• Title/Summary/Keyword: silicon carbide (SiC)

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Crystal growth of 3C-SiC on Si(100) Wafers (Si(100)기판상에 3C-SiC결정성장)

  • Chung, Yun-Sik;Chung, Gwiy-Sang;Nishino, Shigehiro
    • Proceedings of the KIEE Conference
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    • 2002.07c
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    • pp.1593-1595
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    • 2002
  • Single crystal 3C-SiC(cubic silicon carbide) thin-films were deposited on Si(100) wafers up to a thickness of 4.3 ${\mu}m$ by APCVD method using HMDS(hexamethyildisilane) at $1350^{\circ}C$. The HMDS flow rate was 0.5 sccm and the carrier gas flow rate was 2.5 slm. The HMDS flow rate was important to get a mirror-like crystal surface. The growth rate of the 3C-SiC films was 4.3 ${\mu}m/hr$. The 3C-SiC epitaxial films grown on Si(100) were characterized by XRD, AFM, RHEED, XPS and raman scattering, respectively. The 3C-SiC distinct phonons of TO(transverse optical) near 796 $cm^{-1}$ and LO(longitudinal optical) near $974{\pm}1cm^{-1}$ were recorded by raman scattering measurement. The hetero-epitaxially grown films were identified as the single crystal 3C-SiC phase by XRD spectra($2{\theta}=41.5^{\circ}$).

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Effect of Additive Amount on Microstructure and Fracture Toughness of SiC-TiC Composites

  • Min-Jin Kim;Young-Wook Kim;Wonjoong Kim;Hun-Jin Lim;Duk-Ho Cho
    • The Korean Journal of Ceramics
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    • v.6 no.2
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    • pp.91-95
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    • 2000
  • Powder mixtures of $\beta$-SiC-TiC in a weight ratio of 2:1 containing 5-20 wt% additives ($Al_2O_3$-$Y_2O_3$) were liquid-phase sintered at $1830^{\circ}C$ for 1h by hot-pressing and subsequently annealed at $1950^{\circ}C$ for 6h to enhance grain growth. The annealed specimens revealed a microstructure of \"in situ-toughened composite\" as a result of the $\beta$longrightarrow$\alpha$ phase transformation of SiC during annealing. The increase of the content of additives accelerated the growth of elongated $\alpha$-SiC grains with higher aspect ratio and improved fracture toughness. The fracture toughness of SiC-TiC composite containing 20 wt% additive was 6.2 MPa.$m^{1/2}$.2}$.

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Effect of Deposition Parameters on the Property of Silicon Carbide Layer in Coated Particle Nuclear Fuels (피복입자핵연료에서 증착조건이 탄화규소층의 특성에 미치는 영향)

  • Kim, Yeon-Ku;Kim, Weon-Ju;Yeo, SungHwan;Cho, Moon Sung
    • Journal of Powder Materials
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    • v.23 no.5
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    • pp.384-390
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    • 2016
  • Tri-isotropic (TRISO) coatings on zirconia surrogate beads are deposited using a fluidized-bed vapor deposition (FB-CVD) method. The silicon carbide layer is particularly important among the coated layers because it acts as a miniature pressure vessel and a diffusion barrier to gaseous and metallic fission products in the TRISO-coated particles. In this study, we obtain a nearly stoichiometric composition in the SiC layer coated at $1400^{\circ}C$, $1500^{\circ}C$, and $1400^{\circ}C$ with 20 vol.% methyltrichlorosilane (MTS), However, the composition of the SiC layer coated at $1300-1350^{\circ}C$ shows a difference from the stoichiometric ratio (1:1). The density decreases remarkably with decreasing SiC deposition temperature because of the nanosized pores. The high density of the SiC layer (${\geq}3.19g/cm^2$) easily obtained at $1500^{\circ}C$ and $1400^{\circ}C$ with 20 vol.% MTS did not change at an annealing temperature of $1900^{\circ}C$, simulating the reactor operating temperature. The evaluation of the mechanical properties is limited because of the inaccurate values of hardness and Young's modulus measured by the nano-indentation method.

