• Title/Summary/Keyword: Micro/Nano structures

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WC-Co coating by cold spray deposition (Cold spray를 이용한 WC-Co 코팅)

  • 김형준;황순영;권영각
    • Proceedings of the KWS Conference
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    • 2004.05a
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    • pp.311-313
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    • 2004
  • WC-12-17%Co powders with nano- and micro-structures were deposited by cold spray process using nitrogen and helium gases. The results show that there is no detrimental phase transformation and/or decarburization of WC by cold spray deposition as expected. It is also observed that nano-sized WC in the feedstock powder is maintained in the cold spray deposition. It is demonstrated that it is possible to fabricate the nano-structured WC-Co coating with low porosity and very high hardness (-2050 HV) by cold spray deposition with reasonable powder preheating.

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Enhanced Light Transmittance of Densely Packed Metal Nanoparticle Layers (밀집된 금속 나노 입자 레이어의 광학 특성)

  • Jeon, Hyunji;Choi, Jinnil
    • Korean Journal of Materials Research
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    • v.30 no.12
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    • pp.701-708
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    • 2020
  • Irradiation of the metal nanoparticles causes local plasmon resonance in a specific wavelength band, which can improve the absorption and scattering properties of a structure. Since noble metal nanoparticles have better resonance effects than those of other metals, it is easy to identify plasmonic reactions and this is advantageous to find the optical tendency. Compared to having a particle gap or randomly arranged particle structures, densely and evenly packed structures can exhibit more uniform optical properties. Using the uniform properties, the structure can be applied to optical filtering applications. Therefore, in this paper, validation tests about metal nanoparticles and thin film structures are conducted for more accurate analysis. The optical properties of monolayer and bilayer noble metal nanoparticle structures with different diameters, packed in a uniform array, are investigated and their optical trends are analyzed. In addition, a thin film structure under identical conditions as metal nanoparticle structure is evaluated to confirm the improved optical characteristics.

Polyelectrolyte Micropatterning Using Agarose Plane Stamp and a Substrate Having Microscale Features on Its Surface

  • Lee, Min-Jung;Lee, Nae-Yoon;Lee, Sang-Kil;Park, Sung-Su;Kim, Youn-Sang
    • Bulletin of the Korean Chemical Society
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    • v.26 no.10
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    • pp.1539-1542
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    • 2005
  • We have introduced polyelectrolyte micro-patterning technique employing agarose plane stamp and a hard substrate having microscale features on its surface. With this method, chemically micropatterned surfaces with both positive and negative functionalities were successfully embedded in well-defined microstructures, and selective impartment of charge functionalities was confirmed by patterning bead bearing surface charge. Furthermore, this technique allows highly sensitive immobilization of protein onto targeted surface simply by endowing functionalities, which extends the potential of its use as a tool for high-throughput protein microarray and proteomics. Because plane agarose stamp is free of structures on its surface, there is no concern for pattern collapse, and the combination of agarose plane stamp with patterned substrate is more suited for selective protein patterning compared with adopting surface-patterned agarose stamp with flat substrate. Our technique using agarose plane stamp and a substrate having microscale features on its surface suggests a range of possible applications, including the micropatterning of biofunctionalized copolymer having polyelectrolyte block, immobilization of micro- and nanoparticle with biofunctionalities such as biotin and streptavidine, and establishing optoelectronic microstructures with micro-beads on various surfaces.

Evaluation of micro-channel characteristics of fused silica glass using powder blasting (Powder blasting을 이용한 Fused silica glass의 마이크로 채널 가공 및 특성 평가에 관한 연구)

  • Lee, Jung-Won;Kim, Tae-Min;Shin, Bong-Cheol
    • Design & Manufacturing
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    • v.14 no.1
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    • pp.36-41
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    • 2020
  • Recently, due to the development of MEMS technology, researches for the production of effective micro structures and shapes have been actively conducted. However, the process technology based on chemical etching has a number of problems such as environmental pollution and time problems due to multi-process. Various processes to cope with this process are being studied, and one of the mechanical etching processes is the powder blasting process. This process is a method of spraying fine particles, which has the advantage of being an effective process in manufacturing hard brittle materials. However, it is also a process that adversely affects the material surface roughness and material properties due to the impact of the injection of fine particles. In this study, after fabricating micro-channels in fused silica glass with excellent optical properties among the hard brittle materials, we used the nano indentation system to analyze the micro parts using nano-particles as well as machinability and surface roughness analysis of the processed surface. The analysis was performed for the effective processing of powder blasting.

Structure and magnetic properties of CrN thin films on La0.67Sr0.33MnO3

  • Zhang, Dingbo;Zhou, Zhongpo;Wang, Haiying;Wang, Tianxing;Lu, Zhansheng;Yang, Zongxian;Ai, Zhiwei;Wu, Hao;Liu, Chang
    • Current Applied Physics
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    • v.18 no.11
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    • pp.1320-1326
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    • 2018
  • High crystalline quality CrN thin films have been grown on $La_{0.67}Sr_{0.33}MnO_3$ (LSMO) templates by molecular beam epitaxy. The structure and magnetic properties of CrN/LSMO heterojunctions are investigated combining with the experiments and the first-principles simulation. The N?el temperature of the CrN/LSMO samples is found to be 281 K and the saturation magnetization of CrN/LSMO increases compared to that of LSMO templates. The magnetic property of CrN/LSMO heterostructures mainly comes from Cr atoms of (001) CrN and Mn atoms of (001) LSMO. The (001) LSMO induces and couples the spin of the CrN sublattice at CrN/LSMO interface.

