• 제목/요약/키워드: High pure aluminum powder

검색결과 17건 처리시간 0.026초

분말시스압연법에 의해 제조된 알루미늄 분말성형체의 조직 및 기계적 성질 (Microstructure and Mechanical Property of Aluminum Powder Compact by Powder-in Sheath Rolling Method)

  • 이성희
    • 한국분말재료학회지
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    • 제9권3호
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    • pp.153-160
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    • 2002
  • A nitrogen gas atomized aluminum powder was consolidated by powder-in sheath rolling method. A pure aluminum tube with outer diameter of 12 mm and wall thickness of 1mm was used as a sheath. The aluminum tube filled with the aluminum powder, first, was cold-rolled to the thickness of 6mm for performing, and then consolidated by the cold rolling and/or subsequent hot rolling at 360, 460 and $560^{\circ}C$. The aluminum powder compact fabricated by the sheath rolling showed high relative density more than 0.96 at any rolling conditions. The 0.2% proof stress increased with increasing hot rolling reduction and hot rolling temperature. Tensile strength was hardly affected by change in the hot rolling reduction, whereas it decreased with increasing hot rolling temperature. The powder compact showed the large elongation when cold rolling or hot rolling reduction was large. It was found that the sheath rolling was an effective method for consolidation of aluminum powder.

자전 고온 합성법에 의한 질화 알루미늄 휘스커의 제조 (Fabrication of AlN Whiskes by Self-propagating High-temperature Synthesis)

  • 이경재;장영섭;김석윤;김용석
    • 한국세라믹학회지
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    • 제32권8호
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    • pp.931-937
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    • 1995
  • AlN powder and whiskers were synthesized by direct nitridation of aluminum powder in pure nitrogen atmosphere. The nitridation reaction of aluminum powder was initiated by heating the sample to the ignition temperature and the reaction was finished in less than 3 minutes. AlN whisker-shaped morphology was observed predominantly when the sample was heated above 90$0^{\circ}C$.

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분말시스압연법에 의한 CNT 강화 Al기 복합재료의 제조 및 평가 (Fabrication and Evaluation of Carbon Nanotube Reinforced Al Matrix Composite by a Powder-in-sheath Rolling Method)

  • 이성희;홍동민
    • 한국분말재료학회지
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    • 제21권1호
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    • pp.50-54
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    • 2014
  • A powder-in-sheath rolling method was applied to a fabrication of a carbon nano tube (CNT) reinforced aluminum composite. A STS304 tube with an outer diameter of 34 mm and a wall thickness of 2 mm was used as a sheath material. A mixture of pure aluminum powders and CNTs with the volume contents of 1, 3, 5 vol was filled in the tube by tap filling and then processed to 73.5% height reduction by a rolling mill. The relative density of the CNT/Al composite fabricated by the powder-in-sheath rolling decreased slightly with increasing of CNTs content, but exhibited high value more than 98. The grain size of the aluminum matrix was largely decreased with addition of CNTs; it decreased from $24{\mu}m$ to $0.9{\mu}m$ by the addition of only 1 volCNT. The average hardness of the composites increased by approximately 3 times with the addition of CNTs, comparing to that of unreinforced pure aluminum. It is concluded that the powder-in-sheath rolling method is an effective process for fabrication of CNT reinforced Al matrix composites.

Cold Compaction Behavior of Nano and Micro Aluminum Powder under High Pressure

  • Kim, Dasom;Park, Kwangjae;Kim, Kyungju;Cho, Seungchan;Hirayama, Yusuke;Takagi, Kenta;Kwon, Hansang
    • Composites Research
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    • 제32권3호
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    • pp.141-147
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    • 2019
  • In this study, micro-sized and nano-sized pure aluminum (Al) powders were compressed by unidirectional pressure at room temperature. Although neither type of Al bulk was heated, they had a high relative density and improved mechanical properties. The microstructural analysis showed a difference in the process of densification according to particle size, and the mechanical properties were measured by the Vickers hardness test and the nano indentation test. The Vickers hardness of micro Al and nano Al fabricated in this study was five to eight times that of ordinary Al. The grain refinement effect was considered to be one of the strengthening factors, and the Hall-Petch equation was introduced to analyze the improved hardness caused by grain size reduction. In addition, the effect of particle size and dispersion of aluminum oxide in the bulk were additionally considered. Based on these results, the present study facilitates the examination of the effect of particle size on the mechanical properties of compacted bulk fabricated by the powder metallurgy method and suggests the possible way to improve the mechanical properties of nano-crystalline powders.

