• Journal of Surface Science and Engineering
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• v.35 no.4
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• pp.232-240
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• 2002

The composition and the microstructure of the Zn-Cr alloys electroplated in chloride bath with EDTA were studied according to electrolysis conditions. The cathode current efficiency decreased with increasing both Cr/(Cr+Zn) ratio and current density. The Cr content of the alloy deposits increased with Cr/(Cr+Zn) ratio and current density The phase structure of Zn-Cr alloy deposits changed from η-Zn through η-Zn+${\gamma}$'-ZnCr to ${\gamma}$'-ZnCr with increasing Cr content of alloys. The surface morphology of Zn-Cr alloy deposits changed from fine needle shaped crystallites through the mixed structure of needle-shaped and granular one to the colony structure with fine granular crystallites according to the change of phase structure

• Journal of Powder Materials
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• v.10 no.3
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• pp.157-160
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• 2003

Phase contents and elemental composition of ultradispersed powders obtained by the electrical explosion of tin-leadalloy powders are investigated. It is demonstrated that during the explosion and subsequent cooling, surface layers of powder particles are enriched in lead compared to the initial alloy. The thermal stability of powders oxidizing in air is also investigated.

• Journal of Powder Materials
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• v.19 no.3
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• pp.196-203
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• 2012

$TiO_2$ was successfully formed on a Ti specimen by MAO (Micro-Arc-Oxidation) method treated in $Na_3PO_4$ electrolyte. This study deals with the influence of voltage and working time on the change of surface microstructure and phase composition. Voltage affected the forming rate of the oxidized layer and surface microstructure where, a low voltage led to a high surface roughness, more holes and a thin oxidized layer. On the other hand, a high voltage led to more dense surface structure, wider surface holes, a thick layer and fewer holes. Higher voltage increases photocatalytic activity because of better crystallization of the oxidized layer and good phase composition with anatase and rutile $TiO_2$, which is able to effectively separate excited electrons and holes at the surface.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.15 no.7
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• pp.563-571
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• 2003

The forty vapor-liquid equilibrium data of the binary system, HFC125＋Propane, were measured between 273.15 and 313.15 K at 10 K interval and the composition range 0.2∼0.75, respectively. Experiments were performed in a circulation type apparatus in which the vapor phase was forced through the liquid phase. The composition at equilibrium were mea-sured by gas chromatography, and its response was calibrated using gravimetrically prepared mixtures. Vapor-liquid equilibrium data were calculated by using CSD equation of state and compared with the experimental data.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
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• v.9 no.1
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• pp.19-24
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• 2003

We study on the phase diagram of the polymer blend. For this purpose, one PS (polystyrene) and two PI(polyisoprene) were employed whose molecular weights were low enough to make the experimental determinations possible. The weight-average molecular weight(Mw) of PS was 2514, and Mws of two PIs were 2700. Interaction energy density (IED) of the Flory-Huggins lattice theory was defined as a function of temperature and composition, and the consequent equations for the binodal, and critical points were derived. By fitting the experimental binodal points to the derived binodal curve with a nonlinear regression method, the expression for the IED was determined. And the expression for the IED obtained from this study was compared with those reported in the literatures. Also were discussed the importance of accuracy in the expression the IED, and the IED's dependency on the temperature, composition and molecular weights.

• Journal of Surface Science and Engineering
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• v.32 no.3
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• pp.281-288
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• 1999

Electrodeposited Zn-Ni alloy coatings are of particular interest for improving the corrosion resistance of steel in a number of enviornments. Of particular interest is the relationship between composition, structure and corrosion rate. This paper firstly reviews the literature regarding composition-structure relationships of Zn-Ni electrodeposits and compares them with the equilibrium phase diagram. Secondly, research was carried out on a wide range of coatings which were produced in the laboratory and their structure and corrosion rates determined. It was found that unambiguous identification of phases from XRD data can be difficult. Maximum corrosion resistance of deposits is obtained at 12-13% Ni, with a $\gamma$ phase structure and predomination of (600) and (411) reflections. Compatibility is important with regard to chromate conversion coatings.

