Pressureless sintering of Ta0.8Hf0.2C UHTC in the presence of MoSi2

Ghaffari, Seyed Amir; Faghihi-Sani, M.A.; Golestani‐Fard, F.; Ebrahimi, Seyed Mohammad

doi:10.1016/j.ceramint.2012.08.050

Cited by 45 publications

(25 citation statements)

References 15 publications

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“…Figure 3 shows that oxidation process of HfC starts at 800 • C. Comparing to the oxidation of pure TaC, the weight increases gradually instead of exhibiting a sharp increase, as evident from the slope. Such behavior is in accordance with the literature description of the oxidation behavior of HfC [12,22]. HfC has the ability to absorb oxygen without transforming into oxide.…”

Section: Mass Change During Thermogravimetric Analysis Of Carbide Solsupporting

confidence: 91%

“…The studies on the solid solutions of TaC-HfC began with the discovery of a TaC0.8HfC0.2 phase that possesses the highest melting point (~4000 °C) of known substances [10]. Preliminary oxidation studies have been carried out on TaC0.8HfC0.2 and HfC-rich compositions, but no improvement in the oxidation behavior was observed compared to pure carbides [11][12][13][14]. Additionally, sintering aids were inevitable in those studies, which introduced secondary phases that clouded the understanding of oxidation behaviors.…”

Section: Introductionmentioning

confidence: 99%

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Thermal Analysis of Tantalum Carbide-Hafnium Carbide Solid Solutions from Room Temperature to 1400 °C

et al. 2017

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Abstract:The thermogravimetric analysis on TaC, HfC, and their solid solutions has been carried out in air up to 1400 • C. Three solid solution compositions have been chosen: 80TaC-20 vol % HfC (T80H20), 50TaC-50 vol % HfC (T50H50), and 20TaC-80 vol % HfC (T20H80), in addition to pure TaC and HfC. Solid solutions exhibit better oxidation resistance than the pure carbides. The onset of oxidation is delayed in solid solutions from 750 • C for pure TaC, to 940 • C for the T50H50 sample. Moreover, T50H50 samples display the highest resistance to oxidation with the retention of the initial carbides. The oxide scale formed on the T50H50 sample displays mechanical integrity to prevent the oxidation of the underlying carbide solid solution. The improved oxidation resistance of the solid solution is attributed to the reaction between Ta 2 O 5 and HfC, which stabilizes the volume changes induced by the formation of Ta 2 O 5 and diminishes the generation of gaseous products. Also, the formation of solid solutions disturbs the atomic arrangement inside the lattice, which delays the reaction between Ta and O. Both of these mechanisms lead to the improved oxidation resistances of TaC-HfC solid solutions.

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Section: Mass Change During Thermogravimetric Analysis Of Carbide Solsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Thermal Analysis of Tantalum Carbide-Hafnium Carbide Solid Solutions from Room Temperature to 1400 °C

et al. 2017

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“…Employing smaller particle size for TaC, high temperature and sintering aid (C, B 4 C, MoSi 2 , TaSi 2 ) are necessary to achieve densities more than 95% by pressureless or hot-press sintering routes. 3,5,[9][10][11] Recently, much attention has been focused on spark plasma sintering (SPS) which uses a pulsed DC current to activate and improve sintering kinetics. In this technique, higher heating rate, lower sintering temperature, and shorter dwelling time are used in comparison with conventional sintering techniques such as hot pressing and pressureless sintering.…”

Section: Introductionmentioning

confidence: 99%

Spark plasma sintering of TaC–HfC UHTC via disilicides sintering aids

Ghaffari

Faghihi-Sani

Golestani‐Fard

et al. 2013

Journal of the European Ceramic Society

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118

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“…Refractory materials require high temperature processes for the formation of materials and products. For example, powder metallurgy requires the sintering temperature of at least 1500°C (usually above 2000°C) for proper microcrystalline powder consolidation [9]. Conventional high temperature and longtime sintering processes can be applicable for coarse-grained materials of micrometer size grains.…”

Section: Introductionmentioning

confidence: 99%

Formation and Properties of the Ta‐Y₂O₃, Ta‐ZrO₂, and Ta‐TaC Nanocomposites

Jakubowicz

Sopata

Adamek

et al. 2018

Advances in Materials Science and Engineering

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e nanocrystalline tantalum-ceramic composites were made using mechanical alloying followed by pulse plasma sintering (PPS). e tantalum acts as a matrix, to which the ceramic reinforced phase in the concentration of 5, 10, 20, and 40 wt.% was introduced. Oxides (Y 2 O 3 and ZrO 2 ) and carbides (TaC) were used as the ceramic phase. e mechanical alloying results in the formation of nanocrystalline grains. e subsequent hot pressing in the mode of PPS results in the consolidation of powders and formation of bulk nanocomposites. All the bulk composites have the average grain size from 40 nm to 100 nm, whereas, for comparison, the bulk nanocrystalline pure tantalum has the average grain size of approximately 170 nm. e ceramic phase refines the grain size in the Ta nanocomposites. e mechanical properties were studied using the nanoindentation tests. e nanocomposites exhibit uniform load-displacement curves indicating good integrity and homogeneity of the samples. Out of the investigated components, the Ta-10 wt.% TaC one has the highest hardness and a very high Young's modulus (1398 HV and 336 GPa, resp.). For the Ta-oxide composites, Ta-20 wt.% Y 2 O 3 has the highest mechanical properties (1165 HV hardness and 231 GPa Young's modulus).

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Pressureless sintering of Ta0.8Hf0.2C UHTC in the presence of MoSi2

Cited by 45 publications

References 15 publications

Thermal Analysis of Tantalum Carbide-Hafnium Carbide Solid Solutions from Room Temperature to 1400 °C

Thermal Analysis of Tantalum Carbide-Hafnium Carbide Solid Solutions from Room Temperature to 1400 °C

Spark plasma sintering of TaC–HfC UHTC via disilicides sintering aids

Formation and Properties of the Ta‐Y₂O₃, Ta‐ZrO₂, and Ta‐TaC Nanocomposites

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Pressureless sintering of Ta0.8Hf0.2C UHTC in the presence of MoSi2

Cited by 45 publications

References 15 publications

Thermal Analysis of Tantalum Carbide-Hafnium Carbide Solid Solutions from Room Temperature to 1400 °C

Thermal Analysis of Tantalum Carbide-Hafnium Carbide Solid Solutions from Room Temperature to 1400 °C

Spark plasma sintering of TaC–HfC UHTC via disilicides sintering aids

Formation and Properties of the Ta‐Y2O3, Ta‐ZrO2, and Ta‐TaC Nanocomposites

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Formation and Properties of the Ta‐Y₂O₃, Ta‐ZrO₂, and Ta‐TaC Nanocomposites