• Title/Summary/Keyword: NiMo

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Study on the effect of soldering methods on the characteristics of the Ni-Cr alloy (납착 방법이 치과용 금속의 성상(性狀)에 미치는 영향에 관한 연구)

  • Kim, Chul-Hyung;Song, Young-Gyun;Lee, Jong-Hyuk
    • The Journal of Korean Academy of Prosthodontics
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    • v.50 no.1
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    • pp.53-60
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    • 2012
  • Purpose: The purpose of this study was to compare Ni-Cr alloy property of gas-oxygen torch soldering and infrared welding using optical microscope and Electron Probe Micro Analyzer (EPMA). Materials and methods: Ni-Cr alloys were casted for specimens. Specimens had 3.0 mm diameter, 30.0 mm length and were divided into two groups. Each group had 4 specimens. One group was for gas-oxygen torch soldering and the other was infrared welding. Specimens were cut with low-speed disc and soldered each other with gas-oxygen torch and infrared machine. After soldering and polishing, specimens were observed at 3 points (soldering point, 5 mm distance point, 10 mm distance point) with optical microscope and analyzed 3 points (soldering point, 5 mm distance point, 10 mm distance point with EPMA. Results: The results of this study were as follows: 1. The observation of gas-oxygen torch soldering at 10 mm distance point under the optical microscope was not founded any specific surface properties, but some crack lines were observed at 5 mm distance and soldering point. 2. There were no crack lines were founded at the observation of infrared welding at 10 mm distance and 5 mm distance points under the optical microscope. However, at the 5 mm distance, the surface was not smooth enough compared with at 10 mm distance point. Some crack lines were observed at the welding point as well. 3. In the EPMA analysis of the gas-oxygen torch soldering, the component of Ni was increased by 4.5%, Cr was increased by 7.5% than that of the Ni-Cr alloy at the 10.0 mm distance. At the 5 mm distance, the component of Ni was decreased by 6.1%, Mo was increased by 9.0% than that of the Ni-Cr alloy but Cr was equally shown at the 5.0 mm distance. Only Ni was shown at the soldering point. 4. In the EPMA analysis of the infrared welding, the component of Ni was increased by 9.1%, Cr was increased by 0.4% than that of the Ni-Cr alloy but Al was equal at the 10.0 mm distance. At the 5 mm distance, the component of Ni was increased by 4.7%, Cr was increased by 4.7% and Al was increased by 0.1% than that of the Ni-Cr alloy. At the welding point, the component of Ni was increased by 8.8%, Cr was increased by 8.2% than that of the Ni-Cr alloy. Conclusion: From these results, at the 5 mm distance from the soldering point, the surface of the infrared welding was more smoother than that of the gas-oxygen torch soldering. On the EPMA analysis, the component of the specimens with infrared welding was more similar than that of the gas-oxygen torch soldering compared with the component of the Ni-Cr alloy.

Electrochemical Properties of Zr0.8Ti0.2Mn0.4V0.6Ni1-xFex Alloy Electrodes (Zr0.8Ti0.2Mn0.4V0.6Ni1-xFex 합금 전극의 전기화학적 특성)

