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Wyszukujesz frazę "81.70.Pg" wg kryterium: Temat


Wyświetlanie 1-5 z 5
Tytuł:
Phase Transformation and Sintering of Algeria Clay Powder
Autorzy:
Beddiar, L.
Sahnoune, F.
Heraiz, M.
Redaoui, D.
Powiązania:
https://bibliotekanauki.pl/articles/1033574.pdf
Data publikacji:
2017-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.05.Mh
81.70.Pg
81.30.Mh
Opis:
Clay is one of the most used natural materials in the ceramic industry with various applications such as pottery, tiles, cement and bricks. The latter are used as a building material because of their excellent thermal and mechanical properties. In the present study, Algerian clay from Al-maathed area, M'sila district, was used to prepare bricks. The chemical composition of the clay was determined using X-ray fluorescence. Firing of clay was carried out in the temperature range 20-1000°C, at different heating rates. The present phases and their transformations, the activation energy, and the sintering mechanism were evaluated using X-ray diffraction, differential thermal analysis, thermogravimetric analysis and dilatometry. The activation energy for the sintering mechanism obtained from non-isothermal treatments is 420 kJ/mol. The value of the Avrami exponent, n, is determined from the shape of the crystallization exothermic dependence. It is related to m parameter (a numerical factor which depends on the dimensionality of crystal growth) obtained by Matusita method. Both of which are about 1.2 for clay sintering. These values indicate that bulk nucleation is dominant in clay sintering by three-dimensional growth, with polyhedron-like morphology controlled by interface reaction.
Źródło:
Acta Physica Polonica A; 2017, 131, 3; 566-568
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The Kinetics of Spinel Formation of Algerian Halloysite by Differential Thermal Analysis
Autorzy:
Heraiz, M.
Sahnoune, F.
Belhouchet, H.
Raghdi, A.
Ouali, A.
Powiązania:
https://bibliotekanauki.pl/articles/1033398.pdf
Data publikacji:
2017-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.70.Pg
81.20.Ev
82.20.-w
Opis:
The kinetics of spinel (Al-Si) crystallization from Algerian halloysite (DD1) was investigated using differential thermal analysis. Experiments were carried out on samples between room temperature and 1400°C with constant heating rate from 2 to 20°C min¯¹. The activation energies measured from isothermal and non-isothermal treatments were 1054.85 and 1140 kJ mol¯¹, respectively, for the spinel (Al-Si) formation. The Avrami constant n obtained by the Ligero method and the m parameter obtained by the Matusita method were about 2 for spinel crystallization. This value indicates that the crystallization mechanism of Al-Si spinel phase proceeds by bulk nucleation of the phase formation with a constant number of nuclei and that the three-dimensional growth of crystals is controlled by diffusion.
Źródło:
Acta Physica Polonica A; 2017, 131, 1; 139-142
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal Decomposition Kinetics of Algerian Tamazarte Kaolin by Differential Thermal Analysis (DTA)
Autorzy:
Sahnoune, F.
Heraiz, M.
Belhouchet, H.
Saheb, N.
Redaoui, D.
Powiązania:
https://bibliotekanauki.pl/articles/1033455.pdf
Data publikacji:
2017-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
82.30.Lp
81.05.Je
81.05.Mh
81.70.Pg
Opis:
In the present study, the kinetics of meta-kaolinite (Al₂O₃·2SiO₂) formation from Algerian Tamazarte kaolin was investigated by using differential thermal analysis. The differential thermal analysis and the thermogravimetric experiments were carried out on samples between room temperature and 1400°C, at heating rates from 10 to 40°C min¯¹. X-ray diffraction was used to identify the phases present in the samples. The activation energies measured by differential thermal analysis from isothermal and non-isothermal treatments using Johnson-Mehl-Avrami methods with Ligero approximation and using Kissinger-Akahira-Sunose methods were around 145 and 159 kJ/mol, respectively. The Avrami parameter n which indicates the growth morphology parameters were found to be almost equal to 1.60, using non-isothermal treatments, and equal to 1.47 using isothermal treatments. The numerical factor which depends on the dimensionality of crystal growth was 1.60 obtained using Matusita et al. equation. The frequency factor calculated using the isothermal treatment is equal to 1.173× 10⁷ s¯¹. Analysis of the results have shown that bulk nucleation was dominant during kaolinite transformation, followed by three-dimensional growth of meta-kaolinite with polyhedron-like morphology, controlled by diffusion from a constant number of nuclei.
Źródło:
Acta Physica Polonica A; 2017, 131, 3; 382-385
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanism and kinetic parameters of the thermal decomposition of gibbsite Al(OH)₃ by thermogravimetric analysis
Autorzy:
Redaoui, D.
Sahnoune, F.
Heraiz, M.
Raghdi, A.
Powiązania:
https://bibliotekanauki.pl/articles/1057886.pdf
Data publikacji:
2017-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.70.Pg
81.05.Je
81.05.Mh
81.30.Mh
07.85.Nc
Opis:
In this study, the mechanism and the kinetic parameters of the thermal decomposition of gibbsite Al(OH)₃ were studied by differential thermogravimetry technique under non-isothermal conditions, between room temperature and 1200 K at heating rates of 5, 10, 15 and 20°C min¯¹. The obtained differential thermogravimetry curves show clearly three distinct peaks. The first peak is due to the partial dehydroxylation of gibbsite. Among the 32 types of differential equations of non-isothermal kinetics, we have found that the most suitable mechanism is (A_{3/2}: g(x)=[-ln(1-x)]^{2/3}) also called Avrami-Erofeev equation of order 2/3. The values of the activation energy E_{A} and of the pre-exponential factor K are 157 kJ mol¯¹ and 7.58×10¹⁵ s¯¹, respectively. The second peak corresponds to the decomposition of gibbsite to boehmite. Decomposition is controlled by the rate of second-order reaction (F₂: g(x)=(1-x)¯¹-1), under the applied conditions. The activation energy E_{A} and pre-exponential factor K correspond to 243 kJ mol¯¹ and 3.73×10²² s¯¹, respectively. The third peak is due to transformation of boehmite to alumina. However the mechanism for such transformation is better described by the 3/2 rate order reaction (F_{3/2}: g(x)=(1-x)^{-1/2}-1). In addition, the values of E_{A} and K were determined to be around 296 kJ mol¯¹ and 1.82×10¹⁹ s¯¹, respectively. The results of differential thermogravimetry were supplemented by the differential thermal analysis. X-ray powder diffraction analysis was carried out for samples of gibbsite treated at different temperatures between 200 and 1200°C in 200°C steps.
Źródło:
Acta Physica Polonica A; 2017, 131, 3; 562-565
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
    Wyświetlanie 1-5 z 5

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