• Archives of Metallurgy and Materials
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• v.65 no.3
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• pp.1005-1009
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• 2020

In this study, a non-equiatomic high entropy alloy was fabricated using the spark plasma sintering method, and its microstructural features and mechanical properties were investigated. The chemical composition of FeMnCoCr was determined by using the entropy calculation related to the design of high entropy alloys. A bulk sample with the same composition was also prepared using the conventional metallurgical processes of casting and hot rolling. The microstructures of the samples fabricated by these different processes were compared by microscope observation, and a quantitative phase analysis was carried out using FE-SEM. Hardness measurement was used to evaluate mechanical properties. Particular attention was paid to microstructural changes due to heat treatment, which was analyzed by considering how austenite stability is affected by grain refinement.

• Journal of the Korean Ceramic Society
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• v.34 no.8
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• pp.886-896
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• 1997

To investigate an effect of phase separation on precipitation characteristics of CuCl nanocrystals in CuCl doped nonlinear optical glasses, borosilicate glass systems with 9 different compositions with ~2wt% of CuCl were selected and CuCl doped glasses were prepared by melting and precipitation method. Microstructural properties of the CuCl doped glasses were analyzed by optical absorption spectroscopy, acid elution test, TEM, and EDXS. While phase separation did not occur in Glass A~D, interconnected and droplet microstructures due to phase separation were found in Glass E, F and Glass G~I, respectively. In the particular composition of the matrix glasses in this study, the precipitation of the CuCl particles was observed in the phase separable glasses, not in phase non-separable glasses. The CuCl particles were precipitated in both silica-rich phase region and boronrich phase region of the glass matrix. In the case of 7.7Na2O-36.6B2O3-52.7SiO2(mole%) glass, the larger CuCl particles than those in the silica-rich phase region were observed in the boron-rich phase region.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.15 no.5
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• pp.455-459
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• 2002

I have investigated the effects of annealing on a polymeric $\alpha-C_3N_{4.2}$ at high pressure and temperature in the presence of seeds of crystalline carbon nitride films prepared by a high voltage discharge plasma. The samples were evaluated by x-ray photoelectron spectroscopy (XPS), infrared spectroscopy, Auger electron spectroscopy and x-ray diffraction(XRD). Notably, XPS studies of the film composition before and after annealing demonstrate that the nitrogen composition in $\alpha-C_3N_{4.2}$ material initially containing more than 58% nitrogen decreases during the annealing process and reaches a common, stable composition of ~43%. XPS analysis also shows that the nitrogen composition in the annealed films without polymeric $\alpha-C_3N_{4.2}$ was reduced from 35% to 17%. Furthermore the concentration of the sp$^3$bonded phase increased with the increment of the annealing temperature.

• Journal of the Korean Society for Heat Treatment
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• v.12 no.4
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• pp.320-326
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• 1999

In rapidly solidified $Al_{92-x}Nd_8$(Cu,Ag)x ($0{\leq}X{\leq}10at%$) alloys, amorphous single phases were obtained in the ranges of $Oat%{\leq}X{\leq}4at%$ for Al-Nd-Cu system and $Oat%{\leq}X{\leq}6at%$ for Al-Nd-Ag system, respectively. Mesoscopic structures consisted of amorphous and crystalline phases were formed above solute ranges. It was founded that the mesoscopic structures were also formed near 1st exothermic peak on DSC curve by aging in amorphous single phase alloys. For example, amorphous $Al_{92-x}Nd_8$(Cu,Ag)x (X=2.4at%) alloys containing nanoscale Al particles and compounds, i.e., mesoscopic structure, exhibited higher tensile fracture strength(${\sigma}_f$) than those of amorphous single phase alloys with the same composition. The ${\sigma}_f$ showed a maximum value in the $V_f$ ranges of 10~15%. The reason is presumed that the nanoscale precipitates which have higher mechanical strength compared with the amorphous phase with the same composition act as an effective resistance to shear deformation of the amorphous matrix.