• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2010년도 추계학술대회 논문집
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• pp.401-402
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• 2010

• 한국주조공학회지
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• 제12권4호
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• pp.346-354
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• 1992

In Al-Pb monotectic alloys Pb particles are difficult to uniformly distribute over the Al matrix because of the gravity segregation of pb element. Therefore the effects of centrifugally spray casting process on microstructures and distributions of Pb particle were investigated. As the preform thickened the sine of Pb particle became larger, the amount of porosity became lower and microstructures showed the change from spray-deposition microstructures in the lower part of the preform to spray-casting microstructures in the upper part of it. The size of Pb particles, amount of porosity and splat layer boundaries in hot forged preform showed still less than of as-deposited preform.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 추계학술대회 초록집
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• pp.37.2-37.2
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• 2010

Electrostatic spray deposition is an innovative coating technique that produces fine, uniform, self-dispersive (due to the Coulombic repulsion), and highly wettable, atomized drops. Copper-indium salts are dissolved in an alcohol-based solvent, which is then electrostatically sprayed onto a moderately heated, molybdenum-coated substrate. Solvent flowrates range from 0.02 to 5 ml/hr under applied voltages of 1 to 20 kV yielding drop sizes around a few hundred nanometers. By comparing the scanning electron miscrscope images of coated samples, the substrate temperature, applied voltage, solvent flowrate, and nozzle-substrate distance are demonstrated to be the primary parameters controlling coating quality. Also, the most stable electrostatic spray mode that reliably produces uniform and fine drops is the cone-jet mode with a Taylor cone issuing from the nozzle.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2011년도 제42회 하계학술대회
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• pp.1408-1409
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• 2011

Carbon nanotubes (CNTs) were grown on conical tip substrates by using various methods such as electrophoretic deposition, dip-coating, and spray. The scanning electron microscope measurement showed that the spray method ascertained the most uniform deposition of CNTs. The CNT-emitter that was fabricated by the spray method revealed the lowest turn on voltage of electron emission and the highest emission current. In addition, the spray-produced CNT emitter showed the most stable long-term emission characteristics.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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• pp.240-241
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• 2006

Metal/diamond binary composite coatings on Al substrate without grit blasting were deposited by cold spray process with insitu powder preheating. Microstructural characterization of the as-sprayed coatings with different diamond size, strength and with/without Ti coating on diamond was carried out by OM and SEM. The assessment of basic properties such as tensile bond strength and hardness of the coatings, and the deposition efficiency was also carried out. Particular attention on the composite coatings was on the diamond fracture phenomenon during the cold spray deposition and the interface bonding between the diamond and the Fe-based metal matrix.

• 한국재료학회지
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• 제21권2호
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• pp.106-110
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• 2011

A high thermal conductive AlN composite coating is attractive in thermal management applications. In this study, AlN-YAG composite coatings were manufactured by atmospheric plasma spraying from two different powders: spray-dried and plasma-treated. The mixture of both AlN and YAG was first mechanically alloyed and then spray-dried to obtain an agglomerated powder. The spray-dried powder was primarily spherical in shape and composed of an agglomerate of primary particles. The decomposition of AlN was pronounced at elevated temperatures due to the porous nature of the spray-dried powder, and was completely eliminated in nitrogen environment. A highly spherical, dense AlN-YAG composite powder was synthesized by plasma alloying and spheroidization (PAS) in an inert gas environment. The AlN-YAG coatings consisted of irregular-shaped, crystalline AlN particles embedded in amorphous YAG phase, indicating solid deposition of AlN and liquid deposition of YAG. The PAS-processed powder produced a lower-porosity and higher-hardness AlN-YAG coating due to a greater degree of melting in the plasma jet, compared to that of the spray-dried powder. The amorphization of the YAG matrix was evidence of melting degree of feedstock powder in flight because a fully molten YAG droplet formed an amorphous phase during splat quenching.

