tullu Moye is a Late Quaternary volcanic system in the MER, characterised by products of both explosive and effusive volcanic eruptions. The petrological and geochemical characteristics of the volcanic products are investigated. The bulk rock compositions vary from basalt to comendite and pantellerite, and the chemical variability can largely be explained by fractional crystallisation processes starting from a transitional basaltic parent magma with minor crustal assimilation and magma mixing. The comendite and pantellerite deposits systematically show variation in glass and mineral compositions along stratigraphy. The combination of thermometry and barometry modelling suggests that the basaltic magma is stored at high temperature (1070-1190 °C) at mid-crustal level (~7-29 km). The peralkaline rhyolite melts are stored at a lower temperature (i.e., 805-900 °C for comendite and 700-765 °C for pantellerite) at shallow crustal levels (~4 km). Stratigraphic evidence in combination with the pre-eruptive storage conditions further elucidates that these shallow peralkaline magmatic reservoirs temporally evolve to cooler storage.&nbsp, The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)

As the fabrication scale of graphene continues to expand, the limitations of existing mass characterization techniques such as Raman spectroscopy, AFM, and other microscopic characterization techniques for large-scale homogeneity characterization of graphene films become more and more prominent. Although the line-shaped defects (primarily grain boundaries and folds) distributed on the graphene film can be observed using the above techniques, it is difficult to comprehensively evaluate their distribution state on the entire film surface using these instruments. Based on this background, the author’s group has been aiming at the above problems by combining terahertz vector network analysis technology with the detection of large-area homogeneity of graphene films and quantitative characterization of line-shaped defects on the film surface, to explore a quality inspection technology that can be used in the production line of graphene films. The results demonstrate that the terahertz transverse electric (TE) wave is extremely sensitive to the variation of local thickness and electrical conductivity, which can be used in the homogeneity testing for the graphene; distributed line-shaped defects on graphene surface can exhibit anisotropic EM behavior with respect to THz TE waves, which can be exploited to identify the defect distribution states.

Metal additive manufacturing (AM) refers to any process of making 3D metal parts layer-upon layer via the interaction between a heating source and feeding material from a digital design model. The rapid heating and cooling attributes inherent to such an AM process result in het erogeneous microstructures and the accumulation of internal stresses. Post-processing heat treatment is often needed to modify the microstructure and/or alleviate residual stresses to achieve properties comparable or superior to those of the conventionally manufactured (CM) counterparts. However, the optimal heat treatment conditions remain to be defined for the ma jority of AM alloys and are becoming another topical issue of AM research due to its industrial importance. Existing heat treatment standards for CM metals and alloys are not specifically designed for AM parts and may differ in many cases depending on the initial microstructures and desired properties for specific applications. The purpose of this paper is to critically review current knowledge and discuss the influence of post-AM heat treatment on microstructure, me chanical properties, and corrosion behavior of the major categories of AM metals including steel, Ni-based superalloys, Al alloys, Ti alloys, and high entropy alloys. This review clarifies significant differences between heat treating AM metals and their CM counterparts. The major sources of differences include microstructural heterogeneity, internal defects, and residual stresses. Under standing the influence of such differences will benefit industry by achieving AM metals with consistent and superior balanced performance compared to as-built AM and CM metals.

In this work, the separate diffusion of water and ions through a polyethylene glycol diacrylate (PEGDA) coating was characterized using an integrated spectro-electrochemical technique. The ions ingress front position profile along the thickness of the coating was derived from fitting odd random phase electrochemical impedance spectroscopy (ORP-EIS) data using a physically relevant electrochemical equivalent circuit (EEC). The arrival time of the ions at the coating/metal oxide buried interface obtained from EEC and rapid uptake of water was verified using in situ attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR) measurements in Kretschmann geometry integrated in the ORP-EIS set-up.

