Search Results (467)

Expanding the operating pressure range of hollow cathode glow discharge to the region of 0.01–0.1 Pa makes it possible to use the discharge plasma in a number of technological processes that were previously not feasible, because pressure always exceeded p = 1 Pa. Implantation of nitrogen ions by means of application of 40 kV pulses to a steel workpiece immersed in plasma at p < 0.1 Pa allows production of a 40 µm thick surface layer with hardness of 13 GPa exceeding by 6.5 times the hardness of the bulk and a decrease in the processing time by an order of magnitude. Nitriding a steel workpiece at p = 0.1 Pa allows a substantial increase in the nitriding rate. The use of a titanium workpiece as a discharge anode with surface area not exceeding a critical value allows it to melt due to heating to the melting point of 1670 °C by electrons accelerated in the positive anode fall of potential. Full article

The choice of brass as the substrate due to its widespread use in soft non-ferrous industrial components such as bearings and electrical connectors creates the primary basis of novelty in this study. While prior tribological studies on titanium aluminum nitride (TiAlN) coatings is primarily focused on hard substrates such as steel and WC–Co, this work addresses the research gap by presenting a systematic investigation of the combined influence of sputtering power and working pressure on TiAlN coatings deposited on brass. Application of TiAlN coatings on brass surfaces was accomplished using magnetron sputtering. Within the scope of this study, the influence of sputtering power and working pressure on the tribological and structural attributes of TiAlN films is evaluated. The analysis of surface morphology is carried out using scanning electron microscopy (SEM), while structural characteristics revealed a progressive increment in the intensity of the (103) and (107) peaks with variation in deposition parameters. An analysis was conducted to evaluate the tribological properties of the TiAlN coating using a pin-on-disk tribometer. The study involved varying the speeds, loads, and sliding lengths. The optimized condition achieved wear reduction as high as 22% compared to uncoated brass at a sliding distance of 785 m, which highlights the strong dependence of wear performance on deposition parameters. The wear rates of TiAlN-coated brass ranged between 1.03 × 10⁻³ and 5.87 × 10⁻⁴ mm³/Nm depending on parameters like load, sliding distance and speed. Conversely, TiAlN-coated brass pins prepared at varying power showed wear rates ranging from 1.83 × 10⁻⁴ to 5.87 × 10⁻⁴ mm³/Nm. These findings demonstrate that optimization of TiAlN coating parameters on brass can significantly enhance wear resistance, which ultimately improves the durability and performance of engineering components in tribological applications. Full article

With the increasing demands on energy efficiency and dynamic stability of modern combustion engines (e.g., TDI systems), conventional powder metallurgy materials are reaching their limits in terms of fatigue life and surface integrity. This scientific problem has led to the need to develop hybrid metal matrix (MMC) systems that use in situ hard phase formation. This study presents a comparative analysis of two real industrial components representing hybrid systems with a uniquely high content of titanium and vanadium (>1% by weight). The Ni-Mo-Ti system and the high-carbon C-Cu-Ti system were compared. The samples were processed by steam oxidation and plasma nitriding at 200 °C after sintering. The experimental methodology included chemical analysis on the Bruker Q2 ION 2 instrument, 10-point EDX analysis (Phenom), measurement of the apparent hardness of HV10 and dynamic ball-on-disc tribological tests at a load of 5.00 N supplemented by 3D profilometry. The results showed that the Ni-Mo-Ti system achieves higher hardness at functional edges (256 HV10) and three times higher resistance to deep penetration (11.46 μm vs. 34.67 μm) compared to the C-Cu-Ti system. Topographic analysis confirmed the positive role of porosity as a micro-reservoir for abrasion particles (negative Ssk). The study confirms that the nickel–molybdenum matrix ensures more efficient fixation of in situ generated TiC carbides, thus providing higher functional stability for automotive applications, which was verified by the non-destructive vibroacoustic diagnostics of Polytec PSV-500. Full article

