• Journal of the Korean Society for Precision Engineering
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• v.25 no.6
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• pp.40-46
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• 2008

Ultraprecision cutting of steels with geometrically defined single crystal diamond tools is handicapped by excessive tool wear. This paper presents a new approach to suppress the wear of single crystal diamond tool in cutting of steels. In general, it is said that the wear of diamond tool is caused by chemically reactive wear under high temperature and high pressure conditions. In order to suppress such chemical reactions, the time of contact between the diamond tool and the steel work in cutting was controlled by employing the intermittent cutting method such as fly-cutting. Series of intermittent cutting experiments have been carried out to control the tool-work contact time by changing one cycle of cutting length and cutting speed. The experimental results were shown that the tool wear was much dependent on the contact time regardless of the cutting speed, and that the wear was much suppressed by reducing the tool-work contact time. It is expected that the steels can be successfully cut with a single crystal diamond tool by controlling the contact time.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.12
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• pp.16-23
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• 2021

Pin-to-disc wear testing experiments were conducted to investigate the wear characteristics of commercial oil (5W-40) with nano-diamond particles. The upper specimen was a SUJ-2 high-carbon chromium steel ball with a diameter of 4 mm, and the lower specimen was made of the Al-6061 alloy. The applied load was 5 N, and the sliding speed was 0.25 m/s. The wear tests were conducted at a sliding distance of 500 m. The friction coefficients and wear rates of the Al-6061 specimens were tested using commercial oil with different nano-diamond concentrations ranging from 0 to 0.02 wt.%. The addition of nano-diamond particles to commercial oil reduced both the wear rate and coefficient of friction of the Al-6061 alloy. The use of nano-diamond particles as a solid additive in oil lubricants was found to improve the tribological behavior of the Al-6061 alloy. For the Al-6061 alloy, the optimal concentration was found to be 0.005 wt.% in view of the friction coefficient and wear rate. Further investigation is needed to determine the optimal concentration of nano-diamond particles for various loadings, sliding speeds, oil temperatures, and sliding distances.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.4
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• pp.158-164
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• 2023

The meaning of the diamond crystal structure and the formative beauty of the crystal form were designed from a new perspective and expressed in jewelry. In this study, we examined the literature on the crystal structure of diamonds and analyzed cases of jewelry design based on the formative characteristics of diamond crystal structure. we newly interpreted the meaning and value of diamond crystal structure, and studied the figurative design that can show the aesthetic effect of the crystal structure by designing the diamond crystal structure as jewelry. By presenting jewelry designs that take advantage of the symmetry effect of the diamond crystal structure and the repetition of the sculptural beauty, we hope that the fundamental beauty and cultural meaning of gemstones will be re-recognized.

• Proceedings of the Korean Vacuum Society Conference
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• 1999.07a
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• pp.58-58
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• 1999

The diamond films which can be applied to SOD (silicon-on-diamond) structure were deposited on Si(100) substrate using CO/H2 CH4/H2 source gases by microwave plasma chemical vapor deposition(MPCVD), and SOD structure have been fabricated by poly-silicon film deposited on the diamond/Si(100) structure y low pressure chemical vapor deposition(LPCVD). The phase of the diamond film, surface morpholog, and diamond/Si(100) interface were confirmed by X-ray diffraction(XRD), scanning electron microscopy(SEM), atomic force microscopy(AFM), and Raman spectroscopy. The dielectric constant, leakage current and resistivity as a function of temperature in films are investigated by C-V and I-V characteristics and four-point probe method. The high quality diamond films without amorphous carbon and non-diamond elements were formed on a Si(100), which could be obtained by CO/H2 and CH4/H2 concentration ratio of 15.3% and 1.5%, respectively. The (111) plane of diamond films was preferentially grown on the Si(100) substrate. The grain size of the films deposited by CO/H2 are gradually increased from 26nm to 36 nm as deposition times increased. The well developed cubo-octahedron 100 structure nd triangle shape 111 are mixed together and make smooth and even film surface. The surface roughness of the diamond films deposited by under the condition of CO/H2 and CH4/H2 concentration ratio of 15.3% and 1.5% were 1.86nm and 3.7 nm, respectively, and the diamond/Si(100) interface was uniform resistivity of the films deposited by CO/H2 concentration ratio of 15.3% are obtained 5.3, 1$\times$10-9 A/cm, 1 MV/cm2, and 7.2$\times$106 $\Omega$cm, respectively. In the case of the films deposited by CH4/H2 resistivity are 5.8, 1$\times$10-9 A/cm, 1 MV/cm, and 8.5$\times$106 $\Omega$cm, respectively. In this study, it is known that the diamond films deposited by using CO/H2 gas mixture as a carbon source are better thane these of CH4/H2 one.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.233-233
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• 2006

• Proceedings of the KIEE Conference
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• 1989.11a
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• pp.149-150
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• 1989

Diamond thin films were synthesised from the mixed gases of $CH_4$ and $H_2$ on silicon substrate by R.F plasma CVD and films deposited were investigated by SEM. XRD and Raman spectroscope. From these result, cubo-octahedral diamond particles were synthesised under the following condition: methane concentration. 1.0vol% ; pressure of reactor, 0.3torr ; R.F power, 500W ; reaction time, 20hr.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.6
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• pp.145-151
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• 1996

In sawing operation of cubic zirconia, the performance of diamond cutter blade is very dependent on the blade variables. This investigation presents experimental results which show the effects of the blade variables such as concentration, grain size of diamond, types of diamond abrasives, and bond materials on the behavior of the blades. Based on the experimental results an optimum blade condition for the sawing of cubic zirconia was recommended.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1995.04b
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• pp.69-74
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• 1995

A theoretical analysis is presented on the mechanics of diamond blade sawing. Experimental results are also presented, which show the effects of cutting variables such as cutting speed, feed speed, cutting area, and concentration of deamond blade on the cutting forces. The analytical results aggreed well with experimental ones.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.1
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• pp.84-90
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• 1996

A theoretical analysis is presented on the mechanics of diamond blade sawing. The normal and tangential components of cutting force are calculated. Experimental results are also presented, which show the effects of cutting variables such as cutting speed, feed speed, cutting area, and concentration of diamond blade on the cutting forces. The experimental results are found to be in good agreement with those predicted by the analytical calculation.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.1309-1310
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• 2006

High-purity and super-hard nano-polycrystalline diamond has been successfully synthesized by direct conversion from high-purity graphite under static pressures above 15 GPa and temperatures above $2300^{\circ}C$. This paper describes research findings on the formation mechanism of nano-structure and on the contributing factor leading to high hardness.