Atmospheric corrosion of metals is the most common type of corrosion which has a significant impact on the environment and operational safety in various situations of everyday life. Some of the common examples can be observed in land, water and air transportation systems, electronic circuit boards, urban and offshore infrastructures. The dew drops formed on metal surface due to condensation of atmospheric moisture facilitates corrosion as an electrolyte. The corrosion mechanisms under these droplets are different from classically known bulk electrolyte corrosion. Due to thin and non-uniform geometric thickness of the droplet electrolyte, the atmospheric oxygen requires a shorter diffusion path to reach the metal surface. The corrosion under a droplet is driven by the depletion of oxygen in the center of the droplet compared to the edge, known as differential aeration. In case of a larger droplet, differential aeration leads to preferential cathodic activity at the edge and is controlled by the droplet geometry. Whereas, for a smaller droplet, the oxygen concentration remains uniform and hence cathodic activity is not controlled by droplet geometry. The geometry of condensed droplets varies dynamically with changing environmental parameters, influencing corrosion mechanisms as the droplets evolve in size. In this review, various modelling approaches used to simulate the corrosion under droplet electrolytes are presented. In the efforts of developing a comprehensive model to estimate corrosion rates, it has been noted from this review that the influence of geometric evolution of the droplet due to condensation/evaporation processes on corrosion mechanisms are yet to be modelled. Dynamically varying external factors like environmental temperature, relative humidity, presence of hygroscopic salts and pollutants influence the evolution of droplet electrolyte, making it a complex phenomenon to investigate. Therefore, an overview of available dropwise condensation and evaporation models which describes the formation and the evolution of droplet geometry are also presented from an atmospheric corrosion viewpoint.

Electrochemical machining (ECM) and electropolishing are examples of anodic dissolution used in a wide variety of applications. Proper simulations of ECM require the establishment of a so‐called gel layer of liquid metal salt, responsible for the depletion of water close to the surface such that the oxygen evolution is reduced. However, this effect is neglected in many simulation efforts, although it is significant to improve the accuracy of the machining process. Some authors consider this effect by an engineered “water‐repelling” function that depends on the local metal ion concentration. As an alternative, we discuss the theoretical description and the implementation of modified Poisson–Nernst–Planck equations taking into account expressions in which each ion has its own maximum concentration and corresponding steric limit. We investigate a basic system of water, sodium chloride, and iron ions. Simulations pending on the local metal ion concentration for current densities show that the modified model works; steric effects become important for large current densities and the formation of a resistive gel layer is responsible for the reduction of water at the electrode. We observe that the electrostatic potential resulting from space charge effects is not affected by implementing the different species sizes. Further research is needed to explore the applicability of industrial simulation tools.

Many papers dealing with the surface analysis of plasma polymers or plasma-modified polymers report the use of X-ray photoelectron spectroscopy (XPS) to quantify the surface composition. However, most of the time, quantification is performed using software that includes an equation based on the assumption that the sample is homogeneous in composition. However, for plasma-treated samples, this is often not the case. The usual analysis of XPS spectra does not allow the exact quantification in the case of an inhomogeneous sample. In this paper, we show that it is possible to obtain a depth profile of the composition, and a more accurate surface composition by using another mathematical approach for surface quantification, being QUASES Tougaard.

High voltage cathodes suffer from degradation phenomena that are challenging to be observed and identified during cell operation. Dense and smooth sputtered thin films electrodes with absence of binders and conductive additives allow a direct study of the active material upon Li insertion and extraction at surface and bulk. Using an operando spectroscopic ellipsometry set-up combined with a customized electrochemical-optical cell (EC-SE), the evolution of the optical absorption and thickness of LiMn2O4 and LiNi0.5Mn1.5O4 thin-film electrodes was monitored upon cycling. Mixed Mn3+/4+ valence in the electrodes and evident layer dissolution associated to Transition Metal (TM) dissolution in the non-aqueous electrolyte at the applied polarization potentials was observed. Our results reaffirm EC-SE as a convenient method to study degradation phenomena in cobalt-free transition metal oxide electrodes.

Equilibria evolving over time, also called trends, are often present in ongoing measurements of real-life systems. These trends are considered as disturbances when computing the Best Linear Time-varying Approximation (BLTVA) of the system. Current techniques for dealing with trends in BLTVA measurements consist of modelling the trend with a finite number of basis functions. However, in measurements with dominant trends, the trend cannot always be captured well enough by this set of basis functions, and, hence, the uncertainty on the BLTVA increases. As a consequence, one looses low frequency information. In this paper, the state-of-the-art method for estimating the BLTVA is extended by removing the trend with a differencing operator. It is shown that with this novel technique, low frequency information becomes more visible. Moreover, the novel method decreases the variance on the BLTVA, and allows to measure fewer periods. Hence, the novel technique improves the route for treating arbitrary out-of-equilibrium, or also called operando, measurements. As an illustration, it is applied to operando time-varying impedance measurements of three electrochemical processes: the charging of a Li-ion battery cell, the electrorefining of copper and the anodising of aluminium.

