• Title/Summary/Keyword: CVD-diamond

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Dependence of the Diamond Coating Adhesion on the Microstructure of WC-Co Substrates (WC-Co계 미세조직에 따른 CVD 다이아몬드 코팅막의 접착력 변화)

  • Lee, Dong-Beum;Chae, Ki-Woong
    • Journal of the Korean Ceramic Society
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    • v.41 no.10 s.269
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    • pp.728-734
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    • 2004
  • The effect of microstructure of WC-Co substrates which have different WC grain sizes from submicron to 5 $\mu$m on the diamond-substrate adhesion strength was investigated. The substrates were pre-treated by two methods : chemical etching with Murakami's solution and subsequently with $H_2SO_4$, and thermal heat-treatment. The adhesion strength was estimated by degree of peeling after Rockwell indentation. Diamond films of 20 $\mu$m thickness deposited on the heat-treated substrates showed an excellent adhesion strength at the load of 100 kg, which ascribed to the large and elongated WC grains. However, the cutting edge of insert was deformed after heat treatment and the surface morphology of heat treated substrate strongly affected on the surface roughness of the deposited diamond films. On the contrary, the diamond film of 10 $\mu$m in thickness on the chemically etched substrates of average WC grain size over 2 $\mu$m showed good adhesion strength enough not to peel-off under a load of 60 kg. Especially, the substrate of average WC grain size over 5 $\mu$m exhibited much improved reliability of adhesion comparing with the substrate of average grain size under 2 $\mu$m. No substrate deformation was observed in this case after the chemical etching, which is more advantageous and more practical in terms of precious machining than the heat treatment case.

The Characteristics of Diamond-like Carbon Films Deposited by Low Frequency(60Hz) Plasma CVD at Room Temperature for Optical lens (광학렌즈를 위한 저주파(60Hz) 플라즈마 CVD로 실온에서 제작한 다이아몬드성 탄소 박막의 특성)

  • Kang, Sung Soo;Lee, Won Jin;Sung, Duk Yong
    • Journal of Korean Ophthalmic Optics Society
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    • v.1 no.1
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    • pp.23-28
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    • 1996
  • Hydrogenated amorphous carbon films were fabricated by low frequency(60Hz) Plasma enhanced Chemical vapor deposition(LF-PECVD) at room temperature. The LF_PECVD has a couple of advantages as follows: cheap, and the employment of low power density makes the damage of samples small. The a-C:H films deposited in this work were highly transparent(99%), highly resistance(109-1011${\Omega}$-cm), and very uniform. The samples were deposited by the decomposition of CH4 and H2 mixing gas in the pressure rate range of 1% to 30%. The deposition rates, optical gap, and hydrogen contents are increased with CH4 contents.

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Optical Properties of Diamond Like Carbon Films Deposited by Plasma Enhanced CVD (rf PECVD법으로 증착된 DLC film의 광학적 성질)

  • Kim, Moon-Hyup;Song, Jae-Jin;Kim, Seong-Jin
    • Korean Journal of Materials Research
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    • v.11 no.7
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    • pp.550-555
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    • 2001
  • A diamond-like carbon(DLC) films were deposited on the borosilicate glass substrate by radio frequency plasma enhanced chemical deposition(rf-PECVD). The $methane(CH_4)-hydrogen(H_2)$ gas mixture was used as precursor gas. The morphologies, the structure and the optical properties of the DLC films were investigated by SEM, Raman and UV spectrometer. The deposition rate was slightly increased with the hydrogen concentration in the gas mixture and it maintained constant at over 25 sccm of the gas flow rate. The optical band gap calculated by UV spectra decreased with increase of deposition time and DC self bias, but that were not effected by hydrogen content. Most effective parameter on the transmittance of film was bias voltage, especially in the range of ultra violet and visible light.