Nano/Micro-friction properties or Chemical Vapor Deposited (CVD) Self-assembled monolayers on Si-wafer

  • Yoon Eui-Sung;Singh R.Arvind;Han Hung-Gu;Kong Hosung
    • Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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    • 2004.11a
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    • pp.90-98
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    • 2004
  • Nano/micro-scale studies on friction properties were conducted on Si (100) and three self-assembled monolayers (SAMs) (PFOTC, DMDM, DPDM) coated on Si-wafer by chemical vapor deposition technique. Experiments were conducted at ambient temperature $(24{\pm}1^{\circ}C)$ and humidity $(45{\pm}5\%)$. Nano-friction was evaluated using Atomic Force Microscopy (AFM) in the range of 0-40nN normal loads. In both Si-wafer and SAMs, friction increased linearly as a function of applied normal load. Results showed that friction was affected by the inherent adhesion in Si-wafer, and in the case of SAMs the physical/chemical structures had a major influence. Coefficient of friction of these test samples was also evaluated at the micro-scale using a micro-tribotester. It was observed that SAMs had superior frictional property due to their low interfacial energies. In order to study of the effect of contact area on friction coefficient at the micro-scale, friction was measured for Si-wafer and DPDM against Soda Lime balls (Duke Scientific Corporation) of different radii 0.25 mm, 0.5 mm and 1 mm at different applied normal loads $(1500,\;3000\;and\;4800{\mu}N)$. Results showed that Si-wafer had higher friction coefficient than DPDM. Furthermore, unlike that in the case of DPDM, friction was severely influenced by wear in the case of Si-wafer. SEM evidences showed that solid-solid adhesion to be the wear mechanism in Si-wafer.

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Fabrication of Microstructures with Nanocomposites by Capillary Effect (모세관법을 이용한 나노 복합재료 마이크로 구조 제작)

  • Han, Soo-Ho;Hwang, Hui-Yun
    • Composites Research
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    • v.31 no.4
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    • pp.171-176
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    • 2018
  • We proposed new and easy fabrication method of micro-nano hierarchical structures for synthetic dry adhesives and conducted feasibility tests of alignment characteristics of nano-materials in the microstructures by capillary effect. Candidates of fabrication conditions were selected based on the degree of cure and viscosity of mixtures of multiwall carbon nanotubes (MWCNTs) and polydimethylsiloxane (PDMS), which were measured with respect to the fabrication conditions. Scanning electron microscopy images of cross sections of MWCNT-PDMS microstructures were analyzed. MWCNT alignment in microstructures was better when fabrication temperature and degree of cure at fabricating start were lower, but areal density of MWCNTs was little affected by fabrication conditions.

A study on mechanical characterization of nano-thick films fabricated by transfer assembly technique (이송조립기술로 제조된 나노 박막의 기계적인 특성 평가에 관한 연구)

  • Choi, Hyun-Ju;Kim, Jae-Hyun;Lee, Sang-Joo;Lee, Hak-Joo
    • Proceedings of the KSME Conference
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    • 2008.11a
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    • pp.30-34
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    • 2008
  • The transfer assembly (or transfer printing) technique is a promising method for fabricating multi-scale structures on various substrates including semiconductors and polymers, and has been applied to fabrication of flexible devices with superior performance to conventional organic flexible devices. The mechanical behaviors of the structures fabricated by the transfer assembly is a very important information for design and reliability evaluation purpose, but the measurement of the behaviors is difficult since their critical-dimensions are very tiny. In this study, Au films with nano-scale thickness were fabricated on a silicon substrate and their mechanical properties were measured using micro-tensile test. The Au films on the silicon substrate were then transferred to a PDMS substrate using the transfer assembly technique. Self-assembled monolayer (SAM) with a thiol group was used to enhance the transfer of Au films, and the mechanical behaviors were characterized using wrinkle-based test. The test results from micro-tensile and wrinkle-based test are compared to each other, and their implication to the transfer assembly technique is discussed.

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Alignment Algorithm for Nano-scale Three-dimensional Printing System (나노스케일 3 차원 프린팅 시스템을 위한 정렬 알고리즘)

  • Jang, Ki-Hwan;Lee, Hyun-Taek;Kim, Chung-Soo;Chu, Won-Shik;Ahn, Sung-Hoon
    • Journal of the Korean Society for Precision Engineering
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    • v.31 no.12
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    • pp.1101-1106
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    • 2014
  • Hybrid manufacturing technology has been advanced to overcome limitations due to traditional fabrication methods. To fabricate a micro/nano-scale structure, various manufacturing technologies such as lithography and etching were attempted. Since these manufacturing processes are limited by their materials, temperature and features, it is necessary to develop a new three-dimensional (3D) printing method. A novel nano-scale 3D printing system was developed consisting of the Nano-Particle Deposition System (NPDS) and the Focused Ion Beam (FIB) to overcome these limitations. By repeating deposition and machining processes, it was possible to fabricate micro/nano-scale 3D structures with various metals and ceramics. Since each process works in different chambers, a transfer process is required. In this research, nanoscale 3D printing system was briefly explained and an alignment algorithm for nano-scale 3D printing system was developed. Implementing the algorithm leads to an accepted error margin of 0.5% by compensating error in rotational, horizontal, and vertical axes.