• 제목/요약/키워드: Alloying reaction

검색결과 109건 처리시간 0.024초

PbTe 열전재료의 기계적 합금화 거동 (Mechanical alloying behavior of PbTe thermoelectric materials)

  • 오태성;최재식;현도빈
    • 한국재료학회지
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    • 제5권2호
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    • pp.223-231
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    • 1995
  • 열전발전용 재료인 PbTe의 밀링 시간, 볼과 분말의 무게비에 따른 기계적 합금화 거동을 연구하였다. Pb와 Te 분말을 볼과 분말의 무게비 2 : 1에서 2분간 기계적 합금화 함으로써 PbTe 금속간 화합물의 형성이 완료되었다. 밀링 공정중 vial 표면 온도의 in situ 측정에서 기계적 합금화에 의한 PbTe 금속간 화합물의 형성이 분말 계면에서의 확산 공정보다는 합금화 반응이 자발적으로 전파하는 자전 반응에 의하여 이루어지는 것을 알 수 있었다. 기계적 합금화로 제조한 PbTe 합금분말의 격자상수는 0.6462nm로 용해 및 분쇄법으로 제조한 PbTe 분말에서 보고된 값인 0.6459nm와 잘 일치하였으며, 밀링 시간의 증가 및 볼과 분말의 무게비의 변화에 의하여 변하지않았다.

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Effects of Sulfuric Acid Concentration and Alloying Elements on the Corrosion Resistance of Cu-bearing low Alloy Steels

  • Kim, Ki Tae;Kim, Young Sik
    • Corrosion Science and Technology
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    • 제17권4호
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    • pp.154-165
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    • 2018
  • During the process of sulfur dioxide removal, flue gas desulfurization equipment provides a serious internal corrosion environment in creating sulfuric acid dew point corrosion. Therefore, the utilities must use the excellent corrosion resistance of steel desulfurization facilities in the atmosphere. Until now, the trend in developing anti-sulfuric acid steels was essentially the addition of Cu, in order to improve the corrosion resistance. The experimental alloy used in this study is Fe-0.03C-1.0Mn-0.3Si-0.15Ni-0.31Cu alloys to which Ru, Zn and Ta were added. In order to investigate the effect of $H_2SO_4$ concentration and the alloying elements, chemical and electrochemical corrosion tests were performed. In a low concentration of $H_2SO_4$ solution, the major factor affecting the corrosion rate of low alloy steels was the exchange current density for $H^+/H_2$ reaction, while in a high concentration of $H_2SO_4$ solution, the major factors were the thin and dense passive film and resulting passivation behavior. The alloying elements reducing the exchange current density in low concentration of $H_2SO_4$, and the alloying elements decreasing the passive current density in high concentration of $H_2SO_4$, together play an important role in determining the corrosion rate of Cu-bearing low alloy steels in a wide range of $H_2SO_4$ solution.

CO2 레이저에 의한 Ti-6Al-4V 합금(合金)의 TiN 표면합금화(表面合金化) (TiN Surface-Alloying of Ti-6Al-4V Alloy by CO2 Laser)

  • 박상덕;이오연;송기흥
    • 열처리공학회지
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    • 제8권1호
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    • pp.32-43
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    • 1995
  • Ti-6Al-4V alloy are widely used in chemical and aircraft industries for their good corrosion resistance and high strength to weight ratio. Surface alloying of Ti alloy by $CO_2$ laser is able to produce few hundred micrometers thick TiN surface-alloyed layer with high hardness on the substrate very simplely by injecting reaction gas($N_2$) into a laser-generated melt pool and adjust the hardness to the specific requirements of the individual application by changing of laser processing parameters. This research has been investigated the effect of such parameters on TiN surface-alloying of Ti-6Al-4V alloy by $CO_2$ laser. The maximum hardness of TiN surface-alloyed zone waw obtained by injecting 100% $N_2$ gas and it was decreased as the amount of $N_2$ gas in Ar and $N_2$ gas mixture was decreased. As scanning speed was increased, the hardness and depth of TiN surface-alloyed zone was decreased at constant laser power. The surface hardness after double scanning laser treatment is higher than that of single scanning. At constant laser power, the surface roughness is increased after the surface alloying if laser scanning speed is decreased.

