Search Results (182)

This work is devoted to the study of the influence of mechanical activation of aluminum, as well as its modification with graphite on the combustion processes of solid rocket propellant (SRP). Experiments were conducted to determine the ignition induction period, combustion rate and combustion products. Experimental work on ignition and combustion diagnostics was carried out using a diagnostic system at the Institute of Space Propulsion (ISP) of Nanjing University of Science and Technology. A multifunctional combustion diagnostic system was used to characterize the combustion processes of finished SRP samples. A high-speed camera was used to capture the combustion surface regression for various fuels, which can be used to derive their burning rate. The addition of graphite during the mechanochemical activation (MCA) of aluminum significantly affected particle shape and the state of the oxide film, improving the batch homogeneity and increasing the specific surface area. The optimal graphite concentration was approximately 10%, providing additional activation, while 20% graphite caused recoating of the particles and reduced processing efficiency. At constant pressure, it was found that MCA and the introduction of graphite accelerated composite combustion without disrupting stable combustion, with a relatively uniform front. The highest combustion velocity (3.0 mm s⁻¹) was achieved with 10% graphite due to effective heat transfer and catalysis, while increasing its content to 20% reduced the combustion velocity, indicating an optimum of approximately 10%. Full article

Recycled polymer-rich residues can alter several functions of wood-based panels, but claims of multifunctionality require property-specific evidence and transparent treatment of replication. Three-layer spruce particleboards were therefore prepared with 10 wt.% painted or unpainted polypropylene bumper granules, high-density polyethylene fuel-tank granules, tire rubber, seal-and-carpet residues, or electrical-cable fractions in the core layer. Two hybrid formulations contained 10 wt.% recycled rubber-rich filler plus 10 wt.% expandable graphite. Transient plane source measurements were evaluated at the specimen-pair level (two pairs per formulation); normal-incidence sound absorption and radiant-heat mass loss were complementary descriptive screens because the archived datasets contained one spectrum or one exposed specimen per formulation. Mean thermal conductivity varied only from 0.1908 to 0.2075 W m⁻¹ K⁻¹ (−5.3% to +3.0% relative to the reference). The graphite hybrids showed the clearest change in transient response: thermal diffusivity increased by 19.6–20.1%, whereas volumetric heat capacity decreased by 14.5–16.7% and thermal effusivity by 6.5–8.7%. SC10G10 had the highest mean absorption coefficient over 126–6400 Hz (0.210; +46.2%) and the lowest mass loss after 600 s at 30 kW m⁻² (37.48%; −17.72%). Macroscopic and polarizing optical images showed formulation-dependent filler distribution and visible interfacial spaces, but they did not establish bonding mechanisms or quantify porosity. The results identify promising formulation-dependent responses while also defining the replication and structural measurements needed before application-level claims can be made. Full article

The valorization of agricultural waste into high-value carbon nanomaterials offers dual benefits: it reduces pollution and provides low-cost materials for sustainable technologies. This work synthesizes graphene-like carbon from Ghars date waste via mild KOH-assisted pyrolysis at 1000 °C. The material (G-GhW1000) exhibits a sharp (002) XRD peak at 26.16° (d-spacing = 3.40 Å), a characteristic π → π* transition at 253 nm, and a high C/O ratio of 27.37. Dispersed in tap water (0.5 g/L) by simple hand shaking (without ultrasonication), it serves as a photothermal nanofluid in a modified single-slope solar still (MSS). Under outdoor conditions, the MSS produces 4.69 L·m⁻²·day⁻¹, which is 18.7% higher than a conventional still, with thermal efficiency rising from 27.2% to 30.8% (with a reproducible 19.0% enhancement in summer). Samples prepared at 800 °C and 900 °C give 4.0% and 6.4% lower yields, while the 1100 °C sample gives only 6.0% improvement, confirming 1000 °C as the optimal temperature. The superior performance at 1000 °C is attributed to the optimal balance between graphitization, deoxygenation, and structural integrity, as evidenced by XRD, FTIR, EDX and UV-Vis analyses. The enhanced performance is linked to higher water temperature (68 °C) and larger ΔT. The distilled water meets WHO standards (TDS 9.35 mg/L, >99.4% reduction) with no detectable graphene-like carbon carryover. This work demonstrates the potential of waste-derived graphene-like carbon as a low-cost additive for solar desalination, addressing water scarcity and waste management within a circular economy framework. To our knowledge, this is the first study to use Ghars date waste-derived graphene-like carbon in a solar still. Full article

