Journal of Powder Materials

Technology and Applications of Mechanical Alloying Processing: J Korean Powder Metall Inst. 2004;11(2):89-96.; DOI: https://doi.org/10.4150/KPMI.2004.11.2.089

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Equal Channel Angular Pressing of Rapidly Solidified Al-20 wt ％ Si Alloy Powder Extrudates: Seung-Chae Yoon, Soon-Jik Hong, Min-Hong Seo, Pham Quang, Hyoung-Seop Kim; J Korean Powder Metall Inst. 2004;11(2):97-104.; DOI: https://doi.org/10.4150/KPMI.2004.11.2.097

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In this paper processing and mechanical properties of Al-20 wt％ Si alloy was studied. A bulk form of Al-20Si alloy was prepared by gas atomizing powders having the powder size of 106-145 µm and powder extrusion. The powder extrudate was subsequently equal channel angular pressed up to 8 passes in order to refine grain and Si particle. The microstructure of the gas atomized powders, powder extrudates and equal channel angular pressed samples were investigated using a scanning electron microscope and X-ray diffraction. The mechanical properties of the bulk sample were measured by compressive tests and a micro Victors hardness test. Equal channel angular pressing was found to be effective in matrix grain and Si particle refinement, which enhanced the strength and hardness of the Al-2OSi alloy without deteriorating ductility in the range of experimental strain of 30％.

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Consolidation of Rapidly Solidified Al-20 wt％ Si Alloy Powders Using Equal Channel Angular Pressing

Journal of Korean Powder Metallurgy Institute.2004; 11(3): 233. CrossRef

A Study on the Nano Alloy Powders Synthesized by Simultaneous Pulsed Wire Evaporation (S-PWE) method II - Synthesis of Ee-Al Nano Alloy Powders: M. O., A. Yu.; J Korean Powder Metall Inst. 2004;11(2):105-110.; DOI: https://doi.org/10.4150/KPMI.2004.11.2.105

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In this study the possibility to obtain a homogeneous mixture and to produce solid solutions and intermetallic compounds of Fe and Al nano particles by simultaneous pulsed wire evaporation (S-PWE) have been investigated. The Fe and Al wires with 0.45 mm in diameter and 35 mm in length were continuously co-fed by a special mechanism to the explosion chamber and simultaneously exploded. The characteristics, e.g., phase composition, particle shape, and specific surface area of Fe-Al nano powders have been analyzed. The synthesized powders, beside for Al and alpha-Fe, contain significant amount of a high-temperature phase of gamma-Fe, Fe Al and traces of other intermetallics. The phase composition of powders could be changed over broad limits by varying initial explosion conditions, e.g. wire distance, input energy, for parallel wires of different metals. The yield of the nano powder is as large as 40 wt ％ and the powder may include up to 46 wt % FeAl as an intermetallic compound.

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Fabrication of Ni-free Fe-based Alloy Nano Powder by Pulsed Wire Evaporation in Liquid: Part I. Effect of Wire Diameter and Applied Voltage
Ho-Jin Ryu, Yong-Heui Lee, Kwang-Ug Son, Young-Min Kong, Jin-Chun Kim, Byoung-Kee Kim, Jung-Yeul Yun
Journal of Korean Powder Metallurgy Institute.2011; 18(2): 105. CrossRef
Fabrication of Ni-free Fe-based Alloy Nano Powder by Pulsed Wire Evaporation in Liquid: Part 2. Effect of Solvent and Comparison of Fabricated Powder owing to Fabrication Method
Ho-Jin Ryu, Yong-Heui Lee, Kwang-Ug Son, Young-Min Kong, Jin-Chun Kim, Byoung-Kee Kim, Jung-Yeul Yun
Journal of Korean Powder Metallurgy Institute.2011; 18(2): 112. CrossRef

Oxidation Behavior of WC-Co Hardmetal: J Korean Powder Metall Inst. 2004;11(2):111-117.; DOI: https://doi.org/10.4150/KPMI.2004.11.2.111

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The oxidation behavior of 91 WC-9Co hardmetal in weight percentage has been studied in the present work as a part of the development of recycling process. The morphological and compositional changes of the WC-Co hardmetal with oxidation time at 900°C were analyzed by using surface observation and X-ray diffraction. respective]y. As the oxidation time increased, the WC-Co hardmetal was continuously expanded to form porous oxide mixtures of CoWO_4 and WO_3. The morphology of porous oxide mixture was basically dependent on initial shape of the WC-Co hardmetal. From thermo-gravimetric (TG) analysis, it was found that the oxidation rate was increased with increasing oxidation temperature and oxygen content in the flowing atmospheric gas. The fraction of oxidation versus time curves showed S-curve relationship at a given of oxidation temperature. These oxidation behaviors of the WC-Co hardmetal were discussed in terms of previously proposed kinetic models.

