Kinetics of thermal decomposition of niobium hydride

Gabriel, Sinara Borborema; Brum, Mariana Coutinho; Candioto, Katia Cristiane Gandolpho; Sandim, Hugo Ricardo Zschommler; Suzuki, Paulo Atsushi; Nunes, Carlos Ângelo

doi:10.1016/j.ijrmhm.2011.06.012

Cited by 17 publications

(9 citation statements)

References 13 publications

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“…8. First of all, the G/B values of FCC NbH 2 and FCO NbH 1 are bigger than those of the other phases and close to the critical value of 0.57, suggesting that these two phases should be brittle, which matches well with similar experimental observations in the literature [16,19,21,22]. Second, among all the niobium dihydrides, the NbH 1.5 stoichiometry should be the most ductile one with the lowest G/B values, and such a softening seems compatible with the minimum values of G and E shown in Fig.…”

Section: Mechanical Propertiessupporting

confidence: 90%

“…4 that for each of the NbH 1 and NbH 1.25 phases, the FCO structure has a much lower DH f value than the FCC structure, and slightly smaller than the FCT structure. It follows that the FCO structure of NbH 1 and NbH 1.25 is energetically more favorable and more likely to be formed in real situations, which is in excellent agreement with the experimentally obtained FCO structure of the NbH 1 phase by several groups [17,19,21,22,28,29]. In other words, the descending sequence of phase stability of both NbH 1 and NbH 1.25 is as follows: FCO / FCT / FCC, which is the opposite of the descending sequence of atomic volume listed in Fig.…”

Section: Phase Stabilitysupporting

confidence: 87%

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Phase stability and mechanical properties of niobium dihydride

Long

Gong

2014

International Journal of Hydrogen Energy

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Section: Mechanical Propertiessupporting

confidence: 90%

Section: Phase Stabilitysupporting

confidence: 87%

Phase stability and mechanical properties of niobium dihydride

Long

Gong

2014

International Journal of Hydrogen Energy

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“…can be changed with the particle size. In particular, the dehydrogenation temperature presented by Gabrial et al 26) , was for the NbH powder with particle size approximately 20 µm, whereas in the present study the particle size of niobium hydride, formed due to mechano-chemical reaction during mechanical milling, is almost in the nanometer size range. Therefore, it can be presumed that dehydrogenation of niobium hydride particles, present in the MMed powders (72 ks and 180 ks), would start and complete at lower temperatures due to relatively smaller particle sizes, as compared to those reported for the comparatively coarser particle size.…”

Section: Thermal Analysiscontrasting

confidence: 56%

“…The results reported by Bhosle et al 25) are in good agreement with the results shown in the present study. Similar to the dehydrogenation of titanium hydride powder, niobium hydride also can be dehydrogenated at approximately 653 K-763 K 26) . It is also shown above that the dehydrogenation temperature of a particular hydride depends on the powder particle size, i.e.…”

Section: Thermal Analysismentioning

confidence: 98%

Synthesis of Ternary Ti-25Nb-11Sn Alloy by Powder Metallurgy Route Using Titanium Hydride Powder

2016

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In the present work, Ti-25Nb-11Sn (mass%) alloys were successfully prepared by an advanced powder metallurgy method. The alloys were synthesized by mechanical milling of powder mixture, consisting of titanium hydride (TiH 2 ), elemental niobium (Nb) and elemental tin (Sn) powders, followed by their consolidation via Spark Plasma Sintering (SPS) method. The use of brittle TiH 2 powder, instead of ductile elemental Ti powder, resulted in ~100% powder yield of mechanically milled (MMed) powder even after long time mechanical milling. The resulting MMed powders consisted of homogeneously distributed nano-sized titanium/niobium hydride powder particles together with a few micron-sized pure Nb particles. The mechanical milling also led to the lowering of dehydrogenation temperature of the hydride particles. Sintering of short time mechanically milled powder (72 ks) resulted in the ne-grained heterogeneous microstructure consisting of β phase and orthorhombic martensitic α phase. On the other hand, sintering of long time mechanically milled powder (180 ks) resulted in the evolution of β-phase and α-phase. The specimen containing α+β phase exhibited higher average hardness as compared to the average hardness of specimen containing α +β phase.

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“…No residual NbH 2 , Nb, or C phases were observed by XRD in the sintered cermets. During sintering, complete decomposition of NbH 2 into Nb and H 2 was reported to be below 500 • C, whereas the densification of the powder compacts had not started [25]. The generated H 2 was therefore removed from the powder compact under vacuum atmosphere.…”

Section: Influence Of Carbon Content In Nbc-12 Vol % Ni Cermetsmentioning

confidence: 99%

Effect of Carbon Content on the Microstructure and Mechanical Properties of NbC-Ni Based Cermets

Huang

Baets

Sukumaran

et al. 2018

Metals

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Abstract:The aim of this work was to correlate the overall carbon content in NbC-Ni, NbC-Ni-VC and NbC-Ni-Mo starting powders with the resulting microstructure, hardness, and fracture toughness of Ni-bonded NbC cermets. A series of NbC-Ni, NbC-Ni-VC and NbC-Ni-Mo cermets with different carbon content were prepared by conventional liquid phase sintering for 1 h at 1420 • C in vacuum. Microstructural analysis of the fully densified cermets was performed by electron probe microanalysis (EPMA) to assess the effect of carbon and VC or Mo additions on the NbC grain growth and morphology. A decreased carbon content in the starting powder mixtures resulted in increased dissolution of Nb, V, and Mo in the Ni binder and a decreased C/Nb ratio in the NbC based carbide phase. The Vickers hardness (HV 30 ) and Palmqvist indentation toughness were found to decrease significantly with an increasing carbon content in the Mo-free cermets, whereas an antagonistic correlation between hardness and toughness was obtained as a function of the Mo-content in Mo-modified NbC cermets. To obtain optimized mechanical properties, methods to control the total carbon content of NbC-Ni mixtures were proposed and the prepared cermets were investigated in detail.

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Kinetics of thermal decomposition of niobium hydride

Cited by 17 publications

References 13 publications

Phase stability and mechanical properties of niobium dihydride

Phase stability and mechanical properties of niobium dihydride

Synthesis of Ternary Ti-25Nb-11Sn Alloy by Powder Metallurgy Route Using Titanium Hydride Powder

Effect of Carbon Content on the Microstructure and Mechanical Properties of NbC-Ni Based Cermets

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