Electrified steam methane reforming (eSMR) is emerging as a promising technology for the decarbonization of the chemical industry and low-carbon hydrogen production by coupling renewable electricity with renewable gaseous feedstocks such as biomethane. In this work, structured Ni-based catalysts washcoated on highly thermally conductive SiC open-cell foams (OCFs) were developed and evaluated for biomethane steam-reforming operating conditions. Two catalyst formulations, 30 wt.% Al₂O₃_30 wt.% CeO₂_20 wt.%Ni and SiC_30 wt.% Al₂O₃_30 wt.%Ce_0.25Zr0.75 O₂_20 wt.%Ni, were tested in a laboratory-scale indirectly electrically heated reformer. The high thermal conductivity of the SiC-structured support ensured efficient heat transfer throughout the reactor, limiting radial temperature gradients to below 10 °C. Both catalyst formulations exhibited excellent catalytic performance; however, the Ce_0.25Zr0.75O₂-promoted catalyst achieved the best results, maintaining equilibrium methane conversion at a gas hourly space velocity above 7000 h⁻¹ while reaching a specific electrical energy consumption of 2.06 kWh/Nm³ of produced H₂ projected for industrial-scale efficiency. Notably, these performances were obtained with a catalyst loading approximately 20–50% lower than that of conventional commercial alumina pellet catalysts. XRD characterization did not reveal the formation of crystalline graphitic carbon after catalytic operation. Furthermore, the structural evolution of the Ce–Zr–O highlights the active role of the mixed oxide in promoting redox processes and maintaining catalytic activity under reaction conditions. Overall, these results demonstrate that the combination of highly conductive SiC-structured supports and Ce–Zr-promoted Ni catalysts significantly enhances both the thermal and catalytic efficiency of eSMR. The proposed catalyst provides a promising route toward compact, energy-efficient, and decentralized hydrogen production from biomethane, supporting the electrification and decarbonization of future hydrogen generation technologies. Full article

In the present paper, a scalable and continuous process with maximum treatment temperatures of 2000 °C for making cellulose-based carbon fibers (CFs) having Young’s moduli of up to 230 $\mathrm{G}$$\mathrm{Pa}$ is presented. This unexpected high modulus was realized by using a boric acid (BA)-doped viscose precursor yarn. Such a precursor shows significantly improved orientability during carbonization, resulting in highly oriented CFs. For clarifying the underlying effect, a BA-doped and an undoped precursor (reference) were carbonized at different stretch levels, and the resulting CFs were systematically analyzed in terms of structural parameters characterizing the crystalline phase, i.e., crystallite dimensions ($L_a$, $L_c$), lattice plane spacing ($d_{002}$), and crystallite orientation ($⟨{cos}^2\varphi ⟩$). Moreover, electrical resistivity and mechanical properties were determined. It was found that BA promotes the formation of graphite-like structures and their alignment with the fiber axis. Finally, both effects result in significantly improved CF properties, particularly electrical conductivity and Young’s modulus, which are nearly three times and two times higher, respectively, than those of the reference. To explain the effectiveness of BA during thermal conversion, a microstructural mechanism is proposed based on results from a uniform stress model. Full article

The magmatic Ni-Co-Cu mineralization in the Iken deposit in the central part of the Kun-Manie complex, Amur Oblast, Russia, hosted by an olivine-bearing websterite, is of a low-sulfide type. The fine-grained disseminations of base metal sulfides (BMS), dominantly pyrrhotite, pentlandite (a major source of Ni of industrial importance), and chalcopyrite, are followed by a scarce Pd-Pt-Ag mineralization. Elevated contents of Al in orthopyroxene (mean 2.78 wt.% Al₂O₃) along with Al–Na enrichment in clinopyroxene (diopside; mean 5.10 wt.% Al₂O₃) are associated with highly aluminous compositions of low-chromium members of the spinel–hercynite series. High levels of TiO₂ in kaersutite and titanian phlogopite also reflect a pronounced degree of fractionation of the ore-forming melt. Minor portions of sulfide melt are distributed evenly as a result of immiscibility at advanced stages of orthopyroxene crystallization, after the formation of olivine. Differentiated grains of droplet-like BMS largely settled in situ close to grain boundaries of orthopyroxene or occupied interstitial spaces of pyroxenes and olivine in association with spinel–hercynite and fluorapatite. A combination of late saturation in S with relatively quick cooling rates of the hypabyssal body prevented the effective settlement and accumulation of sulfide droplets in the ore zone. The well-developed lamellae of troilite (Fe₅₀S₅₀) exsolved from the host pyrrhotite Fe₄₈S₅₂ during subsolidus cooling, as a consequence of a low-temperature reaction triggered by a sudden drop in fO₂. An influx of mantle-derived fluid bearing CO₂, CO, and CH₄ with the rising magma could be the primary cause of the fO₂ reduction. Also, graphite-bearing metasedimentary rocks could have been assimilated. Tiny grains of minerals of noble metals (moncheite and merenskyite with essential amounts of melonite component, sperrylite, hessite, alloy Au_63.2Ag_36.8, and argentopentlandite) deposited late in a fluid-enriched medium under submagmatic conditions. Full article

