scholarly journals Effects of Ball Milling and TiF3 Addition on the Dehydrogenation Temperature of Ca(BH4)2 Polymorphs

Energies ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4828
Author(s):  
Isabel Llamas Jansa ◽  
Oliver Friedrichs ◽  
Maximilian Fichtner ◽  
Elisa Gil Bardají ◽  
Andreas Züttel ◽  
...  
Keyword(s):  
Ball Milling ◽  
Hydrogen Desorption ◽  
Reaction Pathways ◽  
Desorption Peak ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Before And After ◽  
Kinetics Of ◽  
Desorption Reaction

The changes introduced by both ball milling and the addition of small amounts of TiF3 in the kinetics of the hydrogen desorption of three different Ca(BH4)2 polymorphs (α, β and γ) have been systematically investigated. The samples with different polymorphic contents, before and after the addition of TiF3, were characterized by powder X-ray diffraction and vibrational spectroscopy. The hydrogen desorption reaction pathways were monitored by differential scanning calorimetry. The hydrogen desorption of Ca(BH4)2 depends strongly on the amount of coexistent α, β and γ polymorphs as well as additional ball milling and added TiF3 to the sample. The addition of TiF3 increased the hydrogen desorption rate without significant dissociation of the fluoride. The combination of an α-Ca(BH4)2 rich sample with 10 mol% of TiF3 and 8 h of milling led to up to 27 °C decrease of the hydrogen desorption peak temperature.

scholarly journals Hydrogen desorption kinetics of MgH2 synthesized from modified waste magnesium

2014 ◽  
Vol 32 (3) ◽  
pp. 385-390
Author(s):  
Aysel Kantürk Figen ◽  
Bilge Coşkuner ◽  
Sabriye Pişkin
Keyword(s):  
Hydrogen Desorption ◽  
Nitrogen Atmosphere ◽  
Desorption Kinetics ◽  
X Ray Diffraction ◽  
Heating Rates ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Xrf Scanning ◽  
Isothermal Kinetic ◽  
Kinetics Of

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.

scholarly journals Dehydrogenation/rehydrogenation mechanism in aluminum destabilized lithium borohydride

2009 ◽  
Vol 24 (8) ◽  
pp. 2720-2727 ◽  
Author(s):  
Xuebin Yu ◽  
Guanglin Xia ◽  
Zaiping Guo ◽  
Huakun Liu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Hydrogen Desorption ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Lithium Borohydride ◽  
Hydrogen Storage Properties ◽  
X Ray ◽  
Before And After ◽  
Storage Properties ◽  
Desorption Cycle

LiBH4/Al mixtures with various mol ratios were prepared by ball milling. The hydrogen storage properties of the mixtures were evaluated by differential scanning calorimetry/thermogravimetry analyses coupled with mass spectrometry measurements. The phase compositions and chemical state of elements for the LiBH4/Al mixtures before and after hydrogen desorption and absorption reactions were assessed via powder x-ray diffraction, infrared spectroscopy, and x-ray photoelectron spectroscopy. Dehydrogenation results revealed that LiBH4 could react with Al to form AlB2 and AlLi compounds with a two-step decomposition, resulting in improved dehydrogenation. The rehydrogenation experiments were investigated at 600 °C with various H2 pressure. It was found that intermediate hydride was formed firstly at a low H2 pressure of 30 atm, while LiBH4 could be reformed completely after increasing the pressure to 100 atm. Absorption/desorption cycle results showed that the dehydrogenation temperature increased and the hydrogen capacity degraded with the increase of cycle numbers.

Catalytic Effect of Ti on H-Desorption/Absorption Properties in MgH2 Prepared by Ball Milling

2014 ◽  
Vol 687-691 ◽  
pp. 4335-4338
Author(s):  
Yan Wang
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
Hydrogen Desorption ◽  
High Energy ◽  
X Ray Diffraction ◽  
Absorption Properties ◽  
X Ray ◽  
Milled Sample ◽  
Energy Ball ◽  
Kinetics Of

We report on the preparation and hydrogen desorption/absorption kinetics of nanocrystalline magnesium hydride (MgH2) added commercial Ti by high-energy ball milling. The phase and composition of the as-milled powders are characterized by X-ray diffraction (XRD). The results show that the milled sample contained MgH2phase, Ti phase and small amount of MgO phase. When the milling time is 30 h, the hydrogen desorption property of MgH2has been investigated and found that the sample releases 0.43, 0.86 and 0.90 wt% H2in 200 minutes at 280, 290 and 300oC , respectively. Moreover, the sample absorbs 0.48, 0.0.58 and 0.61 wt% H2in 15 minutes at 280, 290 and 300oC , respectively. It can be seen that the kinetics of hydrogen desorption/absorption of MgH2-Ti composite has been greatly enhanced compared to the pure MgH2.

