• Title/Summary/Keyword: residual Si

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Fabrication of SiC/SiC Composites by Reaction Sintering Process (반응소결법에 의한 SiC/SiC 복합재료의 제조)

  • Lee, S.P.;Yoon, H.K.;Kohyama, A.
    • Proceedings of the KSME Conference
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    • 2001.11a
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    • pp.27-31
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    • 2001
  • Hi-Nicalon SiC fiber reinforced SiC composites (SiC/SiC) have been fabricated by the reaction sintering process. Braided Hi-Nicalon SiC fiber with double interphases of BN and SiC was used in this composite system. The microstructures and the mechanical properties of reaction sintered SiC/SiC composites were investigated through means of electron microscopies (SEM, TEM, EDS) and bending tests. The matrix morphology of reaction sintered SiC/SiC composites was composed of the SiC phases that the composition of the silicon and the carbon is different. The TEM analysis showed that the residual silicon and the unreacted carbon were finely distributed in the matrix region of reaction sintered SiC/SiC composites. Reaction sintered SiC/SiC composites also represented proper flexural strength and fracture energy, accompanying the noncatastrophic failure behavior.

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$\beta$-SiC Formation Mechanisms in Si Melt-C-SiC System (용융 Si-C-SiC계에서 $\beta$-SiC 생성기구)

  • 서기식;박상환;송휴섭
    • Journal of the Korean Ceramic Society
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    • v.36 no.6
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    • pp.655-661
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    • 1999
  • ${\beta}$-SiC formation mechanism in Si melt-C-SiC system with varying in size of carbon source was investigated. A continuous reaction sintering process using Si melt infiltration method was adopted to control the reaction sintering time effectively. It was found that ${\beta}$-SiC formation mechanism in Si melt-C-SiC system was directly affected by the size of carbon source. In the Si melt-C-SiC system with large carbon source ${\beta}$-SiC formation mechanism could be divided into two stages depending on the reaction sintering time: in early stage of reaction sintering carbon dissolution in Si melt and precipitation of ${\beta}$-SiC was occurred preferentially and then SIC nucleation and growth was controlled by diffusion of carbon throughy the ${\beta}$-SiC layer formed on graphite particle. Furthmore a dissolution rate of graphite particles in Si melt could be accelerated by the infiltration of Si melt through basal plane of graphite crystalline.

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A Study on the Dielectric Characteristics and Microstructure of $Si_3N_4$ Metal-Insulator-Metal Capacitors ($Si_3N_4$를 이용한 금속-유전체-금속 구조 커패시터의 유전 특성 및 미세구조 연구)

  • 서동우;이승윤;강진영
    • Journal of the Korean Vacuum Society
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    • v.9 no.2
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    • pp.162-166
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    • 2000
  • High quality $Si_3N_4$ metal-insulator-metal (MIM) capacitors were realized by plasma enhanced chemical vapor deposition (PECVD). Titanium nitride (TiN) adapted as a diffusion barrier reduced the interfacial reaction between $Si_3N_4$ dielectric layer and aluminum metal electrode showing neither hillock nor observable precipitate along the interface. The capacitance and the current-voltage characteristics of the MIM capacitors showed that the minimum thickness of $Si_3N_4$ layer should be limited to 500 $\AA$ under the present process, below which most of the capacitors were electrically shorted resulting in the devastation of on-wafer yield. According to the transmission electron microscopy (TEM) on the cross-sectional microstructure of the capacitors, the dielectric breakdown was caused by slit-like voids formed at the interface between TiN and $Si_3N_4$ layers when the thickness of $Si_3N_4$ layer was less than 500 $\AA$. Based on the calculation of thermally-induced residual stress, the formation of voids was understood from the mechanistic point of view.

