Journal of Powder Materials

Research Articles

[Korean]
Pressure-Dependent Resistivity of Commercial Nickel Powders with Different Morphologies and Sieve Classes for Pressure-Conductive Rubber Semiconductor Test Sockets: DongWook Lee, Moonjung Kim; J Powder Mater. 2026;33(5):379-387. Published online October 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00255

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Abstract PDF Supplementary Material: Pressure-conductive rubber (PCR) sockets rely on Ni powder fillers. We characterized four commercial Ni powders of two morphologies (spherical and dendritic) and two sieve classes (25–32 and 32–45 μm) using laser diffraction, N₂ adsorption, He pycnometry, scanning electron microscopy, and four-point powder resistivity at 2.6–25.7 MPa. Sieve subclassification had little effect on specific surface area, true density, or resistivity, whereas the spherical and dendritic groups differed markedly; as the two morphologies came from different suppliers, this is a combined morphology/supplier effect. Dendritic powders conducted in all three replicates at the lowest pressure (2.6 MPa), whereas spherical powders did so only from 10.3 MPa, with partial conduction at 7.7 MPa. At matched pressures, the groups differed by a factor of 16–70 (1.5 vs 86 mΩ•cm at 25.7 MPa). Despite lower packing fractions, dendritic powders had lower resistivity, consistent with contact topology, not packing density, governing conduction. With residual resistivity fixed at the bulk Ni value, the Montes compaction model described all specimens (R² = 0.986–0.996) with group-dependent exponents (n ≈ 2.1 dendritic, 3.2–3.9 spherical). These findings support using pressure-dependent powder resistivity to prescreen candidate Ni fillers before PCR socket prototyping.

[English]
Role of Oxides in the Tensile Properties of Pure Copper Processed by Laser Powder Bed Fusion: Haeum Park, Ki Jong Kim, Yeon Woo Kim, Hahun Lee, Kichul Park, Yerim Kim, Kee-Ahn Lee, Seok Su Sohn, Jeong Min Park; J Powder Mater. 2026;33(5):372-378. Published online October 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00248

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Abstract PDF: Oxide particles can affect the tensile properties of pure Cu processed by laser powder bed fusion (LPBF) through their interactions with dislocations. This study compared the microstructure and tensile behavior of samples produced from virgin and oxidized pure Cu powders under identical LPBF conditions. The two samples had comparable relative densities above 98.7% and similar grain sizes. Yield and ultimate tensile strengths were nevertheless higher in the oxidized sample, whereas uniform and total elongations were lower. Backscattered-electron imaging and image analysis indicated that oxide particles occupied a higher apparent area fraction in the examined fields of the oxidized sample; electron backscatter diffraction analysis also showed higher kernel average misorientation. Together, these observations suggest two possible roles for oxide particles: acting as dispersed obstacles to dislocation motion and promoting dislocation retention during LPBF, consistent with the higher kernel average misorientation. The strength increase may therefore reflect both particle strengthening and a greater contribution from dislocation strengthening.

[English]
Effect of Low-Oxygen Atmosphere Sintering on TiO₂ Powder Photoanodes for Fiber-Shaped Dye-Sensitized Solar Cells toward Carbon-Based Electrode Integration.: Yeonggwon Kim, Chae Young Woo, Sung Min Kim, Jiseong Park, Yongseon Jeong, Dabin Chun, Seungfeel Jeong, Hyung Woo Lee; J Powder Mater. 2026;33(5):327-337. Published online October 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00241

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Abstract PDF: Motivated by the goal of achieving high-temperature photoanode processing compatible with carbon-based current collectors, this study investigates the effect of sintering atmosphere on Ti wire/TiO2 photoanodes for fiber-shaped dye-sensitized solar cells. Photoanodes sintered under conventional air (Air) and a custom low-oxygen condition (LO, continuous Ar flow under reduced pressure at 500 °C) were compared, along with a subsequent low-temperature air-annealing treatment (LO-A). X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed no substantial difference between Air and LO, whereas X-ray photoelectron spectroscopy (XPS) showed a marked increase in reduced Ti species (Ti3+, Ti2+) and an approximately twofold higher C 1s signal for LO, accompanied by significantly reduced N719 dye adsorption. LO photoanodes exhibited short-circuit-like device behavior, precluding reliable photovoltaic characterization. Although LO-A eliminated this short-circuit behavior and largely restored dye adsorption, photovoltaic performance remained severely suppressed, and electrochemical impedance spectroscopy revealed a three-orders-of-magnitude increase in photoanode-related charge-transfer resistance relative to Air. These results indicate that dye-anchoring capacity and interfacial charge-transfer resistance are governed by at least partially distinct factors, possibly involving reduced Ti species, carbon residue, and leakage paths, whose contributions were not separated, and that low-temperature annealing alone is insufficient to restore the photoelectrochemical functionality compromised by LO sintering.

[Korean]
Microstructural Characteristics and High-Temperature Compression Behavior of a Ni-Based ODS-Composition Alloy and Refractory Composite: Song-Yi Kim, Do-Hun Kwon, Eun-Ji Cha, Hwi-Jun Kim; J Powder Mater. 2026;33(5):365-371. Published online October 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00234

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Abstract PDF: Nickel-based alloys have been widely used as high-temperature structural materials owing to their excellent oxidation resistance, phase stability, and mechanical reliability. However, their mechanical properties can rapidly deteriorate under ultrahigh-temperature conditions due to thermally activated dislocation motion, dynamic recovery, and grain-boundary-mediated deformation. Therefore, introducing thermally stable refractory constituents that retain high strength at elevated temperatures may provide an effective strategy for overcoming this limitation. In this study, Nb-Si-Ti-based refractory silicide alloy powder and Mo-based refractory alloy powder were introduced as reinforcing constituents to improve the ultrahigh-temperature deformation resistance of a Ni-based ODS-composition alloy. A Ni-MRC composite was fabricated by spark plasma sintering. The composite powder consisted of 65 wt.% Ni-based ODS-composition alloy powder, 25 wt.% Nb-Si-Ti-based refractory silicide alloy powder, and 10 wt.% Mo-based refractory alloy powder. Powder morphology, phase constitution, SPS-consolidated microstructure and ultrahigh-temperature compression behavior at 1050 °C were analyzed using SEM, XRD, EBSD, and Gleeble-based compression testing to evaluate the role of refractory reinforcements in improving the deformation resistance of the Ni-based matrix. The Ni-MRC composite exhibited a peak stress of 221 MPa at 1050 ℃, approximately 106% higher than that of the Ni-based ODS-composition alloy, indicating improved ultrahigh-temperature deformation resistance.

[English]
Thermite-Assisted Cu-Coated Al Powder as a Solid Propellant: Expanding the Use of Coarse Al Powder: Soo-ho Jung, Jinhee Bae, Ji Hun Yu, Ho sung Kim, Soo Hyung Kim; J Powder Mater. 2026;33(5):356-364. Published online October 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00206

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Abstract PDF Supplementary Material: Aluminum (Al) powder is a key fuel for solid propellants, but its native oxide (Al2O3) layer acts as a diffusion barrier, resulting in incomplete combustion. Although coarse Al powders offer excellent handling stability, their reactivity is considerably lower. To address this limitation, we coated Al powders with copper (Cu) by electroless plating to form a dual-layer shell with an outer Cu layer and an inner Al2O3 layer. During combustion, the Cu layer induces a thermite reaction at the powder surface, generating intense thermal stress that ruptures the dense oxide shell and promotes oxidation of the internal Al core. Thermogravimetric analysis and differential scanning calorimetry showed higher reactivity and significantly greater heat release in the Cu-coated Al (Cu/Al) powders. In combustion and propulsion tests, the 35 μm Cu/Al powder achieved maximum explosion pressures and pressurization rates comparable to those of pristine 5 μm Al powder, together with a higher specific impulse. This surface modification improves the combustion efficiency of coarse Al powders and offers a promising route to high-performance solid propellants. However, the reduced margin against electrostatic discharge must be considered during handling.

[Korean]
Corrosion Layer Removal from 304L Stainless Steel and Airborne Particle Generation and Filtration under Different Laser Scanning Conditions: Hyun Jong Yoo, Changkyoo Park, Jeoung Han Kim; J Powder Mater. 2026;33(5):348-355. Published online October 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00199

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Abstract PDF: Laser surface cleaning (LSC) can remove corrosion layers without chemicals or abrasives but releases airborne particles that require control for safe industrial use. We cleaned artificially corroded 304L stainless steel with a 1200 W nanosecond Nd:YAG laser using three scanning strategies: a single pass with a 1.8 mm hatch distance (LSC 1.8), 18 offset passes at 1.8 mm (LSC 1.8/18), and a single pass at 0.1 mm (LSC 0.1). Residual corrosion products remained after LSC 1.8, whereas LSC 1.8/18 and LSC 0.1 removed the corrosion layer. Peak particle number concentrations were 4.71 × 106, 7.67 × 106, and 8.25 × 106 #/cm³, respectively, and modal diameters ranged from 112 to 121 nm. After normalization by the thickness of the removed layer, peak concentrations differed by only about 1.4% between LSC 1.8/18 and LSC 0.1, indicating that the concentration difference was mainly associated with the amount of material removed. Transmission electron microscopy showed agglomerates of nanoscale primary particles joined by necks; energy-dispersive X-ray spectroscopy and selected-area electron diffraction identified Fe–Cr–O particles with a spinel structure consistent with (Fe,Cr)₃O₄. H13-grade high-efficiency particulate air filtration achieved particle removal efficiencies of 99.95–99.98% across all conditions.