구리튜브를 피복재로 이용한 분말시스압연법에 의해 제조된 CNT/Al 복합재료의 미세조직 및 기계적 특성 (Microstructure and Mechanical Properties of CNT/Al Composite Fabricated by a Powder-in-Sheath Rolling Method utilizing Copper Tube as a Sheath)

  • 이성희
    • 한국분말재료학회지
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    • 제21권5호
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    • pp.343-348
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    • 2014
  • A powder-in-sheath rolling (PSR) process utilizing a copper alloy tube was applied to a fabrication of a multi-walled carbon nanotube (CNT) reinforced aluminum matrix composite. A copper tube with an outer diameter of 30 mm and a wall thickness of 2 mm was used as a sheath material. A mixture of pure aluminum powders and CNTs with the volume contents of 1, 3, 5 vol% was filled in the tube by tap filling and then processed to 93.3% height reduction by a rolling mill. The relative density of the CNT/Al composite fabricated by the PSR decreased slightly with increasing of CNTs content, but showed high value more than 98%. The average hardness of the 5%CNT/Al composite increased more than 3 times, compared to that of unreinforced pure Al powder compaction. The hardness of the CNT/Al composites was some higher than that of the composites fabricated by PSR using SUS304 tube. Therefore, it is concluded that the type of tube affects largely on the mechanical properties of the CNT/Al composites in the PSR process.

다공성 소결 순 Al에서 인장연성 변화에 관한 연구 (A Study on the Variation of Tensile Ductility in Porous Sintered Pure Aluminum)

  • 정재영
    • 소성∙가공
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    • 제27권2호
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    • pp.93-99
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    • 2018
  • An analytical solution for the tensile ductility in porous ductile materials was derived based on an Irwin's approach of the elastic-plastic deformation in fracture mechanics. This was in good agreement with the experimental results of a tensile ductility in a sintered pure Al, and could solve the discrepancies in the Brown and Embury, or the McClintock models. This model was also offered as an advanced analytical solution considering the effect of stress triaxiality of pore tip in addition to pore interactions, material properties of matrix, and local deformation effect around pore. The evaluation of an analytical solution in the sintered pure Al powder compacts showed that the tensile ductility depends not only on the volume fraction of pores, but also on the pore size and on the mechanical properties of the matrix. The tensile ductility of the sintered pure Al compacts decreased rapidly with the increasing of a pore volume fraction, despite of the excellent tensile ductility of the matrix. This significant decrease in the tensile ductility was mainly attributed to the low yield strength of the matrix and small pore size. Particularly, the effects of the large radius and high volume fraction of the pore on the tensile ductility in Al-Form, were thus reasonably predicted by this analytical equation.

플라즈마 용사에 의해 제조한 $Al-SiC_{p}$ 복합재료 코팅층의 고온마찰특성 (High Temperature Friction Characteristic of $Al-SiC_{p}$ Composite Coating Prepared by Plasma Thermal Spray)

  • 민준원;유승을;서동수
    • Tribology and Lubricants
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    • 제19권5호
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    • pp.274-279
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    • 2003
  • $Al-SiC_{p}$ composite layer was prepared by plasma thermal spray on aluminum substrate. The homogeneously dispersed composite powder for thermal spray was fabricated by mechanical alloying with ball mill. The friction tests of the composite layers and commercial aluminum alloys for comparison were performed in the temperature range of 20∼$260^{\circ}C$ with the interval of $40^{\circ}C$ with steel counter-face. Friction coefficient was recorded during test sequence, and the microstructure of surface and debris was investigated by optical and scanning electron microscope. Friction coefficients of composite and aluminum alloys at room temperature were similar except pure aluminum. As the temperature increase, friction coefficient was increased rapidly in AC4C, AC2A. But friction coefficient of $Al-SiC_{p}$ composite was not increased so much up to $220^{\circ}C$. Consequently, the reinforcement of $SiC_{p}$ into aluminum matrix increased the stability of friction coefficient as well as wear resistance.

