• Title/Summary/Keyword: Alloying reaction

검색결과 109건 처리시간 0.025초

기계적 합금화에 의한 Cr-N계 합금의 비정질화 과정 (Amorphization Process of Cr-N Alloy System by Mechanical Alloying)

  • 이충효;이성희;이상진;권영순
    • 한국분말재료학회지
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    • 제10권4호
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    • pp.288-293
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    • 2003
  • Mechanical alloying (MA) by high energy ball mill of Pure chromium Powders was carried out under the nitrogen gas atmosphere. Cr-N amorphous alloy powders have been produced through the solid-gas reaction subjected to MA. The atomic structure during amorphization process was observed by X-ray and neutron diffractions. An advantage of the neutron diffraction technique allows us to observe the local atomic structure surrounding a nitrogen atom. The coordination number of metal atoms around a N atom turns out to be 5.5 atoms. This implies that a nitrogen atom is located at both of centers of the tetrahedron and octahedron formed by metal atoms to stabilize an amorphous Cr-N structure. Also, we have revealed that a Cr-N amorphous alloy may produced from a mixture of pure Cr and Cr nitrides powders by solid-solid reaction during mechanical alloying.

기계적 압금화에 의한 $MoSi_2$-TiC 복합분말의 제조 (Fabrication of $MoSi_2$-TiC Composite Powders by Mechanical Alloying)

  • 윤종열
    • 한국분말재료학회지
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    • 제6권2호
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    • pp.178-185
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    • 1999
  • MoSi$_2$-TiC composite powders were fabricated by in-situ reaction through mechanical alloying. Also the monolithic MoSi$_2$ as well as TiC were synthesiced by mechanical alloying for comparison. An abrupt increase of vial surface temperature was detected due to a sudden reaction between elemental powders during milling. The reaction time for synthesis of composite powders decreased with increasing the content of (Ti+C) powder. It was found that a significant decrease of Ti grain size was observed with increasing the milling time. And the synthesis reaction of MoSi$_2$-TiC composite powders were largely dependent on the reaction between Ti and C powders.

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Conversion-Alloying Anode Materials for Na-ion Batteries: Recent Progress, Challenges, and Perspective for the Future

  • Kim, Joo-Hyung;Kim, Do Kyung
    • 한국세라믹학회지
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    • 제55권4호
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    • pp.307-324
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    • 2018
  • Rechargeable lithium-ion batteries (LIBs) have been rapidly expanding from IT based applications to uses in electric vehicles (EVs), smart grids, and energy storage systems (ESSs), all of which require low cost, high energy density and high power density. The increasing demand for LIBs has resulted in increasing price of the lithium source, which is a major obstacle to wider application. To date, the possible depletion of lithium resources has become relevant, giving rise to the interest in Na-ion batteries (NIBs) as promising alternatives to LIBs. A lot of transition metal compounds based on conversion-alloying reaction have been extensively investigated to meet the requirement for the anodes with high energy density and long life-time. In-depth understanding the electrochemical reaction mechanisms for the transition metal compounds makes it promising negative anode for NIBs and provides feasible strategy for low cost and large-scale energy storage system in the near future.

Mechanical Alloying Method로 제조된 고온수전해용 Ni/YSZ cermet의 제조 및 특성 (Synthesis and Characteristic of Ni/VSZ Cermet for High Temperature Electrolysis Prepared by Mechanical Alloying Method)

  • 채의석;홍현선;추수태
    • 한국수소및신에너지학회논문집
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    • 제16권4호
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    • pp.372-378
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    • 2005
  • Ni/YSZ ($Y_2O_3$-stabilized $ZrO_2$) composite powder for a cathode material in high temperature electrolysis(HTE) was synthesized by a mechanical alloying method with Ni and YSZ powder. Microstructure of the composite and cell thickness for HTE reaction has been analyzed with various techniques of XRD, SEM to investigate effects of fabrication conditions. Employing the composite material, furthermore, the unit cell for HTE has been studied to evolve hydrogen from water. XRD patterns showed that the composites after wet mechanical alloying were composed of respective nano-sized crystalline Ni and YSZ. While ethanol as additive for mechanical alloying increased to $20\;{\mu}m$ of average particle size of the composites, alpha-terpineol effectively decreased to sub-micro size of that. This study has been found out the evolution of hydrogen by HTE reaction employing the fabricated cathode material, showing 1.4 ml/min of $H_2$ generation rate as increasing $20\;{\mu}m$ of cathode thickness.

Mo-25.0at%Si 혼합분말의 기계적 합금화에 미치는 밀링매체 재료의 영향 (Effect of Milling Medium Materials on Mechanical Alloying of Mo-25.0at%Si Powder Mixture)

  • 박상보
    • 한국분말재료학회지
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    • 제5권1호
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    • pp.64-70
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    • 1998
  • Milling media of steel and partially stabilized zirconia(PSZ) were used to produce $Mo_3$Si by mechanical alloying(MA) of Mo-25.0at%Si elemental powder mixture. The effect of milling medium materials on MA of the powder mixture have been investigated by XRD and DTA. The reaction rate and the end-product noticeably depended upon the milling medium material. The formation of $Mo_3$Si and $Mo_5Si_3$phases by PSZ ball-milling took place after 15 hr of MA and was characterized by a slow reaction rate as Mo, Si, $Mo_5Si_3$ and $Mo_3$Si coexisted for a long period of milling time. The formation of a new phase by steel ball-milling, however, did not take Place even after 96 hr of MA. DTA and annealing results showed that $Mo_5Si_3$ and $Mo_3$Si were formed after heating the ball-milled powder specimens to different temperatures. At low temperatures, Mo and Si were transformed into $Mo_5Si_3$. At high temperatures, the formation of $Mo_3$Si can be partially attributed to the reaction, 7Mo+Si+$Mo_5Si_3$-.4$Mo_3$Si . The formation of $Mo_3$Si and Mo5Si3 phases by mechanical alloying of the powder mixture and the relevant reaction rate appeared to depend upon the milling medium material as well as the thermodynamic properties of the end-products.