[English]
Phase-Equilibrium-Guided Carbonyl Processing of Highly Active Nickel Powders: Seoung Uk Bae, Kyoung-Tae Park, Joo Hyun Park, Jae Hong Shin; J Powder Mater. 2026;33(5):338-347. Published online October 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00185

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Abstract PDF: Nickel powders with large specific surface areas are cost-effective alternatives to noble-metal catalysts for hydrogen-producing reactions, including methane reforming and ammonia decomposition. However, thermodynamic control of nickel carbonyl formation and decomposition is essential for producing catalytically active powders through the Mond process. In this study, we established a thermodynamic framework for carbonyl nickel production by combining Gibbs free-energy analysis, the Clausius–Clapeyron relation, and liquid–gas phase-equilibrium calculations for the reaction Ni + 4CO ↔ Ni(CO)₄. The resulting phase-equilibrium map identified operating windows for selective nickel carbonyl formation and subsequent decomposition. High-pressure carbonylation achieved 99.7% nickel conversion at 200 °C and 50 atm, whereas thermal decomposition at 300 °C and 1 atm yielded 57.9% nickel recovery. Scanning electron microscopy revealed needle-like nickel particles, suggesting a morphology favorable for catalytic applications. Process simulations captured pressure evolution and Ni(CO)₄ phase transitions, supporting rational selection between liquid- and gas-phase operating regimes. These findings indicate that phase-equilibrium-guided carbonyl processing offers a scalable route to high-activity nickel powder catalysts for hydrogen-production technologies.

[English]
Fabrication of Multilayer Core-Shell Structure for High Power Factor in Bi₂Te_2.7Se_0.3 Thermoelectrics: Su Min Eun, Jin Kyeong Shin, Se Been Jeong, Eui Seon Lee, Sung-Tag Oh, Byung Joon Choi; J Powder Mater. 2026;33(4):299-309. Published online August 31, 2026; DOI: https://doi.org/10.4150/jpm.2026.00192

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Abstract PDF: Bi₂Te₃-based thermoelectric materials are attractive near room temperature, but their performance is constrained by sensitive carrier-concentration control, strong crystallographic anisotropy, and compositional instability from volatile Te. Here, a multilayer core-shell structure was fabricated by conformally coating Bi₂Te₂.₇Se₀.₃ (BTS) powders with ZnO–TiO₂ layers using rotary-type powder atomic layer deposition (pALD), followed by spark plasma sintering. Two configurations with the same ~4 nm total oxide thickness were prepared: a ZnO/TiO₂ bilayer (ZT) and a ZnO/TiO₂/ZnO/TiO₂ multilayer (DZT), where multilayer denotes the deposition scheme rather than a directly imaged layered architecture. Electron microscopy confirmed uniform amorphous shells that were retained as continuous interfacial films after sintering. The oxide interfaces donated electrons to the matrix, raising the carrier concentration and effective mass while preserving mobility and thereby enhancing the electrical conductivity and power factor; simultaneously they scattered phonons and suppressed bipolar conduction, lowering the lattice thermal conductivity. DZT achieved the highest power factor, attributed to its different deposition configuration, whereas ZT exhibited the lowest thermal conductivity; the two coated specimens reached comparable figures of merit (zT) within the measurement uncertainty, both markedly exceeding uncoated BTS. ALD-based interface engineering thus decouples electronic and phononic transport in n-type Bi₂Te₃.

[Korean]
Effect of Milling-Time-Dependent Zirconia Contamination on the Microstructure and Mechanical Properties of Mechanically Alloyed Multicomponent Nb-Si-Ti Sintered Alloys: Deokhyun Han, Seo-Yu Lee, Jin-Seo Park, Jeong-Sik Moon, Jungjoon Kim, Youngkyun Kim, Byungmin Ahn; J Powder Mater. 2026;33(4):291-298. Published online August 31, 2026; DOI: https://doi.org/10.4150/jpm.2026.00178

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Abstract PDF: Multicomponent Nb-15Si-23Ti-3Cr-2Sn-2Al-2Hf-1B-0.5Y alloy powders were synthesized by high-energy ball milling using a zirconia chamber and balls for milling times of 0.5–12 h, and the effects of milling time on powder evolution, contamination behavior, and the resulting microstructure and mechanical properties of hot-pressed sintered specimens were systematically investigated. The dominant deformation mechanism shifted from flattening to cold welding and then to a fracture- dominated steady state with increasing milling time, and the particle size decreased sharply up to 4 h before stabilizing. Yield and composition analyses showed that zirconia contamination remained limited up to 4 h but increased sharply beyond 6 h owing to severe wear of the milling chamber and balls. Sintered specimens from powder milled for 4 h exhibited a homogeneous microstructure with finely and stably dispersed Nb5Si3 intermetallic phases and moderate hardness, whereas insufficient milling for 2 h left coarse, unreacted phases, and excessive milling for 12 h introduced substantial zirconia contamination that lowered density while raising hardness. These results indicate that a milling time in the range of 4–6 h offers a favorable balance between alloying efficiency and contamination control, with 4 h being preferred owing to its comparatively minimal zirconia contamination.

[English]
Mechanical Behavior of Aluminum Matrix Composites Reinforced with Nanoscale Carbon Nanotubes and Silicon Carbide: Kanhu Charan Nayak, Jiwon Lee, Kon-Bae Lee, Ke Jiang, Hyunjoo Choi; J Powder Mater. 2026;33(4):267-280. Published online August 31, 2026; DOI: https://doi.org/10.4150/jpm.2026.00164

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Abstract PDF: Lightweight aluminum (Al) matrix composites reinforced with carbon nanotubes (CNTs) and nanoscale silicon carbide (SiC) were fabricated using high-energy attrition milling, nitridation-induced self-forming consolidation (NISFAC), and hot pressing to improve mechanical performance through CNT/SiC hybrid reinforcement. Attrition milling refined the composite powders and promoted the incorporation of CNTs and SiC particles into the Al matrix, whereas NISFAC and hot pressing enabled near-full densification and effective interparticle bonding. Among the investigated compositions, Al/5CNT/3SiC showed the best mechanical performance, with a hardness of 197 HV, compressive yield strength of 432 MPa, compressive strength of 756 MPa, and Young’s modulus of 110 GPa. These improvements are attributed to the combined effects of load transfer, thermal-mismatch-induced dislocation strengthening, Orowan strengthening, and grain-boundary strengthening. Compared with values reported in the literature, the present composites showed competitive mechanical properties despite their relatively low reinforcement content. These findings indicate that CNT/SiC hybrid reinforcement combined with NISFAC and hot pressing is an effective route for producing dense, high-strength Al matrix composites.

[English]
Microstructural Evolution and Tensile Response of a Fe–15Cr Oxide Dispersion Strengthened Steel after Hot Rolling and Heat Treatment: Trung Thanh Pham, Woo-Hyeok Kim, Hyun-Cheol Kim, Jeoung Han Kim; J Powder Mater. 2026;33(4):281-290. Published online August 6, 2026; DOI: https://doi.org/10.4150/jpm.2026.00157

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Abstract PDF: Fe-based oxide dispersion-strengthened (ODS) are promising structural materials for Generation IV nuclear systems because of their high-temperature strength, radiation tolerance, and microstructural stability. However, their mechanical performance is difficult to optimize because it depends on a coupled relationship among alloy composition, powder processing, consolidation, thermo-mechanical treatment, oxide dispersion, and deformation substructure. In this study, a machine learning (ML) screening workflow was used to prioritize multi-component Fe–15Cr-based ODS candidates based on predicted yield strength, ultimate tensile strength, and total elongation, followed by experimental validation of the selected alloy. The investigated alloy was processed by mechanical alloying, hot isostatic pressing, hot rolling, and post-rolling heat treatment at 1100 °C for 24 h. Electron backscatter diffraction (EBSD) showed that the hot-rolled condition contained an ultrafine, heterogeneous, and sub-structured ferritic matrix, whereas heat treatment produced substantial grain coarsening, recovery, and a high-angle grain-boundary-dominated structure. The hot-rolled alloy exhibited very high room-temperature strength, with a yield strength of 820 MPa and an ultimate tensile strength of 2079 MPa, but limited elongation of 2.3%. At 650 °C, elongation increased markedly to 34.9%. After heat treatment, room-temperature elongation improved to 13.9%, although the yield and ultimate tensile strengths decreased to 680 MPa and 935 MPa, respectively.

[English]
Fabrication and Thermal Conductivity of Boron Nitride Nano Barb/Acrylic Polymer Nanocomposites: Hyojeong Lee, Jiyeon Koo, Eunsu Park, Hyunjoo Choi; J Powder Mater. 2026;33(3):230-238. Published online June 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00143

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Abstract PDF: The effect of manual mortar-grinding pretreatment on the thermal and mechanical properties of Boron Nitride Nano Barb (BNNB)-filled acrylic polymer composites was investigated. Composites incorporated with 5 wt.% (≈3 vol.%) of either virgin or mechanically fractured (shattered) BNNB were fabricated via hot-pressing of a thermoplastic acrylic resin at 230°C under 96 MPa for 90 min. Vickers hardness increased from 20.4 HV for neat acrylic to 29.2 HV (+43.1%) for the shattered BNNB composite, which is attributed to the omnipresent activation of barb-mediated mechanical interlocking within the polymer matrix. Thermal conductivity improved by 18.1% and 34.7% relative to neat acrylic for the Acrylic/Virgin BNNB and Acrylic/Shattered BNNB composites, respectively. The superior thermal performance is attributed to a phonon bridging network formed through barb-mediated contact between dispersed BNNB fragments, supported by experimental values exceeding Lewis–Nielsen model predictions. These results demonstrate that simple manual grinding simultaneously enhances mechanical and thermal properties without chemical surface modification, offering a practical strategy for thermally conductive polymer composite design.

