• Korean Journal of Materials Research
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• v.33 no.3
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• pp.106-114
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• 2023

The carbon concentration in the carburized steels was measured by electron probe microanalysis (EPMA) for a range of soluted carbon content in austenite from 0.1 to 1.2 wt%. This study demonstrates the problems in carbon quantitative analysis using the existing calibration curve derived from pure iron (0.008 wt%C) and graphite (99.98 wt%C) as standard specimens. In order to derive an improved calibration curve, carbon homogenization treatment was performed to produce a uniform Kα intensity in selected standard samples (AISI 8620, AISI 4140, AISI 1065, AISI 52100 steel). The trend of detection intensity was identified according to the analysis condition, such as accelerating voltage (10, 15, 30 keV), and beam current (20, 50 nA). The appropriate analysis conditions (15 keV, 20 nA) were derived. When the carbon concentration depth profile of the carburized specimen was measured for a short carburizing time using the improved calibration curve, it proved to be a more reliable and accurate analysis method compared to the conventional analysis method.

• Journal of the Mineralogical Society of Korea
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• v.15 no.2
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• pp.122-131
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• 2002

Muscovite, chlorite and biotite in metapelites of the Ogcheon Hetamorphic Belt are studied using electron probe microanalysis (EPMA), backscattered electron images (BEI) of scanning electron microscopy (SEM) and lattice fringe images of transmission electron microscopy (TEM). These minerals are observed to be intergrown under a polarized light microscope and are apparently interlayered below EPMA resolution; EPMA data often indicate mixtures of phyllosilicates such as muscovite/chlorite (M/C), biotite/chlorite (B/C), muscovite/pyrophyllite/chlorite (M/P/C). biotite/pyrophyllite/chlorite (B/P/C) or biotite/muscovite/chlorite (B/M/C). BEI observations show that the three minerals (muscovite, chlorite and biotite) are mixed at various scales in a grain through the garnet zone, and the interlayering of the three minerals are observed from TEM lattice fringe images and selected area electron diffraction patterns. The result of TEM observations reveals that 7-$\AA$ layers (serpentine, precursor of chlorite) are interlayered within 10-$\AA$ layers (muscovite) at 100~200 $\AA$ scale as well as M/C in the chlorite zone. The 7-$\AA$ layers become smaller in size and less frequent in the biotite tone, and 10-$\AA$ layers are interlayered with chlorite (14 $\AA$) at an individual layer scale. The 7-$\AA$ layers are no longer observed in the garnet zone, and 10-$\AA$ layers (biotite) are interlayered with chlorite (B/C) at 50~100 $\AA$ scale. Relatively large scale (1000~2000 $\AA$) of intergrowth is also frequently observed from the garnet zone samples. However, rocks from all three metamorphic zones show interlayering of a few units of 7-, 10- and 14-$\AA$ layers with each other at TEM observations. The result of this study implies that metamorphic minerals such as muscovite, chlorite and biotite form through disequilibrum mineral reactions resulting in inhomogenious phases.

• Journal of the Mineralogical Society of Korea
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• v.23 no.2
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• pp.125-139
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• 2010

Behavior of heavy metals and arsenic in the tailings of Songcheon Au-Ag mine was characterized via both mineralogical and geochemical methods. Mineral composition of the tailings was investigated by X-ray diffractometry, energy-dispersive spectroscopy, and electron probe micro-analyzer (EPMA) and total concentrations of heavy metals and arsenic and their chemical forms were analyzed by total digestion of aqua regia and sequential extraction method, respectively. The results of mineralogical study indicate that the tailings included mineral particles of resinous shape mainly consisting of galena, sphalerite, pyrite, quartz, and scorodite, and specifically socordite was identified in the form of matrix. EPMA quantitative analyses were performed to evaluate the weatherability of each mineral, and the results suggest that it decreased in the sequence of arsenopyrite > galena > sphalerite > pyrite. The weathering pattern of galena was observed to show distinctive zonal structure consisting of secondary minerals such as anglesite and beudantite. In addition, almost all of arsenopyrite has been altered to scorodite existing asmatrix and galena, sphalerite, and pyrite which have lower weatherability than arsenopyrite were identified within the matrix of scorodite. During the process of alteration of arsenopyrite into scorodite, it is likely that a portion of arsenic was lixiviated and caused a great deal of detrimental effects to surrounding environment. The results of EPMA quantitative analyses verify that the stability of scorodite was relatively high and this stable scorodite has restrained the weathering of other primary minerals within tailings as a result of its coating of mineral surfaces. For this reason, Songcheon tailings show the characteristics of the first weathering stage, although they have been exposed to the surface environment for a long time. Based on the overall results of mineralogical and geochemical studies undertaken in this research, if the tailings are kept to be exposed to the surface environment and the weathering process is continuous, not only hazardous heavy metals, such as lead and arsenic seem to be significantly leached out because their larger portions are being partitioned in weakly-bound (highly-mobile) fractions, but the potential of arsenic leaching is likely to be high as the stability of scorodite is gradually decreased. Consequently, it is speculated that the environmental hazard of Songcheon mine is significantly high.