Electrochemical impedance spectroscopy (EIS) is a versatile technique to characterize electrochemical systems satisfying causality, linearity and stationarity requirements. Odd Random Phase multisine EIS (ORP-EIS) can measure time-varying impedances for non-stationary processes. In this work, operando ORP-EIS is introduced to monitor the anodizing of aluminum, which is a nonlinear and non-stationary process, by superimposing a multisine AC perturbation signal on the anodizing DC potential. Results show that the multisine signal does not disturb the growth of the oxide film. Moreover, this technique makes it possible to follow the growth of the barrier oxide layer and provides an opportunity to investigate processes like ion adsorption, ion incorporation and ion movements through the oxide layer during anodizing. These processes cannot be studied by conventional EIS.

During atmospheric entry, micrometeorites experience variable degrees of (i) evaporation due to gas drag heating and (ii) mixing with atmospheric oxygen. Evaporation affects the physical properties and chemical and isotopic compositions of fully melted cosmic spherules (CSs). Oxygen isotope ratios of pristine micrometeorites are commonly used to relate these particles to their appropriate parent bodies. However, the degree of mixing with atmospheric oxygen and isotope fractionation by evaporation in CSs generally remains unclear, leading to uncertainties in their initial oxygen isotope ratios, which in turn complicates the precursor body identification. Previously, several studies have estimated the degree of evaporation based on contents of major refractory elements Ca and Al in combination with Fe/Si atomic ratios. This now commonly adopted chemical classification system has not yet been assessed with O and Fe isotope variability. As evaporation leads to both isotope and chemical fractionation, it is imperative to verify whether the predicted amounts of evaporation based on isotopic and chemical proxies converge.Here, we measure the major and trace element compositions of 57 chondritic (mostly vitreous) CSs, along with their Fe isotope ratios. The δ56Fe isotope and chemical (K, Zn, Na or CaO and Al2O3 concentrations) fractionation in these particles show no correlation. This can be interpreted in two ways: (i) separate processes govern chemical and isotope fractionation or (ii) the selected proxies for isotope and/or chemical fractionation are inadequate. Because the initial Fe isotope ratios of chondrites display limited variation (0.005 ± 0.008‰ δ56Fe), Fe isotope ratios in CSs are assumed to only have changed through evaporation. At the same time, the chemical compositions of CSs show larger variability, so the CSs are thus often not chemically representative of their precursor bodies.As oxygen isotope ratios are commonly used to identify the precursor bodies of (micro)meteorites, triple oxygen isotope ratios are measured in 37 of the 57 CSs. Based on the relationship between δ57Fe and δ18O, the effect of evaporation on the O isotope ratios can be corrected, which allows for a more precise precursor body reconstruction. Via this method, two 16O-poor spherules with greatly varying degrees of isotope fractionation (~1.0‰ and 29.1‰ δ56Fe, respectively) can be distinguished. Furthermore, it is observed that CSs that likely have an OC-like heritage all underwent the same degree of atmospheric mixing (~8‰ δ18O). These findings highlight the potential of including Fe isotope measurements to the regular methodologies applied to CS studies.

Summary: Formation of a decent solid-electrolyte interphase (SEI) is recognized as an approach to improve the performance of lithium-ion batteries. SEI is a passivation layer generated on the anode during the initial cycles. Characteristics of the graphite SEI depend on the operational parameters, state of the anode, and the content of the electrolyte. Introducing reduction-type additives to the carbonate electrolytes has been one of the most practiced methods to generate an effective SEI on carbonous anodes. To track the role of additives in SEI evolution, first, we have presented a general review on what is currently understood about the SEI formation processes and the impacting parameters. In the second step, the most reported methods to study and analyze the functionality of the SEI-forming additives are classified. As the third part, different reduction-type additives are categorized, and their performances are comparatively reviewed.

Electron paramagnetic resonance (EPR) spectroscopy is not considered a standard technique within the electrochemist's toolkit. It was used more frequently in electrocatalysis research from the 1960′s until the 1990′s to identify paramagnetic reaction intermediates and elucidate reaction mechanisms, but is less used nowadays. Since the 1990′s however, technological progress has made advanced EPR methods more readily available, which has allowed for more sensitive measurements and better identification of intermediate species. Furthermore, developments in additive manufacturing have made it easier and cheaper to construct specialized electrochemical cells for EPR research. This review aims to provide a critical overview of contemporary research combining electrocatalysis and EPR, and at the same time spark renewed interest in the combination of these two techniques. It is divided into three sections. Firstly, it covers the challenges involved with in situ cell design and gives an overview of recent cell designs. Next, a number of contemporary mechanistic and quantitative studies are reviewed to explore the possibilities of EPR spectroscopy. Finally, it covers advanced pulse EPR techniques and their (so far) limited use in electrocatalytic research.