  • Song, MyoungYoup;Kwon, IkHyun;Lee, DongSub
    • Transactions of the Korean hydrogen and new energy society
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    • v.13 no.3
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    • pp.181-189
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    • 2002
  • A series of multicomponent $Zr_{0.8}Ti_{0.2}Mn_{0.4}V_{0.6}Ni_{1-x}Fe_{x}$ (x=0.00, 0.08, 0.15, 0.22, and 0.30) alloys are prepared and their oystal structure and P-C-T curves are examined. The electrochemical properties of these allqys such as activation conditions, discharge capacity, cycling performance are also investigated. $Zr_{0.8}Ti_{0.2}Mn_{0.4}V_{0.6}Ni_{1-x}Fe_{x}$ (x=0.00, 0.08, 0.15, 0.22 and 0.30) have the C14 Laves phase hexagonal structure. The electrode was activated by the hot-charging treatment. The best activation conditions were the current density 120 mA/g and the hot-charging time 12h at $80^{\circ}C$ in the case of the alloy with x=0.00. The discharge capacity increased rapidly until the fourth cycle and then decreased. The discharge capacity increased again from the 13th cycle, arriving at 234 mAh/g at the 50th cycle. The discharge capacily just after activation decreases with the increase in the amount of the substituted Fe but the cycling performance is improved. The discharge capacity after activation of the alloy with x=0.00 is 157 mAh/g at the current density 120 mA/g. $Zr_{0.8}Ti_{0.2}Mn_{0.4}V_{0.6}Ni_{0.85}Fe_{0.15}$ is a good composition with a medium quantity of discharge capacities and a good cycling performance. The ICP analysis of the electrolyte for these electrodes after 50 charge-discharge cycles shows that the concentrations of V and Zr are relatively high. Another series of multicomponent $Zr_{0.8}Ti_{0.2}Mn_{0.4}V_{0.6}Ni_{0.85}M_{0.15}$ (M = Fe, Co, Cu, Mo and Al) alloys are prepared. They also have the C14 Laves phase hexagonal structure. The alloys with M = Co and Fe have relatively larger hydrogen storage capacities. The discharge capacities just after activation are relatively large in the case of the alloys with M = Al and Cu. They are 212 and 170 mAh/g, respectivety, at the current density 120mA/g. The $Zr_{0.8}Ti_{0.2}Mn_{0.4}V_{0.6}Ni_{0.85}Co_{0.15}$ alloy is the best one with a relatively large discharge capacity and a good cycling performance.

Effect of friction from differing vertical bracket placement on the force and moment of NiTi wires (브라켓의 수직적 변위에 따른 마찰이 NiTi wire의 힘과 모멘트에 미치는 영향)

  • Park, Jea-Beom;Yoo, Ji-A;Mo, Sung-Seo;Choi, Kwang-Cheol;Kim, Yoon-Ji;Han, Seong-Ho;Kook, Yoon-Ah
    • The korean journal of orthodontics
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    • v.41 no.5
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    • pp.337-345
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    • 2011
  • Objective: The purpose of this study was to evaluate the effect of force and moment produced by Nickel-titanium wires of different sizes at activation and deactivation according to differing vertical bracket displacement. Methods: Superelastic NiTi wires of 3 different sizes (0.014", 0.016", and 0.016" ${\times}$ 0.022") were tied with elastomeric or 0.009-inch stainless steel ligations in a twin-bracket, 0.018-inch slot. A testing machine recorded the effects of simulated activation of 5 distances from 1 to 5 mm and deactivation of 5 distances from 4 to 0 mm, in increments of 1 mm. Results: Frictional force increased the wire stiffness during loading. Ligation of 0.014-inch NiTi wire with O-ring resulted in a significant increase in the stiffness. On application of orthodontic force for 5 mm of vertical displacement of teeth, the effective displacement in the case of the 0.014", 0.016", and 0.016" ${\times}$ 0.022" NiTi wires was 2 mm, 3 mm, and 4 mm, respectively. Conclusions: Our results showed that movement of teeth with large vertical displacement was ineffective because of excessive friction. This finding might contribute to the understanding of the force system required for effective teeth movement and thereby facilitate the application of the appropriate light wire for leveling and alignment.

