Concrete production requires the use of fresh water to achieve better hydration, strength and durability, with an estimated consumption of around 1.7 % of the world’s freshwater withdrawals. Although this percentage is small, concrete construction is mainly concentrated in urban areas, and this leads to regional freshwater scarcity because wastewater purification is costly. Thus, it is essential to explore other alternatives, such as using industrial waste brine, to solve the freshwater-scarcity problem.

This work investigated four different mortar mixtures, which were ordinary Portland cement (CemI), CemI with 8 wt% fly ash, CemI with 8 wt% silica fume and Portland cement type III (CemIII) with slag, mixed with 2.56 M NaCl synthetic-brine water at a water-to-binder ratio of 0.55. For each, a mixture without chloride was also made for comparison. Fresh properties and hardened properties were measured. The amount of chloride in hardened mortars was determined. The corrosion behaviors of three embedded carbon steels were monitored using the linear polarization resistance measurement.

Results showed that mortars containing chloride had a higher slump flow and higher air content than mortars without chloride. The presence of chloride in mortars had a tendency to reduce bending and compressive strength and increase porosity, except in CemIII with slag, which showed similar bending and compressive strength as well as porosity regardless of the presence of chloride. Mortars with silica fume and slag showed a higher chloride-binding capacity, reducing the amount of free chloride ions available to initiate corrosion in embedded carbon steels. Among all the mixtures, CemIII with slag showed a lower mass loss and corrosion rate of embedded carbon steel compared to CemI, even with the presence of chloride in the mortar.

This study supports the feasibility of using waste brine as a mixing liquidtogether with pozzolanic materials for producing sustainable mortar and reducing steel corrosion.

Chloride-induced corrosion damage of steel in concrete typically initiates as localized pitting, which may either repassivate or continue to grow and evolve into more widespread forms of damage. However, models developed to forecast corrosion damage generally neglect the early stages of pitting corrosion. This omission stems in part from the assumption that traditional carbon steel reinforcement rapidly transitions to more general corrosion, as well as from the limited understanding of the fundamental mechanisms governing pitting corrosion in concrete. Most durability forecasting models therefore rely on a chloride threshold to distinguish between the period before and after corrosion initiation, implicitly assuming that exceeding a critical chloride content leads to widespread corrosion activation. In contrast, this paper explores an alternative framework grounded in established concepts of pit stability that are commonly applied to immersed and atmospheric corrosion systems.

This work seeks to elucidate the mechanisms controlling pit growth of steel in concrete through a combination of experimental methods and physics-based computational modeling, with the goal of identifying conditions under which repassivation may occur. Artificial pit experiments are employed to investigate the influence of concrete configuration on pit stability and repassivation behavior. The steel–concrete interface is highly complex and heterogeneous, and two key concrete properties are expected to play dominant roles in pitting corrosion: its ability to act as a diffusion barrier and its capacity to buffer pH. The former is anticipated to promote stable pit growth, whereas the latter is expected to favor repassivation.

Acidic decontamination sludges are currently unsuitable for final disposal due to their low pH and high concentrations of organic and complexing species, which hinder their direct stabilization and long-term management. In this work, an acidic liquid waste is immobilized using two types of alkali-activated slag binders, namely BFS-C and BFS-S, and the performance of these systems is compared with that of a reference Portland cement binder (R). In parallel, three stainless steel grades are evaluated as candidate materials for waste-conditioning drums intended for the containment of the immobilized waste. Electrochemical corrosion parameters are determined in order to assess the corrosion behaviour of the metallic materials when exposed to the different binder matrices. The results indicate that the duplex stainless steels 1.4482 and 1.4462, together with the austenitic stainless steel 1.4404, exhibit a moderate apparent tendency to corrode in the alkali-activated slag environment. However, surface examinations show that sulfide phases inherently present in the slag significantly influence the electrochemical response of the system. This effect leads to an overestimation of the actual corrosion activity derived from electrochemical measurements. Once this interference is taken into account, the results demonstrate that all three stainless steel grades are compatible with alkali-activated slag matrices and can be considered suitable materials for the confinement and conditioning of acidic liquid wastes.

This study is about the investigation of metal dusting (MD) on the alloys developed for coating in the petrochemical environments. Metal dusting is a corrosion phenomenon, which occurs in different materials, e.g., nickel-based alloys, resulting in material attack at high temperatures (350-800°C), when the carbon activity is greater than one (a_C>1). Alloys containing higher chromium contents can form a protective chromium oxide (Cr₂O₃) layer to retard MD. Protective oxide layers on the alloys form protection throughout the MD reaction period. Characterisations were undertaken on Ni-Cr and Ni-Cr-X (X = Al, Nb and Ti) alloys under heat-treated environments. Alloy compositions previously predicted using first-principle calculations were experimentally produced by a vacuum arc melting process. Before MD exposure, the alloys were annealed at 1100°C in the muffle furnace, and then water-quenched (WQ) and furnace-cooled (FC). Manufactured materials were investigated by optical microscopy (OM), scanning electron microscopy (SEM), and X-ray diffraction (XRD). The binary Ni-Cr and ternary Ni-Cr-X (Al, Nb and Ti) alloys were successfully produced using a vacuum arc melting technique. There manufactured alloys had scale layers on the surface after heat treatment. The alloys after etching showed austenitic microstructures. Cross-section SEM-EDS analysis showed that the alloys had developed chromium- and aluminium-oxide (Cr₂O₃ and Al₂O₃) layers on the surface after heat treatment. XRD revealed a complete austenite phase in all the ternary alloys. Metal dusting exposures and characterisation will be undertaken in further studies.