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An Evaluation of WC-Co Tool Tip Scraps Reinforcement in the Hadfield Austenitic Manganese Steel Fabricated In Situ Steel Casting
Muhammad Rizki Gorbyandi Nadi, Gita Novian Hermana, Wiwik Purwadi, Cecep Ruskandi, Darma Firmansyah Undayat, Ari Siswanto
Metallography, Microstructure, and Analysis.2023; 12(5): 802. CrossRef
Fabrication of tungsten oxide powder from WC–Co cemented carbide scraps by oxidation behaviour
Min Soo Park, Jong-Min Gwak, Kyeong-mi Jang, Gook-Hyun Ha
Powder Metallurgy.2023; 66(5): 688. CrossRef
Influence of temperature on the biaxial strength of cemented carbides with different microstructures
E. Chicardi, R. Bermejo, F.J. Gotor, L. Llanes, Y. Torres
International Journal of Refractory Metals and Hard Materials.2018; 71: 82. CrossRef
Recovery of tungsten carbide from hard material sludge by oxidation and carbothermal reduction process
Woo-Gwang Jung
Journal of Industrial and Engineering Chemistry.2014; 20(4): 2384. CrossRef
Thermal oxidation behavior of WC–Co hard metal machining tool tip scraps
Wang-Hoi Gu, Yeon Seok Jeong, Kyeongmi Kim, Jin-Chun Kim, Seong-Ho Son, Sunjung Kim
Journal of Materials Processing Technology.2012; 212(6): 1250. CrossRef
Frictional wear evaluation of WC–Co alloy tool in friction stir spot welding of low carbon steel plates
D.H. Choi, C.Y. Lee, B.W. Ahn, J.H. Choi, Y.M. Yeon, K. Song, H.S. Park, Y.J. Kim, C.D. Yoo, S.B. Jung
International Journal of Refractory Metals and Hard Materials.2009; 27(6): 931. CrossRef

The Effect of pH and temperature on the Morphology of Aluminum Hydroxides formed by Hydrolysis Reaction: J Korean Powder Metall Inst. 2004;11(2):118-123.; DOI: https://doi.org/10.4150/KPMI.2004.11.2.118

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A formation of aluminum hydroxide by hydrolysis reaction in the water has been studied by using nano aluminum powder fabricated by pulsed wire evaporation(PWE) method. The hydroxide type and morphology depending on temperature and pH were examined by structural analysis. The Boehmite(Al_2O_3.H_2O or AIO(OH)) was predominantly formed in high temperature region over 40°C, while the Bayerite(Al_2O_3.H_2O or Al(OH)_3) below 30°C of hydrolysis temperature. The Boehmite formation was preferred to the Bayerite in acidic solution in the same hydrolysis temperature. The slowly formed Bayerite phase showed facet crystalline structure, while the fast formed Boehmite was fine fiber with a large aspect ratio of several nm in diameter and several hundred nm in length, and with much larger specific surface area(SSA) than that of Bayerite. The highest SSA was about 420m2/g.

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Tritium extraction in aluminum metal by heating method without melting
Ki Joon Kang, Jaehoon Byun, Hee Reyoung Kim
Nuclear Engineering and Technology.2022; 54(2): 469. CrossRef

Change of Particle Morphology and Ingredient Phase of WC and WC-Co Nanopowders Fabricated by Chemical Vapor Condensation during Subsequent Heat-Treatment: J Korean Powder Metall Inst. 2004;11(2):124-129.; DOI: https://doi.org/10.4150/KPMI.2004.11.2.124

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Abstract PDF: Nanosized WC and WC-Co powders were synthesised by chemical vapor condensation(CVC) process using the pyrolysis of tungsten hexacarbonyl(W(CO)_6) and cobalt octacarbonyl(Co_2(CO)_8). The microstructural changes and phase evolution of the CVC powders during post heat-treatment were studied using the XRD, FE-SEM, TEM, and ICP-MS. CVC powders were consisted of the loosely agglomerated sub-stoichimetric WC_1-x and the long-chain Co nanopowders. The sub-stochiometric CVC WC and WC-Co powders were carburized using the mixture gas of CH_4-H_2 in the temperature range of 730-850°C. Carbon content of CVC powder controlled by the gas phase carburization at 850°C was well matched with the theoretical carbon sioichiometry of WC, 6.13 wt％. During the gas phase carburization, the particle size of WC increased from 20 nm to 40 nm and the long chain structure of Co powders disappeared.

