• Proceedings of the Korean Magnestics Society Conference
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• 1999.10a
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• pp.58-59
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• 1999

• Proceedings of the Korean Magnestics Society Conference
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• 1999.10a
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• pp.56-57
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• 1999

• Journal of Powder Materials
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• v.1 no.1
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• pp.60-65
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• 1994

When a commercial prealloyed Fe-powder(Fe-5Cr-lMo-2Cu-0.5P-3C) is liquid phase sintered at 116$0^{\circ}C$, liquid precipitates with various shapes form within solid grains during the initial stage of sintering. The shape of a liquid precipitate changes pith the increment of their size from sphere(with radius<0.3$\mu\textrm{m}$), a transient polyhedron with more than 7 faces(1~2 $\mu\textrm{m}$), cuboid(3~5 $\mu\textrm{m}$), and finally to sphere(>5 $\mu\textrm{m}$). The shapes of liquid precipitates closely resemble the growth shapes predicted on the basis of solid-liquid interfacial energy and the coherency strain energy with anisotropic elastic constants in the diffusion zone around the precipitates.

• Journal of the Korean Society of Safety
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• v.3 no.1
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• pp.7-13
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• 1988

The oxides in perovskite type, $LaMO_3$ (M=Ni, Cr, Fe, Co), compared with gas sensors which have been used, were synthesised and then examined sensor response comparatively in order to make a thick film gas sensor having a good gas selectivity, durability and simple manufacturing. The oxides in perovskite type, $LaFe_{1-x}O_3$ (x=0.2, 0.4, 0.6, 0.8), which a part of Fe was replaced with Co, were examined with regard to their electric resistance with variable temperature and sensor response for carbon monoxide gas.

• Archives of Metallurgy and Materials
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• v.64 no.2
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• pp.539-542
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• 2019

Pre-alloyed Astaloy CrL^TM (Fe-1.5 wt% Cr-0.2 wt% Mo), a commercial Fe-based alloy powder for high strength powder metallurgy products, was sintered and hot forged with additions of 0.5 wt% C and 0~2 wt% Cu. To investigate the influence of various Cu contents, the microstructural evolution was characterized using density measurements, scanning electron microscope (SEM) and electron backscatter diffraction (EBSD). Transverse rupture strength (TRS) was measured for each composition and processing stage. The correlation between Cu additions and properties of sinter-forged Fe-Cr-Mo-C alloy was discussed in detail.

• Korean Chemical Engineering Research
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• v.53 no.3
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• pp.391-396
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• 2015

To investigate the effect of the catalyst synthesis method on the oxidative dehydrogenation (ODH) of nbutenes, $BiFe_{0.65}MoP_{0.1}$ oxide catalysts were prepared with various synthesis methods such as co-precipitation, citric acid method, hydrothermal method, and surfactant templated method. The catalysts were characterized by X-ray Diffraction (XRD), $N_2$ sorption, and $NH_3/1$-butene-temperature programmed desorption ($NH_3/1$-butene-TPD) to correlate with catalytic activity in ODH reaction. Among the catalysts studied here, $BiFe_{0.65}MoP_{0.1}$ oxide catalyst prepared with co-precipitation method marked the highest activity showing 1-butene conversion, 79.5%, butadiene selectivity, 85.1% and yield, 67.7% after reaction for 14 h. From the result of $NH_3$-TPD, the catalytic activity is closely related to the acidity of the $BiFe_{0.65}MoP_{0.1}$-x oxide catalyst and acidity of the $BiFe_{0.65}MoP_{0.1}$ oxde catalyst prepared with co-precipitation method was higher than that of other catalysts. In addition, combined with the 1-butene TPD, the higher catalytic activity is closely related to the amount of weakly adsorbed intermediate (< $200^{\circ}C$) and the desorbing temperature of strongly adsorbed intermediates (> $200^{\circ}C$).

• Journal of Powder Materials
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• v.23 no.5
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• pp.397-401
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• 2016

A lean alloy is defined as a low alloy steel with a minimum amount of the alloying element that maintains the characteristics of the sintered alloy. It is well known that the addition of elements such as Cr, P, Si, or Mn improves the mechanical characteristics of the alloy, but decreases the sinterability. The mother alloy is used to avoid an oxidation reaction with the alloying elements of Cr, P, Si or Mn. The purpose of this study is to determine the change in the mechanical properties of Fe-P-Mo and Fe-P-Mn alloys as a result of the addition of Si. In this article, the Fe-P-Mo and Fe-P-Mn alloys to which Si is added are compacted at $7.0g/cm^3$ and then sintered in $H_2-N_2$ at $1120^{\circ}C$. The P around the macropores and large grains reduces due to the formation of $SiO_2$ as the Si content increases. This is caused by the increase in strength owing to reducing intergranular fracture by suppressing the reaction with oxygen.

