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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Analytical Science and Technology
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Journal DOI :
The Korean Society of Analytical Science
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Volume & Issues
Volume 6, Issue 5 - 00 1993
Volume 6, Issue 4 - 00 1993
Volume 6, Issue 3 - 00 1993
Volume 6, Issue 2 - 00 1993
Volume 6, Issue 1 - 00 1993
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Formation of the Fullerene-type Graphite Spherulites in the Ni-C Liquid under High Pressure
Park, Jong-Ku ;
Analytical Science and Technology, volume 6, issue 2, 1993, Pages 149~156
The formation of the graphite spherulites has been studied experimentally in the Ni-C liquid under high pressure and temperature. In the diamond-stable region the graphite spherulites were formed and grew stably. They were not the polycrystalline particles but the single crystals of the fullerene-type, respectively, grown spirally with much imperfection. And they were proved to be in a mixture state of carbon atoms with
-bonding by an Auger electron spectroscope and a high resolution transmission electron microscope. As the pressure decreased from the diamond-stable region to the graphite-stable region, the shape of the graphite particles changed gradually from the sphere to the flaky shape. The formation of the graphite spherulites was attributed to the stable existence of the carbon atoms with
bonding in the diamond-stable region. The formation of the large fullerene-type graphite spherulites with much imperfection is well agreed with Kroto's prediction for growth of the giant fullerene.
Analysis of the grain boundary precipitates in stainless steel by potentiostatic etching dissolution method
Park, Shin Hwa ; An, Byug Ryang ; Hong, Ki Jung ; Lee, Do Hyung ;
Analytical Science and Technology, volume 6, issue 2, 1993, Pages 157~165
The potentiostatic etching dissolution method, which had been used for the quantification of precipitates in steel, was applied to investigate the origin of cracks occurred in 304 stainless steel during processing. The morphology of crack propagation was observed by SEM. EDS and EPMA were used for the analysis of chemical composition of large precipitates on the grain boundary. The crystal structure of these large precipitates was determined by X-ray diffraction and electron diffraction. In both a stainless steel plate and a wire, the crack propagated along the grain boundary. Large precipitates on the grain boundary were identified to be
. Potentiostatic etching dissolution method was found to be appropriate to the sample preparation for the analysis of precipitates in stainless steel.
A Study on the Formation of Aluminide Coating on KM 1557 Alloy by Pack Cementation Process
Yoon, Jin-Kook ; Yoo, Myoung Ki ; Choi, Ju ; Kim, Jae-Soo ;
Analytical Science and Technology, volume 6, issue 2, 1993, Pages 167~180
The effects of coating variables on the formation of aluminide coating layer with good oxidation resistance on the strongest hot-forged superalloy in the world, KM 1557 developed at KIST by pack cementation process were studied. Pack aluminizing were performed by high-activity process with pure aluminium powders and by low-activity process with codep powders. For high-activity process, Al deposition rate, growth rate of coating layer, and cross-sectional microstructures were influenced by the species and additive amounts of activators and the additive amounts of pure aluminium powders. For low-activity process, Al deposition rate, growth rate of coating layer, and the cross-sectional microstructures were not influenced by the species but additive amounts of activators. Surface structures of coating layer were influenced by the species of activators. Regardless of aluminium activity, Al deposition rate was proportional to the square root of time and parabolic rate constants were different with the species of activators. The activation energy for deposition of aluminium was different with the species of activators for high-activity process. Regardless of the species of activators, the activation energy for deposition of aluminium was 12~14 Kcal/mole for low-activity process.
Microstructure and Mechanical Properties of SUS Alloy for Wear Resistant Materials
Cho, Kwon Koo ; Kim, Bo Su ; Ahn, In Shup ; Hur, Bo Young ; Yang, Sung Chul ; Kim, Hae Shup ;
Analytical Science and Technology, volume 6, issue 2, 1993, Pages 181~195
The purpose of this research is to improve the density and the hardness of the SUS alloys for wear resistant materials. The dependence of the density, shrinkage ratio and hardness of various alloys on the sintering temperature and composition were examined. Alloys added with 3% Ti shows the most proper sintering properties of shrinkage ratio and the hardness which is enough to substitute for existing high price materials.