Phase Transformation by the Oxidation of Air-passivated W and Mo Nanopowders Produced by an Electrical Explosion of Wires: Young-Soon Kwon, Ji-Soon Kim, Alexander A. Gromov, Moon-Hee Hong; J Korean Powder Metall Inst. 2004;11(2):130-136.; DOI: https://doi.org/10.4150/KPMI.2004.11.2.130

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The passivation and oxidation process of tungsten and molybdenum narlopowders, produced by electrical explosion of wires was studied by means of FE-SEM, XPS. XRD, TEM, DIA-TGA and sire distribution analysis. In addition, the phase transformation of W and Mo nanopowders under oxidation in air was investigated. A chemical process is suggested for the oxidation of W and Mo nano-particles after a comprehensive testing of passivated and oxidized powders.

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Preparation of Mo nanopowders through hydrogen reduction of a combustion synthesized foam-like MoO2 precursor
Siyong Gu, Mingli Qin, Houan Zhang, Jidong Ma, Xuanhui Qu
International Journal of Refractory Metals and Hard Materials.2018; 76: 90. CrossRef

Chemical Solution Mixing and Hydrogen Reduction Method for Fabrication of Nanostructured Fe-Co Alloy Powders: J Korean Powder Metall Inst. 2004;11(2):137-142.; DOI: https://doi.org/10.4150/KPMI.2004.11.2.137

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Abstract PDF: In this study, chemical solution mixing and hydrogen reduction method was used to fabricate nanostructured Fe_xCo_1-x alloy powders. Fe-Co chloride mixture, FeCl_2 and COCI_2 with 99.9％ purity, were reduced in hydrogen atmosphere. Nanostructured Fe-Co alloy powders with a grain size of 50 nm were successfully fabricated. Magnetic properties of fabricated Fe_xCo_1-x(x=0, 10, 30, 50, 70, 100) alloy powders with the same grain size were measured because size factor can affect magnetic properties. Coercivity of Fe-Co alloy powders were increased with increasing Co contents. Maximum value of coercivity in various Co contented Fe-Co alloy powders with similar grain size was 125 Oe at Fe_100. Saturation magnetization value at Fe_70Co_30 composition showed maximum value of 219 emu/g and saturation magnetization value decreased with increasing Co contents and minimum value of 155 emu/g was observed at Co_100.

The Effects of Second Phases on the Photocatalytic Characteristics of the TiO₂ base Nano Composite: J Korean Powder Metall Inst. 2004;11(2):143-148.; DOI: https://doi.org/10.4150/KPMI.2004.11.2.143

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Abstract PDF: In the present study, TiO_2 imbedded composite powders have been successfully prepared from the (Cu. Zn)/TiO_2 composite salt solution. The composite (Cu, Zn)/TiO_2 powders were formed by drying the solution at 200~600°C in the hydrogen atmosphere. Photocatalytic characteristics was evaluated by detecting the decomposition ratio of aniline blue with UV-visible spectrophotometer(Shimazu Co., UV-1601). Phase analysis of (Cu, Zn)/TiO_2 composite powders was carried out by XRD and DSC, and powder size was measured with TEM. The mean particle size of composite powders was about 100mm. As the reduction temperature increases, a few zinc sulfide and oxide phases was formed and copper oxide phase was reduced. The decomposition ratio of aniline blue was about 80％ under the UV irradiation by the TiO_2 phase in the composite (Cu, Zn)/TiO_2 powders and similar decomposition ratio of 80％ was obtained at the UV lightless condition by virtue of Cu and Zn compounds.

Effect of the Ni Content and W Grain Size on the High Temperature Com-pressive Properties of W-Ni Activated Sintered Parts: J Korean Powder Metall Inst. 2004;11(2):149-157.; DOI: https://doi.org/10.4150/KPMI.2004.11.2.149

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Abstract PDF: High temperature deformation behavior of activated sintered W powder compacts was investigated. The compression tests were carried out in the temperature range between 900 and 1100°C at the strain rate of 10-3s-1. The sintered specimens of Ni-doped submicron W powder compacts showed decrease in W grain size with increasing the Ni content. As the result, the flow stress was significantly increased with increasing the Ni content. We obtained Ni-activated sintered W compacts with the relative density of 94 pm l％and the average grain size of less than 5µtextrmm. A moderate true strain up to 0.60 was obtained without fracture even at 1100°C with the strain rate of 10-3s-1 for the activated W compact despite adding the 1.0 wt％Ni to submicron W powder.

