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Wyświetlanie 1-20 z 20
Tytuł:
Investigation of Localized Electric Field in the Type-II InAs/GaAsSb/GaAs Structure
Autorzy:
Lee, S.
Kim, J.
Yoon, S.
Kim, Y.
Honsberg, C.
Powiązania:
https://bibliotekanauki.pl/articles/1398577.pdf
Data publikacji:
2016-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.66.Fd
78.40.-q
73.40.Lq
73.50.Pz
Opis:
The effect of localized electric field (F) was investigated in the type-II InAs/GaAsSb/GaAs structures. To compare type-I to type-II, two types of samples with different Sb contents was grown by molecular beam epitaxy, whose Sb contents are 3% (type-I) and 16% (type-II), respectively. In the both samples, we performed excitation power dependent-photoreflectance at 10 K and the result showed that the period of the Franz-Keldysh oscillation, revealed above the band gap $(E_{g})$ of GaAs, was broadened in the only type-II system, which means that F was also increased because it is proportional to the period of the Franz-Keldysh oscillation while the period of the Franz-Keldysh oscillations stayed unchanged in type-I system. This phenomenon is explained by that the F was affected by the band bending effect caused by the spatially separated photo-excited carriers in the interface between GaAsSb and GaAs. The F changed linearly as a function of square root of excitation power as expected for the F. Moreover, F was calculated using fast Fourier transform method for a qualitative analysis, which is in a good agreement with the theory of triangular well approximation.
Źródło:
Acta Physica Polonica A; 2016, 130, 5; 1213-1216
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of the Microstructure and Thermoelectric Properties of P-Type BiSbTe Alloys by Usage of Different Revolutions Per Minute (RPM) During Mechanical Milling
Autorzy:
Yoon, S.-M.
Madavali, B.
Yoon, Y.-N.
Hong, S.-J.
Powiązania:
https://bibliotekanauki.pl/articles/354749.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Bi0.5Sb1.5Te3 alloys
mechanical alloying
spark plasma sintering
thermoelectric properties
Opis:
In this work, p-type Bi0.5Sb1.5Te3 alloys were fabricated by high-energy ball milling (MA) and spark plasma sintering. Different revolutions per minute (RPM)s were used in the MA process, and their effect on microstructure, and thermoelectric properties of p-type Bi0.5Sb1.5Te3 were systematically investigated. The crystal structure of milled powders and sintered samples were characterized using X-ray diffraction. All the powders exhibited the same morphology albeit with slight differences find at 1100 RPM conditions. A slight grain size refinement was observed on the fracture surfaces from 500 to 1100 RPM specimens. The temperature dependence of Seebeck coefficient, electrical conductivity, and power factors were measured as a function of temperature with different RPM conditions. The power factor shows almost same (~3.5 W/mK2 at RT) for all samples due to unchanged Seebeck and electrical conductivity values. The peak ZT of 1.07 at 375K is obtained for 1100 RPM specimen due to low thermal conductivity.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1167-1171
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Zabezpieczenie transformatorów olejowych przed wybuchem: eksperymenty i symulacje
Protection of oil-filled transformers against explosion: experiments and simulations
Autorzy:
Landis, B.
Muller, S.
Perigaud, G.
Petrovan-Boiarciuc, M.
Ahmed, O. K.
Yoon, S.
Powiązania:
https://bibliotekanauki.pl/articles/153693.pdf
Data publikacji:
2013
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
transformatory energetyczne
eksplozja
łuk elektryczny
eksperymenty
symulacje
power transformers
explosion
electrical arc
experiments
simulations
Opis:
Eksplozje transformatorów olejowych są powodowane przez łuk elektryczy. W przeciągu milisekund łuk doprowadza do odparowania otaczającego go oleju a wygenerowany gaz znajduje się pod ciśnieniem ponieważ inercja oleju zapobiega jego ekspansji. To doprowadza do niebezpiecznych eksplozji, kosztownych awarii i ewentualnego zanieczyszczenia środowiska. Podczas gdy mury ochronne otaczające transformator mogą zahamować eksplozje a tryskacze zagasić wywołany pożar niniejszy dokument przedstawia strategię, która zapobiega eksplozji kadzi transformatora.
