Corrosion is a natural phenomenon that significantly affects metal structures, leading to deterioration, reduced service life, and structural failures, with severe economic and environmental consequences. The Organization for Economic Co-operation and Development (OECD) estimates that corrosion accounts for up to 3% of the GDP in developed countries. In Chile, a country with an extensive coastline and a strong industrial sector, critical infrastructures such as bridges, power plants, and offshore platforms are continuously exposed to corrosive environments. Climate change exacerbates these conditions by increasing coastal salinity and acid rain, accelerating metal degradation, raising maintenance costs, and impacting sustainability.

Traditional anticorrosive coatings contain materials with significant health and environmental risks, including epoxy resins with bisphenol A (BPA), carcinogenic lead chromate pigments, volatile organic compounds (VOCs), and bioaccumulative biocides. Developing safer and sustainable alternatives is crucial to reducing these risks while maintaining corrosion protection effectiveness. This study explores the use of Pinus radiata bark wax extracts as a novel raw material for sustainable anticorrosive coatings. Utilizing this abundant forestry byproduct promotes circular economy principles by repurposing waste while reducing synthetic material dependency and carbon footprint.

Electrochemical impedance spectroscopy (EIS) tests were conducted following ASTM G106 standards to evaluate corrosion resistance. The developed coating exhibited impedance modulus values ranging from 10⁸ to 10¹¹ Ω/cm², demonstrating excellent corrosion protection. To complement the study, mechanical tests were conducted using commercial coatings. Additionally, in vitro cytotoxicity tests using human skin cells (HaCaT) showed cell viability and proliferation comparable to control samples, confirming low toxicity. These results validate the potential of Pinus radiata bark wax-based coatings as a multifunctional, cost-effective, and environmentally friendly alternative to conventional anticorrosive solutions.

Epoxy resins serve as anticorrosive coatings due to their robust mechanical properties, chemical resistance, and adhesion. Enhancing these coatings with nanoparticles—particularly titanium dioxide (TiO₂)—has proven effective in improving both corrosion resistance and other functional properties. In this work, we synthesized a photoactive TiO₂-based ZnAl-layered double oxide (TiO₂-LDO; 1:10) nanocatalyst via a wet impregnation method and incorporated it into an epoxy matrix. The epoxy resin, formulated with 2 wt.% TiO₂-LDO, was applied to AA2024 substrates using a coating bar coater, yielding a cured film thickness of 20 ± 2 µm. The developed TiO₂-LDO nanocatalyst exhibited high selectivity in the NOx abatement and a minimum NO₂ release (3-4%), achieving remarkably up to an 80% NO photoconversion efficiency under 20 W/m² of irradiation in a customized continuous-flow portable photoreactor, designed specifically for NOx studies. In comparison, while TiO₂ (anatase) achieved a similar NO conversion efficiency, it generated 20–25% NO₂ as a byproduct, which is even more toxic than NOx, whereas LDO alone produced minimal NO₂ but achieved a lower NO conversion efficiency of 25–30%.

Electrochemical impedance spectroscopy (EIS) over 28 days revealed that incorporating TiO₂-LDO into the epoxy coating provided a comparable corrosion resistance to the pure resin. However, the improvement was pronounced when the systems were exposed to UV irradiation (10 days of aging with fluorescent source with λ_max = 365 nm, 20 W·m⁻²), which induces micropore formation in the pure epoxy film compared to epoxy with TiO₂-LDO, and thus improved corrosion resistance for the epoxy composite on AA2024. The results underscore the dual functionality of TiO₂-LDO as both a photoactive nanocatalyst (air pollution) and an effective anticorrosion additive, offering a promising, environmentally friendly solution for UV-resistant corrosion protection.

Water-based coatings materials, due to their desirable properties such as very good resistance to weather conditions and flexibility as well as easy application, are used for both decorative and protective purposes. The ability of the coatings to transport water can effect fungi growth, loss of adhesion, or the penetration of aggressive ions from rain into the substrate. Therefore, determining the water transport properties of water by paints is a key point in determining their protective properties.