Fabrication and Characteristics of Continuous W-Cu FGM by SPS/Infiltration Process: J Korean Powder Metall Inst. 2004;11(2):158-164.; DOI: https://doi.org/10.4150/KPMI.2004.11.2.158

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Abstract PDF: W-Cu composite has been used for the applications requiring both high strength, good thermal and electrical conductivity. A graded combination of W and Cu will reduce thermal stress concerned with heat conduction, maintaining good thermal conductivity and high mechanical strength. In the present work, an attempt was made to fabricate continuous W-Cu FGM by preparing the graded porous structure of W skeleton using spark plasma sintering (SPS) process followed by infiltrating Cu. The graded porous structure was prepared at 1500°C for 60s under pressure of 15MPa by SPS process using a graphite mold with varying crr)ss section in the longitudinal direction. Infiltration of Cu was performed at 1150°C for 1 hour under H_2. W-Cu composite with graded Cu composition of 14 to 27 wt％ was finally prepared. In this process the gradient of composition could be conveniently controlled by varying the gradient of cross sectional area of graphite mold, temperature and pressure.

Growth Behavior of (Ti,W)(C,N) and WC grains in a Co Matrix: J Korean Powder Metall Inst. 2004;11(2):165-170.; DOI: https://doi.org/10.4150/KPMI.2004.11.2.165

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Abstract PDF: Growth behavior of two different types of grains, faceted and rounded, in a liquid matrix has been studied in the (75WC-25TiCN)-30Co system. Powder samples were sintered above the eutectic temperature for various times under a carbon saturated condition. (Ti,W)(C,N) grains with a rounded shape and WC grains with a faceted shape coexisted in the same Co based liquid. With increasing sintering time, the average size of (Ti.W)(C,N) grains increased continuously and very large WC grains appeared. The growth of rounded (Ti,W)(C,N) grains followed a cubic law, r3-r3_0=kt, where r is the average size of the grains, r_0 the initial average size, k the proportionality constant and t the sintering time. indicating a diffusion-controlled growth. On the other hand, the growth of the faceted WC grains resulted in a bimodal grain size distribution, showing an abnormal grain growth. These observations show that the growth behavior of different types of grains is governed by their shape, faceted or rounded, even in the same liquid matrix.

Study on the Sintering, Repressing and Mechanical Properties of Al₂O₃ and Al-Cu-SiC Composites: J Korean Powder Metall Inst. 2004;11(2):171-178.; DOI: https://doi.org/10.4150/KPMI.2004.11.2.171

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Abstract PDF: Effects of liquid phase and reinforcing particle morphology on the sintering of Al-6 wt％Cu-10 vol％ Al_2O_3 or SiC particles were studied in regards to densification, structure and transverse rupture properties. The Al-Cu liquid phase penetrated the boundaries between the aluminum matrix powders and the interfaces with reinforcing particles as well, indicating a good wettability to the powders. This enhanced the densification during sintering and the resulting strength and ductility. Since most of the copper added, however, was dissolved in the liquid phase and formed a brittle CuAl_2 phase upon cooling rather than alloyed with the aluminum matrix, the strengthening effect by the copper was not fully realized. Reinforcing particles of agglomerate type were found less suitable for the liquid phase sintering than solid type particles. Al_2O_3 and SiC particles protluced little difference on the sintering behavior but their size had a large effect. Repressing of the sintered composites increased density and bending properties but caused debonding at the matrix-particle interfaces and also fracturing of the particles.

Micro Metal Powder Injection Molding Technology: J Korean Powder Metall Inst. 2004;11(2):179-185.; DOI: https://doi.org/10.4150/KPMI.2004.11.2.179

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A study of the debinding and sintering behavior of T42 high-speed steel produced by powder injection molding (PIM)
Dong-Wook Park, Dae-Hwan Kim, Hye-Seong Kim, Youg-Sam Kwon, Kwon-Koo Cho, Su-Gun Lim, In-Shup Ahn
Research on Chemical Intermediates.2014; 40(7): 2415. CrossRef
A Study on the Sintering Behavior of T42 High Speed Steel by Powder Injection Molding (PIM) Process
Dong-Wook Park, Hye-Seong Kim, Young-Sam Kwon, Kwon-Koo Cho, Su-Gun Lim, In-Shup Ahn
Journal of Korean Powder Metallurgy Institute.2012; 19(2): 117. CrossRef

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