• Journal of the Korean institute of surface engineering
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• v.29 no.5
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• pp.540-544
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• 1996

To apply the CVD diamond film to coated tools, it is necessary to make adhesion strength between diamond film and substrate stronger. So adhesion strength of diamond coated WC-Co tools using Microwave Plasma CVD and cutting test of Al-18mass%Si alloy using diamond cutting tools were studied. Diamond coating was carried out using Microwave Plasma CVD apparatus. Reaction gas was used mixture of methane and hydrogen. Substrate temperature were varied from 673K to 1173K by control of microwave output power and reaction pressure. By observation of SEM, grain size became larger and larger as substrate temperature became higher and higher. Also all deposits were covered with clear diamond crystals. XRD results, the deposits were identified to cubic diamond. An analysis using Raman spectroscopy, the deposit synthesized at lower substrate temperature (673K) showed higher quality than deposit synthesized at higher substrate temperature (1173K). As a result of scratch adhesion strength test, from 873K to 1173K adhesion strength decreased by rising of substrate temperature. The deposit synthesized at 873K showed best adhesion strength. In the cutting test of Al-18mass%Si alloy using diamond coated tools and the surface machinability of Al-Si works turned with diamond coating tools which synthesized at 873K presented uniform roughness. Cutting performance of Al-18mass%Si alloys using diamond coated WC-Co tools related to the adhesion strength.

• Journal of the Korean Society for Heat Treatment
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• v.34 no.2
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• pp.75-80
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• 2021

The crystal grains of polycrystalline diamond vary depending on deposition conditions and growth thickness. The diamond thin film deposited by the CVD method has a very rough growth surface. On average, the surface roughness of a diamond thin film deposited by CVD is in the range of 1-100 um. However, the high surface roughness of diamond is unsuitable for application in industrial applications, so the surface roughness must be lowered. As the surface roughness decreases, the scattering of incident light is reduced, the heat conduction is improved, the mechanical surface friction coefficient can be lowered, and the transmittance can also be improved. In addition, diamond-coated cutting tools have the advantage of enabling ultra-precise machining. In this study, the surface roughness of diamond was improved by thermal diffusion reaction between diamond carbon atoms and ferrous metals at high temperature for diamond thin films deposited by MPCVD.

• 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.

• The Korean Journal of Ceramics
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• v.2 no.4
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• pp.188-192
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• 1996

Diamond based electronic devices promise to exhibit unique properties. In order to realize devices diamond has to be doped to render it electrically conductive. In the present work the doping of diamond and of polycrystalline CVD diamond films are reviewd with particular emphasis to ion-implantation doping and to attempts to dope diamond by in-diffusion of the dopants. The quest for finding ways to obtain n-type conductivity in diamond will be critically examined.

• Journal of the Semiconductor & Display Technology
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• v.3 no.3
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• pp.45-50
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• 2004

Highly oriented diamond (HOD) films in polycrystalline can be grown on the (100) silicon substrate by microwave plasma CVD. Bias enhanced nucleation (BEN) method was adopted for highly oriented diamond deposition with high nucleation density and uniformity. The substrate was biased up to -250[Vdc] and bias time required for forming a diamond film was varied up to 25 minutes. Diamond was deposited by using $\textrm{CH}_4$/CO and $H_2$ mixture gases by microwave plasma CVD. Nucleation density and degree of orientation of the diamond films were studied by SEM. Thermal conductivity of the diamond films was ∼5.27[W/cm.K] measured by $3\omega$ method.