Characteristics of high-temperature single-crystalline 3C-SiC piezoresistive pressure sensors (고온 단결정 3C-SiC 압저항 압력센서 특성)

  • Thach, Phan Duy;Chung, Gwiy-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2008.11a
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    • pp.274-274
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    • 2008
  • This paper describes on the fabrication and characteristics of a 3C-SiC (Silicon Carbide) micro pressure sensor for harsh environment applications. The implemented micro pressure sensor used 3C-SiC thin-films heteroepitaxially grown on SOI (Si-on-insulator) structures. This sensor takes advantages of the good mechanical properties of Si as diaphragms fabricated by D-RIE technology and temperature properties of 3C-SiC piezoresistors. The fabricated pressure sensors were tasted at temperature up to $250^{\circ}C$ and indicated a sensitivity of 0.46 mV/V*bar at room temperature and 0.28 mV/V*bar at $250^{\circ}C$. The fabricated 3C-SiC/SOI pressure sensor presents a high-sensitivity and excellent temperature stability.

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Fabrication of SiCOI Structures Using SDB and Etch-back Technology for MEMS Applications (SDB와 etch-back 기술에 의한 MEMS용 SiCOI 구조 제조)

  • Jung, Su-Yong;Woo, Hyung-Soon;Chung, Gwiy-Sang
    • Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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    • 2003.07b
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    • pp.830-833
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    • 2003
  • This paper describes the fabrication and characteristics of 3C-SiCOI sotctures by SDB and etch-back technology for high-temperature MEMS applications. In this work, insulator layers were formed on a heteroepitaxial 3C-SiC film grown on a Si(001) wafer by thermal wet oxidation and PECVD process, successively. The pre-bonding of two polished PECVD oxide layers made the surface activation in HF and bonded under applied pressure. The wafer bonding characteristics were evaluated by the effect of HF concentration used in the surface treatment on the roughness of the oxide and pre-bonding strength. Hydrophilic character of the oxidized 3C-SiC film surface was investigated by ATR-FTIR. The strength of the bond was measured by tensile strengthmeter. The bonded interface was also analyzed by SEM. The properties of fabricated 3C-SiCOI structures using etch-back technology in TMAH solution were analyzed by XRD and SEM. These results indicate that the 3C-SiCOI structure will offers significant advantages in the high-temperature MEMS applications.

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Point defects and grain boundary effects on tensile strength of 3C-SiC studied by molecular dynamics simulations

  • Li, Yingying;Li, Yan;Xiao, Wei
    • Nuclear Engineering and Technology
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    • v.51 no.3
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    • pp.769-775
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    • 2019
  • The tensile strength of irradiated 3C-SiC, SiC with artificial point defects, SiC with symmetric tilt grain boundaries (GBs), irradiated SiC with GBs are investigated using molecular dynamics simulations at 300 K. For an irradiated SiC sample, the tensile strength decreases with the increase of irradiation dose. The Young's modulus decreases with the increase of irradiation dose which agrees well with experiment and simulation data. For artificial point defects, the designed point defects dramatically decrease the tensile strength of SiC at low concentration. Among the point defects studied in this work, the vacancies drop the strength the most seriously. SiC symmetric tilt GBs decrease the tensile strength of pure SiC. Under irradiated condition, the tensile strengths of all SiC samples with grain boundaries decrease and converge to certain value because the structures become amorphous and the grain boundaries disappear after high dose irradiation.

Study on the effect of silicon content on matrix of hypo-eutectic Cr alloyed cast iron (아공정(亞共晶)Cr 주철(鑄鐵)의 기지조직(基地組織)에 미치는 Si의 영향(影響))

  • Kim, Sug-Won;Lee, Oh-Yeon;Kim, Dong-Keon
    • Journal of Korea Foundry Society
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    • v.4 no.2
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    • pp.96-101
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    • 1984
  • The morphologies of eutectic cell formed during solidification affect on the mechanical properties in high Cr cast iron. In order to investigate the influence of Si on the structure, five kinds of specimen containing 16.42% Cr with varying amount of Si (0.51%, 1.17%, 2.22%, 2.71%, 3.56%) were poured into shell mould preheated $330^{\circ}C$ at $1510^{\circ}C$. The effect of Si on matrix in hypo-eutctic Cr cast iron (2.48% C, 16.42%) were studied through its mechanical tests and observation of microstructure using of metallurgical microscope, EPMA, SEM and Image analyzer systematically. The results obtained from the above studies are as follows: 1. Because of ${\Delta}T$ decreasing with increasing Si content, the morpologies of colony change into uniform bar-type carbide from plate-type ones, moreover eutectic colony size (Ew) becomes narrow and spacing of carbide wider. 2. As Si content increases, the amount of carbides also increases and most of Cr were dissolved in carbides while Si in matrix. 3. The hardness, tensile strength and wear resistance were increasing while impact value decreased with increasing Si content. 4. In fracture section, small amount of dimple pattern was observed in less than 1.17% Si but more than 2.22% Si river pattern was presented.

