Journal of Powder Materials

[Korean]
New Chemical Technology by Using Nanocatalyst: Jin-Soo Hwang, Young-Kyu Hwang, Sung-Hwa Jhung, Jong-San Chang; J Korean Powder Metall Inst. 2006;13(2):85-101.; DOI: https://doi.org/10.4150/KPMI.2006.13.2.085

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[Korean]
Fabrication of Lightweight Aggregates Using Fly Ash from Coal Burning Heat Power Plant: Su-Jong Yoon; J Korean Powder Metall Inst. 2006;13(2):102-107.; DOI: https://doi.org/10.4150/KPMI.2006.13.2.102

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Abstract PDF: Recycling industrial wastes such as fly ash from a coal burning heat power plant and shell from an oyster farming were investigated to prevent environment contamination as well as to enhance the value of recycling materials. In this study, the lightweight aggregates and the red bricks were fabricated from fly ashes with other inorganic materials and wastes. The starting materials of the lightweight aggregate were fly ash powder and water glass, and the compacts of these materials were heat treated at 1100°C. The fabricated lightweight aggregates had low bulk density, 0.9-1.2;g/cm3, hence floated on the water and had the strength of 7.0-11.0 MPa and the modulus of 2900-3300 MPa which indicates it has enough strength as the aggregate. Another type of the light weight aggregate was prepared from fly ashes, shell powders and clays. The bulk density, porosity, and compressive strength of these aggregates were 1.19-1.34;g/cm3,;18.3sim56.1% and 5-12 MPa, respectively. The addition of a small amount of fly ash powder prevented hydration of the light weight aggregates. The red brick was also fabricated from the fly ash containing materials. It is suitable for the brick facing of a building as it has moderate strength and low water absorption rate.

[Korean]
Synthesis of Aluminum Hydroxide Nanofiber by Electrolysis of Aluminum Plates: S.H. Woo, M.K. Lee, C.K. Rhee; J Korean Powder Metall Inst. 2006;13(2):108-111.; DOI: https://doi.org/10.4150/KPMI.2006.13.2.108

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Aluminum hydroxides were synthesized by a simple electrolytic reaction of aluminum plates. The aluminum hydroxide, boehmite (AlO(OH)), was predominantly formed in the application of electrical potential at and above 30V, while the mixture of bayerite (Al(OH)_3) and boehmite (AlO(OH)) phases were formed below 20V. The boehmite has a clear fibrous structure controlled on nanometer scale. On the contrary, the bayerite consists of the typical hourglass or semi-hourglass shaped coarse crystals as a result of aggregation of various crystals stacked together. The specific surface area of the boehmite nanofiber was markedly high, approaching at about 302;m2/g.

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Experimental Study on Microwave Drying Aluminum Hydroxide
Xuemei Zheng, Fuqin Yuan, Aiyuan Ma, Shihong Tian
Coatings.2024; 14(6): 687. CrossRef

[Korean]
The Study of Charge Transfer Mechanism in Single Crystal Iron Perovskite: Young-Rang Uhm, Chang-Kyu Rhee, Chul-Sung Kim; J Korean Powder Metall Inst. 2006;13(2):112-118.; DOI: https://doi.org/10.4150/KPMI.2006.13.2.112

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Abstract PDF: [ R_1/3Sr_2/3FeO_3 ](R=Pr, Nd, and Sm) was synthesized and their magnetic properties and charge ordering(CO) transition related with lattice dynamics and oxygen vacancy were systematically investigated. The charge disproportion ation(CD) in R_1/3Sr_2/3FeO_3(R=Pr,Nd) was in which two kins of iron with valence state Fe3+ and Fe5+ were found with ratio of 2:1. In this charge ordering state a sequence of Fe3+Fe3+Fe5+Fe3+Fe3+Fe5+ exists aligned along the [111] direction of the pseudocubic perovskite structure. The charge ordering exist in distorted structure involving t_pd hybridization. The disordering phases coexist in distorted structure as temprature in creases that is controlled amount of oxygen vacancy. The magnetic hyperfine fields indicate charge tranfering temperature as it dissapeared drastically.

[Korean]
Grain Shape and Grain Growth Behavior in the Na_1/2Bi_1/2TiO₃-BaTiO₃ System: Kyoung-Seok Moon, Suk-Joong Kang; J Korean Powder Metall Inst. 2006;13(2):119-123.; DOI: https://doi.org/10.4150/KPMI.2006.13.2.119

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The grain growth behavior of 0.95Na_1/2Bi_1/2TiO_3-0.05BaTiO_3 (NBT-5BT) has been investigated with respect to the grain shape. The powder compacts of NBT-5BT were sintered at 1200 for various times. The corresponding equilibrium shape was a round-edged cube with flat 100-faces. Abnormal grains were not observed in the specimens sintered for 1 to 12 h but abnormal grains appeared when sintered for 24 h. Before the formation of abnormal grains, a valley was observed in the measured grain size distribution of NBT-5BT, showing that the grain size distribution was a combination of two unimodal distributions. The present result suggests that the grain growth in NBT-5BT was governed by the growth of facet planes which would occur via 2-dimansional nucleation and growth.