• Journal of Radiation Protection and Research
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• v.43 no.4
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• pp.131-136
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• 2018

Background: We investigated the current characteristics of a thin-film Ag electrode on a chemical vapor deposition (CVD) diamond. The CVD diamond is widely recognized as a radiation detection material because of its high tolerance against high radiation, stable response to various dose rates, and good sensitivity. Additionally, thin-film Ag has been widely used as an electrode with high electrical conductivity. Materials and Methods: Considering these properties, the thin-film Ag electrode was deposited onto CVD diamonds with varied deposition thicknesses (${\fallingdotseq}50/98/152/257nm$); subsequently, the surface thickness, surface roughness, leakage current, and photo-current were characterized. Results and Discussion: The leakage current was found to be very low, and the photo-current output signal was observed as stable for a deposited film thickness of 98 nm; at this thickness, a uniform and constant surface roughness of the deposited thin-film Ag electrode were obtained. Conclusion: We found that a CVD diamond radiation detector with a thin-film Ag electrode deposition thickness close to 100 nm exhibited minimal leakage current and yielded a highly stable output signal.

• Composites Research
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• v.24 no.4
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• pp.23-28
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• 2011

Recently CFRP laminate joints process by bolts and nets are developed rapidly in aircraft industries. However, there are serious drawback during jointing process. Many hole processes are needed for the manufacturing and structural applications using composite materials. Generally, very durable polycrystalline crystalline diamond (PCD) drill has been used for the CFRP hole process. However, due to the expensive price and slow process speed, chemical vapor deposition (CVD) diamond drill has been used increasingly which are relatively-low durability but easily-adjustable process speed via drill shape change and price is much lower. In this study, the comparison of hole process between PCD and CVD diamond coated drills was done. First of all, CFRP hole processbility was evaluated using the equations of hole processing conditions (feed amount per blade, feed speed). The comparison on thermal damage occurring from the CFRP specimen was also studied during drilling process. Empirical equation was made from the temperature photo profile being taken during hole process by infrared thermal camera. In addition, hole processability was compared by checking hole inside condition upon chip exhausting state for two drills. Generally, although the PCD can exhibit better hole processability, hole processing speed of CVD diamond drill exhibited faster than PCD case.

• The Korean Journal of Ceramics
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• v.2 no.4
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• pp.184-187
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• 1996

Diamod nucleation by mw assisted CVD was examined various conditions namely, (1) diamond nucleation on variour substrate materials, such as Si, cubic BN, pyrolytic BN and AIN, (2) AST(Activated species transport) method which promote nucleation of diamond on single crystal and polycrystalline alumina substrate was developed. (3) Effect of bias enhancement of nucleation on single crystalline Si was examined, and finally (4) DST (Double step treatment) method was developed to enhance diamond nucleation on Ni. In this method, we separated carbon diffusing process into Ni, carbon precipitating process from the inside of Ni and diamond precipitation process.

• Proceedings of the KIEE Conference
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• 2001.07c
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• pp.1533-1536
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• 2001

To grow the diamond films by using RF-MW two step process, at first, diamond seeds were deposited on silicon substrate by RF plasma CVD, and then a diamond layer grown by MW plasma CVD on the seeds. The grain-size of diamond films deposited by using RF-MW two step process was smaller and denser and also, crystallity of diamond film was better than those of the MW plasma CVD process. The deposited diamond films were analyzed by SEM(scanning electron microscophy), XRD (x-ray diffraction), and Raman spectroscopy.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.50 no.2
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• pp.49-56
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• 2001

Diamond thin films have been deposited on the silicon substrate by inductively coupled radio frequency plasma enhanced chemical vapor deposition system. The morphological features of thin films depending on methane concentration and deposition time have been studied by scanning electron microscopy and Raman spectroscopy. The diamond particles deposited uniformly on silicon substrate($10{\times}10[mm^2]$) at the pressure of 1[torr], a methane concentration of 1[%], a hydrogen flow rate of 60[sccm], a substrate temperature of $840\{sim}870[^{\circ}C]$, an input power of 1[kw], and a deposition time of 1[hour]. With increasing deposition time, the diamond particles grew, and than about 3 hours have passed, the graphitic phase carbon thin film with "cauliflower-like" morphology deposited on the diamond thin films.