Discussion on the Mechanical Alloying Process of Ni-20Cr alloy
Yoo, Myoung Ki ; Choi, Ju ;
Analytical Science and Technology, volume 6, issue 2, 1993, Pages 197~205
Blends of elemental Ni and 20 weight % Cr powder were milled for different period in a laboratory attritor. Powder size distribution, microstructure and X-ray diffraction characteristics were investigated as a function of processing period. Saturated magnetization, Ms and coercive force, Hc we also measured and compared with plasma melted ingot to confirm the mechanically alloyed states. Mechanical alloying occurred as a consequence of the partition of powders and the increase of interfacial area driving diffusing of Cr into Ni. However, magnetic properties of chemically homogeneous solid solution like melted ingot has not been observed even though steady state of submicron grain size has been achieved after milling over 15 hrs. Further mechanical alloying period gave refinement of grain size, which resulted in the increase of alloyed layer. It is concluded that homogenization should be controlled by the increase of interfacial area between constitutive powders caused by plastic particle deformation and by the diffusion of Cr within the alloyed phase into Ni-rich phase through lattice defects.
Effect of Mixing Method of Sintering Additives on the Sintered and Mechanical Properties of
Kim, Ji-Soon ;
Analytical Science and Technology, volume 6, issue 2, 1993, Pages 207~215
powders were mixed with sintering additives(
, YAG) by coprecipitation method. Mixing homogeneity, sintered and mechanical properties of coprecipitation-mixed powder compacts were compared with those of mechanically-mixed ones. SIMS-analysis for composition on the surface and in the matrix of prepared powder mixtures showed that the added YAG exists mainly on the
powder surfaces in a form of coating. From this result it could be concluded that coprecipitation method is superior to mechanical mixing in the mixing homogeneity. This mixing homogeneity can accompany an improvement in sintered density, microstructure and consequently the mechanical properties of sintered bodys.
AES Analysis of Au, Au/Cr, Au/Ni/Cr and Au/Pd/Cr Thin Films by the Change of Substrate Temperature and Annealing Temperature
Yoo, Kwang Soo ; Jung, Hyung Jin ;
Analytical Science and Technology, volume 6, issue 2, 1993, Pages 217~223
Thin films of the Au/Cr, Au/Ni/Cr and Au/Pd/Cr systems were deposited on alumina substrates at ambient temperature and
in a high-vacuum resistance heating evaporator and annealed at
for 1 hour in air, respectively. The film thicknesses of Au, Ni(or pd), and Cr were
, respectively. The substrate temperature during deposition and the post-deposition annealing temperature affected the sheet resistance of thin-films due to the inter-diffusion of each layer. As a result of Auger depth profile analysis, in the Au/Cr system Cr already diffused out to Au surface during deposition at the substrate temperature of
and Au distribution changed after heat treatment. In the Au/Ni/Cr and Au/Pd/Cr systems, diffusion phenomena of Ni and Pd were found and especially Ni (approximately 45 at.%) diffused out to Au surface and oxidized.
Preparation of Sintered ATZ by Sol-Gel Process and Properties
Han, Kyoung Ran ; Park, Sun Jin ; Hong, Kug-Sun ; Jun, Hyung Woo ;
Analytical Science and Technology, volume 6, issue 2, 1993, Pages 225~229
ATZ was prepared by adding an alumina sol equivalent to 2wt% as
to an aqueous slurry of alumina (AKP-30) and zirconia (TZ-2Y or TZ-0Y) in the range of 10-30ATZ, followed by gelation, calcination, and sintereing between
for 2h. They showed excellent microstructure with alumina grains of <
and>99% of the theoretical density. Fracture toughness of
was observed around 20ATZ which was higher than
obtainable by ball-milling.
Pyrolysis Behavior of Acrylic Binder/Piezoelectric Ceramic System for Multilayer Actuator
Park, Soung-Uy ; Lee, Jeon-Kook ; Jung, Hyung-Jin ;
Analytical Science and Technology, volume 6, issue 2, 1993, Pages 231~238
The thermal behavior of binder in multi-layer actuator has an effect on the properties of actuator. Binder burn-out process and thermal degradation mechanism of PNN-PZT/Acrylic binder were analyzed by FTIR, DSC, TGA. Binder was burnt out by two step. In oxygen atomsphere, thermal degradation was activated and final residue was minimized to 5%.
The Characterization of Structural and Optical Properties for rf Magnetron Sputtered
Kim, Tae-Song ; Oh, Myung-Hwan ; Kim, Chong-Hee ;
Analytical Science and Technology, volume 6, issue 2, 1993, Pages 239~246
The structure of
thin film deposited on ITO coated glass, bare glass and (100) Si substrates was not changed, but the crystallinity was improved by the polycrystalline ITO layer and (100) Si substrate. The composition of
thin film deposited on ITO coated glass was nearly stoichiometric ((Ba+Sr)/Ti=1.08~1.09) and very uniform through all deposition process. But as the deposition temperature increases, the interdiffusion between grown thin film and ITO layer and between ITO layer and base glass is severer.
thin film deposited on ITO coated glass substrate was highly transparent. The refractive index(
thin film deposited on ITO coated glass was 2.138~2.286 as a function of substrate temperature.