Oil-filled transformer explosions are caused by electrical arc occurring in transformer tanks. Within milliseconds, arc vaporizes the surrounding oil and the generated gas is pressurized as the liquid inertia prevents its expansion. The pressure difference between the gas bubble and the surrounding oil generates pressure waves, which propagate and interact with the tank. The reflections of the pressure waves build up the static pressure, which rises and leads to the tank rupture since tanks are not designed to withstand such levels of static pressure. This results in dangerous explosions, expensive damages and possible environmental pollution. The current paper presents a strategy to prevent the transformer tank rupture. Once an electrical fault occurs, the fast depressurization of the tank is induced by quick oil evacuation to a reservoir in order to prevent the tank explosion. To evaluate the efficiency of this strategy, experiments and computer simulations are used. The experiments were performed on large scale transformers equipped with the protection. They confirmed that the protection prevents the explosion. Besides, simulations of the consequences of an electrical arc occurring in a 200 MVA transformer geometry were run and again, they confirmed that the static pressure increase can be prevented by a quick oil evacuation triggered by the first dynamic pressure peak generated by the electrical arc.
Źródło:
Pomiary Automatyka Kontrola; 2013, R. 59, nr 2, 2; 176-182
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Novel Extraction Process Of Rare Earth Elements From NdFeB Powders Via Alkaline Treatment
Nowy sposób ekstrakcji pierwiastków ziem rzadkich z proszków NdFeB w roztworach alkalicznych
Autorzy:
Chung, K. W.
Kim, C.-J.
Yoon, H.-S.
Powiązania:
https://bibliotekanauki.pl/articles/355324.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
recycling
NdFeB magnet
alkaline treatment
leaching
selective leaching efficiency
recykling
magnes neodymowy
obróbka alkaliczna
ługowanie
wydajność
Opis:
The alkaline treatment of NdFeB powders in NaOH solution at various equivalent amounts of NaOH at 100°C was performed. The resultant powders were then leached in 0.5M H2SO4 solution at 25°C for 2 minutes. At 5 equivalents of NaOH, neodymium in NdFeB powders was partially transformed to neodymium hydroxide. The transformation of neodymium to neodymium hydroxide actually occurred at 10 equivalents of NaOH and was facilitated by increasing the equivalent of NaOH from 10 to 30. In addition, iron was partially transformed to magnetite during the alkaline treatment, which was also promoted at a higher equivalent of NaOH. The leaching yield of neodymium from alkaline-treated powders was increased with an increasing equivalent of NaOH up to 10; however, it slightly decreased with the equivalent NaOH of over 10. The leaching yield of iron was inversely proportional to that of rare earth elements. NdFeB powders treated at 10 equivalents of NaOH showed a maximum leaching yield of neodymium and dysprosium of 91.6% and 94.6%, respectively, and the lowest leaching yield of iron of 24.2%, resulting in the highest selective leaching efficiency of 69.4%.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1301-1305
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect Of Carbon Nanotubes On The Properties Of Spark Plasma Sintered ZrO2/CNT Composites
Wpływ nanorurek węglowych na właściwości spiekanych metodą sps kompozytów ZrO2/CNT
Autorzy:
Shim, D. H.
Jung, S. S.
Kim, H. S.
Cho, H.
Kim, J. K.
Kim, T. G.
Yoon, S. J.
Powiązania:
https://bibliotekanauki.pl/articles/351266.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
CNT
ZrO2
composite
SPS
kompozyty
Opis:
Zirconia matrix ZrO2/CNT composite materials reinforced with multiwall carbon nanotubes were fabricated using a spark plasma sintering technique. The effects of the amount of CNTs addition, sintering temperature and sintering pressure on the properties of the resulting ZrO2/CNT composites were examined. 0 to 9 vol. % CNTs were dispersed in zirconia powder, and the resulting mixture was sintered. The electrical conductivity, hardness, flexural strength, and density were measured to characterize the composites. The friction and wear properties of the composites were also tested. The flexural strength and friction coefficient of the composites were improved with up to 6 vol.% of CNT addition and the flexural strength showed a close relationship with the relative density of the composite. The electrical conductivity increased with increasing proportion of the CNTs, but the efficiency was reduced at more than 6 vol.% CNTs.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1315-1318
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure and Compression Properties of Fe-Cr-B Alloy Manufactured using Laser Metal Deposition
Autorzy:
Joo, Y.-A.
