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Tytuł:
Effect Of Heat-Treatment On Microstructure And Magnetic Properties Of Nanocrystallized Mn-Zn Ferrite Powders
Wpływ obróbki cieplnej na mikrostrukturę i właściwości magnetyczne nanokrystalicznych proszków ferrytu Mn-Zn
Autorzy:
Lee, W. H.
Hong, C. S.
Chang, S. Y.
Powiązania:
https://bibliotekanauki.pl/articles/351552.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high energy ball milling
nanosized particles
crystallite size
magnetic properties
frezowanie kulowe
nanocząstki
wielkości krystalitów
właściwości magnetyczne
Opis:
The initial ferrite powders were subjected to high energy ball milling at 300rpm for 3h, and subsequently heat-treated at 573-1273K for 1h. Based on the observation of microstructure and measurement of magnetic properties, the heat-treatment effect was investigated. The size of initial powders was approximately 70μm. After milling, the powders with approximately 230nm in size were obtained, which were composed of the nano-sized particles of approximately 15nm in size. The milled powders became larger to approximately 550nm after heat-treatment at 973K. In addition, the size of particles increased to approximately 120nm with increasing temperature up to 973K. The coercivity of initial powders was almost unchanged after milling, whereas the saturation magnetization increased. As the heat-treatment temperature increased, the saturation magnetization gradually increased and the maximum coercivity was obtained at 773K.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1347-1350
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Finitely based monoids obtained from non-finitely based semigroups
Autorzy:
Lee, Edmond W. H.
Powiązania:
https://bibliotekanauki.pl/articles/1368164.pdf
Data publikacji:
2013
Wydawca:
Uniwersytet Jagielloński. Wydawnictwo Uniwersytetu Jagiellońskiego
Opis:
Presently, no example of non-finitely based finite semigroup $S$ is known for which the monoid $S^1$ is finitely based. Based on a general result of M. V. Volkov, two methods are established from which examples of such semigroups can be constructed.
Źródło:
Universitatis Iagellonicae Acta Mathematica; 2013, 51; 45-49
2084-3828
0083-4386
Pojawia się w:
Universitatis Iagellonicae Acta Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spontaneous Formation of Titanium Nitride on the Surface of a Ti Rod Induced by Electro-Discharge-Heat-Treatment in an N2 Atmosphere
Autorzy:
Lee, W. H.
Yoon, Y. H.
Kim, Y. H.
Lee, Y. K.
Kim, J. Y.
Chang, S. Y.
Powiązania:
https://bibliotekanauki.pl/articles/352477.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
titanium
surface modification
diffusion
heat treatment
XPS
Opis:
A single pulse of 2.0 to 3.5 kJ of input energy from a 450 mF capacitor was applied to a commercially pure Ti rod in a N2 atmosphere. The surface of the Ti rod transformed from TiO2 into titanium nitride in times as short as 159 msec, providing a bimodal morphology of the cross-section. A much higher value of hardness that was observed at the edge of the cross-section was attributed to nitrogen-induced solid-solution hardening that occurred during the electrical discharge process. The activation energy (Ea) for the diffusion process was estimated to be approximately 86.9 kJ/mol. Results show that the electrical discharge process is a possible potential method for the nitriding of Ti; advantages include a short processing time and control of the nitrided layer without dimensional changes.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1281-1285
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Self-Consolidation Mechanism of Ti5Si3 Compact Obtained by Electro-Discharge-Sintering Directly from Physically Blended Ti-37.5 At.% Si Powder Mixture
Autorzy:
Chang, S. Y.
Cheon, Y. W.
Yoon, Y. H.
Kim, Y. H.
Kim, J. Y.
Lee, Y. K.
Lee, W. H.
Powiązania:
https://bibliotekanauki.pl/articles/353022.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
sintering
mechanical alloying
powder consolidation
intermetallic compounds
titanium silicide
Opis:
Characteristics of electro-discharge-sintering of the Ti-37.5at.% Si powder mixture was investigated as a function of the input energy, capacitance, and discharge time without applying any external pressure. A solid bulk of Ti5Si3 was obtained only after in less than 129 μsec by the EDS process. During a discharge, the heat is generated to liquefy and alloy the particles, and which enhances the pinch pressure can condensate them without allowing a formation of pores. Three step processes for the self-consolidation mechanism during EDS are proposed; (a) a physical breakdown of oxide film on elemental as-received powder particles, (b) alloying and densifying the consolidation of powder particles by the pinch pressure, and (c) diffusion of impurities into the consolidated surface.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1299-1302
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Self-Consolidation and Surface Modification of Mechanical Alloyed Ti-25.0 at.% Al Powder Mixture by Using an Electro-Discharge Technique
Autorzy:
Chang, S. Y.
