Journal of Powder Materials

Jung-Ho Ahn

5 Articles

Structural Modification of Carbon Nanotubes during Ball-milling: Hye Rim Nam, Jung-Ho Ahn; J Powder Mater. 2013;20(4):258-263.; DOI: https://doi.org/10.4150/KPMI.2013.20.4.258

17 View
0 Download
2 Citations

We examined various ball-milling parameters which affect the structural and morphological modification of multi-wall carbon nanotubes. In particular, the effect of milling mode and the use of different milling agents were examined. Friction milling mode induced more structural changes than impact milling mode except the use of dry ice as a milling agent. Wet milling was helpful for reducing more effectively the agglomeration of nanotubes than dry milling. The use of hard solid particles such as silica and alumina as milling agents resulted in an effective shortening of nanotubes, but often susceptible to the amorphization and the destruction of crystallinity.

Citations

Citations to this article as recorded by

Development of a Hydrogen Uptake-Release Mg-Based Alloy by Adding a Polymer CMC (Carboxymethylcellulose, Sodium Salt) via Reaction-Accompanying Milling
Young Jun Kwak, Eunho Choi, Myoung Youp Song
Metals and Materials International.2018; 24(5): 1181. CrossRef
Expansion of Multi-wall Carbon Nanotubes and its Lithium Storage Property
Jung-Ho Ahn, Jeong-Seok Ahn
Journal of Korean Powder Metallurgy Institute.2017; 24(4): 275. CrossRef

Synthesis of Al/AlN Composites by Mechanical Alloying and the Effect of PCA on Their Properties: Seok-Hyeoun Kim, Yong-Jin Kim, Jung-Ho Ahn; J Korean Powder Metall Inst. 2011;18(3):238-243.; DOI: https://doi.org/10.4150/KPMI.2011.18.3.238

17 View
0 Download

Abstract PDF: Al/AlN composites were synthesized by mechanical alloying using process control agents(PCAs). Three different PCAs which contain N element, were examined to see the effectiveness of ball-milling and the nitridation during sintering. Among examined PCAs, C_8H_6N_4O_5 was the most effective to facilitate ball-milling and to form nitrides during a subsequent sintering. By a proper control of ball-milling and sintering, we could obtained surface-hardened Al-based composites.

Synthesis of Yttrium Oxide Nanowire by Hydrothermal Method: Kyung-Ki Kim, Yong-Jin Kim, Jung-Ho Ahn; J Korean Powder Metall Inst. 2011;18(1):73-77.; DOI: https://doi.org/10.4150/KPMI.2011.18.1.073

15 View
0 Download
1 Citations

Abstract PDF

Y(OH)_3 nanowires were synthesized by a hydrothermal reaction of metallic Y with aqueous solution of LiOH. The morphology and the size of the nanowires changed with varying the volume of the LiOH solution inside the autoclave. Y(OH)_3 nanowires transformed to Y_2O_3 by a subsequent heat-treatment without morphological change. By a proper control of hydrothermal reaction parameter and heat-treatment, the yield of pure Y_2O_3 nanowires up to 97% was attained.

Citations

Citations to this article as recorded by

Synthesis and Characterization of SnO2-CoO/carbon-coated CoO Core/shell Nanowire Composites
Yu-Jin Lee, Bon-Ryul Koo, Hyo-Jin Ahn
Journal of Korean Powder Metallurgy Institute.2014; 21(5): 360. CrossRef

Hydrogen Storage Properties of Carbon Nanotube Composites: Jung-Ho Ahn, Min-Kyu Jang; J Korean Powder Metall Inst. 2008;15(3):188-195.; DOI: https://doi.org/10.4150/KPMI.2008.15.3.188

17 View
0 Download

Abstract PDF: Carbon nanotube (CNT)/Mg_2Ni composites were synthesized to enhance the hydrogen storage properties. The emphasis was made on the effect of different shortening methods of CNTs on the open-tip structure and the resulting properties. The use of open CNTs as a starting material resulted in an enhanced hydrogen properties of CNT/Mg_2Ni composites. Among the employed methods for the shortening of CNTs, wet milling using ethanol was the most efficient, while ultrasonic acid treatment or thermal decomposition resulted in a less hydrogen storage capacity.

Synthesis of Carbon Nanotubes by Chemical Method at Warm Temperatures: Jung-Ho Ahn, Sang-Hyun Lee, Yong-Jin Kim, Byung-Sik Chung; J Korean Powder Metall Inst. 2006;13(5):305-312.; DOI: https://doi.org/10.4150/KPMI.2006.13.5.305

18 View
0 Download

Abstract PDF: Amorphous carbon nanotubes were synthesized by a reaction of benzene, ferrocene and Na mixture in a small autoclave at temperatures as low as 400°C. The resulting carbon nanotubes were short and straight, but their inner hole was filled with residual products. The addition of quartz to the reacting mixture considerably promoted the formation of carbon nanotubes. A careful examination of powder structure suggested that the nanotubes in this process were mainly formed by surface diffusion of carbon atoms at the surface of solid catalytic particles, not by VLS(vapor-liquid-solid) mechanism.

Author index