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Effect of Na₂CO₃ Addition on Grain Growth Behavior and Solid-state Single Crystal Growth in the Na_0.5Bi_0.5TiO₃-BaTiO₃ System
Kyoung-Seok Moon
Journal of Korean Powder Metallurgy Institute.2018; 25(2): 104. CrossRef

[Korean]
Powder Densification Using Equal Channel Angular Pressing: Seung-Chae Yoon, Min-Hong Seo, Sun-Ig Hong, Hyoung-Seop Kim; J Korean Powder Metall Inst. 2006;13(2):124-128.; DOI: https://doi.org/10.4150/KPMI.2006.13.2.124

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In recent years, equal channel angular pressing (ECAP) has been the subject of intensive study due to its capability of producing fully dense samples having a ultrafine grain size. In this paper, the ECAP process was applied to metallic powders in order to achieve both powder consolidation and grain refinement. In the ECAP process for solid and powder metals, knowledge of the internal stress, strain and strain rate distribution is fundamental to the determination of the optimum process conditions for a given material. The properties of the ECAP processed solid and powder materials are strongly dependent on the shear plastic deformation behavior during ECAP, which is controlled mainly by die geometry, material properties, and process conditions. In this study, we investigated the consolidation, plastic deformation and microstructure evolution behaviour of the powder compact during ECAP.

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Architectural design of advanced aluminum matrix composites: a review of recent developments
Behzad Sadeghi, Pasquale Cavaliere, Catalin Iulian Pruncu, Martin Balog, Moara Marques de Castro, Rajni Chahal
Critical Reviews in Solid State and Materials Sciences.2024; 49(1): 1. CrossRef

[Korean]
The Effect of Adittives on the Sintering Properties of Barium Titanate Powder Prepared by Self-propagating High-temperature Synthesis: Sung-Jae Lim, Chang-Yun Shin, Hyung-Il Won, Chang-Whan Won; J Korean Powder Metall Inst. 2006;13(2):129-137.; DOI: https://doi.org/10.4150/KPMI.2006.13.2.129

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Abstract PDF: In this study, high purity fine BaTiO_3 powders were prepared by SHS (Self-propagating High-temperature Synthesis). We would examinate the study of sintering properties and characteristics as a function of temperature with various additives (binder, sintering agent). In separately binder addition, the green and sintered density of specimen were increased as binder content increases. The increased porosity resulted in fine grain size due to the inhibition of grain boundary moving. The Al_2O_3,;TiO_2 and MgO playa role of increasing dielectric constants at room temperature. These values were decreased at curie temperature. In case of SiO_2, the Curie temperature was decreased. In this study, a high dielectric ceramic capacitor material with temperature stability was synthesized by using various additives.

[Korean]
Preparation and Characterization of Stable Suspensions of Ni Nanoparticles: Eun-Hee Lee, Min-Ku Lee, Chang-Kyu Rhee; J Korean Powder Metall Inst. 2006;13(2):138-143.; DOI: https://doi.org/10.4150/KPMI.2006.13.2.138

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In this study, the effects of the dispersants, i.e., Hypermer KD-2 and poly(l-vinyl-2-pyrrolidone) (PVP), and their concentration on the dispersion stability of Ni nanoparticles (10nmsim40nm) in ethanol were investigated by using a visual inspection, a transmission profile (Turbiscan), and a zeta potential measurement. The transmission profiles measured by Turbiscan showed that the particle size increased over the entire height of the sample for suspensions with both the dispersants without showing any particle coalescence and sedimentation. The visual inspection also confirmed that the Ni suspensions with Hypermer KD-2 and PVP were very stable for more than a year. The zeta potential values varied from positive to negative with increasing the dispersant's concentration. The dispersion stability of the suspensions was not affected by both the dispersant's concentration and the zeta potential values. The observed suspension stability of Ni nanoparticles was attributed to the steric effect for the Hypermer KD-2 and to the bridging effect for the PVP.

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Electrophoretic deposition of Ni nanoparticles from suspension on to a Ni plate
Keun-Yong Park, Young Rang Uhm, Kwang Jae Son, Deok-Yong Park
Research on Chemical Intermediates.2015; 41(9): 6721. CrossRef

[Korean]
Fabrication of Titanium Composites Containing nano-sized TiNx: Mun-Hyup Kim, Dong-Sik Kim, Young-Hwan Oh, Sung-Bum Park, Seung-Sik Park, Jee-Hye Lee, No-Jin Park, Sung-Jin Kim, Chan-Hoi Jung, Jun-Hee Lee; J Korean Powder Metall Inst. 2006;13(2):144-149.; DOI: https://doi.org/10.4150/KPMI.2006.13.2.144

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Abstract PDF: In this research we tried to make nano-sized TiNx by using planetary milling, and we made the composites double layered of titanium and nano-sized TiNx by using spark plasma sintering apparatus after mixing with the different ratio of pure titanium powder, and they were heat treated at 850°C for 30 minutes. The crystal structures of nano-sized TiNx powders and the composites were analyzed by X-ray diffraction (XRD). The microstructures of the powders were analyzed by using scanning electron microscopy (FESEM) and the 40-50 nm size of nano-sized TiNx particle on the surface of agglomerated particles was investigated. With increasing the ratio of nano-sized TiNx of the composites, the microvickers hardness of the composites was increased.

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