• Title/Summary/Keyword: boron effect

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Effect of carbon and boron addition on sintering behavior and mechanical properties of hot-pressed SiC (카본 및 보론 첨가가 탄화규소 열간 가압 소결거동 및 기계적 특성에 미치는 영향)

  • Ahn, Jong-Pil;Chae, Jae-Hong;Kim, Kyoung-Hun;Park, Joo-Seok;Kim, Dae-Gean;Kim, Hyoung-Sun
    • Journal of the Korean Crystal Growth and Crystal Technology
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    • v.18 no.1
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    • pp.15-21
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    • 2008
  • SiC has an excellent resistance to oxidation and corrosion, high temperature strength and good thermal conductivity. However, it is difficult to density because of its highly covalent bonding characteristics. Hot-press sintering process was applied to fabricate fully densified SiC ceramics with carbon and boron addition as a sintering additive. The addition of carbon improved the mechanical properties of SiC because it could induce a fine and homogeneous microstructure by the suppression of abnormal growth of SiC grain. Also, the addition of carbon could control the phase transformation of SiC. The phase transformation of 6H to 4H increased with sintering temperature but the addition of carbon decreased that kind of phase transformation.

Analysis and comparison of initial performance degradation for single crystalline silicon solar cell under open and short circuit (단결정 태양전지의 단락 및 개방 시 노광에 의한 초기 출력저하 비교 분석)

  • Jung, Tae-Hee;Kim, Tae-Bum;Shin, Jun-Oh;Yoon, Na-Ri;Woo, Sung-Cheol;Kang, Gi-Hwan;Ahn, Hyung-Keun;Han, Deuk-Young
    • Journal of the Korean Solar Energy Society
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    • v.30 no.6
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    • pp.16-21
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    • 2010
  • It is well-known that Boron-doped Cz Si solar cells suffer light-induced degradation due to boron-oxygen defect which is responsible of a reduction in lifetime and hence efficiency. In this paper, we assume that PV solar cell has been connected with variable load to account the real operating condition and it shows different light-induced degradation of Si solar cell. To evaluate the effect of light-induced degradation for solar cell with various load, Single crystalline solar cells are connected with open and short circuits during light exposure. Isc-Voc curve evaluate light induced degradation of solar cells and the reason is explained as a change for serial resistance. From the results, Electrical characteristics of solar cells show better performance under short circuit conditions, after light exposure.

Effect of Hot-stamping Heat Treatment on the Microstructure of Al-Segregated Zone in TWB Laser Joints of Al-Si-coated Boron Steel and Zn-coated DP Steel (Al-Si 도금된 보론강과 Zn 도금된 DP강 TWB 레이저 용접부내의 Al-편석부 미세조직에 미치는 핫스탬핑 열처리의 영향)

  • Jung, Byung Hun;Kong, Jong Pan;Kang, Chung Yun
    • Korean Journal of Metals and Materials
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    • v.50 no.6
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    • pp.455-462
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    • 2012
  • Al-Si coated boron steel and Zn coated DP steel plates were laser-welded to manufacture a Tailor Welded Blank (TWB) for a car body frame. Hot-stamping heat treatment ($900^{\circ}C$, 5 min) was applied to the TWB weld, and the microstructural change and transformation mechanism were investigated in the Al-rich area near the bond line of the Al-Si coated steel side. There was Al-rich area with a single phase, $Fe_3(Al,Si)$, which was transformed to ${\alpha}-Fe$ (Ferrite) after the heat treatment. It could be explained that the $Fe_3(Al,Si)$ phase was transformed to ${\alpha}-Fe$ during heat treatment at $900^{\circ}C$ for 5 min and the resultant ${\alpha}-Fe$ phase was not transformed by rapid cooling. Before the heat treatment, the microstructures around the $Fe_3(Al,Si)$ phase consisted of martensite, bainite and ${\alpha}-Fe$ while they were transformed to martensite and ${\delta}-Fe$ after the heat treatment. Due to the heat treatment, Al was diffused to the $Fe_3(Al,Si)$ and this resulted in an increase of Al content to 0.7 wt% around the Al-rich area. If the weld was held at $900^{\circ}C$ for 5 min it was transformed to a mixture of austenite (${\gamma}$) and ${\delta}-Fe$, and only ${\gamma}$ was transformed to the martensite by water cooling while the ${\delta}-Fe$ was remained unchanged.

