Search Results (228)

The present work compares the corrosion performance of additively manufactured (AM) Ti-6Al-4V ELI (Extra-Low Interstitials) alloy manufactured by Laser-Powder Bed Fusion (L-PBF) using virgin powder (Cycle 1/C1 sample) and reused powder feedstock after up to 34 cycles (Cycle 34/C34 sample) of manufacturing. The effect of powder reuse is also evaluated for anodizing and Flash-PEO-coated specimens in Harrison’s (25 °C) and Hanks’ solutions (37 °C), representing simulated atmospheric precipitation and physiological conditions, respectively. Specimens were characterized using common metallographic techniques, X-ray diffraction, scanning electron microscopy and optical profilometry. Corrosion resistance was evaluated using cyclic potentiodynamic polarization (PDP) tests. The oxygen content in the Ti-6Al-4V reaches 0.14 wt.% after 34 cycles (C34) of powder reuse, enhancing its passivity in both Harrison’s and Hanks’ solutions. Both virgin and reused powder builds are susceptible to localized corrosion in Hanks’ solution at potentials above 1.75 V. Melt pool borders are thought to be the preferential sites for localized corrosion, as indicated by Volta potential measurements (ΔV = 100 mV). The number of cycles does not significantly affect the current–voltage responses for anodizing and flash-Plasma Electrolytic Oxidation (Flash-PEO) treatments, although anodizing is slightly more responsive to variations in surface roughness (i.e., real specimen area). Anodizing and Flash-PEO reduce the passive current density by nearly two orders of magnitude. Even after surface treatment, the alloy printed with reused powder revealed better passivity. Flash-PEO coatings yielded significant protection against localized corrosion. This unlocks Flash-PEO processing as a successful protection approach for AM biomedical components. Full article

Per- and polyfluoroalkyl substances (PFASs) in fluorinated firefighting wastewater (FFW), which are difficult to remediate using conventional technologies, represent a critical environmental hazard due to the extreme persistence and bioaccumulation potential of soil–groundwater systems. Niobium-supported boron-doped diamond (BDD) anodes were synthesized by microwave plasma chemical vapor deposition, and their performance in the electrochemical advanced oxidation processes (EAOPs) of FFW were systematically investigated. Under optimized conditions (100 mM Na₂SO₄ electrolyte with 100 mM peroxymonosulfate (PMS), current density of 33.3 mA/cm², pH = 6), the BDD anode achieved near-complete mineralization, with 92.5% total organic carbon (TOC) removal and significant defluorination (77.5% F⁻ release) within 240 min in simulated FFW-contaminated groundwater. For FFW-contaminated soil remediation, 90.2% TOC removal and 41.6% defluorination were achieved after 720 min under optimal treatment (water-to-soil ratio of 20:1). Quenching experiments and electron paramagnetic resonance (EPR) tests revealed that hydroxyl radicals (·OH) and singlet oxygen (¹O₂) were the predominant reactive species. Liquid chromatography–mass spectrometry/mass spectrometry (LC-MS/MS) analysis indicated that PFASs were removed by shortened carbon chains, ultimately mineralizing to CO₂ and F⁻. Toxicity assessment using Vibrio fischeri luminescence demonstrated a reduction in toxicity (from 99.8% to 20.9%), confirming the effective detoxification of BDD-based EAOPs. This work establishes BDD-based EAOPs as a promising technology for eliminating PFASs in groundwater and soil, offering theoretical insights into EAOPs and engineering solutions for PFAS remediation. Full article