Optimization of Structure of Soft Block for Design of Adaptive Polyurethanes

2020 ◽  
Vol 869 ◽  
pp. 273-279
Author(s):  
Marina A. Gorbunova ◽  
Denis V. Anokhin ◽  
Valentina A. Lesnichaya ◽  
Alexander A. Grishchuk ◽  
Elmira R. Badamshina
Keyword(s):  
Mutual Influence ◽  
Glycol Adipate ◽  
Mass Ratio ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Crystallization Conditions ◽  
Crystalline Domains ◽  
Kinetics Of

A synthesis of new di-and triblock polyurethane thermoplastic copolymers containing different mass ratio of two crystallizing blocks - poly (1,4-butylene glycol) adipate and poly-ε-caprolactone diols was developed. Using combination of danamometric analysis, IR-spectroscopy, differential scanning calorimetry and X-ray diffraction, the effect of the soft block composition and crystallization conditions on crystal structure and thermal behavior of the obtained polymers have been studied. For the triblock copolymers we have shown a possibility of control the kinetics of material hardening and final mechanical characteristics due to the mutual influence of polydiols during crystallization. In the result, the second crystallizing component allows to control amount, structure and quality of crystalline domains in polyurethanes by variation of crystallization conditions.

scholarly journals Synthesis, Characterization, and Thermal Kinetics of Mixed Gadolinium: Calcium Heptamolybdate System

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
R. K. Koul ◽  
Shivani Suri ◽  
Vishal Singh ◽  
K. K. Bamzai
Keyword(s):  
Grown Crystal ◽  
Frequency Factor ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Relevant Model ◽  
X Ray ◽  
Thermoanalytical Techniques ◽  
Thermal Kinetics ◽  
Symmetry Structure ◽  
Kinetics Of

Synthesis of mixed gadolinium calcium heptamolybdate (GdCaHM) system in silica gel medium using single gel single tube technique has been successfully achieved. The grown crystal exhibits various morphologies, which includes spherulites, multifaceted, and square platelets. The nature of the grown material was established by X-ray diffraction (XRD) studies. Fourier transform infrared spectroscopy (FTIR) study signifies the presence of heptamolybdate (Mo7O24) and water symmetry structure, whereas energy dispersive X-ray analysis (EDAX) establishes the stoichiometric of the grown crystal as GdCaMo7O24·8H2O. The thermal behaviour was studied using the thermoanalytical techniques, which include thermogravimetry (TG), differential thermal analysis (DTA), and differential scanning calorimetry (DSC). Results obtained on the application of TG based models, namely, Horowitz-Metzger, Coats-Redfern, and Piloyan-Novikova, suggest the contracting cylindrical model as the relevant model for the thermal decomposition of the material. The kinetic parameters, namely, the order of reaction (n), activation energy (Ea), frequency factor (Z), and entropy (ΔS*), were also calculated using these three models.

On the Mechanism of Milling Induced Disordering in AlFe

1996 ◽  
Vol 460 ◽  
Author(s):  
M. T. Clavaguera-Mora ◽  
J. Zhu ◽  
M. Meyer ◽  
L. Mendoza-Zelis ◽  
F. H. Sanchez ◽  
...  
Keyword(s):  
Long Range ◽  
Milling Time ◽  
Continuous Heating ◽  
X Ray Diffraction ◽  
Mechanical Grinding ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Diffusion Controlled ◽  
Transmission Mössbauer Spectroscopy ◽  
Kinetics Of

ABSTRACTThe evolution of the B2-AlFe phase during mechanical grinding in Ar has been examined as a function of milling time by X-Ray diffraction, transmission Mössbauer spectroscopy and differential scanning calorimetry. Short and long range disorder was observed to increase with the mechanical treatment up to the attainment of a steady state. The evolution of the long range order parameter and of the local atomic configurations at Fe sites were analyzed in terms of possible mechanisms for milling induced disordering. The kinetics of the thermal reordering was studied under continuous heating and isothermal calorimetrie regimes. Modeling of the reordering processes by diffusion controlled growth of pre-existing ordered grains is presented as well as the estimated values of both the enthalpy and the activation energy of the reordering process. The results are consistent with a non uniform distribution of disorder throughout the sample and will be compared with preceding information on related systems.

scholarly journals Microstructure Evolution and Performance Improvement of Hypereutectic Al–Mg2Si Metallic Composite with Ca or Sb

