• 제목/요약/키워드: Sintering characteristics

검색결과 904건 처리시간 0.05초

상용 7xxx Series Al 합금계 혼합분말의 소결 특성 (A study on Sintering Characteristics of Commercial 7xxx Series Al Alloy Powders)

  • 공민석;배이태;민경호;;장시영;김영도
    • 한국분말재료학회지
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    • 제11권1호
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    • pp.69-73
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    • 2004
  • The sintering characteristics of commercial 7xxx series Al-Zn-Mg-Cu alloy have been investigated. Sintering system of this blended elemental powder has aspects of both transient and supersolidus liquid phase sintering. Transient liquids occur when the constitution point during sintering lies in a solid phase region but where the sintering temperature is greater than either the melting point of one of the constituent or a eutectic temperature. Supersolidus liquid phase sintering occurs when a preblended powder is heated to a temperature between the solidus and liquids. However, these reaction were restrained their inter diffusion due to the appearance of the oxide film. Thus, 7xxx series Al alloy is extremely sensitive to process variables, including particle size, holding time and sintering temperature. Therefore, above phenomenons were observed formation and behaviour of the liquid by using SEM and DSC.

Densification Kinetics of Steel Powders during Direct Laser Sintering

  • Simchi, Abdolreza;Petzoldt, Frank
    • 한국분말야금학회:학술대회논문집
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    • 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
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    • pp.250-251
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    • 2006
  • It is known that powder characteristics including particle size and distribution, particle shape, and chemical composition are important parameters which influence direct laser sintering of metal powders. In this paper, we introduce a first order kinetics model for densification of steel powders during laser sintering. A densification coefficient (K) is defined which express the potential of different powders to be laser-sintered to a high density dependent on their particle characteristics.

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소결층 내에서의 코크스와 무연탄의 연소 특성 비교 연구 (A Study on the Combustion Characteristics of Coke and Anthracite in an Iron Ore Sintering Bed)

  • 양원;양광혁;최상민;최응수;이덕원;김성만
    • 한국연소학회:학술대회논문집
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    • 한국연소학회 2004년도 제28회 KOSCO SYMPOSIUM 논문집
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    • pp.141-148
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    • 2004
  • Coal combustion in an iron ore sintering bed is a key parameter that determines quality of the sintered ores and productivity of the process. In this study, effects of the different types of coal coke and anthracite - on the combustion in the iron ore sintering bed are investigated by modeling and experiment. Fuel characteristics of coke and anthracite are observed through a few basic analysis and thermo-gravimetric analysis. It was found that coke has a higher reactivity than anthracite due to the difference of surface area and density. Those characteristics are reflected to the 1-D unsteady simulation of the iron ore sintering bed. Calculation results show that different reactivity of the fuel can affect the bed combustion, which implies the further investigation should be performed for obtaining optimal combustion conditions in the sintering bed.

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완전 소결에 의한 지르코니아 어뷰트먼트의 수축 등방성 평가 (Observation of the Shrinkage Characteristics of the Machined Zirconia Abutment by the full sintering process)

  • 이호철;박성준;김재덕
    • 한국생산제조학회지
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    • 제20권6호
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    • pp.729-734
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    • 2011
  • The full sintering process of zirconia has some extent of shrinkage and the custom abutment design should consider the pre-compensation volume of the shape. In this paper, we concentrated to reveal the asymmetric sintering characteristics. The circular profile of all six samples were measured using the three dimensional coordinate machine. After the full sintering process, the profiles were measured again. The roundness were compared to those of the original shapes and the percent of shrinkage were calculated. On the other hand, surface roughness was also investigated after the full sintering process. The final average surface roughness was improved by the sintering of the machined zirconia surface.

$TiO_2$ 소성 조건 변화에 따른 염료감응형 태양전지의 특성 연구 (Characteristics of dye-sensitized solar cell on different $TiO_2$ sintering conditions)

  • 손민규;서현웅;이경준;홍지태;김정훈;김희제
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 2008년도 제39회 하계학술대회
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    • pp.1256-1257
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    • 2008
  • Dye-Sensitized Solar Cell(DSSC) is a new type of solar cell by using photocatalytic properties of $TiO_2$. The size and shape of $TiO_2$ particle are two of important parameters that are related to the characteristics of DSSC. And these can be changed by controlling $TiO_2$ sintering conditions especially temperature. The particles of $TiO_2$ are classified anatase and rutile. Anatase particles are created at low sintering temperature and rutile particles are created at high sintering temperature. Anatase particles have advantages such as increased surfaces that cause more attached dye molecules, and fast electron transportation. And rutile particles have advatages such as more efficient light scattering. Therefore, we studied characteristics of DSSC in this paper as $TiO_2$ sintering temperature is varied. As a result, we found that characteristics of DSSC are very good in the case that anatase and rutile particles are together and this sintering temperature is 450$^{\circ}C$.

