Kinetic study on nonisothermal dehydrogenation of TiH2 powders

Liu, H.; He, Peng; Feng, Jie; Cao, Jian

doi:10.1016/j.ijhydene.2009.01.095

Cited by 114 publications

(67 citation statements)

References 44 publications

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“…Table 1 shows the list of activation energy for each step which is related to the activation energy of decomposition of hydride phase. The activation energy of transformation of  to  is about 134 kJ/mol which is in agreement with the previous investigation by Liu who did model TiH2 dehydrogenation [6].…”

Section: Thermal Desorption Studies In Vacuumsupporting

confidence: 91%

“…At the end of 50 s, Haag & Shipko [5] showed through a pressure-compositiontemperature (PCT) experiment that titanium has two equilibrium plateau pressure related to the transformation of -Ti(HCP) to -TiHx (BCC), and the -TiHx to -TiH2(FCC). Recently, the most studies focused on kinetics observation by thermal or spectroscopy methods, for example in [6,7]. Kenedy & Lopez [8] observed that titanium dihydrides desorbed hydrogen in two steps.…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of Hydrogen Absorption and Desorption in Titanium

Suwarno

Yartys

2017

Bull. Chem. React. Eng. Catal.

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Titanium is reactive toward hydrogen forming metal hydride which has a potential application in energy storage and conversion. Titanium hydride has been widely studied for hydrogen storage, thermal storage, and battery electrodes applications. A special interest is using titanium for hydrogen production in a hydrogen sorption-enhanced steam reforming of natural gas. In the present work, nonisothermal dehydrogenation kinetics of titanium hydride and kinetics of hydrogenation in gaseous flow at isothermal conditions were investigated. The hydrogen desorption was studied using temperature desorption spectroscopy (TDS) while the hydrogen absorption and desorption in gaseous flow were studied by temperature programmed desorption (TPD). The present work showed that the path of dehydrogenation of the TiH2 is  hydride phase with possible overlapping steps occurred. The fast hydrogen desorption rate observed at the TDS main peak temperature were correlated with the fast transformation of the TiH1.41 to TiH0.59. In the gaseous flow, hydrogen absorption and desorption were related to the transformation of TiH0.59  TiH1.41 with 2 wt.% hydrogen reversible content.

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Section: Thermal Desorption Studies In Vacuumsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Kinetics of Hydrogen Absorption and Desorption in Titanium

Suwarno

Yartys

2017

Bull. Chem. React. Eng. Catal.

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“…Additionally, although in situ high temperature XRD and X-ray synchrotron/neutron diffraction techniques were applied, their results may still be of concern. First, some experiments were conducted in argon atmosphere [32,33,35], which possibly causes the oxidation problem and may mislead the result. Moreover, other reports using vacuum atmosphere may result in instant information loss or delay due to the fact that XRD scanning required a long time (usually several minutes to one hour to achieve a complete scan) [31,34].…”

Section: Dehydrogenation Processmentioning

confidence: 99%

An in situ Study of NiTi Powder Sintering Using Neutron Diffraction

Chen

Liss

Cao

2015

Metals

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This study investigates phase transformation and mechanical properties of porous NiTi alloys using two different powder compacts (i.e., Ni/Ti and Ni/TiH2) by a conventional press-and-sinter means. The compacted powder mixtures were sintered in vacuum at a final temperature of 1373 K. The phase evolution was performed by in situ neutron diffraction upon sintering and cooling. The predominant phase identified in all the produced porous NiTi alloys after being sintered at 1373 K is B2 NiTi phase with the presence of other minor phases. It is found that dehydrogenation of TiH2 significantly affects the sintering behavior and resultant microstructure. In comparison to the Ni/Ti compact, dehydrogenation occurring in the Ni/TiH2 compact leads to less densification, yet higher chemical homogenization, after high temperature sintering but not in the case of low temperature sintering. Moreover, there is a direct evidence of the eutectoid decomposition of NiTi at ca. 847 and 823 K for Ni/Ti and Ni/TiH2, respectively, during furnace cooling. The static and cyclic stress-strain behaviors of the porous NiTi alloys made from the Ni/Ti and Ni/TiH2 compacts were also investigated. As compared with the Ni/Ti sintered samples, OPEN ACCESSMetals 2015, 5 531 the samplessintered from the Ni/TiH2 compact exhibited a much higher porosity, a higher close-to-total porosity, a larger pore size and lower tensile and compressive fracture strength.