Effects of Pinching and Application of Mg, B and Zn on Growth and Yield of Sesame (적심과 Mg, B 및 Zn 시용이 참깨 생육 및 수량에 미치는 영향)

  • 정병관
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.35 no.4
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    • pp.304-308
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    • 1990
  • This study was conducted to increase the yield of sesame on the undeveloped upland by pinching and application of minor nutrients which were magnesium. boron and zinc. The effect of phinching to yield at 20 days after germination was 17%. and pinching effect at 50 days after germination with minor nutrients was 46% compared to non-treatments. These effect were considered as increasing the number of capsule per plant. number of node per main stem. and 1,000 grains weight. Simultaneously, the nutrients (Mg. B and Zn) were recognized to promote remarkably the yield.

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Three-dimensional Modeling of Transient Enhanced Diffusion (과도 증속 확산(TED)의 3차원 모델링)

  • 이제희;원태영
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.35D no.6
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    • pp.37-45
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    • 1998
  • In this paper, we report the first three-dimensional simulation result of the transient enhanced diffusion(TED) of dopants in the ion-implanted silicon by employing our 3D semiconductor process simulator, INPROS system. In order to simulate three-dimensional TED redistribution of dopants in silicon, the dopant distributions after the ion implantation was calculated by Monte Carlo(MC) method, followed by finite element(FE) numerical solver for thermal annealing. Excellent agreement between the simulated 3D profile and the SIMS data has been obtained for ion-implanted arsenic and phosphorus after annealing the boron marker layer at 75$0^{\circ}C$ for 2 hours. Our three-dimensional TED simulation could successfully explain the reverse short channel effect(RSCE) by taking the 3D point defect distribution into account. A coupled TED simulation and device simulation allows reverse short channel effect on threshold to be accurately predicted.

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Evaluation of energy release rate of composites laminated with finite element method

  • Achache, Habib;Boutabout, Benali;Benzerdjeb, Abdelouahab;Ouinas, Djamel
    • Structural Engineering and Mechanics
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    • v.55 no.1
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    • pp.191-204
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    • 2015
  • Control of the mechanical behavior of composite materials and structures under monotonic and dynamic loads for cracks and damage is a vast and complex area of research. The modeling of the different physical phenomena and behavior characteristics of a composite material during deformation play an important role in the structural design. Our study aims to analyze numerically the energy release rate parameter G of a composite laminated plate (glass or boron / epoxy) cross-ply [$+{\alpha}$, $-{\alpha}$] in the presence of a crack between two circular notches under the effect of several parameters such as fiber orientation ${\alpha}$, the crack orientation ${\beta}$, the orientation ${\gamma}$ of the two considered circular notches and the effect of mechanical properties. Our results show clearly that both notches orientation has more effect on G than the cracks and fibers orientations.

The role of grain boundary modifier in $BaTiO_3$ system for PTCR device ($BaTiO_3$계 PTC 재료에서 입계 modifier의 역할)

  • Lee, Jun-Hyeong;Jo, Sang-Hui
    • Korean Journal of Materials Research
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    • v.3 no.5
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    • pp.553-561
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    • 1993
  • In this study, thr effect of $Bi_2O_3$ and BN addition as grain boundary modifiers on sintering and electrical properties of semiconducting PTCR(Positive Temperature Coefficient of Resistivity) mate rial were analyzed using TMA, XRD and Complex Impedance Spectroscopy method. Bismut.h Ox~de and Boron Nitride were added to Y-doped $BaTiO_3$ respectively. Bismuth sesquioxide up to O.lmol%solubil~ ty limit of $Bi_2O_3$ in Y--$BaTiO_3$ ceramics-retarded densification and grain growth, and further addition mitigated these retardation effects. The resistivity at room temperature increased with increasing amount of $Bi_2O_3$ and thus decreased the PTCR effect, probably due to the $Bi_2O_3$ segregation on the grain boundaries. From the complex ~mpedance pattern, it is known that the grain boundary resisitivity is dominant on the whole resistivity of sample. In the result of applying the defect chemistry, $Bi^{3+} \;and \; Bi^[5+}$ are substituted for Ua and Ti site, respectively. Boron nitride decomposed and formed liquid phase among the $BaTiO_3$ grains. The decomposed com~ ponents made the second phase and existed the tr~ple juntion from the result of EPMA. From the complex impendencc pattern, the gram and grain boundary resistivity were small. The grain size increased with increasing BN contents, and decreased grain boundary resistivity enhanced the PTCR effect.

