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Wyszukujesz frazę "81.20.ev" wg kryterium: Temat


Tytuł:
Nanostructure features, phase relationships and thermoelectric properties of melt-spun and spark-plasma-sintered skutterudites
Autorzy:
Kogut, Iu.
Nichkalo, S.
Ohorodniichuk, V.
Dauscher, A.
Candolfi, C.
Masschelein, P.
Jacquot, A.
Lenoir, B.
Powiązania:
https://bibliotekanauki.pl/articles/1052685.pdf
Data publikacji:
2018-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.15.Eb
72.15.Jf
72.20.Pa
66.70.Df
81.20.Ev
81.16.-c
81.40.Gh
Opis:
Reduction of thermal conductivity remains a main approach relevant to enhancement of figure-of-merit of most thermoelectric materials. Melt spinning combined with spark plasma sintering appears to be a vital route towards fine-grain skutterudites with improved thermoelectric performance. However, upon high-temperature processing the Fe_{4-x}Co_{x}Sb_{12}-based skutterudites are prone to decompose into multiple phases, which deteriorate their thermoelectric performance. In this study we addressed the effects of combined melt spinning and spark plasma sintering on the phase composition and microstructural properties of filled Fe_{4-x}Co_{x}Sb_{12} as well as their influence on thermoelectric characteristics of these compounds. The crystallites of filled Fe_{4-x}Co_{x}Sb_{12} were effectively reduced to sizes below 100 nm upon melt spinning, but also severe decomposition with weakly preserved nominal phase was observed. Spark plasma sintering of melt spun skutterudites resulted in even further reduction of crystallites. Upon short annealing and sintering the n-type materials easily restored into single-phase filled CoSb₃ with nanoscale features preserved, while secondary phases of FeSb₂ and Sb remained in p-type compounds. Relatively high figure-of-merit ZT_{max} of 0.9 at T ≈ 400°C has been gained in nanostructured Yb_{x}Co₄Sb_{12}, however, no significant reduction of thermal conductivity was observed. Abundant impurities in p-type filled Fe_{4-x}Co_{x}Sb_{12} led to drastic drop in their ZT, which even further degraded upon thermal cycling.
Źródło:
Acta Physica Polonica A; 2018, 133, 4; 879-883
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of Nanocrystalline Cu25Mo Electrical Contact Material Synthesized via Ball Milling
Autorzy:
Biyik, S.
Powiązania:
https://bibliotekanauki.pl/articles/1031886.pdf
Data publikacji:
2017-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
84.32.Dd
Opis:
In this study, Cu-based Mo-doped composite powder was synthesized by ball milling technique. Elemental powder mixture containing 25 wt.% Mo was milled in a high-energy planetary-type ball mill to achieve homogeneously mixed composite powder. Characterization of the starting and the milled powders was carried out using scanning electron microscopy and laser diffraction analysis. It was found that particle size of powder had gradually decreased with increasing milling duration. scanning electron microscope pictures, corresponding to the later stages of milling process prove that nanocrystalline powders were obtained after milling duration of 30 h. Prolonged milling durations lead to powder contamination, which is undesirable for contact applications, where the purity is of big importance. Therefore, optimum milling duration was determined to be 30 h.
Źródło:
Acta Physica Polonica A; 2017, 132, 3; 886-888
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of CaO Addition on the Sintering Behaviour of Anorthite Formed from Kaolin and CaO
Autorzy:
Ouali, A.
Sahnoune, F.
Belhouchet, H.
Heraiz, M.
Powiązania:
https://bibliotekanauki.pl/articles/1032557.pdf
Data publikacji:
2017-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Je
81.05.Mh
81.20.Ev
81.70.Pg
65.40.De
65.60.+a
Opis:
Thermal reactions and sintering behavior of kaolin DD3 (Djebel Debbagh, Algeria) and CaO mixtures to obtain dense anorthite ceramics were investigated. Mixed powders were uniaxially pressed and fired between 850 and 1150°C. Firing the pressed specimens yielded a dense anorthite ceramics. The sintered density increased with increase of CaO content and reached the maximum value of 2.57 g/cm³ for the composition containing 10 wt% CaO and fired at 1150°C. Their coefficient of linear expansion of the sintered samples at 1100°C decreases with the addition of CaO. X-ray diffraction experiments carried out on the samples containing varied amount of CaO and fired at the temperatures higher than 1000°C for 2 h showed the presence of only anorthite phase.