[English]
Heat-Treatment-Induced Deformation Shift in LPBF-Fabricated Heterogeneous Microstructured Al–Zn–Mg–Cu Alloys: Jungho Choe, Ji Hun Yu, Jina Kwak; J Powder Mater. 2026;33(3):184-194. Published online June 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00136

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Abstract PDF: This study investigated the effect of T6 heat treatment on the tensile properties and deformation behavior of heterogeneous microstructured Al–Zn–Mg–Cu alloys fabricated by laser powder bed fusion. In the as-built state, pronounced microstructural heterogeneity, including non-uniform precipitate distributions and solute segregation concentrated in the coarse columnar grain (CCG) regions, promoted strain localization within the fine equiaxed grain (FEG) regions. This architectural imbalance produced a high ratio of hetero-deformation-induced (HDI) stress to overall flow stress. T6 heat treatment induced solute homogenization and more uniform precipitation across the matrix, together with grain growth that largely eliminated the distinct ultrafine equiaxed grain zones. These changes caused a clear hardness reversal between the FEG and CCG regions, shifting strain localization toward the CCG regions. Consequently, although the absolute magnitude of HDI stress increased with the higher flow stress, its relative contribution decreased because of the homogenized architecture. Despite reduced uniform elongation caused by early necking, overall tensile ductility improved substantially through suppression of premature intergranular cracking in the FEG regions, clarifying the relationship between microstructural evolution and deformation behavior.

[English]
Phase Formation Behavior and Piezocatalytic Properties of Sodium Bismuth Titanate-Based Perovskite Fine Powders Prepared by Ultrasonic Spray Pyrolysis: Hee Yeon Jeon, Jae Min Park, Ju Eun You, Young-In Lee; J Powder Mater. 2026;33(3):239-248. Published online June 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00129

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Abstract PDF: Sodium bismuth titanate (Na0.5Bi0.5TiO3, NBT) is a representative lead-free piezoelectric ceramic with ferroelectric and piezoelectric properties, promising candidate for piezocatalytic applications driven by mechanical vibration. In this study, NBT-based perovskite fine powders were prepared by ultrasonic spray pyrolysis (USP), a continuous aerosol process based on droplet-level reaction control. The effect of pyrolysis temperature, varied from 700oC to 950oC, on phase formation and particle morphology was investigated. At lower temperatures, Bi-based secondary phases predominated, whereas the perovskite phase gradually developed with increasing temperature. The powder synthesized at 950oC exhibited a well-defined perovskite crystal structure with improved crystallinity. FE-SEM analysis showed that the powders consisted of spherical particles with an average size of approximately 750 nm, without severe interparticle agglomeration. EDS analysis confirmed a relatively homogeneous distribution of Na, Bi, Ti, and O, with Na-rich composition, consistent with Na-rich precursor condition. Piezoresponse force microscope (PFM) measurements verified the ferroelectric and piezoelectric responses of the powder synthesized at 950oC. In Rhodamine B degradation tests under probe-type ultrasonication, adding the NBT-based powder increased the reaction rate constant from 7.96×10-3 to 1.16×10-2 min-1. These results suggest that USP is a feasible continuous process for preparing NBT-based perovskite fine powders for lead-free piezocatalytic applications.

[English]
A Powder-Metallurgical Route to Ag₂(Te,S) Compounds and Their Thermoelectric Properties: Seungki Jo, Yoojeong Ji, Linh Ba Vu, Kyung Tae Kim; J Powder Mater. 2026;33(3):214-220. Published online June 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00122

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Abstract PDF: Silver chalcogenides have attracted considerable attention as promising materials for wearable power generation because they combine mechanical ductility with favorable thermoelectric properties. However, most reported synthesis methods rely on high-temperature melting and annealing, which offer limited microstructural control and therefore restrict opportunities for further performance improvement. In this study, Ag2S0.4Te0.6 compounds were synthesized through a powder-metallurgical route that combined mechanical alloying with rapid densification by spark plasma sintering. Ball milling produced amorphized microscale powders, which were successfully consolidated at different sintering temperatures. The sample sintered at 600 °C exhibited the highest power factor, mainly because of its optimized electrical transport properties, and achieved zT values of approximately 0.32 near room temperature and approximately 0.50 at 473 K. These results indicate that powder-metallurgical processing is a viable strategy for tailoring transport properties and improving the thermoelectric performance of silver chalcogenide materials for wearable applications.

[Korean]
Aging Temperature Effect on the Microstructure and Mechanical Properties of Directed Energy Deposited Inconel 939 Alloy: Youngwoo Kim, Ye Chan Sung, Ho Seoung Kang, Jung Gi Kim; J Powder Mater. 2026;33(3):203-213. Published online June 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00115

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Abstract PDF: Directed energy deposition (DED) of Inconel 939 (IN939) alloy is useful for fabricating and repairing geometrically complex components used in gas turbine systems. Repeated laser scanning produces a non-equilibrium microstructure that can support high mechanical strength. However, because the microstructure of DED IN939 differs from that of conventionally manufactured IN939, it may evolve differently under the same post-heat-treatment conditions. Therefore, this study applied different aging temperatures to investigate the microstructural evolution and mechanical properties of DED IN939 alloys and to identify suitable post-heat-treatment conditions. Quantitative microstructural characterization showed that both the γ′ phase fraction and γ′ size increased as the first and second aging temperatures increased. Consistent with γ′ evolution under the different aging conditions, specimen strength was positively correlated with aging temperature, whereas elongation decreased because excessive γ′ formation and growth narrowed the γ′ channel width. Consequently, aging at 840 °C for 8 hours followed by aging at 740 °C for 8 hours provided the best combination of high strength and ductility in room-temperature tensile tests.

[English]
Interfacial Characterization of Al₂O₃-Coated p-Type Bi–Sb–Te Powders by Thermal and UV-assisted Atomic Layer Deposition: Jin Kyeong Shin, Yeongtae Choi, Byung Joon Choi; J Powder Mater. 2026;33(3):221-229. Published online June 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00108

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1 Citations

Abstract PDF

Interface engineering is an effective strategy for enhancing thermoelectric performance by modulating carrier and phonon transport at interfaces. Atomic layer deposition (ALD), which enables uniform, conformal, and thickness-controlled coatings, is particularly well-suited for this purpose. In this study, p-type Bi0.35Sb1.6Te3 (BST) powders were coated with Al2O3 using thermal ALD and UV-assisted ALD (UV-ALD) at 85 °C. Scanning electron microscopy showed that neither process substantially altered the morphology of the BST powders. However, particle size analysis revealed that the UV-ALD sample exhibited a greater tendency toward partial agglomeration, which may be associated with the more pronounced OH-related band observed in the Fourier-transform infrared spectroscopy results. Cs-corrected scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy mapping revealed continuous Al₂O₃-based coating layers approximately 2–3 nm thick on the BST particle surfaces, forming a core–shell structure. Fast Fourier transform analysis suggested that the coating layers were amorphous, and X-ray photoelectron spectroscopy indicated Al–O bond formation while the main chemical states of BST were preserved. These results demonstrate that both thermal ALD and UV-ALD can effectively deposit continuous amorphous Al₂O₃-based interfacial layers on BST powders, providing a structural basis for future studies of interface-engineered thermoelectric materials.

Citations

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Fabrication of Multilayer Core-Shell Structure for High Power Factor in Bi2Te2.7Se0.3 Thermoelectrics
Su Min Eun, Jin Kyeong Shin, Se Been Jeong, Eui Seon Lee, Sung-Tag Oh, Byung Joon Choi
Journal of Powder Materials.2026; 33(4): 299. CrossRef

[English]
Ultra-Low Temperature Mechanical Response of Laser Powder Bed Fusion–Processed C-Containing CoCrFeMnNi High-Entropy Alloy: Jae-Yong Cheon, Seong-June Youn, Young-Sang Na, Young-Kyun Kim; J Powder Mater. 2026;33(3):195-202. Published online June 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00101

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Abstract PDF: This study examined the microstructure and tensile behavior, from room temperature to 4.2 K, of a carbon-containing CoCrFeMnNi high-entropy alloy (HEA) fabricated by laser powder bed fusion (LPBF). Microstructural analysis revealed that the LPBF-built HEA comprised a single face-centered cubic (FCC) phase and exhibited epitaxial grain growth along the build direction. Dislocation cell structures and Cr-rich carbides were also observed within the grains. Tensile testing demonstrated a monotonic increase in both yield strength and ultimate tensile strength with decreasing temperature, and the LPBF-fabricated HEA consistently exhibited higher strength than its wrought counterpart across the entire temperature range investigated. Deformation twins were identified in all tested specimens, with the twin fraction increasing markedly at 4.2 K. These findings suggest that the excellent mechanical performance of the LPBF-fabricated carbon-containing CoCrFeMnNi HEA under ultra-low-temperature conditions is attributable to the combined effects of process-inherent microstructural features and pronounced deformation twinning.