Biomass-derived carbons are promising sustainable anode materials for lithium-ion batteries (LIBs) and sodium-ion batteries (SIBs) because biomass is renewable, abundant, low-cost, and naturally diverse in composition and morphology. Lignocellulosic frameworks, intrinsic heteroatoms, and biomass-derived inorganic species can be converted through carbonization, activation, graphitization, and doping into carbon architectures with tunable porosity, carbon ordering, and surface chemistry. This review first summarizes the compositional and structural features of biomass precursors and explains how processing conditions convert them into carbon frameworks. Recent advances in biomass-derived carbon anodes are then discussed by comparing the distinct design requirements for LIBs and SIBs. For LIBs, accessible surface area, hierarchical porosity, heteroatom-derived active sites, and improved electronic conductivity are generally beneficial for enhancing Li⁺ storage and rate capability. In contrast, SIB hard carbons require controlled surface exposure, expanded turbostratic spacing, and closed or latent pores to improve Na⁺ storage reversibility and initial Coulombic efficiency. These comparisons emphasize that biomass-derived carbon anodes should be designed according to system-specific storage mechanisms rather than a universal carbon design strategy. Full article

Saltwater batteries can be made using brine from the desalination of seawater for low-cost energy storage. This study investigates the performance characteristics of saltwater batteries for potential off-grid energy applications. The systematic investigation of 15 electrode pairings from six electrodes (copper, iron, zinc, graphite, aluminium, and tin) across eleven concentration levels, combined with studies on electrode geometry, spacing, and volume, provides comprehensive insights into galvanic cell behaviour for saltwater batteries. Results indicate that the open-circuit voltage (OCV) is primarily determined by electrode potential differences rather than salt concentration, with zinc-carbon and aluminium-carbon pairings producing the highest voltages (1.1–1.2 V). Short circuit current increases with salt concentration up to approximately 30% (0.3 M), which is the saturation point, beyond which ion mobility decreases. This study demonstrates that electrode geometry and surface area significantly affect current density and internal resistance, while increased electrode spacing raises internal resistance and reduces maximum current output. These findings contribute to understanding the feasibility and performance characteristics of saltwater batteries as accessible energy sources using recyclable materials. Full article

3D concrete printing (3DP) enables automated construction with reduced material waste and enhanced geometric flexibility. However, its structural performance remains sensitive to anisotropy, mix design, and printing parameters, thereby complicating quality control. Self-sensing cementitious materials provide a promising approach by enabling intrinsic strain monitoring during fabrication and service. In this study, a hybrid multi-material printing strategy was developed using a conductive cement-based mix incorporating graphite (G), milled carbon microfibers (MCMF), and chopped carbon microfibers (CCMF), alongside a plain cement-based matrix. Based on percolation analysis, an optimal composition of 2 wt.% G, 0.25 wt.% MCMF, and 0.0625 wt.% CCMF was selected. Reinforced beam specimens were fabricated with the conductive material embedded in either the tensile (bottom) or compressive (top) region, combined with two internal architectures: diagonal infill and solid-base configuration. Four configurations were defined: Pattern 1 (bottom/diagonal), Pattern 2 (bottom/solid-base), Pattern 3 (top/diagonal), and Pattern 4 (top/solid-base). Cyclic three-point bending tests with spatially distributed electrical measurements were conducted to evaluate the electromechanical response in the elastic range. Specimens with the conductive layer located in the tensile region (Patterns 1 and 2) consistently exhibited higher gauge factors than those in the compressive region (Patterns 3 and 4). Pattern 2 exhibited the best sensing performance, with an average gauge factor of 556 and SNR of 31. Across all configurations, SNR decreased with increasing electrode spacing, with reductions of up to 31.0%, demonstrating the effect of current path length on sensing performance. Full article