This study investigated the effects of preparation, conditioning, and testing methodologies on the water vapour permeability properties of waterborne coatings. The study was divided into two parts. In the first part, the influence of the binder content of the paint product, the film thickness, and the presence of different substrates on the water vapour permeability values obtained was determined. In the second part, the influence of conditioning and testing methods was investigated. The conditioning method was selected based on the target use of the coating (indoor/outdoor), in accordance with the instructions in the PN-EN ISO 7783:2018-11 standard. However, due to the possibility of applying outdoor paints indoors, they were conditioned using both methods. Since the standard does not indicate how to select a test method for each group of prepared coatings, wet and dry cup methods were performed.

The results obtained show that the water vapor transmission rate decreases with increasing binder content, and the observed differences are greater for thicker coatings. The water vapor transmission through the coating on the substrate depends on the interaction between them. The coating conditioning method has the greatest influence on its ability to transport water; therefore, to determine the protective properties of the coating, it is important to choose test conditions that best represent the actual conditions in which the coating will be used.

This study introduces an innovative experimental setup for high-temperature fatigue testing of full-scale nickel-based turbine blades protected with aluminide coating, aiming to replicate operational conditions and enhance service life predictions. A patented grip system was developed to enable precise determination of the S–N curve and hysteresis loop evolution under simulated extreme conditions. The blades were tested at 950°C with cyclic bending loads ranging from 5.2 kN to 6.6 kN at a frequency of 10 Hz. A preliminary bending test established the force–displacement relationship, providing critical input for fatigue testing parameters. The setup integrates an Inconel alloy testing stand with an induction heating system, ensuring uniform temperature distribution with deviations limited to ±3°C. Advanced monitoring techniques allowed for high-frequency data acquisition, facilitating the capture of force-displacement relations and hysteresis loop development. Results revealed distinct behavioral transitions, including elastic responses and plastic deformations at higher force amplitudes, contributing to a comprehensive understanding of fatigue-induced damage mechanisms. Key findings underscore the effectiveness of this methodology in capturing the complex mechanical responses of turbine blades under high-temperature cyclic loading. The proposed setup addresses the limitations of conventional standardized specimen testing by enabling full-scale component evaluation, thus offering significant advancements in material performance assessment for aerospace applications. This work represents a critical step toward optimizing the design and durability of high-temperature components, aligning with the demanding requirements of modern turbine technologies.

Previous investigations have revealed that Atomic Layer Deposition (ALD) layers on Physical Vapor Deposition (PVD) coatings lead to pinhole defect sealing, which results in improved coating corrosion properties. However, despite this, the influence of PVD defect size on the sealing efficiency of ALD layers remains poorly determined. This study aimed to evaluate the corrosion properties of hybrid PVD/ALD layers with a focus on how the influence of PVD defect size affects the sealing efficiency of ALD layers. The corrosion resistance of PVD TiN coatings and TiN combined with ALD Ti-O layers (amorphous and anatase phases) was investigated in phosphate-buffered saline solution (PBS). Corrosion experiments were conducted on circular areas of 4 mm in diameter using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization (PD) measurements. Confocal and tactile profilometry were performed before and after the corrosion tests to identify and quantify the PVD coating growth defects. To examine the thickness and uniformity of the ALD layers, scanning electron microscopy (SEM) was utilized on cross-sections of PVD defects prepared by focused-ion beam (FIB). The results revealed that the increased number of protrusion defects, with heights exceeding 2 µm, correlates with a decrease in impedance for PVD-coated samples. The deposition of ALD layers significantly improved the corrosion resistance of samples. Cross-sectional FIB-SEM analysis confirmed uniform coverage by the ALD layer without visible cracks across all investigated ALD layers. However, corrosion tests revealed that the amorphous TiO₂ ALD layer exhibited superior PVD defect-sealing efficiency compared to the anatase TiO₂ layer. This suggests that the presence of grain boundaries in the anatase TiO₂ ALD layer contributes to its lower sealing efficiency. The application of ALD layers on PVD-coated samples, by forming a hybrid coating, offers a promising solution for applications requiring enhanced corrosion resistance alongside adequate surface mechanical properties.