Corrosion of structural metals presents a significant challenge to material durability, particularly for infrastructure exposed to chloride-rich environments. This study investigates the performance of a water-borne acrylic coating formulated as a sustainable alternative to traditional solvent-borne systems. Carbon steel, copper, and aluminium substrates were evaluated through an integrated framework combining electrochemical testing, tensile analysis, and finite-element method (FEM) simulations. Mechanical testing suggests that the coating helps mitigate the onset of surface pitting and associated mechanical degradation. FEM simulations, utilizing elastic-plastic constitutive laws in ANSYS and COMSOL, reproduced the observed stress–strain behaviors. These models provide a framework for analyzing stress redistribution in protected systems, showing more uniform von Mises stress fields compared to degraded, uncoated specimens. Surface characterization via SEM and EDS confirmed coating uniformity and limited crack propagation at the interface. This study demonstrates the potential of combining electrochemical resistance with numerical modeling to assist in the service-life assessment of coated metallic infrastructure. Comprehensive electrochemical analyses, including Open-Circuit Potential (OCP) and Electrochemical Impedance Spectroscopy (EIS), were conducted in a 3.5 wt.% NaCl solution to simulate aggressive marine conditions. Under these controlled conditions, the coating demonstrated high barrier performance, with calculated inhibition efficiencies reaching 99.9% for carbon steel and aluminium. Complementary weight-loss measurements indicated a substantial reduction in corrosion rates, supporting the electrochemical data.

Corrosion of stainless steel in chloride-containing environments remains a critical challenge for industrial applications, particularly in marine, chemical processing, and oil and gas systems, necessitating durable protection strategies. In this study, the corrosion behavior of AISI SS316 in 3.5 wt.% NaCl solution was investigated before and after application of titanium dioxide (TiO₂) thin-film coatings deposited using radiofrequency sputtering. The objective of this work was to evaluate the influence of a thin-film barrier on the electrochemical response and corrosion kinetics of stainless steel exposed to a simulated seawater environment.

Electrochemical Impedance Spectroscopy (EIS) and linear polarization techniques were employed to assess corrosion resistance and mechanisms of bare and coated specimens. Impedance measurements were conducted over a frequency range of 0.1 Hz to 1 MHz to evaluate coating integrity, charge transfer resistance, and capacitive behavior at the metal–electrolyte interface. Corrosion rates were determined using polarization resistance measurements and Tafel extrapolation methods to quantify kinetic parameters.

The EIS results demonstrated a significant increase in impedance and charge transfer resistance for TiO₂-coated SS316 compared to the uncoated substrate, indicating improved barrier properties and reduced electrochemical activity in chloride-rich solution. Linear polarization data confirmed a reduction in corrosion rate for coated specimens, validating the protective effectiveness of TiO₂ thin-film. Enhanced corrosion resistance is attributed to the formation of a dense and chemically inert TiO₂ layer that restricts electrolyte penetration and suppresses anodic and cathodic reactions on the stainless steel surface. The TiO₂ thin film also acts as a diffusion barrier limiting oxygen transport to the metal surface, reducing electrochemical activity at the metal–electrolyte interface. This behavior is relevant in chloride environments where localized corrosion mechanisms, including crevice corrosion, may be influenced by oxygen availability.

These findings highlight the potential of RF-sputtered TiO₂ thin-film coatings as a durable corrosion protection strategy for stainless steel components operating in chloride-containing environments.

MXenes are highly promising materials for self-healing coatings on Mg alloys. The high aspect ratio of MXenes material ensures its excellent physical barrier performance, prolongs the invasion path of corrosive ions, and gives it excellent corrosion resistance. In our various studies, Y-modified MXenes/MgAl LDHs composite coatings were successfully grown in situ on AZ31 magnesium alloy by the hydrothermal method. Rare earth ions Y increase the compactness of the corrosion product film, and the composite coating shows a very low corrosion current density of 9.12×10^-9 A·cm^-2. MXenes are good carriers of corrosion inhibitors due to their high specific surface area. 4-aminophenol@MXenes are prepared and introduced onto MgAlLa LDHs via a low-temperature water bath method. The scratched composite P/MgAlLa LDHs-M@A coating exhibits approximate |Z|_{0.01 Hz} with unscratched samples even after 12 h corrosion. Outer (PEI/MXene)_n-based layers were assembled on the surface of MgAl-V₂O₇⁴⁻ LDHs film via the layer-by-layer (LbL) approach to further explore its physical barrier-blocking effect and protection mechanism for corrosion inhibition. In another study, electrophoretic deposition technology was further utilized to incorporate disordered MXenes onto the 2,5-Pyridinedicarboxylic acid (2, 5-PDCA)-modified ZnAl-LDHs coating. MXenes uniformly coated the 2,5 PDCA-LDH film, forming a protective barrier against corrosive species while simultaneously establishing a lubricating layer. Additionally, MXenes are applied as nanofiller to enhance the performance of epoxy resin (EP) coating, where the MXenes are modified with in situ grown ZnAl LDHs. The synergistic physical barrier effect of LDHs and MXenes effectively enhance the corrosion and wear resistance of EP coating.

