Enthalpies of formation of hafnium carbides

Kornilov, A. N.; Chelovskaya, N.V.; Zhelankin, V.I.; Швейкин, Г. П.

doi:10.1016/0021-9614(77)90088-x

Cited by 13 publications

(9 citation statements)

References 3 publications

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“…Removal of oxygen from the oxycarbide is assisted by a higher reaction temperature or additional heat treatments. The progress of the reaction after oxide removal can be monitored by oxygen solubility in the oxycarbide and this is determined by lattice parameter . Therefore, the sol–gel‐derived reaction included both the reduction in zirconia and the removal of oxygen from the oxycarbide.…”

Section: Resultsmentioning

confidence: 99%

“…The progress of the reaction after oxide removal can be monitored by oxygen solubility in the oxycarbide and this is determined by lattice parameter. 27,28 Therefore, the sol-gel-derived reaction included both the reduction in zirconia and the removal of oxygen from the oxycarbide. The nanoparticles in close proximity to carbon are likely responsible for the low-temperature conversion of ZrO 2 into ZrC.…”

Section: Resultsmentioning

confidence: 99%

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Synthesis and Evolution of Zirconium Carbide via Sol–Gel Route: Features of Nanoparticle Oxide–Carbon Reactions

et al. 2013

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A sol–gel route was used to synthesize nanocrystalline zirconium carbide (ZrC). The starting materials were zirconium propoxide, with carbon introduced by furfuryl alcohol (FA). A block copolymer surfactant was used to homogenize the oxide and carbon components. ZrC was produced at a low temperature of 1250°C and complete conversion achieved at 1450°C. The powder was nanocrystalline size less than 100 nm. Phase changes were studied using X‐ray diffraction and Raman spectroscopy. Rietveld analysis followed the changes in crystallite size and lattice parameters of the phases during carbothermal reduction. Morphology changes were observed using nitrogen gas sorption. High‐resolution TEM and EDS were used to image the carbide lattice, surface oxides, and graphene‐like carbons. The results indicate that nanoparticle carbothermal synthesis involves agglomeration and necking as the most viable mode of mass transport to complete the carbothermal reduction.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Synthesis and Evolution of Zirconium Carbide via Sol–Gel Route: Features of Nanoparticle Oxide–Carbon Reactions

et al. 2013

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“…Our aim here is to aid future experimental work, ab initio computations and Calphad optimizations by bringing to light to some relevant data which are often omitted, e.g., formation enthalpies for oxycarbides measured by Kornilov [125], work of Turchanin [30] on compositional dependence of high temperature heat capacity of carbonitrides, and Brundiers [126] work on Hf oxycarbonitrides. We also want to highlight very recent developments, such as the application of the impulse current heating method to measure high-temperature heat capacities and fusion enthalpies for zirconium carbonitrides and ab initio computations of the fusion enthalpies and melting temperatures in the Hf-C-N system.…”

Section: Rocksalt (Oxy)carbonitridesmentioning

confidence: 99%

“…They confirmed the higher solubility of oxygen in ZrC relative to HfC but reported much lower limits: x = 0.26 for ZrC 1−x O x at 1850 °C and x = 0.10 for HfC 1−x O x at 1750 °C. Kornilov et al [136] performed a characterization of Hf oxycarbides (Table S3) for the purpose of formation enthalpy determination and reported a maximum oxygen content of x = 0.15 in the substoichiometric HfC 0.6 O 0.15 composition.…”

Section: Rocksalt (Oxy)carbonitridesmentioning

confidence: 99%

“…Note that in Rejasse’s [113] experiments, the samples were synthesized by a carbothermic reduction of oxides with amorphous carbon, which rules out deficiency on the non-metal sublattice. Constant [114,135] and Kornilov [136] both reported higher oxygen dissolution limits in Zr and Hf rocksalt oxycarbides. They used metallic Zr and Hf in the synthesis, thus making metal-rich compositions possible.…”

Section: Rocksalt (Oxy)carbonitridesmentioning

confidence: 99%

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Carbides and Nitrides of Zirconium and Hafnium

et al. 2019

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Among transition metal carbides and nitrides, zirconium, and hafnium compounds are the most stable and have the highest melting temperatures. Here we review published data on phases and phase equilibria in Hf-Zr-C-N-O system, from experiment and ab initio computations with focus on rocksalt Zr and Hf carbides and nitrides, their solid solutions and oxygen solubility limits. The systematic experimental studies on phase equilibria and thermodynamics were performed mainly 40–60 years ago, mostly for binary systems of Zr and Hf with C and N. Since then, synthesis of several oxynitrides was reported in the fluorite-derivative type of structures, of orthorhombic and cubic higher nitrides Zr3N4 and Hf3N4. An ever-increasing stream of data is provided by ab initio computations, and one of the testable predictions is that the rocksalt HfC0.75N0.22 phase would have the highest known melting temperature. Experimental data on melting temperatures of hafnium carbonitrides are absent, but minimum in heat capacity and maximum in hardness were reported for Hf(C,N) solid solutions. New methods, such as electrical pulse heating and laser melting, can fill the gaps in experimental data and validate ab initio predictions.

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Phase Diagrams of Metal–Carbon and Metal–Nitrogen Systems and Ordering in Strongly Nonstoichiometric Carbides and Nitrides

Гусев

Rempel

1997

phys. stat. sol. (a)

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Enthalpies of formation of hafnium carbides

Cited by 13 publications

References 3 publications

Synthesis and Evolution of Zirconium Carbide via Sol–Gel Route: Features of Nanoparticle Oxide–Carbon Reactions

Synthesis and Evolution of Zirconium Carbide via Sol–Gel Route: Features of Nanoparticle Oxide–Carbon Reactions

Carbides and Nitrides of Zirconium and Hafnium

Phase Diagrams of Metal–Carbon and Metal–Nitrogen Systems and Ordering in Strongly Nonstoichiometric Carbides and Nitrides

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