Search Results (1,610)

Oleogel-based fat systems were developed using citrus fiber (CF) and cold-pressed pumpkin seed oil by-product (PSB) through an emulsion-template approach and evaluated as palm oil substitutes in a model chocolate sauce system. Oleogels were prepared by varying CF (4–5%) and PSB (0–2%) concentrations and characterized in terms of rheological, textural, and sensory properties and oxidative stability. The emulsions exhibited predominant elastic behavior (G′ > G″), with storage modulus (K′) values increasing from 694.12 to 2242.54 Pasⁿ as CF and PSB concentrations increased. Chocolate sauces formulated with CF–PSB oleogels showed pseudoplastic flow behavior and solid-like viscoelastic characteristics, with K′ values ranging from 89.32 to 356.56 Pasⁿ, compared to 34.84 and 16.95 Pasⁿ for the palm oil (C1) and sunflower oil (C2) controls, respectively. Temperature sweep and thermal loop tests demonstrated improved thermal resistance and emulsion stability in oleogel-containing chocolate sauces. Oleogel-based chocolate sauces also showed superior emulsion stability under thermal cycling and greater oxidative stability compared to the C2 sample. Texture profile analysis revealed increased hardness and spreadability with higher CF and PSB contents, consistent with rheological findings. Oleogel-based chocolate sauces also demonstrated enhanced oxidative stability, with induction period values reaching 18:55 h compared to 5:13 h for the sunflower oil control and approaching the palm oil control (20:13 h). Texture profile analysis revealed increased hardness and spreadability with higher CF and PSB contents. Sensory evaluation indicated that sauces containing 5% CF and 1–2% PSB received the highest scores for flavor, consistency, and overall acceptability. Full article

Copper azides are promising energetic materials for miniaturized pyrotechnic devices and micro explosive trains owing to their short detonation growth distance and high initiation energy. However, controllable preparation of copper nanoparticle precursors and their in situ conversion to copper azides under mild conditions remains challenging. In this study, copper nanoparticles were synthesized via a coordination-assisted aqueous reduction method at room temperature under air atmosphere using nitrilotriacetic acid disodium salt (NTA·H·2Na) as the complexing agent. The resulting nanoparticles were pressed into polyester rings to construct confined precursor structures, and copper azide micro-charges were prepared through in situ gas–solid reaction with HN₃ gas generated from NaN₃ and concentrated phosphoric acid at 60 °C. SEM characterization revealed that the morphological evolution of copper azides followed a three-stage pattern: “product island nucleation, branch/block coalescence growth, and continuous product layer formation and structural reconstruction”. Detonation velocity tests using the electrical probe method showed an average value of (5.10 ± 0.07) × 10³ m/s. Flyer impact initiation tests demonstrated that, with a charge thickness of 1.00 mm, both a 30 μm polyimide flyer and a 40 μm titanium flyer could successfully initiate a HNS–IV explosive. The preparation methodology and performance characterization established in this work provide an experimental basis for the application of copper azides in micro-initiation systems. Full article

The abnormal effect of hot isostatic pressing (HIP) on the fatigue properties of DD6 single crystal superalloy was investigated. The results showed that HIP combined with standard heat treatment (SHT) reduced the fatigue life under 880 °C and 800 MPa. HIP treatment eliminated inner shrinkage porosity effectively; however, the amount of micropores increased in the subsequent SHT. Moreover, HIP treatment enlarged the size of γ′ precipitates gradually and altered the morphology of carbides greatly. Small MC carbides decomposed into M₂₃C₆ carbides, and a serrated structure formed on the surface of large-size MC carbides, which led to the positive and negative effects on fatigue properties, respectively, depending on the morphology and size of carbides. Recrystallized microstructures were observed after HIP treatment, accompanied by fine, continuous precipitates along recrystallized grain boundaries. This led to a sharp decline in the elevated-temperature fatigue properties of DD6 superalloy fabricated at a drawing velocity of 150 μm/s. The abnormal decrease in fatigue life of DD6 single crystal superalloy was attributed to micropore formation, coarsening of γ′ precipitates and recrystallization. Thus, it is essential to optimize the HIP treatments in the future development of single crystal superalloy blades. Full article