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알루미늄 합금 용탕/STD61 공구강의 계면 반응층 형성에 미치는 합금원소의 영향 (The Effects of Alloying Elements on the Formation of Interfacial Reaction Layer between Molten Aluminium Alloys and STD61 Tool Steel)

  • 박흥일;박호일
    • 한국주조공학회지
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    • 제25권4호
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    • pp.161-167
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    • 2005
  • The experiment of hot dip interaction tests was carried out in order to study the formation behavior of interfacial reaction layer between as-received STD61 hot work tool steel and a commercial pure aluminum melt, Al-xwt.%Fe(x=0.2, 0.5, 0.8 and 1.1) alloys melt and Al-xwt.%Si(x=1.0, 4.0, 7.0 and 10.0) alloys melt, respectively. The results show that the reaction layer, over 300 ${\mu}m$ in thickness, is easily formed by the dissolution of silicon from as-received tool steel. When the iron content in the aluminum alloy is higher than 1.1 wt.%, the thickness of reaction layer decreases below 180 ${\mu}m$ by preventing iron dissolution from the tool steel. The silicon dissolved from tool steel acts as a strong promoter on the formation of reaction layer, but the alloyed silicon in molten aluminum alloys acts as an inhibitor on the formation of reaction layer.

고급강 제조 반응 모델의 검토 : Part. 1. Coupled Reaction 기반 시뮬레이션 모델 (A Review of Kinetic Model for Production of Highgrade Steel : Part. 1. Simulation Model Based on Coupled Reaction)

  • 김정인;김선중
    • 자원리싸이클링
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    • 제30권1호
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    • pp.3-13
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    • 2021
  • 고급강은 소비자가 원하는 적절한 조성을 갖추고 있고 비금속 개재물의 제어를 통해 높은 청정도를 지닌 강을 의미하며, 철강 제품의 품질은 2차 정련 공정에서 제어하는 것이 지배적이다. 2차 정련에서는 시간이 흐름에 따라 용강, 슬래그, 비금속 개재물, 내화물 및 합금원소 간의 복잡한 반응이 동시에 일어나기 때문에 공정에 대한 제어가 쉽지 않다. 따라서 이전 연구자들은 2차 정련의 공정 예측을 위해 Kinetic 기반의 시뮬레이션 모델을 발표하였고, 정밀한 공정 예측을 위해 현재까지 발표된 시뮬레이션 모델들의 검토 및 분석이 필요하다. 본 연구에서는 Coupled Reaction 모델 기반의 2차 정련 모델들을 분석 및 검토하였고, 시뮬레이션 결과를 검토하였다.

기계적합금법에 의한 $\textrm{TiB}_2$ 분말의 제조 및 Zr과 Ta이 합성에 미치는 영향 (Synthesis of $\textrm{TiB}_2$ Powder by Mechanical Alloying and the Effect of Zr and Ta Substitution for Ti)

  • 황연;강을손
    • 한국재료학회지
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    • 제9권8호
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    • pp.787-791
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    • 1999
  • 기계적합금법으로 Ti와 B의 혼합분말로부터 $TiB_2$분말을 제조하였고, Zr과 Ta의 Ti 치환 효과를 조사하였다. (Ti+B)의 혼합분말을 280시간 분쇄하여 $TiB_2$단일상을 얻었고 기계적합금화 도중 비정질상은 관찰되지 않았다. Ti의 일부를 원자반경이 Ti보다 큰 Zr으로 치환한 결과 기계적합금화에 걸리는 시간이 크게 감소한 반면에, 붕화물 생성열이 절대값이 $TiB_2$상보다 작은 Ta로 치환하면 280시간 분쇄하여도 단일상을 형성하지 못하였다.

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기계적합금화에 의한 Ti Silicide 화합물의 합성 (Synthesis of Titanium Silicides by Mechanical Alloying)

  • 변창섭;이상호;김동관;이진형
    • 한국분말재료학회지
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    • 제5권4호
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    • pp.250-257
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    • 1998
  • The synthesis of titanium silicides ($Ti_3Si$, $TiSi_2$, $Ti_5Si_4$, $Ti_5Si_3$ and TiSi) by mechanical alloying has been investigated. Rapid, self-propagating high-temperature synthesis (SHS) reactions were observed to produce the last three phases during room-temperature high-energy ball milling of elemental powders. Such reactions appeared to be ignited by mechanical impact in an intimate, fine powder mixture formed after a critical milling period. During the high-energy ball milling, the repeated impact at contact points leads to a local concentration of energy which may ignite a self-propagating reaction. From in-situ thermal analysis, each critical milling period for the formation of $Ti_5Si_4$, $Ti_5Si_3$ and TiSi was observed to be 22, 35.5 and 53.5 min, respectively. $Ti_3Si$ and $TiSi_2$, however, have not been produced even till the milling period of 360 min due to lack of the homogeneity of the powder mixtures. The formation of titanium silicides by mechanical alloying and the relevant reaction rates appeared to depend upon the critical milling period, the homogeneity of the powder mixtures, and the heat of formation of the products involved.

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