Anterior cervical discectomy and fusion (ACDF) is one of the most commonly performed surgical procedures for the treatment of cervical degenerative disease, myelopathy, radiculopathy, and segmental instability. Although clinical outcomes are generally favorable, pseudarthrosis remains a relevant complication, with a reported incidence ranging from 5% to 20%. In a field with no yet clear main directions, this narrative review aims at giving the reader a broad picture and a wide analysis of the recent advances in cervical spinal fusion, with particular focus on biomaterials, intervertebral cage technologies, cervical spine biomechanics and imaging methods used for fusion assessment. The literature regarding quantitative imaging parameters and emerging applications of artificial intelligence (AI) is also reviewed. Current bone grafts include autologous grafts, allografts, xenografts and polymeric grafts, while the materials for the intervertebral cages comprehend titanium, polyetheretherketone and silicon nitride, with reported fusion rates distributed in a very large range. Computed tomography (CT) remains the standard imaging modality to assess whether fusion has occurred, due to its high spatial resolution. However, the lack of shared diagnostic criteria and the significant interobserver variability continue to limit its reliability. Quantitative parameters, such as Hounsfield Unit measurements and MRI-derived bone quality scores, may contribute to a more objective evaluation, although current evidence remains heterogeneous. In parallel, AI-based imaging analysis is showing promising results for quantitative assessment and longitudinal monitoring of bone fusion; however, large prospective clinical studies are still needed to confirm its clinical applicability. In conclusion, despite advances in surgical technologies and biomaterials, radiological assessment of cervical fusion still lacks universally accepted diagnostic standards. Future AI applications may improve diagnostic accuracy and reproducibility, promoting a more standardized approach in clinical practice. Full article

Chromium nitride (CrN) can be used as a coating material deposited via physical vapour deposition (PVD), thereby improving the corrosion and wear resistance of the substrate. However, this level of corrosion protection may not be sufficient in an aggressive corrosion environment. The coatings often contain intrinsic microstructural defects, such as microcraters, which can serve as pathways for the corrosive medium to reach the substrate, thereby initiating and promoting corrosion. In this study, the influence of parameters on the formation of a TiO₂ layer using the ALD technique was investigated. In particular, the work focused on assessing the effectiveness of the TiO₂ layer as a sealing barrier for CrN coatings (PVD) applied to austenitic 316L steel. The TiO₂ ALD coatings were produced at a constant temperature of 200 °C with a varying number of cycles, ranging from 200 to 1000 cycles. Structural investigations were carried out using scanning electron microscopy SEM and atomic force microscopy. Electrochemical properties were investigated using a potentiodynamic test and electrochemical impedance spectroscopy (EIS) in a 3.5% NaCl solution. SEM observations indicate that the morphology of the hybrid coatings is strongly influenced by the number of ALD cycles. The TiO₂ layer conformally reproduces the underlying PVD topography while progressively sealing the coating by filling intrinsic defects and discontinuities. Hybrid coatings (PVD/ALD) with titanium oxide deposited at 500 ALD cycles were found to have the best corrosion resistance. The polarisation resistance for these coatings was nearly four times higher than that of both the single PVD (CrN) coating and the uncoated stainless steel 316L substrate. At the same time, the corrosion current density was several times lower than that of the reference systems. The corrosion mechanisms were investigated by observing the surfaces of the samples after corrosion testing using SEM. Abrasion resistance tests using the pin-on-disc method and adhesion tests (scratch tests) were also performed, which showed that appropriate optimisation of the layer architecture in the PVD/ALD hybrid system significantly improves its tribological durability, interlayer stability, and adhesion to the substrate. Full article

Two-dimensional (2D) materials exhibit electronic and collective excitation properties that are highly sensitive to surface chemistry and thickness, requiring surface-sensitive characterization at low electron energies. Here, we investigate graphene, hexagonal boron nitride (h-BN), molybdenum disulfide (MoS₂), and titanium carbide (Ti₃C₂) MXene using an advanced home-built scanning low-energy electron microscopy system combined with time-of-flight electron spectroscopy (SLEEM/ToF). The system uniquely records electron energy-loss spectra (EELS) from transmitted electrons rather than from the reflected electrons used in conventional SLEEM. Compared with high-energy EELS, our low-energy ToF-EELS approach offers enhanced surface sensitivity and reduced beam-induced damage, enabling direct probing of π and π + σ plasmon excitations. Additionally, complementary techniques, including scanning transmission electron microscopy (STEM), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), were employed to characterize structural and chemical properties. EELS were acquired for all investigated 2D materials at electron landing energies of 500–1500 eV, and in the 5–50 eV range for selected materials, including graphene and MoS₂. Analysis of these spectra enabled determination of the average plasmon positions across the measured energy range for all studied materials. Furthermore, a quantitative determination of the inelastic mean free path (IMFP) was achieved for graphene in the 10–50 eV range, yielding a value of 1.9 ± 0.2 nm. These results demonstrate the potential of SLEEM–ToF for surface-sensitive analysis of 2D materials. Full article