Coffee is an important dietary source of bioactive antioxidant compounds contributing to the antioxidant properties of coffee beverages. While brewing affects yield of total antioxidants, it is still not really clear which individual (phenolic) compounds contribute to the antioxidant activity the most. A method combining chromatographic separation and individual antioxidant evaluation might therefore be useful. This study aimed at evaluating the antioxidant potential of the compounds in coffee beverages using a high-performance liquid chromatography approach directly coupled to the well-known trolox equivalent antioxidative capacity (TEAC) assay (HPLC-onlineTEAC). The study further evaluated the influence of different brewing methods (‘Americano’, ‘V60’, ‘French press’, and ‘cold brew’) on the bioactive compound profile and antioxidant potential of Arabica coffee beverages. The brewing method significantly affected caffeine content, chlorogenic acid composition, total phenolic content (TPC), and antioxidant activity of the analyzed beverages (p < 0.05). Cold brew samples exhibited the highest total radical scavenging activity and concentrations of major caffeoylquinic acid isomers (3-CQA, 4-CQA, and 5-CQA). In contrast, “French-pressed” beverages were characterized by the highest TPC values, while V60 samples generally showed the lowest antioxidant-related parameters. Chlorogenic acids accounted for more than 84% of the total antioxidant potential of all analyzed beverages, whereas monocaffeoylquinic acids represented the dominant fraction responsible for radical-scavenging activity. The results indicate that prolonged low-temperature extraction favors the recovery and preservation of highly reactive chlorogenic acid isomers and contributes to the enhanced antioxidant potential of coffee beverages, beyond the effect of coffee dose alone. Full article

Wittichenite (Cu₃BiS₃) was synthesized by mechanical alloying (MA) followed by hot pressing (HP), and its phase evolution, thermal stability, charge transport behavior, and thermoelectric performance were systematically examined. X-ray diffraction analysis of the MA powders revealed broadened diffraction peaks, indicating reduced crystallinity and refined crystallite size. After HP consolidation, a well-defined single-phase orthorhombic wittichenite structure was obtained. These results demonstrate that the mechanically induced solid-state synthesis was effectively initiated during MA and subsequently completed through crystallization, defect relaxation, and densification during HP. The MA–HP processed specimens exhibited high relative densities of 94–98% of the theoretical value and a homogeneous microstructure without detectable compositional segregation or grain-boundary enrichment, confirming the formation of a structurally and chemically stable single-phase bulk material. Thermal analysis identified a reversible polymorphic phase transition from P2₁2₁2₁ to Pnma at low temperature, followed by structural relaxation and the onset of partial decomposition at higher temperatures, indicating that Cu₃BiS₃ retains structural integrity below 700 K, which defines the relevant operating window for thermoelectric evaluation. The samples exhibited p-type semiconducting behavior, with electrical conductivity increasing with temperature due to thermally activated hole transport and showing an additional enhancement across the structural transition region. The Seebeck coefficient remained positive over the entire temperature range and decreased gradually with increasing temperature, consistent with semiconductor transport characteristics. The thermal conductivity remained low at 0.30–0.38 W·m⁻¹·K⁻¹, with a negligible electronic contribution, confirming that heat transport is dominated by lattice phonon scattering. As a result of the combined increase in electrical conductivity and intrinsically low thermal conductivity, the dimensionless figure of merit (ZT) increased continuously with temperature and reached 0.17 at 673 K. These results demonstrate that the MA–HP route provides an effective and scalable strategy for producing phase-pure Cu₃BiS₃ with controlled microstructure and reproducible thermoelectric performance. Full article

