• 제목/요약/키워드: gravity casting

검색결과 78건 처리시간 0.027초

Al-Si/$SiC_p$ 복합재료에서 SiC의 편석에 미치는 응고 조건의 영향 (Influence of Solidification Condition on the Segregation of SiC Particles in the Al-Si/$SiC_p$ Composites)

  • 김종찬;권혁무
    • 한국주조공학회지
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    • 제17권2호
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    • pp.180-187
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    • 1997
  • The influence of solidification condition on the segregation of SiC particles in the $Al-xSi/6wt%SiC_p$(x: 6, 10, 14, 18${\cdot}$wt%) composites was investigated in the study. The results are as follows: 1) During the counter-gravity unidirectional solidification of $Al-Si/SiC_p$ composites melt, most of the SiC particles are pushed to the top of the casting. 2) The SiC particles pushing in the $Al-Si/SiC_p$ composite melts are not observed, when the interface velocity of melts increases more than 1.41 ${\mu}m/sec$. 3) The SiC particles are entrapped in the interdendrite regions, when the sizes of SiC particles in the $Al-Si/SiC_p$ composites are large than ${\varphi}22{\mu}m$.

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래들에 의한 재해발생 실태와 예방대책 (The Status of Accident and Prevention Measures for Ladles)

  • 최승주;신운철
    • 대한안전경영과학회지
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    • 제16권3호
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    • pp.201-207
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    • 2014
  • This study is aimed to improve safety of ladle in the metal products manufacturing industry. Burns may occur from spills, spatters or eruptions of hot metal from ladles during pouring or transporting. According to the statistics of occupational accidents about the ladle, many victims were exposed to or contacted with extreme temperatures. The many fatal injuries occurred as a result of unexpected discharging of molten metal due to tipping over ladles. To prevent ladles from turning over, the trunnion axis shall be located below the center of gravity of the ladle at all operating condition. For this purpose, the equation is proposed to calculate the minimum location of a trunnion axis for definite static stability when tilting.

기계적 밀링 공정을 이용한 준결정 강화 알루미늄 복합재료의 제조 (Fabrication of Quasi-crystal Strengthened Aluminum Composites by Mechanical Milling Process)

  • 장우길;신광선
    • 한국분말재료학회지
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    • 제12권3호
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    • pp.208-213
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    • 2005
  • Aluminum matrix composites strengthened by the quasi-crystalline (QC) phase were developed in the present study. The icosahedral $Al_{65}Cu_{20}Fe_{15}$ phase was produced by gravity casting and subsequent heat treatment. The mechanical milling process was utilized in order to produce the Al/QC composite powders. The microstructures of the composite powders were examined by optical microscopy (OM) and scanning electron microscopy (SEM). The composite powders were subsequently canned, degassed and extruded in order to produce the bulk composite extrusions with various volume fractions of QC. The microstructure and mechanical properties of the extrusions were examined by OM, SEM, Vickers hardness tests and compression tests. It was found that the microstructures of the Al/QC composites were uniform and the mechanical properties could be significantly improved by the addition of the QC phase.

Sc 첨가에 따른 Al-6Si-2Cu 합금의 미세조직 개량화 (Effect of Sc Addition on the Microstructure Modification of Al-6Si-2Cu Alloy)

  • 안성빈;김정석
    • 열처리공학회지
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    • 제35권3호
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    • pp.150-158
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    • 2022
  • The effects of scandium addition on the Al-6Si-2Cu Alloy were investigated. The Al-6Si-2Cu-Sc alloy was prepared by gravity die casting process. In this study, scandium was added at 0.2 wt%, 0.4 wt%, 0.8 wt%, and 1.0 wt%. The microstructure of Al-6Si-2Cu-Sc alloy was investigated using Optical Microscope, Field Emission Scanning Electron Microscope, Electron Back Scatter Diffraction, and Transmission Electron microscope. The microstructure of Al-6Si-2Cu alloy with scandium added changed from dendrite structure to equiaxed crystal structure in specimens of 0.4 wt% Sc or more, and coarse needle-shape eutectic Si and β-Al5FeSi phases were segmented and refined. The nanosized Al3Sc intermetallic compound was observed to be uniformly distributed in the modified Al matrix.