Creeping bentgrass (Agrostis stolonifera), a widely used cool-season turfgrass, is highly susceptible to heat stress, which severely impairs its growth and physiological functions. In this study, two cultivars with contrasting heat tolerance, the heat-tolerant 13M and the heat-sensitive Seaside II (SII), were pretreated with diethyl aminoethyl hexanoate (DA-6) or distilled water and then exposed to either normal temperature or heat-stress conditions. Physiological traits and lipidomics were analyzed to investigate the regulatory role of DA-6 in lipid remodeling under high-temperature stress. Results showed that exogenous DA-6 application significantly mitigated physiological damage in both genotypes under heat stress. Under heat stress, compared with their corresponding untreated plants, DA-6 pretreatment increased the Fv/Fm by 15% in 13M and by 33% in SII; for the PI_ABS, DA-6 pretreatment increased it by 32% in 13M and by 55% in SII; for electrolyte leakage, DA-6 pretreatment reduced it by 24% in 13M and by 11% in SII. The analysis of lipidomics found that heat stress significantly reduced the accumulation of total lipids, phospholipids (PLs), glycolipids (GLs), and sphingolipids (SLs) in two genotypes, but under heat stress, 13M maintained significantly higher content of these lipids than SII. Exogenous DA-6 application significantly alleviated the heat-induced decline in photosynthesis-related glycolipids in SII. Specifically, MGDG, DGDG, and SQDG increased by 186%, 85%, and 32% in heat-stressed SII + DA-6, respectively, relative to heat-stressed SII without DA-6 pretreatment. In addition, DA-6 treatment also alleviated the heat-induced reduction in chloroplast- and mitochondria-associated lipids, including PG, LPG, and CL, in both genotypes. For heat-stressed 13M + DA-6, these lipids increased by 20%, 114%, and 22%, respectively, compared with heat-stressed 13M without DA-6 pretreatment; for heat-stressed SII + DA-6, they increased by 141%, 76%, and 184%, respectively, compared with heat-stressed SII without DA-6 pretreatment. These changes may contribute to improved stability of chloroplasts and mitochondria under heat stress. Furthermore, DA-6 application significantly promoted the accumulation of PC, PE, LPC, LPE, Cer, CerP, and Hex3Cer in both genotypes under heat stress. For 13M, the increases ranged from 18% to 120%; for SII, from 44% to 254%. In heat-stressed SII + DA-6 only, DA-6 also increased PA, PS, MLCL, DLCL, Hex1Cer, and Hex2Cer by 82%, 45%, 84%, 59%, 53%, and 41%, respectively, relative to heat-stressed SII without DA-6 pretreatment. These PLs and SLs are essential for maintaining plasma membrane integrity and mediating stress signal transduction. In addition, the application of DA-6 significantly reduced the heat-induced increase in unsaturation levels of total lipids in both genotypes, indicating that the DA-6 improved lipid saturation levels to better adapt to heat stress. Current findings demonstrated that the DA-6 application improved heat tolerance of creeping bentgrass associated with its regulation of lipid remodeling. Future investigations incorporating multi-omics approaches could comprehensively dissect the DA-6-induced signaling pathways and regulatory networks underlying heat-stress response in cool-season grass species. Full article

This review presents recent results focused on immobilization of zeolites onto inexpensive aluminum substrate using plasma electrolytic oxidation (PEO) processing in various electrolyte solutions applying different electrical regimes. PEO is recognized as a useful technique for the formation of oxide coatings with photocatalytic properties on various metals and alloys. Thin film photocatalysts are more practical than powder/nanoparticle photocatalysts because the photocatalyst does not need to be filtered/separated after the wastewater degradation treatment, which is an expensive and time-consuming process. Addition of zeolites to supporting electrolyte solutions influences structural, morphological and chemical properties of formed oxide coatings. Furthermore, introduction of zeolites loaded with cerium through an ion-exchange procedure is investigated. It is shown that the addition of both parent zeolites and Ce-exchanged zeolites is beneficial for photocatalytic decomposition of model organic pollutant (methyl orange). The most promising results are obtained under ultra-low duty cycle electrical conditions with Ce-exchanged 13X zeolite added to the electrolyte, where about 60% of the model organic pollutant is decomposed during 6 h of treatment under simulated sunlight irradiation (16,000 lx) for 3 cm² surface area of sample exposed to irradiation. Full article