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“…Its transformation is dependent on atmosphere, heating rate, and powder size (if TiH 2 in present as powder), as well as temperature. [1][2][3] TiH 2 has attracted extensive research interest for applications in hydrogen storage, [4] metal foaming, [5] and hydroprocessing. [6] In the context of powder metallurgy (PM), research on TiH 2 was initiated in the 1960s [7] but recent years have seen a significant renewed interest in PM TiH 2 for a few good reasons, including [8][9][10][11][12][13] : (a) the use of TiH 2 powder can result in higher sintered densities and often better mechanical properties; (b) TiH 2 powder can be more affordable than the hydride-dehydride (HDH) Ti powder; and (c) the use of TiH 2 powder can lead to lower oxygen content in as-sintered Ti materials.…”

mentioning

confidence: 99%

“…[31] However, the equilibrium eutectoid structure (b-Ti fi a-Ti + TiFe) assumed by the Ti-Fe phase diagram (Figure 4b) [32] has rarely been observed in PM (Ti-riched) Ti-Fe alloys due to the sluggish eutectoid reaction rate involved. The formation of the oxygen-stabilised Ti 4 Fe 2 O phase in the TiH 2 -6Al-4V (40°C/min) may indicate that accelerated reactions between Ti and Fe have occurred due to the use of TiH 2 as well as the high heating rate employed.…”

mentioning

confidence: 99%

In Situ Synchrotron Radiation Study of TiH2-6Al-4V and Ti-6Al-4V: Accelerated Alloying and Phase Transformation, and Formation of an Oxygen-Enriched Ti4Fe2O Phase in TiH2-6Al-4V

Yan

Dargusch

Kong

et al. 2014

Metall Mater Trans A

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In situ heating, synchrotron radiation X-ray diffraction has been used to study the alloying and phase transformation behavior of TiH 2 -6Al-4V and Ti-6Al-4V alloys. Accelerated alloying and phase transformation were observed in the powder compact of the TiH 2 -6Al-4V alloy subjected to a high heating rate. In addition, an oxygen-stabilized Ti 4 Fe 2 O phase, which is present as sub-micron or nanoscaled particles, has been identified in the TiH 2 -6Al-4V alloy. The implications of these experimental findings have been discussed in terms of alloying, improved densification and oxygen scavenging in titanium and titanium alloys. Titanium hydride, normally referred to as the d-TiH 2 phase [face-centred cubic (fcc) with a = 4.36 Å ], is a compound stable at room temperature (RT) but will decompose at elevated temperatures. Its transformation is dependent on atmosphere, heating rate, and powder size (if TiH 2 in present as powder), as well as temperature. [1][2][3] TiH 2 has attracted extensive research interest for applications in hydrogen storage, [4] metal foaming, [5] and hydroprocessing. [6] In the context of powder metallurgy (PM), research on TiH 2 was initiated in the 1960s [7] but recent years have seen a significant renewed interest in PM TiH 2 for a few good reasons, including [8][9][10][11][12][13] : (a) the use of TiH 2 powder can result in higher sintered densities and often better mechanical properties; (b) TiH 2 powder can be more affordable than the hydride-dehydride (HDH) Ti powder; and (c) the use of TiH 2 powder can lead to lower oxygen content in as-sintered Ti materials. This is due to the release of atomic hydrogen after heating of TiH 2 , which can reduce the surface oxide film on the TiH 2 powder particles. As a result of these benefits, PM TiH 2 shows promise as means to develop more affordable, high-performance PM titanium alloys.The dehydrogenation of TiH 2 involves a number of phase transformations according to the reassessed phase diagram of Ti-H.[14] A shell of a phase was found to envelop each remaining core of titanium hydride particle.[1] This envelope of a phase not only controls the kinetics of dehydrogenation but is also expected to affect the alloying process of b-stabilizers.[1] Ivasishin and Savvakin [15] first proposed that the use of a fast heating rate could avoid the formation of this a shell during the decomposition of TiH 2 ; doing so is expected to favor the alloying process with b-stabilizers as the a shell acts as a barrier to the diffusion of b-stabilizers. This represents another potential unique feature of the PM TiH 2 but no direct evidence has been reported yet. One reason is that most relevant studies including the sintering of titanium alloys using TiH 2 powder were carried out at heating rates of less than 30°C/min, [3,8,[10][11][12][13] which has been shown to be inadequate to avoid the formation of the a phase. [3] The other reason is that it requires the use of in situ, instantaneous and high-temperature phase identification to monitor phase transformation du...

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Kinetic study on nonisothermal dehydrogenation of TiH2 powders

Cited by 114 publications

References 44 publications

Kinetics of Hydrogen Absorption and Desorption in Titanium

Kinetics of Hydrogen Absorption and Desorption in Titanium

An in situ Study of NiTi Powder Sintering Using Neutron Diffraction

In Situ Synchrotron Radiation Study of TiH2-6Al-4V and Ti-6Al-4V: Accelerated Alloying and Phase Transformation, and Formation of an Oxygen-Enriched Ti4Fe2O Phase in TiH2-6Al-4V

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