Źródło:
Acta Physica Polonica A; 2017, 131, 1; 159-161
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Sintering Time on Hardness and Wear Behaviours of Carbon Nanotubes Reinforced Aluminium Matrix Composites
Autorzy:
Yildirim, M.
Ozyurek, D.
Guru, M.
Powiązania:
https://bibliotekanauki.pl/articles/1033387.pdf
Data publikacji:
2017-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
Opis:
In this study, the effects of sintering time on hardness and wear behaviour were investigated of carbon nanotubes reinforced aluminium matrix composites. 1% multi wall carbon nanotubes (90% purity with 9.5 nm in diameter, 1.5 μm in length) and gas atomized 7075 Al alloy powders were mechanical milled for 120 min in a planetary ball mill. Mechanical milled aluminium composite powders were cold pressed under 520 MPa. Pre-shaped samples were sintered in atmosphere controlled furnace at 580°C for three different sintering times (1, 2, and 3 h). As a result of study, it was observed that the hardness values of composites were decreased with increasing sintering time and the weight loss was decreased. It was determined from worn surface SEM images that adhesive wear mechanisms were dominant.
Źródło:
Acta Physica Polonica A; 2017, 131, 1; 92-95
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Enhanced Mechanical Performance of Aluminum Glass Fiber Reinforced Foam Material by Cu Modification
Autorzy:
Ertürk, A.
Aydin, I.
Powiązania:
https://bibliotekanauki.pl/articles/1033530.pdf
Data publikacji:
2017-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Bx
81.05.Rm
81.20.Ev
81.70.Bt
Opis:
Glass fiber-reinforced aluminum foam and its modified forms, using 1 and 3 wt.% of Cu, were produced by powder sintering process, using spherical carbamide particles as space holders. The foams with 40 and 60 vol.% porosity fractions were successfully produced after water leaching and sintering procedures. Compression test was performed on foam samples to compare both, the compressive properties and energy absorption behavior of them. The composite foam samples with Cu modification have shown a higher compressive strength than the parent material foam. The average plateau stress and energy absorption capacity of foams produced in this study, achieved via utilizing 3 wt.% Cu, were 7.06 MPa and 3.51 MJ/m³, respectively.
Źródło:
Acta Physica Polonica A; 2017, 131, 3; 470-473
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication and Arc-Erosion Behavior of Ag8SnO₂ Electrical Contact Materials under Inductive Loads
Autorzy:
Biyik, S.
Aydin, M.
Powiązania:
https://bibliotekanauki.pl/articles/1030286.pdf
Data publikacji:
2017-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
81.70.-q
07.50.-e
84.32.Dd
Opis:
In this study, Ag-based SnO₂-reinforced electrical contact materials were produced by powder metallurgy and mechanical alloying techniques. Elemental powder mixture containing 8 wt.% SnO₂ was milled in a high-energy planetary-type ball mill, to achieve homogeneously mixed composite powder, and subsequently pressed in a closed die to obtain green compacts with a cylindrical shape and then sintered under vacuum to obtain composites. Composites were then subjected to electrical wear tests under inductive loads to investigate the arc-erosion performance of electrical contacts. Surface deterioration and mass losses of electrical contacts were also evaluated, as a function of increasing switching number. Characterization of the starting and composite powders, green compacts, composites and arc-originated surface deterioration was carried out using scanning electron microscopy and energy-dispersive X-ray spectroscopy. It was found that powder particle size had decreased with the increasing milling time. Density and hardness values of the composites had increased, whereas porosity had decreased with the increasing sintering temperature. Optimum sintering temperature was determined as 900°C. The arc-affected zones became bigger with the increase of the number of switching operations. Furthermore, comparison between surface morphologies and mass losses of arc-eroded specimens had revealed that the stationary contacts exhibit higher rates of erosion than the movable contacts.