The plasma electrolytic oxidation (PEO) of Zirlo alloy was carried out in a phosphate electrolyte with CaNa₂(EDTA) as an additive (0–15 g/L) to improve its corrosion and wear resistance. The PEO behavior, microstructure, phase composition, and performance of coatings were characterized as a function of the concentration of the additive. The results indicate that the addition of CaNa₂(EDTA) promotes coating growth and improves the coating structure and phase composition. When the additive concentration is 5–10 g/L, the coating shows an improved thickness, and denser microstructure. The coatings consist of m-ZrO₂ and t-ZrO₂ as the main crystalline phases, as well as amorphous materials with Ca and P. The t-ZrO₂ phase content rises sharply when CaNa₂(EDTA) is added into the electrolyte (81.3% t-ZrO₂ is obtained under the condition with 10 g/L CaNa₂(EDTA)). Potentiodynamic polarization tests demonstrate that PEO treatment significantly enhances the corrosion resistance of Zirlo alloy. Under the condition of 5 g/L CaNa₂(EDTA), the corrosion current density of the coating decreases by two orders of magnitude compared to the substrate, achieving the best corrosion resistance. Friction and wear tests also show that the coating obtained at 5 g/L CaNa₂(EDTA) exhibits the shallowest wear scar and the lowest wear rate, demonstrating optimal wear resistance. This study shows the novelty of obtaining high-quality PEO coatings on Zirlo alloy based on Ca and P incorporation. Full article

Myo-inositol (MI) is recognized as a potential stress regulator capable of alleviating abiotic stress. The objective of this study is to analyze the role of MI in the salt stress response of Daucus carota L. and its potential mechanisms. “Hongxin Qicun” carrot seedlings were subjected to five treatments: control; salt stress (50 mM NaCl); and salt stress combined with 50, 100, or 200 μM of MI. Through an integrated approach combining physiological assays, non-invasive micro-test technology (NMT), and gene expression profiling, we found that salt stress severely inhibited seedling growth, disrupted K⁺/Na⁺ homeostasis, and triggered excessive H₂O₂ accumulation. Exogenous MI application mitigated these salt-induced damages, with 100 μM MI exerting the optimal effect. MI enhanced Na⁺ efflux and reduced K⁺ efflux in carrot roots under salt stress. Inhibitor experiments indicated that MI-promoted Na⁺ efflux relies on active transport via the plasma membrane (PM) Na⁺/H⁺ antiporter system, and qRT-PCR analysis showed that this response was accompanied by the upregulation of DcSOS1. Furthermore, MI contributes to K⁺ homeostasis by synergistically modulating PM H⁺-ATPase and high-affinity potassium transporters. The established proton gradient helps reduce salt-induced K⁺ loss through depolarization-activated potassium channels and non-selective cation channels. MI treatment decreased electrolyte leakage, malondialdehyde content, and H₂O₂ accumulation by enhancing the activities of the plant antioxidant defense system. Meanwhile, MI upregulated the expression of myo-inositol oxygenase (DcMIOXs) genes, which may contribute to osmotic balance maintenance and facilitate ROS scavenging. In conclusion, exogenous MI alleviates salt-induced physiological disorders in Daucus carota L. by coordinately regulating K⁺/Na⁺ and ROS homeostasis, with 100 μM identified as the optimal concentration for this effect. Full article

