• Analytical Science and Technology
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• v.11 no.4
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• pp.316-320
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• 1998

An image analysis was used for the interpretation of microstructures of ferrous metal artifacts. For the purposes, various microstructural features such as average grain size, phase area, shape factor, and composition of the inclusions, were parameterized for the information about manufacturing techniques such as casting, heating and tempering. The carbon content was determined through the evaluation of the amount of pearlite phase. As the amount of pearlite phase increased the shape factor also increased. Grain size was relatively smaller in trans-section than in cross-section. The manufacturing direction was trans-sectional because the orientation of inclusions was elongated lengthwise. All inclusions was of silicate groups and the manufacturing temperature was estimated up to $1450^{\circ}C$.

• Journal of Powder Materials
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• v.9 no.5
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• pp.322-328
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• 2002

Fe-Co nanocomposite powders with different composition were prepared by chemical vapor condensation (CVC) process and their characterizations were studied by means of X-ray diffraction, transmission electron microscopy, and vibrating sample magnetometer. The particles having the mean size of 5~25 nm consisted of metallic cores and oxide shells. The Co contents and particle size increased with increasing the carrier gas flow rate of Co precursor. The saturation magnetization and coercivity increased with increasing Co content. and the saturation magnetization maximized at the 40 wt.%Co. The Fe-Co nanocomposite powder oxidized at $400^{\circ}C$ showed the maximum coercivity of 1739 Oe.

• Journal of Powder Materials
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• v.18 no.2
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• pp.181-187
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• 2011

PVDF was used as a polymeric matrix material in this work. Nickel powders with average particles size of 200 nm or 72 nm were used as fillers. PVDF/metal submicro- and nanocomposites were prepared by means of a mixing in twin screw extruder and planetary ball mill, respectively. All samples were prepared by hot pressing method. Their electrical, thermal and morphological properties were examined by dielectric spectroscopy, DSC, FTIR, XRD, optical microscopy and scanning electron microscopy. It was found that all properties of composites were strongly modified depending on the content of metal powders and filler particles size. Particularly, specific volume resistivity of PVDF/Ni composite with 0.2 wt.% of Ni was increased by factor of 1.5~4.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.18 no.10
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• pp.929-935
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• 2005

In this paper, synthetic conditions of titania nanparticle was investigated to enhance its uniformity of the particle size as a child particle on organic mother particle of liquid powder type electronic paper. The physical properties are very important to improve the uniformity of electrical charging properties Concentration of titania raw material ($C_9H_{19}NO_4Ti$) in the ethanol solvent, pH, and concentration of the solution in the D.I. water were selected as parameters. As a result, ultrafine and well crystallized titania nanoparticle with good uniformity could be synthesized as the concentration of the $C_9H_{19}NO_4Ti$ in the ethanol solvent, pH of the solution, and the amount of the D.I. water were increased. Using the optimized conditions, the titania nanparoticle with uniformly ultrafime size of 10 nm could be synthesized.

• Bulletin of the Korean Chemical Society
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• v.29 no.10
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• pp.2005-2008
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• 2008

A cyclotetraphosphazene derivative with eight chains was synthesized from octachlorocyclotetraphosphazene. The vesicles were prepared using the cyclotetraphosphazene derivative and cholesterol. The resulting vesicles were characterized by TEM and measurements of their encapsulation efficiency. The stability of the vesicles was enhanced with the addition of dihexadecylphosphate. The size and the encapsulation efficiency of the vesicles changed according to the amount of cholesterol added. The size and the encapsulation efficiency of the vesicle were lowest when the mole ratio (cholesterol: the cyclophosphazene derivative) was 0.9.

• Korean Journal of Materials Research
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• v.13 no.5
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• pp.285-291
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• 2003

The nanosized silver and gold particles are prepared by ERC method in which metal vapors with high temperature is rapidly quenched by coolants such as liquid nitrogen or liquid argon. In order to monitor the crystal structural changes on the internal and the surface of the nanosized noble metal particles, lattice parameter, internal strain and Debye-Waller factor are investigated, and the calculation of X-ray diffraction scattering intensity is performed. The lattice parameters of silver and gold particles agree with those of bulk materials, and crystal internal strain of the metal particles is not changed by rapid cooling. The Debye-Waller factor of gold particles is increased with decreasing particle size because of the surface softening phenomenon of nanosized particles, but the crystal structural change on the surface of the particles is not detected from the comparison the calculated X-ray diffraction profile with the experimental profile on gold particles with the particle size of 4 nm.

• The Korean Journal of Ceramics
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• v.7 no.2
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• pp.80-84
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• 2001

The anisotropic CdS platelets were synthesized in the lamellar bilayer phase region of the octylamine-water binary system. The influence of the synthesis conditions of the system components on morphology and size of the platelets was examined. Atomic force microscopy (AFM) and high-resolution transmission electron microscopy (HRTEM) studies have shown thickness and face size of the synthesized particles. Platelets with face sizes ranging from 50 to 250 nm and thickness from 10 to 30 nm have been synthesized at room temperature. In addition, HRTEM micrographs show that the synthesized platelets are poly crystal.

• Journal of the Korean Ceramic Society
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• v.32 no.1
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• pp.37-44
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• 1995

TiO2 fine powders were synthesized using oxygenolysis and hydrolysis reaction of TiCl4 vapor in gas phase. The TiO2 powder synthesized showed morphological differences depending on reaction system as follows: TiCl4-O2 reaction system produced the monosized particles having polyhedral shape with well-defined crystal planes and the particles did not agglomerate into secondary particles. TiCl4-H2O reaction system, whereas, produced the spherical secondary particles which consisted of fine primary particles. Other powder characteristics such as particle size, impurity content and rutile content are also reported in this study.

• Journal of the Korean Ceramic Society
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• v.32 no.1
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• pp.113-119
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• 1995

The green body was fabricated by a new forming method, pressureless powder packaing forming method, and the characteristics of sintered specimen were investigated. It was found that alumina ceramics prepared by the present method showed porous structure with narrow pore size distribution, and in case of abrasive powder sintered body, compared with dry-pressed specimen, had the nearly same density. Especially, the specimen prepared with spray-dried granules showed the characteristic that granules were not either deformed or fractured during forming and sintering process. Therefore, it was found that this new forming method was effective method in fabrication of porous ceramics on account of easy control of porosity and pore size and its high thermal stability.

• Carbon letters
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• v.10 no.4
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• pp.339-344
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• 2009

Henequen fiber was air-stabilized, carbonized, and steam-activated to obtain high surface area activated henequen fiber (AHF). Thermal behavior of henequen fibers has been studied by TGA. The structural morphology and characteristics were observed by SEM and BET surface area measurement. The yield of AHF from natural henequen was in the range of 20~25 wt%. Mesopores (2~2.5 nm) were developed on the AHF as the activation temperature was raised up to $700^{\circ}C$, and the band of mesopore size distribution moved to 15~30 nm when the activation were carried out at $900^{\circ}C$ for 30 min. The specific surface area and the total pore volume were about $1394\;m^2/g$ and $1.30\;cm^3/g$, respectively at this activation conditions.