Aluminum alloys such as AA6061 are widely deployed in marine and chloride-containing environments but remain vulnerable to localized pitting corrosion once the native oxide film is destabilized. This work presents a scalable, PFAS-free surface engineering strategy that suppresses pitting corrosion through nanosecond laser manufacturing of triple-scale hierarchical architectures combined with siloxane-based chemical functionalization. Nanosecond IR laser texturing generates fully covered grid and grid-plus-double-diagonal (G+DD) patterns consisting of micron-scale trenches and ridges, submicron resolidified features, and nanoscale cauliflower-like structures enriched with aluminum oxide. This multiscale roughness increases the effective surface area, enhances oxide density, and promotes robust chemical anchoring of a non-fluorinated OTS–PDMS hybrid layer, which lowers surface energy while maintaining mechanical stability. The optimized (LT (GDD) + CT) surface exhibits stable Cassie–Baxter wetting behavior with a static water contact angle of ~158°, advancing and receding angles above 159°, a roll-off angle of ~2°, and an ultra-low normalized surface free energy of ~5.6 mN m^-1, indicating strong suppression of polar interactions and reduced electrolyte affinity. Electrochemical characterization in 0.6 M NaCl reveals a pronounced positive shift in pitting potential and orders-of-magnitude increases in low-frequency impedance magnitude and polarization resistance relative to bare, chemically treated-only, and laser-only controls. Time-dependent electrochemical impedance spectroscopy conducted over 17 days demonstrates sustained high corrosion resistance and minimal degradation of the hierarchical morphology. Post-immersion microscopy confirms limited localized attack and preserved surface features on the fully textured and functionalized surface, whereas partial-coverage or single-treatment samples exhibit evident pitting and surface breakdown. The results demonstrate that process-driven nanosecond laser texturing coupled with PFAS-free siloxane functionalization provides a manufacturable, industry-compatible route to durable, non-wetting, highly robust, and sustained corrosion-resistant aluminum surfaces suitable for aerospace, marine, and transportation applications without reliance on fluorinated chemistry.

Introduction: Recent advancements in the Directed Energy Deposition Wire Arc (DED-Arc) method for Additive Manufacturing have made it possible to restore damaged surfaces of pipes. Main focus is on pitting corrosion defect elimination because they are extremely detrimental when affecting large areas and may lead to safe operation impairment and subsequent decommissioning.

Method: A pipe made of 14MoV6-3 (1.7715 according to EN 10027) material sustained pitting and was heavily corroded. For the DED-Arc, filler wire was selected with a minimum molybdenum content (Ni-Alloy 625), which is very resistant to generalized aqueous acidic corrosion, pitting and stress corrosion cracking (SCC) in chloride-containing environments. No post-weld heat treatment (PWHT) was allowed in order not to corrupt the pipe outer geometry. Extracted samples were tested with microhardness measurement: bond strength, microcracking detection, porosity, interface zones assessment as well as microstructural analysis. After the application, visual testing (VT) for the surface quality was performed followed by ultrasonic testing (UT) as a non-destructive evaluation of the restored areas with checking for disbonding and internal imperfections.

Results: The DED-Arc method allows the restoration to be performed with 50 % overlapping of each successive pass and performing temper beat technique thus eliminating the need for PWHT. Strictly controlled parameters provide low dilution between material base and overlay with strong metallurgical bonding. The process has 0.4 to 0.7 KJ/mm heat input, no defects and the restored surface pass UT and VT. Pitting holes have been filled in. The deposition rate achieved is 5 kg/h. The corrosion behavior of the obtained cladded pipe proves satisfactory.

Conclusion: Successful restoration of corroded pipe has been performed by DED-Arc with improved rates of metal deposition and high quality which allow cost saving and extended equipment life.

Funding: The author acknowledges support from project BG16RFPR002-1.014-0005.