[English]
Microstructure, Magnetic Properties, and Performance of Fe-6.5Si Soft Magnetic Core Produced by Laser Powder Bed Fusion: Ji Sang Yoon, Yeon Woo Kim, Gyu Hyun Park, Youk Jin Kim, Sang Heon Lee, Jeong Seok Kim, Sung Ho Yu, Jeong Min Park; J Powder Mater. 2026;33(3):177-183. Published online June 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00094

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Abstract PDF: High-silicon electrical steels containing 6.5 wt.% Si (Fe-6.5Si) are promising materials for high-efficiency electric motors because of their high electrical resistivity and low core loss. However, the intrinsic brittleness of high-silicon steels limits their formability using conventional fabrication methods, such as cold rolling, pressure forming, and sintering, making it difficult to fabricate three-dimensional (3D) soft magnetic cores for axial-flux permanent magnet (AFPM) motors. Additive manufacturing has recently attracted attention as an effective approach for producing complex magnetic components. In particular, laser powder bed fusion (LPBF) enables the fabrication of geometrically complex structures through localized melting and rapid solidification of metal powders. During LPBF, rapid thermal cycling can generate unique microstructures that influence the magnetic properties of fabricated materials. In this study, Fe-6.5Si samples were fabricated using LPBF, and their microstructure and magnetic properties were investigated. In addition, a complex-shaped 3D core was successfully fabricated by LPBF, and the performance of an AFPM motor equipped with the LPBF-fabricated core was evaluated. The results show that the LPBF-fabricated core can provide superior performance-to-weight efficiency for lightweight motor applications.

[English]
Effect of Compositional Trade-off Between Cr and Mo on the Corrosion Resistance of Additively Manufactured Co-Cr-Fe-Ni-Mo High-Entropy Alloys: Jeongmin Lee, Yeonghwan Song, Jae Hyuk Lee, Sung-Jae Jo, Minho Shin, Hyunbin Lim, Soon-Jik Hong, Soo-Hyun Joo; J Powder Mater. 2026;33(2):137-144. Published online April 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00087

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Abstract PDF: In this study, the corrosion behavior of Co-Cr-Fe-Ni-Mo high-entropy alloys additively manufactured via direct energy deposition was investigated according to the compositional trade-off between Cr and Mo elements. Two distinct alloy compositions were fabricated by adjusting the feeding rate of two powders with different chemical compositions through a dual nozzle. Electrochemical testing in a 3.5 wt% NaCl solution revealed that the Cr-rich and Mo-lean alloy exhibited inferior corrosion resistance compared to the Cr-lean and Mo-rich alloy. Specifically, the corrosion potential of the Cr-rich and Mo-lean alloy shifted negatively by approximately 200 mV compared to the Cr-lean and Mo-rich alloy, accompanied by an increase in corrosion current density and the pronounced initiation of localized pitting. This deterioration is attributed to a lack of passivation caused by the small amount of Mo in the Cr-rich and Mo-lean alloy. The passive film of the Cr-lean and Mo-rich alloy was more robust, characterized by a higher concentration of Mo, which effectively inhibited pit propagation through repassivation. These findings demonstrate that maintaining a critical Cr-Mo balance is more vital for the electrochemical stability of additively manufactured high-entropy alloys than unilateral Cr enrichment.

[English]
Analysis of Sintering Behavior and Microstructure of Mo-Ta Alloy under Different Sintering Conditions: Byungheon Oh, Geon Kim, Jio Yoon, Dongju Lee; J Powder Mater. 2026;33(2):130-136. Published online April 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00080

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Abstract PDF: Molybdenum-tantalum (Mo-Ta) alloy sputtering targets are widely used in electronic applications owing to their excellent corrosion resistance, high thermal and electrical conductivity, and low electrical impedance. In this study, the sintering behavior and microstructural evolution of Mo-Ta alloys fabricated by spark plasma sintering (SPS) were investigated as a function of sintering temperature in the range of 1650-1800 °C. X-ray diffraction and microstructural analyses indicate that densification and alloying of the mixed Mo and Ta powders occur simultaneously during the SPS process. Increasing the sintering temperatures significantly enhances densification, and the compact sintered at 1750 °C achieves a relative density exceeding 99%, which is essential for high-quality sputtering target applications. The sintered alloys exhibit a clear temperature-dependent grain growth behavior together with a homogeneous microstructure and randomly oriented grains. These results demonstrate that appropriate control of sintering temperature enables the fabrication of dense and microstructurally uniform Mo-Ta alloys, providing valuable guidelines for optimizing sputtering target performance.

[English]
Influence of Ta Addition on Austenite Stability and Strain-Induced Martensite Transformation in Sintered Fe-7Mn Alloy: Seunghyeok Choi, Sungjin Kim, Junho Lee, Seok-Jae Lee; J Powder Mater. 2026;33(2):119-129. Published online April 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00066

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Abstract PDF: This study examines the effect of Ta addition on austenite stability and strain-induced martensitic transformation behavior in Fe–7Mn alloys fabricated by powder metallurgy. Fe–7Mn–xTa alloys (x = 0, 1, and 1.5 wt.%) were produced via mechanical alloying followed by spark plasma sintering, achieving nearly full relative density for all compositions. With increasing Ta content, the initial retained austenite fraction significantly increased, reaching 80.55 vol.% in the Fe–7Mn–1.5Ta alloy. EBSD analysis revealed a grain coarsening tendency with Ta addition, indicating that the increase in retained austenite fraction could not be explained solely by grain refinement. Compression tests up to 20% strain showed strain-induced martensitic transformation in all alloys, with substantially more pronounced transformation observed in the Fe–7Mn–1.5Ta alloy. The Burke–Matsumura–Tsuchida model showed that the austenite stability parameter (k), where higher values indicate lower stability, increased from 3.89 to 10.62 with Ta addition. Ta thus exhibits a dual effect: promoting retained austenite after sintering while reducing its deformation stability. The hardening efficiency per unit martensite fraction decreased with Ta content, and a preliminary correlation between k and hardening efficiency suggests that austenite stability governs the mechanical response of Fe–Mn-based alloys.

[English]
Influence of Cobalt Content on Phase Formation and Morphology in Co-Zn-O Oxides: Deukhyeon Nam, Sungdo Yun, Bo Eun Choi, Chan Woong Na, Yoon Myung; J Powder Mater. 2026;33(2):104-112. Published online April 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00052

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Abstract PDF: Co–Zn–O–based materials have attracted attention for applications in energy storage and catalysis. In this study, the effects of cobalt incorporation on the crystal phase and particle morphology of Co–Zn–O oxides were investigated. ZnO-based oxides were synthesized using a reflux method, and the influence of cobalt content on phase formation and morphology was systematically evaluated. As the cobalt precursor concentration increased, scanning electron microscopy–energy dispersive X-ray spectroscopy confirmed higher cobalt incorporation. This compositional variation was accompanied by changes in particle morphology, including nanoparticles, disk-like structures, and occasional rod-like features. X-ray diffraction and Raman spectroscopy showed that samples with low cobalt content retained the wurtzite ZnO phase, whereas higher cobalt concentrations led to formation of a ZnO/ZnCo2O4 composite. X-ray photoelectron spectroscopy revealed comparable binding energies among samples, while differences in peak width suggested variations in the local coordination environment of cobalt. These results indicate that cobalt content significantly influences phase composition and particle morphology in Co–Zn–O oxides synthesized under reflux conditions.

[English]
Ultrasonic Nanocrystal Surface Modification of 3D Interconnected Heterostructured Complex Concentrated Alloys Produced by Liquid Metal Dealloying: Microstructural Evolution and Wear Behavior: Jumi Choi, Yeji Kim, Munsu Choi, Jae Hyuk Lee, Dong Jun Lee, Auezhan Amanov, Soo-Hyun Joo, Hyoung Seop Kim; J Powder Mater. 2026;33(2):91-103. Published online April 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00045

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Abstract PDF: This study investigates the effects of ultrasonic nanocrystal surface modification (UNSM) on the microstructural evolution and tribological performance of a three-dimensional interconnected heterostructured compositionally complex alloy fabricated by liquid metal dealloying (LMD). The as-LMD microstructure comprises an interconnected Cu-rich phase and a CoCrFe-rich ligament phase. Electron backscatter diffraction reveals pronounced severe plastic deformation near the surface after UNSM, characterized by subgrain formation and increased intragranular misorientation. The kernel average misorientation distribution reveals a pronounced depth-dependent deformation gradient, with dislocations preferentially accumulating at the interphase boundaries. Vickers hardness increases from approximately 100–120 HV in the as-LMD condition to greater than 270 HV at the surface after UNSM, and the hardening effect remains detectable to a depth of approximately 500 μm. Compressive residual stresses are concentrated within the surface-adjacent ~50 μm. The solid ligament phase exhibits higher compressive residual stress than the Cu-rich phase, reflecting phase-dependent deformation accommodation and stress partitioning. Reciprocating wear tests show a narrower wear track, a markedly reduced wear depth, and a lower and more stable friction coefficient after UNSM. Microscopy shows oxide-layer cracking and delamination in the as-LMD condition, whereas the UNSM-treated surface exhibits minor abrasive wear of the tribo-film without delamination.