Manufactures of dental casting Co-Cr-Mo based alloys in addition to Sn, Cu and analysis of infrared thermal image for melting process of its alloys (Sn 및 Cu를 첨가한 치과 주조용 Co-Cr-Mo계 합금제조 및 용해과정 분석)

  • Kang, Hoo-Won;Park, Young-Sik;Hwang, In;Lee, Chang-Ho;Heo, Yong;Won, Yong-Gwan
    • Journal of Technologic Dentistry
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    • v.36 no.3
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    • pp.141-147
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    • 2014
  • Purpose: Dental casting #Gr I (Co-25Cr-5Mo-3Sn-1Mn-1Si), #Gr II (Co-25Cr-5Mo-5Cu-1Mn -1Si) and #Gr III (Co-25Cr-5Mo-3Sn-5Cu-1Mn-1Si) master alloys of granule type were manufactured the same as manufacturing processes for dental casting Ni-Cr and Co-Cr-Mo based alloys of ingot type. These alloys were analyzed melting processes with heating time of high frequency induction centrifugal casting machine using infrared thermal image analyzer. Methods: These alloys were manufactured such as; alloy design, the first master alloy manufatured using vacuum arc casting machine, melting metal setting in crucible, melting in VIM, pouring in the mold of bar type, cutting the gate and runner bar and polishing. These alloys were put about 30g/charge in the ceramic crucible of high frequency induction centrifugal casting machine and heat, Infrared thermal image analyzer indicated alloys in the crucible were set and operated. Results: The melting temperatures of these alloys measuring infrared thermal image analyzer were decreased in comparison with remanium$^{(R)}$ GM 800+, vera PDI$^{TM}$, Biosil$^{(R)}$ f, WISIL$^{(R)}$ M type V, Ticonium 2000 alloys of ingot type and vera PDS$^{TM}$(Aabadent, USA), Regalloy alloys of shot type. Conclusion: Co-Cr-Mo based alloy in addition to Sn(#Gr I alloy) were decreased the melting temperature with heating time of high frequency induction centrifugal casting machine using infrared thermal image analyzer.

The Evaluation of Trace Minerals Levels of Pasture Soils and Forages in Jeju (제주지역 목장 토양 및 조사료 자원의 미량광물질 함량 평가)

  • Lee, Chong-Eon;Park, Myung-Hee;Park, Nam-Keon;Park, Hyung-Soo;Oh, Woon-Yong
    • Journal of The Korean Society of Grassland and Forage Science
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    • v.27 no.1
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    • pp.29-36
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    • 2007
  • A study was conducted to determine the trace minerals (Cu, Fe, Cd, Zn, Mo, Se, Mn, Cr, Co, Ni) levels in pasture soils and forages collected in Jeju area. Chemical characteristics and total or soluble trace minerals levels in 187 pasture soil samples (76 very dark brown and 111 black soils) were measured. Total trace minerals contents in hay samples of 60 Italian ryegrass, alfalfa and mixture grasses each were assessed. The pasture soils of Jeju were characterized to have low pH (5.1) and to contain low levels of available $P_2O_5$ (20.5 mg/kg) and exchangeable Ca, Mg, K, Na (2.6, 0.9, 0.5, 0.2 cmol+/kg, respectively) when comparing to upland soils of Jeju or Korean mainland. All trace elements in total or soluble analysis of pasture soils were detected, and there was a big difference between total and soluble levels. The pasture soils tended to have the higher total Fe, Mn, Ni and Zn contents. Cr in all forages was not detected, but other trace minerals levels showed normal range. The hay samples of Italian ryegrass and mixture grasses produced in Jeju tended to contain higher Mn (105 vs 23 mg/kg) and lower Mo (2.7 vs 4.9 mg/kg) than those of alfalfa hay imported from USA. Results show that trace minerals of pasture soils and forages in Jeju seem to be not deficient, indicating that supplementation of some trace minerals are not always necessary in diets for grazing animals and should be done after careful evaluation of diets with regard to concentrations and biological availability of essential elements.

