Synthesis and characterization of hafnium carbide fine powders

Matović, Branko; Babić, Biljana; Bucevac, Dusan; Čebela, Maria; Maksimović, Vesna; Pantić, Jelena; Miljković, Miomir

doi:10.1016/j.ceramint.2012.06.083

Cited by 25 publications

(18 citation statements)

References 11 publications

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“…At 1475 C, the crystallite size ($50 nm) was determined from XRD spectra using the Scherrer Equation. More recently, 100-200 nm grain size carbides (pure at $97%) were obtained by pyrolysing HfCl 4 and citric acid monohydrate 12 at 1600 C and near-stoichiometric carbides with sub-micron grain sizes were fabricated 13 by using a method of the electrodeoxidation of hafnium dioxide (HfO 2 ) and graphite powder.…”

Section: Introductionmentioning

confidence: 99%

TEM study of the reaction mechanisms involved in the carbothermal reduction of hafnia

et al. 2015

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International audienceThe synthesis of HfCxOy oxycarbides through the carbothermal reaction of hafnia with carbon black was undertaken. The obtained powders at different rates of advancement were studied by TEM and XRD in order to investigate the reaction mechanisms involved during such a transformation. The contact between the two starting reactants is shown to be non-reactive, attesting to the transformation operating through solid–gas reactions. The hafnia phase is destabilized by the CO(g) rich atmosphere and is consumed by the migration of ledges at the surface of the crystals acting as a zipper mechanism that liberates HfO(g) and CO2(g) species. The carbon dioxide thus released is used in return to oxidize the carbon black forming carbon monoxide through the Boudouard equilibrium. The liberated HfO(g) then reacts with the ambient CO(g) to form the oxycarbide phase which is shown to nucleate in the carbon black areas. The oxycarbide nuclei display a core–shell microstructure which is formed by a single crystal core embedded in an oxygen rich amorphous phase. During the final stage of the reaction, the atmosphere, which, saturated in CO(g), progressively reduces the oxygen rich gangue until it finally disappears. The accurate determination of the cell parameter of the oxycarbide phase during the reaction indicates that the first formed compound is nearly saturated in carbon, comparable to the metallic carbide. The small change in the lattice parameter indicates that the chemical composition is very restricted, so the solid solution of oxygen within the hafnium oxycarbide seems to be very limited

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Section: Introductionmentioning

confidence: 99%

TEM study of the reaction mechanisms involved in the carbothermal reduction of hafnia

et al. 2015

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“…Hafnium carbide (HfC) exhibits high thermodynamic stability with a melting point of ~3900°C, high hardness and Young’ s modulus, as well as good thermomechanical properties at ultra high temperature . Therefore, it is considered as a promising material for applications of high‐temperature electrodes, cutting tools, rocket nozzles, nuclear reactor rods, space/air craft and thermal‐field emitters Nevertheless, HfC exhibits a low fracture toughness (1.73‐3.40 MPa m 1/2 ), which can limit its structural applications in extreme environments . An effective way to enhance the fracture toughness of HfC is to incorporate secondary phase materials, such as silicon carbide (SiC) rods, BN, SiC ceramics, refractory metal (Tungsten) to form cermets and other high‐temperature carbides, as attempted in some previous studies .…”

Section: Introductionmentioning

confidence: 99%

High fracture toughness of HfC through nano‐scale templating and novel sintering aids

Hao

Guo

et al. 2018

J Am Ceram Soc

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An approach to improve the sintering ability and the fracture toughness of hafnium carbide (HfC) ceramic by designing a unique composite structure is reported. The uniform and ultra‐fine HfC nanoparticles (~300 nm) are synthesized at 1450°C by vacuum carbonization reaction with the glucose‐derived hydrothermal precursor as a carbon source and template. HfC ceramic sintered with a SiCN sintering aid of 15 vol. % possesses a beneficial three‐dimensional network microstructure composed of inter‐penetrating phases of carbon, SiC and HfC with varied stoichiometry at multi‐length scales. The obtained HfC exhibits a higher fracture toughness of 5.5 MPa m1/2, which can be attributed to the unique composite structure able to promote stress releases in the crack tip and enhance the resistance to crack propagation.

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“…5 Conventionally, HfC can be synthesized by various methods including solid state combustion via direct combination of the elements at elevated temperatures, chemical vapor deposition, carbothermal reduction of metal oxides, sol-gel route, laser and plasma chemical synthesis, etc. [6][7][8][9][10] Solution-based processing possesses the advantages of forming a homogenous distribution of all elements on a molecular level, which can reduce the kinetic barriers and lower the reaction temperatures, thus leading to ne size of the synthesized particles. [11][12][13] Moreover, it has great potential to be used as facile precursor for the fabrication of continuous bers reinforced HfC ceramic matrix composites.…”

Section: Introductionmentioning

confidence: 99%

Synthesis and characterization of nano-crystalized HfC based on an aqueous solution-derived precursor

Jiang

Ding

et al. 2018

RSC Adv.

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Synthesis and characterization of hafnium carbide fine powders

Cited by 25 publications

References 11 publications

TEM study of the reaction mechanisms involved in the carbothermal reduction of hafnia

TEM study of the reaction mechanisms involved in the carbothermal reduction of hafnia

High fracture toughness of HfC through nano‐scale templating and novel sintering aids

Synthesis and characterization of nano-crystalized HfC based on an aqueous solution-derived precursor

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