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Development of Precision Drilling Machine for the Instrumentation of Nuclear Fuels (핵연료계장을 위한 정밀 드릴링장치 개발)

  • Hong, Jintae;Jeong, Hwang-Young;Ahn, Sung-Ho;Joung, Chang-Young
    • Journal of the Korean Society for Precision Engineering
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    • v.30 no.2
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    • pp.223-230
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    • 2013
  • When a new nuclear fuel is developed, an irradiation test needs to be carried out in the research reactor to analyze the performance of the new nuclear fuel. In order to check the performance of a nuclear fuel during the irradiation test in the test loop of a research reactor, sensors need to be attached in and out of the fuel rod and connect them with instrumentation cables to the measuring device located outside of the reactor pool. In particular, to check the temporary temperature change at the center of a nuclear fuel during the irradiation test, a thermocouple should be instrumented at the center of the fuel rod. Therefore, a hole needs to be made at the center of fuel pellet to put in the thermocouple. However, because the hardness and the density of a sintered $UO_2$ pellet are very high, it is difficult to make a small fine hole on a sintered $UO_2$ pellet using a simple drilling machine even though we use a diamond drill bit made by electro deposition. In this study, an automated drilling machine using a CVD diamond drill has been developed to make a fine hole in a fuel pellet without changing tools or breakage of workpiece. A sintered alumina ($Al_2O_3$) block which has a higher hardness than a sintered $UO_2$ pellet is used as a test specimen. Then, it is verified that a precise hole can be drilled off without breakage of the drill bit in a short time.

Structure and mechanical properties of nitrogenated diamond-like carbon films deposited by RF-PACVD (RF 플라즈마 CVD에 의해 합성된 질소 함유 다이아몬드성 카본필름의 구조 및 기계적 특성)

  • 이광렬;은광용
    • Journal of the Korean Vacuum Society
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    • v.6 no.2
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    • pp.151-158
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    • 1997
  • Nitrogen incorporated diamond-like carbon films were deposited by r.f. glow discharge of mixtures of benzene and ammonia gases. Mechanical properties, composition and atomic bond structure were investigated when the fraction of ammonia increases from 0 to 0.79 and the negative self bias voltage of cathode from 100 to 900 V. Both the residual compressive stress and the hardness decrease from 1.7 to 1.0 GPa and from 2750Kgf/$\textrm{mm}^2$ to 1700Kgf/$\textrm{mm}^2$, respectively. In addition to hydrogen, triply bonded nitrogens also play a role of teminal sites of the three dimensional atomic bond network. By considering the hydrogen concentration and the nitrogen bond characteristics, it can be shown that the mechanical properties of the films are determined by the content of three dimensional inter-links of $sp^2$ clusters. Although the mechanical properties are affected by the nitrogen addition, its depedence on the negative bias voltage is qualitatively identical to that of pure diamond-like carbon films.

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Computer Simulation of Temperature Parameter for Diamond Formation by using Hot- Filament Chemical Vapor Deposition (온도 매개 변수의 컴퓨터 시뮬레이션을 통한 HF-CVD를 이용한 다이아몬드 증착 거동 분석)

  • Song, Chang-Won;Lee, Yong-Hui;Choe, Su-Seok;Hwang, Nong-Mun;Kim, Gwang-Ho
    • Proceedings of the Korean Institute of Surface Engineering Conference
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    • 2018.06a
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    • pp.54-54
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    • 2018
  • To optimize the deposition parameters of diamond films, the temperature, pressure, and distance between the filament and the susceptor need to be considered. However, it is difficult to precisely measure and predict the filament and susceptor temperature in relation to the applied power in the hot filament chemical vapor deposition (HFCVD) system. In this study the temperature distribution inside the system was numerically calculated for the applied powers of 12, 14, 16 and 18 kW. The applied power needed to achieve the appropriate temperature at a constant pressure and other conditions was deduced, and applied to actual experimental depositions. The numerical simulation was conducted using the commercial computational fluent dynamics software, ANSYS-FLUENT. To account for radiative heat-transfer in the HFCVD reactor, the discrete ordinate (DO) model was used. The temperatures of the filament surface and the susceptor at different power levels were predicted to be 2512 ~ 2802 K, and 1076 ~ 1198 K, respectively. Based on the numerical calculations, experiments were performed. The simulated temperatures for the filament surface were in good agreement with experimental temperatures measured using a 2-color pyrometer. The results showed that the highest deposition rate and the lowest deposition of non-diamond was obtained at a power of 16 kW.