Źródło:
Acta Physica Polonica A; 2017, 131, 3; 339-342
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fabrication of Transparent Yttria Ceramics by Spark Plasma Sintering
Autorzy:
Korkmaz, E.
Sahin, F.
Powiązania:
https://bibliotekanauki.pl/articles/1032083.pdf
Data publikacji:
2017-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Je
81.20.Ev
81.40.Tv
42.70.Hj
Opis:
Rapid densification of yttria (Y₂O₃) ceramics without sintering aids via spark plasma sintering at relatively low temperature of 1300°C for 40 minutes at two-step pressure profile, followed by post-annealing at 1050°C for 6 hours in air was attempted. Effect of preload pressure on microstructure, Vickers hardness, fracture toughness and optical in-line transmittance was investigated. Densification during spark plasma sintering did not involve any phase transformation and all phases have shown cubic structure according to X-ray analysis. The highest hardness and fracture toughness value was recorded to be 7.60±0.18 GPa and 1.16±0.07 MPa m^{1/2} with 10 MPa preload and 100 MPa final load. In addition to this, the highest transmittance with a value of 76.7% at a wavelength of 2000 nm was obtained when studied with 10 MPa preload and 100 MPa final load.
Źródło:
Acta Physica Polonica A; 2017, 131, 3; 460-462
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Energy Ball Milling of YAG Powders: Sintering Properties and Microstructural Evaluation
Autorzy:
Ozer, A.
Kilic, O.
Powiązania:
https://bibliotekanauki.pl/articles/1030279.pdf
Data publikacji:
2017-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
Opis:
Outstanding properties of sintered ceramics due to lower sintering temperatures and smaller grain sizes are of much attention to many researchers. In this study, YAG phase was formed successfully with mechanical activation of powder mixtures by high energy ball milling of powders at different speeds. The powders were compacted and sintered at three different temperatures to evaluate the sintering density, phase formation and grain formation. It was found that increasing activation time, which agitates the powder mixing more accurately, has led to an increase in the relative density, as compared to non-activated samples, sintered at same temperatures. Up to 95% ot the theoretical density were reached, indicating the partial liquid phase formation of Y-A related phases. YAG phase formation and crystallite size were evaluated using XRD and Debye-Scherrer formula. The studies of grain size and surface morphology were conducted using SEM. Since the mechanical activation of ceramic powders occurs by fragmentation and crack propagation, by brittle fracture of powders, the main mechanism of reduction of sintering temperature can be concluded to be the decreasing grain size, as well as the increasing strain on fine powder grains.
Źródło:
Acta Physica Polonica A; 2017, 131, 3; 329-331
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Imaging of Magnetic Domain Structure in $FeSi/Mn_{0.8}Zn_{0.2}Fe_2O_4$ Composite using Magnetic Force Microscopy
Autorzy:
Streckova, M.
Batko, I.
Batkova, M.
Bures, R.
Faberova, M.
Dzunda, R.
Hadraba, H.
Kubena, I.
Powiązania:
https://bibliotekanauki.pl/articles/1398262.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
72.80.Tm
75.50.Bb
75.60.-d
81.20.-n
81.20.Ev
81.20.Fw
Opis:
Soft magnetic composite was prepared by coating the commercial FeSi powder by $Mn_{0.8}Zn_{0.2}Fe_2O_4$ (MnZn) ferrite, which serves as a potential dielectric phase. MnZn ferrite was prepared by the sol-gel method followed by the auto-self combustion process. The spinel structure of MnZn ferrite was analyzed by X-ray diffraction technique. The composite material was prepared by uniaxial compaction technique and sintered either by conventional or unconventional microwave method. The microwave sintering was applied in order to reduce a grain growth and decrease the overall sintering time. The microstructure of FeSi powder is formed by grains of different diameter. Magnetic force microscopy and scanning electron microscopy were used for an investigation of the correlation between the grain size, grain boundaries and magnetic domains. Magnetic force microscopy visualization of magnetic domains in the prepared soft magnetic composite brings insight into how the magnetically active coating (MnZn ferrite) influences the soft magnetic (FeSi) powder under the influence of the external magnetic field.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 714-716
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of spark plasma sintering on microstructure and properties of bulk LaCaSrMnO magnetocaloric materials
Autorzy:
Zmorayová, K.