Jang, H. S.
Yoon, Y. H.
Kim, Y. H.
Kim, J. Y.
Lee, Y. K.
Lee, W. H.
Powiązania:
https://bibliotekanauki.pl/articles/354212.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
sintering
mechanical alloying
powder consolidation
intermetallic compounds
titanium aluminides
Opis:
Electrical discharges using a capacitance of 450 μF at 0.5, 1.0, and 1.5 kJ input energies were applied in a N2 atmosphere to obtain the mechanical alloyed Ti3Al powder without applying any external pressure. A solid bulk of nanostructured Ti3Al was obtained as short as 160 μsec by the Electrical discharge. At the same time, the surface has been modified into the form of Ti and Al nitrides due to the diffusion process of nitrogen to the surface. The input energy was found to be the most important parameter to affect the formation of a solid core and surface chemistry of the compact.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1293-1297
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Self-Consolidation Mechanism Of Porous Ti-6Al-4V Implant Prototypes Produced By Electro-Discharge-Sintering Of Spherical Ti-6Al-4V Powders
Mechanizm autokonsolidacji prototypów porowatych implantów wytworzonych przez spiekanie sferycznych proszków Ti-6Al-4V
Autorzy:
Lee, W. H.
Jo, Y. J.
Kim, Y. H.
Jo, Y. H.
Seong, J. G.
Van Tyne, C. J.
Chang, S. Y.
Powiązania:
https://bibliotekanauki.pl/articles/356277.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Ti-6Al-4V
implant
porous
sintering
electrodischarge
porowatość
spiekanie
proszki spiekane
Opis:
Electro-Discharge-Sintering (EDS) was employed to fabricate Ti-6Al-4V porous implant prototypes from atomized powders (100 – 150 μm), that were subjected to discharges of 0.75 to 2.0 kJ/0.7g-powder from 150, 300, and 450 μF capacitors. Both fully porous and porous-surfaced Ti-6Al-4V compacts with various solid core sizes were self-consolidated in less than 86 – 155 μsec. It is known that EDS can simultaneously produce the pinch pressure to squeeze and deform powder particles and the heat to weld them together. The formation of a solid core in these prototypes depends on the amounts of both the pinch pressure and heat generated during a discharge. The size of the solid core and the thickness of the porous layer can be successfully controlled by manipulating the discharge conditions such as input energy and capacitance.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1185-1189
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Surface Modification of Self-Consolidated Microporous Ti Implant Compacts Fabricated by Electro-Discharge-Sintering in Air
Autorzy:
Jo, Y. J.
Yoon, Y. H.
Kim, Y. H.
Chang, S. Y.
Kim, J. Y.
Lee, Y. K.
Van Tyne, C. J.
Lee, W. H.
Powiązania:
https://bibliotekanauki.pl/articles/356790.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
titanium
implant
porous
sintering
X-ray photoelectron spectroscopy (XPS)
Opis:
A single pulse of 0.75-2.0 kJ/0.7g of atomized spherical Ti powders from 300 mF capacitor was applied to produce a microporous Ti implant compact by electro-discharge-sintering (EDS). A solid core in the middle of the compact surrounded by a microporous layer was found. X-ray photoelectron spectroscopy was employed to study the surface characteristics of the EDS Ti compact and it revealed that Ti, C and O were the main constituents on the surface with a smaller amount of N. The surface was lightly oxidized and was primarily in the form of TiO2 resulting from the air oxidation during EDS processing. The lightly oxidized surface of the EDS compact also exhibited Ti nitrides such as TiN and TiON, which revealed that the reaction between air constituents and the Ti powders even in times as short as 128 msec.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1287-1291
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Compositional Dependence of Hardness of Ge-Sb-Se Glass for Molded Lens Applications
Zależność stężeniowa twardości szkła Ge-Sb-Se do zastosowań na formowane soczewki
Autorzy:
Park, J. K.
