Phase transformations of titanium hydride in thermal desorption process with different heating rates

Ma, Ming; Liang, Li; Wang, Lei; Wang, Yuan; Cheng, Yanlin; Tang, Binghua; Wang, Xiang; Tan, Xiaohua

doi:10.1016/j.ijhydene.2015.05.083

Cited by 53 publications

(21 citation statements)

References 65 publications

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“…The hydrogenation of Ti powder and hBN and their subsequent dehydrogenation during TPD must also be conisdred. Given the compositiono ft he startingm ixture ( % 75 wt %A l, % 5wt% Ti,a nd % 20 wt % hBN), ac omplete mechanochemical conversion of Ti powder to stable TiH 2 and its full dehydrogenation during heatingt o4 00 8C [37,38] is only expected to contribute 0.2 wt %H 2 ,w hich is fully consistent with the corresponding TPD data of 95 wt % hBN and 5wt% Ti in Figure 5. Hence, assuming that hBN is an inactive process controla gent, which also follows from the 95 wt % hBN-5 wt %T id ata of Figure 5, the results presented here indicatea na pproximate 10 %y ield of AlH 3 -derivedm oieties in the presence of titanium under the describede xperimental parameters.…”

Section: Resultssupporting

confidence: 69%

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Towards Direct Synthesis of Alane: A Predicted Defect‐Mediated Pathway Confirmed Experimentally

et al. 2016

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Alane (AlH3) is a unique energetic material that has not found a broad practical use for over 70 years because it is difficult to synthesize directly from its elements. Using density functional theory, we examine the defectmediated formation of alane monomers on Al(111) in a two-step process: (1) dissociative adsorption of H2 and (2) alane formation, which are both endothermic on a clean surface. Only with Ti dopant to facilitate H2 dissociation and vacancies to provide Al adatoms, both processes become exothermic. In agreement, in situ scanning tunneling microscopy showed that during H2 exposure, alane monomers and clusters form primarily in the vicinity of Al vacancies and Ti atoms. Moreover, ball milling of the Al samples with Ti (providing necessary defects) showed a 10 % conversion of Al into AlH3 or closely related species at 344 bar H2, indicating that the predicted pathway may lead to the direct synthesis of alane from elements at pressures much lower than the 104 bar expected from bulk thermodynamics. [d,f] S. Gupta, [a] and V. K. Pecharsky* [a,c] Abstract: Alane (AlH3) is a unique energetic material that has not found broad practical use for over 70 years due to difficulties of its direct synthesis from elements. Using density functional theory we examine the defect-mediated formation of alane monomers on Al(111) in a two-step process: (1) dissociative adsorption of H2 and (2) alane formation; both are endothermic on clean surface. Only with Ti-dopant to facilitate H2 dissociation and vacancy to provide Al adatoms, both processes become exothermic. In agreement, in situ scanning tunnelling microscopy showed that during H2 exposure alane monomers and clusters form primarily in the vicinity of Al vacancies and Ti atoms. Moreover, ball-milling samples of Al with Ti (providing necessary defects) showed a 10% conversion of Al into AlH3 or closely related species at 344 bar H2, indicating that the predicted pathway may lead to direct synthesis of alane from elements at pressures much lower than the 10 4 bar expected from bulk thermodynamics.

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Section: Resultssupporting

confidence: 69%

“…Given the composition of the starting mixture (~75 wt% Al, ~5 wt% Ti and ~20 wt% hBN), a complete mechanochemical conversion of Ti powder to stable TiH2 and its full dehydrogenation during heating to 400 °C [37][38] is only expected to contribute 0.2 wt % H2…”

Section: Resultsmentioning

confidence: 99%

Towards Direct Synthesis of Alane: A Predicted Defect‐Mediated Pathway Confirmed Experimentally

et al. 2016

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“…It is also found that the maximum of H 2 desorption rate for the 500 C preoxidized TiH 2 powders is about 0.9 mg/min, which is larger than that of untreated TiH 2 powders. The heating rates and pre-oxidized temperature have an obvious influence on thermal desorption of TiH 2 [15,16]. The initial desorption temperature is delayed with the heating rates and pre-oxidized temperature increasing, especially the pre-oxidized temperature.…”

Section: Resultsmentioning

confidence: 99%

Deoxidization mechanism of hydrogen in TiH2 dehydrogenation process

Wang

Pan

Zhang

et al. 2016

International Journal of Hydrogen Energy

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“…On the other hand, the shrinkage observed at around 646 ± 0.3 • C reflects the intensive release of hydrogen due to thermally induced dehydrogenation, i.e., decomposition of TiH x . This decomposition is finished before the temperature of 905 • C is reached because TiH x becomes unstable below this temperature [19,20]. This also means that above 905 • C, titanium is available in elemental form.…”

Section: Dilatometric Analysis and Density Changesmentioning

confidence: 99%

In Situ Formation of TiB2 in Fe-B System with Titanium Addition and Its Influence on Phase Composition, Sintering Process and Mechanical Properties

et al. 2019

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Interaction of iron and boron at elevated temperatures results in the formation of an E (Fe + Fe 2 B) eutectic phase that plays a great role in enhancing mass transport phenomena during thermal annealing and therefore in the densification of sintered compacts. When cooled down, this phase solidifies as interconnected hard and brittle material consisting of a continuous network of Fe 2 B borides formed at the grain boundaries. To increase ductile behaviour, a change in precipitates' stoichiometry was investigated by partially replacing iron borides by titanium borides. The powder of elemental titanium was introduced to blend of iron and boron powders in order to induce TiB 2 in situ formation. Titanium addition influence on microstructure, phase composition, density and mechanical properties was investigated. The observations were supported with thermodynamic calculations. The change in phase composition was analysed by means of dilatometry and X-ray diffraction (XRD) coupled with thermodynamic calculations. 235 maximum force (Figure 9a,b) and hence, the TRS as well (Figure 9c). Other additions of titanium (A 236 and B) show intermediate states-samples with 0.47 wt % titanium addition (A) show a decrease of

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Phase transformations of titanium hydride in thermal desorption process with different heating rates

Cited by 53 publications

References 65 publications

Towards Direct Synthesis of Alane: A Predicted Defect‐Mediated Pathway Confirmed Experimentally

Towards Direct Synthesis of Alane: A Predicted Defect‐Mediated Pathway Confirmed Experimentally

Deoxidization mechanism of hydrogen in TiH2 dehydrogenation process

In Situ Formation of TiB2 in Fe-B System with Titanium Addition and Its Influence on Phase Composition, Sintering Process and Mechanical Properties

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