Antal, V.
Kováč, J.
Diko, P.
Noudem, J.
Powiązania:
https://bibliotekanauki.pl/articles/1053176.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.47.Lx
61.72.-y
75.30.Kz
77.80.B-
81.70.Pg
81.20.Ev
81.30.Fb
Opis:
Polycrystalline La_{0.67}Ca_{0.33-x}Sr_xMnO₃ (x=0.33, 0.03, 0) (LCSM) perovskite samples treated by spark plasma sintering technique were investigated. This study proved influence of the sintering temperature on microstructure of these perovskite ceramics. The thermogravimetric measurements revealed the possibility of increase of oxygen content in studied LCSM samples by additional annealing under oxygen atmosphere and low temperature. Finally, the effect of this annealing on magnetic properties was demonstrated.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 804-806
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Investigation of Mechanical Properties of Fe-Based Metal Matrix Composites by Warm Compaction for Gear Production
Autorzy:
Gun, T.
Simsir, M.
Powiązania:
https://bibliotekanauki.pl/articles/1032024.pdf
Data publikacji:
2017-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.ev
87.15.La
87.64.M
Opis:
In this study, mechanical behavior of iron-based (Fe-0.8C-2.0Cu-4.5Ni-1.8Mo-1.0B (wt.%)) metal matrix composite synthesized by powder metallurgy was investigated for gear production. Metal matrix composite has been produced by warm compaction, followed by free sintering in controlled Ar gas atmosphere. Green composite was produced under pressure of 650 MPa at 160°C. The green products have been sintered at various temperatures (1050, 1150 and 1250°C) and for various time periods (30, 60 and 90 min). Mechanical tests (hardness and wear tests) have been conducted. The microstructure and the worn surfaces of the samples have been examined under scanning electron microscope and analyzed by energy dispersive spectroscopy and X-ray diffraction method. The results have shown that hardness and wear resistance of the samples increase with increasing sintering temperature and time. Effect of sintering temperature is greater than that of sintering time. The highest hardness and wear resistance have been obtained in the composite sample produced at 1250°C for 90 min.
Źródło:
Acta Physica Polonica A; 2017, 131, 3; 443-447
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical Properties of Soft Magnetic Composites at the Temperature of Liquid Nitrogen
Autorzy:
Przybylski, M.
Kapelski, D.
Ślusarek, B.
Powiązania:
https://bibliotekanauki.pl/articles/1030233.pdf
Data publikacji:
2017-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Cc
81.05.Zx
81.20.Ev
81.70.Bt
Opis:
Soft magnetic composites are used in a wide range of applications working in different environmental conditions, between others, in different temperatures. Nowadays, devices often work in cryogenic temperatures. The paper shows influence of liquid nitrogen temperature on mechanical properties of soft magnetic composites prepared from ABC100.30 powder bonded by epoxy resin. Mechanical properties of samples were measured in room and liquid nitrogen temperatures. Compressive strength and transverse rapture strength increase with decreasing temperature. This type of soft magnetic composite can be applied in magnetic circuits of devices working in cryogenic temperatures. The results of measurement show that new devices, especially electric machines, working in these temperatures can be designed with higher mechanical loadings than devices working at room temperature.
Źródło:
Acta Physica Polonica A; 2017, 131, 5; 1199-1203
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanochemical Preparation and Magnetic Properties of Fe₃O₄/ZnS Nanocomposite
Autorzy:
Bujňáková, Z.
Zorkovská, A.