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Control of Residual Stress in Diamond Film Fabricated by Hot Filament CVD (열 필라멘트 CVD법에 의해서 제작한 다이아몬드 막의 잔류응력제어)

  • 최시경;정대영;최한메
    • Journal of the Korean Ceramic Society
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    • v.32 no.7
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    • pp.793-798
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    • 1995
  • The relaxation of the intrinsic stresses in the diamond films fabricated by the hot filament CVD was studied, and it was confirmed that the tensile intrinsic stresses in the films could be controlled without any degradation in the quality of the diamond films. The tensile intrinsic stresses in the films decreased from 2.97 to 1.42 GPa when the substrate thickness increased from 1 to 10mm. This result showed that the residual stress was affected by the substrate thickness as well as by the interaction between grains. Applying of +50 V between the W filament and the Si substrate during deposition, the tensile intrinsic stress in the film deposited at 0 V was decreased from 2.40 GPa to 0.71 GPa. Such large decrease in the tensile intrinsic stress was due to $\beta$-SiC which acted as a buffer layer for the stress relaxation. However, the application of the large voltage above +200V resulted in the change of quality of the diamond film, and nearly had no effect on relaxation in the tensile intrinsic stress.

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The relationship between minority carrier life time and structural defects in silicon ingot grown with single seed

  • Lee, A-Young;Kim, Young-Kwan
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.25 no.1
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    • pp.13-19
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    • 2015
  • Among the various possible factors affecting the Minority Carrier Life Time (MCLT) of the mc-Si crystal, dislocations formed during the cooling period after solidification were found to be a major element. It was confirmed that other defects such as grain boundary or twin boundary were not determinative defects affecting the MCLT because most of these defects seemed to be formed during the solidification period. With a measurement of total thickness variation (TTV) and bow of the silicon wafers, it was found that residual stress remaining in the mc-Si crystal might be another major factor affecting the MCLT. Thus, it is expected that better quality of mc-Si can be grown when the cooling process right after solidification is carried out as slow as possible.

A Simulation for Indentifying Influence of The VVT Effect on The SI Engine Performance Using WAVE (WAVE 를 이용한 VVT 효과가 SI 엔진성능에 미치는 영향에 관한 시뮬레이션)

  • Lim, Ock-Taeck;Kim, Dae-Ho;Dutta, Diganta;Tsogtjargal, G.
    • Proceedings of the KSME Conference
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    • 2008.11b
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    • pp.3032-3037
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    • 2008
  • Variable Valve Timing (VVT) system can be used to improve fuel economy, performance and emissions. This study is identified the effect of VVT in terms of wide open throttle torque, Residual gas fraction, volume efficiency. Engine cycle simulations are performed on 2.0L DOHC in-line 4-cylinder SI engine by using WAVE of Ricardo. Results of the simulations had good agreement with WOT torque experimental data, and helped to predict the tendency of performance as the valve timings change. WOT torque was higher when intake valves were closed early for low rpm and late for high rpm.

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Fabrication of Reaction Sintered SiC Materials by Complex Slurry with Nano Size Particles (나노입자 혼합 복합슬러리를 이용한 반응소결 SiC 재료의 제조)

  • Lee Sang-Pill
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.29 no.3 s.234
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    • pp.425-431
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    • 2005
  • The efficiency of complex slurry preparation route for developing the high performance SiC matrix of $RS-SiC_{f}/SiC$ composites has been investigated. The green bodies for RS-SiC materials prior to the infiltration of molten silicon were prepared with various C/SiC complex slurries, which associated with both the sizes of starting SiC particles and the blending conditions of starting SiC and C particles. The characterization of Rs-SiC materials was examined by means of SEM, EDS and three point bending test. Based on the mechanical property-microstructure correlation, the process optimization is also discussed. The flexural strength of Rs-SiC materials greatly depended on the content of residual Si. The decrease of starting SiC particle size in the C/SiC complex slurry was effective for improving the flexural strength of RS-SiC materials.