• Journal of the Korean Society for Heat Treatment
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• v.36 no.5
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• pp.303-310
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• 2023

β titanium alloys are widely used in aerospace industry due to their excellent specific strength and corrosion resistance. In particular, mechanical properties of metastable β titanium can efficiently be controlled by various deformation mechanisms such as slip, twinning, and SIM (Stress-Induced Martensite Transformation), making it an ideal material for many industrial applications. In this study, Ti-5Mo-xFe (x=1, 2, 4 wt%) alloy was designed by adding a relatively inexpensive β element to ensure price competitiveness. Additionally, microstructural analysis was conducted using OM, SEM, and XRD, while mechanical properties were evaluated through hardness and compression tests to consider the deformation mechanisms based on the Fe content. SIMT occurred in all three alloys and was influenced by the presence of β_m (metastable beta) and beta stability. As the Fe content decreased, the α'' phase increased due to SIMT occurring within the β_m phase, resulting in softening. Conversely, as the Fe content increased, the strength of the alloy increased due to a reduction in α'' formation and the contributions of solid solution strengthening and grain strengthening. Moreover, unlike the other alloys, shear bands were observed only in the fracture of the Ti-5Mo-4Fe alloy, which was attributed to differences in texture and microstructure.

• Journal of the Korean Magnetics Society
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• v.7 no.2
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• pp.90-96
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• 1997

We have studied crystallographic and magnetic properties of $NdFe_{10.7}Ti_ {1.2}Mo_{0.1}$ by Mossbauer spectroscopy, X-ray diffraction and vibrating sample magnetometer (VSM). The alloys were prepared by arc-melting under an argon atmosphere. The $NdFe_{10.7}Ti_{1.2}Mo_{0.1}$ has pure a single phase, whereas $NdFe_{10.7}Ti_{1.3}$ contains some $\alpha$-Fe, conformed with X-ray diffractometry and Mossbauer measurements. The $NdFe_{10.7}Ti_ {1.2}Mo_{0.1}$ has a $ThMn_{12}-type$ tetragonal structure with $a_0=8.637{\AA}$ and $c_0=4.807{\AA}$. The Curie temperature ($T_c$) is 600 K from the result of Mossbauer measurement performed at various temperatures ranging from 13 to 800 K. Each spectrum of below $T_c$ is fitted with five subspectra of Fe sites in the structure ($8i_1, 8i_2, 8j_2, 8j_1, 8f$). The area fractions of the subspectra at room temperature are 12.3%, 14.0%, 21.0% 11.8%, 40.9%, respectively. Magnetic hyperfine fields for the Fe sites decrease in the order, $H_{hf}(8i)>H_{hf}(8j)>H_{hf}(8f)$. The abrupt changes in the magnetic hyperfine field, an magnetic moment observed at about 160 K in $NdFe_ {10.7} Ti_{1.2}Mo_{0.1}$ are attributed to spin reorientations. The average hyperfine field of the $NdFe_{10.7}Ti_{1.2}Mo_{0.1}$ shows a temperature dependence of $[H_{hf}(T)-H_{hf}(0)]/H_{hf}(0)=-0.34(T/T_C)^{3/2}-0.14(T/T_C)^{5/2}$ for $T/T_c<0.7$, indicative of spin wave excitation. The Debye temperatures of $NdFe_{10.7}Ti_{1.2}Mo_{0.1}$ is found to be Θ=340$\pm$5 K.

• Journal of the Mineralogical Society of Korea
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• v.32 no.3
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• pp.223-234
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• 2019

The geology of the Samdeok Mo deposit consists of Paleozoic Hwajeonri formation, Kowoonri formation, Suchangri formation, Iwonri formation, Hwanggangri formation, Cretaceous, leucocratic porphyritic granite and granitic porphyry. This deposit consists of three quartz veins that filled NS oriented fractured zones in Suchangri formation. Quartz veins vary from 0.05 m to 0.3 m in thickness and extend to about 400 m in strike length. Quartz veins occur as massive, breccia, and cavity textures. Wallrock alteration has silicification, sericitization, argillitization and chloritization. The mineralogy of the quartz veins consists of quartz, fluorite, white mica, biotite, apatite, monazite, rutile, ilmenite, molybdenite, chalcopyrite, Fe-Mg-Mn oxide and Fe oxide. White mica from Samdeok Mo deposit occurs as fine or coarse grains in quartz vein and hostrock and has four mineral assemblages (I type: quartz, molybdenite, Fe oxide and Fe-Mg-Mn oxide, II type: quartz, Fe oxide and Fe-Mg-Mn oxide, III type: quartz and biotite, and IV type: quartz). The structural formular of white mica from quartz vein is $(K_{0.89-0.60}Na_{0.05-0.00}Ca_{0.01-0.00}Sr_{0.02-0.00})_{0.94-0.62}(Al_{1.54-1.12}Mg_{0.36-0.18}Fe_{0.26-0.09}Mn_{0.04-0.00}Ti_{0.02-0.00}Cr_{0.02-0.00}Zn_{0.01-0.00})_{1.91-1.72}(Si_{3.40-3.11}Al_{0.92-0.60})_{4.00}O_{10}(OH_{1.68-1.42}F_{0.58-0.32})_{2.00}$, but white mica of I type has higher FeO content, and lower $SiO_2$ and MgO contents than white micas of other types. Also, compositional variations in white mica from the Samdeok Mo deposit are caused by phengitic or Tschermark substitution ($(Al^{3+})^{VI}+(Al^{3+})^{IV}{\leftrightarrow}(Fe^{2+}{\text{ or }}Mg^{2+})^{VI}+(Si^{4+})^{IV}$) and direct $(Fe^{3+})^{VI}{\leftrightarrow}(Al^{3+})^{VI}$ substitution.