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. 20 No. 5 (2013년 10월) 12건
1.
2013.10
구독 인증기관 무료, 개인회원 유료
In this paper, two kinds of advanced powder processing techniques Metal Injection Molding (MIM) and Direct Laser Forming (DLF) are introduced to fabricate complex shaped Ti alloy parts which are widely used for med- ical and aerospace applications. The MIM process is used to strengthen Ti-6Al-4V alloy compacts by addition of fine Mo, Fe or Cr powders. Enhanced tensile strength of 1030 MPa with 15.1% elongation was obtained by an addition of 4 mass%Cr because of the microstructural modification and also the solution strengthening in beta phase. However, their fatigue strength was lower compared to wrought materials, but was improved by HIP. Subsequently, the effect of feed- ing layer height (FLH) on the characteristics of the DLF compacts was investigated. In the case of 100 µm FLH, sur- face roughness was improved and nearly full density (99.8%) was obtained. Also, tensile strength of 1080 MPa was obtained, which is higher than the ASTM value.
4,000원
2.
2013.10
구독 인증기관 무료, 개인회원 유료
Recently, self-propagating high-temperature synthesis (SHS), related to metallic and ceramic powder inter- actions, has attracted huge interest from more and more researchers, because it can provide an attractive, energy-efficient approach to the synthesis of simple and complex materials. The adiabatic temperature Tad and apparent activation energy analysis of different thermit systems plays an important role in thermodynamic studies on combustion synthesis. After establishing and verifying a mathematic calculation program for predicting adiabatic temperatures, based on the thermo- dynamic theory of combustion synthesis systems, the adiabatic temperatures of the NiO/Al aluminothermic system dur- ing self-propagating high-temperature synthesis were investigated. The effect of a diluting agent additive fraction on combustion velocity was studied. According to the simulation and experimental results, the apparent activation energy was estimated using the Arrhenius diagram of ln(v/Tad)~1/Tad based on the combustion equation given by Merzhanov et al. When the temperature exceeds the boiling point of aluminum (2,790 K), the apparent activation energy of the NiO/ Al aluminothermic system is 64 ± 14 kJ/mol. In contrast, below 2,790 K, the apparent activation energy is 189 ± 15 kJ/ mol. The process of combustion contributed to the mass-transference of aluminum reactant of the burning compacts. The reliability of the simulation results was experimentally verified.
4,000원
3.
2013.10
구독 인증기관 무료, 개인회원 유료
Fe-TiC composite was fabricated from Fe and TiC powders by high-energy milling and subsequent spark- plasma sintering. The microstructure, particle size and phase of Fe-TiC composite powders were investigated by field emission scanning electron microscopy and X-ray diffraction to evaluate the effect of milling conditions on the size and distribution of TiC particles in Fe matrix. TiC particle size decreased with milling time. The average TiC particle size of 38 nm was obtained after 60 minutes of milling at 1000 rpm. Prepared Fe-TiC powder mixture was densified by spark- plasma sintering. Sintered Fe-TiC compacts showed a relative density of 91.7~96.2%. The average TiC particle size of 150 nm was observed from the FE-SEM image. The microstructure, densification behavior, Vickers hardness, and frac- ture toughness of Fe-TiC sintered compact were investigated.
4,000원
4.
2013.10
구독 인증기관 무료, 개인회원 유료
Carbon nanotube-dispersed bismuth telluride matrix (CNT/Bi2Te3) nanopowders were synthesized by chem- ical routes followed by a ball-milling process. The microstructures of the synthesized CNT/Bi2Te3 nanopowders showed the characteristic microstructure of CNTs dispersed among disc-shaped Bi2Te3 nanopowders with as an average size of 500 nm in-plane and a few tens of nm in thickness. The prepared nanopowders were sintered into composites with a homogeneous dispersion of CNTs in a Bi2Te3 matrix. The dimensionless figure-of-merit of the composite showed an enhanced value compared to that of pure Bi2Te3 at the room temperature due to the reduced thermal conductivity and increased electrical conductivity with the addition of CNTs.
4,000원
5.
2013.10
구독 인증기관 무료, 개인회원 유료
In this study, porous titanium samples were manufactured by space holder methods using two kinds of urea and sodium chloride space holders. Three-dimensional pore structures were obtained by a computed-tomography (CT) tech- nique and utilized for finite element analysis in order to investigate the mechanical properties. The CT-based finite ele- ment analyses were in better agreement with the experimental results than unit cell model-based analyses. Both the experimental and CT-based results showed the same tendency that the elastic modulus decreased with increasing the porosities. The total porosity of the bulk body plays a key role in determining the elastic modulus of porous materials.
4,000원
6.