Direct Methanation of Syngas over Activated Charcoal Supported Molybdenum Catalyst (활성탄 담지 몰리브덴 촉매를 이용한 합성가스 직접 메탄화 반응)

  • KIM, SEONG-SOO;LEE, SEUNG-JAE;PARK, SUNG-YOUL;KIM, JIN-GUL
    • Transactions of the Korean hydrogen and new energy society
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    • v.31 no.5
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    • pp.419-428
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    • 2020
  • The kinetics of direct methanation over activated charcoal-supported molybdenum catalyst at 30 bar was studied in a cylindrical fixed-bed reactor. When the temperature was not higher than 400℃, the CO conversion increased with increasing temperature according to the Arrhenius law of reaction kinetics. While XRD and Raman analysis showed that Mo was present as Mo oxides after reduction or methanation, TEM and XPS analysis showed that Mo2C was formed after methanation depending on the loading of Mo precursor. When the temperature was as high as 500℃, the CO conversion was dependent not only on the Arrhenius law but also on the catalyzed reaction by nanoparticles, which came off from the reactor and thermocouple by metal dusting. These nanoparticles were made of Ni, Fe, Cr and alloy, and attributed to the formation of carbon deposit on the wall of the reactor and on the surface of the thermocouple. The carbon deposit consisted of amorphous and disordered carbon filaments.

Design of a Rectangular Loop Array Antenna for Beam Scanning (빔 조향이 가능한 직사각형 루프 배열 안테나의 설계)

  • Koo, Han-Ni;Han, In-Hee;Kim, Dong-Seok;Kim, Chan-Hong;Park, Dong-Chul
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.8
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    • pp.922-929
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    • 2007
  • In this paper, a rectangular loop array antenna for beam scanning is designed. A program using RWG MoM(Rao Wilton Glisson Method of Moment) is developed for SEP(Scan Element Pattern) theoretically. Simulation results obtained by using a commercial software tool, MWS are compared with the MoM results to confirm the validity of the program. Also these results are compared with the measured ones for the case of an $8{\times}5$ subarray. The fabricated $8{\times}5$ subarray showed a flat gain characteristic in the elevation scan range of ${\pm}45^{\circ}$ in the E-plane.

Evaluations of Si based ternary anode materials by using RF/DC magnetron sputtering for lithium ion batteries

  • Hwang, Chang-Muk;Park, Jong-Wan
    • Proceedings of the Korean Vacuum Society Conference
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    • 2010.08a
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    • pp.302-303
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    • 2010
  • Generally, the high energy lithium ion batteries depend intimately on the high capacity of electrode materials. For anode materials, the capacity of commercial graphite is unlike to increase much further due to its lower theoretical capacity of 372 mAhg-1. To improve upon graphite-based negative electrode materials for Li-ion rechargeable batteries, alternative anode materials with higher capacity are needed. Therefore, some metal anodes with high theoretic capacity, such as Si, Sn, Ge, Al, and Sb have been studied extensively. This work focuses on ternary Si-M1-M2 composite system, where M1 is Ge that alloys with Li, which has good cyclability and high specific capacity and M2 is Mo that does not alloy with Li. The Si shows the highest gravimetric capacity (up to 4000mAhg-1 for Li21Si5). Although Si is the most promising of the next generation anodes, it undergoes a large volume change during lithium insertion and extraction. It results in pulverization of the Si and loss of electrical contact between the Si and the current collector during the lithiation and delithiation. Thus, its capacity fades rapidly during cycling. Si thin film is more resistant to fracture than bulk Si because the film is firmly attached to the substrate. Thus, Si film could achieve good cycleability as well as high capacity. To improve the cycle performance of Si, Suzuki et al. prepared two components active (Si)-active(Sn, like Ge) elements film by vacuum deposition, where Sn particles dispersed homogeneously in the Si matrix. This film showed excellent rate capability than pure Si thin film. In this work, second element, Ge shows also high capacity (about 2500mAhg-1 for Li21Ge5) and has good cyclability although it undergoes a large volume change likewise Si. But only Ge does not use the anode due to its costs. Therefore, the electrode should be consisted of moderately Ge contents. Third element, Mo is an element that does not alloys with Li such as Co, Cr, Fe, Mn, Ni, V, Zr. In our previous research work, we have fabricated Si-Mo (active-inactive elements) composite negative electrodes by using RF/DC magnetron sputtering method. The electrodes showed excellent cycle characteristics. The Mo-silicide (inert matrix) dispersed homogeneously in the Si matrix and prevents the active material from aggregating. However, the thicker film than $3\;{\mu}m$ with high Mo contents showed poor cycling performance, which was attributed to the internal stress related to thickness. In order to deal with the large volume expansion of Si anode, great efforts were paid on material design. One of the effective ways is to find suitably three-elements (Si-Ge-Mo) contents. In this study, the Si based composites of 45~65 Si at.% and 23~43 Ge at.%, and 12~32 Mo at.% are evaluated the electrochemical characteristics and cycle performances as an anode. Results from six different compositions of Si-Ge-Mo are presented compared to only the Si and Ge negative electrodes.