Lee, J. H.
Shin, S. Y.
Yi, J. H.
Lee, W. H.
Park, B. J.
Choi, J. H.
Kim, N. Y.
Choi, Y. G.
Powiązania:
https://bibliotekanauki.pl/articles/352228.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
chalcogenide glasses
Ge-Sb-Se glass
infrared lens
molded lens
infrared camera
szkło
Ge-Sb-Se
soczewki formowane
twardość szkła
kamera termowizyjna
Opis:
Chalcogenide glass in the ternary Ge-Sb-Se system is inherently moldable, thus being considered as a strong candidate material for use in infrared-transmitting lens applications from the viewpoint of thermal and mechanical stability. In an effort to experimentally determine compositional region suitable for the molded lens applications, we evaluate its compositional dependence of hardness. Among the constituent atoms, Ge content turns out to exert a most conspicuous correlation with hardness. This phenomenological behavior is then explained in connection with the structural evolution that Ge brings about.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1205-1208
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure and Magnetic Properties of NdFeB Sintered Magnets Diffusion-Treated with Cu/Al Mixed Dyco Alloy-Powder
Autorzy:
Lee, M.-W.
Bae, K.-H.
Lee, S.-R.
Kim, H.-J.
Jang, T.-S.
Powiązania:
https://bibliotekanauki.pl/articles/353351.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Nd-Fe-B sintered magnets
grain boundary diffusion process
low melting point element
DyCo alloy-powder diffusion
Opis:
We investigated the microstructural and magnetic property changes of DyCo, Cu + DyCo, and Al + DyCo diffusion-treated NdFeB sintered magnets. The coercivity of all diffusion treated magnet was increased at 880ºC of 1st post annealing(PA), by 6.1 kOe in Cu and 7.0 kOe in Al mixed DyCo coated magnets, whereas this increment was found to be relatively low (3.9 kOe) in the magnet coated with DyCo only. The diffusivity and diffusion depth of Dy were increased in those magnets which were treated with Cu or Al mixed DyCo, mainly due to comparatively easy diffusion path provided by Cu and Al because of their solubility with Ndrich grain boundary phase. The formation of Cu/Al-rich grain boundary phase might have enhanced the diffusivity of Dy-atoms. Moreover, relatively a large number of Dy atoms reached into the magnet and mostly segregated at the interface of Nd2 Fe14 B and grain boundary phases covering Nd2 Fe14 B grains so that the core-shell type structures were developed. The formation of highly anisotropic (Nd, Dy)2Fe14B phase layer, which acted as the shell in the core-shell type structure so as to prevent the reverse domain movement, was the cause of enhancing the coercivity of diffusion treated NdFeB magnets. Segregation of cobalt in Nd-rich TJP followed by the formation of Co-rich phase was beneficial for the coercivity enhancement, resulting in the stabilization of the metastable c-Nd2O3 phase.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1263-1266
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characteristics Of The Porous Body Sintered By Nano-Sized Fe-Cr-Al Alloy Powder
Charakterystyka porowatego korpusu spiekanego z nanometrycznego proszku stopu Fe-Cr-Al
Autorzy:
Lee, S.-I.
Lee, S.-H.
Gu, B.-U.
Lee, D.-W.
Kim, B.-K.
Powiązania:
https://bibliotekanauki.pl/articles/356635.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Fe-Cr-Al powder
metallic sponges
sintering temperature
oxidation resistance
proszek Fe-Cr-Al
proszek nanometryczny
temperatura spiekania
odporność na utlenianie
Opis:
Porous metal with uniform honeycomb structure was successfully produced by sintering using Fe-Cr-Al nano powder, which was prepared by the pulsed wire evaporation (PWE) in ethanol. Its process consisted of the several steps; 1) coating on the surface of polyurethane sponge with the liquid droplets generated from the ethanol-based slurry where the Fe-Cr-Al nano powders were uniformly dispersed, 2) heat treatment of debinding to remove the polyurethane sponge and 3) sintering of the porous green body formed by Fe-Cr-Al nano powders. The strut thickness of porous Fe-Cr-Al was increased by the increase of spraying times in ESP step. Also, The shrinkages and the oxidation resistance of the sintered porous body was increased with increase of sintering temperature. The optimal sintering temperature was shown to 1450°C in views to maximize the oxidation resistance and sinterability.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1275-1279
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of a high-speed air bearing spindle
Autorzy:
Ha, Y.-H.