[Korean]
Effect of Powder Preparation Method on the Microstructural Characteristics of Sintered W-7Ni-3Cu Heavy Alloy: Youngmin Kim, Ji Young Kim, Minju Son, Wonyong Kwon, Eui Seon Lee, Sung-Tag Oh; J Powder Mater. 2026;33(2):113-118. Published online April 30, 2026; DOI: https://doi.org/10.4150/jpm.2026.00038

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Abstract PDF: The effect of powder characteristics and sintering temperature on the properties of W-7Ni-3Cu is investigated. The heavy alloy powders were prepared by ball milling and hydrogen reduction of elemental metal or metal oxide powders. Microstructural analysis revealed that the powder mixtures reduced by hydrogen at 800oC consist of a trace amount of Ni4W phase along with the metal W phase and Ni-Cu solid solution. Additionally, compared to metal powder, the powder mixture using oxide as raw material exhibited a relatively fine particle size. The W-7Ni-3Cu alloys sintered using oxide powders had relative density of over 99%, whereas the specimens using metal powders as a raw material showed relatively low values of 87.8~98.2%. The Vickers hardness of the sintered specimens using oxide powder was 3.34–3.92 GPa, which was higher than that of 2.39–3.22 GPa measured when using metal powders. The observed results can be attributed to the relatively high density and the reduced grain size.

Critical Review

[English]
X-Ray Imaging of Solid-State Sintering and Laser Powder Bed Fusion: A Review of Process Monitoring and Defect Evolution: Wonjun Cho, Woobin Cho, Seongheon Park, Donghwan Son, Insung Han; J Powder Mater. 2026;33(2):145-158. Published online April 30, 2026; DOI: https://doi.org/10.4150/jpm.2025.00479

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Abstract PDF: X-ray imaging has become essential for understanding powder-based metal processing. In solid-state sintering, synchrotron tomography reveals particle rearrangement, neck growth, and pore evolution, clarifying how packing heterogeneity and particle-size distribution govern densification. In laser powder bed fusion, high-speed radiography captures microsecond-scale melt-pool behavior, including keyhole dynamics, vapor-jet entrainment, spatter formation, and bubble-mediated porosity, thereby enabling mechanistic links between processing conditions and defect generation. Nonetheless, current X-ray methods face trade-offs between spatial and temporal resolution and often remain qualitative. Integrating operando imaging with physics-based simulations and machine-learning models offers a path toward quantitative prediction and real-time control. This review summarizes recent progress and highlights key challenges and opportunities for advancing operando characterization of powder-based metal processes.

Research Articles

[English]
Structural, Electrical, and Optical Properties of Al–Mg Co-Doped ZnO Thin Films: Jong-Mu Kim, Jun-Seo Park, Jun-Ha Lee, Min-Woo Kim, Jung-Woo Lee; J Powder Mater. 2026;33(1):44-50. Published online February 28, 2026; DOI: https://doi.org/10.4150/jpm.2026.00031

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Abstract PDF: Al–Mg co-doped ZnO thin films were fabricated by a sol–gel spin-coating process to investigate the effect of dopant ratio on their structural, electrical, and optical properties. The total dopant concentration was fixed at 3 mol%, while the Al-to-Mg ratio was systematically varied in AlₓMg₀.₀₃₋ₓZn₀.₉₇O (0 ≤ x ≤ 0.03). X-ray diffraction analysis showed that the films maintained a hexagonal wurtzite structure with a preferred (002) orientation up to an Al concentration of 1.5 mol%, whereas higher Al contents resulted in a degradation of crystallinity due to exceeding the solid solubility limit of Al in the ZnO lattice. Hall effect measurements revealed a decrease in carrier mobility with increasing Al content, attributed to enhanced ionized impurity scattering, while the carrier concentration and electrical conductivity reached optimal values at an Al–Mg co-doping ratio of 1.5 mol%–1.5 mol%. All films exhibited high optical transmittance in the visible region, with the highest average transmittance of approximately 83% observed at the same composition. These results demonstrate that controlling the Al/Mg dopant ratio is crucial for optimizing the performance of ZnO-based transparent conducting oxide thin films.

[English]
The Optimization of L-PBF Process for Economical & High Performance Using SiO₂ Nanoparticle-Coated Non-Spherical Ti Powder: Taehu Kang, Ukju Gim, Sehun Kim, Jongik Lee, Sanghee Jeong, Jimin Han, Bin Lee; J Powder Mater. 2026;33(1):22-36. Published online February 28, 2026; DOI: https://doi.org/10.4150/jpm.2026.00024

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Abstract PDF: In laser powder bed fusion (L-PBF), a metal powder–based additive manufacturing process, pure titanium powders rely on expensive gas-atomized spherical powders, which poses a significant limitation of material cost. In contrast, non-spherical titanium powders are more cost-effective but their application in L-PBF is restricted their use due to poor flow property and high oxygen content. In this study, a powder mixing strategy with spherical titanium and hydrophobic SiO2 nanoparticle is proposed to improve the flowability and process stability of non-spherical Ti powders. After evaluating flow properties at various mixing ratios, a spherical-to-non-spherical Ti ratio of 4:6 was selected, with SiO2 nanoparticles added during mixing. The uniform distribution of oxide nanoparticles on the powder surfaces was confirmed by SEM and EDS. A maximum relative density of 99.7% was shown by specimens made with L-PBF under various processing parameters. The specimens obtained a tensile strength of 762.6 ± 3.8 MPa and an elongation of 22.1 ± 0.7% at a volumetric energy density of 71.4 J/mm³. This study demonstrates the application of low-cost non-spherical Ti powders in L-PBF is feasible and presents an effective way to simultaneously increase process stability and economic efficiency in titanium additive manufacturing.

[Korean]
Study on Particle Shape Control and Characterization of SUS316L Flake Powder Fabricated by Wet Milling Process: Jae Hyeok Wi, Si Hong Ryu, Seong Eui Lee; J Powder Mater. 2026;33(1):37-43. Published online February 28, 2026; DOI: https://doi.org/10.4150/jpm.2026.00017

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Abstract PDF: In this study, a particle shape control process was developed to fabricate flake-like SUS316L powders about 20 µm for application in semiconductor gas filters. The Flake powder was produced through a wet milling process using a Planetary Mill by varying the rotation speed, milling time, solvent, and polyvinylpyrrolidone (PVP) dispersant conditions. The fabricated powders were then characterized to evaluate their morphological and phase transformation behaviors. In the ethanol-based Planetary Milling process, as the rotation speed increased from 300, 400, 500 rpm, the powder morphology was observed to gradually change from spherical to flake-like due to the increase in milling energy. According to the XRD, as the rotation speed increased, a phase transformation from austenite to martensite occurred due to the increase in heat generation and collisions between the powder and balls. In addition, an increase in Full Width at Half Maximum (FWHM) was observed, indicating a decrease in crystallinity. Under different solvent and dispersant conditions, the addition of 5 wt% PVP to the deionized water (DI Water) solvent suppressed particle fracture and produced more uniform flake-like particles compared with the DI Water process without PVP. In addition, a smaller FWHM and reduced oxygen content were observed.

Critical Review

[Korean]
Smelting and Recycling of Vanadium: Ho-Sang Sohn; J Powder Mater. 2026;33(1):61-73. Published online February 28, 2026; DOI: https://doi.org/10.4150/jpm.2026.00010

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Abstract PDF: Global annual production of vanadium is approximately 100,000 tonnes; however, it remains a critical metal for steelmaking and modern industry. This study reviews the current status of vanadium smelting and recycling technologies. Approximately 90% of vanadium is produced as ferrovanadium (FeV) for use in steel alloys, although it is also utilized in titanium alloys, battery materials, and other applications. Both mineral ores and secondary waste resources serve as raw materials for vanadium production. These materials are typically subjected to roasting followed by acid or alkaline leaching to extract V₂O₅. Vanadium metal and FeV are produced from V₂O₅ primarily through aluminothermic reduction; alternatively, metallic vanadium can be manufactured via thermal reduction using Ca, Mg, or C, as well as by molten salt electrolysis. Crude vanadium is subsequently refined into high-purity metal through high-temperature vacuum treatment, electron beam melting, or molten salt electrolytic refining. Vanadium contained in steel scrap is recycled through re-melting in an electric arc furnace. Vanadium present in fly ash and spent catalysts is recovered using smelting processes similar to those applied to natural ores.