Application of polyacrylonitrile-derived carbon fiber (CF) as a thermal insulation material is restricted by inherently high thermal conductivity. Encapsulation of poly(p-phenylene benzobisoxazole) (PBO) on CF was supposed to improve the mechanical and heat resistance of CF, which would be desired to improve mechanical and thermal-insulating performances. In this work, PBO molecules were uniformly coated onto the surface of air plasma-treated CF. Carbonized PBO-encapsulated CF (CF@CPBO) was prepared via thermal treatment at 600–1400 °C. At higher carbonization temperatures, CF@CPBO exhibited a cleaner surface, more radial graphite layers within fibers, enhanced crystallinity of carbon layers (amorphous to 0.337 nm of interplanar spacing), reduced defective/graphitic content (0.959–0.909 of I_D/I_G), decline in surface O content (20.1–9.6 at.%) and improved symmetry of the C-C deconvoluted peak. After weaving them into a net and compression molding, CF@CPBO felts with a random distributed structure (no voids and no fiber bundles) presented improved compression strength (10.5–25.6% of enhancement than unmodified CF) and excellent compression-recovery performance (130.9–110.8 MPa) through 10 cycles. Thermal conductivity values of CF@CPBO felts at 30–1800 °C were 0.13–1.42 W/m/K, which were 42.2–62.6% of unmodified CF. This work proposes an efficient strategy for regulating the high-performance organic fiber structure through heat treatment-induced processes. Full article

The paper presents the results of a study on the structure and electrical properties of graphite-like amorphous carbon films deposited by electron-beam evaporation with vacuum heat treatment. The current–voltage characteristics of the films were analyzed in weak and strong electric fields in the temperature range from 25 to 155 °C. For the contact of carbon films with nickel, the Schottky barrier height was calculated based on the obtained current–voltage characteristics. It was found that in the temperature range of 25–45 °C, the mechanism of direct tunneling of charge carriers through the narrow Schottky barrier dominates (φ_b = 0.055 eV). In the range of 55–75 °C, a transition to the thermally assisted tunneling mechanism is observed (φ_b = 0.076 eV). At temperatures above 85 °C, charge carrier transport through the Schottky barrier occurs via thermionic emission (φ_b = 0.3 eV). The analysis of the current–voltage characteristics of graphite-like carbon films allowed us to establish the main mechanisms of hopping conductivity via localized states. It is shown that in the temperature range of 298–348 K, conductivity is determined by states near the Fermi level. The temperature interval of 348–428 K corresponds to conductivity through the band tail of localized states near the conduction band. It is shown that the increase in conductivity in strong electric fields is due to the Poole–Frenkel effect. Full article

The development of efficient catalysts for acetylene hydrochlorination is critical for replacing the industrially prevalent mercury chloride catalysts. Herein, a defective nitrogen-doped carbon material (NC-APT) is engineered via a facile co-polymerization of pyrrole, aniline, and thiophene, followed by a controlled calcination procedure. This co-polymerization strategy introduces abundant structural defects compared to mono-polymerization processes, primarily due to the lattice mismatch and steric hindrance between the distinct monomers, which disrupts the regularity of the polymer chain and prevents graphitic ordering. The resulting NC-APT catalyst features a high specific surface area of 375.7 m²·g⁻¹ and a substantial nitrogen dopant content of 14.4%, with 81% of the nitrogen existing as catalytically active edge structures (pyrrolic and pyridinic N). Consequently, the catalyst delivers exceptional performance, achieving 92% acetylene conversion at 220 °C with a C₂H₂ gas hourly space velocity (GHSV) of 80 h⁻¹. This performance significantly outperforms many reported metal-free counterparts and rivals that of traditional metal-based catalysts. This work offers new insights into the rational design of carbon-based, metal-free catalysts through monomer mismatch engineering. Full article

