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Wyświetlanie 1-10 z 125
Tytuł:
Fabrication, Structure and Consolidation of NiAl-Al$\text{}_{2}$O$\text{}_{3}$ Mechanically Alloyed Nanocomposite Powders
Autorzy:
Oleszak, D.
Michalski, A.
Majewski, T.
Powiązania:
https://bibliotekanauki.pl/articles/2035470.pdf
Data publikacji:
2002-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
Opis:
Reactive milling of NiO + Al powder mixture resulted in the formation of NiAl-Al$\text{}_{2}$O$\text{}_{3}$ nanocomposite powders, with a crystallite size of about 20 nm. The Hall-Williamson analysis revealed that NiAl showed an orientation dependent crystallite size after short processing time and orientation dependent internal strain after long milling time. Both anisotropies were removed by heating the powders in the differential scanning calorimetry. Calorimetric studies showed one exothermic effect attributed to the reduction reaction of NiO and endothermic one associated with melting of Al. Two methods were applied for powders compaction: resistance sintering and pulse electric discharge. In both cases the densities of about 90% of the theoretical value were achieved. A significant increase in average NiAl crystallites size in compacted samples was observed, up to several hundreds of nanometers.
Źródło:
Acta Physica Polonica A; 2002, 102, 2; 187-192
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:
Fabrication and Characterisation of Bronze Pads and Comparison with Commercial Bronze Pads
Autorzy:
Demir, A.
Powiązania:
https://bibliotekanauki.pl/articles/1185359.pdf
Data publikacji:
2016-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
Opis:
CuSn10 pre-alloyed bronze with iron and graphite powders were mixed, pressed and sintered for the bronze pad fabrication. The powder mix was pressed under pressure in the range of 100-600 MPa and sintered at temperatures between 780-850°C. The optimum compression was at 500 MPa and the optimal sintering temperatures was 730°C. 2 wt.% of graphite addition was sufficient to adjust the friction and wear properties of produced bronze pad samples. Optical microscope and SEM images showed that a homogenous powder mix was achieved. The produced bronze samples and the commercial ones were compared and beneficial properties of them were determined. The wear behaviours of both the produced friction materials and the commercial pads were examined. The coefficient of friction and wear rates were determined. The sintered bronze samples and the commercial bronze pads have exhibited similar wear behaviour, although the commercial one have contained ceramic particles.
Źródło:
Acta Physica Polonica A; 2016, 129, 4; 880-882
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:
The Effect of Milling Speed on Particle Size and Morphology of Cu25W Composite Powder
Autorzy:
Biyik, S.
Aydin, M.
Powiązania:
https://bibliotekanauki.pl/articles/1194030.pdf
Data publikacji:
2015-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
Opis:
In this study, the effect of milling speed on particle size and morphology of Cu25W composite powder produced by high-energy ball milling was investigated. For this aim, commercial elemental copper and tungsten powders were milled in a planetary-type ball mill for different milling durations. Ball-to-powder weight ratio was selected as 10:1. Three different milling speeds, namely 200, 300, and 400 rpm were used throughout the tests. In order to avoid agglomeration and to decrease the tendency of cold welding among powder particles, stearic acid in amount of 2 wt.% was used as a process control agent. The morphological and microstructural evolution of the milled powders was evaluated by scanning electron microscopy. In addition, the variation of particle size and powder morphology as a function of milling duration was determined. As a result of this effort, the milling duration was found to have strong effect on the structural evolution of the powder, and the optimum particle size as a function of milling speed was determined.
Źródło:
Acta Physica Polonica A; 2015, 127, 4; 1255-1260
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spark Plasma Sintering of Boron Carbide Ceramics Using Metallic Silicon in Square Cross Section
Autorzy:
Cengiz, M.
Sahin, F.
Powiązania:
https://bibliotekanauki.pl/articles/1401426.pdf
Data publikacji:
2015-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
Opis:
B₄C ceramics were fabricated by spark plasma sintering (SPS) technique with 5 vol.% silicon as sintering additive. Optimization of SPS method production parameters for B₄C ceramics having geometries 50×50×5 mm, square cross section will be performed. The sintering process was carried out at different temperatures by applying 40 MPa of pressure under vacuum atmosphere. The effect of silicon additive, sintering temperature and different soaking times on density, vickers hardness, fracture toughness and microstructure were examined. The mechanical properties of the B₄C ceramics having silicon as additive were compared with the results of monolithic B₄C. The hardness and fracture toughness of the samples were evaluated by the vickers indentation technique. Microstructures of spark plasma sintered B₄C samples with different parameters in square cross section were characterized by using SEM technique.
Źródło:
Acta Physica Polonica A; 2015, 127, 4; 1370-1372
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization Investigations of W-Ni Matrix Composites Reinforced with $TiB_2$ and $La_2O_3$
Autorzy:
Gökçe, H.
Balcı, Ö.
Ağaoğulları, D.
Demirkan, Ö.
