• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2002.05a
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• pp.86-89
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• 2002

Due to extremely large reduction of area or extrusion ratio in ordinary production of extruded profiles, anisotropy is naturally induced by large severe deformation during the extrusion process. Therefore, the anisotropic properties play a great role in the post processing of extruded profiles, such as in bending. Moreover, undesirable deformation will be involved when the deformation-induced anisotropy is ignored. In order to observe the deformation-induced anisotropy of the thin-walled product, the proposed algorithm is applied to some chosen industrial extrusion processes. In the resent work, the method for prediction of deformation-induced anisotropy employing the Barlats six-component yield potential to the rigid-plastic finite element method is proposed. The proposed algorithm is verified with the comparison to the crystallographic texture analysis, and then applied to the C-section exclusion process using a square die. The predicted anisotropy is then compared with the experimental and computational observations for validating the proposed algorithm.

• Transactions of Materials Processing
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• v.11 no.8
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• pp.724-730
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• 2002

Due to extremely large reduction of area or extrusion ratio in ordinary production of extruded profiles, anisotropy is naturally induced by large severe deformation during the extrusion process. Therefore, the anisotropic properties play a great role in the post processing of extruded profiles, such as in bending. Moreover, undesirable deformation will be involved when the deformation-induced anisotropy is ignored. In order to observe the deformation-induced anisotropy of the thin-walled product, the proposed algorithm is applied to some chosen industrial extrusion processes. In the present work, the method for prediction of deformation-induced anisotropy employing the Barlats six-component yield potential to the rigid-plastic finite element method is proposed. The proposed algorithm is verified with the comparison to the crystallographic texture analysis, and then applied to the C-section extrusion process using a square die. The predicted anisotropy is then compared with the experimental and computational observations for validating the proposed algorithm.

• Korean Journal of Crystallography
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• v.9 no.2
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• pp.85-91
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• 1998

고주파 마그네톤 스퍼터법을 이용하여 ZnO 박막 증착시, 증착 조건, 증착 후 표면스퍼터 및 열처리 분위기에 따른 ZnO 박막의 표면조직과 전기적 특성을 분석하였다. ZnO 박막의 면저항은 500℃에서 행한 증착후 열처리의 분위기에 따라 수 GΩ/ㅁ에서 수 KΩ/ㅁ까지 변하였다. 이들 박막의 전하운반자 농도는 1015∼1018/㎤이었으며, 이동도는 10∼40㎠Vsec이었다. 특정한 스퍼터 조직에서 박막의 표면을 스퍼터할 경우 박막 표면적이 증가하였으며, 이러한 박막의 분위기 열처리에 민감한 반응을 보였다. 증착한 박막과 증착후 열처리한 박막의 화학조성 비교를 통하여, 박막의 원자결함 유형 및 전기적 특성을 미치는 이들의 영향에 관한 고찰을 하였다.

• Proceedings of the Korean Institute of Surface Engineering Conference
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• 2015.05a
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• pp.123-123
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• 2015

0.087 wt.% Gd-lean duplex stainless steels were inert arc-melted and cast in a mold. The micro-hardnesses of the rolling, transverse, short transverse directions were 258.5, 292.3, 314.7 HV, respectively. The 33% cold rolled specimen had the crystallographic texture that mainly (100) pole was concentrated to normal direction and (110) pole was concentrated in the center of normal and rolling directions. The corrosion potential and corrosion rate in artificial sea water were in the range of $105.6-221.6mV_{SHE}$, $0.59-1.06mA/cm^2$, respectively. The friction coefficient and wear loss of the 0.087 wt.% Gd-lean duplex stainless steels in artificial sea water were about 67% and 65% lower than in air, whereas, the wear efficiency was 22% higher. The corrosion and wear behaviors of the 0.087 wt.% Gd-lean duplex stainless steels significantly depended on the gadolinium phases.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.6
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• pp.281-286
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• 2021

Arc ion plating (AIP), laser cladding, and nitriding are methods that can prevent mold damage or repair and create cracks and breakages on the die surface. The dissolution and soldering behavior of coated SKD61 by using arc ion plating, laser cladding, and nitriding was investigated. The structure of the coating was investigated as a function of deposition conditions by X-ray diffraction and the crystallographic orientation was determined using the texture factor. The TiAlN film deposited with AIP showed excellent corrosion resistance in the molten aluminum alloy at 680℃. In this paper, we have detailed the corrosion and mass loss phenomena associated with these steel-cast metal interactions.

