간행물
한국분말야금학회지 KCI 등재 Journal of Korean Powder Metallurgy Institute
- 발행기관 한국분말재료학회(구 한국분말야금학회)
- 자료유형 학술지
- 간기 격월간
- ISSN 1225-7591 (Print)2287-8173 (Online)
- 수록기간 1994 ~ 2024
- 주제분류 공학 > 금속공학 공학 분류의 다른 간행물
- 십진분류KDC 559DDC 629
권호리스트/논문검색
Vol. 21 No. 1 (2014년 2월) 11건
1.
2014.02
구독 인증기관 무료, 개인회원 유료
Medical technologies are gaining in importance because of scientific and technical progress in medicine andthe increasing average lifetime of people. This has opened up a huge market for medical devices, where complex-shapedmetallic parts made from biocompatible materials are in great demand. Today many of these components are alreadybeing manufactured by powder metallurgy technologies. This includes mass production of standard products and alsocustomized components. In this paper some aspects related to metal injection molding of Ti and its alloys as well asmodifications of microstructure and surface finish were discussed. The process chain of additive manufacturing (AM)was described and the current state of the art of AM processes like Selective Laser Melting and electron beam meltingfor medical applications was presented.
4,000원
2.
2014.02
구독 인증기관 무료, 개인회원 유료
This study investigated the densification behavior of rhenium alloys including W-25 wt.%Re and Re-2W-1Ta (pure Re) during sintering. The dilatometry experiments were carried out to obtain the in-situ shrinkage in H2 atmo-sphere. The measured data was analyzed through shrinkage, strain rate and relative density, and then symmetricallytreated to construct the linearized form of master sintering curve (MSC) and MSC as a well-known and straightforwardapproach to describe the densification behavior during sintering. The densification behaviors for each material were ana-lyzed in many respects including apparent activation energy, densification parameter, and densification ratio. MSC witha minimal set of preliminary experiments can make the densification behavior to be characterized and predicted as wellas provide guideline to sinter cycle design. Considering the results of linearized form and MSC, it was confirmed thatthe W-25 wt.%Re compared to Pure Re is more easily densified at the relatively low temperature.
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3.
2014.02
구독 인증기관 무료, 개인회원 유료
In order to fabricate the porous Al₂O₃ with dispersion of nano-sized Cu particles, freeze-drying of cam-phene/Al₂O₃ slurry and solution chemistry process using Cu-nitrate are introduced. Camphene slurries with 10vol% Al₂O₃ was frozen at -25˚C. Pores were generated by sublimation of the camphene during drying in air. The sinteredsamples at 1400 and 1500oC showed the same size of large pores which were aligned parallel to the sublimable vehiclesgrowth direction. However, the size of fine pores in the internal walls of large pores decreased with increase in sinteringtemperature. It was shown that Cu particles with the size of 100 nm were homogeneously dispersed on the surfaces ofthe large pores. Antibacterial test using fungus revealed that the porous Al₂O₃/1vol% Cu composite showed antifungalproperty due to the dispersion of Cu particles. The results are suggested that the porous composites with required porecharacteristics and functional property can be fabricated by freeze-drying process and addition of functional nano par-ticles by chemical method.
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4.
2014.02
구독 인증기관 무료, 개인회원 유료
In this study, diatomite based materials were investigated as a support filter for silica particle coating. Thesilica sol for coating was synthesized by a stöber process. The diatomite support was dry-pressed at 10 MPa and sin-tered at 1200˚C for 1 hour. The coating sol was prepared as a mixture of EtOH and silica sol. The diatomite supportwas coated by a dip-coating process. Silica coated diatomite filter was sintered at 1000~1200˚C for 1 hour. The largestpore size was decreased with increasing concentration ratio of coating sol. The gas and water permeability of silicacoated diatomite decreased with increasing of concentration ratio of the coating sol.
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5.
2014.02
구독 인증기관 무료, 개인회원 유료
This paper describes the surface modification effect of a Ti substrate for improved dispersibility of the cat-alytic metal. Etching of a pure titanium substrate was conducted in 50% H₂SO₄, 50˚C for 1h-12h to observe the sur-face roughness as a function of the etching time. At 1h, the grain boundaries were obvious and the crystal grains weredistinguishable. The grain surface showed micro-porosities owing to the formation of micro-pits less than 1 µm in diam-eter. The depths of the grain boundary and micro-pits appear to increase with etching time. After synthesizing the cat-alytic metal and growing the carbon nano tube (CNT) on Ti substrate with varying surface roughness, the distributiontrends of the catalytic metal and grown CNT on Ti substrate are discussed from a micro-structural perspective.