The interactions of polymeric methylene diphenyl di-isocyanate (pMDI) and a model Fe–Cr alloy have been studied by X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS). Films of two different thicknesses have been investigated: one with an extremely thin pMDI layer in which the interfacial chemistry can be probed directly and a thicker one in which sputter profiling using cluster ions is necessary to expose the interface chemistry for direct analysis. Multivariate analysis (MVA), using principal component analysis (PCA) and nonnegative matrix factorisation (NMF), has been used to identify specific ions associated with the interfacial region of the ToF-SIMS sputter depth profile and chemical species from the XPS sputter depth profile. As an unsupervised method, this avoids an unconscious bias on the part of the analyst. Specific ions associated with pMDI interactions with both Fe and Cr allow the proposal of two complementary reaction mechanisms, supported by theXPS data. A range of cluster ions is used in this investigation, but the bulk of the work used argon clusters for the XPS depth profiles and Buckminster Fullerene projectiles for the ToF-SIMS analyses. To ensure that such data were directly comparable, the ToF-SIMS sputter profiles were repeated in a different system of the same type using argon cluster ions.

A Vector Network Analyzer (VNA) is an indispensable piece of equipment for the electromagnetic characterization of materials. With continuous development, the testing frequency band of the VNA has entered the terahertz domain. Previous studies have shown that carbon nanofibers (CNFs) prepared by the vapor method have excellent absorbing characteristics for both the microwave and the millimeter wave. This study is the first to characterize CNFs using a VNA in the 500–750 GHz band. The results show that CNFs with a random orientation distribution have an obvious polarization-sensitive absorption behavior in the 500–750 GHz band test, and this effect also causes a phenomenon of polarized reflection. As a comparison, the CNF sample was also tested in the W-band by the same test method. However, the result tested in the W-band showed a strong absorbing characteristic without any polarization response. The mechanism of the above phenomena was analyzed from the perspective of crystal growth and the principle of the antenna and polarizer. For further exploration and proof, CST Microwave Studio was used for the first time to model and simulate CNFs according to the actual parameters of the CNF sample.

Point defects play important and crucial roles in the design of high performance photocatalysts. We report on the electrochemical fabrication of black Ti−Mo-Ni−O nanotubes as a promising electrode material for solar-assisted water splitting. The ternary Ti−Mo-Ni−O catalyst was annealed in hydrogen atmosphere to induce point defects in the material to enhance its conductivity, charge carriers density, and performance. The effect of annealing duration on the performance of ternary Ti−Mo-Ni−O nanotube films was investigated. The hydrogen-annealed nanotubes showed enhanced optical characteristics in the visible spectrum, which can be related to the formation of defect states upon hydrogen annealing. The 10 h-annealed sample showed an exceptionally enhanced photocurrent density of ∼10 mA/cm2 with a remarkable open-circuit voltage of ∼−1.0 VAg/AgCl under AM 1.5G illumination. This improved photocurrent is in agreement with the obtained 75 % incident-photon-to-current-conversion-efficiency (IPCE), confirming the improved photoactivity of the hydrogen-treated mixed oxide nanotubes.

Empirical electrocatalyst research generally consists of the synthesis and experimental characterization of catalysts and the analysis of electrolysis products by conventional analytical techniques.In-situelectron paramagnetic resonance spectro-electrochemistry provides an evidence-based in-depth understanding of the formed intermediates and the reaction mechanism enabling the desired tuning of electrocatalysts. The use of this technique has been underexploited because of the opposite requirements they impose on the conventional setup. In this work, a versatile electrode with commercially available indium tin oxide on polyethylene terephthalate (PET) was constructed for the first time which can fit inside commonly used flat cells. It allows reproducible electrodeposition of catalytic material combined with sensitive radical detection, owing to its large surface area and minimal disruption to the resonator's Q-factor. Moreover, with a resistivity of 8-10 omega sq(-1), the surface potential of the thin semiconductor electrode within the resonator was well-controlled, allowing targeted radical production.

In this work, hot-dip galvanised steel wires were exposed in Belgium and Indonesia for 4.5 years and correlation of corrosion products formed on the exposed wires with their corrosion properties was studied. Corrosion products were identified with local Raman analysis and correlated with corrosion activity based on odd random phase electrochemical impedance spectroscopy and Tafel behaviour. Raman spectroscopy results confirmed that corrosion products formed in both atmospheric conditions differed either in quantity and/or in chemical nature, which indicated that ‘aged in Belgium’ and ‘aged in Indonesia’ wires did not have similar surface compositions. The comparison of the instantaneous corrosion behaviour of pristine and aged wires based on corrosion currents (polarisation curve) and impedance values in 0.1 M NaCl and 0.1 M Na2SO4 declared that aged in Belgium (AIB) and aged in Indonesia (AII) wires exhibited different corrosion behaviour, which confirmed that corrosion products formed in the environments of the exposed wires were dominating their corrosion behaviour.