2013.10
구독 인증기관 무료, 개인회원 유료
Micro trench structures are applied in gratings, security films, wave guides, and micro fluidics. These micro trench structures have commonly been fabricated by micro electro mechanical system (MEMS) process. However, if the micro trench structures are machined using a diamond tool on large area plate, the resulting process is the most effective man- ufacturing method for products with high quality surfaces and outstanding optical characteristics. A nonferrous metal has been used as a workpiece; recently, and hybrid materials, including polymer materials, have been applied to mold for display fields. Thus, the machining characteristics of polymer materials should be analyzed. In this study, machining characteristics were compared between nonferrous metals and polymer materials using single crystal diamond (SCD) tools; the use of such materials is increasing in machining applications. The experiment was conducted using a square type diamond tool and a shaper machine tool with cutting depths of 2, 4, 6 and 10 µm and a cutting speed of 200 mm/s. The machined surfaces, chip, and cutting force were compared through the experiment.
3,000원
7.
2013.10
구독 인증기관 무료, 개인회원 유료
In this study, we fabricated Nd2Fe14B hard magnetic powders with various sizes via spray drying combined with reduction-diffusion process. Spray drying is widely used to produce nearly spherical particles that are relatively homogeneous. Thus, the precursor particles were prepared by spray drying using the aqueous solution containing Nd salts, Fe salts and boric acid with the target stoichiometric composition of Nd2Fe14B. The mean particle sizes of the spray-dried powders are in the range from one to seven micrometer, which are adjusted by controlling the concentra- tions of precursor solutions. After debinding the as-prepared precursor particles, ball milling was also conducted to con- trol the particle sizes of Nd-Fe-B oxide powders. The resulting particles with different sizes were subjected to subsequent treatments including hydrogen reduction, Ca reduction and washing for CaO removal. The size effect of Nd-Fe-B oxide particles on the formation of Nd2Fe14B phase and magnetic properties was investigated.
4,200원
8.
2013.10
구독 인증기관 무료, 개인회원 유료
The effects of B4C on the mechanical properties of WC/Ni-Si hardmetal were analyzed using sintered bod- ies comprising WC(70-x wt.%), Ni (28.5 wt.%), Si (1.5 wt.%), and B4C (x wt.%), where 0 x 1.2 wt.%. Samples were prepared by a combination of mechanical milling and liquid-phase sintering. Phase and microstructure character- izations were conducted using X-ray diffractometry, scanning electron microscopy, and electron probe X-ray micro anal- ysis. The mechanical properties of the sintered bodies were evaluated by measuring their hardness and transverse rupture strength. The addition of B4C improved the sinterability of the hardmetals. With increasing B4C content, their hardness increased, but their transverse rupture strength decreased. The changes of sinterability and mechanical properties were attributed to the alloying reaction between B4C and the binder metal (Ni, Si). ≤ ≤
4,000원
9.
2013.10
구독 인증기관 무료, 개인회원 유료
ZnO nanoparticles in the size range from 5 to 15 nm were prepared by zinc-lithium-acetate system. The morphologies and structures of ZnO were characterized by TEM, XRD and FT-IR spectra. UV-visible results shows that the absorption of ZnO nanoparticles is blue shifted with decrease in particles size. Furthermore, photoluminescence spectra of the ZnO nanoparticles were also investigated. The ZnO nanoparticles have strong visible-emission intensity and their intensities depend upon size of ZnO nanoparticles.
4,000원
10.
2013.10
구독 인증기관 무료, 개인회원 유료
Spherical Ti-6Al-4V powders in the size range of 250 and 300 µm were uniformly doped with nano-sized hydroxyapatite (HAp) powders by Spex milling process. A single pulse of 0.75-2.0 kJ/0.7 g of the Ti-6Al-4V powders doped with HAp from 300 mF capacitor was applied to produce fully porous and porous-surfaced Ti-6Al-4V implant compact by electro-discharge-sintering (EDS). The solid core was automatically formed in the center of the compact after discharge and porous layer consisted of particles connected in three dimensions by necks. The solid core increased with an increase in input energy. The compressive yield strength was in a range of 41 to 215 MPa and significantly depended on input energy. X-ray photoelectron spectroscopy and energy dispersive x-ray spectrometer were used to investigate the surface characteristics of the Ti-6Al-4V compact. Ti and O were the main constituents, with smaller amount of Ca and P. It was thus concluded that the porous-surfaced Ti-6Al-4V implant compacts doped with HAp can be efficiently produced by manipulating the milling and electro-discharge-sintering processes.
4,000원
11.
2013.10
구독 인증기관 무료, 개인회원 유료
4,000원
12.
2013.10
구독 인증기관 무료, 개인회원 유료
4,000원