알루미늄 분말 연소를 위한 고체 화학수소화물 기반 수소 점화 시스템 (Solid Chemical Hydride-Based Hydrogen Ignition System for Aluminum Powder Combustion)

  • 박길수;김태규
    • 한국추진공학회지
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    • 제23권3호
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    • pp.88-95
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    • 2019
  • 수소 토치 점화 시스템은 순수한 알루미늄을 이용하여 점화가 가능하고 점화 방법이 간단해 알루미늄 연소 시스템으로 많이 사용되고 있다. 하지만 기존의 수소 토치 점화 시스템은 수소 공급을 위해 고압의 수소탱크가 필요해 무게가 무거워지는 단점이 있다. 이러한 문제를 해결하기 위해 본 연구에서는 고체 화학수소화물인 $NaBH_4$를 이용한 수소 점화 시스템을 설계하였다. $NaBH_4$는 약 $500^{\circ}C$에서 열분해가 시작되고 수소가 발생한다. $NaBH_4$ 열분해 특성에 영향을 미치는 변인들을 분석하고, $NaBH_4$ 기반 수소 점화 시스템을 이용해 알루미늄 연소 실험을 수행하여 실제 시스템 적용 가능성에 대해 검증 하였다.

Preparation of Alumina Powder with Special Morphology

  • Ma, Chicheng;Zhou, Xuesi;Zhu, Tun
    • 한국결정성장학회:학술대회논문집
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    • 한국결정성장학회 1997년도 Proceedings of the 12th KACG Technical Meeting and the 4th Korea-Japan EMGS (Electronic Materials Growth Symposium)
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    • pp.3-5
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    • 1997
  • Synthesis of ammonium aluminum hydrogen carbonate(AAHC) via reaction of aluminum bicarbonate and aluminum salt and thermal decomposition is oner of the important processes for preparation of high pure and ultra fine alumina. Kato and coworkers[1] developed this process, at same time Von Erdos and Altorfe[2] found AAHC in the corrosive products of aluminum in the atmosphere of carbon dioxide and ammonia. Murase and Iga[3] synthesized acicular AAHC in a autoclave under 60 to 12$0^{\circ}C$ Hayashi[4] optimized the conditions for preparation of AAHC and alumina. Attemp has been made in this paper to reveal the conditions affect the morphology of the synthesized AAHC and the consequently produced alumina.

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알루미늄 기지에 알루미늄-알루미나 혼합분말을 이용한 고온플라즈마 열분사 코팅층의 밀착강도 향상기구 (Improvement of Adhesion Strength of High Temperature Plasma Coated Aluminum Substrate with Aluminum-Alumina Powder Mixture)

  • 박진수;이효룡;이범호;박준식
    • 한국재료학회지
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    • 제25권5호
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    • pp.226-232
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    • 2015
  • 본 연구에서는 손상된 알루미늄 금형의 복원을 위해 고온플라즈마 용사법을 이용하여 금형의 표면에 $Al/Al_2O_3$ 혼합분말을 용사한 후 코팅층과 모재의 증착강도에 대한 평가를 수행하였다. 증착강도의 평가는 분사노즐의 이동속도, 순수한 알루미늄 bond coat 층의 유무에 따라 평가되었으며, bond coat 층을 생성시키지 않았을 때, 코팅층의 두께는 열팽창에 의한 잔류인장응력의 감소를 위해 두껍지 않아야 하지만 일정두께 이상이 되어야 최대의 증착강도를 얻을 수 있음이 나타났다. 또한 순수한 알루미늄 bond coat 층은 내부 결함이 없는 응고된 금속이기 때문에 두께에 따른 증착강도의 영향을 그대로 받아 두께가 두꺼울수록 bond coat 층을 생성시키지 않은 시험편보다 증착강도가 매우 낮게 측정되었다. 반면, 가장 얇게 bond coating 된 시험편 Bc3(3회의 bond coating층과 분사건의 이동속도가 20 cm/sec인 시험편) 는 bond coating을 하지 않은 시험편 중 가장 높은 증착강도를 가지는 시험편 Wbc20(bond coating층이 없고 분사건의 이동속도가 20 cm/sec인 시험편)보다 약 2배 이상증착강도가 향상되었다. 따라서 금형의 복원시에 중간층의 형성이 반드시 필요하며, 이는 코팅층의 잔류 인장응력을 보완시키며 고인성의 순수한 알루미늄과 같은 코팅층과 유사한 층을 코팅하는 것이 필요한 것으로 사료된다.