Search Results (3,815)

The integration of advanced semiconductor architectures strictly mandates process thermal budgets below 200 °C, positioning low-temperature PECVD of silicon nitride (SiN_x) film as a critical layer. However, SiN_x film deposited at sub-200 °C inherently exhibits sluggish deposition kinetics and degraded spatial uniformity. To overcome these bottlenecks, this study systematically investigates the regulatory mechanisms of the NH₃ precursor within SiH₄/N₂-based plasmas under varying chamber pressures and substrate temperatures. The results show that the introduction of NH₃ at 2.1 Torr, leveraging its facile plasma dissociation, drastically enhances the deposition rate from 18.2 to 39.1 Å/s and improves thickness uniformity by 1.07%. Meanwhile, NH₃ supplies abundant highly reactive radicals that elevate the refractive index and reinforce compressive stress. Furthermore, film properties exhibit a higher sensitivity to pressure than to temperature, primarily due to the pronounced influence of pressure on plasma dynamics and collision frequencies, whereas the effect of temperature remains comparatively minor. This phenomenon is clearly demonstrated by the Si–H and N–H content. This study validates that operating at low chamber pressures maximizes the collision-free travel distance of SiN_x radicals, providing an optimized and quantified process window for high-volume manufacturing of low-temperature SiN_x film. Full article

The Casas Novas gold deposit is located in the Escoural Gold District of the Ossa Morena Zone (OMZ, SW Iberia) and consists of an orogenic gold system characterized by structurally controlled mesothermal lodes, which are related to a major shear zone. The mineralization shows evidence of two distinct metallogenic phases during regional metamorphism: (i) an early higher-temperature stage marked by Co-Ni-rich loellingite hosting Au-(Ag) alloys accompanied by pyrrhotite, and (ii) a later low-temperature stage with arsenopyrite, gold, maldonite and Bi-Te sulfosalts. Detailed textural analysis documents the evolution from initial Au-Ag alloys enclosed in Co-Ni-rich loellingite to subsequent Au-Bi-Te phases and newly formed arsenopyrite. The results show the thermal and chemical changes in the system, demonstrating the importance of fluid–rock interactions in the redox conditions, which became more oxidized, controlling the gold deposition. The comprehensive overview of the processes that led to the concentration of gold in the Casas Novas deposit provides a valuable contribution to the ongoing studies into the auriferous region of the Escoural Gold District. Full article

Comprehensive mineralogical and technological investigations of tin-bearing weathering crusts from the Syrymbet deposit (Northern Kazakhstan), characterized by low tin grades and a high degree of mineral dispersion, are presented. The particle-size distribution, mineralogical composition, chemical composition, and the distribution of tin among size fractions and processing products were studied. The results show that the majority of tin is associated with the fine-grained clay fraction, which contains up to 70%–74% of the total metal inventory. Conventional hydrocycloning and gravity concentration methods were found to be ineffective due to the fine dissemination and encapsulation of tin mineralization, with more than 99% of the tin reporting to gravity separation tailings. In the untreated material, tin mineralization is predominantly represented by cassiterite, as confirmed by electron microscopy and energy-dispersive X-ray microanalysis. Thermal activation at 450 °C under oxygen-free conditions was shown to induce profound transformation of the original cassiterite mineralization. Cassiterite was not detected in the thermally activated products; instead, newly formed multiphase aggregates containing tin, bismuth, iron, silicon, aluminum, carbon, and oxygen were identified. These aggregates exhibit characteristic film-globular morphologies ranging in size from 1–3 to 100–200 μm. As a result of thermal treatment, tin concentrations in the thermal products increased to 1500–1864 g/t, corresponding to ore-grade levels. The obtained results demonstrate the potential of thermal activation as an effective approach for the utilization of previously low-grade tin-bearing weathering crusts and for expanding the tin mineral resource base of Kazakhstan. Full article