Organic protective coatings are extensively employed to reduce the corrosion of metallic materials in a wide range of industrial applications. However, mechanical defects such as scratches, pinholes, and microcracks can significantly impair their barrier properties, providing pathways for aggressive species and promoting the onset of localized corrosion. In the present work, supramolecular and thermoplastic ionic polymers containing carboxylic acid functionalities, partially or fully neutralized with metal ions, were synthesized and deposited onto aluminum alloy substrates. These coatings were designed to impart enhanced anticorrosive performance while simultaneously exhibiting self-healing and photocatalytic capabilities. Surface topography, coating integrity, and corrosion-related degradation were systematically analyzed using scanning electron microscopy and atomic force microscopy. Interfacial interactions, elemental distribution, and complex formation within the coatings were examined through energy-dispersive X-ray spectroscopy and X-ray diffraction analyses. The photocatalytic performance of the coatings was evaluated under controlled light exposure, revealing effective self-cleaning behavior without compromising coating adhesion or structural stability. Corrosion resistance was assessed using open-circuit potential measurements, potentiodynamic polarization, and electrochemical impedance spectroscopy in aggressive corrosive environments. Autonomous self-healing behavior was investigated by introducing artificial defects into the coatings, with the recovery process monitored using in situ Raman spectroscopy and electrochemical impedance spectroscopy. The developed composite coatings demonstrated a progressive increase in impedance modulus and polarization resistance with immersion time, confirming durable corrosion protection. Overall, the results highlight the successful integration of corrosion resistance, self-healing ability, and photocatalytic functionality within a single coating system.

This research was supported by the Research Excellence Partnerships-SEA project: GoSmartSurf; project code: 10574.

Biodegradable Mg alloys are attractive for temporary orthopedic implants because they can resorb in vivo, potentially eliminating the need for removal surgeries and reducing stress shielding due to their bone-like elastic modulus. However, clinical adoption is limited by rapid, non-uniform degradation that can compromise mechanical integrity, cause hydrogen gas evolution, and result in insufficient bioactivity for osseointegration. One effective strategy to address these limitations is the use of dense, adherent Ti–Zr-based thin films that serve as barrier/interfacial layers while preserving biocompatibility. In this context, we obtained Ti–Zr–X coatings (X = Cu, Nb, or CuNb) on AZ31B substrates (15 mm in diameter, 2 mm thick) by using unfiltered cathodic arc evaporation. Coating deposition was carried out at room temperature by using a substrate bias of −100 V and an Ar flow of 20 sccm, with composition-specific cathode currents and deposition times. Prior to corrosion-based investigations, structural and microstructural analyses were conducted to confirm the intended elemental composition. SEM observations revealed dense and homogeneous surfaces, while GIXRD results indicated a mixed crystalline microstructure for all Ti-based coatings, consisting of hexagonal TiZr, as well as tetragonal TiCu and/or cubic TiNb phases. Potentiodynamic measurements showed that the corrosion response strongly depends on coating chemistry, with the TiZrNb coating exhibiting the highest improvement in corrosion resistance among all investigated systems. This behavior was further supported by electrochemical impedance spectroscopy results, which revealed higher polarization resistance and more stable behavior for TiZrNb, indicating enhanced barrier properties and improved protection of the AZ31B substrate.

This work was supported by the Romanian Ministry of Research, Innovation and Digitization through CCCDI–UEFISCDI, project no. PN-IV-P7-7.1-PTE-2024-0618 and PN-IV-P8-8.3-PM-RO-TR-2024-0065, within PNCDI IV, as well as through the National Research Development and Innovation Plan 2022–2027, Core Program, Project no: PN 23 05, contract no. PN11N-03-01-2023.

This work explored the use of density functional theory (DFT) first principles and FactSage simulations to predict suitable Ni-Cr-Al alloy compositions that can be used in the petrochemical industry. Currently, there is a need for improving production efficiency in the petrochemical industries, resulting in the use of higher operating temperatures and pressures, as well as higher levels of carbon dioxide (CO₂). High-temperature operations results in metal pitting that occurs in carbon supersaturated gaseous environments at temperatures ranging from 400 to 850°C. The simulated phase diagrams of Ni-Cr, Ni-Al and Ni-Cr-Al alloys showed that the stable phases were found to be BCC and FCC. BCC is chromium (Cr)-dominant, and FCC is nickel (Ni)-dominant. The Gibbs free energy of the alloys shows that the alloys are thermodynamically stable at 650°C. CASTEP simulation was used to calculate the mechanical properties of Ni-Cr-Al alloys using the supercell approach. From the calculations, we can see the suitable working range for Cr is between 18.25 and 25 at.%, and with Al 6.25 at.% it showed to be the best alloying concentration for the ternary alloy. The metal dusting results showed that with CO exposure, the alloys experience carbon attack at low CO exposure, due to a minimum amount of oxide layer that is present. With the exposure to CO-H₂-H₂O, all samples had oxide layers that formed. It can be concluded that Ni - 30.67 at.% Cr - 6.25 at.% Al performed better as a metal dusting resistance alloy when exposed to CO and CO-H₂-H₂O at 525 and at 650°C.

