• Title/Summary/Keyword: V2C

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The Solidification Microstructure of X%C-5%Cr-5%V-5%Mo-5%W-5%Co Multi-Component White Cast Iron (X%C-5%Cr-5%V -5%Mo-5%W-5%Co 다합금계백주철의 응고조직에 관한 연구)

  • Yu, Sung-Kon;Yasuhiro Matsubara
    • Korean Journal of Materials Research
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    • v.11 no.6
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    • pp.472-476
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    • 2001
  • Type and three-dimensional morphology of carbides precipitated in the X(X= 1.70, 1.92, 2.21, 2.50, 2.86)%C-5%Cr-5%V-5%Mo-5%W-5%Co multi-component white cast iron were investigated using an optical microscope and SEM. The types of carbides precipitated were MC, M$_2$C and M$_{7}$C$_{3}$. Morphology of the MC carbide took three forms, that it petal-like, nodular and coral-like. MC carbide seemed to change its morphology from petal-like through nodular, and finally to coral-like with an increase in carbon content. M7C carbide was classified into lamellar and plate-like type. The lamellar M$_2$C arbide precipitated in the iron with low molybdenum and tungsten contents, and higher contents of both elements in the iron were needed to form the plate-like M$_2$C carbide. The morphology of M$_{7}$C$_{3}$ was rod-like similar to that observed in high chromium white cast iron. However, cobalt does not affect the type and morphology of precipitated carbides.des.

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Synthesis and Characterization of 2,2'-Biimidazole (2,2'-Biimidazole의 합성 및 구조분석)

  • Collier, Harvest L.;Cho, Il Young
    • Analytical Science and Technology
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    • v.11 no.1
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    • pp.8-12
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    • 1998
  • The 2,2'-Biimidazole was synthesized by the reaction between glycol and ammonium solution. The correct solid structure of 2,2'-biimidazole in this method reported either trans ($C_{2h}$) or cis ($C_{2v}$) form. In this study, the correct structure of 2,2'-biimidazole was analysed by both FTIR and Raman spectroscopy using mutual exclusion properties of them. Also, it was analysed by $^1H$ and $^{13}C$ NMR and computer molecular modeling. The structure of 2,2'-biimidazole found to be trans ($C_{2h}$) than cis ($C_{2v}$) by comparison between FTIR and Raman Spectra. This results agree with computer molecular modeling and x-ray crystallography. This study provide good evidence for identifying structural orientation of the 2,2'-biimidazole containing pyridyl nitrogen.

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High Temperature Oxidation of Ti-6Al-4V, Ti-4Fe, Ti-(1,2)Si Alloys (Ti-6Al-4V, Ti-4Fe, Ti-(1,2)Si합금의 고온산화)

  • 박기범;이동복
    • Journal of Surface Science and Engineering
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    • v.34 no.2
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    • pp.135-141
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    • 2001
  • Arc-melted Ti-6Al-4V, Ti-4Fe and Ti-(1,2) Si alloys were oxidized at 700, 800, 900 and $1000^{\circ}C$ in air. The oxidation resistance of Ti-4Fe was comparable to that of Ti-6Al-4V, while the oxidation resistance of Ti-(1,2) Si was superior to that of Ti-6Al-4V. Ti-2Si displayed the best oxidation resistance among the four alloys, but failed after oxidation at $1000^{\circ}C$ for 17h. The oxide scale formed on Ti-6Al-4V, Ti-4Fe and Ti-(1,2)Si consisted of ($TiO_2$ and a small amount of $Al_2$$O_3$), ($TiO_2$ and a small amount of dissolved iron), and ($TiO_2$ plus a small concentration of amorphous $SiO_2$), respectively. The oxide grains of the surface scale of the four alloys were generally fine and round.

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C-V Characteristics of Cobalt Polycide Gate formed by the SADS(Silicide As Diffusion Source) Method (SADS(Siliide As Diffusion Source)법으로 형성한 코발트 폴리사이트 게이트의 C-V특성)

  • 정연실;배규식
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.13 no.7
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    • pp.557-562
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    • 2000
  • 160nm thick amorphous Si and polycrystalline Si were each deposited on to 10nm thick SiO$_2$, Co monolayer and Co/Ti bilayer were sequentially evaporated to form Co-polycide. Then MOS capacitors were fabricated by BF$_2$ ion-implantation. The characteristics of the fabricated capacitor samples depending upon the drive-in annel conductions were measured to study the effects of thermal stability of CoSi$_2$and dopant redistribution on electrical properties of Co-polycide gates. Results for capacitors using Co/Ti bilayer and drive-in annealed at 80$0^{\circ}C$ for 20~40sec. showed excellent C-V characteristics of gate electrode.

