Search Results (713)

This study developed surface-functionalized polylactic acid (PLA) films by depositing electrospun gelatin/chitosan (GE/CH) nanofibrous coatings formulated with and without bioactive phenolic compounds (curcumin and anthocyanin). Evaluating various polymer blending ratios and operational parameters revealed that a GE:CH ratio of 7:3 (v/v), processed at an applied voltage of 25 kV and a collector speed of 300 rpm, provided the most stable electrospinning behavior among those tested, yielding a uniform nanoscale fibrillar network. The deposition of this selected GE/CH layer onto the PLA substrate significantly improved the composite bilayer film’s tensile strength and oxygen barrier properties, although it increased macroscopic opacity. Furthermore, active coatings containing 0.25% and 0.50% (w/w) curcumin or anthocyanin were successfully processed. This 0.50% level was the maximum concentration quantitatively evaluated in the present study, as preliminary observations suggested poorer processability at higher concentrations, which induced premature gelation and needle clogging. While interactions (mostly non-covalent physical interactions) associated with the phenolic compounds synergistically reinforced the mechanical rigidity and reduced the water vapor permeability of the bilayer films, the macroscopic bioactive functionality was limited. The low loading concentrations, coupled with severe optical masking and restricted aqueous extraction, resulted in moderate antioxidant activity (10.31–30.46% DPPH radical inhibition) and no visually detectable halochromic (pH-responsive) color changes. Overall, these findings highlight a significant functional trade-off in the design of active coatings, where structural and mass transport barrier enhancements are achieved, but macroscopic bioactive functionality is constrained, underscoring the necessity for advanced encapsulation strategies in future developments. Full article

We present a brief review that highlights the importance of III-Nitride semiconductor compounds according to their structural, compositional, morphological, and optical properties, which have significant applications in new semiconductor devices and play a fundamental role in modern electronic and optoelectronic technologies. The importance of sputtering as a viable alternative for obtaining III-Nitride semiconductor compounds is discussed. This is due to its versatility, cost, ease of handling, and advantages provided by the physics of its operation in obtaining thin films compared to techniques such as metal–organic chemical vapor deposition (MOCVD), atomic layer deposition (ALD), and molecular beam epitaxy (MBE). The physics of the sputtering method is briefly and clearly described, including magnetron configurations, plasma generation, energy dependence of sputtering, reactive sputtering, hysteresis effects, target types, and the importance of temperature and working distance between the substrate and target. In addition, the review of the literature on the application of sputtering for obtaining III-Nitride semiconductor compounds is presented. Furthermore, this review also highlights the future of sputtering, which is moving towards high-power pulsation, atomic-level precision, and AI-driven automation due to the miniaturization of electronics, advances in green technology, and innovations in plasma control to increase film density and reduce target material loss. Full article

Among the vast array of technologies available for surface modification of materials, sputtering emerges as one of the most versatile methods through coating deposition. Included in the family of physical vapor deposition (PVD) techniques, sputtering allows the production of coatings with a great variety of characteristics, based on a bottom-up approach that forms coatings from individual species (atoms or ions). This versatility is achieved by controlling: (i) the layer architecture, from monolithic to multilayers, (ii) the structures, from amorphous to nanocrystalline or nanocomposite, until highly crystallized, including epitaxial; (iii) the morphologies, from very porous through columnar or zig-zag to very dense and featureless; (iv) the chemical composition, allowing the deposition of metallic, polymeric, ceramic or composite materials types. In this paper, after a brief introduction of sputtering as a deposition technology, we will review the application of sputtering for depositing protective coatings to which an extra functionality is provided: (a) aesthetic color; (b) high-temperature lubrication; and (c) temperature sensing ability. Full article