Graphite-filled polymer composites exhibit high in-plane thermal conductivity but suffer from severe thermal anisotropy, which limits their practical heat dissipation performance in the thickness direction. In this study, hierarchically structured Al/GO@AgNPs hybrid fillers were developed to enhance the through-plane thermal conductivity of polypropylene (PP)/graphite composites. The hybrid fillers were fabricated through GO-assisted surface modification of Al particles followed by electroless deposition of Ag nanoparticles. The GO layer improved the interfacial characteristics of Al and served as a platform for Ag nucleation, resulting in the formation of Ag nanoparticles on the Al/GO surface. When incorporated at a low loading of 1.0 wt%, the Al/GO@AgNPs hybrid filler increased the through-plane thermal conductivity from 11.24 to 48.33 W·m⁻¹·K⁻¹, corresponding to more than a fourfold enhancement compared with the graphite-only composite, while maintaining an in-plane thermal conductivity of 106.87 W·m⁻¹·K⁻¹. This improvement is attributed to the bridging effect of spherical hybrid fillers between adjacent graphite platelets and the resulting reduction in interfacial thermal resistance in the through-plane direction. The proposed hybrid filler system effectively mitigates thermal anisotropy and provides a promising strategy for designing highly filled polymer composites for advanced thermal management applications. Full article

As MicroLED technology scales below 10 μm, Cu is increasingly utilized for interconnects due to its high thermal and electrical conductivity. However, Cu-induced degradation in GaN remains a critical reliability concern. This study investigates 10 nm Ni, Ti, and Pt barriers in Cu/Al stacks on green GaN-on-Si devices with a mesa diameter of 350 μm after isothermal annealing at 100 °C, 200 °C, and 300 °C for 2 h, aiming to provide a reference for future barrier design in scaled MicroLED devices. Electrical and electroluminescence measurements show that while 100–200 °C annealing optimizes contact resistance, higher temperatures cause Cu interdiffusion with metal-dependent severity. Ti emerges as the optimal general-purpose barrier, achieving the highest EL intensity among annealed samples at 300 °C, demonstrating that higher-temperature annealing enhances rather than degrades performance, thanks to effective Cu blocking and improved contact formation. Pt offers comparable barrier effectiveness with superior thermal stability, maintaining stable electrical characteristics and retaining 42% of peak EL intensity even at 300 °C. In contrast, Ni exhibits insufficient blocking, suffering 83% EL quenching and severe electrical degradation at 300 °C. Notably, as-deposited PtCuAl devices show an unexpected carrier localization effect yielding the highest recorded EL intensity (2750 a.u.), suggesting contact engineering opportunities. These findings establish a barrier effectiveness hierarchy (Ti ≈ Pt >> Ni) for thermal stability. Full article

The Songpan-Ganzi and Eastern Kunlun region on the northern margin of the Tibetan Plateau is a key area for the evolution of the Paleo-Tethys tectonic domain and hosts abundant gold, lithium, and polymetallic mineral resources. To reveal the deep structure of this region and its metallogenic background, this study constructed a lithospheric electrical structure model based on magnetotelluric (MT) data along a profile traversing tectonic units such as the Qiangtang, Songpan-Ganzi, and Eastern Kunlun blocks. Data processing, dimensionality analysis, and two-dimensional inversion were performed. The results show that a large-scale, funnel-shaped conductor, originating from the upper mantle and penetrating the middle-lower crust, exists beneath the Songpan-Ganzi and Qiangtang terranes, indicating a major channel for deep-seated thermal material upwelling. Driven by Cenozoic tectonic reactivation, the thermal materials ascended along pre-existing lithospheric weak zones formed during the closure of the Paleo-Tethys Ocean. It spread extensively within the upper-middle crust of the Songpan-Ganzi terrane and migrated to the Eastern Kunlun orogenic belt via complex fault systems, ultimately forming low-resistivity bodies that closely coincide with the locations of major shallow ore-controlling faults. This electrical model suggests the presence of a “thermal material channel” system extending from the mantle to the shallow crust. The study suggests that the migration pathways of ore-forming fluids, represented by gold deposits in the Eastern Kunlun metallogenic belt, are highly correlated with the fault-magma channel system constituted by intra-crustal conductors. In contrast, the lithium-rich granitic magmatism associated with lithium mineralization within the Songpan-Ganzi terrane may be related to the deep thermal background reflected by the large-scale conductor in the upper mantle. From the perspective of electrical structure, this study suggests that mineralization in this region may be closely linked to deep crust–mantle processes. The reactivation of pre-existing tectonic-magmatic channels by Cenozoic thermal material is key to controlling the distribution pattern of dominant shallow mineral resources. The research results provide important geophysical constraints for a deeper understanding of the tectonic–magmatic–mineralization coupling mechanism on the northern margin of the Tibetan Plateau. Full article