The impending Euro 7 regulation will impose strict limits on brake particulate matter (PM) emissions from new light-duty vehicles, driving manufacturers to explore alternative rotor materials and/or surface treatments. This paper evaluates the friction and wear emission performance of both a laser-clad grey cast iron (GCI) rotor surface and a plasma electrolytic oxidation (PEO) treated aluminium surface compared to that of an uncoated GCI. Tests were conducted on a small-scale tribometer rig, which was specially adapted to measure airborne emissions while emulating the standard Worldwide harmonised Light vehicle Test Procedure (WLTP). The laser-clad coating was applied via extreme high-speed laser cladding to form an initial 430 L stainless steel layer, followed by a topcoat of 80/20 vol% 430L steel/TiC, both layers being c.100 micron thick. The PEO treatment applies a c.50 micron alumina coating to both a wrought and cast alloy, the latter being more suitable for the manufacture of full-size vented brake rotors. Results show that all rotor materials achieved a satisfactory coefficient of friction (CoF) against suitable low-metallic pad material, although the CoF for the wrought PEO-Al alloy was significantly higher at c.0.65 compared with c.0.50 for the other materials. The gravimetric wear of all the coated rotor surfaces after 8 WLTP cycles was almost undetectable, and pad wear was also significantly reduced. This improved wear resistance led to significant reductions in PM emissions, with the PM10 levels of the uncoated GCI reduced by around 75% for the laser-clad GCI and PEO wrought Al alloy, and by about 60% for the PEO cast Al alloy. When extrapolated to a full-sized passenger vehicle, the results indicated that both the laser-clad GCI and PEO-treated surfaces have the potential to meet the current Euro 7 emissions targets. Full article

This study analyses the effect of electrolytic plasma treatment on improving the wear resistance of 30CrMnSi steel used under conditions of high abrasive and impact-abrasive loads. The samples were processed using various technological regimes, namely electrolytic plasma quenching, nitriding, nitrocarburising, and carburising. A range of analytical methods were employed to comprehensively characterise the structure, phase composition, and mechanical properties, including SEM/EDS, XRD, and microhardness testing. The tribological properties of the materials were evaluated using a TRB³ tribometer, and abrasive and impact-abrasive wear tests were performed in accordance with GOST 23.208–79 and GOST 23.207–79 standards. The results show that electrolytic plasma treatment leads to the formation of diffusion layers with a thickness of 50–150 μm, accompanied by the formation of carbide, nitride, and carbonitride phases (Fe₄C, Fe₇C₃, Fe₄N, Fe₂N, Fe₃(CN)). This process results in a significant increase in surface hardness (up to 610–930 HV) and improved wear resistance. The study indicates that electrolytic plasma nitrocarburising provides a favourable combination of hardness and tribological behaviour, leading to a low friction coefficient (0.25–0.35) and enhanced resistance to abrasive and impact-abrasive wear. The obtained results demonstrate the potential of this technology for improving the performance of components made of 30CrMnSi steel operating under severe wear conditions. Full article

The development of high-performance solid-state energy storage devices is constrained by the limited ionic conductivity of gel electrolytes. To address this challenge, an inductively coupled nitrogen plasma (ICP) surface modification strategy was applied to poly(vinyl alcohol)–potassium hydroxide (PVA–KOH) gel electrolytes. The optimal plasma treatment parameters (150 W, 20 s) were identified based on ionic conductivity measurements. Comprehensive characterization confirmed that plasma treatment effectively introduced nitrogen-containing polar functional groups on the gel surface, induced surface nitrogen doping, increased surface roughness, and disrupted the hydrogen bond network. These synergistic microstructural modifications and chemical modifications increased interfacial polarity and facilitated ion transport, resulting in a 26% enhancement in the ionic conductivity compared with the pristine gel. Solid-state supercapacitors fabricated with the optimized gel electrolyte exhibits improved energy density, enhanced rate capability, and reduced interfacial impedance. These findings demonstrate that nitrogen-induced ICP treatment is an effective surface engineering strategy for improving gel electrolyte performance and advancing solid-state supercapacitor technologies. Full article