W-modified TiAlN coatings were developed as hydrogen permeation barrier coatings for magnetic materials. TiAlN and TiAlN-W coatings with comparable thicknesses of approximately 1.5 μm were deposited on Fe and NdFeB substrates by physical vapor deposition. GIXRD and SEM results showed that W modification was associated with a change from weakly crystalline, columnar TiAlN to a more compact, low-crystallinity W-modified Ti–Al–N coating with amorphous/nanocrystalline features inferred from the broad diffraction response. XPS analysis identified low-valence W-related species, such as W–N/Wⁿ⁺-related bonding, together with overlapping Ti 3p/W–O_x contributions and surface oxide/oxynitride species, indicating a modified surface and near-surface chemical environment. Electrochemical hydrogen permeation tests on Fe substrates showed that TiAlN reduced the steady-state current density from 2.54 ± 0.86 to 0.55 ± 0.08 μA cm⁻², corresponding to a permeation reduction factor of 4.68 ± 0.16. In contrast, TiAlN-W showed no obvious hydrogen breakthrough during the 15,000 s test period, and the current density remained below the practical detection limit of 0.01 μA cm⁻², giving a lower-bound permeation reduction factor of >250. In high-pressure H₂ exposure tests, the TiAlN-W-coated NdFeB sample remained macroscopically intact after exposure to 5 MPa H₂ at 23 °C for 24 h, whereas the uncoated and TiAlN-coated samples were pulverized. The markedly improved hydrogen permeation resistance is associated primarily with the more compact cross-sectional morphology and W-modified coating structure. Full article

This study investigates the tribological performance of chromium nitride (CrN)-coated polyether ether ketone (PEEK) polymers. CrN coating was deposited by physical vapor deposition (PVD) onto two commercially available substrates: neat PEEK and a modified PEEK. The suitability of the coated substrates for tribological applications was evaluated using ball-on-disc tests against stainless-steel (SS) counterparts. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) confirmed the high thermal stability of the PEEK substrates, ensuring compatibility with low-temperature coating deposition. Microstructural analysis revealed dense and continuous CrN coatings with an average thickness of ~1.5 µm on both substrates. Tribological results of selected PEEK-based polymers showed that under the applied load of 2 N, uncoated PEEK substrates exhibited lower coefficients of friction (COFs) and smoother wear tracks compared with coated samples. In contrast, under the applied load of 4 N, CrN-coated PEEK substrates demonstrated reduced friction and improved stability relative to uncoated PEEK. This behavior is attributed to load-induced tribo-oxidation and the formation of a chromium-oxide-rich tribolayer that stabilized the sliding interface and suppressed adhesive wear. Overall, the results demonstrate that CrN coatings significantly enhance the load-bearing capacity and tribological performance of selected PEEK substrates under applied load of 4 N, highlighting their potential for advanced lightweight engineering applications requiring improved wear resistance. Full article

Functional coatings have evolved from their early role as passive barriers against corrosion and wear into engineered interfaces that actively mediate the interaction between a bulk material and its environment. This review traces the evolution of coating technologies from traditional macroscopic protective layers to nanoscale and multifunctional systems, and finally to smart and stimuli-responsive architectures. Advanced deposition and surface modification techniques are examined, including atomic layer deposition, physical vapor deposition, electrochemical and sol–gel approaches. The discussion is structured around two complementary application domains: extreme energy environments, focusing on coatings developed for advanced nuclear systems, and modern medical implants, including bioactive and antimicrobial surfaces and drug-delivery interfaces. The review highlights that, despite the differences between reactor and biomedical environments, both sectors share a common set of design principles and challenges, including interfacial adhesion, mechanical durability, the dual role of nanostructuring, and the trade-off between architectural complexity and operational reliability. Long-term stability, scalability, and standardized validation remain key barriers to deployment, while data-driven design and the deliberate integration of multiple functions emerge as the principal directions for future development. Full article

