• Journal of Korea Foundry Society
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• v.29 no.6
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• pp.270-276
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• 2009

After casting button-type small ingots of ternary Fe-Mn-S alloys which had three different Mn/S ratios (1, 5 and 70) in a vacuum arc furnace, the effect of the ratio on the sulfide formation was investigated. In case of the Mn/S ratio of 1, if alloy composition was located in an iron-rich corner on a Fe-Mn-S ternary phase diagram, only duplex MnS-FeS sulfide films were observed in the grain boundary. If the alloy composition was located in the miscibility gap area of the phase diagram, primary globular dendritic sulfides and dendritic sulfide slags were generated within the grain and tubular monotectic sulfides were also detected in the grain boundary. When the Mn/S ratio was 5, if the alloy composition was in the iron-rich corner, only bead-like sulfides were generated. On the other hand, if the composition was in the miscibility gap area, globular dendritic sulfides and dendritic sulfide slags were generated in the form of primary sulfide inclusions and rod-like eutectic sulfides were observed in the grain boundary. Especially, if the contents of Mn and S increased more in the miscibility gap area of the phase diagram, primary globular sulfides containing iron intrusions were observed. In case of Mn/S ratio of 70, if the contents of Mn and S was decreased in the Fe corner of the phase diagram, only bead-like sulfides were observed in the grain boundary. Despite the composition was outside the miscibility gap area of the phase diagram, if the contents of Mn and S increased, clusters of fine sulfide particles as well as fine spherical primary monophase sulfides were observed in the grain boundary.

• Metals and materials international
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• v.24 no.6
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• pp.1333-1345
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• 2018

The effect of manganese sulfide (MnS) inclusions on the machinability of free-cutting steel is based on their morphology, size and distribution. Furthermore, the plasticity of MnS is high during the hot working caused different characterization of MnS. In this study, the deformation behavior of MnS in 1215MS steel after a thermomechanical process was investigated at 1323 K. The microstructures of MnS inclusions were characterized by optical microscopy, scanning electron microscopy, energy-dispersive spectrometry, and electron backscattering diffraction (EBSD). As the thickness reduction of the inclusions increased from 10 to 70%, their average aspect ratio increased from 1.20 to 2.39. In addition, the deformability of MnS inclusions was lower than that of the matrix. The possible slip systems of A, B, C, and D plane traces were (${\bar{1}}0{\bar{1}}$)[${\bar{1}}01$], ($10{\bar{1}}$)[101], (011)[$01{\bar{1}}$], and (110)[$1{\bar{1}}0$]. Furthermore, the EBSD measurements suggested that slip planes in MnS inclusions occur on {110} planes.

• Economic and Environmental Geology
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• v.18 no.2
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• pp.107-124
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• 1985

More than fifty copper veins are emplaced around late Cretaceous granitoid stock in Haman-Gunbuk district, southernmost part of Korea. These veins cut both late Cretaceous granitoids and hornfels of Jindong formation which is intruded by the granitoids. The paragenesis of veins is nearly the same, consisting of (1) an early vein stage in which most iron oxide minerals, tourmaline and other silitcate minerals were deposited, (2) a calcite and quartz with base·metal sulfide stage and (3) late vein lets of barren calcite stage. Fluid inclusion studies reveal highly systematic trends of salinity and temperature during mineralization. Ore fluids of early vein stage were complex NaCl-KCl rich brines. Salinities of polyphase inclusions in quartz and scapolite in thie stage reached up to 72 wt.% and gradually decreased to 10.5wt. % in closing stage. Homogenization temperatures of inclusions in the beginning of this stage were up to $490^{\circ}C$ and then declined steadly to $290^{\circ}C$ in the late stage. Salinities of fluid inclusions in quartz and calcite of base·metal sulfide stage were 37.4~5.7wt. % and homogenization temperatures range from $373^{\circ}C$ to $170^{\circ}C$. Intermittent boiling of early vein fluid is indicated by fluid inclusions in quartz. Potassic alteration of granodiorite adjacent to early vein seems to be related to early saline vein fluid. Fluid inclusion data of base-metal sulfide stage of this area reveal nearly the same range as those of Koseong copper mining district about 30km apart from this area.

• Journal of Korea Foundry Society
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• v.29 no.5
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• pp.220-224
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• 2009

In order to investigate the microstructural morphology of the sulfide expected from the Fe-FeS phase diagram, a vacuum-sealed quartz tube where pure iron (99.9%) and sulfur (99.99%) powders were charged was heated upto $1000^{\circ}C$ in the electric resistance furnace, held for 96 hours and quenched in cold water and then, rod specimen was produced. Compositional difference of the sulfur between upper and lower parts of the rod was 7.5wt.% and segregation of the sulfur was gradually increased from the lower part to the upper one of the rod. The rod specimen was divided into three parts by the microstructural morphology of the sulfide. The upper part of the rod specimen revealed single phase FeS intermetallic. In the middle part of the specimen, hyper-eutectic microstructure where primary FeS was precipitated first and then, eutectic of $\alpha$-Fe and FeS was formed in the inter-dendritic region of the FeS. Especially, hypo-eutectic microstructure was appeared in the lower part of the specimen. After primary dendrite of $\alpha$-Fe solidified, FeS dendrite which included small amount of $\alpha$-Fe and FeS eutectic in the inter-dendritic region was formed.