Yoon, T.-S.
Park, S.-H.
Lee, K.-A.
Powiązania:
https://bibliotekanauki.pl/articles/352075.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Fe-Cr-B composite
laser Metal Deposition
bulk type
microstructure
compressive properties
Opis:
Fe-Cr-B alloy is a material with precipitation of boride inside Fe matrix, and it features outstanding hardness and wear resistance properties. However, Fe-Cr-B alloy is a difficult material to process, making it difficult to use as a bulk type structure material which requires delicate shapes. This study attempted to manufacture Fe-Cr-B alloy using a 3D printing process, laser metal deposition. This study also investigated the microstructure, hardness and compression properties of the manufactured alloy. Phase analysis results is confirmed that α-Fe phase as matrix and (Cr, Fe)2B phase as reinforcement phase. In the case of (Cr, Fe)2B phase, differences were observed according to the sample location. While long, coarse, unidirectional needle-type boride phases (~11 μm thickness) were observed in the center area of the sample, relatively finer boride phases (~6 μm thickness) in random directions were observed in other areas. At room temperature compression test results confirmed that the sample had a compression strength is approximately 2.1 GPa, proving that the sample is a material with extremely high strength. Observation of the compression fracture surface identified intergranular fractures in areas with needle-type boride, and transgranular fractures in areas with random borides. Based on this results, this study also reviewed the deformation behavior of LMD Fe-Cr-B alloy in relation to its microstructures.
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 3; 1459-1462
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Acid Dissolution Conditions on Recovery of Valuable Metals from Used Plasma Display Panel Scrap
Autorzy:
Kim, C.- M.
Dharmaiah, P.
Kim, H.-S.
Koo, J.-M.
Yoon, J.-S.
Hong, S.-H.
Hong, S.-J.
Powiązania:
https://bibliotekanauki.pl/articles/355713.pdf
Data publikacji:
2017
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
high energy ball milling
waste plasma display panels
dissolution
recovery
Opis:
The objective of this particular study was to recover valuable metals from waste plasma display panels using high energy ball milling with subsequent acid dissolution. Dissolution of milled (PDP) powder was studied in HCl, HNO3, and H2SO4 acidic solutions. The effects of dissolution acid, temperature, time, and PDP scrap powder to acid ratio on the leaching process were investigated and the most favorable conditions were found: (1) valuable metals (In, Ag, Mg) were recovered from PDP powder in a mixture of concentrated hydrochloric acid (HCl:H2O = 50:50); (2) the optimal dissolution temperature and time for the valuable metals were found to be 60°C and 30 min, respectively; (3) the ideal PDP scrap powder to acid solution ratio was found to be 1:10. The proposed method was applied to the recovery of magnesium, silver, and indium with satisfactory results.
Źródło:
Archives of Metallurgy and Materials; 2017, 62, 2B; 1173-1177
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Degradations of 2,4-dichlorophenol and polychlorinated biphenyls with zero valent iron under subcritical conditions. Importance of subcritical water oxidation
Autorzy:
Oh, S.-Y.
Yoon, M.-K.