Research Articles

[English]
Effect of Bimodal WC Particle Size Distribution on the Mechanical Properties of WC–Mo₂C–Co Cemented Carbides: Jinwoo Seok, Jong Tae Kim, Juree Jung, Bin Lee, Junhee Han, Leeseung Kang; J Powder Mater. 2026;33(1):13-21. Published online February 28, 2026; DOI: https://doi.org/10.4150/jpm.2025.00500

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Abstract PDF: In this study, the influence of bimodal WC particle size design on the microstructure and mechanical properties of WC–27 wt.% Mo₂C–10 wt.% Co cemented carbides was systematically investigated. Bimodal hard-phase designs were realized by combining ultrafine WC (300 nm) and coarse WC (1.8 μm) at various ratios, followed by consolidation via spark plasma sintering (SPS). During sintering, Mo₂C preferentially dissolved into the Co-rich liquid phase due to its higher solubility than WC, forming a Co–Mo–C liquid. During sintering progresses, ultrafine WC selectively dissolved owing to its high interfacial energy, gradually transforming the liquid composition into a Co–Mo–W–C system. Owing to the short holding time and rapid cooling rate of SPS, the η-phase (M₆C) formed during sintering remained metastable. Meanwhile, selective dissolution–reprecipitation resulted in the formation of Mo₂C-based core–rim structures with W enrichment in the rim region as (Mo, W)₂C. As the fraction of ultrafine WC increased, the hardness increased from 1769 to 1997 kgf/mm2, whereas the fracture toughness exhibited an insignificant difference from 6.56 to 6.65 MPa•m¹ᐟ². Fracture behavior analysis revealed that crack deflection and crack bridging occurred at the Mo₂C core–rim interfaces, effectively suppressing straight crack propagation. These results demonstrate that the introduction of ultrafine WC plays a dominant role in enhancing mechanical performance, and that bimodal WC design combined with Mo₂C addition is a highly effective strategy for developing high-performance cemented carbides for machining

[English]
Microstruture and Mechanical Properties of Ti.Grade12-Ti/TiN/WC Composite Produced by Spark Plasma Sintering Process: Hyun-Su Kim, Su-Gwan Lee, Dinh Van Cong, Jun-Seo Park, Ha-Seung Ryu, Jin-Chun Kim, Seung-Ick Lee; J Powder Mater. 2026;33(1):1-12. Published online February 28, 2026; DOI: https://doi.org/10.4150/jpm.2025.00486

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Abstract PDF: Ti.Grade12 is widely used in chemical processing, power generation, and nuclear industries because of its excellent corrosion resistance and mechanical strength, enhanced by alloying elements such as Ni and Mo. Ceramic reinforcements such as TiN have been reported to significantly improve the surface hardness and wear resistance of titanium-based materials. Furthermore, nano-sized WC particles can suppress excessive intermetallic compound formation and stabilize the Ti matrix through grain boundary pinning and microstructural control mechanisms. However, strong interfacial bonding between Ti and ceramic reinforcements generally requires high temperatures and prolonged sintering times, which may induce undesirable secondary phase formation. Therefore, optimizing the mixing ratio of Ti, TiN, and WC is essential to achieve a homogeneous interface and a stable composite structure. In this study, a composite layered structure was fabricated on a Ti.Grade12 substrate using mixed Ti, TiN, and nano-sized WC powders via Spark Plasma Sintering. A composition of 60 wt% Ti, 35 wt% TiN, and 5 wt% WC formed a stable coating layer without secondary phases and achieved a micro vickers hardness of approximately 2400 Hv.

[English]
Microstructure and Properties Comparison of Pure Cu and Cu-5 wt.% Al₂O₃ Composite Processed by Spark Plasma Sintering: Dinh Van Cong, Dong-Wan Lee, Su-Wan Lee, Nguyen Minh Thuyet, Nguyen Viet Hoang, Jin-Chun Kim; J Powder Mater. 2026;33(1):51-60. Published online February 28, 2026; DOI: https://doi.org/10.4150/jpm.2025.00472

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1 Citations

Abstract PDF

This study compares the microstructure and properties of pure Cu and Cu-5 wt.% Al2O3 composites fabricated by spark plasma sintering under strictly identical processing conditions at 800-1000 °C. Pure Cu samples achieved near-full densification and exhibited a bimodal grain structure dominated by coarse grains with increasing sintering temperature. In contrast, the composite samples showed lower density and non-monotonic densification behavior, with a minimum relative density at 900 oC and significantly refined equiaxed grains due to strong grain-boundary pinning by nano Al2O3 particles. The higher fractions of high-angle boundaries and pronounced orientation disruption were observed in the composite samples, while high-resolution analysis confirmed the presence of grain-boundary Al2O3-rich regions that restricted Cu grain coalescence and continuity of grain boundary migration. X-ray diffraction results confirmed the absence of reaction phases in both materials. Hardness peaked at 900 °C for both samples, and the composite samples showed consistently lower hardness due to retained porosity. The apparent electrical conductivity of the composite displays a non-linear temperature dependence, reflecting the competing influences of densification, microstructural recovery, and the insulating nature of Al2O3.

Citations

Citations to this article as recorded by

Microstructure and properties of Cu matrix composites reinforced with WMoTaNb refractory high-entropy alloy nanoparticles fabricated by spark plasma sintering
Baoguang Zhang, Yuanping Huang, Jian Wang
Vacuum.2027; 255: 115819. CrossRef

Critical Review

[Korean]
Research Trends in Magneto-Mechano-Electric (MME) Energy Harvesting Devices: So Ie Jeong, Geon-Tae Hwang; J Powder Mater. 2025;32(6):529-541. Published online December 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00493

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1 Citations

Abstract PDF

Magneto-mechano-electric (MME) energy harvesters have emerged as a promising solution for maintenance-free power generation in rapidly expanding Internet of Things (IoT) environments, where replacing or wiring batteries is impractical. MME devices convert weak alternating magnetic fields, ubiquitous around power infrastructures, into useful electrical energy through sequential magnetic, mechanical, and electrical transduction processes. This review summarizes recent advances across triboelectric-, piezoelectric-, and hybrid MME architectures. Triboelectric MME generators employing nano-engineered polymer surfaces, flash-induced surface modification, and nanoscale pattern replication demonstrate low-cost fabrication routes while achieving significantly enhanced voltage and current outputs. Piezoelectric MME systems based on Mn-doped PMN-PZT single crystals highlight strategies for improving mechanical quality factors and resonance-driven power generation. Further, hybrid MME designs that integrate piezoelectric and electromagnetic induction mechanisms enable high-power outputs exceeding tens of milliwatts, sufficient to operate multifunctional IoT platforms and charge practical energy-storage devices. Collectively, these studies illustrate a transition of MME harvesting technologies from laboratory concepts to application-ready self-powered systems. Future opportunities lie in broadband resonance design, modular harvester integration, advanced power management, and multi-source hybridization for robust long-term operation in real environments.

Citations

Citations to this article as recorded by

Microstructure, Magnetic Properties, and Performance of Fe-6.5Si Soft Magnetic Core Produced by Laser Powder Bed Fusion
Ji Sang Yoon, Yeon Woo Kim, Gyu Hyun Park, Youk Jin Kim, Sang Heon Lee, Jeong Seok Kim, Sung Ho Yu, Jeong Min Park
Journal of Powder Materials.2026; 33(3): 177. CrossRef

Research Articles

[English]
A Self-Powered Cationic Microfiber-Based Triboelectric Air Filter for High-Speed Particulate Matter Removal and Smart Monitoring: Tae-hyung Kim, Jin-Kyeom Kim; J Powder Mater. 2025;32(6):481-491. Published online December 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00465

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1 Citations

Abstract PDF

Particulate matter (PM) pollution demands air filters that combine high efficiency with low pressure drop. Here, we report a self-powered electrostatic filter based on an electrospun cationic microfiber web of Chimassorb 944 (C-fiber). The C-fiber functions as a triboelectric nanogenerator (TENG), generating a surface charge density of 85.8 85.8 μC/m2 when paired with polytetrafluoroethylene (PTFE), which creates a strong electrostatic field for capturing sub-micron particles, including the most penetrating particle size (MPPS). As a result, the triboelectrically charged C-fiber filter maintains >80% filtration efficiency at a high wind speed of 60 cm/s, far exceeding uncharged mechanical filters (<20%) while retaining low air resistance. Kelvin probe force microscopy (KPFM) visualizes the surface-potential change after particle capture, and the gradual decay of TENG output provides a built-in indicator of dust loading. This strategy offers a promising platform for next-generation smart air purification systems.

Citations

Citations to this article as recorded by

Self-powered triboelectric electrospun air filters as functional fibrous materials: Experiment-supported modeling of dielectrophoretic capture and scale-up
Tae-hyung Kim, Sangyul Baik, Doojoon Jang, Jin-Kyeom Kim
Materials Today Communications.2026; 56: 115941. CrossRef

[Korean]
Preparation of Porous W-Cu by Freeze Casting of Tert-butyl Alcohol Slurry Mixed with WO₃-CuO Powder: Youngmin Kim, Ji Young Kim, Minju Son, Wonyong Kwon, Eui Seon Lee, Sung-Tag Oh; J Powder Mater. 2025;32(6):466-471. Published online December 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00437

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Abstract PDF: The influence of process conditions on the microstructure of porous W-Cu, fabricated by freeze casting using tert-butyl alcohol as the freezing agent, was investigated. The slurries containing 10 vol% of WO3-CuO powder were prepared by milling with a small amount of citric acid and polyethylene glycol as dispersants. The slurries with dispersion stability were frozen in a mold with the lower part cooled to -25°C, followed by sublimation in a vacuum to remove the freezing agent. The sintered W-1 vol% Cu in a hydrogen atmosphere exhibited aligned pores with the size of 50 μm, which were generated by sublimation of directionally solidified tert-butyl alcohol crystals. In the cross-section of the specimen, hexagonal pores corresponding to the crystal structure of tert-butyl alcohol was observed. Microstructure analysis of the struts revealed that Cu was distributed non-uniformly due to the mutual insolubility and low wettability of the W-Cu system.

