• Applied Microscopy
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• 제43권2호
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• pp.88-97
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• 2013

Technical investigation to figure out the problems arising during in-situ heating electron backscatter diffraction (EBSD) analysis inside scanning electron microscopy (SEM) was carried out. EBSD patterns were successfully acquired up to $830^{\circ}C$ without degradation of EBSD pattern quality in steels. Several technical problems such as image drift and surface microstructure pinning were taking place during in-situ experiments. Image drift problem was successfully prevented in constant current supplying mode. It was revealed that the surface pinning problem was resulted from the $TiO_2$ oxide particle formation during heating inside SEM chamber. Surface pinning phenomenon was fairly reduced by additional platinum and carbon multi-layer coating before in-situ heating experiment, furthermore was perfectly prevented by improvement of vacuum level of SEM chamber via leakage control. Plane view in-situ observation provides better understanding on the overall feature of recrystallization phenomena and cross sectional in-situ observation provides clearer understanding on the recrystallization mechanism.

• 한국전기전자재료학회논문지
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• 제13권2호
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• pp.125-130
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• 2000

Two step growth of reduced pressure chemical vapor eposition has been successfully developed to achieve in-situ phosphorus-doped silicon epilayers, and the characteristic evolution on their microstructures has been investigated using scanning electron microscopy, transmission electron microscopy, and secondary ion mass spectroscopy. The two step growth, which employs heavily in-situ P doped silicon buffer layer grown at low temperature, proposes crucial advantages in manipulating crystal structures of in-situ phosphorus doped silicon. In particular, our experimental results showed that with annealing of the heavily P doped silicon buffer layers, high-quality epitaxial silicon layers grew on it. the heavily doped phosphorus in buffer layers introduces into native oxide and plays an important role in promoting the dispersion of native oxides. Furthermore, the phosphorus doping concentration remains uniform depth distribution in high quality single crystalline Si films obtained by the two step growth.

• 한국재료학회지
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• 제17권1호
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• pp.25-30
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• 2007

The in-situ scanning electron microscopy observation of real-time hillock evolution in pure hi thin films on glass substrate during Isothermal annealing was analyzed quantitatively to understand the compressive stress relaxation mechanism by focusing on the effect of Mo interlayer between Al film and glass substrate. There is a good correlation between the hillock-induced stress relaxation by in-situ scanning electron microscopy observation ana the measured stress relaxation by wafer curvature method. It is also clearly shown that the existence of Mo interlayer plays an important role in hillock formation probably due to the large difference in interfacial diffusivity of Al films.

• Corrosion Science and Technology
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• 제14권6호
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• pp.301-312
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• 2015

Corrosion of zirconium fuel cladding is known to limit the lifetime and reloading cycles of fuel in nuclear reactors. Oxide layers formed on ZIRLO4^{TM}$ cladding samples, after immersion for 300-hour and 50-day in a simulated primary water chemistry condition ($360^{\circ}C$ and 20 MPa), were analyzed by using the scanning transmission electron microscopy (STEM), in-situ transmission electron microscopy (in-situ TEM) with the focused ion beam (FIB) technique, and X-ray diffraction (XRD). Both samples (immersion for 300 hours and 50 days) revealed the presence of the ZrO sub-oxide phase at the metal/oxide interface and columnar grains developed perpendicularly to the metal/oxide interface. Voids and micro-cracks were also detected near the water/oxide interface, while relatively large lateral cracks were found just above the less advanced metal/oxide interface. Equiaxed grains were mainly observed near the water/oxide interface.

• Applied Microscopy
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• 제24권3호
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• pp.87-93
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• 1994

In order to elucidate the machinability of lead brass, orthogonal machining experiment was conducted in SEM(Scanning Electron Microscope) equipped with a micro-machining device at a cutting speed of $7{\mu}m/s$ for brass containing 0.2 to 3wt% Pb. The microfactors (i.e., shear angle, contact length between chip and tool) were determined by in-situ observations. Machinability of brass containing lead is discussed in terms of the microfactors and the cutting resistant force tested by lathe cutting. The dynamic behavior of the chip formation of lead brass during the machining process was examined: The chips of lead brass form as a shear angle type. The shear angle increases with the content of lead in (6:4) brass. The pronounced effect of lead on the contact length between chip and tool was observed above 1% Pb. The cutting resistant force tested by lathe decreases remarkably with the lead content in brass. The observed microfactors are in close relation to the tested resistant force in macromachining.