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6.
2014.02
구독 인증기관 무료, 개인회원 유료
Cu-Ni alloys with unidirectionally aligned pores were prepared by freeze-drying process of CuO-NiO/cam-phene slurry. Camphene slurries with dispersion stability by the addition of oligomeric polyester were frozen at -25˚C,and pores in the frozen specimens were generated by sublimation of the camphene during drying in air. The green bod-ies were hydrogen-reduced at 300˚C and sintered at 850˚C for 1h. X-ray diffraction analysis revealed that CuO-NiOcomposite powders were completely converted to Cu-Ni alloy without any reaction phases by hydrogen reduction. Thesintered samples showed large and aligned parallel pores to the camphene growth direction, and small pores in the inter-nal wall of large pores. The pore size and porosity decreased with increase in CuO-NiO content from 5 to 10 vol%.The change of pore characteristics was explained by the degree of powder rearrangement in slurry and the accumulationbehavior of powders in the interdendritic spaces of solidified camphene.
4,000원
7.
2014.02
구독 인증기관 무료, 개인회원 유료
Bulk nanostructured copper was fabricated by a shock compaction method using the planar shock wavegenerated by a single gas gun system. Nano sized powders, average diameter of 100 nm, were compacted into the cap-sule and target die, which were designed to eliminate the effect of undesired shock wave, and then impacted with analuminum alloy target at 400 m/s. Microstructure and mechanical properties of the shock compact specimen were ana-lyzed using an optical microscope (OM), scanning electron microscope (SEM), and micro indentation. Hardness resultsshowed low values (approximately 45~80 Hv) similar or slightly higher than those of conventional coarse grained com-mercial purity copper. This result indicates the poor quality of bonding between particles. Images from OM and SEMalso confirmed that no strong bonding was achieved between them due to the insufficient energy and surface oxygenlayer of the powders.
4,000원
8.
2014.02
구독 인증기관 무료, 개인회원 유료
In this study, nanocrystalline nickel powders were cold compacted by a dynamic compaction method usinga single-stage gas gun system. A bending test was conducted to measure the bonding strengths of the compacted regionsand microstructures of the specimen were analyzed using a scanning electron microscopy. The specimen was separatedinto two parts by a horizontal crack after compaction. Density test shows that the powder compaction occurred only inthe upper part of the specimen. Brittle fracture was occurred during the bending test of the compact sample. Dispersionof shock energy due to spalling highly affected the bonding status of the nanocrystalline nickel powder.
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9.
2014.02
구독 인증기관 무료, 개인회원 유료
A powder-in-sheath rolling method was applied to a fabrication of a carbon nano tube (CNT) reinforcedaluminum composite. A STS304 tube with an outer diameter of 34 mm and a wall thickness of 2 mm was used as asheath material. A mixture of pure aluminum powders and CNTs with the volume contents of 1, 3, 5 vol was filled inthe 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 exhib-ited high value more than 98. The grain size of the aluminum matrix was largely decreased with addition of CNTs; itdecreased from 24 µm to 0.9 µm by the addition of only 1 volCNT. The average hardness of the composites increasedby approximately 3 times with the addition of CNTs, comparing to that of unreinforced pure aluminum. It is concludedthat the powder-in-sheath rolling method is an effective process for fabrication of CNT reinforced Al matrix composites.
4,000원
10.
2014.02
구독 인증기관 무료, 개인회원 유료
Fe-Cr-Al powder porous metal was manufactured by using new electro-spray process. First, ultra-finefecralloy powders were produced by using the submerged electric wire explosion process. Evenly distributed colloid(0.05~0.5% powders) was dispersed on Polyurethane foam through the electro-spray process. And then degreasing andsintering processes were conduced. In order to examine the effect of cell size (200 µm, 450 µm, 500 µm) in process,pre-samples were sintered for two hours at temperature of 1450˚C, in H₂ atmospheres. A 24-hour thermo gravimetricanalysis test was conducted at 1000˚C in a 79% N₂ + 21% O₂ to investigate the high temperature oxidation behavior ofpowder porous metal. The results of the high temperature oxidation tests showed that oxidation resistance increased withincreasing cell size. In the 200 µm porous metal with a thinner strut and larger specific surface area, the depletion ofthe stabilizing elements such as Al and Cr occurred more quickly during the high-temperature oxidation compared withthe 450, 500 µm porous metals.
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PM Trend
11.
2014.02
구독 인증기관 무료, 개인회원 유료
4,000원