Genç, A.
Öveçoğlu, M.
Duman, İ.
Powiązania:
https://bibliotekanauki.pl/articles/1399817.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
Opis:
W-1 wt% Ni (W1Ni) matrix composites reinforced with $TiB_2$ and $La_2O_3$ particles were fabricated via mechanical alloying and activated sintering methods. Powder blends with compositions of W1Ni-2 wt% TiB_2-x wt% $La_2O_3$ (x = 0.5, 1) were mechanically alloyed for 6 and 12 h. The results showed that increase in mechanical alloying duration to 12 h causes the decline of grain sizes of the W-Ni matrix to nanoscales. $TiB_2//La_2O_3$ particles have a significant effect on the density/microhardness values and wear amounts of the sintered samples.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 309-312
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spark Plasma Sintering of Boron Carbide Ceramics Using Different Sample Geometries and Dimensions
Autorzy:
Cengiz, M.
Yavas, B.
Celik, Y.
Goller, G.
Yucel, O.
Sahin, F.
Powiązania:
https://bibliotekanauki.pl/articles/1216387.pdf
Data publikacji:
2014-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
81.05.Je
Opis:
$B_4C$ ceramics were fabricated by spark plasma sintering technique at 1700°C-1800C for 5 min under applied pressure of 50 MPa under vacuum atmosphere. Two different grades of $B_4C$ powder from H.C. Starck Company namely HP grade and HS grade were used in all related experiments. Effect of sample geometry and dimensions as well as sample thickness on sintering parameters were analyzed. Samples having 5 mm thickness and 50 mm diameter, 8 mm thickness in circular geometries and 50 × 50 square cross-section, 8 mm thickness were fabricated. Using the powder, which provided the densest sample, yttrium oxide $(Y_2O_3)$ was added, mixed and sintered. Optimization of SPS method production parameters for pure $B_4C$ samples and $B_4C$ samples with 5 wt% yttrium oxide additive were accomplished. The effect of geometry on density, Vickers hardness, fracture toughness, and microstructure were examined. The hardness and fracture toughness values of the samples were evaluated by the Vickers indentation technique.
Źródło:
Acta Physica Polonica A; 2014, 125, 2; 260-262
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Characterization of $Ni_3Al$ and $Ti_3Al$ Coatings Produced by Electric Current Activated Sintering Method
Autorzy:
Ergin, N.
Yoruk, G.
Ozdemir, O.
Powiązania:
https://bibliotekanauki.pl/articles/1399712.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
81.40.Pq
Opis:
The present study reports on $Ni_3Al$ and $Ti_3Al$-based intermetallics coated on AISI 1010 steel substrate by one-step pressure assisted electric current activated sintering method. Ni, Ti, and Al elemental powders were mixed in the stoichiometric ratio corresponding to the $Ni_3Al$ and $Ti_3Al$ intermetallics at molar proportion of 3:1. The mixed coating powders were placed onto the steel substrate in a mold, and pressed with compressive stress of 100 MPa and then, electric current: 1100-1200 A, voltage 2.9-3.4 V was applied for 15 min during coating. As-synthesized coatings seem to have good adherence with many small porosities. The phases formed in the $Ni_3Al$ coating layer were $Ni_3Al$ as a major phase beside NiO and $NiAl_2O_4$ trace phases, which were confirmed by X-ray diffraction analysis. However, TiAl and Ti trace phases besides major $Ti_3Al$ phase were detected in the $Ti_3Al$ coating. The hardness of the $Ni_3Al$, $Ti_3Al$ coatings and AISI 1010 substrate was approximately 321 ± 18, 445 ± 13 and 157 $HV_{0.5}$, respectively.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 245-247
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Investigation on TiNi Intermetallic Produced by Electric Current Activated Sintering
Autorzy:
Ergin, N.
Ozdemir, O.
Powiązania:
https://bibliotekanauki.pl/articles/1399714.pdf
Data publikacji:
2013-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.20.Ev
81.40.Pq
Opis:
In this study, TiNi intermetallic compounds were produced by electric current activated sintering in open air under an uniaxial pressure of 200 MPa at a maximum of 1200 A for 10 min using Ni powder (99.8% purity, 4-7 μm), Ti powder (99.5% purity, less than 44 μm). The elemental powders were mixed in the stoichiometric ratio corresponding to the TiNi intermetallic at molar proportion of 1:1. Scanning electron microscopy and X-ray diffraction analysis were used to characterize produced samples. X-ray diffraction studies revealed that the dominant phases are TiNi, $NiTi_2$, $Ni_3Ti$, TiO, and $Ni_2Ti_3$. Scanning electron microscopy examinations showed a dense microstructure with very low amount of porosity. The relative density of test materials measured according to Archimedes' principle was 96.8%, and the microhardness of materials was about 773.6 ± 123 $HV_{0.05}$.
Źródło:
Acta Physica Polonica A; 2013, 123, 2; 248-249
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-10 z 125

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