The molecular configuration and chemistry at the zinc/zinc oxide-polyester interface were studied by using two complementary spectroscopic techniques: attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR) and sum-frequency generation (SFG) spectroscopy. It was shown that ATR-FTIR should be considered as a (3D) interphase-sensitive technique with probing depths of 250-400 nm in the headgroup region (2000-1200 cm-1). On the other hand, SFG is known to be a (2D) interface-sensitive technique. The ATR-FTIR measurements showed that carboxylate groups are formed within the near-interface region of the polyester phase. SFG measurements showed that the carboxylic acid groups are stable at the polymer-zinc/zinc oxide interface. In addition, in situ ATR-FTIR and SFG measurements have been conducted when exposing the polyester-zinc/zinc oxide system to D2O. The exposure to D2O is observed to lead to an additional conversion of ester and carboxylic acid groups to carboxylate groups. The comparison of the SFG and ATR-FTIR measurements shows that this conversion occurs much slower at the polyester-zinc/zinc oxide interface than in the bulk of the polyester. Finally, the strengths and limitations as well as the complementarity of both techniques are discussed.

Organofunctional silanes are applied as coupling agents between organic coatings and low carbon steel substrates to promote adhesion. Although the metal oxide-silane interface plays an important role in the performance of the entire overlying coating system, it remains challenging to obtain a clear understanding of the interfacial molecular bonding mechanism and its influence on adhesion. In this work, time-of-flight secondary ion mass spectrometry is used to study interfacial interactions between aminopropyl triethoxysilane (APS) and low carbon steel. APS is shown to bond to the steel substrate through silanol steel and amine-steel interactions, and coatings are cured at varying temperatures to evaluate the influence of curing on these different types of bonding interactions. Unambiguous evidence for hydrogen bond interactions between APS silanol groups and steel surface hydroxyl groups is provided for the first time in this work through deuteration of the steel substrate and allows to tackle long-lasting doubts about the most wide-spread bonding theory that has been postulated for silane adsorption on metals.

Micrometeorites experience varying degrees of evaporation and mixing with atmospheric oxygen during atmospheric entry. Evaporation due to gas drag heating alters the physicochemical properties of fully melted cosmic spherules (CSs), including the size, chemical and isotopic compositions and is thus expressed in its chemical and isotopic signatures. However, the extent of evaporation and atmospheric mixing in CSs often remains unclear, leading to uncertainties in precursor body identification and statistics. Several studies have previously estimated the extent of evaporation based on the contents of major refractory elements Ca and Al in combination with the determined Fe/Si atomic ratios. Similarly, attempts have been made to design classification schemes based on isotopic variations. However, a full integration of any previously defined chemical classification schemes with the observed isotopic variability has not yet been successful. As evaporation can lead to both chemical and isotope fractionation, it is important to verify whether the estimated degrees of evaporation based on chemical and isotopic proxies converge. Here, we have analysed the major and trace element compositions of 57 chondritic (mostly V-type) CSs, along with their Fe isotope ratios. The chemical (Zn, Na, K or CaO and Al2O3 concentrations) and δ56Fe isotope fractionation measured in these particles show no correlation. The interpretation of these results is twofold: (i) isotopic and chemical fractionation are governed by distinct processes or (ii) the proxies selected for chemical and isotope fractionation are inadequate. While the initial Fe isotopic ratios of chondrites are constrained within a relatively narrow range (0.005 ± 0.008‰ δ56Fe), the chemical compositions of CSs display larger variability. Cosmic spherules are thus often not chemically representative of their precursor bodies, due to their small size. As oxygen isotopes are commonly used to refine the precursor bodies of meteorites, triple oxygen isotope ratios were measured in thirty-seven of the characterized CSs. Based on the relationship between δ18O and δ57Fe, the evaporation effect on the O isotope system can be calculated, which allows for a more accurate parent body determination. Using this correction method, two ‘Group 4’ spherules with strongly variable degrees of isotope fractionation (δ56Fe of ∼1.0‰ and 29.1‰, respectively) could be distinguished. Furthermore, it was observed that all CSs that probably have a OC-like heritage underwent roughly the same degree of atmospheric mixing (∼8‰ δ18O). This highlights the potential of including Fe isotope measurements to the regular methodologies applied to CS studies.