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Preparation and Opticaa Properties of CuCl Nanocrystallites Dispersed Nonlinear Optical Glass by Sol-Gel Process (솔-젤법에 의한 CuCl 미세결정이 분산된 비선형 광학유리의 제조 및 광특성)

  • 송석표;한원택;김병호
    • Journal of the Korean Ceramic Society
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    • v.34 no.9
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    • pp.941-948
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    • 1997
  • CuCl nanocrystallites dispersed nonlinear optical silica and borosilicate glasses were fabricated by sol-gel process. CuCl powder was dissolved in TEOS(Si(OC2H5)4) and TMB((CH3O)3B), precursors of silica and borosilicate glasses, with ethanol, water and HCl, and precipitated through the heat treatment in the matrix glass. The optical properties of CuCl doped glasses were measured using the spectrophotometer at room temperature and low temperature(77K); Z1, 2 and Z3 exciton peaks from the absorption spectra, were observed at about 370 nm and 380 nm, respectively. The average radius of nanocrystallites, calculated from the blue shift of Z3 excitons, was measured according to annealing temperature and time. The precipitation temperature of CuCl nanocrystallites was decreased when boron was added to silica glass. Increase of annealing temperature and time made average radius of nanocrystallites saturated about 2 nm.

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Modification and adhesion improvement of BN interfacial layers by Post-N+ implantation (질소 이온주입법에 의한 BN 박막의 계면구조 개선 및 밀착력 향상)

  • 변응선;이성훈;이상로;이구현;한승희;이응직;윤재홍
    • Journal of the Korean Vacuum Society
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    • v.8 no.2
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    • pp.157-164
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    • 1999
  • The post ion implantation has been applied to modify early-grown BN layer and improve the adhesion of the BN films. The effect of ion implantation doses on microstructure and interlayer was investigated by FTIR and HRTEM. And the hardness and delamination life time of N+-implanted BN films were measured. With increasing the ion dose up to $5.0\times10^{15}\textrm{atoms/cm}^2$,the change of IR spectrum is observed. At $5.0\times10^{16}\textrm{atoms/cm}^2$, a drastic transition of cubic phase into hexagonal phase is detected. The change of microstructure of early-grown layers by ion implantation is confirmed using HRTEM. Both microhardness and delamination life time of BN films increase with ion dose. The modification model of early-grown BN layers is briefly discussed based on the displacement per atom and excess boron in the BN film induced by ion irradiation.

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The Characteristic and Formation of Ti(B,N) Films on Steel by EA Hot Filament CVD (EA hot filament CVD system을 이용하여 금형공구강에 증착한 Ti(B,N)박막의 합성과 특성에 관하여)

  • Yoon, Jung-H.;Choi, Yong;Choe, Jean-I.
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.61 no.4
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    • pp.585-589
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    • 2012
  • The characteristics of interface layer and the effect of mole fraction of inlet gas mixture($B_2H_6/H_2/N_2/TiCl_4$) on the microstructure of Ti(B,N) films were studied by microwave plasma hot filament CVD process. Ti(B,N) films were deposited on a substrate(STD-61) to develop a high performance of resistance wear coating tool. Ti(B,N) films were obtained at a gas pressure of 1 torr, bias voltage of 300 V and substrate temperature of $480^{\circ}C$ in $B_2H_6/H_2/N_2/TiCl_4$gas system. It was found that TiN, $TiB_2$, TiB and hexagonal boron nitride(h-BN) phases exist in thin layer on the STD-61.