Hydrogen desorption kinetics of melt-spun and hydrogenated Mg90Ni10 and Mg80Ni10Y10 using in situ synchrotron, X-ray diffraction and thermogravimetry

2010 ◽  
Vol 496 (1-2) ◽  
pp. 608-613 ◽  
Author(s):  
Siarhei Kalinichenka ◽  
Lars Röntzsch ◽  
Carsten Baehtz ◽  
Bernd Kieback
2011 ◽  
Vol 509 ◽  
pp. S629-S632 ◽  
Author(s):  
Siarhei Kalinichenka ◽  
Lars Röntzsch ◽  
Carsten Baehtz ◽  
Thomas Weißgärber ◽  
Bernd Kieback

2014 ◽  
Vol 32 (3) ◽  
pp. 385-390
Author(s):  
Aysel Kantürk Figen ◽  
Bilge Coşkuner ◽  
Sabriye Pişkin

AbstractIn the present study, hydrogen desorption properties of magnesium hydride (MgH2) synthesized from modified waste magnesium chips (WMC) were investigated. MgH2 was synthesized by hydrogenation of modified waste magnesium at 320 °C for 90 min under a pressure of 6 × 106 Pa. The modified waste magnesium was prepared by mixing waste magnesium with tetrahydrofuran (THF) and NaCl additions, applying mechanical milling. Next, it was investigated by X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET) techniques in order to characterize its structural properties. Hydrogen desorption properties were determined by differential scanning calorimetry (DSC) under nitrogen atmosphere at different heating rates (5, 10, and 15 °C/min). Doyle and Kissenger non-isothermal kinetic models were applied to calculate energy (Ea) values, which were found equal to 254.68 kJ/mol and 255.88 kJ/mol, respectively.


2020 ◽  
Vol 53 (4) ◽  
pp. 1163-1166
Author(s):  
Karsten Mesecke ◽  
Winfried Malorny ◽  
Laurence N. Warr

This note describes an autoclave chamber developed and constructed by Anton Paar and its application for in situ experiments under hydrothermal conditions. Reactions of crystalline phases can be studied by successive in situ measurements on a conventional laboratory X-ray diffractometer with Bragg–Brentano geometry at temperatures <483 K and saturated vapour pressure <2 MPa. Variations in the intensity of X-ray diffraction reflections of both reactants and products provide quantitative information for studying the reaction kinetics of both dissolution and crystal growth. Feasibility is demonstrated by studying a cementitious mixture used for autoclaved aerated concrete production. During a period of 5.7 h at 466 K and 1.35 MPa, the crystallization of torbermorite and the partial consumption of quartz were monitored.


2016 ◽  
Vol 88 (11) ◽  
pp. 1684-1692 ◽  
Author(s):  
Lukas C. Buelens ◽  
Vladimir V. Galvita ◽  
Hilde Poelman ◽  
Christophe Detavernier ◽  
Guy B. Marin

2014 ◽  
Vol 1645 ◽  
Author(s):  
Romain VAUCHY ◽  
Renaud.C. BELIN ◽  
Anne-Charlotte ROBISSON ◽  
Fiqiri HODAJ

ABSTRACTUranium-plutonium mixed oxides incorporating high amounts of plutonium are considered for future nuclear reactors. For plutonium content higher than 20%, a phase separation occurs, depending on the temperature and on the oxygen stoichiometry. This phase separation phenomenon is still not precisely described, especially at high plutonium content. Here, using an original in situ fast X-ray diffraction device dedicated to radioactive materials, we evidenced a phase separation occurring during rapid cooling from 1773 K to room temperature at the rate of 0.05 and 2 K per second for a (U0.55Pu0.45)O2-x compound under a reducing atmosphere. The results show that the cooling rate does not impact the lattice parameters of the obtained phases at room temperature but their fraction. In addition to their obvious fundamental interest, these results are of utmost importance in the prospect of using uranium-plutonium mixed oxides with high plutonium content as nuclear fuels.


2000 ◽  
Vol 104 (11) ◽  
pp. 2467-2476 ◽  
Author(s):  
H. Natter ◽  
M. Schmelzer ◽  
M.-S Löffler ◽  
C. E. Krill ◽  
A. Fitch ◽  
...  

2011 ◽  
Vol 172-174 ◽  
pp. 646-651 ◽  
Author(s):  
Gamra Tellouche ◽  
Khalid Hoummada ◽  
Dominique Mangelinck ◽  
Ivan Blum

The phase formation sequence of Ni silicide for different thicknesses is studied by in situ X ray diffraction and differential scanning calorimetry measurements. The formation of a transient phase is observed during the formation of δ-Ni2Si; transient phases grow and disappear during the growth of another phase. A possible mechanism is proposed for the transient phase formation and consumption. It is applied to the growth and consumption of θ-Ni2Si. A good accordance is found between the proposed model and in situ measurement of the kinetics of phase formation obtained by x-ray diffraction and differential scanning calorimetry for higher thickness.


2020 ◽  
Author(s):  
Li Yi ◽  
Ruixin Zhang ◽  
Siyu Yang

&lt;p&gt;&amp;#160; &amp;#160; Subduction zone is a distinct activity structure of hypocenter distribution of earthquakes. Hydrous minerals are involved in the chemical and physical activities in subduction zones. As a widely distributed hydrous mineral in shallow depths, talc has potential significance in various fault activities, and its dehydration reaction may be an important cause of the earthquake. Iron is a main element of the earth's crust, and the iron contents of hydrous minerals have a large impact on melting point, the rheological strength physical and chemical properties of the rocks. As a common hydrous mineral, the iron content of talc is not uniform; therefore, it is very important to study the dehydration kinetics of talc with different iron content.&lt;/p&gt;&lt;p&gt;&amp;#160; &amp;#160; The dehydration reaction of three different iron contents talc was studied by means of synchronous thermal analysis, high temperature and high pressure differential thermal experiment and in-situ synchrotron X-ray diffraction experiment. Data of synchronous thermal analysis was calculated by Flynn-Wall-Ozawa (FWO). The activation energies of different iron content talc were calculated as 359.8 kJ/mol&amp;#65288;FeO&amp;#65306;0.4wt%&amp;#65289;&amp;#65292;368.2.0 kJ/mol&amp;#65288;FeO&amp;#65306;2.0wt&amp;#65285;&amp;#65289;&amp;#65292;belonging to the second-order reaction. Data of in-situ synchrotron X-ray diffraction experiment was fitted by Avrami equation, E=350 kJ/mol&amp;#65288;FeO&amp;#65306;2.0wt&amp;#65285;&amp;#65289;&amp;#65292;n=1.67. The dehydration of talc followed random nucleation and growth mechanism. High content of iron obviously resulted in lower dehydration temperature.&lt;/p&gt;&lt;p&gt;&amp;#160; The release rate of talc dehydration fluid was 2.3E-05 to 6.1E-06 obtained by in-situ synchrotron X-ray diffraction experiment&amp;#65292;it could lead to local overpressure induced rock brittle fracture. The supercritical fluid produced by the dehydration of talc in the subduction zone further attenuates the rock, resulting in local overpressure, which eventually leads to rock failure. The results suggested that the dehydration of different iron contents of talc may occur at the different depth around hundreds of kilometers, so the study was significant to our understanding of the genetic mechanism of earthquakes in the subduction zone.&lt;/p&gt;


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