Lee, D.-W.
Hwang, Y.-K.
Lee, C.-M.
Powiązania:
https://bibliotekanauki.pl/articles/1429126.pdf
Data publikacji:
2008
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
aerostatic bearing
metal foam
porous thrust bearing
porous radial bearing
Opis:
This paper investigates an air spindle with both radial and thrust air bearings of newly developing one-directional porous materials. At present, orifice type and porous type are adopted for thrust air bearings. Orifice type thrust air bearing is fabricated by machining several micro-holes on a bearing pad bearing, permeability significantly affected by particle size and machining conditions is an important factor of performance, but it is hard to c porosities is suggested. It has many micro-porosities through axial direction, so stable and plenty of air can be supplied to the thrust bearing pad. A radial air bearing also can be substituted by a radial direction porous bearing as the same reason. In case of driving parts, built-in motor type is widely applied. But it needs additional cooling parts to drop heat from a motor. So application of an air turbine drive with light-weight shaft is suggested and additionally it will reduce fabricating cost.
Źródło:
Journal of Machine Engineering; 2008, 8, 4; 25-31
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Empirical Investigation of the Influence of Safety Climate on Organizational Citizenship Behavior in Taiwan’s Facilities
Autorzy:
Lee, T. Z.
Wu, C. H.
Hong, C. W.
Powiązania:
https://bibliotekanauki.pl/articles/91216.pdf
Data publikacji:
2007
Wydawca:
Centralny Instytut Ochrony Pracy
Tematy:
safety climate
organizational citizenship behavior
social exchange relationship
psychological effect
Opis:
Although the social exchange relationships between employers and employees are increasingly important to the performance of safety management systems, the psychological effects of work attitudes on this relationship have been less studied. Using a sample of first-line operators and their supervisors from 188 facilities in Taiwan which had Occupational Health and Safety Assessment Series 18000 (OHSAS 18000) certification, the current research conducted an empirical investigation of the influence of safety climate on organizational citizenship behavior (OCB). Work attitude was used to disclose the psychological effect. Research results indicated that (a) safety climate was a significant predicator of OCB, (b) the psychological effect significantly influenced social exchange relationships, and (c) job satisfaction showed a stronger mediating influence than organizational commitment due to the frequent top management turnover. Discussions and implications are also addressed.
Źródło:
International Journal of Occupational Safety and Ergonomics; 2007, 13, 3; 255--269
1080-3548
Pojawia się w:
International Journal of Occupational Safety and Ergonomics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effects Of Environmental Factors On The Dispersion Behavior Of Iron Oxide In Aqueous Solutions With Poly Acrylic Acid
Wpływ parametrów charakteryzujących wodne roztwory poli(kwasu akrylowego) na dyspersję tlenku żelaza
Autorzy:
Lee, E.-H.
Kim, K.-M.
Maeng, W.-Y.
Hur, D.-H.
Powiązania:
https://bibliotekanauki.pl/articles/354513.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
polyacrylic acid
dispersion stability
magnetite
nanoparticles
suspension
poli(kwas akrylowy)
stabilność dyspersji
magnetyt
nanocząstki
zawiesina
Opis:
After preparing aqueous suspensions from magnetite particles with a poly-acrylic acid, we investigated the effects of several experimental parameters. We characterized the stability of the suspensions using visual inspection, sedimentation, adsorption, and thermal stability of the dispersant. The dispersion stability is affected by the solution pH, the concentrations of magnetite particles, the molecular weight, the concentration of the dispersants, and the temperature. The stability of the suspensions increased as the concentration of the dispersant and the temperature increased. In terms of the molecular weights of the dispersant, the suspensions with dispersant of low-molecular weight (1800) were more stable than those of high-molecular weight (250000) at room temperature. However, at high temperature the suspensions with high-molecular weight showed stability. The adsorption efficiency of the dispersant was very low. The dispersant of high-molecular weight showed a higher thermal integrity than that of low-molecular weight. From this work, we obtained the optimum conditions for stable aqueous suspensions of magnetite particles.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1561-1564
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Oxide Formation In Metal Injection Molding Of 316L Stainless Steel
Tworzenie tlenków podczas wtryskiwania proszku stali nierdzewnej 316L
Autorzy:
Jang, J. M.