• Economic and Environmental Geology
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• v.25 no.3
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• pp.283-296
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• 1992

The Keumryeong deposits is a low grade copper deposits in which copper minerals form disseminated grains and thin veinlets in felsic volcanics seem to be dacite. Alteration of the volcanics consists mainly pervasive propylitization and silicification. Potassic alteration characterized by biotite developed locally adjacent to southwestern contact of granodiorite body. Principal sulfide minerals in altered zone are mainly pyrite and lesser chalcopyrite. Chalcopyrite content in potassic zone is relatively higher than that of surrounding propylitized zone. Pyrite and chalcopyrite accompanies magnetite, molybdenite, sphalerite, pyrrhotite, arsenopyrite, pentlandite, marcasite, hematite, ilmenite, rutile, bismuthinite and native Bi as disseminations, veinlets and knots. Granodiorite body is propylitized and contains veinlets of pyrite, chalcopyrite and molybdenite. Fluid inclusions in sulfide-bearing quartz veinlets and quartz grains of felsic volcanics and granodiorite in altered zone consist of liquid-rich, vapor-rich, $CO_2-bearing$ and halite-bearing inclusions. These four types of inclusion intimately associated on a microscopic scale and indicate condensing or boiling of ore fluid during mineralization. Homogenization temperature of coexisting fluid inclusions are mostly in the range of 350 to $450^{\circ}C$. High salinity fluid contains 28.6 to 48.4 weight percent NaCI equivalent and moderate salinity fluid cotains 0.5 to 12.5 weight percent NaCl equivalent. Pressure estimated from $CO_2$ mole fraction of $CO_2-bearing$ inclusion range 160 to 375 bars. The Kigu copper deposits is a fissure filling copper vein developed 500 m south from the Keumryong deposits. Mineralogy and fluid inclusion data of the Kigu deposits are similar to that of the Keumryeong deposits. Homogenization temperature of fluid inclusions from the Kigu deposits are reasonable agreement with temperature estimated from sulfidation curve of cubanite-chalcopyrite-pyrite-pyrrhotite and pyrite-pyrrhotite mineral assemblages. Not only mineral occurrence and wall rock alteration in the Keumryeong deposits but also fluid inclusion data such as temperature, salinity, pressure and boiling evidences are similar to those of porphyry copper deposits.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.7 no.1
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• pp.75-81
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• 1998

We have studied internal quality including chemical compositions, microscopic structure and nonmetallic inclusion of test materials. We have analyzed tensile strength value, hardness value, impact value etc. In analyzing internal quality, all of the test materials showed typical ferrite+pearlite structure. But nonmetallic inclusion showed oxide and sulfide inclusions in medium carbon steels, and sulfide inclusion is S-free cutting steels. In ca+ S-free cutting steels, the calcium aluminate and sulfide complex inclusion had low-melting points as deformation of sulfide and oxide inclusion is existed. It was found that tensile strength and hardness give maximum value in medium carbon steels, where as minimum in Ca + -free cutting steels. But values of elongation, reduction of area impact are reverse. Fracture surface of impact specimen is ductile in free cutting steels but brittle in medium cabon steels.

• Economic and Environmental Geology
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• v.15 no.1
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• pp.1-16
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• 1982

Many skarn type iron ore deposits are distributed in Kimhae-Mulgeum area of Gyeongnam Province. Integrated field, mineralogic, geochemical and fluid inclusion studies were undertaken to illustrate the character and origin of the ores in this area. The iron ore deposits in this area are NS or NNE trending fracture filling magnetite veins which are developed in andesitic rocks near the contact with late Cretaceous micrographic granite bodies. Symmetrically zoned skarns are commonly developed in the magnetite veins of this area. Zoning of skarn from center to margin of the vein are as follows; garnet quartz skarn-epidote skarn-epidote orthoclase skarn-altered andesitic rocks. Major ore mineral is magnetite and small amount of hematite, pyrite, pyrrhotite, chalcopyrite and sphalerite are associated. Vein paragenesis reveals four depositional stages; 1) skarn stage, 2) iron sulfide and oxide stage, 3) skarn stage, 4) sulfide stage Minute halite-bearing polyphase inclusions and liquid inclusions are contained in quartz. Filling temperatures range from $257^{\circ}$ to $370^{\circ}C$.