The surfaces of industrial components intended to be coated with wear-resistant coatings are frequently not polished. On the contrary, during the coating development, its properties are always evaluated on highly polished surfaces. These differences in surface conditions may lead to erroneous estimation of the future coated part properties. Contemporary hard coatings that are used for enhancing tribological performance are produced with different layer designs, namely single layers, multi layers, and nanolayers. However, their performance on surfaces with different roughnesses is addressed to a minimal extent in the literature. This investigation examined three kinds of coatings of different layer designs deposited by magnetron sputtering, namely TiAlN (single layer), TiAlN/CNx (dual layer) and AlTiN/TiN (nanolayer) coating. Coatings were deposited on steel substrates with four degrees of roughness. The coatings’ adhesion was evaluated by scratch test performed parallel and perpendicular to the grinding marks. The tribological behavior of the coatings was assessed by dry-reciprocating the sliding test against an Al₂O₃ counter ball. All samples were evaluated before and after the experiments through 3D tactile profilometry, confocal optical microscopy, and energy dispersive spectroscopy. In all cases, the surface roughness of the samples increased after the coating deposition, and these surfaces belong to the range of fine surface finishes, namely Sa=12–545 nm. Within the investigated range of surface roughness, coatings with different layer designs behaved differently according to changes in surface roughness. TiAlN and TiAlN/CNx coatings showed no dependence on scratch adhesion or tribological behavior on surface roughness. For the roughest surface, a reduction in adhesion and an increase in wear rate were both observed. The AlTiN/TiN nanolayer coating displayed the largest sensitivity of adhesion on roughness and scratching direction. The coefficient of friction and wear rate of AlTiN/TiN coating increased when the roughness was larger than Sa ≈ 100 nm. This indicates that future investigations should cover a wider range of nanolayer coatings.

Post-combustion CO₂ capture using aqueous amine solutions has gained significant popularity in recent years, owing to their exceptional absorption capacity, rapid reaction kinetics, and ability to regenerate efficiently. However, a major challenge lies in the corrosive nature of amines after reacting with CO₂, which can lead to significant operational issues in process equipment. Beyond CO₂, the oxidative degradation of amine solvents further influences corrosion. This degradation is accelerated by oxidative agents, such as O₂, SOx, and NOx impurities in flue gas, which interact with amine solutions to form various degradation by-products .

This study focused on investigating the corrosion behavior of 316L and 304L stainless steels (SS316L and SS304L)—widely used in carbon-dioxide capture units—when exposed to both degraded and non-degraded MEA aqueous amine solutions containing SOx and NOx pollutants, under both CO₂-loaded and unloaded conditions. The research assesses the impact of MEA degradation on the corrosion characteristics of these stainless steels, using Potentiodynamic Polarization and Electrochemical Impedance Spectroscopy. Scanning electron microscopy (SEM) was used to gain further insights into corrosion mechanism.

The results revealed that the degradation of the amine solutions, whether CO₂-loaded or unloaded, promoted the corrosion in both stainless steels. Corrosion rates were higher in degraded solutions compared to non-degraded ones, indicating reduced corrosion resistance. This was also verified by the lower total impedance values observed in Bode diagrams.

Funding: This work has received funding from the European Union's Horizon Europe research and innovation program under grant agreement No. 101075727. The views and opinions expressed are, however, those of the author(s) only and do not necessarily reflect those of the European Union or European Climate, Infrastructure and Environment Executive Agency (CINEA). Neither the European Union nor the granting authority can be held responsible for them.