Powiązania:
https://bibliotekanauki.pl/articles/207444.pdf
Data publikacji:
2015
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
chemicals removal
water treatment
degradation
gas chromatography
iron
mass spectrometry
organic pollutants
polychlorinated biphenyls
2,4-dichlorophenol
DCP
polychlorinated biphenyl
PCBs
usuwanie chemikaliów
uzdatnianie wody
degradacja
chromatografia gazowa
żelazo
spektrometria masowa
zanieczyszczenia organiczne
polichlorowane bifenyle
PCB
2,4-dichlorofenol
Opis:
The abiotic transformations of 2,4-dichlorophenol (DCP) and polychlorinated biphenyls (PCBs) has been examined in the presence and of zero valent iron (Fe(0)) under subcritical conditions. It was found that the degradation of DCP was significantly enhanced, showing complete degradation of DCP in 3 h at 300 °C. Control experiments without Fe(0) indicated that the removal of DCP in the iron–water system was mostly due to subcritical water oxidation and that the enhancement of degradation in the presence of Fe(0) was less significant. Regardless of Fe(0), PCBs were rapidly decomposed, showing 93% destruction in 5 h at 300 °C. Product identification by gas chromatography-mass spectrometry (GC-MS) analysis showed that the reductive transformation of DCP and PCBs w Fe(0) existed under subcritical conditions. Our results suggest that subcritical water degradation may be a possible remediation option to treat DCP and PCBs in water and soil.
Źródło:
Environment Protection Engineering; 2015, 41, 3; 73-86
0324-8828
Pojawia się w:
Environment Protection Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Simulated impacts of rainfall extremes on yield responses of various barley varieties in a temperate region
Autorzy:
Yoon, C.Y.
Kim, S.
An, K.N.
Powiązania:
https://bibliotekanauki.pl/articles/2083065.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Instytut Agrofizyki PAN
Tematy:
barley
rainfall
simulation
food cost
grain
yield
Opis:
As population rises, more people need to be fed. With increasing income, the potential exists for increases in the demand for cereals (i.e., barley). Since barley has a high level of tolerance to environmental stressors, this crop has been recommended as a potential crop for food security in marginal environments. In this study, a crop growth Agricultural Land Management Alternatives with Numerical Assessment Criteria model, was parameterized and used to simulate the yields of two barley types grown in a temperate environment at a latitude of 35°N. In order to apply this crop model to barley, 19 years of field data were used to model calibration and validation. As a result, the ALMANAC model accurately simulated yields for both barley types. The validated model was used to predict yields under three diverse seasonal rainfall scenarios associated with different patterns of the Central Pacific El Niño influence. According to the simulation results, excessively high seasonal rainfall decreased barley yields. Crop price and annual revenue of the two barley types were also evaluated using a non-linear regression model. For the malt type, the food price was higher with a higher rainfall, while naked barley had a higher revenue under the conditions of a lower rainfall.
Źródło:
International Agrophysics; 2021, 35, 2; 119-129
0236-8722
Pojawia się w:
International Agrophysics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Combined Effect of Zr and Si on Isothermal Oxidation of Ti
Autorzy:
Ha, S.-H.
Kim, B.-H.
Yoon, Y.-O.
Lim, H.-K.
Kim, S. K.
Powiązania:
https://bibliotekanauki.pl/articles/353260.pdf
Data publikacji:
2018
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Ti
Zr
Si
silicide
oxidation
Opis:
In this study, the combined effect of Zr and Si on isothermal oxidation of Ti for 25 and 50h at 820°C, which is the temperature related to exhaust valves operation, was investigated. Si addition into Ti-5mass%Zr alloy led to a distribution of silicide Ti5Si3 phase formed by a eutectic reaction. The Ti sample containing only Zr showed more retarded oxidation rate than Ti-6Al-4V, the most prevalent Ti alloy, at the same condition. However, while a simultaneous addition of Zr and Si resulted in greater increase of oxidation resistance. The oxide layer formed after the addition of Zr and Si comprised TiO2, ZrO2, and SiO2.
Źródło:
Archives of Metallurgy and Materials; 2018, 63, 3; 1493-1495
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Adaptive Predictive Control of a Distillation Column
Autorzy:
Yoon, T. W.
Yang, D. R.
Lee, K. S.
Kwon, Y. M.
