Formation and Stability of Metastable Tungsten Carbide Nanoparticles

Kolel-Veetil, Manoj K.; Goswami, R.; Fears, Kenan P.; Qadri, S. B.; Lambrakos, S. G.; Laskoski, Matthew; Keller, Teddy M.; Saab, Andrew P.

doi:10.1007/s11665-015-1476-3

Cited by 10 publications

(3 citation statements)

References 24 publications

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“…We next compared these results to phase transitions observed in the literature. Transitions of γ-W 2 C, ε-W 2 C, and α-W 2 C , to the δ-WC phase have been demonstrated, and Rodella et al reported a method to stop the phase transition of W 2 C (unreported phase) to δ-WC by using a Ni promoter. A two-step transition of γ-WC to W 2 C (hexagonal phase, likely ε-W 2 C, but sufficient detail to confirm was not provided) that proceeds to the δ-WC phase has been experimentally observed .…”

Section: Resultsmentioning

confidence: 99%

Nanoparticle Size Effects on Phase Stability for Molybdenum and Tungsten Carbides

et al. 2021

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Transition-metal carbides (TMCs) are important materials for a variety of applications and industrial processes, in part because of their variable crystal structures and surfaces. However, the synthesis of TMCs often proceeds through metastable phases during particle growth, the appearance of which cannot be described by traditional phase diagrams. Here, we use density functional theory calculations and thermodynamic analyses to construct particle size-dependent phase diagrams for Mo and W carbides and reveal the relationships between phase stability and TMC nanoparticle size. We compute size-dependent phase diagrams for a wide range of Mo carbide and W carbide phases, determine predicted crystallization pathways during synthesis, and compare model results with experimental data. We provide insights for the influence of nanoparticle size on TMC nucleation and growth during synthesis and provide a computationally guided road map for navigating the synthesis of target TMC surfaces and phases.

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Section: Resultsmentioning

confidence: 99%

Nanoparticle Size Effects on Phase Stability for Molybdenum and Tungsten Carbides

et al. 2021

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“…This approach yields monocrystalline and chemically pure ceramics, and the leftover free carbon in the ceramic matrix functionally inhibits grain growth. To date, this process has been implemented to synthesize titanium carbide (TiC), 32 silicon carbide (SiC), 33 tungsten carbide (WC), 34 niobium carbide (NbC), 35 and tantalum carbide (TaC) monoliths 36 . This approach allowed rapid synthesis (<48 h end‐to‐end), relied on readily available precursor compositions, and implemented inexpensive, safe, and commercially scalable manufacturing equipment.…”

Section: Introductionmentioning

confidence: 99%

Synthesis, structure, and properties of polymer‐derived, metal‐reinforced boron carbide cermet composites

Dyatkin

Laskoski

Edelen

et al. 2020

Int J Applied Ceramic Tech

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We report on a novel polymer‐derived synthesis approach that yields boron carbide monoliths and metal‐reinforced B4C cermets. This single‐step approach relies on a preceramic powder blend of boron and an acetylenic resin with a high char yield. At low temperatures below 1500°C and without applied pressures, preceramic precursor reaction bond together and form nanocrystalline refractory B4C matrices. Resulting near net shape boron, carbide monoliths exhibit small crystal grain sizes, maintain chemical purity, and exhibit morphological homogeneity. We reinforce the refractory carbide with five different metals and demonstrate the influence of each on the density, hardness, oxidation stability, and electronic conductivity of resulting cermet composites. We assess the optimal synthesis and reinforcement strategies that tailor these nanostructured materials for inexpensive and high‐performing engineering applications.

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“…Coupled with its low viscosity and fast gelation, the large cure exotherm of TPEB hinders its applicability as a matrix resin in fiber‐reinforced composites . Yet, TPEB has found application as the carbon source for the synthesis of a variety of refractory ceramics because of its exceptionally high char yield (~83%) where the resin is only a small portion of a larger formulation …”

Section: Introductionmentioning

confidence: 99%

Oligomeric phthalonitriles and tetrakis(phenylethynyl)benzene blends with improved processing and thermal properties

Butler

Alden

Taylor

et al. 2018

J. Polym. Sci. Part A: Polym. Chem.

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Blended resins were prepared from the resorcinol-based PEEK-like oligomeric phthalonitrile resin (RES) and tetrakis(phenylethynyl)benzene (TPEB), a high char yield arylacetylene resin. Initial probing of curing properties using differential scanning calorimetry, indicated that TPEB and RES co-cure when heated. Characterization of thermal properties using thermogravimetric analysis indicated that a 1:1 TPEB-RES blend (by weight) exhibited a char yield of 80% which was 6% larger compared to pure RES (74%). According to FTIR characterization, the enhanced thermal properties of TPEB-RES were the result of increased crosslinking density. Rheological studies of TPEB, RES, and TPEB-RES blends indicated that blended systems exhibit similar processing characteristics as RES resin. For example, resins display ideal viscosities and relatively large processing windows when cured at 175 C. Alternatively, pure TPEB resin exhibits low viscosities when melted, which are not suitable for preparing composite materials. This study indicates that preparing TPEB-RES blends is an effect strategy for improving thermal performance of potential RES composites while still maintaining the required processability for fabrication of dense polymer composites.Additional supporting information may be found in the online version of this article.

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Formation and Stability of Metastable Tungsten Carbide Nanoparticles

Cited by 10 publications

References 24 publications

Nanoparticle Size Effects on Phase Stability for Molybdenum and Tungsten Carbides

Nanoparticle Size Effects on Phase Stability for Molybdenum and Tungsten Carbides

Synthesis, structure, and properties of polymer‐derived, metal‐reinforced boron carbide cermet composites

Oligomeric phthalonitriles and tetrakis(phenylethynyl)benzene blends with improved processing and thermal properties

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