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직류전원부하에 의한 지르코니아와 금속의 접합 (A Study on the Metal to Zirconia Joining by Applying Direct Current)

  • 김성진;김문협;박성범;권원일
    • 한국전기화학회:학술대회논문집
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    • 한국전기화학회 2005년도 수소연료전지공동심포지움 2005논문집
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    • pp.383-390
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    • 2005
  • Effect of applying a DC voltage on the interfacial reaction at the metal to zirconia interface was investigated utilizing an oxygen ionic conductivity of partially stabilized zirconia. The joining of copper rod and zirconia tube was carried out in Ar gas atmosphere at $1000^{\circ}C$. There are two type of the joining. The one is the reaction bond consisting of copper and zirconia was dominated by surface reaction with a undetectable very thin layer. It was found that copper elements were diffused to zirconia side, but that Zr ions were not diffused to copper side. These results mean application of a DC voltage to migrate oxygen to the copper-zirconia interface can oxidize metal at the copper-zirconia interface and the bonding reaction between zirconia and copper oxide may occur. The other is the reaction bonding was dominated by interdiffusion with a very thick interface layer. This result mean application of a DC voltage can reduce zirconia at the interface. The bonding reaction is to be an alloying between Zr and Cu.

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합금화 용융아연 도금강판의 합금화 거동에 미치는 실리콘의 영향 (Effect of silicon on alloying behavior of hot-dip galvannealed steel sheets)

  • 이호종;김종상
    • 한국표면공학회지
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    • 제32권2호
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    • pp.134-143
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    • 1999
  • The effects of silicon on galvannealing behavior of interstitial-free (IF) steels were studied. The growth rate of the Fe-Zn alloy layer was retarded as silicon in the steel added. Titanium in steel strongly favors Fe-Zn reaction, in particular outburst structures, whereas silicon inhibit them. Cross-sectional and planar views of galvannealed coatings were investigated to characterize alloy phase development. A possible mechanism to explain the retardation effect of silicon is discussed in terms of concentration on surface and inhibition layer.

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기계적 합금화에 의한 (V, Fe)-N계 비정질 합금의 제조 및 구조변화 (Mechanical alloying effect and structural observation of (V, Fe)-N amorphous alloy powders)

  • 이충효;전성용;김지순
    • 한국결정성장학회지
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    • 제14권4호
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    • pp.129-134
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    • 2004
  • 본 연구에서는 기계적 합금화(MA)에 의한 고상-기상반응에 있어서 질소원자가 V-Fe계 합금의 비정질화에 미치는 영향을 조사하였다. 유성형 볼밀을 사용하여 $V_{70}Fe_{30}$혼합분말을 질소가스 분위기 중 MA 처리하였다. 그 결과 160시간 MA 처리에 의하여 비정질상이 생성됨을 알 수 있었다. 160시간 동안 MA 처리한 ($V_{70}Fe$_{30}$)_{0.89}N_{0.11}$ 분말시료의 열분석 결과 약 $600^{\circ}C$에 비정질상의 결정화에 의한 발열 peak가 관찰되었다. 또한 bcc 결정에서 비정질상으로의 구조변화 과정을 X선 및 중성자 회절법을 통하여 조사하였으며, 특히 중성자회절에서는 V원자의 중성자에 대한 간섭성 핵산란진폭이 매우 작은 특징을 이용하였다. 그 결과, 이 합금계에서의 비정질화는 모든 결정구조에서 전형적으로 존재하는 8면체 unit가 우선적으로 붕괴되어 4면체 unit로 변환되어 가는 과정임을 알 수 있었다. 또한 중성자 회절에 의한 구조해석 결과 질소원자는 V원자로 이루어진 다면체의 중심에 위치하고 있음을 알 수 있었다.