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The Effect of $MnO_2$ Addition on the $V_2O_5/TiO_2$ Catalytic Filters for NO Reduction (NO 환원반응을 위한 $V_2O_5/TiO_2$계 촉매필터의 $MnO_2$ 조촉매 효과)

  • Shin, Hae-Joong;Choi, Jae-Ho;Song, Young-Hwan;Lee, Ju-Young;Jang, Sung-Cheol;Choi, Joo-Hong
    • Proceedings of the SAREK Conference
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    • 2008.11a
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    • pp.363-368
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    • 2008
  • Nitrogen oxides (NO, $NO_2$ and $N_2O$) have been controlled effectively by the SCR catalysts coated on monolith or honeycomb in commercial sites with ammonia as reductant at high temperature range $300{\sim}400^{\circ}C$. However, the catalytic filter has much merit on the point of controlling the particles and nitrogen oxides simultaneously. It will be more advanced-system if the catalytic working temperature is reduced to the normal filtration temperature of under $200^{\circ}C$. This study has focus on the development of the catalytic filter working at the low temperature. So the additive effect of the components such as Pt and Mn (which are known the catalytic component of $V_2O_5/TiO_2$ was investigated. The $V_2O_5-WO_3$ catalytic filter exhibited high activity and selectivity at $250{\sim}320^{\circ}C$ showing more than 95% NO conversion for the treatment of 600 ppm NO at face velocity 2 cm/s. The Pt-$V_2O_5-WO_3$ catalytic filter shifted the optimum working temperature towards the lower temperature ($170{\sim}200^{\circ}C$). And NO conversion was 100% and higher than that of $V_2O_5-WO_3$ catalyst at $250{\sim}320^{\circ}C$. The $MnO_X-V_2O_5-WO_3$ catalytic filter showed the wide temperature range of $220{\sim}330^{\circ}C$ for more than 95% NO conversion. This is a remarkable advantage when considered the $MnO_X$ catalytic filter presents the maximum activity at $150{\sim}250^{\circ}C$ and $V_2O_5-WO_3$ catalytic filter shows the maximum activity at $250{\sim}320^{\circ}C$.

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NOx removal of Mn-Cu-TiO2 and V/TiO2 catalysts for the reaction conditions (반응조건에 대한 Mn-Cu-TiO2촉매와 V/TiO2촉매의 탈질 특성)

  • Jang, Hyun Tae;Cha, Wang Seog
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.17 no.7
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    • pp.713-719
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    • 2016
  • The NOx conversion properties of Mn-Cu-$TiO_2$ and $V_2O_5$/$TiO_2$ catalysts were studied for the selective catalytic reduction (SCR) of NOx with ammonia. The performance of the catalysts was investigated in terms of their $NOx$ conversion activity as a function of the reaction temperature and space velocity. The activity of the Mn-Cu-$TiO_2$ catalyst decreased with increasing reaction temperature and space velocity. However, the activity of the $V_2O_5$/$TiO_2$ catalyst increased with increasing reaction temperature. High activity of the Mn-Cu-$TiO_2$ catalyst was observed at temperatures below $200^{\circ}C$. H2-TPR and XPS analyses were conducted to explain these results. It was found that the activity of the Mn-Cu-$TiO_2$ catalyst was influenced by the thermal shock caused by the change of the initial reaction temperature, whereas the $V_2O_5$/$TiO_2$ catalyst was not affected by the initial reaction temperature. In the case of catalyst C, the $NO_x$ conversion efficiency decreased with increasing space velocity. The decrease in the $NO_x$ conversion efficiency with increasing space velocity was much less for catalyst D than for catalyst C.

Commercial Production for the Hydrogen Generation with Alkaline Electrode Cells (수소 생산을 위한 알칼라인 수전해장치 상용품 제작)

  • KIM, BO YEON;KIM, DONG JIN;KANG, EUN YOUNG;KIM, TAE WAN;SIM, HUI CHAN;LEE, TAECK HONG
    • Journal of Hydrogen and New Energy
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    • v.26 no.3
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    • pp.206-211
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    • 2015
  • For the hydrogen production, Gas Lab and Gnc make alkaline watrer electrolyzer and found optimized condition of experimental parameters of cell material and operating procedures. For the commercial production, we saved electric power consumption and caloric based efficiency with over 70%. Used cell pressures are 10 bar, 30 bar and consumed electricity is $4,000A/m^2$, 4.19 kW ($T=100^{\circ}C$) at 10 bar. Another data is $2,000A/m^2$, 3.92 kW ($T=95^{\circ}C$) at 30 bar. Applied voltage is 1.75 V ($100^{\circ}C$, 10 bar), 1.64 V ($95^{\circ}C$, 10 bar), 1.81 V ($85^{\circ}C$, 30 bar), 1.76 V ($95^{\circ}C$, 30 bar). As cell temperature increase, applied voltage has been decreased and current has been increased. The concentration of KOH solution is 30 weight %.