In this study, the anti-corrosive performances and coating properties of alkyd resins chemically modified with phenolic, urethane, THEIC (1,3,5-tris-(2-hydroxyethyl)isocyanurate), silicone and epoxy on metal surfaces were comparatively evaluated. Despite their advantageous properties in the paint industry, alkyd resins exhibit limited barrier performance against water, ions, and corrosion due to the hydrolysis-prone ester bonds in their structure. In order to eliminate this disadvantage, various chemical modification methods are recommended in the literature. According to the literature, in alkyd resins, phenolic modification creates an effective physical barrier against water vapor and chloride ions thanks to its dense cross-linked three-dimensional network structure. TDI-based urethane modification suppresses the susceptibility of ester bonds to hydrolysis, enhancing chemical stability, mechanical rigidity, and flexibility. It is believed that THEIC modification with trifunctional structure accelerates the curing kinetics and raises the glass transition temperature (Tg). Epoxy modification strengthens the hydrophobic characteristic, especially with alkali resistance. Silicon modification, on the other hand, significantly improves hydrophobic and environmental strength thanks to its low surface energy and high Si–O bond energy. In this study, phenolic-, urethane-, THEIC-, epoxy-, and silicone-modified alkyd resins were synthesized, and white paint recipes were prepared. The corrosion performance of these paints was evaluated by salt spray test. The physical and mechanical properties of the prepared paints were examined by drying time, gloss, König hardness, and adhesion (crosscut) tests. Surface hydrophobicity was evaluated by contact angle measurements, and morphological and structural features were determined by SEM, XRD, and FT-IR analyses. This study comparatively considers the corrosion resistance of different alkyd modifications. The results obtained revealed that the synthesized modified alkyd resins can exhibit good-to-excellent corrosion resistance under harsh environmental conditions. This research is expected to guide high-performance and alternative alkyd resin systems that can be developed in the future.

Magnesium and its alloys are attractive structural materials due to their low density, high specific strength, and good castability and machinability, enabling their widespread use in transportation, aerospace, and biomedical applications. However, magnesium is highly reactive and therefore prone to rapid corrosion, which limits the durability and service life of magnesium-based components. Corrosion can occur through several mechanisms, including general, crevice, and microbiologically influenced corrosion. Environmentally acceptable inhibitors such as carbonates and cerium-based compounds are promising for slowing magnesium degradation, but further development is still needed.

In this work, a sustainable multilayer coating system was developed to improve magnesium corrosion resistance. A hydrothermally synthesised cerium carbonate hydroxide (CeCO₃OH) base layer was first applied, acting as a protective and pH-buffering passivation layer. To enhance adhesion and connectivity between layers, sodium dodecylbenzene sulfonate (SDBS) was introduced as an interfacial modifier. Finally, a biopolymer epoxy topcoat was applied to provide an additional physical barrier against electrolyte penetration. The optimal SDBS concentration was 0.05 M, facilitating the strongest interaction between the layered hydroxide and epoxy topcoat.

Scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDX), and X-ray diffraction (XRD) confirmed a highly crystalline CeCO₃OH layer with high cerium content. Corrosion performance was evaluated using potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS) in 3.5 wt % NaCl over a wide pH range (2–10). The best coating system (Mg/LH/S_0.05/T) showed excellent protection, with a very low corrosion current of 5.2 nA and a corrosion potential of −1.58 V. Strong corrosion resistance was maintained across pH 2.0 (5.5 nA) to pH 10.0 (2.0 nA). EIS results showed significantly increased impedance, low capacitance (4.5 × 10⁻¹¹ F), and polarisation resistance of 3.6 × 10⁵ Ω. The coating remained stable for up to 40 days, with gradual loss of protection observed after 40–50 days of immersion.

Plasma Electrolytic Oxidation (PEO), also known as Micro Arc Oxidation (MAO), has recently attracted significant interest due to its ability to produce thick, well-adherent coatings with excellent corrosion and wear resistance. Key features of PEO coatings include the high porosity of the outer layer and the capability to incorporate particles dispersed in the electrolyte directly into the growing oxide layer. This latter feature enables functionalization of the coated surface and improves its corrosion properties.