Hydrogen embrittlement (HE) represents a critical degradation mechanism in carbon steel components operating in hydrogen-rich environments, such as those encountered in clean energy and petrochemical applications. This study evaluates the hydrogen permeation barrier performance of titanium nitride (TiN) nanostructured thin films deposited by High-Power Impulse Magnetron Sputtering (HiPIMS) on SAE 1020 carbon steel substrates. Electrochemical permeation measurements were performed using the Devanathan–Stachurski dual-cell methodology in accordance with ASTM G148 and ISO 17081 standards. Key hydrogen transport parameters quantified include the effective diffusion coefficient (D_eff), lag time (t_lag), and steady-state hydrogen oxidation current density. The TiN/carbon steel composite system exhibited t_lag = 570 s, D_eff = (2.68 ± 0.09) × 10⁻¹⁰ m² s⁻¹ and a steady-state hydrogen oxidation current density of 21.5 µA cm⁻², corresponding to a permeation reduction factor (PRF) of 2.32 and a barrier efficiency of η = 56.9%. The superior barrier performance is attributed to the dense, low-defect microstructure characteristic of HiPIMS deposition. These results validate HiPIMS-deposited TiN as a robust hydrogen diffusion barrier, with the established performance metrics providing quantitative benchmarks for the design of hydrogen-resistant coatings in energy applications. Full article

To address the issues of high cutting temperatures and severe tool wear during titanium alloy machining, this study proposes a hybrid surface modification strategy combining micro-textures and multicomponent titanium nitride (TiN)-based coatings on cemented carbide tools. Using YG8 cemented carbide as the substrate, micro-dimple textures were fabricated by fiber laser, and three coatings with different architectures (TiAlSiN, TiSiN/TiAlN, and TiSiN/TiAlSiN/TiAlN) were deposited via multi-arc ion plating technology. Based on a two-factor (texture diameter and texture spacing) and three-level orthogonal experiment, the evolution behaviors of surface morphology, phase composition, and mechanical properties of the textured multicomponent TiN-based coatings were systematically characterized and comparatively analyzed. The results reveal that: compared to the monolithic-structured TiAlSiN coating, the TiSiN/TiAlSiN/TiAlN and TiSiN/TiAlN composite coatings with multilayered composite structures can effectively relieve the residual stress inside the film–substrate system, and significantly suppress the phenomena of coating cracking and localized spallation caused by irregular protrusions of the recast layer at the micro-texture edges. X-ray diffraction (XRD) and crystallite size analyses indicate that the amorphous Si₃N₄ phase promoted by the Si element in the composite coatings effectively impedes the growth of TiN columnar crystals, achieving significant grain refinement. Mechanical property tests confirm that the existence of multicomponent composite interfaces effectively hinders dislocation movement. Among them, the textured TiSiN/TiAlSiN/TiAlN composite coating exhibits the optimal comprehensive performance; its microhardness, nanohardness, and H/E ratio (characterizing the resistance to plastic deformation) are increased by 17.94%, 8%, and approximately 45%, respectively, compared to those of the textured TiAlSiN coating. This study deeply elucidates the synergistic strengthening and toughening mechanisms between micro-texture parameters and the internal structures of the coatings, providing important theoretical guidance and experimental data support for the surface design of long-lifespan tools oriented towards the high-efficiency machining of titanium alloys. Full article

The development of multilayer coatings based on titanium carbides and nitrides remains one of the most active areas in materials science, owing to their ability to markedly enhance wear resistance and extend the service life of machine components. Particular interest is currently focused on tailoring conventional TiN/TiCN architectures through alloying metal additions. In this study, the tribological and mechanical performance of aluminum- and zirconium-doped TiN/TiCN multilayer coatings deposited by direct-current magnetron sputtering onto 41Cr4 steel was investigated. The morphology, elemental distribution, and phase constitution of the multilayer coatings were examined. It is shown that increasing the number of bilayers from two to four in TiN/TiCN–based multilayer coatings leads to improved tribomechanical characteristics. It was determined that zirconium provides a more pronounced beneficial effect than aluminum. The four-bilayer TiZrN/TiZrCN coating simultaneously exhibited the lowest coefficient of friction (0.11) and wear rate (10⁻⁶ mm³ m⁻¹ N⁻¹) at a hardness of 16.4 GPa. Full article