• Corrosion Science and Technology
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• v.19 no.3
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• pp.122-130
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• 2020

In this study, a corrosion failure analysis of a heat transport pipe was conducted, as the result of a pinhole leak. Interestingly, the corrosion damage occurred externally in the pipeline, resulting in severe thickness reduction near the seam line. Also, while a stable magnetite protective film formed on the inner surface, the manganese oxide formation occurred only on the outer surface. The interior and exterior of the pipe were composed of ferrite and pearlite. The large manganese sulfide and alumina inclusions were found near the seam line. In addition, the manganese sulfide inclusions resulted in grooving corrosion, which progressed in the seam line leading to the reduction in the thickness, followed by the exposure of the alumina in the matrix to the outer surface. To note, the corrosion was accelerated by pits generated from the boundaries separating the inclusions from the matrix, which resulted in pinhole leaks and water loss.

• The Journal of the Petrological Society of Korea
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• v.13 no.1
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• pp.34-45
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• 2004

This paper describes the textural relations of mantle xenoliths and fluid inclusions in mantle-derived rocks found in alkaline basalts from Jeju Island which contain abundant ultramafic, felsic, and cumulate xenoliths. Most of the ultramafic xenoliths are spinel-lherzolites, composed of olivine, orthopyroxene, clinopyroxene and spinel. The felsic xenoliths considered as partially molten buchites consist of quartz and plagioclase with black veinlets, which are the product of ultrahigh-temperature metamorphism of lower crustal materials. The cumulate xenoliths, clinopyroxene-rich or clinopyroxene megacrysts, are also present. Textural examination of these xenoliths reveals that the xenoliths are typically coarse grained with metamorphic characteristics, testifying to a complex history of evolution of the lower crust/upper mantle source region. The ultramafic xenoliths contain protogranular, porphyroclastic and equigranular textures with annealing features, indicating the presence of shear regime in upper mantle of the Island. The preferential associations of spinel and olivine with large orthopyroxenes suggest a previous high temperature equilibrium in the high-Al field and the original rock-type was a Al-rich orthopyroxene-bearing peridotite without garnet. Three types of fluid inclusions trapped in mantle-derived xenoliths include CO$_2$-rich fluid (Type I), multiphase silicate melt (glass ${\pm}$ devitrified crystals ${\pm}$ one or more daughter crystals ＋ one or more vapor bubbles) (Type II), and sulfide (melt) inclusions (Type III). C$_2$-rich inclusions are the most abundant volatile species in mantle xenoliths, supporting the presence of a separate CO$_2$-rich phase. These CO$_2$-rich inclusions are spatially associated with silicate and sulfide melts, suggesting immiscibility between them. Most multiphase silicate melt inclusions contain considerable amount of silicic glass. reflecting the formation of silicic melts in the lower crust/upper mantle. Combining fluid and melt inclusion data with conventional petrological and geochemical information will help to constrain the fluid regime, fluid-melt-mineral interaction processes in the mantle of the Korean Peninsula and pressure-temperature history of the host xenoliths in future studies.

• Economic and Environmental Geology
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• v.15 no.4
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• pp.221-233
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• 1982

Ssangjeon tungsten ore deposits is a complex pegmatite deposits embedded along the contact between pre-Cambrian Buncheon granite gneiss and amphibolite. This pegmatite vein developed 2 km along the strike and thickness varies from 10m to 40m. Mineral constituent of the normal pegmatite are quartz, microcline, plagioclase, muscovite, biotite, tourmaline and garnet. The vein paragenesis is complicated by repeated deposition of quartz but three distinct depositional stage can be recognized. Quartz A stage is the stage of the earliest milky white quartz deposition as a rock forming mineral of normal pegmatite. Quartz B stage is the stage of gray to dark gray quartz replace earlier formed normal pegmatite minerals. Quartz C stage is the stage of latest white translucent massive quartz replace quartz A and B. Tungsten ore minerals and other sulfide minerals were precipitated during quartz B stage. Ore minerals are ferberite and scheelite. Minor amount of molybdenite, arsenopyrite, pyrrhotite, pyrite, chalcopyrite, sphalerite, galena, pentlandite, bismuthinite, native bismuth and marcasite accompanied. Fluid inclusion in quartz A and B are gaseous inclusions and liquid inclusions are contained in quartz C as a primary inclusions. Salinity of inclusions in quartz A and B ranges from 4.5 to 9.5 wt. % and from 5.1 to 6.0 wt. % equivalent NaCl respectively. Homogenization temperature of quartz A; quartz B and quartz C ranges from 415 to $465^{\circ}C$, from 397 to $441^{\circ}C$ and from 278 to $357^{\circ}C$. $CO_2$ content of the ore fluid increased at the ends of quartz B stage.