CrMoSiN films with varying Mo and Si contents were deposited on SS316L stainless steel by Physical Vapor Deposition (PVD) to evaluate their corrosion and electrochemical properties as bipolar plates for Polymer Electrolyte Membrane Fuel Cells (PEMFCs). The sputtering current of Mo and Si targets was adjusted to obtain different compositions in the CrMoSiN coatings, enabling a systematic study of the influence of these elements on the performance of the coatings. Scanning Electron Microscopy (SEM) revealed that the CrMoSiN coatings have a dense and uniform microstructure, which is essential for improving their mechanical and corrosion-resistant properties. X-ray Diffraction (XRD) analysis confirmed that the coatings exhibit a preferred orientation along the (200) direction, indicating good crystalline structure and stability. The effects of Mo and Si incorporation on the corrosion properties of CrMoSiN coatings were thoroughly investigated in simulated PEMFC environments, which mimic the harsh conditions within fuel cells. Potentiodynamic polarization tests and Electrochemical Impedance Spectroscopy (EIS) results demonstrated that the incorporation of Mo and Si significantly enhances the corrosion resistance of the coatings, making them more durable and effective in these environments. The findings suggest that CrMoSiN coatings, particularly those with optimized Mo and Si content, have promising potential as protective materials for bipolar plates in PEMFCs, significantly improving their efficiency and longevity under operational conditions. The corrosion mechanism of the CrMoSiN coatings was also investigated and discussed in detail.

Marine biofouling is a phenomenon in which unwanted organisms adhere to submerged surfaces, altering their chemical, physical, and functional properties. This process begins with forming a biofilm, known as microfouling, composed of bacteria that modify the affected surface. Subsequently, larger organisms such as algae, mollusks, and crustaceans settle on the biofilm, intensifying the deterioration in a process referred to as macrofouling.

In response to this challenge, developing polymers with antifouling properties represents a disruptive advance in managing marine biofouling. These innovative materials integrate graphite oxide (GrO) nanomaterials and confer surfaces with properties that effectively inhibit organism adhesion. Polymers modified with 5% GrO have proven to be highly effective, achieving up to a 305% reduction in organism accumulation compared to untreated surfaces after one year of exposure to real marine conditions, demonstrating their durability and resistance in adverse environments.

These polymeric matrices excel in their capacity to combat biofouling and their remarkable versatility across various industrial applications. In the renewable energy sector, their integration into offshore wind turbines and tidal energy platforms would enhance operational efficiency by significantly reducing maintenance costs and efforts associated with the accumulation of marine organisms. In sustainable aquaculture, these matrices could extend the lifespan of nets and cultivation cages, considerably lowering cleaning and biofouling management costs. In maritime transportation, their application to ship hulls would optimize fuel consumption by reducing water friction, contributing to carbon emission reductions, and promoting more sustainable operations. Finally, these surfaces protect research equipment and sensors in ocean exploration, ensuring their functionality over extended periods in extreme and challenging accumulating conditions.

Developing these technologies is essential to addressing future challenges in marine environments. By combining operational efficiency and versatility, these polymeric matrices are positioned as a fundamental component in the design of advanced materials, with the potential to transform maritime industries and related sectors .

Secondary aluminum production through the recycling of aluminum chips originating from machining proceedings (e.g. milling, drilling) has occupied the top position among the exploitation procedures of wastes in the last decade. In particular, the solid-state method that replaces the conventional melting and casting stages with a cold pre-compaction stage before the final hot extrusion is a promising new field of interest, taking into account the energy consumption, material loss, processing steps, environmental contamination, cost, etc. The literature results reveal that material produced by the innovative processing route (including cold compaction followed by hot extrusion) is optimum, with very competitive mechanical properties. The present study explores the influence of different heat treatments (no heat treatment, natural aging, artificial aging) on the chip-based hot-extruded aluminum alloy AA6060's fatigue and fatigue corrosion behavior. Experiments were performed on cast-based hot-extruded specimens for comparison reasons. In addition, a detailed microstructural analysis of the micro-morphological fatigue failure features was carried out.

Although the results pointed out the supremacy of cast-based material in the majority of cases of fatigue and fatigue corrosion, the significance of microstructural coherency was highlighted among chip boundaries. Improving the chip bonding quality could lead to a remarkable enhancement in the fatigue life of the recycled chips subjected to hot extrusion and heat-treated processes.