Soft magnetic composites (SMCs) are attracting increasing attention for electromagnetic applications owing to their three-dimensional shape flexibility and reduced eddy current loss. In this study, the 2-Pressing 1-Annealing (2P1A) process was applied to Fe–5.0 wt.%Si SMC toroidal cores to investigate the effects of pressing temperature and 1st pressing level on densification behavior, interparticle insulation structure, and frequency-dependent electromagnetic response. DEFORM-3D FEM simulations compared relative density distribution, hydrostatic stress, effective strain, and reaction load under single-press and 2P1A conditions. The 1st pressing stage was conducted at 350 °C with 30%, 50%, and 70% pressing levels, followed by final densification at 550 °C. Increasing compaction temperature reduced reaction load and hydrostatic stress range, while the 1st pressing level affected the final density distribution and stress state after 2nd pressing. TEM-EDS confirmed continuous interparticle insulation layers, and thickness measurements were used to compare local boundary structures. Among the 2P1A conditions, the 50% → 100% condition showed the smallest upper/lower relative density difference and the narrowest insulation-layer thickness range, indicating the most balanced condition in terms of densification uniformity and interparticle boundary structure. Compared with the 550 °C single-press condition, the 2P1A compacts showed higher permeability retention and Q-factor values in the 5–20 kHz range. These results indicate that the 1st pressing level influences staged densification behavior, interparticle boundary structure, and frequency-dependent electromagnetic response in Fe–5.0 wt.%Si SMC cores. Full article

The current need for thermal insulation building materials has led to the development of new materials and technologies, which are necessary to reduce carbon emissions. Lignocellulose materials are promising options for thermal insulation materials in construction, offering appropriate mechanical and environmental properties. While recent reviews focus primarily on material properties, a critical gap remains in the technical analysis of processing parameters and the comparative evaluation of alternative fabrication methods. This study provides a semi-systematic overview of manufacturing processes for lignocellulose-based thermal insulation, highlighting key production methods at the development stage: the most common hot pressing and compression molding, as well as less used hot drying, air-laid, wet-laid, needle-punching, and biological fabrication (mycelium-based). The results show that there is no single ideal method due to a fundamental trade-off: hot pressing provides superior mechanical strength, mycelium and needle-punching provide optimal thermal insulation, while room-temperature drying and blow-molding methods are the most environmentally friendly due to their minimal energy consumption. The key factors determining material performance are the material density, size, and type of raw material, which are strictly regulated by processing parameters. Full article

The growing accumulation of industrial waste and the depletion of natural mineral resources underscore the need for sustainable approaches to producing ceramic and construction materials. Among the most promising secondary raw materials are coal combustion by-products and metallurgical slags, which are suitable for ceramic applications. This review summarizes recent advances in the use of coal ash, blast furnace and steelmaking slags, together with clay-based raw materials, for the fabrication of ceramic and composite materials. Special attention is given to the physicochemical properties of technogenic raw materials and their effects on sintering, porosity, densification, mechanical strength, and thermal stability. Modern processing methods, including pressing and high-temperature firing, are also discussed. The influence of key technological parameters, such as oxide composition, particle size distribution, firing temperature, and activation conditions, is analyzed. In addition, the review examines major challenges related to raw material heterogeneity, structural instability, thermal stress development, cracking, free CaO reactivity, and environmental risks associated with heavy metal leaching. Recent studies show that incorporating industrial waste into ceramic systems reduces waste disposal, natural resource consumption, energy use, and CO₂ emissions, while promoting sustainable and resource-efficient technologies. Ash- and slag-based ceramics therefore remain highly promising materials for construction applications. Full article