This study investigates the influence of barrel filling ratio on the microstructure, phase composition, and tribological performance of detonation-sprayed Cr₃C₂–NiCr coatings. Coatings were deposited at barrel filling ratios of 43% and 53% under identical spraying conditions. Microstructural characterization revealed the formation of dense lamellar coatings with low porosity and uniform distribution of Cr₃C₂ carbide particles within the NiCr metallic matrix. Compared with the coating deposited at a barrel filling ratio of 43%, the coating deposited at 53% exhibited a denser microstructure. X-ray diffraction analysis confirmed that Cr₃C₂ and NiCr remained the dominant phases after spraying, while a minor amount of Cr₇C₃ formed due to partial decarburization of chromium carbide during thermal exposure. Tribological performance was evaluated under dry sliding conditions using a ball-on-disc configuration at normal loads of 10 and 15 N and sliding speeds of 5 and 10 cm/s. Wear volume was determined from the geometry of the wear track after testing, and wear rate was calculated accordingly. The coating produced at a barrel filling ratio of 53% demonstrated improved wear resistance under elevated loads despite exhibiting a higher coefficient of friction. The minimum wear rate reached 1.23 × 10⁻⁴ mm³/(m·N), which was associated with reduced porosity and enhanced structural integrity of the coating. The obtained results demonstrate that optimization of detonation spraying parameters significantly affects coating structure and tribological behavior. The developed Cr₃C₂–NiCr coatings are promising protective materials for components operating under severe friction and wear conditions, including industrial and high-temperature engineering applications. Full article

This work investigates the potential of additive manufacturing (AM) technologies for prototyping and developing functional components in thermal systems, with particular emphasis on thermal and mechanical performance. The study focuses on two complementary prototyping strategies: (i) the use of metal-filled polymer filaments in Fused Deposition Modeling (FDM), also known as Material Extrusion (MEX) according to ISO/ASTM 52900:2022, and (ii) a hybrid approach combining polymer 3D printing with conductive coating and electrochemical copper deposition. While metal-filled filaments provide a rapid and low-cost solution for early-stage prototyping, their mechanical properties remain similar to those of the polymer matrix, limiting their applicability in load-bearing structures. In contrast, the hybrid method enables the fabrication of hollow metallic geometries with improved thermal and electrical conductivity. This approach is more time-consuming and process-intensive and is therefore considered a subsequent stage in the prototyping workflow following initial MEX-based design iterations. Compared with conventional polymer-based MEX, several AM approaches enable the development and fabrication of fully metallic or metal-functional structures, including Powder Bed Fusion (PBF), Directed Energy Deposition (DED), and hybrid polymer–metal methods based on electroplating. Furthermore, understanding mechanical properties such as tensile strength is essential for assessing the applicability of AM materials in energy system components. The results contribute to bridging the gap between rapid prototyping and the implementation of advanced AM technologies in thermal-related applications. Full article

Iron-based Fischer–Tropsch synthesis (Fe-FTS) catalysts are central to coal-to-liquid (CTL) processes but suffer from rapid and complex deactivation under industrial conditions. This review critically examines the key deactivation mechanisms, including carbon/wax deposition, hydrothermal sintering, chemical poisoning (S, Cl, As), and mechanical attrition, and evaluates modern regeneration strategies. These strategies include supercritical fluid extraction for wax removal, controlled oxidative decoking, reductive reconstruction of active iron carbides (χ-Fe₅C₂), chemical de-poisoning, and structural upcycling. We also discuss emerging techniques such as non-thermal plasma and supercritical fluid-assisted reactivation. Finally, we highlight challenges in irreversible phase transformation, in -situ regeneration engineering, and economic feasibility, and outline future directions toward regeneration-friendly catalyst design and advanced syngas purification for a circular CTL economy. Full article