• 한국표면공학회지
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• 제41권6호
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• pp.255-263
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• 2008

Generally, deposition mechanism of diamond particle is mainly embedding effect in the kinetic spray process. Accordingly, in spite of high cost, helium gas was employed as process gas to get high diamond fraction in the composite coating. In this study, the deposition behavior of bronze/diamond by kinetic spray process was compared using different process gas (helium and nitrogen). Bare (mean size of $5{\mu}m$, $20{\mu}m$) and nickel coated diamond (mean size of $26{\mu}m$) were deposited on Al 6061-T6 substrate with fixed process temperature and pressure. For comparison with experimental results, plastic deformation behavior of nickel layer was simulated by finite element analysis (using ABAQUS/Explicit 6.7-2). The size, broken ratio, and fraction of diamond in the composite coating were analyzed through scanning electron microscopy and image analysis method. The uniform distribution and deposition efficiency of diamond particles in the coating layer could be achieved by tailoring the physical properties of the feedstock.

• 한국표면공학회:학술대회논문집
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• 한국표면공학회 2017년도 춘계학술대회 논문집
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• pp.90-90
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• 2017

Cold spray (Cold gas dynamic spray, kinetic spray) is the latest spray coating process that is known as solid state deposition process. In cold spray, inert gases (typically nitrogen and helium) accelerate powder particles prior to impact onto the substrate. Accelerating particles start to deposit onto the substrate after reaching certain critical velocities depending on the coating materials and substrate. Since process gas temperatures are kept below to melting temperature of the coating materials, it is possible to spray temperature sensitive materials such as copper and titanium, nanocrystal materials, and amorphous metals without affecting the phase change and oxide formation. It is also possible to deposit thick coatings because cold spray coatings present compressive residual stresses. This ability to deposit thick coatings is suitable to repair or rebuild parts as an additive manufacturing process. In this presentation, cold spray is introduced and compared to other additive manufacturing processes such as laser and electron beam based processes. It is also presented some applications especially in the view point of additive manufacturing process.

• 한국표면공학회지
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• 제46권6호
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• pp.258-263
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• 2013

4 mol% Yttria-stabilized zirconia (4YSZ) coatings are fabricated by Air Plasma Spray (APS) and Electron Beam Physical Vapor Deposition (EB-PVD) with top coating of thermal barrier coating (TBC). NiCrAlY based bond coat is prepared as 150 ${\mu}m$ thickness by conventional APS (Air Plasma Spray) method on the NiCrCoAl alloy substrate before deposition of top coating. Each 4YSZ top coating shows different tribological behaviors based on the inherent layer structures. 4YSZ by APS which has splat-stacked structure shows lower friction coefficient but higher wear rate than 4YSZ by EB-PVD which has columnar structure. For 4YSZ by APS, such results are expected due to the sliding wear accompanied with local delamination of splats.

• 대한기계학회논문집B
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• 제35권9호
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• pp.969-974
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• 2011

탄소나노튜브(CNT)는 원통형의 탄소나노 구조물로서, 뛰어난 전도특성과 열전도율을 갖는다. 이러한 특성을 이용한 다양한 응용 분야의 하나로 CNT 를 박막형태의 그물망으로 제작하여 전도성 필름으로 응용하는 방안이 연구되고 있다. 이러한 CNT 의 박막 제조 방법 중, 분무 코팅 방식은 대면적 박막 제조에 널리 사용되나, 박막 두께를 균일하게 제작하는 점에 어려움이 있다. 이러한 문제점을 해결하려면 분무시의 공정조건이 증착 두께 분포에 미치는 효과를 잘 분석해야 한다. 본 연구에서는 분무 공정에서의 증착두께분포를 예측하기 위한 수치해석 모델을 개발하였다. 또한, 개발된 모델을 이용하여 여러가지 노즐 경로에 따른 증착 두께 분포를 분석하였다.