[Korean]
Comparison of the Properties of Rare-Earth Zirconate Thermal Barrier Coatings for Hydrogen-Fueled Gas Turbines: Gun-Woong Lee, Min-Soo Nam, Min-Ji Kim, HyunSuk Jung, Seongwon Kim; J Powder Mater. 2025;32(6):472-480. Published online December 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00423

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Abstract PDF: Thermal barrier coatings (TBCs) for hydrogen-fueled gas turbines withstand higher combustion temperatures and increased steam concentrations compared to conventional natural-gas systems. These harsh operating conditions significantly accelerate the thermal degradation of widely used YSZ coatings, emphasizing the need for alternative top-coat materials with improved phase stability and reduced thermal conductivity. In this study, rare-earth zirconate ceramics, Gd2Zr2O7 (GdZO), Tm2Zr2O7 (TmZO), and a mixed composition (Gd0.5Tm0.5)2Zr2O7 (Gd/TmZO), are synthesized and investigated as potential next-generation TBC candidates. Each material was comparatively examined with a focus on crystal structure, thermophysical properties, and thermal conductivity. Furthermore, high-temperature steam exposure experiments were performed to simulate hydrogen combustion environments. Microstructural analyses, high-temperature degradation behavior, and phase stability evaluations were carried out to obtain fundamental experimental data. This study provides essential baseline information for the design and development of high-performance TBC materials suitable for the hydrogen-fueled gas turbine systems.

[Korean]
Enhancement of the Electrochemical Performance of SiOx Anodes by Al₂O₃ Coating via Powder Atomic Layer Deposition: Donggeon Shin, Yoonsoo Han; J Powder Mater. 2025;32(6):501-508. Published online December 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00416

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1 Citations

Abstract PDF

Silicon based anode materials offer high theoretical capacity but suffer from severe volume expansion and unstable interfacial properties during repeated lithiation and delithiation, resulting in rapid performance degradation. In this study, a thin aluminum oxide coating layer was deposited on Si/SiOx Carbon anode materials using a powder atomic layer deposition (PALD) process to address these limitations. EDS mapping and XRD analyses confirmed the uniform formation of an amorphous aluminum oxide coating with increasing thickness as the deposition cycles increased. Electrochemical evaluation showed that the electrode coated with 5 PALD cycles exhibited approximately 78% higher capacity retention after 100 cycles at 1 A g-1 and a higher initial Coulombic efficiency compared to the bare electrode. The coated electrode also delivered approximately 22% higher capacity at a high current density of 5 A g-1, indicating enhanced rate capability. Cyclic voltammetry analysis revealed increased surface controlled reaction contributions and improved reaction kinetics. These results demonstrate that PALD derived aluminum oxide coatings effectively stabilize the electrode electrolyte interface and enhance the electrochemical performance of silicon based anodes, highlighting their potential for next generation high capacity lithium ion batteries. generation high capacity lithium ion battery anode materials.

Citations

Citations to this article as recorded by

AlN-PVDF composite protective coating for stabilizing lithium metal anodes in lithium metal batteries
Seul Ki Choi, Yun Seung Nah, Minho Yang
Carbon Letters.2026; 36(5): 2379. CrossRef

[English]
Finite Element and Discrete Element Analyses of Anisotropic Powder Compaction for Axial Flux Motor Cores: Jeong Ah Lee, Do Won Lee, , Hyojeong Ha, Ki Hyuk Kwon, Eon Byeong Park, Taeyoung Kim, Hyoung Seop Kim; J Powder Mater. 2025;32(6):451-458. Published online December 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00409

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1 Citations

Abstract PDF

This study investigates the compaction behavior of anisotropic, plate-like powders used in axial flux motor cores through a combined FEM–DEM approach. A porous continuum FEM model captures stress and density evolution during die pressing, revealing strong gradients along the compaction direction, with higher stress and densification near the upper punch and reduced compaction in the lower region. Guided by these results, DEM simulations examine particle packing, orientation, and contact pressure in representative zones. The DEM analysis shows that higher local pressure promotes denser packing and in-plane particle alignment near the upper punch, while the lower region exhibits more random orientations and lower contact forces. As a result, the multi-scale FEM–DEM framework clarifies how anisotropic particle behavior governs local densification and offers practical guidance for die design and process optimization to achieve more uniform density and controlled magnetic-property-relevant particle alignment in axial flux motor cores.

Citations

Citations to this article as recorded by

Microstructure, Magnetic Properties, and Performance of Fe-6.5Si Soft Magnetic Core Produced by Laser Powder Bed Fusion
Ji Sang Yoon, Yeon Woo Kim, Gyu Hyun Park, Youk Jin Kim, Sang Heon Lee, Jeong Seok Kim, Sung Ho Yu, Jeong Min Park
Journal of Powder Materials.2026; 33(3): 177. CrossRef

Critical Review

[Korean]
Smelting and Recycling of Niobium: Ho-Sang Sohn; J Powder Mater. 2025;32(6):517-528. Published online December 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00367

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2 Citations

Abstract PDF

Global annual production of niobium is only around 100,000 tonnes; however, it is a critical metal for modern industry and is mined in only a limited number of regions. This study reviews the current status of niobium smelting and recycling technologies. Approximately 90% of niobium is produced as ferroniobium (FeNb) for use in steel alloys, although niobium is also utilized in superalloys, superconductors, capacitors, semiconductors, and other applications. Niobium coexists with tantalum in columbite and tantalite ores. These ores are decomposed by hydrofluoric acid digestion or alkali fusion, followed by solvent extraction to separate Nb2O5 and Ta2O5. Niobium metal and FeNb are produced from Nb2O5 primarily via aluminothermic reduction, although metallic niobium can also be manufactured by thermal reduction using Mg, Ca, or C, as well as by molten salt electrolysis. Crude niobium is subsequently refined into high-purity niobium through molten salt electrolytic refining, high-temperature vacuum treatment, and electron beam melting. Because most niobium is used as an alloying element in stainless steel and high-strength low-alloy steel, recycling practices for niobium remain poorly documented.

Citations

Citations to this article as recorded by

Smelting and Recycling of Tantalum
Ho-Sang Sohn
Resources Recycling.2026; 35(1): 3. CrossRef
Smelting and Recycling of Vanadium
Ho-Sang Sohn
Journal of Powder Materials.2026; 33(1): 61. CrossRef

Research Articles

[Korean]
Microstructure and Mechanical Properties of AA3003 Tube for Heat Exchanger Processed by Floating Plug Drawing: Hyeon-Jun Heo, Sung Jun Oh, Seong-Hee Lee; J Powder Mater. 2025;32(6):459-465. Published online December 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00346

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Abstract PDF: An AA3003 tube was severely deformed by cold floating plug drawing, and then annealed at temperatures from 210 to 460℃. The as drawn Al tube exhibited a typical deformation structure in which the grains were greatly elongated along the drawing direction. The hardness increased with increasing the reduction of cross-sectional area (RA), became 68Hv after RA= 99%. Up to 310℃, the Al tube still mainly exhibited a deformed structure. While complete recrystallization occurred at temperatures above 360℃. The hardness decreased with increasing the annealing temperature, and it became 33Hv after annealing at 410℃. Both the tensile and yield strengths also decreased with increasing the annealing temperature, but the decrease was larger in yield strength than in tensile strength. The elongation increased with increasing the annealing temperature. The changes in the strength and the elongation with the annealing temperature were the largest at 360℃, in which the complete recrystallization occurred.

[Korean]
Ultrafast Synthesis of Molybdenum Disulfide via Flashlamp Annealing: Chan Hyeon Yang, Jaehak Lee, Jung Hwan Park; J Powder Mater. 2025;32(6):509-516. Published online December 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00339

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Abstract PDF: This study presents the synthesis of molybdenum disulfide (MoS₂) using flashlamp annealing and provides a comprehensive investigation of its structural and physical properties. The proposed flash-induced approach enables rapid production of high-quality MoS₂, offering superior process efficiency compared to conventional synthesis techniques. The structural, electronic, and thermal characteristics of the synthesized MoS₂ were systematically examined using multiple analytical methods, with particular attention to how synthesis conditions influence layer structure, crystallinity, and defect density. The results indicate that MoS₂ produced through this method exhibits material properties suitable for high-performance electronic devices and energy storage applications. Moreover, this work demonstrates the potential of flash-induced synthesis for scalable and practical fabrication of MoS₂-based nanomaterials, thereby contributing to the broader advancement of transition metal dichalcogenide technologies across diverse nanotechnology applications.

[Korean]
Laser-Induced Porous Graphene Electrodes for Flexible Heater: Min Gi An, Jaehak Lee, Jung Hwan Park; J Powder Mater. 2025;32(6):492-500. Published online December 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00332

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Abstract PDF: A flexible heater with high thermal efficiency and mechanical durability was developed by fabricating laser-induced porous graphene (LIPG) electrodes on polyimide films using a 532 nm green laser. Laser power, scan speed, and line distance were precisely optimized based on photothermal simulations to generate uniform porous graphene structures with large surface area and excellent heat dissipation characteristics. Raman, X-ray diffraction, and X-ray photoelectron spectroscopy analyses confirmed that the optimized LIPG exhibited highly graphitized features with low oxygen defects. Scanning electron microscope analysis revealed that porous morphologies formed only within a specific laser scan speed range, whereas excessive or insufficient irradiation resulted in collapsed or absent porosity. The serpentine-patterned LIPG heater maintained stable electrical resistance under repeated multidirectional bending, demonstrating excellent flexibility and mechanical stability. The heater also achieved rapid and uniform heating up to 80 °C within seconds, maintaining consistent temperature distribution even on curved surfaces.