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Evaluation of Mechanical Property for Pb-free Solder/Ni Plate Joints with Artificial Aging Time (인공시효시간에 따른 Ni 기판 Pb-free 솔더접합부의 기계적 물성평가)

  • Park, So Young;Yang, Sung Mo;Yu, Hyo Sun
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.39 no.5
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    • pp.467-471
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    • 2015
  • Thus far, solders used in electronics remain lead-based. Pb-free solutions in electronic components and systems are receiving increased attention in the semiconductor and electronics industries. Pb-free materials currently in used are Sn-37Pb, Sn-4Ag and Sn-4Ag-0.5Cu/Ni plate joints. In this study, solder alloys were used at high temperatures for artificial aging processing that was performed at $150^{\circ}C$ for 0hr, 100hr, 200hr, 400hr, 600hr and 1000hr. The SP test was conducted at $30^{\circ}C$ and $50^{\circ}C$. As a result, the maximum shear strength of all the specimens decreased with the increase in artificial aging time and temperature of the SP test. In addition, Pb-free solders showed higher total fracture energy compared with Sn-37Pb at high temperatures. The mechanical properties of Sn-4Ag-0.5Cu solder/Ni plate joints remained in excellent conditions in electronic parking systems at high temperatures.

Flip Chip Solder Joint Reliability of Sn-3.5Ag Solder Using Ultrasonic Bonding - Study of the interface between Si-wafer and Sn-3.5Ag solder (초음파를 이용한 Sn-3.5Ag 플립칩 접합부의 신뢰성 평가 - Si웨이퍼와 Sn-3.5Ag 솔더의 접합 계면 특성 연구)

  • Kim Jung-Mo;Kim Sook-Hwan;Jung Jae-Pil
    • Journal of the Microelectronics and Packaging Society
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    • v.13 no.1 s.38
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    • pp.23-29
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    • 2006
  • Ultrasonic soldering of Si-wafer to FR-4 PCB at ambient temperature was investigated. The UBM of Si-substrate was Cu/ Ni/ Al from top to bottom with thickness of $0.4{\mu}m,\;0.4{\mu}m$, and $0.3{\mu}m$ respectively. The pad on FR-4 PCB comprised of Au/ Ni/ Cu from top to bottom with thickness of $0.05{\mu}m,\;5{\mu}m$, and $18{\mu}m$ respectively. Sn-3.5wt%Ag foil rolled to $100{\mu}m$ was used for solder. The ultrasonic soldering time was varied from 0.5 s to 3.0 s and the ultrasonic power was 1,400 W. The experimental results show that a reliable bond by ultrasonic soldering at ambient temperature was obtained. The shear strength increased with soldering time up to a maximum of 65 N at 2.5 s. The strength decreased to 34 N at 3.0 s because cracks were generated along the intermetallic compound between Si-wafer and Sn-3.5wt%Ag solder. The Intermetallic compound produced by ultrasonic soldering between the Si-wafer and the solder was $(Cu,Ni)_{6}Sn_{5}$.

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