Materials ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 2714
Author(s):  
Min Zuo ◽  
Boda Ren ◽  
Zihan Xia ◽  
Wenwen Ma ◽  
Yidan Lv ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Molar Ratio ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Nucleation Behavior ◽  
X Ray ◽  
Primary Mg2si ◽  
Before And After ◽  
And Performance ◽  
Hardness Values

In this article, the modification effects on Al–Mg2Si before and after heat treatment were investigated with Ca, Sb, and (Ca + Sb). In comparison with single Ca or Sb, the samples with composition modifiers (Ca + Sb) had the optimal microstructure. The sample with a molar ratio for Ca-to-Sb of 1:1 obtained relatively higher properties, for which the Brinell hardness values before and after heat treatment were remarkably increased by 31.74% and 28.93% in comparison with bare alloy. According to differential scanning calorimetry analysis (DSC), it was found that the nucleation behavior of the primary Mg2Si phase could be significantly improved by using chemical modifiers. Some white particles were found to be embedded in the center of Mg2Si phases, which were deduced to be Ca5Sb3 through X-ray diffraction (XRD) and field-emission scanning electron microscope (FESEM) analyses. Furthermore, Ca5Sb3 articles possess a rather low mismatch degree with Mg2Si particles based on Phase Transformation Crystallography Lab software (PTCLab) calculation, meaning that the efficient nucleation capability of Ca5Sb3 for Mg2Si particles could be estimated.

A Model for Formation and Consumption of Transient Phase

2011 ◽  
Vol 172-174 ◽  
pp. 646-651 ◽  
Author(s):  
Gamra Tellouche ◽  
Khalid Hoummada ◽  
Dominique Mangelinck ◽  
Ivan Blum
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Formation ◽  
Transient Phase ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Proposed Model ◽  
Transient Phases ◽  
Kinetics Of

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.

The Effects of Oxidized and Oxide-Free Boron on the Mg-B-H Nanohydrides Transformation in the Nearly Nanosized Powders

2007 ◽  
Vol 128 ◽  
pp. 47-52 ◽  
Author(s):  
R.A. Varin ◽  
Ch. Chiu ◽  
Zbigniew S. Wronski ◽  
Andrzej Calka
Keyword(s):  
Hydrogen Desorption ◽  
Hydrogen Release ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Nanosized Powders ◽  
X Ray ◽  
Milled Sample ◽  
Heat Event ◽  
Reactive Mechanical Alloying ◽  
Type Apparatus

In this work oxidized and oxide-free amorphous boron (a-B) powder and elemental Mg were used in an attempt to directly synthesize the Mg(BH4)2 complex hydride by controlled reactive mechanical alloying (CRMA) under hydrogen in a magneto-mill up to 200h. The particle size was refined to the 100-200nm range. Nanocrystalline MgH2 (~6nm crystallite size) was formed within the particles when an oxidized a-B is used. In contrast, a mixture of MgB2 and an amorphous hydride MgHx was formed when an oxide-free a-B was used. Differential scanning calorimetry (DSC) test up to 500°C produced a single endothermic heat event at 357.7°C due to hydrogen desorption. In addition, desorption conducted in a Sieverts-type apparatus revealed ~1.4wt.% of hydrogen release. The X-ray diffraction pattern after DSC test of the 200h milled sample made with oxide-free boron showed the presence of MgB2.

Hydriding Behaviour of Mg-C Nanocomposites

2003 ◽  
Vol 801 ◽  
Author(s):  
A. Bassetti ◽  
E. Bonetti ◽  
A. L. Fiorini ◽  
J. Grbovic ◽  
A. Montone ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Differential Scanning Calorimetry ◽  
Weight Ratio ◽  
Hydrogen Desorption ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Carbon Nanocomposites ◽  
X Ray ◽  
Scanning Electron

ABSTRACTMagnesium carbon nanocomposites for hydrogen storage have been synthesized by ball milling with different amount of benzene, acting as a lubricant. Their microstructure has been studied by X-ray diffraction and scanning electron microscopy, while the hydrogen desorption temperature has been tested by differential scanning calorimetry. Experimental results show that the microstructure after milling, the hydrogenation capabilities of the material and the reactivity with the air are related to the amount of additives. In particular the carbon to benzene ratio seems to play a major role. In fact, with an optimum value of carbon to benzene weight ratio of 1/6, the amount of carbon being 15 wt% of the milled mixture, a decomposition heat equal to 57% of pure MgH2 was measured, even after air manipulation of the sample.

Sign in / Sign up

Export Citation Format

Share Document