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Characterization of Diamond-like Carbon Films on Si-Wafer Deposited by DC Plasma CVD.

  • Ju Tack Han;Jong-Gi Jee;Eun-joo Shin;Dongho Kim
    • Journal of the Korean Vacuum Society
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    • v.3 no.4
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    • pp.434-441
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    • 1994
  • 메탄과 수소 혼합가스로 직류 플라즈마 화학 증착법을 이용하여 방전전류 반응압력 메탄농도 및 피착체의 온도를 변화시키면서 다이아몬드 유산탄소 박막(DLCF)을 Si(111)-웨이퍼 위에 합성하였다. 주 사전자 현미경(SEM)과 레이져 Raman 스펙트로포토메터로 확인된 양질의 DLCF를 얻은 조건은 방전전 류 반응 압력, 메탄농도 그리고 피착체의 온도가 각각 480mA, 32 Torr, 1.0 vol% 및 85$0^{\circ}C$ 였다. 이 DLCF는 대부분 sp3 탄소결합으로 된 구형의 알갱이들로 구성되어 있고 그굴절률은 2.2로 천연다이아몬 드와 비슷한 값을 가지고 있다. 또한 DLCF 성장에서 수소피복이 매우 중요한 것으로 밝혀졌다.

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Theory of Charged Clusters as New Understanding of Thin Film Growth

  • Hwang, Nong-Moon;Kim, Doh-Yeon
    • 한국정보디스플레이학회:학술대회논문집
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    • 2002.08a
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    • pp.147-152
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    • 2002
  • A new theory of thin film growth was suggested, where charged clusters of nanometer size are generated in the gas phase and are a major flux for thin films. The existence of these hypothetical clusters was experimentally confirmed in the diamond and silicon CVD processes as well as in metal evaporation. These results imply new insights as to the microstructure control of thin films. Based on this new understanding, the low temperature deposition of crystalline and amorphous silicon can be approached systematically.

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Alignment property change in DLC alignment layer containing various hydrogen concentration

  • Kim, Jong-Bok;Kim, Kyung-Chan;Ahn, Han-Jin;Hwang, Byung-Har;Baik, Hong-Koo
    • 한국정보디스플레이학회:학술대회논문집
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    • 2005.07a
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    • pp.378-380
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    • 2005
  • Diamond like carbon (DLC) films are known that they show homogeneous alignment property when they are irradiated by Ar ion beam. The DLC films in most of studies were deposited by CVD and contain large mount of hydrogen. In order to identity the hydrogen effect on alignment property, DLC films is deposited by RF magnetron sputter using various ratio of Ar and H2 as reactive gas. DLC films are characterized by FT-IR, Raman and contact angle. Alignment property is estimated by measuring pretilt angle.

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APPLICATION OF RADIO-FREQUENCY (RF) THERMAL PLASMA TO FILM FORMATION

  • Terashima, Kazuo;Yoshida, Toyonobu
    • Journal of the Korean institute of surface engineering
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    • v.29 no.5
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    • pp.357-362
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    • 1996
  • Several applications of radio-frequency (RF) thermal plasma to film formation are reviewed. Three types of injection plasma processing (IPP) technique are first introduced for the deposition of materials. Those are thermal plasma chemical vapor deposition (CVD), plasma flash evaporation, and plasma spraying. Radio-frequency (RF) plasma and hybrid (combination of RF and direct current(DC)) plasma are next introduced as promising thermal plasma sources in the IPP technique. Experimental data for three kinds of processing are demonstrated mainly based on our recent researches of depositions of functional materials, such as high temperature semiconductor SiC and diamond, ionic conductor $ZrO_2-Y_2O_3$ and high critical temperature superconductor $YBa_2Cu_3O_7-x$. Special emphasis is given to thermal plasma flash evaporation, in which nanometer-scaled clusters generated in plasma flame play important roles as nanometer-scaled clusters as deposition species. A novel epitaxial growth mechanism from the "hot" clusters namely "hot cluster epitaxy (HCE)" is proposed.)" is proposed.osed.

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