• Journal of Advanced Marine Engineering and Technology
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• 제38권9호
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• pp.1039-1044
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• 2014

가혹한 조건에서 작동하는 디젤엔진의 윤활성능을 향상시키기 위하여 많은 연구가 진행되고 있다. 본 연구에서는 특수윤활제로 사용되고 있는 나노다이아몬드를 포함한 윤활제를 디젤엔진에 적용하여 엔진성능에 미치는 영향을 분석하고자 한다. 매트릭스 합성분산법에 의하여 제조된 나노다이아몬드 윤활제를 농도별로 실험하여 기본윤활제와 비교하였다. 실험결과 마찰저감에 의한 효율의 향상과 일산화탄소, 스모크 등의 배기 저감의 효과를 확인하였다.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part2
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• pp.1148-1148
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• 2006

• 한국진공학회:학술대회논문집
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• 한국진공학회 2012년도 제43회 하계 정기 학술대회 초록집
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• pp.418-418
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• 2012

Synthesis of nanocrystalline diamond powder was investigated via a gas-to-particle scheme using the hot filament chemical vapor deposition. Effect of substrate surface seeding by nano diamond powder, and that of the electrical conductance of the substrate were studied. The substrate temperature, methane content in the precursor gas, filament-substrate distance and filament temperature were $670^{\circ}C$, 5% methane in hydrogen, 10 mm and $2400^{\circ}C$, respectively. The powder formation by gas-to-particle mechanism were greatly enhanced by the substrate seeding by the nano diamond powder. It was attributed to the removal of the electrostatic force between the substrate and the seeded nano diamond particle by the thermal electron shower from the hot filament, via the depolarization of the substrate surface or the attached diamond powder and subsequent levitation into the gas phase to serve as the gas-phase nucleation site. The powder formation was greatly favoured by the conducting substrate relative to the insulating substrate, which proved the actual effect of the electric static force in the powder formation.

• Design & Manufacturing
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• 제14권1호
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• pp.63-68
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• 2020

Ultra-high brightness and thin displays need to optical micro-patterns which can uniformly diffuse the lights and low loss. The micro random patterns have characteristics to rise the optical efficiency such as light extraction, uniform diffusion. For this reason, various fabrication processes are studied for random patterns. In this study, the micro random patterns were machined by diamond turning which used a controlled cutting tool path with random cutting depth. The machined patterns had random shape and directionality along the circumferential direction. The average width and length of machined random pattern according to rotation radius were 40.13㎛~55.51㎛ and 37.25㎛~59.49㎛, and these results were compared with the designed result. Also, the machining error according to rotation radius in diamond turning using randomly controlled cutting depth was discussed.

• 열처리공학회지
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• 제33권3호
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• pp.124-128
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• 2020

Recently, many studies on growth of single crystal diamond using MPECVD have been conducted. The heteroepitaxial method is one of the methods for growing diamonds on a large-area substrate, and research on synthesis of single crystal diamonds using SrTiO₃, MgO, and sapphire substrates has been attempted. In addition, research is being conducted to reduce the internal stress generated during diamond growth and to improve the crystallinity of the diamond. The compressive stress generated therein causes peeling and bowing from the substrate. This study aimed to synthesize heteroepitaxial single crystal diamonds with high crystallinity by surface modification. A diamond thin film was first grown on a sapphire/Ir substrate by MPECVD, and then etched with H₂ gas to modified the morphology and roughness of the surface. A secondary diamond layer was grown on the surface, and the internal stress, crystallinity of the diamond were investigated. As a result, the fabrication of single crystal diamonds with improved crystallinity was confirmed.