Additive manufacturing (AM) has emerged as a transformative manufacturing technology for producing complex components with unprecedented design flexibility. However, the widespread application of AM parts in tribological environments is often limited by inherent defects such as high surface roughness, porosity, residual stresses, anisotropy, and weak interlayer bonding, which adversely affect friction, wear resistance, and tribocorrosion performance. This review critically examines the tribological behavior of AM materials and components, emphasizing the influence of processing routes, material selection, secondary reinforcing phases, and microstructural evolution on tribological performance. Particular attention is given to surface engineering strategies, including thermal spray coatings, laser surface treatments, plasma electrolytic oxidation, vapor deposition technologies, and mechanical surface modification techniques for mitigating AM-induced defects and improving surface durability. Recent advances in machine learning (ML) and artificial intelligence (AI) for wear prediction, process optimization, and intelligent tribological monitoring are also discussed. The review highlights the relationships among manufacturing parameters, surface integrity, and wear mechanisms, while identifying key challenges associated with process variability, long-term reliability, and industrial implementation. Future research should focus on multifunctional surface systems, smart coatings, real-time condition monitoring, and data-driven design approaches to accelerate the deployment of tribologically optimized AM components in aerospace, biomedical, automotive, and energy applications. Full article

The technological performance of bentonite in foundry applications is strongly influenced by the nature of its exchangeable interlayer cations, with sodium bentonites generally exhibiting superior swelling, plasticity, and bonding properties compared with calcium bentonites. Given the limited availability of natural sodium bentonite, upgrading abundant calcium-rich bentonite resources holds significant industrial interest. In this study, a natural Ca-rich bentonite from the Bijelo Polje deposit (Bar, Montenegro) was upgraded by alkali activation using Na₂CO₃ and evaluated as a binder for green sand foundry molds. The raw bentonite was characterized by physicochemical, mineralogical, and structural analyses, confirming its Ca-type character and suitability for sodium activation. Activation was performed using 2–6 wt.% Na₂CO₃, with the optimum treatment achieved at 5 wt.% Na₂CO₃. The activated bentonite was subsequently characterized using structural, textural, thermal, and physicochemical methods. Alkali activation significantly improved the key technological properties of the material, increasing the free swelling capacity from 7 to 20 cm³, the specific surface area from 27.4 to 45.8 m² g⁻¹, the cation exchange capacity from 74.6 to 89.5 meq/100 g, and the plasticity index from 79.6% to 193.4%. XRD, ATR–FTIR, and thermal analyses confirmed successful sodium activation while preserving the fundamental montmorillonite structure. Evaluation of foundry-relevant properties, including refractoriness, methylene blue adsorption, gas permeability, thermal stability, and bonding strength, demonstrated that the activated bentonite satisfies the technological requirements for green sand molding of both ferrous and non-ferrous alloys. These findings demonstrate that Na₂CO₃ activation is an effective and resource-efficient approach for converting natural Ca-rich bentonite into a high-performance foundry binder. Full article

High-temperature corrosion severely impairs the service life of boiler heating tubes and threatens the safe and economical operation of thermal power units. With diversified fuels (coal, biomass and refuse-derived fuels) and continuously elevated operating parameters (steam temperature exceeding 620 °C for ultra-supercritical units), boiler heating surfaces are exposed to increasingly complex corrosive environments. High-temperature oxidation, sulfidation, chlorination, molten salt hot corrosion and deposit-induced multi-factor coupled corrosion coexist and exacerbate each other. This paper adopts a four-dimensional analytical framework of “mechanisms–technologies–materials–evaluation” to systematically summarize relevant research progress. From the perspective of corrosion mechanisms, the evolution of understandings from single high-temperature oxidation to multi-factor coupled corrosion is reviewed. In terms of surface coating technologies, seven mainstream processes including HVOF/HVAF spraying, plasma spraying, cold spraying, laser cladding and weld overlay are compared in terms of preparation characteristics and engineering applicability. For coating materials, twelve material systems such as NiCr alloys, MCrAlY, cermets, Fe-based amorphous/nanocrystalline alloys and high-entropy alloys are evaluated for their corrosion resistance under diverse service conditions. As for monitoring and evaluation, this work introduces full-range corrosion management technologies covering electrochemical monitoring, non-destructive testing, numerical simulation and life assessment. Finally, the paper discusses the application prospects of gradient coating design, AI-assisted material screening and digital twin technology, and points out key research gaps including long-term service reliability verification of coatings and quantitative prediction models for multi-factor coupled corrosion. Full article

