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. 11 No. 2 (2004년 4월) 14건
1.
2004.04
구독 인증기관 무료, 개인회원 유료
1980년대 후반부터 집중적으로 연구되어온 기계적 합금화 공정 기술은 이제 단순화합물 조성의 합금화공정 뿐 만아니라 기계화학적(Mechanochemical) 방법으로까지 진보되어 다양한 시스템으로의 응용기술로까지 발전하게 되었다 더욱이 최근 나노기술의 한고상 제조기술로서도 역할을 하게 되는 기계적 합금화 공정 기술은 21세기에 있어서도 본문에서 연급한 바와 같은 고온용 고장도 Al 합금제조 외에도 나노결정립 분말, 자성재료, 에너지전환/저장기능재료, 준
4,000원
2.
2004.04
구독 인증기관 무료, 개인회원 유료
In this paper processing and mechanical properties of Al-20 wt％ Si alloy was studied. A bulk form of Al-20Si alloy was prepared by gas atomizing powders having the powder size of 106-145 and powder extrusion. The powder extrudate was subsequently equal channel angular pressed up to 8 passes in order to refine grain and Si particle. The microstructure of the gas atomized powders, powder extrudates and equal channel angular pressed samples were investigated using a scanning electron microscope and X-ray diffraction. The mechanical properties of the bulk sample were measured by compressive tests and a micro Victors hardness test. Equal channel angular pressing was found to be effective in matrix grain and Si particle refinement, which enhanced the strength and hardness of the Al-2OSi alloy without deteriorating ductility in the range of experimental strain of 30％.
4,000원
3.
2004.04
구독 인증기관 무료, 개인회원 유료
In this study the possibility to obtain a homogeneous mixture and to produce solid solutions and intermetallic compounds of Fe and Al nano particles by simultaneous pulsed wire evaporation (S-PWE) have been investigated. The Fe and Al wires with 0.45 mm in diameter and 35 mm in length were continuously co-fed by a special mechanism to the explosion chamber and simultaneously exploded. The characteristics, e.g., phase composition, particle shape, and specific surface area of Fe-Al nano powders have been analyzed. The synthesized powders, beside for Al and -Fe, contain significant amount of a high-temperature phase of -Fe, Fe Al and traces of other intermetallics. The phase composition of powders could be changed over broad limits by varying initial explosion conditions, e.g. wire distance, input energy, for parallel wires of different metals. The yield of the nano powder is as large as 40 wt ％ and the powder may include up to 46 wt % FeAl as an intermetallic compound.
4,000원
4.
2004.04
구독 인증기관 무료, 개인회원 유료
The oxidation behavior of 91 WC-9Co hardmetal in weight percentage has been studied in the present work as a part of the development of recycling process. The morphological and compositional changes of the WC-Co hardmetal with oxidation time at 90 were analyzed by using surface observation and X-ray diffraction. respective]y. As the oxidation time increased, the WC-Co hardmetal was continuously expanded to form porous oxide mixtures of and . The morphology of porous oxide mixture was basically dependent on initial shape of the WC-Co hardmetal. From thermo-gravimetric (TG) analysis, it was found that the oxidation rate was increased with increasing oxidation temperature and oxygen content in the flowing atmospheric gas. The fraction of oxidation versus time curves showed S-curve relationship at a given of oxidation temperature. These oxidation behaviors of the WC-Co hardmetal were discussed in terms of previously proposed kinetic models.
4,000원
5.
2004.04
구독 인증기관 무료, 개인회원 유료
A formation of aluminum hydroxide by hydrolysis reaction in the water has been studied by using nano aluminum powder fabricated by pulsed wire evaporation(PWE) method. The hydroxide type and morphology depending on temperature and pH were examined by structural analysis. The Boehmite(. or AIO(OH)) was predominantly formed in high temperature region over 4, while the Bayerite(. or ) below of hydrolysis temperature. The Boehmite formation was preferred to the Bayerite in acidic solution in the same hydrolysis temperature. The slowly formed Bayerite phase showed facet crystalline structure, while the fast formed Boehmite was fine fiber with a large aspect ratio of several nm in diameter and several hundred nm in length, and with much larger specific surface area(SSA) than that of Bayerite. The highest SSA was about /g.