Mg-Zn-Cu 합금의 Zn, Cu 첨가량에 따른 전기전도도 특성 (Electrical Conductivity by Addition of Zn and Cu on Mg-Zn-Cu Alloys)

  • 예대희;김현식;강민철;김정대;정해용
    • 한국주조공학회지
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    • 제34권3호
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    • pp.100-106
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    • 2014
  • In recent years, Mg and its alloys have attracted a great deal of attention due to their low density, relatively excellent castability, and straightforward recyclability. Mg alloys have been widely applied to various industrial fields, and are representatively used in automotive and electronic parts. According to previous researches, the electrical conductivity of Mg alloys greatly decreases with increasing Al content. However, with the addition of Zn and/or Cu, the electrical conductivity of Mg alloys is maintained or slightly increased, and improved mechanical properties are obtained as well. On this basis, Mg-Zn-Cu alloys have been investigated in the present study with a focus on the effect of adding Zn and Cu on the electrical conductivity. The Zn and Cu contents ranged from 4 to 6wt.% and 0 to 1.5wt.%, respectively. Ternary Mg-Zn-Cu alloys have been prepared by gravity casting in a steel mold. In the as-casting condition, the electrical conductivity of Mg-Zn-Cu alloys showed a linear increasing trend with decreasing Zn and increasing Cu contents. Furthermore, impact values of Zn = -1.5 and Cu = 2.5 were determined for these alloys by electrical conductivity tests.

Hyper Duplex STS 중 Ce 첨가 시 비금속개재물 생성거동 (The Formation Behavior of Non-metallic Inclusion in the Ce-added Hyper Duplex STS)

  • 홍성훈;장필용;박영민;변선민;김광태;유병돈
    • 소성∙가공
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    • 제19권5호
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    • pp.311-319
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    • 2010
  • Rare earth metal Ce has a relatively low melting point and high specific gravity. Because of its significantly high affinity to oxygen, nitrogen and sulfur, it is highly usable as a steel refining agent. However, because Ce compound has relatively high specific gravity, it is difficult to be separated from molten steel through floatation, and it degrades the purity of molten steel, or may clog the nozzle in continuous casting. Such problem may be solved by using an appropriate deoxidation agent together with Ce and settling molten steel sufficiently after refining. Thus a fundamental study in the formation behavior of non-metallic inclusion in Ce added Hyper Duplex STS melts was investigated. The addition amount of Ce, melt temperature were considered as experimental variables. A main non-metallic inclusion in mother alloy is 51(wt%MnO) - 27.6(wt%SiO$_2$)- 10.9(wt%$Cr_2O_3$). Non-metallic inclusion was dramatically decreased and the particle size was fined as the amount of Ce increased. Moreover (%MnO) and (%SiO$_2$) of non-metallic inclusion were decreased. But (%$Al_2O_3$)were relatively increased. The number of non-metallic inclusion were decreased and the large particle size were increased by increasing the temperature of molten steel.

저회의 계면 화학적 특성 규명 (Characterization of interfacial chemistry on the coal bottom ash)

  • 이기강
    • 한국결정성장학회지
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    • 제21권2호
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    • pp.92-97
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    • 2011
  • 화력발전소에서 발생하는 석탄회의 일종인 저회는 현재 적절한 재활용 방법이 연구 되지 않아 대부분 매립에 의존하고 있는 실정이다. 본 연구에서는 비가소성 분체인 저회의 재활용율을 높이며, 저회를 점토 대체 원료로 재활용하기 위하여 저회와 점토의 계면화학적 성질을 조절하여 Bottom-ash(B/A)-Hard Clay(H/C) 소지의 물성변화를 관찰하였다. H/C 100 %, H/C60 % + B/A40 %에 대하여 각 조성별 pH에 따른 침강높이를 관찰한 결과 점토와 저회는 계면 화학적 성질이 비슷하여 혼합하여 슬립제조 시 hetero-polar 응집현상이 없었다. 또한 각 조성별 점도가 조절된 Slip을 주입 성형하여 $1100{\sim}1250^{\circ}C$에서 $50^{\circ}C$ 간격으로 소결하여 각 시편에 대한 비중, 흡수율을 측정하고 미세구조를 관찰하였다. 그 결과 분산된 점토와 저회 슬립은 Bingham 가소성 거동을 보이므로 주입성형 및 가소성형이 가능하며, 분산된 점토와 저회 슬립으로부터제조된 소결체는 $1250^{\circ}C$에서 KSL 4201과 KSL 1001의 규격을 만족할 뿐 아니라 특히 비중이 약 15 % 이상 경량이므로 도자기나 위생도기 등의 소지로 응용 가능성이 있다고 사료된다.