The intrinsic limitations of Ti₃C₂T_x electrodes, specifically low interfacial charge-transfer efficiency and structural degradation in strongly acidic environments, hinder their performance in high-rate aqueous supercapacitors. Herein, we report a synergistic strategy combining nitrogen plasma surface engineering with a redox-active ascorbic acid electrolyte to optimize the electrode/electrolyte interfacial kinetics. By systematic investigation, the Ti₃C₂T_x supercapacitor obtained by a 10-min plasma duration (N10P-AA) achieved the optimal balance between activating surface sites and preserving the conductive Ti–C framework integrity. The ascorbic acid electrolyte broadened the potential window to approximately 0.7 V, and N10P-AA exhibited the lowest charge-transfer impedance and superior rate capability, retaining a relatively high Coulombic efficiency (>72%) even at a high scan rate of 10,000 mV·s⁻¹. The EIS results and kinetics analysis (b values) confirmed that the moderate plasma activation effectively promoted more surface-dominated charge storage kinetics and mitigated diffusion limitation, consistent with reduced charge-transfer resistance and a smaller Warburg slope. The XPS results revealed that the 10-min treatment suppressed detrimental oxidation during cyclings and facilitated the formation of electrochemically favorable hydroxylated surface functional groups. This work demonstrates a feasible surface electrolyte co-engineering strategy for modulating the interfacial behavior of MXene, which is of great significance for future high-efficiency aqueous electrochemical energy storage and potential biosensing applications. Full article

This article presents a comparative study of mechanical properties and stress corrosion cracking (SCC) resistance of bare AW-5083 aluminum alloy and the same alloy coated by plasma electrolytic oxidation (PEO). Although Al–Mg alloys of the 5XXX series have been extensively studied with respect to SCC behavior, data concerning their performance after PEO treatment under mechanical loading in chloride-containing environments remain scarce. Prior to SCC testing, potentiodynamic polarization measurements were performed to assess the barrier properties of the PEO coating against general corrosion. The results demonstrate that the PEO coating significantly modifies the electrochemical response of the alloy and improves its resistance to corrosion processes in the presence of chloride ions. SCC tests revealed that the application of the PEO coating leads to enhanced resistance to stress-assisted degradation of the AW-5083 alloy, while distinct features of coating cracking under tensile loading were observed and discussed. The study provides new experimental insight into the combined mechanical and electrochemical behavior of PEO-coated AW-5083 alloy exposed to chloride environments. Full article

This study investigates the effect of electrolytic-plasma hardening time on the microstructure formation, hardness distribution, and corrosion behavior of grade 45 structural steel. The treatment was performed in a 15% aqueous sodium carbonate (Na₂CO₃) solution at an applied voltage of 300 V for different holding times (8, 10, and 12 s). Scanning electron microscopy and X-ray diffraction analyses revealed that increasing the EPH duration promotes the formation of a more uniform martensitic layer and reduces the amount of residual cementite. Microhardness measurements showed an increase in surface hardness from 190 HV for the untreated steel to 770 HV after the longest treatment. The cross-sectional hardness profile indicated the presence of a thin decarburized sublayer and a zone of maximum hardness corresponding to the martensitic structure. Potentiodynamic polarization tests in a 0.5 M NaCl solution showed a slight increase in corrosion current density after treatment; however, the corrosion rate remained within the range of 0.19–0.45 mm year⁻¹, confirming the satisfactory corrosion resistance of the hardened layer. The results demonstrate that controlling the EPH duration allows for optimizing the balance between enhanced hardness and maintained corrosion resistance of grade 45 steel. Full article

This study focuses on surface modification of aluminum alloys (Al–Si) with high silicon content using plasma electrolytic oxidation (PEO). The influence of Al₂O₃ and SiO₂ particles, introduced both separately and in combination, into a sodium aluminate-based electrolyte during high-frequency treatment (2000 Hz). Examination of surface and cross-sections using a scanning electron microscope SEM showed an increase in the compactness of the coating when Al₂O₃ particles were introduced. The addition of SiO₂ particles tended to promote a smoother surface and a slight reduction in the porosity and defect density. However, when these particles are added together, especially at high concentrations, an increase in structural defects and crack formation is observed. X-ray diffraction analysis revealed that the γ-Al₂O₃ phase was present in all coatings. In the samples with Al₂O₃ addition, the α-Al₂O₃ diffraction signal became stronger compared with the other coatings. Tribological tests revealed that the addition of Al₂O₃ particles significantly improved wear resistance, while the introduction of SiO₂ particles contributed to the stabilization of the friction coefficient. Thus, Al₂O₃ particles were the most effective in enhancing the mechanical properties of the coating. Full article

