• Tribology and Lubricants
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• 제27권6호
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• pp.321-325
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• 2011

Nanodiamond was dispersed in paraffin liquid oil to investigate the effects of nanodiamond at the marginally lubricated condition. Scuffing test and immediate loading sliding wear test were conducted using the fabricated nanodiamond oil. As a result, dispersion of nanodiamond in oil leads to increase in scuffing life, and nanodiamond contents affects the scuffing life. In case of immediate loading sliding wear test, the result was different according to hardness of specimen. If hardness of specimen was low, abrasion of nanodiamond occurred actively. If hardness of specimen was increased, however, nanodiamond can act as a spacer or rolling between contacting surfaces.

• 한국산학기술학회논문지
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• 제12권10호
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• pp.4689-4695
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• 2011

나노다이아몬드는 넓은 적용성 측면을 고려한다면 상대적으로 신물질이라 할 수 있다. 본 연구에서는 XRD, EDS, HRTEM, FTIR, Raman 분광기, 열분석 장치와 BET 측정 장치와 같은 다양한 장비를 통해 단결정 폭발 나노다이아몬드와 다결정 합성 나노다이아몬드의 물리화학적 특성들을 고찰하였다. 단결정 폭발 나노다이아몬드는 4nm ~ 6nm 크기의 구형이나 타원 모양이지만, 다결정 합성 다이아몬드는 80nm ~ 120nm 크기의 각이 진 입체도형 모양이다. 단결정과 다결정 나노다이아몬드의 표면은 수산기, 카보닐기, 카복실기 등과 같은 다양한 관능기를 가지고 있다. 질소분위기 하에서 단결정 폭발 나노다이아몬드의 상전이 온도는 대략 $650^{\circ}C$이었다.

• Tribology and Lubricants
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• 제31권4호
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• pp.183-188
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• 2015

This paper presents the experimental effects of lubricant with nanodiamond particles in sliding friction. In order to improve the performance of lubricants many additives are used, such as MoS₂, cadmium chloride, indium, sulfides, and phosphides. These additives are harmful to human health and to the environment, so alternatives are necessary. One such alternative is nanodiamond powder, which has a large surface area. In order to investigate the effect of nanodiamonds in lubricants under sliding friction, they are dispersed in the lubricant at a variety of concentrations (0 wt%, 0.1 wt%, 0.3 wt%, 0.5 wt%, and 1 wt%) using the matrix synthesis method. Friction and wear tests are performed according to the ASTM G99 method using a pin-on-disc tester at room temperature. The specimens used in this experiment are AISI 52100 ball bearings and AISI 1020 steel discs. During the test, lubricant mixed with nanodiamond is supplied constantly to keep the two bodies separated by a lubricant film. To maintain boundary lubrication, the speed is set to 0.18 m/s and a load of 294 N is applied to the disc through the pin. Results are recorded by using workbench software over the test duration of 10 minutes. Experimental results show that when the concentration of nanodiamond increases, the coefficient of friction decreases. However, above a nanodiamond concentration of 0.5 wt%, both the coefficient of friction and wear volume increase. From this experiment, the optimum concentration of nanodiamond showing a minimum coefficient of friction of 0.09 and minimum wear volume of 0.82 nm² was 0.5 wt%.

• 한국분말재료학회지
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• 제18권5호
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• pp.417-422
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• 2011

Hydrophobic nanodiamond (ND) were dispersed in engine oil (Helix Oil, Shell co.) as an additives to improve tribology properties. In this study, nanodiamond prepared by an explosive method was used. Tribology properties of both pure Helix oil and engine oil containing ND additive were evaluated. The rotating disks were made of Gray Cast Iron (240 Hv) and SKD11 (710 Hv). Surface topographies of the disks' wear tracks and friction coefficient were compared. The results show that nanodiamond-dispersed lubricants are capable of reducing these metals' wear loss. The friction coefficient is strongly affected to the hardness of wear track.

• 대한화학회지
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• 제56권2호
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• pp.303-308
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• 2012

• 한국표면공학회지
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• 제39권4호
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• pp.153-159
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• 2006

Nanodiamond films were deposited on Si substrate by introducing a time dependent on/off modulation of $CH_4\;and\;O_2$ flows in a vertical-type microwave plasma enhanced chemical vapor deposition system. Surface morphology and diamond quality of the film were investigated as a function of the on/off modulation time interval. The diamond nucleation density on the substrate was enhanced under low temperature and low pressure condition. In addition, the diamond nucleation density was enhanced by increasing the on/off modulation time interval. Enhanced diamond quality was noticeable under the condition of a longer on/off modulation time interval. It was suggested that the nanodiamond nuclei formed the cluster formation.