Powiązania:
https://bibliotekanauki.pl/articles/908309.pdf
Data publikacji:
1999
Wydawca:
Uniwersytet Zielonogórski. Oficyna Wydawnicza
Tematy:
adaptacyjny układ sterowania
sterownik predykcyjny
adaptive control
multivariable predictive controller
distillation column
Opis:
Distillation processes reveal complicated multivariable nonlinear dynamics for which it is difficult to design a high-performance control system. This paper proposes an adaptive control scheme for a distillation column. The proposed adaptive system consists of a multivariable receding-horizon predictive controller using a transfer function model and a recursive least-squares (RLS) based estimator. Simulations show a consistent closed-loop performance despite the uncertain nonlinear characteristics of the distillation column.
Źródło:
International Journal of Applied Mathematics and Computer Science; 1999, 9, 1; 193-206
1641-876X
2083-8492
Pojawia się w:
International Journal of Applied Mathematics and Computer Science
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Correlation Between Superheated Liquid Fragility And Onset Temperature Of Crystallization For Al-Based Amorphous Alloys
Korelacja między krytycznymi parametrami cieczy i temperaturą początku krystalizacji dla amorficznych stopów na bazie Al
Autorzy:
Guo, J.
Hu, X.
Liu, J.
Feng, T.
Yoon, E. Y.
Kim, H. S.
Powiązania:
https://bibliotekanauki.pl/articles/353707.pdf
Data publikacji:
2015
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
superheated liquid fragility
onset temperature of crystallization
thermal stability
krytyczny parametr cieczy
temperatura początku krystalizacji
stabilność termiczna
Opis:
Amorphous alloys or metallic glasses have attracted significant interest in the materials science and engineering communities due to their unique physical, mechanical, and chemical properties. The viscous flow of amorphous alloys exhibiting high strain rate sensitivity and homogeneous deformation is considered to be an important characteristic in thermoplastic forming processes performed within the supercooled liquid region because it allows superplastic-like deformation behavior. Here, the correlation between the superheated liquid fragility, and the onset temperature of crystallization for Al-based alloys, is investigated. The activation energy for viscous flow of the liquid is also investigated. There is a negative correlation between the parameter of superheated liquid fragility and the onset temperature of crystallization in the same Al-based alloy system. The activation energy decreases as the onset temperature of crystallization increases. This indicates that the stability of a superheated liquid can affect the thermal stability of the amorphous alloy. It also means that a liquid with a large superheated liquid fragility, when rapidly solidified, forms an amorphous alloy with a low thermal stability.
Źródło:
Archives of Metallurgy and Materials; 2015, 60, 2B; 1543-1546
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:
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:
The effect of climatic conditions in successive plant growing seasons on the response of selected varieties of apple trees (Malus domestica Borkh.)
Autorzy:
Zydlik, Z.
Rutkowski, K.
Swierczynski, S.
Morkunas, I.
Yoon, H.-K.
Seo, J.-H.
Kang, K.-J.
Kleiber, T.
Powiązania:
https://bibliotekanauki.pl/articles/14872.pdf
Data publikacji:
2020
Wydawca:
Uniwersytet Warmińsko-Mazurski w Olsztynie / Polskie Towarzystwo Magnezologiczne im. Prof. Juliana Aleksandrowicza
Źródło:
Journal of Elementology; 2020, 25, 1
1644-2296
Pojawia się w:
Journal of Elementology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication and Characterization of GaN/Polymer Composite p-n Junction with PEDOT Nanoparticle Interface Layer
Autorzy:
Kim, M.
Jin, S.
Choi, H.
Kim, G.
Yim, K.
Kim, S.
Nam, G.
Yoon, H.
Kim, Y.
Lee, D.
Kim, Jin
Kim, Jong
Leem, J.