To investigate the influence of particle size on the erosion damage behavior and failure mechanisms of thermal barrier coatings (TBCs) in a simulated aero-engine erosion environment, erosion tests were conducted using Al₂O₃ particles of different sizes (65 μm, 120 μm, and 175 μm) under a nominal gas-flow condition of Mach 0.4 at 1150 °C with custom-built multi-factor coupled erosion test equipment. TBCs were prepared using electron beam physical vapor deposition (EB-PVD). By combining macroscopic/microscopic morphology, composition, white-light interferometry, and Raman residual stress testing, the damage evolution and failure behavior of TBCs under different particle size conditions were analyzed. The results indicate that particle size has a significant effect on the erosion behavior of thermal barrier coatings. Under erosion conditions involving 65, 120, and 175 μm particles, the erosion rates were 10.83, 4.19, and 2.05 g/kg, with corresponding coating lifetimes of approximately 3, 12, and 22 h. As particle size increases, the erosion rate decreases and the coating lifetime increases. Under small 65 μm particles, the coating exhibits high-frequency continuous micro-cutting. The ceramic layer rapidly thins, leading to localized penetration. Under erosion by 120 μm particles, the coating exhibits a composite damage mechanism involving cutting, compaction, and brittle fracture. Under large-particle impacts of 175 μm, the damage mechanism is dominated by localized brittle fracture and spalling induced by high-energy impacts. Although the single-impact energy of large-particle impacts is higher, the lower particle number density results in a discrete distribution of damage zones, leading to a lower material removal rate. The Raman test results further indicate that, after 2 h of erosion, the differences in residual stress in the TGO layer were relatively small across different particle size conditions, suggesting that the early degradation process of the coating is primarily controlled by the mechanical removal of the ceramic surface layer rather than by the evolution of TGO stress. No statistically significant difference in TGO residual stress was observed among different particle sizes after 2 h of erosion (p > 0.05). Not only is the erosion life of EB-PVD YSZ TBCs is influenced by the impact energy of individual particles, but more importantly, it is also closely related to particle number density, impact frequency, and the spatial distribution of damage. Full article

Transition metal oxides constitute an important materials platform for chromic phenomena because their optical response is strongly coupled to the changes in electronic structure, phase state, carrier concentration, and defect chemistry. This review discusses selected transition metal oxide thin films, with emphasis on VO₂ and other vanadium oxides, WO₃, NiO, and TiO₂. The review summarizes the structural and electronic characteristics of these representative oxide systems and highlights the role of phase composition, crystal structure, oxygen non-stoichiometry, and defect chemistry in determining their optical response. The main thin film preparation routes, including pulsed laser deposition, magnetron sputtering, sol–gel and aerosol spray methods, atomic layer deposition, chemical vapor deposition, electrochemical routes, and molecular beam epitaxy, are reviewed with respect their influence on obtained thin films. Particular attention is given to applications in thermochromic VO₂-and electrochromic WO₃/NiO-based smart windows, and transition metal oxide-based gasochromic hydrogen sensors. Key challenges related to transition temperature tuning, luminous transmittance, solar modulation, optical contrast, cycling stability, ion transport and large-area integration are also discussed. Overall this review provides a comparative overview of selected transition metal oxide thin films by connecting material chemistry and physics, thin film preparation technology and functionality. Full article

In our day-to-day lives, we are regularly exposed to a wide spectrum of dangerous gases. Their origins vary, ranging from industrial activities to objects found within our very homes. Naturally, there is an interest in developing cost-efficient and durable devices that can successfully track these gases within our environment. One such candidate is represented by chemoresistive gas sensors based on metal oxides. This is due to their simple architecture and the possibility of scaling down their size, making them valid contenders for future advancements in portable gas sensors. This review focuses on chemoresistive gas sensors that have been obtained through different Physical Vapor Deposition (PVD) methods, which are easily scalable for potential technological transfer towards commercialization or are already exploited at the industrial level, and how varying different deposition parameters impacts the structure of the active material, thus modifying the gas sensing properties of the device. In this review, we report results obtained for different metal oxides: WO₃, ZnO, CeO₂, TiO₂, NiO, and SnO₂. The main findings of these studies revealed that the sensor’s response was highly impacted by oxygen deficiencies within the deposited material, the specific surface area, and the thickness of the film. Moreover, this study also delves into different strategies of functionalization that result in improved gas sensing properties. Thus, we herein report how tailoring functional properties modifies the gas sensing performance of different metal oxides. Full article