4,000원
6.
2004.04
구독 인증기관 무료, 개인회원 유료
Nanosized WC and WC-Co powders were synthesised by chemical vapor condensation(CVC) process using the pyrolysis of tungsten hexacarbonyl(W(CO)) and cobalt octacarbonyl(Co(CO)). The microstructural changes and phase evolution of the CVC powders during post heat-treatment were studied using the XRD, FE-SEM, TEM, and ICP-MS. CVC powders were consisted of the loosely agglomerated sub-stoichimetric WC and the long-chain Co nanopowders. The sub-stochiometric CVC WC and WC-Co powders were carburized using the mixture gas of CH-H in the temperature range of 730-85. Carbon content of CVC powder controlled by the gas phase carburization at 85 was well matched with the theoretical carbon sioichiometry of WC, 6.13 wt％. During the gas phase carburization, the particle size of WC increased from 20 nm to 40 nm and the long chain structure of Co powders disappeared.
4,000원
7.
2004.04
구독 인증기관 무료, 개인회원 유료
The passivation and oxidation process of tungsten and molybdenum narlopowders, produced by electrical explosion of wires was studied by means of FE-SEM, XPS. XRD, TEM, DIA-TGA and sire distribution analysis. In addition, the phase transformation of W and Mo nanopowders under oxidation in air was investigated. A chemical process is suggested for the oxidation of W and Mo nano-particles after a comprehensive testing of passivated and oxidized powders.
4,000원
8.
2004.04
구독 인증기관 무료, 개인회원 유료
In this study, chemical solution mixing and hydrogen reduction method was used to fabricate nanostructured alloy powders. Fe-Co chloride mixture, FeCl and COCI with 99.9％ purity, were reduced in hydrogen atmosphere. Nanostructured Fe-Co alloy powders with a grain size of 50 nm were successfully fabricated. Magnetic properties of fabricated (x=0, 10, 30, 50, 70, 100) alloy powders with the same grain size were measured because size factor can affect magnetic properties. Coercivity of Fe-Co alloy powders were increased with increasing Co contents. Maximum value of coercivity in various Co contented Fe-Co alloy powders with similar grain size was 125 Oe at Fe. Saturation magnetization value at FeCo composition showed maximum value of 219 emu/g and saturation magnetization value decreased with increasing Co contents and minimum value of 155 emu/g was observed at Co.
4,000원
9.
2004.04
구독 인증기관 무료, 개인회원 유료
In the present study, imbedded composite powders have been successfully prepared from the (Cu. Zn)/ composite salt solution. The composite (Cu, Zn)/ powders were formed by drying the solution at 200~ in the hydrogen atmosphere. Photocatalytic characteristics was evaluated by detecting the decomposition ratio of aniline blue with UV-visible spectrophotometer(Shimazu Co., UV-1601). Phase analysis of (Cu, Zn)/ composite powders was carried out by XRD and DSC, and powder size was measured with TEM. The mean particle size of composite powders was about 100mm. As the reduction temperature increases, a few zinc sulfide and oxide phases was formed and copper oxide phase was reduced. The decomposition ratio of aniline blue was about 80％ under the UV irradiation by the TiO phase in the composite (Cu, Zn)/ powders and similar decomposition ratio of 80％ was obtained at the UV lightless condition by virtue of Cu and Zn compounds.
4,000원
10.