[Korean]
Optimization of Mechanical Properties in WC–Mo₂C–Co Cemented Carbides via Dual Hard-Phase Based Heterogeneous Microstructure Design: Jinwoo Seok, Jong Tae Kim, Juree Jung, SongYi Kim, Bin Lee, Junhee Han, Leeseung Kang; J Powder Mater. 2025;32(5):428-436. Published online October 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00297

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1 Citations

Abstract PDF

WC–Mo₂C–Co cemented carbides were fabricated to investigate the effects of Mo₂C addition on microstructure and mechanical properties. Dual hard-phase design using WC and Mo₂C was employed to optimize the balance between hardness and toughness. Spark plasma sintering (SPS) was conducted at various temperatures after ball milling, and 1300 °C for 5 min was identified as the optimized sintering condition, achieving complete densification and phase stability. The addition of Mo₂C refined the microstructure by suppressing abnormal WC grain growth through preferential dissolution of Mo₂C into the Co binder. Hardness increased up to 1769 Hv30 due to grain refinement and solid-solution strengthening, while promoted η-phase formation and reduced fracture toughness.The 27Mo₂C composition exhibited the most balanced combination of hardness and toughness. These results demonstrate that controlled Mo₂C addition enables dual hard-phase strengthening and microstructure optimization in WC–Mo₂C–Co carbides for advanced cutting and forming applications.

Citations

Citations to this article as recorded by

Effect of Bimodal WC Particle Size Distribution on the Mechanical Properties of WC–Mo2C–Co Cemented Carbides
Jinwoo Seok, Jong Tae Kim, Juree Jung, Bin Lee, Junhee Han, Leeseung Kang
Journal of Powder Materials.2026; 33(1): 13. CrossRef

[Korean]
Powderization Strategy for Porcine Organ By-Products: A Comparative Study on the Effects of Drying Method and Polymer Additives: Seo Wan Yun, Eun Ju Jeong, Eui-Cheol Shin, Hyun-Wook Kim, Kyeong Soo Kim; J Powder Mater. 2025;32(5):416-427. Published online October 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00269

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Abstract PDF: This study aimed to develop a powderization strategy using porcine by-products (kidney, liver, and heart) by evaluating the effects of raw material type, pretreatment, and additives (hydroxypropyl methyl cellulose P645 and gelatin) on powder characteristics. Powders from kidney tissue were analyzed for yield, particle structure, compressibility, and size distribution, based on the drying method and additive composition. The spray-dried sample with gelatin at 1:0.5 (w/w) showed 20.4% compressibility and the smallest, most uniform particles, indicating excellent flowability. Due to its superior structural stability, gelatin was selected over HPMC P645. Liver and heart samples that underwent enzymatic hydrolysis and the Maillard reaction were spray-dried with gelatin and assessed for yield and microstructure. The Alcalase-treated liver sample showed the highest yield. Surface analysis confirmed that gelatin formed a protective film enhancing particle stability. These findings suggest gelatin-based spray drying is effective for producing high-quality powders from protein-rich by-products.

[Korean]
Enhanced H₂S Gas Sensing Using ZnO Porous Nanorod Synthesized via a Rotational Hydrothermal Method: Jimyeong Park, Changyu Kim, Minseo Kim, Jiyeon Shin, Jae-Hyoung Lee, Myung Sik Choi; J Powder Mater. 2025;32(5):406-415. Published online October 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00262

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Abstract PDF: In this study, ZnO porous nanorods were synthesised using a rotational hydrothermal process, and their performance as hydrogen sulphide (H2S) gas sensors was analysed. Compared to commercial ZnO nanoparticles and conventionally hydrothermally synthesised ZnO nanorods, the ZnO porous nanorods exhibited a more uniform structure and improved crystal growth in the (002) plane, with surfaces rich in porosity and oxygen vacancies. These structural and chemical characteristics significantly improved the sensitivity toward H2S, showing high detection performance at 250°C across various concentrations of H2S gas. Additionally, the sensor demonstrated excellent selectivity against other gases such as C2H5OH, C6H6, C7H8, and NH3. This study indicated that the rotational hydrothermal process is an effective method for developing high-performance ZnO-based gas sensors and suggests its applicability to other metal oxide materials.

[English]
Enhancing the Dispersion Stability of Exfoliated MoS₂ Nanoflakes for Na^⁺ Intercalation: Jae Min Sung, Dong-Won Kyung, Ammad Ali, Kee-Ryung Park, Mi Hye Lee, Da-Woon Jeong, Bum Sung Kim, Haejin Hwang, Leeseung Kang, Yoseb Song; J Powder Mater. 2025;32(5):390-398. Published online October 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00255

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Abstract PDF: This study investigated the dispersion stability of exfoliated MoS₂ nanoflakes in various organic solvents and binary mixtures using a Turbiscan optical analyzer. Sedimentation behavior was quantitatively evaluated via transmittance variation (ΔT), backscattering variation (ΔBS), and the Turbiscan stability index (TSI). Alcohol-based solvents were categorized by hydrophilic-lipophilic balance values. Long-chain alcohols, such as 1-undecanol, showed increased stability due to high viscosity and strong hydrophobic affinity with MoS2 basal planes, while short-chain alcohols exhibited poor stabilization. Binary mixtures of isopropanol (IPA) and tetrahydrofuran (THF) were also assessed, with the 5:5 volume ratio showing the best stability profile, including the lowest TSI and minimal ΔT and ΔBS values. This improvement is attributed to synergistic interactions, as IPA stabilizes hydrophilic edge sites, while THF engages with hydrophobic basal surfaces. These findings highlight the importance of balancing physicochemical properties when selecting solvents to improve MoS2 dispersion for structural modification and electrocatalytic applications.

[English]
Morphological Control and Surface Modification Characteristics of Nickel Oxalate Synthesized via Oxalic Acid Precipitation: Eunbi Park, Jongwon Bae, Sera Kang, Minsu Kang, Suseong Lee, Kun-Jae Lee; J Powder Mater. 2025;32(5):375-382. Published online October 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00248

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Abstract PDF: Nickel is widely used in industrial fields such as electrocatalysis and energy storage devices. Although micron-sized nickel particles exhibit excellent mechanical durability, their low specific surface area limits their reactivity. We modified the surface of micron-sized nickel particles with nanostructured nickel oxalate and investigated the effects of the solvent dielectric constant, surfactant, and thermal treatment atmosphere on the resulting particle morphology and phase transformation. Rietveld refinement analysis confirmed that changes in the solvent dielectric constant led to increased or diminished crystallinity of specific planes in nickel oxalate, resulting in diffraction patterns distinct from standard JCPDS data. These structural changes were also found to influence the morphology of the synthesized nickel oxalate. The results demonstrate that nickel oxalate serves as an effective precursor for producing Ni and NiO phases, and shape control of the final product can increase the surface reactivity of micron-sized nickel materials.

[English]
Preparation of Flake-shape Cobalt Powders by High-Energy Ball Milling for rSOC Current Collectors: Poong-Yeon Kim, Min-Jeong Lee, Hyeon Ju Kim, Su-Jin Yun, Si Young Chang, Jung-Yeul Yun; J Powder Mater. 2025;32(5):383-389. Published online October 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00241

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Abstract PDF: Reversible solid oxide cells (rSOCs), which enable two-way conversion between electricity and hydrogen, have gained attention with the rise of hydrogen energy. However, foam-type current collectors in rSOC stacks exhibit poor structural controllability and limited electrode contact area. To address these limitations, this study aimed to convert spherical cobalt powders into flake-type morphology via high-energy ball milling, as a preliminary step toward fabricating flake-based current collectors. Milling parameters—specifically, the ball-to-powder ratio (BPR), milling time, and process control agent (PCA) content—were varied. At an 8:1 BPR, over 90% of the powder became flake-shaped after 8 hours, while extended milling caused cold welding. In contrast, a 10:1 BPR resulted in dominant fragmentation. The Burgio–Rojac model quantified energy input and defined the optimal range for flake formation. Increasing the PCA to 4 wt% delayed flake formation to 16 hours and induced cold welding, as shown by bimodal particle size distributions. These results support the development of Co-based current collectors for use in rSOCs.

[Korean]
Synthesis and Morphology Control of Needle Type 513 MHSH and Mg(OH)₂ from Dolomite: Jiyeon Kim, HyunSeung Shim, Seong-Ju Hwang, YooJin Kim; J Powder Mater. 2025;32(5):399-405. Published online October 31, 2025; DOI: https://doi.org/10.4150/jpm.2025.00227

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Abstract PDF: 513 magnesium hydroxide sulfate hydrate (MHSH) and Mg(OH)₂ were synthesized by controlling the pH and concentration using a domestic resource, dolomite (CaMg(CO3)2), as the raw material. The MgSO₄ was extracted by treating dolomite with sulfuric acid under various conditions. Hexagonal plate-shaped Mg(OH)₂ and needle-like 513 MHSH were synthesized under the hydrothermal condition. The morphology of the synthesized materials was controlled by adjusting the pH (SO42-/OH- ratio) and hydrothermal reaction time. As the pH of the solution increased, the formation of plate-like structures became dominant, whereas lower pH values (higher SO42- concentration) led to needle-like forms. The results of the 513 MHSH, which was synthesized using reagents and sea bittern, are consistent with the synthesis conditions, and we observed changes in the length and aspect ratio of the needle-shaped structure in response to adjusting the hydrothermal reaction time.

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