Two-dimensional black phosphorus (2D BP) has emerged as one of the most promising two-dimensional semiconductors for next-generation micro and nanoelectronics beyond Moore’s Law. It is distinguished by its unique combination of a layer dependent direct bandgap, broadband photoresponse, and pronounced in-plane anisotropy, addressing key intrinsic limitations that have hindered the widespread application of graphene and conventional transition metal dichalcogenides (TMDCs). This review provides a systematic and comprehensive overview of recent advances in the controllable fabrication of 2D BP and its applications in transistors and photodetectors. We first elucidate its crystal lattice structure and fundamental physical properties, then categorize and summarize synthesis strategies based on production scale ranging from small scale methods (e.g., mechanical exfoliation and solution based exfoliation) to large scale methods (e.g., Chemical Vapor Deposition (CVD) and Pulsed Laser Deposition (PLD)), with a particular focus on recent advances in high-speed field-effect transistors and broadband photodetectors. In summary, the key to achieving large-scale controllable synthesis lies in addressing the challenges of high-temperature oxidation of black phosphorus and the uncontrollable diffusion of phosphorus sources. In the future, industrial applications are expected to be realized through CVD based regulation of phosphorus sources, low-temperature growth by PLD, and deep integration with silicon-based processes. Full article

High-entropy alloy (HEA) coatings exhibit enhanced chemical stability when doped with carbon, primarily due to the strong bonding between carbon and transition metals. Typical transition metals used in these coatings include Cr, Fe, Co, Ni, Cu, Ti, V, W, Nb, Ta, and Zr. Owing to their excellent chemical stability, HEA coatings are widely employed to protect component surfaces operating in highly corrosive environments. Against this backdrop, the present study investigates the effect of carbon doping introduced via methane gas flow during the physical vapor deposition of TiAlTaZrNb HEA coatings on corrosion resistance. The morphology and structure of the coatings were analyzed by field emission scanning electron microscopy, X-ray diffraction, and Raman spectroscopy. Corrosion protection and coating resistance were assessed through potentiodynamic polarization and electrochemical impedance spectroscopy. While increasing the methane flow resulted in an approximately 34% reduction in coating thickness, the overall coating resistance increased by one order of magnitude, reaching a maximum at a methane flow rate of 9 sccm, corresponding to the carbon solubility limit. This improvement was evidenced by a decrease in the corrosion rate from 8.02 × 10⁻² mm y⁻¹ for the uncoated H13 steel to 8.00 × 10⁻⁴ mm y⁻¹ for the HEA-coated samples. However, at higher methane flow rates, carbon precipitation and the formation of parallel microcracks contributed to an increase in corrosion rate. Full article

This study investigated porous materials based on cellulose acetate (CA), poly(lactic acid) (PLA), and their multilayer combinations fabricated by solution blow spinning (SBS) for potential food packaging applications. Single-layer neat polymers and multilayer structures (CA/PLA, CA/PLA/CA, and PLA/CA/PLA) were produced through sequential deposition, enabling control of layer arrangement while preserving high porosity. Attenuated total reflectance Fourier-transformed infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis showed negligible polymer interdiffusion or specific intermolecular interactions, indicating that layer integration occurs mainly through physical contact and void filling rather than molecular mixing. Scanning electron microscopy analysis revealed that cellulose acetate possesses a highly porous, interconnected structure, whereas poly(lactic acid) exhibits a predominantly fibrous morphology with clearly distinguishable layers in multilayer systems. Mechanical testing demonstrated that poly(lactic acid) mats had higher stiffness and tensile strength, while cellulose acetate films were more flexible and compliant. Multilayer systems showed complex tensile behavior characterized by interfacial failure and limited load transfer, indicating no synergistic mechanical reinforcement between layers. Water vapor permeability remained high and narrowly distributed for all configurations (890–920 g·m⁻²·day⁻¹), independent of layer sequence, reflecting the porous morphology. These values exceed those of conventional polymer packaging films, highlighting the suitability of the materials for breathable packaging. Overall, solution blow spinning enables scalable fabrication of biodegradable multilayer materials with tunable mechanical performance for sustainable food packaging applications requiring controlled moisture exchange. Full article