• Journal of the Microelectronics and Packaging Society
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• v.16 no.3
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• pp.61-65
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• 2009

We produced noble surface structure of crystalline Si for solar cells by using preferential aqueous etching on crystallographic defects which were induced by grinding process. We analyzed the reflectance of textured surface according to surface topography resulting from various etchant concentrations and duration of etching process. The crystallographic defects and textured surface topography were investigated by using transmission electron microscopy and secondary electron microscopy, respectively. Also, the measurement of reflectance of textured surface utilizes spectrophotometer. The optimized texture surface exhibits improved result indicating reflectance of below ave. 1%. And it is cost-effective as well as taking short time within a few minutes.

• Journal of the Korean institute of surface engineering
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• v.56 no.3
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• pp.192-200
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• 2023

Graphene, a two-dimensional material, has shown great potential in a variety of applications including microelectronics, optoelectronics, and graphene-based batteries due to its excellent electronic conductivity. However, the production of large-area, high-quality graphene remains a challenge. In this study, we investigated graphene growth on electrolytic copper foil using thermochemical vapor deposition (TCVD) to achieve a similar level of quality to the cold-rolled copper substrate at a lower cost. The combined effects of pre-annealing time, graphenized temperature, and partial pressure of hydrogen on graphene coverage and domain size were analyzed and correlated with the roughness and crystallographic texture of the copper substrate. Our results show that controlling the crystallographic texture of copper substrates through annealing is an effective way to improve graphene growth properties, which will potentially lead to more efficient and cost-effective graphene production. At a hydrogen partial pressure that is disadvantageous in graphene growth, electrolytic copper had an average size of 8.039 ㎛², whereas rolled copper had a size of 19.092 ㎛², which was a large difference of 42.1% compared to rolled copper. However, at the proper hydrogen partial pressure, electrolytic copper had an average size of 30.279 ㎛² and rolled copper had a size of 32.378 ㎛², showing a much smaller difference of 93.5% than before. This observation suggests this potentially leads the way for more efficient and cost-effective graphene production.

• Journal of the Microelectronics and Packaging Society
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• v.31 no.2
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• pp.36-44
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• 2024

Copper electrodeposition technology is essential for producing copper films and interconnects in the microelectronics industries including semiconductor packaging, semiconductors and secondary battery, and there are extensive efforts to control the microstructure of these films and interconnects. In this study, we investigated the influence of crystallographic orientation on the local plastic deformation of copper films for secondary batteries deformed by uniaxial tensile load. Crystallographic orientation maps of two electrodeposited copper films with different textures were measured using an electron backscatter diffraction (EBSD) system and then used as initial conditions for crystal plasticity finite element analysis to predict the local plastic deformation behavior within the films during uniaxial tension deformation. Through these processes, the changes of the local plastic deformation behavior and texture of the films were traced according to the tensile strain, and the crystal orientations leading to the inhomogeneous plastic deformation were identified.

• Journal of the Korean Society for Heat Treatment
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• v.31 no.6
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• pp.275-282
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• 2018

Two different modes of rolling were applied to control the texture development in tantalum sheet. In the conventional uni-directional rolling, the typical rolling textures of a body-centered cubic metal which was primarily composed of <110>//(rolling direction) was developed. In a cross rolling where the specimen was rotated by $90^{\circ}$ between each pass, the rotated cube components, i.e. {100}<011> were greatly reinforced. The prediction of lattice rotation by the full-constraint Taylor model showed that the high stability and the symmetry of the rotated cube components caused their strengthening in cross-rolling. The two specimens were heated to $1,100^{\circ}C$ at $9^{\circ}C/min$and held for 1 hour for annealing, then cooled to room temperature in atmosphere. In spite of the significant difference in the deformation textures, the annealing textures were very similar. They developed strong <111>//(plane normal) components with negligible intensity at the rotated cube components, which was attributed to the negligible capability of the latter components to provide effective recrystallized grains.

• Korean Journal of Crystallography
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• v.3 no.2
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• pp.72-84
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• 1992

The investigation has been carried out for purification, single crystal growth mechanism and convective phenomena in EBFZM of Nb metal. It is found that the EBFZM refined effectively oxygen and nitrogen, the interstitial impurities in Nb, but carbon was increased slightly by backstream of diffusion pump oil. The mechanism of single crystal growth associated with the second recrystallieation in Nb was suggested from the relationship between texture of starting materials and the crystal growth in EBFZM. It was observed from the investigation of convection phenomena in molten zone that the Marangoni convection was dominant in molten zone, which caused the striation in Nb and increased the purification effect of oxygen and nitrogen.