2004.04
구독 인증기관 무료, 개인회원 유료
High temperature deformation behavior of activated sintered W powder compacts was investigated. The compression tests were carried out in the temperature range between 900 and 110 at the strain rate of . The sintered specimens of Ni-doped submicron W powder compacts showed decrease in W grain size with increasing the Ni content. As the result, the flow stress was significantly increased with increasing the Ni content. We obtained Ni-activated sintered W compacts with the relative density of 94 l％and the average grain size of less than 5. A moderate true strain up to 0.60 was obtained without fracture even at 110 with the strain rate of for the activated W compact despite adding the 1.0 wt％Ni to submicron W powder.
4,000원
11.
2004.04
구독 인증기관 무료, 개인회원 유료
W-Cu composite has been used for the applications requiring both high strength, good thermal and electrical conductivity. A graded combination of W and Cu will reduce thermal stress concerned with heat conduction, maintaining good thermal conductivity and high mechanical strength. In the present work, an attempt was made to fabricate continuous W-Cu FGM by preparing the graded porous structure of W skeleton using spark plasma sintering (SPS) process followed by infiltrating Cu. The graded porous structure was prepared at 150 for 60s under pressure of 15MPa by SPS process using a graphite mold with varying crr)ss section in the longitudinal direction. Infiltration of Cu was performed at 115 for 1 hour under . W-Cu composite with graded Cu composition of 14 to 27 wt％ was finally prepared. In this process the gradient of composition could be conveniently controlled by varying the gradient of cross sectional area of graphite mold, temperature and pressure.
4,000원
12.
2004.04
구독 인증기관 무료, 개인회원 유료
Growth behavior of two different types of grains, faceted and rounded, in a liquid matrix has been studied in the (75WC-25TiCN)-30Co system. Powder samples were sintered above the eutectic temperature for various times under a carbon saturated condition. (Ti,W)(C,N) grains with a rounded shape and WC grains with a faceted shape coexisted in the same Co based liquid. With increasing sintering time, the average size of (Ti.W)(C,N) grains increased continuously and very large WC grains appeared. The growth of rounded (Ti,W)(C,N) grains followed a cubic law, =kt, where r is the average size of the grains, the initial average size, k the proportionality constant and t the sintering time. indicating a diffusion-controlled growth. On the other hand, the growth of the faceted WC grains resulted in a bimodal grain size distribution, showing an abnormal grain growth. These observations show that the growth behavior of different types of grains is governed by their shape, faceted or rounded, even in the same liquid matrix.
4,000원
13.
2004.04
구독 인증기관 무료, 개인회원 유료
Effects of liquid phase and reinforcing particle morphology on the sintering of Al-6 wt％Cu-10 vol％ or SiC particles were studied in regards to densification, structure and transverse rupture properties. The Al-Cu liquid phase penetrated the boundaries between the aluminum matrix powders and the interfaces with reinforcing particles as well, indicating a good wettability to the powders. This enhanced the densification during sintering and the resulting strength and ductility. Since most of the copper added, however, was dissolved in the liquid phase and formed a brittle phase upon cooling rather than alloyed with the aluminum matrix, the strengthening effect by the copper was not fully realized. Reinforcing particles of agglomerate type were found less suitable for the liquid phase sintering than solid type particles. and SiC particles protluced little difference on the sintering behavior but their size had a large effect. Repressing of the sintered composites increased density and bending properties but caused debonding at the matrix-particle interfaces and also fracturing of the particles.
4,000원
14.
2004.04
구독 인증기관 무료, 개인회원 유료
통상적인 금속분말의 성형은 분말야금 공정으로 이루어지기 때문에 복잡한 형상의 부품을 구현하는 데는 제약이 있다. 하지만, 1970년대 후반 이래 새로운 금속분말의 성형기술로 크게 각광을 받으며 연구되고 있는 금속분말사출성형(Metal Powder Injection Molding, MIM) 기술을 이용하면 다양한 형태의 부품을 성형할 수 있다 최근에는 이러한 MIM 기술을 이용하여 다양한 산업분야에 응용될 수 있는 마이크로 부품을 제조하고자 하는 연구개발
4,000원