In this study, PEO coatings were produced and characterized on aluminum and magnesium alloys by incorporating metallic and non-metallic particles. The coatings were synthesized using different current modes, namely direct current and pulsed unipolar current, with particle incorporation achieved by simple dispersion of the particles in the PEO electrolyte. Various types of particles were embedded in the coatings, including graphite nanoparticles to enhance wear resistance; metallic particles (copper or silver) to impart bactericidal, fungicidal, or antifouling properties; glass particles to improve wear and corrosion resistance; and titanium dioxide particles to generate photocatalytic surfaces. In all cases, the impact of particle incorporation on corrosion properties was also evaluated.

The resulting coatings were characterized on both the surface and cross-section using scanning electron microscopy (SEM) and X-ray diffraction (XRD) to confirm particle incorporation and to analyze the microstructure and morphology. Functional performance was further evaluated through corrosion, wear, biological, and photocatalytic tests, depending on the incorporated particles. In particular, corrosion properties were evaluated through electrochemical tests. In all cases, significant particle incorporation was achieved, resulting in coatings with enhanced, well-defined functional properties. In most cases, particle incorporation also leads to an improvement in corrosion properties.

With the intensification of coastal water pollution and the increasing pressure on nearshore resources, marine aquaculture is gradually shifting toward offshore and deep-sea environments. Deep-sea aquaculture facilities are required to operate for extended periods under complex marine conditions, including high salinity, fluctuating dissolved oxygen levels, and severe biofouling. Therefore, the development of effective structural corrosion protection technologies for deep and far-sea aquaculture equipment is of critical importance. Among these technologies, surface treatment and protective coating systems play a pivotal role in mitigating and delaying corrosion-related degradation at material surfaces and interfaces, which govern most corrosion phenomena. Studies have shown that corrosion mechanisms and rates vary significantly with water depth and environmental conditions. In deep-water zones, reduced dissolved oxygen concentrations may inhibit oxygen-dependent electrochemical corrosion processes, while simultaneously promoting sulfide-induced corrosion. Under anaerobic conditions, the activity of microorganisms, such as sulfate-reducing bacteria, is enhanced, posing a serious threat to coating integrity and interfacial stability. In contrast, nearshore environments are more susceptible to photochemical reactions and intense biofouling due to higher light availability, which accelerates coating degradation and increases the risk of localized corrosion at surface defects. In response to these challenges, this study focuses on surface treatment strategies and advanced coating technologies for deep-sea aquaculture equipment, along with a comprehensive discussion of complementary corrosion protection methods. The aim of this paper is to develop an integrated corrosion prevention strategy based on coating protection in conjunction with other protective techniques, thereby reducing corrosion damage to marine ranching facilities and addressing the harmful by-products generated during corrosion processes. By systematically analyzing the surface and interfacial degradation behaviors of marine aquaculture equipment, this research provides practical guidance for the design of durable and environmentally adaptive surface protection systems, contributing to the sustainable development of deep-sea aquaculture infrastructure.

Maintaining corrosion-free equipment in water purification processes is vital, as these processes aim to produce fresh water. Corrosion is a degradation process that affects metals, and heat exchangers are constructed from metals or alloys. This project analyzes and mitigates corrosion in 316L stainless steel heat exchangers that use lithium bromide (LiBr) as an absorber. These units are used in heat pumps for water purification. The effects of forging and nitriding processes will be studied on test specimens to evaluate their corrosion resistance, mechanical properties, and improved longevity. Subsequently, these processes will be applied to a full-scale heat exchanger. Twenty samples will be taken: five will be nitrided, five will be forged, and five will be both forged and nitrided. Both as-received and forged, nitrided, and nitrided-forged samples will be characterized for their mechanical behavior (wear, hardness, and tensile strength tests) and corrosion resistance using electrochemical techniques such as potentiodynamic polarization, electrochemical impedance, and electrochemical noise in a LiBr/H₂O electrolyte. The expected results are an austenitic steel with high resistance to pitting corrosion, ideal for the heat exchanger industry, as developing materials to mitigate corrosion in this equipment remains a challenge. A scale-model heat exchanger will also be developed to assess its functionality over time.