In this work, for the first time, we applied and determined the mechanical characteristics of protective coatings made of high-entropy alloy (TiZrVCrAl)N with different architectures onto the surface of Ti-6Al-4V alloy with the initial coarse-grained and ultrafine-grained structure using arc physical vapor deposition. We designed and prepared three coating architectures: a monolayer nitride coating (TiZrVCrAl)N, a multilayer coating consisting of nine alternating layers of TiZrVCrAl and (TiZrVCrAl)N, and a multilayer coating consisting of 720 alternating layers of (TiZrVCrAl)N and TiN, with a total thickness not exceeding 2 microns. We evaluated their protective performances by nanoindentation and scratch tests. Importantly, the effect of the substrate microstructure on the coatings’ performance is investigated by comparing their mechanical behavior on coarse-grained and ultrafine-grained Ti-6Al-4V. Our experimental results show that the coating performance improves with increasing number of layers in the coating, and this effect is even more pronounced for the multilayer coating deposited on the ultrafine-grained titanium alloy substrate. We also find that the (TiZrVCrAl)N/TiN (720 layers) multilayer coating deposited on the UFG Ti-6Al-4V alloy substrate exhibits the highest H/E- and H³/E²-values, indicating the coating’s high innovative potential for performance in extreme conditions. The origins of this phenomenon are analyzed and discussed. Full article

Laser powder bed fusion has attracted increasing attention for the production of metallic substrates intended for surface functionalization by advanced physical vapor deposition coatings. This study investigates the influence of the substrate manufacturing route on the performance of titanium–aluminum–silicon nitride-coated AISI 316L stainless steel, with particular emphasis on substrates produced by laser powder bed fusion. Conventionally manufactured and additively manufactured AISI 316L substrates were coated with a titanium–aluminum–silicon nitride layer using high-power impulse magnetron sputtering. The substrates were characterized by tensile testing and microhardness measurements, while coating thickness and uniformity were evaluated using the crater ball method. The mechanical integrity of the coating–substrate system was assessed by progressive load scratch testing. The additively manufactured substrate exhibited a significantly higher yield strength (411 MPa) compared to the conventionally manufactured material (257 MPa), together with increased microhardness. The titanium–aluminum–silicon nitride coating showed a uniform thickness of 4.47 µm and a well-defined coating–substrate interface. Scratch tests revealed a delayed onset of coating damage on additively manufactured substrates, with the transition to severe adhesive failure occurring at higher normal loads compared to the conventionally manufactured substrate. These results demonstrate that AISI 316L stainless steel produced by laser powder bed fusion provides a mechanically robust substrate for titanium–aluminum–silicon nitride coatings deposited by high-power impulse magnetron sputtering, with favorable coating response under progressive loading conditions. Full article

This work focuses on obtaining a titanium nitride coating on the surfaces of titanium and its alloy powders using a novel method, self-shearing reactive milling, under a nitrogen pressure of 50 bar. The Ti, Ti6Al4V, and Ti-5553 spherical powders were milled for up to 10 h at ambient temperature without grinding balls. As a result of the experiments, a thin, brittle TiN coating formed on the powders’ surfaces. The cross-sections of the milled powders reveal that the TiN layer thickness is in the nanometer range (about 500 nm). By analyzing the sequence of X-ray diffraction patterns, it is evident that only for the Ti6Al4V powder milled for 10 h, two peaks are observed that can be attributed to a TiN phase. On the other hand, Raman spectroscopy revealed characteristic TiN spectra even for samples collected at the initial stage of self-shearing reactive milling. An important aspect of the experiment was the preservation of the spherical shape of the milled powders, which makes them a potential feedstock for additive manufacturing of functionally graded biomaterials. Full article

