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분말시스압연법에 의한 5 vol%CNT/Al 복합재료의 제조 및 평가
홍동민,김우진,이성희,Hong, Dongmin,Kim, Woo-Jin,Lee, Seong-Hee 한국재료학회 2013 한국재료학회지 Vol.23 No.11
A powder in sheath rolling method was applied to the fabrication of a carbon nano tube (CNT) reinforced aluminum composite. A 6061 aluminum alloy tube with outer diameter of 31 mm and wall thickness of 2 mm was used as a sheath material. A mixture of pure aluminum powder and CNTs with a volume content of 5% was filled in the tube by tap filling and then processed to an 85% reduction using multi-pass rolling after heating for 0.5 h at $400^{\circ}C$. The specimen was then further processed at $400^{\circ}C$ by multi-pass hot rolling. The specimen was then annealed for 1 h at various temperatures that ranged from 100 to $500^{\circ}C$. The relative density of the 5vol%CNT/Al composite fabricated using powder in sheath rolling increased with increasing of the rolling reduction, becoming about 97% after hot rolling under 96 % total reduction. The relative density of the composite hardly changed regardless of the increasing of the annealing temperature. The average hardness also had only slight dependence on the annealing temperature. However, the tensile strength of the composite containing the 6061 aluminum sheath decreased and the fracture elongation increased with increasing of the annealing temperature. It is concluded that the powder in sheath rolling method is an effective process for fabrication of CNT reinforced Al matrix composites.
분말시스압연법에 의한 CNT 강화 Al기 복합재료의 제조 및 평가
이성희,홍동민,Lee, Seong-Hee,Hong, Dongmin 한국분말야금학회 2014 한국분말재료학회지 (KPMI) Vol.21 No.1
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.
축류압축기 익형 Stacking 방식변화가 후단 입구유동에 미치는 영향
이성룡(Sungryong Lee),송재욱(Jaewook Song),홍동민(Dongmin Hong),이창용(Changyong Lee),김수용(Sooyong Kim) 대한기계학회 2009 대한기계학회 춘추학술대회 Vol.2009 No.5
This paper presents design and CFD analysis of a transonic compressor rotor with various sweep. The rotor was used to investigate the influence of sweep on performance and stability of a single stage transonic compressor numerically compared with a baseline design with radially stacked blade sections by 3D Navier-Stokes code. It was found that the new rotor with sweep has an increased efficiency and also a much better stall margin which is mainly caused by moving the separation position on the suction surface of rotor blade to the downstream direction.