In hybrid rolling bearings operating under extreme high-temperature and high-load conditions, steel rolling elements are prone to early failure, which has accelerated the widespread adoption of ceramic materials. To address the limitations of conventional studies, which have focused mainly on macroscopic wear parameters while neglecting subsurface failure mechanisms and the relationship among sintering process, microstructure, and fatigue performance, this work systematically compares the tribological behavior of Si₃N₄ ceramic balls fabricated by high-pressure electric resistance hot-pressing (REHP) and B₄C ceramic balls prepared by conventional hot pressing (HP) against 52100 steel counterparts. The central innovation of this study lies in clarifying, based on Hertzian contact theory and Lundberg-Palmgren life theory, that subsurface orthogonal shear stress, rather than surface compressive stress, is the fundamental driving force for contact fatigue failure of ceramic balls. In addition, two distinct damage evolution modes are revealed: B₄C exhibits early-stage brittle fracture and large-scale spalling, whereas REHP-Si₃N₄ is characterized by microcrack initiation and slow crack propagation. Moreover, the intrinsic mechanism by which the REHP process significantly enhances the contact fatigue life of ceramics is elucidated; namely, it refines grain size, eliminates residual porosity, and increases densification. The results show that, under the same high-load conditions, the mass loss of REHP-Si₃N₄ ceramic balls is only 35.7% of that of HP-B₄C, while the service life is extended by 20%. This work provides a key theoretical basis for ceramic material selection and sintering process optimization in high-performance hybrid bearings. Full article

Powder Bed Fusion–Laser Based (PBF-LB) represents the most-used metal Additive Manufacturing technology thanks to its capability of producing high-complexity geometries. The need for industries to define a qualification framework of additive components drew attention to post-processing approaches that can be applied to mitigate or reduce inherent defects. Among these post-processing approaches, Hot Isostatic Pressing (HIP) is recognized as one of the most effective techniques to address these challenges. Among materials employed with PBF-LB, especially in the aerospace sector, 316L stainless steel and the AlSi10Mg aluminum alloy are the most investigated, while among innovative copper alloys, there is GRCop42. Thus, the aim of this paper is to investigate the effects of low-temperature HIP on the tensile properties and microstructure of these materials. For this reason, tensile tests, metallographic analysis and X-ray computer tomography were conducted. The results highlight the influence of low-temperature HIP treatment with respect to the as-built condition. In particular, the Yield and Ultimate Tensile Strength for 316L and GRCop42 clearly improved, while for AlSi10Mg a relevant reduction was detected. However, an unexpected result was the reduction in the GRCop42 elongation that fell from ~10% down to ~2.5%, even though the porosity of the material was reduced to close to zero. Full article

Sodium-ion batteries (SIBs) are considered a promising alternative to lithium-ion systems, with hard carbon (HC) being the most suitable anode material due to its disordered structure and increased interlayer distance. At the same time, the recycling of polyethylene terephthalate (PET), whose waste volumes are constantly growing, remains a pressing issue. In this work, recycled PET is used as a precursor for obtaining HC by direct carbonization at temperatures of 900–1400 °C. It is shown that the carbonization temperature significantly affects the structure and electrochemical properties of the obtained materials. The best characteristics were demonstrated by samples PET_1000 and PET_1100, which provided a high reversible capacity of 275–280 mAh g⁻¹ at a current density of 20 mA g⁻¹ in sodium-ion half-cells. The results confirm that controlled carbonization of recycled PET is an effective approach for obtaining highly efficient anode materials for SIBs and, at the same time, represents a promising way to utilize plastic waste. Full article

Steelmaking produces large volumes of slag, a by-product with environmental risks due to accumulation and possible contamination. This study explores its use as a mineralizing agent in chamotte refractories. Slag rich in clinoferrisilite was added up to 5 wt.% to partially replace fine chamotte. Samples were shaped by semi-dry pressing and fired at 1350 °C. Chemical and phase composition, thermal behavior, microstructure, and physico-mechanical properties were analyzed. Results showed slag addition increased mullite content to 68 wt.% and promoted secondary magnesium–aluminosilicate phases (indialite, cordierite), indicating activation of reactions in the MgO-Al₂O₃-SiO₂ system. DSC and TGA revealed thermal effects between 1298 and 1325 °C, confirming slag’s fluxing role and lowering the liquid-phase sintering temperature. Optimal properties were achieved with 5% slag and 10% clay, yielding compressive strength of 24 MPa and apparent density of 2.30 g/cm³, meeting GOST 390-96 requirements for grade SHA. However, excess liquid-phase components reduce thermal stability. Thus, steelmaking slag is an effective secondary raw material, enhancing mullitization and refractory performance when used within controlled limits. Full article