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ZPCCY계 바리스터의 써지 스트레스 특성에 소결시간의 영향 (Effect of Sintering Time on Surge Stress Characteristics of ZPCCY-Based Varistors)

  • 박종아;김명준;유대훈;남춘우
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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    • pp.408-411
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    • 2004
  • The electrical stability against surge stress of ZPCCY-based varistors were investigated at different sintering times. Sintering time decreased the varistor voltage and nonlinear exponent from 279.6 to 179.1 and from 52.5 to 24.9, respectively. On the contrary, the leakage current and dielectric dissipation factor increased from 1.2 to 9.8 ${\mu}A$ and from 0.0461 to 0.0651 with increase of sintering time. For all varistors, the variation rates of V-I characteristic parameters against surge stress were affected in order of varistor voltage$\rightarrow$nonlnear exponent$\rightarrow$leakage current. On the whole, the electrical stability against surge stress increased with increasing sintering time. Conclusively, it is assumed that the varistor sintered for 2 h exhibited comparatively good characteristics, in view of overall characteristics.

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소결층 내에서의 코크스와 무연탄의 연소 특성 비교 연구 (A Study on the Combustion Characteristics of Coke and Anthracite in an Iron Ore Sintering Bed)

  • 양원;양광혁;최응수;이덕원;김성만;최상민
    • 한국연소학회지
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    • 제9권2호
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    • pp.30-37
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    • 2004
  • Coal combustion in an iron ore sintering bed is a key parameter that determines quality of the sintered ores and productivity of the process. In this study, effects of the different types of coal - coke and anthracite - on the combustion in the iron ore sintering bed are investigated by modeling and experiment. Fuel characteristics of coke and anthracite are observed through a set of basic analysis and thermo-gravimetric analysis. Coke has a higher reactivity than anthracite due to the difference of surface area and density, and these characteristics are reflected in the 1-D unsteady simulation of the iron ore sintering bed. Calculation results show that different reactivity of the fuel can affect the bed combustion.

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ZnO-Bi2O3계 세라믹스의 미세구조 및 전기적 특성 (Microstructure and Electrical Characteristics of ZnO-Bi2O3 Ceramics)

  • 이승주;한상목
    • 한국세라믹학회지
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    • 제25권6호
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    • pp.645-654
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    • 1988
  • The microstructure and electrical characteristics of ZnO-Bi2O3 ceramics containing 5mol% Bi2O3 have been studied in relation to sintering temperature and mode. The distribution and thickness of Bi2O3 intergranular layer was varied with sintering temperature and mode. Intergranular layer was more homogeneous with increasing sintering temperature, when sintering by direct heating and rapid cooling mode showed the best distribution of intergranular layer. These microstructural changes affected electrical characteristics directly, at 140$0^{\circ}C$ and C mode obtained high value of electrical resistivity and nonlinear exponent. Varistor voltage decreased with increasing sintering temperature, increased with decreasing holding time at high temperature. Barrier voltage obtained by calculation was about 1.5V.

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Electrical Properties and Dielectric Characteristics CCT-doped Zn/Pr-based Varistors with Sintering Temperature

  • Nahm, Choon-Woo
    • Transactions on Electrical and Electronic Materials
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    • 제10권3호
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    • pp.80-84
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    • 2009
  • The microstructure, voltage-current, capacitance-voltage, and dielectric characteristics of CCT doped Zn/Pr-based varistors were investigated at different sintering temperatures. As the sintering temperature increased, the average grain size increased from 4.3 to 5.1 ${\mu}m$ and the sintered density was saturated at 5.81 g $cm^{-3}$. As the sintering temperature increased, the breakdown field decreased from 7,532 to 5,882 V $cm^{-1}$ and the nonlinear coefficient decreased from 46 to 34. As the sintering temperature increased, the donor density, density of interface states, and barrier height decreased in the range of (9.06-7.24)${\times}10^{17}\;cm^{-3}$, (3.05-2.56)${\times}10^{12}\;cm^{-2}$, and 1.1-0.95 eV, respectively. The dielectric constant exhibited relatively low value in the range of 529.1-610.3, whereas the $tan{\delta}$ exhibited a high value in the range of 0.0910-0.1053.

소결치차의 피로강도에 관한 연구 (A Study on the Bending Fatigue Strength of Sintering Spur Gear)

  • 류성기;김경모
    • 한국안전학회지
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    • 제9권3호
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    • pp.28-33
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    • 1994
  • It is very important to have exact informations on the properties and characteristics of the sintering material as a new material of machine elements. To study the sintering spur gear and the sintering specimen to be consisted of Fe-Cu-C, the constant stress amplitude fatigue test is performed by using an electrohydrolic survo-controlled pulsating tester. Consequently, the S-N curves are obtained and the fatigue strength is compared with flaw depth. Accordingly, this study presents the fatigue strength of sintering spur gears, the critical notch depth of sintering materials and the effects of flaw depth on the bending fatigue strength.

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