• Journal of the Mineralogical Society of Korea
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• v.16 no.3
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• pp.233-243
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• 2003

Microstructures and chemistry of anorthoclase, a high-temperature phase of alkali feldspars, were studied using EPMA and TEM. BSE images of anorthoclase displayed mixtures of Na-rich areas and K-rich areas forming lamella of various sizes. EPMA analysis indicated that the Na-rich area is composed of Ab: 81%, Or: 3% and An: 11% in average, while the K-rich area is composed of Ab: 45%, Or: 44% and An: 11 % in average. TEM analysis revealed albite with Albite twins in the Na-rich area, contrasting to mixtures of albite with fine Albite twins and orthoclase without twins, forming regular lamella of about 100 nm sizes, in the K-rich area. The [001] electron diffraction pattern of the K-rich area also indicated coexistence of the two phases. While streaking parallel to the (010)$^{*}$ direction appeared only in albite due to the twin structure, streaking parallel to the $(100)^{ *}$ direction appeared both in albite and orthoclase, probably due to strain on the interface as well as order-disorder phenomena of Al and Si. It is suggested that the reverse orientation of albite and orthoclase is caused by pole switching to reduce strain on their interfaces. Based on these observations and analyses, the mineral studied is identified as lower-temperature cryptoperthite rather than high-temperature anorthoclase, which has a midium degree of Al-Si ordering and $400^{\circ}C$∼$600^{\circ}C$ of estimated temperatures for the microstructure formation.

• Conservation Science in Museum
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• v.13
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• pp.37-44
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• 2012

White crystals on 46 costumes excavated from Shim Su-Ryun(1534 - 1589)'s tomb were examined their characterization and distribution. In 36 of such samples, white crystals with different shape and hardness were found. The formation of crystals did not correlated with a kind and use of textiles. However, crystals were found in the back side than the front of costume, specially around the marks of shrouding dead body. White crystals from 7 textiles were investigated by EPMA, XRD, or FT-IR. The composition of white crystal was analysed by EPMA and the structure characterization of crystals was used by X-ray diffraction. FT-IR spectroscopy was applied to check if non-crystalline compounds were also present. Mg and P were detected as the main element of white crystals and these compounds were identified a struvite and newberyite, the inorganic mineral magnesium ammonium phosphates. Struvite precipitation are influenced by many factors including concentration of Mg²⁺, NH₄⁺, and PO₄^3- ions, pH, and temperatures. It is assumed that magnesium, phosphorous, ammonia, a base material of struvite comes from decomposition product of human body. Tomb covered with lime, a unique triple-structure in Joseon period offering the basic condition, an anaerobe in a coffin, and high magnesium concentration of outer coffin with lime can be inferred as important factor for precipitation of crystals.

• Korean Chemical Engineering Research
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• v.44 no.4
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• pp.375-381
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• 2006

In this sturdy, spherical activated carbon(SPAC) contained $TiO_2$ was made by ion-exchanged treatment and heat treatment for applying fluidizing bed system. The ion-exchange resin was treated by $TiCl_3$ aqueous solution. The treated resin and raw resin were heat-treated under nitrogen condition to convert into Ti-SPAC. During the heat-treatment, burn-off weight amounts and the element were measured by means of TGA and TGA/MS, individually. The physicochemical properties of Ti-SPAC was characterized by means of XRD, SEM, EDS, BET, EPMA, ESR, intensity and titanium content. The Ti-SPAC had spherical shape with diameter size about $350{\mu}m{\sim}400{\mu}m$ and $617m^2/g$ specific surface area. Structure of $TiO_2$ in Ti-SPAC was anatase and rutile form. Also, $TiO_2$ on SPAC were found that the $TiO_2$ were uniformly distributed through EPMA analysis. Moreover, the Ti-SPAC showed indirect photocatalyst activity estimation through ESR analysis, characteristics of photocatalyst potentially. Over all results, Ti-SPAC was used in fluidizing bed UV/photocatalyst system to remove HA(Humic Acid). That results were HA removal efficiency was about 70％ and Ti-SPAC intensity was preserved during reaction. Ti-SPAC showed practical possibility as photocatalyst in fluidizing bed system.

• Journal of the Korean Ceramic Society
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• v.40 no.9
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• pp.916-920
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• 2003

The change of structure and morphology in ( $U_{0.913}$G $d_{0.087}$) $O_2$ during oxidation at 475$^{\circ}C$ and heat treatment at 130$0^{\circ}C$ in air were investigated using XRD, SEM, and EPMA. The ( $U_{0.913}$G $d_{0.087}$) $O_2$ cubic phase converted to ( $U_{0.913}$G $d_{0.087}$)$_3$ $O_{8}$ orthorhombic phase by oxidation at 475$^{\circ}C$ in air. The XRD and EPMA result of the 130$0^{\circ}C$ heat treated powder revealed that ( $U_{0.913}$G $d_{0.087}$)$_3$ $O_{8}$ orthorhombic phase was separated into $U_3$ $O_{8}$ and ( $U_{0.67}$G $d_{0.33}$) $O_{2+}$x/ cubic phase. The weight variations of (U,Gd) $O_2$ with various Gd contents were measured using TGA at the same heat treated condition. The weight variation during the heat treatment of Gd dissolve (U,Gd) $O_2$ in air can be expressed in terms of phase reaction equations related with oxidation and phase separation. Based on these phase reaction, a initial content of Gd dissolved in (U,Gd) $O_2$ can be exactly calculated by measuring the weight change during the heat treatment.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2005.11a
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• pp.275-277
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• 2005

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2008.05a
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• pp.127-128
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• 2008

• 한국전자현미경학회:학술대회논문집
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• 1994.05a
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• pp.31-31
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• 1994