• Tribology and Lubricants
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• 제30권5호
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• pp.291-294
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• 2014

Multiple additives can help improve the performance of generally used lubricants. These additives include MoS2, cadmium, chloride, indium, sulfide, and phosphide, which are harmful to both humans and the environment. Thus, researchers in this industry have been trying to reduce the use of these additives by finding alternatives. Nanodiamonds are one of these candidates. Nanodiamond particles are very hard, chemically stable, and highly heat-conductive. This research involved uniformly dispersing nanodiamond particles in marine engine oils via a matrix synthesis method at various concentrations (0, 0.1, 0.3, 0.5, and 1.0 wt). Friction and wear tests involved constant loads on ball-on-disk specimens, where the ball was AISI 51200 steel, the disk was AISI 1020 steel, and the sliding speed was 0.217 m/s. The lowest wear occurred at a suitable concentration of nanodiamonds (0.3 wt). However, excessive amounts of nanodiamonds caused them to act as abrasive debris because of their hardness, which increased the wear amount. The friction coefficient decreased as the nanodiamond concentration increased because their octagonal, almost spherical shape caused them to act as rolling contact elements between two surfaces.

• 통합자연과학논문집
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• 제9권1호
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• pp.16-22
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• 2016

The optical and physical and characteristics of hydrogel ophthalmic lens polymerized with addition of 2,6-difluoropyridine, SiPc(silicon 2,9,16,23-tetra-tert-butyl-29H31H-phthalocyanine dihydroxide) and nanodiamond in the basic hydrogel material were evaluated. In particular, the utility of 2,6-difluoropyridine, SiPc and nanodiamond as a hydrogel ophthalmic lens material was investigated. 2,6-difluoropyridine, SiPc and nanodiamond were used as additives. And also, 2-hydroxyethyl methacrylate, acrylic acid, methyl methacrylate and a cross-linker EGDMA were copolymerized in the presence of AIBN as an initiator. The refractive index of 1.4348~1.4361, water content of 33.30~34.02%, UV-B transmittance of 4.77~67.50%, UV-A transmittance of 1.45~89.19% and visible transmittance of 32.12~92.21% were obtained. The results of hydrogel lens containing 2,6-difluoropyridine (add 5%) showed antibiosis for staphylococcus aureus. The produced copolymer is suitable for hydrogel soft ophthalmic lenses with antibiotic and anti-UV effect.

• 한국결정성장학회지
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• 제29권6호
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• pp.239-244
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• 2019

수소 분위기 열처리 및 수소 플라즈마 처리의 두 가지 수소화 표면개질을통해 나노다이아몬드 seed 입자의 분산 향상 및 평탄한 초미세 나노결정질 다이아몬드 박막증착을 위한 핵형성 밀도 향상을 확보하였다. 수소화 처리 이후 나노다이아몬드 입자 표면의 탄소-산소 및 산소-수소 결합기가 탄소-수소 결합기로 전환되는 화학적 표면개질이 진행되었고 Zeta 전위가 증가하였다. 분산도 향상에 따라 나노다이아몬드 응집체 크기가 현저하게 감소하였고 핵형성 밀도는 크게 증가하였다. 600℃, 수소분위기에서 열처리 이후 나노다이아몬드 평균 입자 크기가 3.5 ㎛에서 34.5 nm로 크게 감소하였고, seeding 된 Si 기판 표면에서 ~3.9 × 10¹¹ nuclei/㎠의 매우 높은 핵형성 밀도를 확보하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.195.2-195.2
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• 2014

Nanodiamond (ND) is composed of inner diamond core and outer graphite shell. The size of ND used in this study was about 5 nm. The ND solution was dropped on silicon substrate and dried in air. Dried ND sample was purified by using annealing method in air. Then, 40 keV Fe ion was irradiated into the sample. The dose was varied from $1{\times}10^{14}$ to $1{\times}10^{16}ions/cm^2$. The post annealing was performed at 1073 K in the vacuum to recover diamond structure. The annealing at 873 K in air was performed to remove the outer graphite shell. The structure of ND was confirmed by X-ray diffraction (XRD) and Raman spectroscopy. We will present the detailed data and results in the conference.