Powiązania:
https://bibliotekanauki.pl/articles/1505152.pdf
Data publikacji:
2011-06
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
73.61.Ey
81.15.Gh
Opis:
A heavily Si-doped GaN/polymer hybrid structure with p-type poly(3,4-ethylene-dioxythiophene):beta-1,3-glucan (PEDOT nanoparticle) interface layer has been fabricated. The Si-doped GaN thin film with carrier concentration of 1 × $10^{19} cm^{-3}$ was grown by metal-organic chemical vapor deposition. The PEDOT nanoparticle with various sizes ranging from 60 to 120 nm was synthesized via a miniemulsion polymerization process. The electrical conductivity of the PEDOT nanoparticle is less than 1.2 S/cm. The current-voltage (I-V) characteristic of the hybrid structure shows diode-like behavior. The I-V characteristic was examined in the framework of the thermionic emission model. The ideality factor of the structure without PEDOT nanoparticle interface layer is 12.9. However, the ideality factor of the hybrid structure with PEDOT nanoparticle interface layer is obtained as 1.9. The value of ideality factor is dramatically decreased by inserting the PEDOT nanoparticle interface layer.
Źródło:
Acta Physica Polonica A; 2011, 119, 6; 875-879
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
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:
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:
Warm Tensile Deformation Behavior and Constitutive Equation of Supersaturated Solid-Solutionized Al-9Mg Extruded Alloy
Autorzy:
Yang, Seung Y.
Kim, Bong H.
Lee, Da B.
Choi, Kweon H.
Kim, Nam S.
Ha, Seong H.
Yoon, Young O.
Lim, Hyun K.
Kim, Shae
Kim, Young J.
Powiązania:
https://bibliotekanauki.pl/articles/2048882.pdf
Data publikacji:
2021
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
aluminum alloy
Al-9Mg alloy
tensile test
constitutive equation
Opis:
In this paper, as a purpose to apply the supersaturated solid-solutionized Al-9Mg alloy to the structural sheet parts of automotive, tensile tests were conducted under the various conditions and a constitutive equation was derived from the tensile test results. Al-9Mg alloy was produced using a special Mg master alloy containing Al2Ca during the casting process and extruded into the sheet. In order to study the deformation behavior of Al-9Mg alloy in warm temperature forming environments, tensile tests were conducted under the temperature of 373 K-573 K and the strain rate of 0.001/s~0.1/s. in addition, by using the raw data obtained from tensile tests, a constitutive equation of the Al-9Mg alloy was derived for predicting the optimized condition of the hot stamping process. Al-9Mg alloy showed uncommon deformation behavior at the 373 K and 473 K temperature conditions. The calculated curves from the constitutive equation well-matched with the measured curves from the experiments particularly under the low temperature and high strain rate conditions.
Źródło:
Archives of Metallurgy and Materials; 2021, 66, 4; 1013-1018
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microstructure and Mechanical Properties of Hot-deformed AlMg4 Alloys with the Variations of Mn, Fe, and Si Contents
Autorzy:
Lee, Da B.
Kim, Bong H.
Choi, Kweon H.
Yang, Seung Y.
Kim, Nam S.
Ha, Seong H.
Yoon, Young O.
Lim, Hyun K.
Kim, Shae
Hyun, Soong K..
Powiązania:
https://bibliotekanauki.pl/articles/351603.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
Al-Mg alloy
intermetallic compounds
homogenization
hot-rolling
microstructure
Opis:
This paper aims to investigate the microstructural evolution and mechanical properties of hot-deformed AlMg4 alloys with Mn, Fe, and Si as the main impurities. For this purpose, solidification behavior and microstructural evolution during hot-rolling and heat-treatment processes are investigated by using theoretical calculations and experimental characterization. The crystallization and morphological transformation of intermetallic Al3 Fe, Al6 Mn, and Mg2 Si phases are revealed and discussed in terms of the variation in chemical composition. Following a homogenization heat-treatment, the effect of heat treatment on the intermetallic compounds is also investigated after hot-rolling. It was revealed that the Mg2 Si phase can be broken into small particles and spherodized more easily than the Al3 Fe intermetallic phase during the hot-rolling process. For the Mn containing alloys, both yield and ultimate tensile strength of the hot-rolled alloys increased from 270 to 296 MPa while elongation decreased from 17 to 13%, which can be attributed to Mn-containing intermetallic as well as dispersoid.
Źródło:
Archives of Metallurgy and Materials; 2020, 65, 4; 1255-1259
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
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