• 대한금속재료학회지
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• 제48권8호
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• pp.780-789
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• 2010

The aim of this study is to evaluate the microstructure and tensile property of in-situ (TiB+TiC) particulate reinforced titanium matrix composites (TMCs) synthesized by the investment casting process. Boron carbide ($1,500{\mu}m$ and $150{\mu}m$) was added to the titanium matrix during vacuum induction melting, which can provide the in-situ reaction of $5Ti+B_4C{\rightarrow}4TiB+TiC$. 0.94, 1.88 and 3.76 wt% of $B_4C$ were added to the melt. The phases identification of the in-situ synthesized TMCs was examined using scanning electron microscopy, an X-ray diffractometer, an electron probe micro-analyzer and transmission electron microscopy. Tensile properties of TMCs were investigated in accordance with the reinforcement size and volume fraction. The improvement of tensile property of titanium matrix composites was caused by load transfer from the titanium matrix to the reinforcement and by grain refinement of titanium matrix and reinforcements.

• Food Science and Biotechnology
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• 제18권2호
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• pp.432-435
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• 2009

The preventive effect of chewing gum containing maltitol, xylitol, gum base, and sugar on remineralization were investigated. The clinical study consisted of 8 weeks' randomized, double blind, controlled, cross-over clinical trials including 24 healthy adults had chew gum. After each test week, remineralization effect was evaluated by measuring microhardness and scanning electron microscopy (SEM). Microhardness of experimental chewing gum containing maltitol or xylitol was significantly higher than that of sugar gum (p<0.005). Images of SEM showed the remineralization effect of gum containing gum base, maltitol, or xylitol compared with sugar gum. Maltitol and xylitol gums were more effective in remineralization than sugar gum. It was concluded that maltitol and xylitol can be used as sugar substitute to prevent dental caries.

• 마이크로전자및패키징학회지
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• 제12권4호통권37호
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• pp.281-287
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• 2005

공정조성의 SnPb 솔더 선형시편에서 electromigration 현상을 실시간 주사전자현미경을 이용하여 관찰하였다. 공정조성 SnPb 솔더시편에 대한 electronigration 실험은 ${\times}10^4A/cm^2,\;90^{\circ}C$에서 실시하였다. 주사전자현미경 챔버 내에서 진행되는 electromigration 실험 동안 음극의 보이드 형성과 양극의 힐록 성장을 실시간으로 관찰하였다. 음극에서 일어나는 보이드 크기를 실시간 관찰한 결과, 공정조성 SnPb 솔더의 electromigration 거동은 보이드 형성 전에 가지는 잠복기의 존재를 명확히 알 수 있었고, 본 결과는 electromigration 거동으로 인한 플립칩 솔더 범프의 보이드 생성에 대한 잠복기와 관련이 있었다.

• Applied Microscopy
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• 제52권
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• pp.7.1-7.6
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• 2022

The process of encapsulating cobalt nanoparticles using a graphene layer is mainly direct pyrolysis. The encapsulation structure of hybrids prepared in this way improves the catalyst stability, which greatly reduces the leaching of non-metals and prevents metal nanoparticles from growing beyond a certain size. In this study, cobalt particles surrounded by graphene layers were formed by increasing the temperature in a transmission electron microscope, and they were analyzed using scanning transmission electron microscopy (STEM). Synthesized cobalt hydroxide nanosheets were used to obtain cobalt particles using an in-situ heating holder inside a TEM column. The cobalt nanoparticles are surrounded by layers of graphene, and the number of layers increases as the temperature increases. The interlayer spacing of the graphene layers was also investigated using atomic imaging. The success achieved in the encapsulation of metallic nanoparticles in graphene layers paves the way for the design of highly active and reusable heterogeneous catalysts for more challenging molecules.

• Journal of Ginseng Research
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• 제26권4호
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• pp.213-218
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• 2002

본 연구는 인삼에 존재하는 calcium oxalate 결정체의 분포 위치, 형태 및 미세구조에 관하여 밝히고자 광학현미경, 조직화학적 방법 및 주사 전자현미경적 방법 등을 사용하여 연구 하였다. 인삼의 결정체는 calcium oxalate의 성분으로 구성되며, 결정체는 몸통뿌리, 지근, 뇌두, 줄기, 장엽병, 소엽병, 꽃대 등 대부분의 기관에서 관찰되었다 특히 지상부는 잎에서,지하부는 뇌두에서 가장 많은 결정체가 관찰되었다. 인삼에 존재하는 결정체는 silver nitrate-rubeanic acid를 사용한 조직화학적 반응을 실시한 결과 calcium oxalate치 성분으로 확인되었다. 또한 주사전자현미경으로 관찰한 결과 삼각뿔 형태의 결정체가 다수 모여서 형성된 유형, 프리즘 형태의 소결정이 모여서 형성된 유형 및 얇은 판상의 소결정이 모여서 형성된 유형 등 3가지 형태로 구분 할 수 있었다.