In this work, the effect of preliminary mechanical surface treatment on the kinetics of formation, phase composition, and functional properties of the nitrided layer during electrolytic-plasma nitriding (EPN) of austenitic stainless steel 12Kh18N10T (AISI 321) was investigated. In contrast to traditional approaches, for the first time, this work establishes a direct correlation between the degree of surface deformation induced by shot peening and the formation of the expanded austenite (γN) phase under low-temperature plasma conditions. Quantitative X-ray phase analysis revealed a lattice parameter expansion of Δa/a₀ ≈ 1.4–1.8% and a gradual transformation of γ-Fe → γN without the formation of CrN nitrides at moderate intensity of preliminary treatment. According to SEM/EDS data and microhardness profiles, a multilayer structure was formed, consisting of a thin surface film of CrN/Fe₄N, a developed γN zone with a thickness of 12–15 µm, and a stable austenitic γ-Fe matrix. The surface microhardness increases to 880 ± 20 HV, while the friction coefficient decreases to 0.35–0.40, corresponding to a wear reduction of approximately 55% compared to the initial steel. The results provide a mechanistic understanding of nitrogen diffusion through defect-enriched subsurface layers and show that optimal preliminary deformation (d = 6 mm, v = 40 Hz, t = 20 min) promotes controlled formation of the γN phase with minimal lattice instability. The proposed combined approach—shot peening + EPN—is an effective method for producing wear- and corrosion-resistant surfaces of austenitic steels under atmospheric plasma conditions. Full article

Background and Objectives: Currently, the development of local drug delivery systems for the treatment of cancer patients is a pressing issue. Such systems allow for the targeted delivery of anticancer drugs directly to the tumor site, ensuring prolonged drug release or reducing the risk of recurrence after tumor removal, minimizing the impact on healthy tissues and thereby reducing the overall toxic load on the body. This work is devoted to evaluating the prospects of using scaffolds based on low-modulus titanium Ti-15Mo alloy with a biomimetic coating as a platform for the local administration of the cytostatic drug cisplatin into the patient’s body. Methods: Porous coatings were obtained by plasma electrolytic oxidation in an aqueous solution of sodium phosphate and calcium acetate with the addition of various components. The influence of coating parameters on the corrosion resistance of samples and on the antiproliferative effect of cisplatin-loaded scaffolds was evaluated. Human K562 hemoblastosis, HT116 intestinal cancer, and SKOV3 ovarian cancer cell lines were used as cell models. Results: It was shown that the addition of sodium phosphate (the PS type electrolyte) provides the formation of a coating with a developed system of interconnected pores characterized by an attractive combination of parameters: high porosity (17%), high pore size (3.9 μm), and considerable thickness (17.4 μm). This coating demonstrated the best corrosion resistance in a Ringer solution as compared to the other tested states. In addition, the PS coating loaded with cisplatin exhibited a pronounced cytotoxic effect on cancer cells. This effect was attributed to its ability to fix cisplatin on the surface, which slows down its release into the extracellular environment, increasing the time of its action, thereby contributing to a more effective (by more than 3 times) suppression of tumor cell proliferation compared to the action of the standard form of the drug in the form of a solution when changing the growth medium and subsequent incubation for 48 h. Conclusions: PS scaffolds made of low-modulus titanium alloy Ti-15Mo with a biomimetic surface in an electrolyte based on an aqueous solution of sodium phosphate and calcium acetate with the addition of sodium silicate can be used as an advanced platform for the local delivery of the cytostatic drug cisplatin, which makes them promising for application in orthopedic oncology. Full article