• Nano
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• 제13권10호
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• pp.1850121.1-1850121.11
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• 2018

In this study, a series of $LaMnO_3$-diamond composites with varied $LaMnO_3$ mass contents supported on micro-diamond have been synthesized using a sol-gel method. The as-prepared composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy and the Fourier transform infrared spectra (FTIR). Meanwhile, the photocatalytic performances were also tested by photoluminescence (PL) spectroscopy, ultraviolet-visible diffuse reflection spectra (UV-Vis DRS) and the degradation of weak acid red C-3GN (RC-3GN). Results show that the peak position of $LaMnO_3$ is shifted to low angle after the introduction of diamond, and perovskite particles uniformly distributed on the surface of diamond, forming a network structure, which can increase the active sites and the absorption of dye molecules. When the mass ratio of $LaMnO_3$ and diamond is 1:2 (LMO-Dia-2), the composite shows the most excellent photocatalytic activity. This result offers a sample route to enlarge the range of the application of micro-diamond and provide a new carrier for perovskite photocatalysts.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2006년도 춘계학술대회 논문집
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• pp.109-112
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• 2006

A fluorine-doped diamond-like carbon (F-DLC) stamp which has high contact angle, high UV-transmittance and sufficient hardness, was fabricated using the following direct etching method: F-DLC is deposited on a quartz substrate using DC and RF magnetron sputtering, PMMA is spin coated and patterned using e-beam lithography and finally, $O_2$ plasma etching is performed to transfer the line patterns having 100 nm line width, 100 nm line space and 70 nm line depth on F-DLC. The optimum fluorine concentration was determined after performing several pre-experiments. The stamp was applied successfully to UV-NIL without being coated with an anti-adhesion layer.

• 한국분말재료학회지
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• 제20권5호
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• pp.355-358
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• 2013

Micro trench structures are applied in gratings, security films, wave guides, and micro fluidics. These micro trench structures have commonly been fabricated by micro electro mechanical system (MEMS) process. However, if the micro trench structures are machined using a diamond tool on large area plate, the resulting process is the most effective manufacturing method for products with high quality surfaces and outstanding optical characteristics. A nonferrous metal has been used as a workpiece; recently, and hybrid materials, including polymer materials, have been applied to mold for display fields. Thus, the machining characteristics of polymer materials should be analyzed. In this study, machining characteristics were compared between nonferrous metals and polymer materials using single crystal diamond (SCD) tools; the use of such materials is increasing in machining applications. The experiment was conducted using a square type diamond tool and a shaper machine tool with cutting depths of 2, 4, 6 and 10 ${\mu}m$ and a cutting speed of 200 mm/s. The machined surfaces, chip, and cutting force were compared through the experiment.

• 한국윤활학회:학술대회논문집
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• 한국윤활학회 2003년도 학술대회지
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• pp.72-77
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• 2003

Nano-diamonds were added to Ultra-high molecular weight polyethylene (UHMWPE) to improve the tribological properties of UHMWPE. Nano-diamonds which have a diameter of about 5-10nm were produced by detonation. UHMWPE/nano-diamonds composites were fabricated by hot pressing method. It is shown that friction coefficient was increased and wear resistance was improved as nano-diamonds were added to UHMWPE because of excellent mechanical properties of nano-diamonds located on UHMWPE surface.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.434-434
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• 2011

Electrochemical method have been employed in this work to modify the chemical vapour deposited nitrogen doped hydrogen amorphous diamond-like carbon (N-DLC) film to fabricate nickel and copper nano particle modified N-DLC electrodes. The electrochemical behaviour of the metal nano particle modified N-DLC electrodes have been characterized at the presence of glucose in electrolyte. Meanwhile, the N-DLC film structure and the morphology of metal nano particles on the N-DLC surface have been investigated using micro-Raman spectroscopy, X-ray photoelectron spectroscopy and atomic force microscopy. The nickel nano particle modified N-DLC electrode exhibits a high catalytic activity and low background current, while the advantage of copper modified N-DLC electrode is drawn back by copper oxidizations at anodic potentials. The results show that metal nano particle modification of N-DLC surface could be a promising method for controlling the electrochemical properties of N-DLC electrodes.