Sintering behaviour, solid solution formation and characterisation of TaC, HfC and TaC–HfC fabricated by spark plasma sintering

Cedillos-Barraza, Omar; Grasso, Salvatore; Nasiri, Nasrin Al; Jayaseelan, Daniel Doni; Reece, Michael J.; Lee, William

doi:10.1016/j.jeurceramsoc.2016.02.009

Cited by 207 publications

(147 citation statements)

References 24 publications

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“…The most common bond coats are those based on metallic MCrAlY alloys (where M=Co, Ni or Ni-Co mixtures) 34 and the basic rule to avoid cracks or delamination between the thermal protective coating on top and the bond coat is the matching of the coefficients of thermal expansion (CTE) of both materials. It has been recently found that the CTE of binary and ternary alloys for the Ta-Hf-C system varies from 7.08 to 7.66·10 −6 /K in the range from 25 to 2000 °C 35 , which match the CTE values for some common MCrAlY alloys in the range of 500 to 700 °C 34 , which is a similar temperature range as the used in this work to study the corrosion behavior of the Ta-Hf-C samples. In addition, the high thermal conductivities reported for TaC 36 and Ta-Hf-C 35 carbides ensure an enhanced heat dissipation for applications that requires working at high temperatures such as turbine blades or hypersonic flights 35 .…”

Section: Resultssupporting

confidence: 72%

Robust tribo-mechanical and hot corrosion resistance of ultra-refractory Ta-Hf-C ternary alloy films

Yate

Coy

Aperador

2017

Sci Rep

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In this work we report the hot corrosion properties of binary and ternary films of the Ta-Hf-C system in V2O5-Na2SO4 (50%wt.-50%wt.) molten salts at 700 °C deposited on AISI D3 steel substrates. Additionally, the mechanical and nanowear properties of the films were studied. The results show that the ternary alloys consist of solid solutions of the TaC and HfC binary carbides. The ternary alloy films have higher hardness and elastic recoveries, reaching 26.2 GPa and 87%, respectively, and lower nanowear when compared to the binary films. The corrosion rates of the ternary alloys have a superior behavior compared to the binary films, with corrosion rates as low as 0.058 μm/year. The combination and tunability of high hardness, elastic recovery, low nanowear and an excellent resistance to high temperature corrosion demonstrates the potential of the ternary Ta-Hf-C alloy films for applications in extreme conditions.

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Section: Resultssupporting

confidence: 72%

Robust tribo-mechanical and hot corrosion resistance of ultra-refractory Ta-Hf-C ternary alloy films

Yate

Coy

Aperador

2017

Sci Rep

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“…Melting of HfC 0.98 samples was also achieved with intermediate and short pulses. The lower thermal diffusivity24 of HfC compared to TaC produces higher heat concentration in the sample surface, producing higher temperatures at lower applied power. Furthermore, much less vaporisation was observed in pure hafnium carbide compared with all of the other compositions, judging from the size of the vapour plume traces visible on the sample holder above the sample after the melting experiments.…”

Section: Resultsmentioning

confidence: 99%

Investigating the highest melting temperature materials: A laser melting study of the TaC-HfC system

Cedillos-Barraza

Manara

Boboridis

et al. 2016

Sci Rep

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162

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TaC, HfC and their solid solutions are promising candidate materials for thermal protection structures in hypersonic vehicles because of their very high melting temperatures (>4000 K) among other properties. The melting temperatures of slightly hypostoichiometric TaC, HfC and three solid solution compositions (Ta1−xHfxC, with x = 0.8, 0.5 and 0.2) have long been identified as the highest known. In the current research, they were reassessed, for the first time in the last fifty years, using a laser heating technique. They were found to melt in the range of 4041–4232 K, with HfC having the highest and TaC the lowest. Spectral radiance of the hot samples was measured in situ, showing that the optical emissivity of these compounds plays a fundamental role in their heat balance. Independently, the results show that the melting point for HfC0.98, (4232 ± 84) K, is the highest recorded for any compound studied until now.

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“…Diffractions of Cu were barely observable, while ZrC phase was absent in the consolidated ceramic. The dominant XRD peaks from the consolidated ceramic were indexed by TaC with significant broadening and shift towards lower 2 positions, indicating formation of a (Ta, Zr)C ss [18,19]. SEM of the polished-and-thermally etched surface (not shown) revealed uniform equiaxed grains having an average diameter from ∼0.9 to 6.4 m.…”

Section: General Observationmentioning

confidence: 99%

Nano-(Ta, Zr)C Precipitates at Multigrain Conjunctions in TaC Ceramic with 10 mol% ZrC and 5 mol% Cu as Sintering Aid

Zhong

Geng

Wang

et al. 2018

Journal of Nanomaterials

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A fully dense TaC ceramic was prepared by hot pressing using 10 mol% ZrC plus 5 mol% Cu as a sintering aid. Formation of (Ta, Zr)C solid solution (ss) by reaction between TaC and ZrC facilitated densification. Addition of Cu refined the microstructure and consequently improved flexural strength of the TaC ceramics. TEM investigation found ubiquitous precipitation of nanocrystallites at multigrain conjunctions. The nanocrystallites were (Ta, Zr)C solid solution with uniform dispersion in an oxygen-rich glassy matrix. Although formation of nanoprecipitates may not much affect the mechanical properties of the TaC ceramic, the structure suggested a new type of nanoceramic worth further research.

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Sintering behaviour, solid solution formation and characterisation of TaC, HfC and TaC–HfC fabricated by spark plasma sintering

Cited by 207 publications

References 24 publications

Robust tribo-mechanical and hot corrosion resistance of ultra-refractory Ta-Hf-C ternary alloy films

Robust tribo-mechanical and hot corrosion resistance of ultra-refractory Ta-Hf-C ternary alloy films

Investigating the highest melting temperature materials: A laser melting study of the TaC-HfC system

Nano-(Ta, Zr)C Precipitates at Multigrain Conjunctions in TaC Ceramic with 10 mol% ZrC and 5 mol% Cu as Sintering Aid

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