Lee, W.
Ko, S.-H.
Han, C.
Choi, H.
Powiązania:
https://bibliotekanauki.pl/articles/351352.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
powder injection molding
sintering
316L stainless steel
sintering atmosphere
micro parts
wtryskiwanie proszku
spiekanie
stal nierdzewna 316L
mikro-część
Opis:
The effects of sintering condition and powder size on the microstructure of MIMed parts were investigated using water-atomized 316L stainless steel powder. The 316L stainless steel feedstock was injected into micro mold with micro features of various shapes and dimensions. The green parts were debound and pre-sintered at 800°C in hydrogen atmosphere and then sintered at 1300°C and 1350°C in argon atmosphere of 5torr and 760torr, respectively. The oxide particles were formed and distributed homogeneously inside the sample except for the outermost region regardless of sintering condition and powder size. The width of layer without oxide particles are increased with decrease of sintering atmosphere pressure and powder size. The fine oxides act as the obstacle on grain growth and the high sintering temperature causes severe grain growth in micro features due to larger amount of heat gain than that in macro ones.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1281-1285
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Development of a shape memory alloy wire actuator to operate a morphing wing
Autorzy:
Rim, M.
Kim, E.-H.
Kang, W.-R.
Lee, I.
Powiązania:
https://bibliotekanauki.pl/articles/280828.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Mechaniki Teoretycznej i Stosowanej
Tematy:
morphing wing
shape memory alloy (SMA)
wire actuator
Opis:
DSC tests were performed on several types of SMAs to verify the phase-transformation temperatures, and then experiments to examine their characteristics were carried out. An electric-current was supplied to the SMA wire to measure the appropriate operational cur- rent range. The force generated by the SMA wire increased according to the supplied current, but it diminished when the over-current was supplied because thermo-mechanical properties of the wire started to degrade. The appropriate stress range for effective actuation charac- teristics was also investigated. The SMA wire actuator was designed to operate a morphing wing. Experiments for the wing were conducted to verify its characteristics and it was smo- othly deformed.
Źródło:
Journal of Theoretical and Applied Mechanics; 2014, 52, 2; 519-531
1429-2955
Pojawia się w:
Journal of Theoretical and Applied Mechanics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect Of DyMn Alloy-Powder Addition On Microstructure And Magnetic Properties Of NdFeB Sintered Magnets
Wpływ dodatku proszku DyMn na mikrostrukturę i właściwości magnetyczne spiekanych magnesów NdFeB
Autorzy:
Lee, M.-W.
Dhakal, D. R.
Kim, T. H.
Lee, S. R.
Kim, H. J.
Jang, T. S.
Powiązania:
https://bibliotekanauki.pl/articles/357010.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Nd-Fe-B sintered magnets
DyMn-alloy powder
coercivity
low melting point element
magnesy spiekane
proszek DyMn
koercja
elementy o niskiej temperaturze topnienia
Opis:
Micostructural change and corresponding effect on coercivity of a NdFeB sintered magnet mixed with small amount of DyMn powder was investigated. In the sintered magnet mixed with the DyMn alloy-powder Dy-rich shell was formed at outer layer of the main grains, while Mn was mostly concentrated at Nd-rich triple junction phase (TJP), lowering melting temperature of the Nd-rich phase that eventually improved the microstructural characteristics of the gain boundary phase. The coercivity of a magnet increased more than 3.5 kOe by the mixing of the DyMn alloy-powder.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1407-1409
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Double Step Sintering Behavior Of 316L Nanoparticle Dispersed Micro-Sphere Powder
Dwuetapowe spiekanie mikrosferycznych nanocząstek proszku 316L
Autorzy:
Jeon, B.
Sohn, S. H.
Lee, W.
Han, C.
Kim, Y. D.
Choi, H.