Background: Tantalum in cytotoxicity tests showed no toxicity effect, as well as promoting bone regeneration through the differentiation, proliferation, mineralisation and adhesion of osteoblasts in in vitro and in vivo studies. This study aims to determine and compare the chemical composition, roughness and wettability of non-coated commercially pure titanium (CpTi) disc surfaces with CpTi discs that have been coated with tantalum oxynitride film (TaON) via a modified plasma sputtering coating technique. Methods: Two groups were tested that included the TaON-coated CpTi discs and non-coated CpTi discs. A modified reactive plasma sputtering apparatus was used for coating the CpTi discs with TaON at different time durations, i.e., 4, 6, and 8 h. The surface properties of the coated and non-coated discs were studied using X-ray diffraction (XRD) analysis, energy dispersive spectroscopy (EDS), scanning electron microscopy (SEM), and contact angle measurement. Results and Conclusions: The results showed that 8 h was the best coating duration. The XRD analysis showed the presence of a new peak in the case of the TaON-coated CpTi disc that was absent in the non-coated CpTi disc. Furthermore, the SEM analysis revealed that the TaON-coated CpTi disc showed a better distribution of surface roughness compared to the non-coated disc. The non-coated CpTi discs showed lower wettability compared to the TaON-coated CpTi discs. The result shows the importance of a TaON coat in changing the surface properties of CpTi which will be used in dental implants; this result will enhance the idea of surface treatment and its relationship with the enhancement and acceleration of bone formation around dental implants in future. The novelty of the newly modified reactive plasma sputtering technique used in this study as a coating technique for CpTi discs lies in the promising tantalum oxynitride, as Ta had no toxicity effect in cytotoxicity tests and promoted adhesion, proliferation, differentiation, the mineralisation of osteoblasts and bone regeneration in vitro and in vivo. The mean target of the work is to enhance the osseointegration of CPTi dental implants with different surface coatings including Ta oxide, nitride and oxynitride. The results of the first two coatings are already published, and the third coating technique is investigated in this study. Full article

Titanium carbonitride (TiCN) has emerged as a significant material, bridging the gap between traditional binary carbides and nitrides to offer a comprehensive combination of superior mechanical strength, exceptional wear resistance, and excellent chemical stability. This review comprehensively surveys the research progress in TiCN materials, tracing their evolution from coating technologies to the forefront of nanoparticle synthesis and application. We begin by examining conventional physical vapor deposition (PVD) and chemical vapor deposition (CVD) techniques for producing TiCN coatings, highlighting their roles in extending the service life of cutting tools, forming tools, and components subjected to abrasive and corrosive environments. The discussion then shifts to the synthesis of TiCN nanoparticles, covering advanced methods such as laser ablation, solvothermal processes, and precursor pyrolysis, with a critical analysis of their advantages and limitations in controlling particle size, morphology, and stoichiometry. The enhancement in the nanoscale formulation of TiCN on mechanical properties including hardness, fracture toughness, and load-bearing capacity is through grain refinement and nanocomposite strengthening mechanisms. Furthermore, the review delves into the corrosion protection mechanisms imparted by TiCN, whether as a dense coating/film or as a reinforcing nanophase in composite matrices. Finally, we identify current challenges in scalable synthesis and phase stability, and propose future directions, such as the development of multi-functional TiCN-based nanocomposites and hybrid coating architectures for next-generation applications in extreme environments. This work aims to provide a structured reference that connects fundamental material properties with applied technological advancements across the micro- to nanoscale. Full article

The global polymer waste burden has catalyzed a shift from linear “production–use–disposal” systems to circular models that prioritize recycling, reuse, and value retention. This article proposes an integrated, technology-ready roadmap for mechanical recycling and reuse of commodity and bio-based polymers via filament re-extrusion and Additive Manufacturing (AM). Building upon recent findings on performance envelopes of virgin vs. recycled Polylactic Acid (PLA) filaments processed by Fused Deposition Modeling (FDM), process parameter sensitivities (layer height, infill density) and their statistical optimization, and functional reinforcement routes (aluminum: Al, alumina: Al₂O₃, titanium: Ti, and Nano Boron Nitride: nano-BN), we articulate (1) a process–structure–property (PSP) mapping; (2) a low-defect, low-energy filament re-extrusion protocol; and (3) a graded-value strategy for upcycling mixed polymer streams. Across case analyses, we show that recycled PLA can achieve near-parity with virgin PLA when extrusion quality and printing parameters are controlled, and that ceramic/metal nanofillers enable thermal management and biocompatibility benefits crucial for durable reuse scenarios. Full article