Abstract: A variety of methods are employed for evaluating the sealing quality of anodized aluminium. These tests are based on various mechanisms, can be qualitative or quantitative, and vary in the level of detail and preparation necessary to obtain good results. In this work, we evaluate a variety of electrochemical methods (electrochemical impedance spectroscopy (EIS), potentiodynamic polarization, and open circuit potential (OCP) evolution with time measurements) as candidates for sealing quality evaluation. The desirable criteria for a target electrochemical test method are that it is non-destructive, requires little or no prior sample preparation, is applicable to long anodized profiles, is completed in a short time, and yields results that are interpretable with very little or no post-test data processing. Selected electrochemical tests were carried out on sulphuric acid anodized AA6060 aluminium alloy samples hydrothermally sealed at a constant time (30 minutes) in de-ionized water at varying temperatures, 50 ^°C, 60 ^°C, 70 ^°C, 80 ^°C, 90 ^°C, and 98 ^°C, respectively. The feasibility of a simple electrochemical method (OCP evolution) for evaluating the barrier properties (corrosion resistance) of sealed and partially sealed anodized aluminium samples is demonstrated.

Ackowledgements

This work was developed in the scope of the R&D Project in Co-promotion “ANOD 2: Advancing Anodization for Energy Efficiency and Enhanced Durability”, operation no. 20585, operation code in the COMPETE2030 Funds Desk FEDER-02055500, with funding FEDER,Fundo Europeu de Desenvolvimento Regional, through the Research and Development Incentive System, within the scope of Portugal 2030, and had laboratory support from project UID 00481/2025 Centre for Mechanical Technology and Automation, https://doi.org/10.54499/UID/00481/2025, supported by national funds from FCT, Fundação para a Ciência e a Tecnologia, I.P.

In drainage canals, steel sheet piles are known to be susceptible to localized corrosion, particularly around water level fluctuation zones. In Japan, various repair methods have been applied to extend the service life of existing facilities. However, some repaired steel sheet piles exhibit further deterioration. In this study, the feasibility of evaluating re-deterioration is investigated in an agricultural drainage canal, where further deterioration of the repaired coating system has progressed, using image data acquired by unmanned aerial vehicles (UAVs) and from the ground. The investigated canal had been repaired using several coating materials, including an ultra-thin urea-urethane coating, thin-film epoxy resin coating, ultra-thick polyurethane-resin coating system, and precast concrete panel lining system. Both image data and the on-site visual inspection indicate that the deterioration condition varies depending on the repair method, and different types of defects are identified for each repair method. Deteriorations such as blistering, delamination, peeling, rust staining, and cracks in the concrete panel are observed. These results suggest that image data can provide basic information for evaluating characteristics of re-deterioration after repair. In future work, point cloud data acquired by UAVs will also be incorporated to quantify the degree of deterioration and to further refine the evaluation method.

In the automotive industry, the selection of structural materials plays a critical role in ensuring component durability and performance. Among these, seats hold significant importance across all vehicle types—whether three-wheelers or four-wheelers. Based on the working mechanism, these seats can be hydraulic-based, spring-loaded or air suspension types, among others. Usually, high-strength steels are used to manufacture these seats. One such example is pneumatic seats, which are designed for multidirectional movement and are equipped with a seat slider assembly. Recently, we received a failed seat slider assembly from the plant. It was observed that the tooth of the locking bracket had completely broken off from the parent part.

The locking bracket features a toothed design which engages with the seat slider cavities to secure the seat position in multiple X-Y directions, ensuring movement of the seat. This part is manufactured using high-strength hot-rolled steel (SPFH 590 grade). Due to continuous engagement and repetitive cycles, the teeth are prone to wear; hence, carbonitriding surface treatment is applied to the toothed region to enhance surface hardness, achieving a hardness range of 625–725 HV.

During fractography analysis, intergranular fracture, along with multiple cracks, was observed. A study of the manufacturing and heat treatment process revealed that the part undergoes case hardening during carbonitriding, along with ammonium–hydrogen gas mixture exposure, which results in hydrogen pickup. This hydrogen diffuses inside the material and accumulates on the grain boundaries, eventually weakening them, which can further lead to intergranular fracture. To further mitigate the issue, the amount of diffusible hydrogen needs to be decreased, which can be achieved by increasing the tempering temperature to 250 °C–300 °C.