Powiązania:
https://bibliotekanauki.pl/articles/355221.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
316L stainless steel
nanoparticle dispersed micro-sphere
pulse wire explosion
sintering
stal nierdzewna 316L
spiekanie dwuetapowe
mikrosferyczne nanocząstki
Opis:
316L stainless steel is a well-established engineering material and lots of components are fabricated by either ingot metallurgy or powder metallurgy. From the viewpoints of material properties and process versatility, powder metallurgy has been widely applied in industries. Generally, stainless steel powders are prepared by atomization processes and powder characteristics, compaction ability, and sinterability are quite different according to the powder preparation process. In the present study, a nanoparticle dispersed micro-sphere powder is synthesized by pulse wire explosion of 316L stainless steel wire in order to facilitate compaction ability and sintering ability. Nanoparticles which are deposited on the surface of micro-powder are advantageous for a rigid die compaction while spherical micro-powder is not to be compacted. Additionally, double step sintering behavior is observed for the powder in the dilatometry of cylindrical compact body. Earlier shrinkage peak comes from the sintering of nanoparticle and later one results from the micro-powder sintering. Microstructure as well as phase composition of the sintered body is investigated.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1155-1158
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Finite element analysis of three-point bending of a T-beam structural biaxial highly oriented polymer material
Analiza metodą elementów skończonych zginania trójpunktowego belki teowej wykonanej z wysoko zorientowanego dwuosiowo materiału polimerowego
Autorzy:
Wei, C.-L.
Chang, Y.
Lee, Y.-C.
Lee, R.
Luo, T.-W.
Chen, J.-H.
Powiązania:
https://bibliotekanauki.pl/articles/946988.pdf
Data publikacji:
2018
Wydawca:
Sieć Badawcza Łukasiewicz - Instytut Chemii Przemysłowej
Tematy:
solid phase processing
highly oriented polymer (HOP)
orthotropic materials
T-beam
three-point bending
finite element
proces w fazie stałej
wysoko zorientowany polimer
materiały ortotropowe
belka teowa
zginanie trójpunktowe
elementy skończone
Opis:
Polymers with biaxial aligned molecular chains are also orthotropic materials, which are characterized by high tensile strength and low shear strength in the length direction. When orthotropic materials are used as structural shapes with poor shear strength, they are likely to undergo premature failure under shear stress. Therefore, in three-point bending, the cross-section of the entire profile not only bears tensile stress and compressive stress in the length direction, but also simultaneously exhibits shear stress. This study analyzes the distribution of tensile stress, compressive stress and shear stress in the length direction of highly oriented polymers (HOP) by finite element analysis to find the most suitable length-to-height ratio for these materials when used as structural shapes. The finite element analysis software, Abaqus, is utilized to simulate HOP T-beam to analyze the load stress of a T-beam. With a fixed cross–section area, as the length of the material changes, its shear strength also changes. Accordingly, the order of occurrence of tensile failure and shear failure can be investigated. The simulation reveals that when the length-to-height ratio is between 4 : 1 and 20 : 1, a zone of stress in which tensile failure and shear failure occur can be found. This result can be exploited in the design and development of structural beam.
Polimery o dwuosiowo zorientowanych łańcuchach makrocząsteczek są materiałami ortotropowymi, wykazującymi dużą wytrzymałość na rozciąganie oraz niewielką wytrzymałość na ścinanie w kierunku długości. Elementy konstrukcyjne wytworzone z materiału ortotropowego o małej wytrzymałości na ścinanie są podatne na przedwczesne uszkodzenie pod wpływem naprężeń ścinających. Przy zginaniu trójpunktowym w przekroju ich profilu występują zarówno naprężenia rozciągające i ściskające w kierunku podłużnym, jak i naprężenia ścinające. Metodą elementów skończonych analizowano rozkład naprężeń rozciągających, ściskających i ścinających w kierunku podłużnym wysoko zorientowanych polimerów (HOP) w celu określenia optymalnego stosunku długości do wysokości w kształtach konstrukcyjnych. Do symulacji naprężeń obciążeniowych w zginaniu trójpunktowym belki teowej wykorzystano program komputerowy Abaqus. Stwierdzono, że przy stałej powierzchni przekroju poprzecznego belki jej wytrzymałość na ścinanie zmienia się wraz ze zmianą długości. Badano również kolejność występowania uszkodzeń pod wpływem działania sił rozciągających i ścinających. Symulacja wykazała, że przy stosunku długości do wysokości w zakresie od 4 : 1 do 20 : 1 występuje strefa naprężeń, w której mogą się pojawiać uszkodzenia w wyniku rozciągania lub ścinania. Uzyskane wyniki można wykorzystać w projektowaniu i optymalizacji belek konstrukcyjnych.
