High-entropy carbide ceramics with refined microstructure and enhanced thermal conductivity by the addition of graphite

Wei, Xiaofeng; Liu, Jixuan; Bao, Weichao; Qin, Yuan; Li, Fēi; Liang, Yongcheng; Xu, Fangfang; Zhang, Guojun

doi:10.1016/j.jeurceramsoc.2021.03.053

Cited by 56 publications

(27 citation statements)

References 46 publications

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“…The XRD patterns of the samples prepared by SPS at different temperatures are shown in Figure 1 As reported in our previous study, 39,41 the synthesized HE carbide starting powder has a feature of dual-phase composition, and the high-temperature sintering process will enhance the element diffusion and the solid solution formation processes. However, the present results indicate that the SPS temperature of 1700 • C is not enough high for the formation of a single-phase HE carbide, resulting in broad XRD peaks.…”

Section: Resultssupporting

confidence: 53%

Low‐temperature reactive sintering of carbon vacant high‐entropy carbide ceramics with in‐situ formed silicon carbide

et al. 2021

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It is thought that the sintering of high-entropy (HE) ceramics is generally more difficult when compared to that of the corresponding single-component ceramics. In this paper, we report a novel approach to densify the HE carbide ceramics at relatively low temperatures with a small amount of silicon. Reactive spark plasma sintering (SPS) was used to densify the ceramics using powders of HE carbide and silicon as starting materials. Dense ceramics can be obtained at 1600 -1700 • C. X-ray diffraction analysis reveals that only non-stoichiometric HE carbide phase with carbon vacancy and SiC phase exist in the obtained ceramics. The in-situ formed SiC phase inherits the morphology of the starting silicon powder owing to the slower diffusion of silicon atoms compared to that of the carbon atoms in HE carbide phase. The mechanical properties of the prepared ceramics were preliminarily studied.

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Section: Resultssupporting

confidence: 53%

Low‐temperature reactive sintering of carbon vacant high‐entropy carbide ceramics with in‐situ formed silicon carbide

et al. 2021

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“…A few reports measured the thermal conductivity of both four and five constituent HECs (Table 2). 19,30,31,53 The values indicate that more elements result in a lower thermal conductivity, although other factors such as porosity and carbon content may also affect the reported thermal conductivity.…”

Section: Resultsmentioning

confidence: 99%

“…Figure 6 shows the thermal conductivity of the HEC compared to HfC, TaC (calculated from data gathered in this study), and NbC 0.98 and ZrC 0.92 52 along with the average value predicted using a linear molar ROMs calculation. The thermal conductivity of the HEC (10.7 W/m•K at room temperature and 39.9 ± 2.3 W/m•K at 2000 • C) was noticeably lower than all of the constituent carbides except for TA B L E 2 Thermal conductivity and electrical resistivity of HEC materials 19,30,31,34,53 Author HEC…”

Section: Thermal Conductivitymentioning

confidence: 98%

Thermal and electrical properties of a high entropy carbide (Ta, Hf, Nb, Zr) at elevated temperatures

et al. 2022

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The thermal and electrical properties were measured for a high entropy carbide ceramic, consisting of (Hf, Ta, Zr, Nb)C. The ceramic was produced by spark plasma sintering a mixture of the monocarbides and had a relative density of more than 97.6%. The resulting ceramic was chemically homogeneous as a single‐phase solid solution formed from the constituent carbides. The thermal diffusivity (0.045–0.087 cm2/s) and heat capacity (0.23–0.44 J/g•K) were measured from room temperature up to 2000°C. The thermal conductivity increased from 10.7 W/m•K at room temperature to 39.9 W/m•K at 2000°C. The phonon and electron contributions to the thermal conductivity were investigated, which showed that the increase in thermal conductivity was predominantly due to the electron contribution, while the phonon contribution was independent of temperature. The electrical resistivity increased from 80.9 μΩ•cm at room temperature to 114.1 μΩ•cm at 800°C.

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“…High‐entropy ceramics generally have five or more principal cations and one anion. In recent years, studies on the synthesis of high‐entropy carbide powders, 8–10 densification process, 11 control of microstructures, 12,13 thermal conductivity, 14 and electrical conductivity 15 have achieved significant progress. Zhou et al.…”

Section: Introductionmentioning

confidence: 99%

Ultra‐high strength medium‐entropy (Ti,Zr,Ta)C ceramics at 1800°C by consolidating a core‐shell structured powder

Yang

Wang

et al. 2021

J Am Ceram Soc.

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We report for the first time the synthesis of a core-shell structured composite powder with a core of Zr(Ti,Ta)C and a shell of Ti,Ta(Zr)C at 1700 • C and investigate the formation mechanism for the core-shell structure. The medium-entropy (Ti,Zr,Ta)C ceramics with fine grains (1.1 ± 0.4 μm) and relative density of 94.8% was prepared by hot-pressing at 2100 • C. The flexural strength of (Ti,Zr,Ta)C at 1000 • C (493 ± 21 MPa) was close to the room temperature (511 ± 52 MPa).As the temperature increased from 1600 • C to 1800 • C, the flexural strength was increased significantly, with an ultra-high flexural strength of 725 ± 32 MPa at 1800 • C. The existence of the core-shell structure in the powder suppressed the grain growth due to the sluggish diffusion effect. The ultra-high strength of (Ti,Zr,Ta)C ceramics was attributed to its fine microstructures, high fracture toughness, and the reinforced the grain boundary strength.

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High-entropy carbide ceramics with refined microstructure and enhanced thermal conductivity by the addition of graphite

Cited by 56 publications

References 46 publications

Low‐temperature reactive sintering of carbon vacant high‐entropy carbide ceramics with in‐situ formed silicon carbide

Low‐temperature reactive sintering of carbon vacant high‐entropy carbide ceramics with in‐situ formed silicon carbide

Thermal and electrical properties of a high entropy carbide (Ta, Hf, Nb, Zr) at elevated temperatures

Ultra‐high strength medium‐entropy (Ti,Zr,Ta)C ceramics at 1800°C by consolidating a core‐shell structured powder

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