자동차 경량소재 AlSiCu 합금의 기계적 특성을 개선하기 위한 최적의 이중 열처리공정 (Optimal Double Heat Treatment Process to Improve the Mechanical Properties of Lightweight AlSiCu Alloy)

  • 박상규;김정석
    • 한국기계가공학회지
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    • 제17권3호
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    • pp.102-108
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    • 2018
  • The objective of this study is to develop the mechanical properties of an AlSiCu aluminum alloy using the two-step solution heat treatment. The microstructure of the gravity casting specimen represents a typical dendrite structure with a secondary dendrite arm spacing (SDAS) of 40 um. In addition to the Al matrix, a large amount of coarsen eutectic Si phase, $Al_2Cu$ intermetallic phase, and Fe-rich phases is generated. The eutectic Si phases are fragmented and globularized with the solution heat treatment. The $Al_2Cu$ intermetallic phase is also resolutionized into the Al matrix. The $2^{nd}$ solution temperature at $525^{\circ}C$ may be an optimal condition to enhance the mechanical properties of the AlSiCu aluminum alloy.

소실모형주조용 조형장치의 진동특성 평가 (Vibration Characteristics of Compaction Table for Expendable Pattern Casting Process through Changing Vibration Modes)

  • 이강래;최경환;조규섭;이경환;김명호;임경화;김기영
    • 한국주조공학회지
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    • 제24권5호
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    • pp.273-280
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    • 2004
  • Vibrational motions of the compaction table were investigated to select the optimal operation conditions of sand filling and compaction for the EPC process. Their modes were measured at the nine points of the table with changing the relative rotation angles between the two eccentric mass vibrators which were attached parallel beneath the table. Well-defined vibration modes were measured at the center of the table but those of left and right sides of the table were distorted regardless of rotational angle differences. The distortion of vibration modes at both sides of the table were caused by the moment generated by offset positions of two eccentric masses. It was found that the uniform vibration modes would be gathered by controlling the relative distances between the rotating axis and the center of gravity in the compaction system at the various conditions of vibration modes and rotational angle differences.

Zn 첨가량에 따른 Al-Si-Mg-Cu계 합금의 미세조직 및 기계적 특성변화 (Effect of Zn additions on the Mechanical Properties of High Strength Al-Si-Mg-Cu alloys)

  • 황수빈;김병주;정성수;김동규;이영철
    • 한국주조공학회지
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    • 제39권3호
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    • pp.33-43
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    • 2019
  • In this study, the effects of Zn additions on the mechanical properties of Al-Si-Mg-Cu alloys were investigated by increasing the amount of Zn up to 8wt.%. As the Zn content was increased up to 6 wt.%, the yield strength and elongation changed linearly without any significant changes in the size and shape of the main reinforcement phase. However, it was confirmed by SEM observation that the Mg-Zn phase formed between the reinforcement phases when the amount of Zn added exceeded 7wt.%. A Mg-Zn intermetallic compound formed between the $Mg_2Si$ phase, becoming a crack initiation point under stress. Thus, the formation of the Mg-Zn phase may cause a sharp decrease in the elongation when Zn at levels exceeding 7 wt.%. It was also found that the matrix became more brittle with increasing the Zn content. From these results, it can be concluded that the formation of the Mg-Zn intermetallic compound and the brittle characteristics of the matrix are the main causes of the remarkable changes in the mechanical properties of this alloy system