Twelve white-rot fungal isolates were evaluated for their potential to produce mycelium leather from rice straw, based on growth characteristics, biomass production, and mechanical properties. Among these, Trametes sp. SW25-2 exhibited rapid growth on culture medium and dense mycelial formation on rice straw substrate. The effects of nutrient supplementation, substrate-to-medium ratio, and processing conditions on mycelium-leather formation were systematically examined. No significant differences were observed among different carbon (glucose, maltose, and sucrose) and nitrogen sources (yeast extract, peptone, and ammonium sulphate), indicating that the fungus effectively utilised rice straw as the primary substrate. An optimal ratio of 1 g rice straw to 10 mL culture medium (90.9% moisture content) enabled complete colonisation and the formation of a compact mycelial structure, achieving a maximum tensile strength of 2.78 MPa under optimised hot-pressing conditions (120 °C, 60 s, 1 MPa). Hot-pressing conditions significantly influenced material properties. A higher temperature (120 °C) increased tensile strength but reduced elongation at break, while a lower temperature (60 °C) produced more flexible materials. Scanning electron microscopy revealed that post-treatment and hot pressing transformed the mycelial network into a dense and cohesive structure. The resulting mycelium leather demonstrated suitable physical properties and was successfully fabricated into prototype products, highlighting its potential as a sustainable bio-based material derived from agricultural waste. Full article

All-cellulose composite (ACC) films, with their excellent tunable optical and mechanical properties, combined with biodegradability, represent a highly promising material for applications in the packaging and flexible electronics sectors. The optical properties of ACC films are critically governed by their microstructure, which is determined by drying conditions. In this study, the effects of drying conditions on the structure–property relationships of ACC films were systematically investigated. First, ACC films were fabricated via the partial dissolution of microcrystalline cellulose powder in ionic liquids, followed by a film-casting process. Subsequently, various drying conditions under different temperatures and pressures were applied to finalize the films. XRD characterization demonstrated the coexistence of cellulose I and cellulose II structures. Optical and morphological tests revealed that (1) drying without pressure resulted in obvious shrinkage and deformation, with the diameter reduced by 70%; (2) the high-temperature/high-pressure drying method promoted a dense structure, resulting in ACC films with high transmittance (>90%) and low haze (<10%); and (3) ACC films dried under different hot-press temperature conditions showed similar transmittance and a large difference in haze, which could be related to the micro-pores formed within films. The systematic correlation between structure and optical properties established in this work provides a clear pathway for the tailoring of the optical performance of cellulose films through controlled drying conditions. Full article

High-zinc blast furnace dust is a zinc-bearing solid waste generated during ironmaking. Efficient de-zincing and iron enrichment are required for its resource utilization. This study investigated the high-temperature reduction behavior and kinetic transition mechanism of cold-bonded briquettes made from high-zinc blast furnace dust with a small addition of iron ore powder, with particular emphasis on the effects of reduction temperature (1000–1200 °C) and holding time (10–60 min). The results show that reduction at 1200 °C for 60 min can effectively remove zinc and enrich iron. The de-zincing rate reached 92%, and the TFe grade increased to 50 wt.%, achieving the goal of efficiently removing zinc while improving the TFe grade of the reacted briquettes. During the middle and later stages of reduction (1100–1200 °C, 30–60 min), the content of newly formed metallic iron increased, which restored the briquette strength to 524 N after reduction. In addition, the reduction kinetics of the system evolved from interfacial chemical reaction control in the initial stage to three-dimensional internal diffusion control in the middle and later stages. These results provide a theoretical basis and technical reference for the resource utilization of high-zinc blast furnace dust. Full article