기계적 합금화법으로 제조된 $Mg_2Ni$-5mass% Nb 복합재료의 수소화 특성평가 (Hydrogenation Properties of $Mg_2Ni$-5mass% Nb Composites by Mechanical Alloying)

  • 석송;연규붕;김경일;유성웅;조경원;김기배;홍태환
    • 한국수소및신에너지학회논문집
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    • 제17권4호
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    • pp.389-394
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    • 2006
  • Mg and Mg-based alloys are promising hydrogen storage alloys for renewable clean energy applications. It is a lightweight and low cost material with high hydrogen storage capacity. However, commercial applications of the Mg hydride are currently hindered by its high absorption/desorption temperature, and very slow reaction kinetics. In this work, we aim to study the absorption properties of the $Mg_2Ni$-5mass% Nb composite prepared by mechanical alloying under hydrogen. The absorption capacity of the sample is found to be about 3.0 wt.% at T=573 K and P=1.0 MPa. The absorption characteristics observed have been compared with those of the prepared $Mg_2Ni$.

MA법에 의한 V-Co계 비정질합금의 제조 및 구조분석 (Fabrication and structural observation of amorphous V-Co alloy by mechanical alloying)

  • 이충효
    • 한국결정성장학회지
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    • 제22권1호
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    • pp.51-56
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    • 2012
  • 본 연구에서는 출발원료로 ${\sigma}$-VCo 금속간화합물과 $V_{50}Co_{50}$ 혼합분말을 각각 사용하여 기계적 합금화에 따른 비정질화 가능성을 조사하였다. X선 회절에 의해 얻어진 전구조인자 S(Q) 및 동경분포함수 RDF(r)의 결과로부터 볼밀링이 진행됨에 따라 비정질상의 구조적 특징이 분명히 관찰되었다. 120시간 MA 처리에 의하여 두 경우 모두에서 비정질상이 생성됨을 알 수 있었다. 60시간 동안 MA 처리한 $V_{50}Co_{50}$ 분말시료의 열분석 에서는 약 $600^{\circ}C$에 비정질상의 결정화에 의한 발열 peak가 관찰되었다. X선 회절법에 의해 얻어진 전구조인자 및 동경분포함수의 분석으로부터 MA 시간에 따라 출발 결정상은 비정질상의 특징적인 원자구조로 서서히 변화함을 알 수 있었다.

수소 가압형 기계적 합금화법에 의한 $MgH_x-V_2O_5$ 복합재료의 수소와 특성 (Hydrogenation Properties of $MgH_x-V_2O_5$ Composites by Hydrogen Induced Mechanical Alloying)

  • 정미원;박지희;조경원;김경일;최재하;김상헌;홍태환
    • 한국수소및신에너지학회논문집
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    • 제21권1호
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    • pp.58-63
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    • 2010
  • Mg and Ma-based alloys are promising hydrogen storage materials for renewable clean energy applications. It has high hydrogen storage capacity (7.6wt.%), lightweight and low economical materials. However, commercial applications of the Mg hydride are currently hindered by its high operating temperature, and very slow reaction kinetics. In this work, we are aimed at studying the hydrogenation properties of the $MgH_x-V_2O_5$ composite prepared by hydrogen induced mechanical alloying. The absorption capacity of the sample is found to be about 4.7wt.% at 623K under 3 MPa $H_2$ pressure. The absorption characteristics observed have been compared with prepared $MgH_x$.

기계적 합금화법으로 제조된 $MgH_x-Fe_2O_3$ 복합재료의 수소화 특성 평가 (The Evaluation of Hydrogenation Properties on $MgH_x-Fe_2O_3$ Composite by Mechanical Alloying)

  • 석송;조경원;홍태환
    • 한국수소및신에너지학회논문집
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    • 제18권1호
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    • pp.26-31
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    • 2007
  • Hydrogen has a high potential to be a renewable substitute for fossil fuels, because of its high gravimetric energy density and environment friendliness. In particular, Magnesium have attracted much interest since their hydrogen capacity exceeds that of known metal hydrides. One of the approaches to improve the kinetic is addition of metal oxide. In this paper, the effect of $Fe_2O_3$ concentration on the kinetics of Mg hydrogen absorption reaction was investigated. $MgH_x-Fe_2O_3$ composites have been synthesized by hydrogen induced mechanical alloying. The powder synthesized was characterized by XRD, SEM and simultaneous TG, DSC analysis. The hydrogenation behaviors were evaluated by using a sievert's type automatic PCT apparatus. Absorption and desorption kinetics of Mg catalyzed with 5,10 mass% $Fe_2O_3$ are determined at 423, 473, 523, 573, 623K.