Źródło:
Polimery; 2018, 63, 3; 219-223
0032-2725
Pojawia się w:
Polimery
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect Of The Desorption-Recombination Temperature On The Microstructure And Magnetic Properties Of HDDR Processed Nd-Fe-B Powders
Wpływ temperatury desorpcji-rekombinacji na mikrostrukturę i właściwości magnetyczne proszków Nd-Fe-B przetwarzanych metodą HDDR
Autorzy:
Lee, J.-G.
Cha, H.-R.
Liu, S.
Yu, J.-H.
Baek, Y.-K.
Kwon, H.-W.
Powiązania:
https://bibliotekanauki.pl/articles/353723.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Nd-Fe-B
HDDR
permanent magnet
grain boundary
metoda HDDR
magnes trwały
granica ziarna
Opis:
The effect of the desorption-recombination temperature on the microstructure and magnetic properties of hydrogenation-disproportionation-desorption-recombination (HDDR) processed Nd-Fe-B powders was studied. The NdxB6.4Ga0.3Nb20.2Febal (x=12.5-13.5, at.%) casting alloys were pulverized after homogenizing annealing, and then subjected to HDDR treatment. During the HDDR process, desorption-recombination (DR) reaction was induced at two different temperature, 810°C and 820°C. The higher Nd content resulted in enhanced coercivity of the HDDR powder, and which was attributed to the thicker and more uniform Nd-rich phase along grain boundaries. But this uniform Nd-rich phase induced faster grain growth. The remanence of the powder DR-treated at 820°C is higher than that DR-treated at 810°C. In addition, it was also confirmed that higher DR temperature is much more effective to improve squareness.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1499-1501
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Reduced expression of AURKA in peripheral blood of breast cancer patients
Autorzy:
Goh, L.P.W.
See, E.U.H.
Chua, K.H.
Lee, P.-C.
Powiązania:
https://bibliotekanauki.pl/articles/81279.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
breast cancer
patient
Aurora kinase
gene expression
peripheral blood
cell cycle
quantitative real-time polymerase chain reaction
Źródło:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology; 2018, 99, 1
0860-7796
Pojawia się w:
BioTechnologia. Journal of Biotechnology Computational Biology and Bionanotechnology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High-temperature Oxidation Behavior and Kinetics of Forged 12Cr-MoVW Steel
Autorzy:
Kim, Y. H.
Oak, J.-J.
Bae, K.-C.
Lee, W-J.
Park, Y. H.
Powiązania:
https://bibliotekanauki.pl/articles/351450.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
ferritic/martensitic stainless steels
forging
oxidation kinetics
oxide layer
Opis:
The oxidation kinetics of forged 12Cr-MoVW steel was investigated in an air (N2+O2) atmosphere at 873-1073 K (Δ50 K) using thermogravimetric analysis. The oxidized samples were characterized using X-ray diffraction, and the surface and cross-sectional morphologies were examined using scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy. The forged 12Cr-MoVW steel samples exhibited parabolic behavior and a low oxidation rate compared with their as-cast counterparts. A protective oxide layer was uniformly formed at relatively low temperature (≤973 K) for the forged samples, which thus exhibited better oxidation resistance than the as-cast ones. These oxides are considered solid-solution compounds such as (Fe, Cr)2O3.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1099-1104
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication and Characterization of CoCrFeNiMn High Entropy Alloy Powder Processed by Gas Atomization
Autorzy:
Park, T. G.
Lee, S. H.
Lee, B.
Cho, H. M.
Choi, W. J.
Kim, B. S.
Shin, K. S.
Kim, T.-S.
Powiązania:
https://bibliotekanauki.pl/articles/353649.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high entropy alloy
gas atomization
spark plasma sintering
CoCrFeNiMn
Opis:
In this study, precisely controlled large scale gas atomization process was applied to produce spherical and uniform shaped high entropy alloy powder. The gas atomization process was carried out to fabricate CoCrFeNiMn alloy, which was studied for high ductility and mechanical properties at low temperatures. It was confirmed that the mass scale, single phase, equiatomic, and high purity spherical high entropy alloy powder was produced by gas atomization process. The powder was sintered by spark plasma sintering process with various sintering conditions, and mechanical properties were characterized. Through this research, we have developed a mass production process of high quality and spherical high entropy alloy powder, and it is expected to expand applications of this high entropy alloy into fields such as powder injection molding and 3D printing for complex shaped components.