Thermal Stability and C- V Characteristics of Ni- Polycide Gates (니켈 폴리사이드 게이트의 열적안정성과 C-V 특성)

  • Jeong, Yeon-Sil;Bae, Gyu-Sik
    • Korean Journal of Materials Research
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    • v.11 no.9
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    • pp.776-780
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    • 2001
  • $SiO_2$ and polycrystalline Si layers were sequentially grown on (100) Si. NiSi was formed on this substrate from a 20nm Ni layer or a 20nm Ni/5nm Ti bilayer by rapid thermal annealing (RTA) at $300~500^{\circ}C$ to compare thermal stability. In addition, MOS capacitors were fabricated by depositing a 20nm Ni layer on the Poly-Si/$SiO_2$substrate, RTA at $400^{\circ}C$ to form NiSi, $BF_2$ or As implantation and finally drive- in annealing at $500~800^{\circ}C$ to evaluate electrical characteristics. When annealed at $400^{\circ}C$, NiSi made from both a Ni monolayer and a Ni/Ti bilayer showed excellent thermal stability. But NiSi made from a Ni/Ti bilayer was thermally unstable at $500^{\circ}C$. This was attributed to the formation of insignificantly small amount of NiSi due to suppressed Ni diffusion through the Ti layer. PMOS and NMOS capacitors made by using a Ni monolayer and the SADS(silicide as a dopant source) method showed good C-V characteristics, when drive-in annealed at $500^{\circ}C$ for 20sec., and$ 600^{\circ}C$ for 80sec. respectively.

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Studies on the Immobilization of ${\beta}-Galactosidase$ from Bacillus subtilis (Bacillus subtilis ${\beta}-Galactosidase$의 고정화에 관한 연구)

  • Jang, Gi;Kim, Chang-Ryoul;Lee, Yong-Kyu
    • Korean Journal of Food Science and Technology
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    • v.22 no.4
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    • pp.426-433
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    • 1990
  • The conditions for immobilization of the partially purified ${\beta}-galactosidase$ form Bacillus subtilis HP4 and the properties of the immobilized enzyme have been investigated. The crude enzyme precipitated with cold acetone was purified about 68-fold through DEAE-cellulose and sephadex G-100 chromatography and its recovery was 19.9% The optimal conditions for Immobilization of enzyme were obtained in 2%(w/v) sodium alginate, 15%(v/v) enzyme solution and 2%(w/v) calcium chloride, and also the optimal stirring thme was 2 hours on the above conditions. The optimum temperature and pH values for immobilized enzyme were $55^{\circ}C$ and 6.5, respectively. Its residual activity was show 25% after heat treatment for an hour at $65^{\circ}C$, and found its high stability in pH 6.0 to 8.0. The enzyme activity was not affected b)· EDTA, 2-mercaptoethanol, KCN, protective agents, and other methal ions except Hg ion and Cu ion. The $K_m\;and\;V_{max}$ values of the immobilized enzyme on ONPG were $1.82{\times}10^{-2}M\;and\;3.57{\times}10^{-8}mole/min$, whereas those on lactose were $2.94{\times}10^{-2}M\;and\;1.68{\times}10^{-7} mole/min$, respectively. The remained enzyme activity for the immobilized enzyme was 95%t of original activity after storage of 40 days at $4^{\circ}C$, and when reused for 5 times was 81%. When skim milk(4.8% lactose) and 5% lactose solution were reacted with the immobilized enzyme(250 units/g) of lactose were 51% and 43%, respectively.

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Empennage Design of Solar-Electric Powered High Altitude Long Endurance Unmanned Aerial Vehicle (고고도 장기체공 전기 동력 무인기의 꼬리 날개 설계)

  • Hwang, Seung-Jae;Lee, Yung-Gyo;Kim, Cheol-Wan;Ahn, Seok-Min
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.41 no.9
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    • pp.708-713
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    • 2013
  • KARI is developing a solar-electric powered HALE UAV(EAV-3). For demonstrating the technology, EAV-2H, a down-scaled version of EAV-3, is developed and after EAV-2H's initial flight test, the directional stability and control need to be improved. Thus, the vertical tail and rudder of EAV-2H are redesigned with Advanced Aircraft Analysis(AAA). Size of the rudder is increased from mean chord ratio of rudder to vertical tail, $C_r/C_v(%)=30$ to $C_r/C_v(%)=60$ and size of the vertical tail is reduced 15%. As a result, the directional control to side wind($v_1$) is improved to sideslip angle, ${\beta}(deg)=25^{\circ}$ and $v_1(m/sec)=3.54$. Also, variation of airplane side force coefficient with sideslip angle ($C_{y_{\beta}}$) and variation of airplane side force coefficient with dimensionless rate of change of yaw rate ($C_{y_r}$) are reduced 15% and 22%, respectively to minimize the effect of side wind. The empennage design of EAV-2H is verified with flight tests and applied to design of KARI's solar-electric-powered EAV-3.