Surface engineering strongly influences the performance, reliability, and safety of medical and biomedical devices, yet failures often originate at interfaces rather than in bulk materials alone. This review addresses the fragmented evidence base linking coating selection, interphase design, qualification testing, advanced characterization, and data-driven durability analysis. The objective is to provide an integrative, failure-mode-based framework for implants, reusable instruments, inhalation systems, diagnostics, wearables, and implantable electronics. A narrative synthesis of the peer-reviewed literature in coatings, biomaterials, electrochemistry, reliability, standards, and materials informatics was conducted, with qualitative tables used only when protocols were too heterogeneous for numerical pooling. The review compares physical vapor deposition (PVD), chemical and plasma-enhanced chemical vapor deposition (CVD/PECVD), atomic layer deposition (ALD), sol–gel/organically modified silica (ORMOSIL) hybrids, plasma polymers, parylene, bioactive or antimicrobial surfaces, and electronic encapsulation strategies. The main finding is that no universally superior coating exists; reliable performance depends on matching architecture and characterization to the dominant failure pathway, substrate compliance, geometry, sterilization or physiologic exposure, and the standards-constrained endpoint. The review further shows how electrochemical diagnostics, interfacial mechanics, multiphysics models, survival/reliability statistics, and carefully governed AI workflows can be combined to support service-life prediction and decision-oriented qualification. Full article

Two-dimensional molybdenum disulfide (MoS₂) has emerged as a promising candidate for next-generation electronics and optoelectronics; however, its scalable synthesis with precise control over domain size and film continuity remains challenging. Herein, we report a physical vapor deposition (PVD)-assisted chemical vapor deposition (CVD) strategy for the controllable growth of high-quality monolayer MoS₂. By thermally evaporating an ultrathin (3 nm) MoO₃ precursor film, spontaneous post-deposition dewetting yields a porous honeycomb morphology that significantly enhances vapor–solid reaction kinetics during subsequent sulfurization. Crucially, by modulating the argon carrier gas flow rate to regulate the local sulfur chemical potential, we achieve distinct growth regimes: a high flow rate (70 sccm) suppresses nucleation density, enabling isolated triangular and hexagonal single crystals with lateral dimensions up to 500 μm, whereas a reduced flow rate (50 sccm) promotes high-density nucleation and coalescence into continuous centimeter-scale polycrystalline films. Comprehensive structural and optical characterizations, including atomic force microscopy, Raman spectroscopy, photoluminescence, and X-ray photoelectron spectroscopy, confirm that the synthesized MoS₂ exhibits prototypical monolayer thickness (~0.7 nm), well-defined local crystallinity and a direct bandgap emission at 1.84 eV. This work establishes a robust, scalable, and highly tunable route for synthesizing large-area 2D TMDs tailored for advanced device integration. Full article

This work presents advanced binder-free self-assembling Zn nanowire anodes synthesized by an easy-to-handle one-step low-pressure physical vapor deposition method. The morphology and structure of zinc nanowire networks are controlled and altered by the substrate temperature during deposition. Electrochemical performance of two types of Zn nanowire network samples of different morphology is studied in alkaline and mildly acidic aqueous electrolytes using cyclic voltammetry and electrochemical impedance spectroscopy techniques and compared to that of Zn foil electrodes. It is found that the morphology and structure of the Zn nanowire electrodes are directly related to their electrochemical performance and can be tuned for the type and concentration of the electrolyte to reach optimal electrochemical performance. The resulting binder-free self-assembled Zn nanowire anodes significantly outperform traditional Zn-based electrodes in both mild acidic and alkaline electrolytes, showing an areal capacitance of ~3.3 F/cm² and 3.5 F/cm² for acidic and alkaline electrolytes, respectively, and stability up to 1000 h of cycling in mild acidic electrolytes. These findings provide a pathway to fabricate and optimize binder-free zinc anodes for a variety of efficient and long-lasting aqueous zinc-based batteries and supercapacitors. Full article