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 2; 1055-1059
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Study On The Electro-Refining Of Tin In Acid Solution From Electronic Waste
Badanie elektrorafinacji cyny w roztworze kwasu z e-odpadów
Autorzy:
Son, S. H.
Park, S. C.
Kim, J. H.
Kim, Y. H.
Lee, M. S.
Ahn, J.-W.
Powiązania:
https://bibliotekanauki.pl/articles/352665.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
electrorefining
tin
electronic waste
recycling
high purity
elektrorafinacja
cyna
odpady elektroniczne
recykling
Opis:
The tin metal could be retractable from wasted tin scrap, sludge, and wasted electroplated solution hydrometallurgical treatment, and purification process. In order to be used as resource of electronic devices, the retracted crude metal should be purified to the extent of higher than 99.9%. In this study, tin electro-refining process was performed to purify the casted tin crude metal at various experimental conditions: at the current density of 3, 5A/dm2, and in various electrolytes such as hydrochloric acid, sulfuric acid and methansulfonic acid. Additional experiment was conducted using Rotating Disk Electrode (RDE) in order to investigate the rate determining step of tin electro-refining process. The current efficiency, 65.6%, was achievable at the condition of current density, 5A/dm2, and in the electrolyte of Hydrochloric acid. During tin electro-refining process, impurity dissolved from tin crude metal into the electrolyte was analyzed using Inductively Coupled Plasma Optical Emission Spectrometer (ICP-OES), and the result showed the concentration of impurity metal gradually increased. Quantitative analysis on casted tin crude metal showed that it consists of tin with 93.9 wt.% and several impurity metals of Ag, Bi, Pb, Cu, and etc. After tin electro-refining process, the purity of tin increased up to 99.985 wt.%.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1217-1220
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication of AZ31/CNT Surface Nano-composite by Double-pass Friction Stir Processing
Autorzy:
Kim, J. Y.
Hwang, J.-W.
Kim, H. Y.
Lee, S. M.
Jung, W.-S.
Byeon, J.-W.
Powiązania:
https://bibliotekanauki.pl/articles/355624.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
surface modification
Double-pass Friction Stir Processing
AZ31
composite
CNT
Opis:
Double-pass Friction Stir Processing (FSP) was applied to fabricate an AZ31/CNT nano-composite for surface hardening of lightweight structural components. The effects of double-pass FSP as well as groove depth (i.e., volume fraction of CNT) on the CNT distribution, dynamically recrystallized grain size, and resulting microhardness were studied. Double-pass FSP was performed for the CNT-filled plate-type specimen with different groove depths of 2, 3, and 4 mm. By applying double-pass FSP, the average size of CNT clusters decreased, implying a more homogeneous distribution. Compared with the FSPed specimen without CNT, grain size was refined from 19 μm to 3 μm and microhardness increased from 52 Hv to 83 Hv (i.e., 71% increase).
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1039-1042
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preparation Of Fine Grained SiC At Reduced Temperature By Two-Step Sintering
Wytwarzanie drobnoziarnistego SiC w obniżonej temperaturze przez dwuetapowe spiekanie
Autorzy:
Kim, K.-W.
Oh, K.-S.
Lee, H.
Kim, B. S.
Chung, T.-J.
Powiązania:
https://bibliotekanauki.pl/articles/353772.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
SiC
liquid phase
two step sintering
coarsening
hardness
faza ciekła
spiekanie dwuetapowe
odporność
twardość
Opis:
Two-step sintering route was applied for the densification SiC by promoting the role of liquid phase. The specimen contained 8 vol% of liquid phase composed of Al2O3 and Y2O3. The heating schedule consisted with initial rapid heating to 2000°C and immediate quenching to 1700 or 1750°C. By heating at elevated temperature, even distribution of the liquid phase was intended. The heat treatment at reduced temperature was to suppress the evaporative loss of the liquid and to secure the time for densification. The two-step sintering effectively suppressed loss of mass and coarsening. The resultant SiC was thus dense and was composed of fine grains exhibiting hardness of 2321 kgf/mm2.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1539-1542
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
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