Iron powder cores are widely used in cost-sensitive low- to medium-frequency applications because of their high saturation magnetisation, low cost and favourable formability. However, the low electrical resistivity of iron powders favours continuous conductive pathways between adjacent particles, leading to high-frequency eddy-current loss and heat accumulation. To combine electrical insulation, interfacial stability, magnetic-property retention and thermal diffusion in a single coating, a synergistic insulation/thermal-conduction coating based on thiol-functionalised boron nitride was designed for iron-based magnetic powder cores. Hexagonal boron nitride was surface-modified through ultrasonic activation followed by grafting with a mercaptosilane coupling agent, forming covalent linkages on the boron nitride surface. The resulting functionalised nanosheets were deposited onto water-atomised iron powders through interfacial interactions between nitrogen- and sulfur-containing functional groups and the iron surface. A coating content of 5 wt.% produced a relatively continuous and uniform interfacial layer with limited agglomeration, enabling the magnetic powder cores to combine interparticle insulation, loss reduction, magnetic-property retention and thermal transport. The optimised core exhibited a volume resistivity of 58.7 Ω·m and a total core loss of 81.2 kW/m³ at 10 mT and 100 kHz, corresponding to a 20.8% reduction relative to the pure iron core. The sample retained a saturation magnetisation of 201.4 emu/g and an effective permeability of 67.5 at 100 kHz, while achieving a thermal conductivity of 55.2 W/(m·K) and a thermal impedance of 0.215 K·m²/W. Loss-separation analysis indicates that the continuous insulating layer restricts interparticle induced-current pathways and suppresses high-frequency eddy-current loss, while the two-dimensional boron nitride framework promotes internal thermal diffusion. Full article

MXenes, a rapidly expanding family of two-dimensional transition-metal carbides and nitrides, are increasingly viewed as strong candidates for defense-oriented multifunctional systems because they combine metallic conductivity, surface tunability, mechanical flexibility, and solution processability within a lightweight platform. Unlike conventional metals, ceramics, and semiconductors, which usually optimize one or two parameters at the expense of density, brittleness, or integration compatibility, MXenes offer a rare opportunity to coordinate electromagnetic, mechanical, thermal, and sensing functions within one material family. Different from existing reviews that focus on laboratory-level record performance or single-function optimization, this review presents an innovative deployment-oriented perspective and fills the research gap of systematic military-oriented evaluation for MXenes. In this review, we examine MXenes from a deployment-oriented perspective rather than through isolated record values. We first summarize their formation chemistry and major synthesis routes, including HF and in-situ HF etching, bifluoride and alkaline methods, molten-salt strategies, electrochemical approaches, and precursor-free chemical vapor deposition. We then discuss the principal levers of property regulation, focusing on composition design, surface-termination control, and heterostructure engineering, and show how these strategies shape the performance envelopes relevant to shielding, stealth, impact response, energy storage, and sensing. This review constructs a full-chain analytical framework from synthesis, property regulation to military application and deployment challenges for the first time. Finally, we identify the main barriers to translation, especially manufacturing inconsistency, termination heterogeneity, oxidation and interfacial degradation, and limited application-level validation, and outline the most realistic paths toward deployable defense technologies. Full article

To address the increasing demand for energy-efficient buildings, this study experimentally characterizes the effective (λ_eff) and apparent (λ_app) thermal conductivity of 3D-printed polymer plates. While 3D printing offers significant design flexibility, a lack of comprehensive comparative data between printable polymers and conventional building materials limits their integration into large-scale facade systems. This research investigates four distinct materials: standard polylactic acid (PLA Basic), foamable poly-L-lactic acid (PLA Aero), amorphous polyethylene terephthalate glycol (PETG), and carbon fiber-reinforced polyethylene terephthalate (PET-CF). Utilizing the guarded hot plate (GHP) method (ASTM C177, EN 12667, EN 12939), steady-state heat flux and temperature gradients were measured. The methodology incorporates a rigorous uncertainty analysis (k = 2) addressing the inherent inhomogeneity of additively manufactured components. Results demonstrate significant variations: PLA Aero achieved a 57.3% reduction in thermal conductivity (0.114 ± 0.005 W/(m·K)) compared to PLA Basic (0.267 ± 0.011 W/(m·K)), while PET-CF showed increased conductivity (0.533 ± 0.021 W/(m·K)) due to carbon fiber bridging. Notably, multi-layered PLA Aero assemblies outperformed conventional double-glazed units, reaching a minimum λ_app of 0.051 W/(m·K). These findings validate the GHP method for 3D-printed polymers and provide a technical foundation for material selection in next-generation, energy-efficient smart facades. Full article