The scalable and sustainable production of graphene remains a significant challenge due to the high cost, complex processing, and environmental impact associated with fossil-derived graphite precursors. In this work, we report a biorenewable pathway for producing graphitic carbon from industrial hemp biomass, yielding a plant-derived material called CleanGraphene. This approach provides a renewable and potentially scalable alternative to petroleum- and coal-based graphene production while maintaining competitive structural and electrical performance. CleanGraphene samples are systematically characterized using X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and thermogravimetric analysis (TGA) to evaluate crystallographic order, layer stacking, defect density, surface chemistry, and thermal stability. The results show that optimized CleanGraphene materials consist of multilayer graphene-like platelets with compact interlayer spacing (d(002) ≈ 3.36–3.37 Å), extended crystallite coherence lengths (L_c up to ~75 nm), large in-plane sp² domains (L_a exceeding ~200 nm), and relatively low defect densities, indicating well-developed graphitic ordering. Electrical conductivity measurements using a binder-free pelletization method and four-point probe analysis demonstrate that the highest quality CleanGraphene samples achieve conductivities of (8.4–8.6) × 10⁴ S m⁻¹, surpassing leading commercial graphene benchmarks measured under identical conditions. Structure–property correlations confirm that electrical performance is governed primarily by crystallite coherence, defect density, and interlayer stacking order, while surface oxygen content plays a secondary role within an ordered graphitic framework. All CleanGraphene samples exhibit excellent thermal stability, retaining more than 95% mass up to ~800–900 °C under an inert atmosphere. Collectively, these findings establish quantitative quality benchmarks for hemp-derived graphene and demonstrate that biomass-based graphene can achieve electrical and thermal performance comparable to, and in some cases exceeding, conventional commercial products. This work highlights industrial hemp as a promising renewable precursor for the scalable production of high-performance graphitic nanomaterials for electrically and thermally conductive composite applications. Full article

Bagasse, owing to its low cost and high carbon yield, is a promising precursor for hard-carbon anodes in sodium-ion batteries (SIB). Regulating the microcrystalline state and pore architecture during pyrolysis is key to boosting Na⁺ storage behavior. Here, the pyrolysis kinetics is controlled via stepwise carbonization to construct a defect-ordered island structure within the cellulose-derived carbon skeleton. Retaining sp³-hybridized carbon at low temperatures creates the Na⁺ channel, while acid cleaning selectively dissolves residual metal oxides, removing the electrochemical inert phase and promoting improved ion diffusion. This process also enriches active sites and interlayer spacing in the hard carbon, boosting capacity in the plateau region. In addition, the ash-catalyzed formation of local sp² graphite microcrystals provides electron transport nodes, optimizing Na⁺ diffusion and electronic conductivity. Accordingly, the assembled SIB achieves a high reversible capacity of 378 mAh g⁻¹ at 0.1C and an initial coulombic efficiency of 97%, with the plateau capacity accounting for 59.1% of the total reversible capacity. This work presents a universal thermochemical approach for engineering high-performance carbon anodes with high closed porosity from low-cost biomass precursors, advancing the development of sustainable and efficient SIBs. Full article

Metal substrates were preprocessed via picosecond laser surface texturing (PLST, 532 nm) to fabricate interfacial microgrooves for tribological performance optimization prior to deposition of a magnesium silicate hydroxide (MSH)/graphite/MoS₂–PI solid lubricant coating. By tuning the PLST parameters (average laser power: 0.2–0.5 W, scan passes: 3–5, hatch spacing: 0.005–0.1 mm), three representative texture geometries (linear, circular, and square) were produced, and the resulting coating performance was compared with conventional mechanical polishing and sandblasting pretreatments. Among the three laser textures, the linear texture exhibited the most excellent tribological performance and interfacial adhesion, outperforming the circular and square counterparts. Ball-on-disk tests in a kerosene-contaminated environment (10 N, 800 rpm) showed that the linear-textured sample reached the lowest steady-state friction coefficient (0.038), lower than polished (0.048) and sandblasted (0.052) controls, together with reduced wear scar dimensions. Progressive-load scratch tests indicated a pronounced adhesion enhancement, with the critical failure load increasing from 7.05 N (polished) to 26.05 N for the linear-textured interface, which is higher than 21.21 N (circular) and 23.78 N (square) textures. Cross-sectional microscopy and EDS mapping reveal that the laser-defined microgrooves (~15 μm depth, ~120 μm width, ~500 μm spacing) act as a parameter-controlled interfacial architecture that promotes mechanical interlocking and provides lubricant-rich reservoirs. This laser-enabled interfacial design suppresses delamination, supports transfer film stability, and ultimately enhances the coating’s tribological performance by reducing friction and wear. Full article