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Additive Effects on Sintering of Si/SiC Mixtures (Si/SiC 혼합물의 소결특성에 미치는 첨가제의 영향)

  • Kim, Soo Ryong;Kwon, Woo Teck;Kim, Younghee;Kim, Jong Il;Lee, Yoon Joo;Lee, Hyun Jae;Oh, Sea Cheon
    • Korean Journal of Materials Research
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    • v.22 no.12
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    • pp.701-705
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    • 2012
  • The effects of clay, aluminum hydroxide, and carbon powder on the sintering of a Si/SiC mixture from photovoltaic silicon-wafer production were investigated. Sintering temperature was fixed at $1,350^{\circ}C$ and the sintered bodies were characterized by SEM and XRD to analyze the microstructure and to measure the apparent porosity, absorptivity, and apparent density. The XRD peak intensity of SiC in the sintered body was increased by adding 5% carbon to the Si/SiC mixture. From this result, it is confirmed that Si in the Si/SiC mixture had reacted with the added carbon. Addition of aluminum hydroxide decreased the cristobalite phase and increased the stable mullite phase. The measurement of the physical properties indicates that adding carbon to the Si/SiC mixture enables us to obtain a dense sintered body that has high apparent density and low absorptivity. The sintered body produced from the Si/SiC mixture with aluminum hydroxide and carbon powder as sintering additives can be applied to diesel particulate filters or to heat storage materials, etc., since it possesses high thermal conductivity, and anticorrosion and antioxidation properties.

Tribological Properties of Hot Pressed $SiC/Si_3N_4$ Composites (가압소결 $SiC/Si_3N_4$ 복합체의 마찰마모특성)

  • Baik, Yong-Hyuck;Choi, Woong;Park, Yong-Kap
    • Journal of the Korean Ceramic Society
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    • v.36 no.10
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    • pp.1102-1107
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    • 1999
  • SiC-Si3N4 composites were prepared by mixing $\alpha$-Si3N4 powder to $\alpha$-SiC powder in the range of 10 to 30 vol% with 10vol% interval. 6wg% Al2O3 and 6wt% Y2O3 were respectively added as sintering aids. Hot pressing was performed at 1,80$0^{\circ}C$ for 1 hour with 25 MPa pressure. In the case of adding 20vol% of $\alpha$-Si3N4 powder the relative density to theoretical value and the flexural strength were 99.1% and 34,420 MPa respectively and the worn amount was 2.09$\times$10-3 mm2 which were the highest values in the all range of he composition. Although the composite containig 10 vol% of $\alpha$-Si3N4 powder showed the highest fracture toughness(KIC) of 4.65MN/m3/2 the reduction of the wear resistance in this composite is likely to be affected by the homogeneity and the uniformity of the grain coalescence and growth during the sintering process.

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Growth and Characterization of a-Si :H and a-SiC:H Thin Films Grown by RF-PECVD

  • Kim, Y.T.;Suh, S.J.;Yoon, D.H.;Park, M.G.;Choi, W.S.;Kim, M.C.;Boo, J.-H.;Hong, B.;Jang, G.E.;Oh, M.H.
    • Journal of Surface Science and Engineering
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    • v.34 no.5
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    • pp.503-509
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    • 2001
  • Thin films of hydrogenated amorphous silicon (a-Si : H) and hydrogenated amorphous silicon carbide (a-SiC:H) of different compositions were deposited on Si(100) wafer and glass by RF plasma-enhanced chemical vapor deposition (RF-PECVD). In the present work, we have investigated the effects of the RF power on the properties, such as optical band gap, transmittance and crystallinity. The Raman data show that the a-Si:H material consists of an amorphous and crystalline phase for the co-presence of two peaks centered at 480 and $520 cm^{-1}$ . The UV-VIS data suggested that the optical energy band gap ($E_{g}$ ) is not changed effectively with RF power and the obtained $E_{g}$(1.80eV) of the $\mu$c-Si:H thin film has almost the same value of a-Si:H thin film (1.75eV), indicating that the crystallity of hydrogenated amorphous silicon thin film can mainly not affected to their optical properties. However, the experimental results have shown that$ E_{g}$ of the a-SiC:H thin films changed little on the annealing temperature while $E_{g}$ increased with the RF power. The Raman spectrum of the a-SiC:H thin films annealed at high temperatures showed that graphitization of carbon clusters and microcrystalline silicon occurs.

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