Kováč, J.
Powiązania:
https://bibliotekanauki.pl/articles/1032141.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Bc
81.20.Ev
81.20.Wk
Opis:
Powder nanocomposite of Fe₃O₄/ZnS was prepared by mechanochemical synthesis in a planetary ball mill. In this reaction natural magnetite mineral Fe₃O₄ was used, together with zinc acetate (CH₃COO)₂Zn·2H₂O and sodium sulfide Na₂S·9H₂O, as precursors for the zinc sulfide ZnS. X-ray diffraction revealed that the sample is composed of small nanocrystalline particles, containing Fe₃O₄ and ZnS. The non-milled magnetite showed distinctive Verwey transition at around 120 K, this becomes suppressed after milling, as a consequence of structural disorder and presence of defects. Moreover, the reduction of saturation magnetization from 91 A m²/kg to 69.2 A m²/kg was observed, as a consequence of the milling process. The magnetization of the Fe₃O₄/ZnS nanocomposite was the lowest (34.5 A m²/kg), due to the milling and to the decreased weight fraction of the ferrimagnetic component. Nevertheless, the Fe₃O₄/ZnS sample demonstrates ferrimagnetic behavior as well, and its structure is less perturbed by milling, the Verwey transition, although less impressive, but is preserved.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 1120-1122
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Microdeformation Processes in Soft Magnetic Compounds
Autorzy:
Bidulský, R.
Bidulská, J.
Petroušek, P.
Fedoriková, A.
Dudrová, E.
Actis Grande, M.
Powiązania:
https://bibliotekanauki.pl/articles/1032942.pdf
Data publikacji:
2017-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.-y
81.20.Ev
81.40.Np
Opis:
Porosity can be defined in different ways. The most frequently used definition is the total porosity, which is the total volume fraction of empty space in the specimen. The presence of pores strongly affects the fracture mode. Besides the evaluation of geometry and quality of connections, fractographic analysis enables a quantification of the important microstructural characteristics of the plane porosity. This quantity allows to quantify the existing relations between microstructure and properties. The fractographic evaluation of the distribution of microdeformation processes in the volume of experimental material demonstrates the influence of porosity on the concentration of deformation flows into the microvolume of connections. Plain porosity contributes to the recognition of critical microstructural defects and therefore, to enable evaluating the relationship between the processing parameters, microstructural constituents, and pores. In the fractography evaluation, the analysis of the quality of interparticle bonding using determination of elementary types of fracture facets allows to interpret the mechanical and plastic properties of investigated materials.
Źródło:
Acta Physica Polonica A; 2017, 131, 5; 1367-1370
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Optimization of Mechanical Alloying Parameters of Cu25W Electrical Contact Material
Autorzy:
Biyik, S.
Aydin, M.
Powiązania:
https://bibliotekanauki.pl/articles/1031274.pdf
Data publikacji:
2017-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
84.32.Dd
Opis:
In this study, the effect of mechanical alloying parameters, namely the effect of process control agent, ball-to-powder weight ratio and milling duration, on the synthesis of Cu25W composite powder was investigated. Planetary-type ball milling equipment was used to conduct mechanical alloying experiments. Stearic acid was used as the process control agent in order to establish a balance between cold welding and fracturing. The optimum amount of stearic acid was determined as a function of particle size and milling time at constant speed. By using this optimum amount of process control agent, three different ball-to-powder weight ratio values were also employed, and the effect of ball-to-powder weight ratio on particle size and morphology of Cu25W composite powders was investigated. The microstructural evolution of the milled powders was characterized using scanning electron microscopy and laser diffraction analysis. The test results have shown that the morphology and particle size distribution of the milled powders change significantly depending upon the milling parameters. In addition, higher ball-to-powder weight ratio values tend to lower the milling duration for the same amount of particle size reduction. However, particle size reduction suffers beyond the maximal value of ball-to-powder weight ratio, especially in the later stages of mechanical alloying.
Źródło:
Acta Physica Polonica A; 2017, 132, 3; 909-912
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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