The Study on Removal of Residual Aluminum in Raw Water (상수원수 중 잔류알루미늄 제거에 관한 연구 (황토와 R-Calmont를 이용하여))

  • 이지헌;김환범;안길원;박찬오;김익산;이종현;박혜영;박송인
    • Journal of environmental and Sanitary engineering
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    • v.13 no.1
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    • pp.57-68
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    • 1998
  • This study was surveyed to examine the removable ability of residual aluminum with the coagulants(LAS, PAC) and the auxiliary coagulants(Loess, R-calmont) on raw water. The leaching test of the auxiliary coagulant showed that the loess contained a lot of Al, Fe and Mn. On the reverse, the R-calmont was a little. Most of the loess were composed of $SiO_{2}$ 53.25%, $Al_{2}O_{3}$ 29.28%, $Fe_{2}O_{3}$ 10.73% and Si/Al ratio was 3.08. In using both LAS vs. loess and PAC vs. loess as the coagulated material, the removal of residual aluminum was the highest as 96.3%, 96.6% respectively, and that of the residual turbidity was 95.0% when PAC vs. R-calmont was dosed 0.2mg/L. Also, loess showed better than R-calmont in the removable efficiency of aluminum and turbidity. When the setting time of auxiliary coagulant was input ar the same time with coagulant, the removal aluminum was the highest as 93.3% to 96.6%.

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CHARACTERIZATION OF MONOLITHIC RS-SiC AND RS-$SiC_f/SiC$ COMPOSITE MATERIALS (반응소결 SiC 재료와 $SiC_f/SiC$ 복합재료의 특성)

  • Jin, Joon-Ok;Lee, Sang-Pill;Lee, Jin-Kyung;Yoon, Han-Ki;Khoyama, Akira
    • Proceedings of the KSME Conference
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    • 2003.04a
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    • pp.376-380
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    • 2003
  • The microstructure and the mechanical properties of RS-SiC and RS-$SiC_f/SiC$ materials have been investigated in conjunction with the content of residual silicon and porosity. The mechanical properties of RS-SiC materials suffered from the thermal exposure were also examined. RS-SiC based materials bave been fabricated using the complex matrix slurry with different composition ratios of SiC and C panicles. The characterization of RS-SiC based materials was investigated by means of SEM, EDS ~d three point bending test. Based on the mechanical property-microstructure correlation, the high temperature applicability of RS-SiC based materials was discussed.

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$M\"{o}ssbsuer$ Effect Study of Nanocrystalline $Fe_{73.5}Cu_{1}Nb_{3}Si_{16.5}B_{6}$ Alloy (초미세결정립 $Fe_{73.5}Cu_{1}Nb_{3}Si_{16.5}B_{6}$ 합금의 뫼스바우어 효과 연구)

  • 김재경;신영남;양재석
    • Journal of the Korean Magnetics Society
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    • v.5 no.5
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    • pp.864-873
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    • 1995
  • Amorphous $Fe_{73.5}Cu_{1}Nb_{3}Si_{16.5}B_{6}$ ribbons were annealed for different time at $500^{\circ}C$ and $552^{\circ}C$, just before and after the exothermic reaction in DSC curve. The development of nanocrystalline phase was investigated by means of $M\"{o}ssbsuer$ spectroscopy. The crystalline phase consists mainly of $DO_{3}Fe-Si$. Though slight in amount (5%), another ferromagnetic phase which could be presumed $t-Fe_{3}B$ was detected Si content of $DO_{3}Fe-Si$, Si/(Fe+Si), was 0.218 under the heat treatment at $500^{\circ}C$ for 60 min and 0.222 at $552^{\circ}C$ for 10 min. Since then both of those values decreased with time until 120 min and finally these two values remained constant at 0.210. The variation in Si content with annealing time results in the variation in the hyperfine field and the isomer shift. The increase in the mean hyperfine fields and the decrease in the mean isomer shifts of Fe-Si are caused by the increase in Si content. The volume fractions of residual amorphous phase rapidly decrease during the early stage of annealing and come nearer to saturation after 120 min both at $500^{\circ}C$ and $552^{\circ}C$. The decrease in the mean hyperfine field of residual amorphous. in spite of slight changes in the volume fractions of Fe-Si and of residual amorphous after 120 min. is caused by the increase in the content of Nb and B in residual amorphous phase. The saturated volume fraction of the crystalline phase was 81% for $500^{\circ}C$ (180 min) and 77% for $552^{\circ}C$ (960 min), different from expectation.

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