Stress Graphitization

Inagaki, Michio

doi:10.1016/b978-0-12-407789-8.00005-3

Cited by 7 publications

(4 citation statements)

References 38 publications

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“…These diffraction peaks reported an average interlayer spacing ( d 002 ) of 0.33225 nm to 0.337 nm, as shown in Figure 2b. The d 002 which remained constant, was identified as a graphitic structure, which was similarly reported by other studies [31,32,33]. Accordingly, this indicated that there was no drastic change in the structure of the composite during the compression moulding process [34].…”

Section: Resultssupporting

confidence: 77%

Electrical Conductivity Performance of Predicted Modified Fibre Contact Model for Multi-Filler Polymer Composite

et al. 2019

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Polymer composites have been extensively fabricated given that they are well-fitted for a variety of applications, especially concerning their mechanical properties. However, inadequate outcomes, mainly regarding their electrical performance, have limited their significant potential. Hence, this study proposed the use of multiple fillers, with different geometries, in order to improve the electrical conductivity of a polymer composite. The fabricated composite was mixed, using the ball milling method, before being compressed by a hot press machine at 3 MPa for 10 min. The composite plate was then measured for both its in-plane and through-plane conductivities, which were 3.3 S/cm, and 0.79 S/cm, respectively. Furthermore, the experimental data were then verified using a predicted electrical conductivity model, known as a modified fibre contact model, which considered the manufacturing process, including the shear rate and flow rate. The study indicated that the predicted model had a significant trend and value, compared to the experimental model (0.65 S/cm for sample S1). The resultant fabricated composite materials were found to possess an excellent network formation, and good electrical conductivity for bipolar plate application, when applying compression pressure of 3 MPa for 10 min.

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Section: Resultssupporting

confidence: 77%

Electrical Conductivity Performance of Predicted Modified Fibre Contact Model for Multi-Filler Polymer Composite

et al. 2019

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“…The recrystallization of carbon material is strongly dependent on the nanostructure of the precursor material, and the nanostructures can be divided into two types, called soft (graphitizing) carbon and hard (non-graphitizing) carbon, based on TEM observations (Inagaki et al 2014). Hard carbon consists of small hollow particles with walls that comprise a few carbon sheets, while soft carbon already has distorted fringes of carbon sheets.…”

Section: Pressure Dependence Of Graphitizationmentioning

confidence: 99%

“…Such a difference in nanostructure results in the large differences in final crystal size and annealing temperature when graphite is synthesized from amorphous carbon in the laboratory (e.g., Inagaki 1996). The acceleration of graphitization occurs (even at 0.5 GPa) as a result of the collapse, under hydrostatic pressure, of the small hollow particles with walls (Inagaki et al 2014). This process is more marked in the hard carbon, resulting in the heterogeneous recrystallization of amorphous carbon to a graphitic carbon.…”

Section: Pressure Dependence Of Graphitizationmentioning

confidence: 99%

Pressure dependence of graphitization: implications for rapid recrystallization of carbonaceous material in a subduction zone

Nakamura

Yoshino

Satish-Kumar

2020

Contrib Mineral Petrol

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We report the results of kinetic experiments of graphitization at various pressures (0.5-8.0 GPa) and durations (1 s to 24 h) at 1200 °C. The natural carbonaceous material in sedimentary rocks from the Shimanto accretionary complex and the Hidaka metamorphic belt, Japan, underwent systematic changes in crystallinity and morphology with increasing pressure. To assess the pressure dependence of graphitization, we adopted three approaches to formulating the graphitization kinetics using a power law rate model, a Johnson-Mehl-Avrami-Kolmogorov model, and a superposition method. Activation volumes of − 21.7 ± 3.0 to − 45.7 ± 4.5 cm 3 mol −1 and − 0.7 ± 0.2 to − 16.8 ± 1.8 cm 3 mol −1 were obtained for pressures from 0.5 to 2.0 GPa and 2.0 to 8.0 GPa, respectively. Such large negative activation volumes might arise from structural modification and compression in the primary carbonaceous material. We applied the experimental data to the Arrhenius-type equation of graphitization, extrapolated to geological P-T-t conditions. Our model predicts that carbonaceous material undergoing metamorphism for ~ 10 Myr at pressures of 0.5-3.0 GPa will begin to crystallize at around 350-420 °C and transform fully to ordered graphite at around 450-600 °C, depending on the peak pressure. Thus, natural graphitization might proceed much more rapidly than previously estimated, owing to the large negative activation volumes for the reaction rate. This indicates that subducted carbonaceous materials will completely convert to fully ordered graphite by rapid recrystallization and metamorphic devolatilization before reaching sub-arc depths (< 100 km).

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“…For example, pure graphitization of amorphous carbon (a-C) requires a temperature higher than 3300 K, typically combined with high pressure. [25][26][27] The temperature of catalytic graphitization using transitional metals as catalysts lowers to around 1300 K, but find that Cu is not able to induce graphitization of solid carbon precursors. [28][29][30][31] The chemistry of different carbon precursors at a Cu surface could be similar, namely, as like a gas phase precursor, decomposition of the precursor, surface diffusion and nucleation, island growth, and island merger to generate a continuous graphene film.…”

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confidence: 99%

Hydrogen‐Enhanced Catalytic Conversion of Amorphous Carbon to Graphene for Achieving Superlubricity

Yang

et al. 2023

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The solid‐state conversion of amorphous carbon into graphene is extremely difficult, but it can be achieved in the friction experiments that induce macroscale superlubricity. However, the underlying conversion mechanisms remain elusive. Here, the friction experiments with Cu nanoparticles and (non‐hydrogen (H) or H) a‐C in vacuum, show the H‐induced conversion of mechanical to chemical wear, resulting in the a‐C's tribosoftening and nanofragmentating that produce hydrocarbon nanoclusters or molecules. It is such exactly hydrocarbon species that yield graphene at hydrogen‐rich a‐C friction interface, through reaction of them with Cu nanoparticles. In comparison, graphene isn't formed at Cu/non‐H a‐C friction interface. Atomistic simulations reveal the hydrogen‐enhanced tribochemical decomposition of a‐C and demonstrate the energetically favorable graphitization transformation of hydrocarbons on Cu substrates. The findings are of importance to achieve solid‐state transformation between different carbon allotropes and provide a good strategy to synthesize other graphitic encapsulated catalysts with doped elements.

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Stress Graphitization

Cited by 7 publications

References 38 publications

Electrical Conductivity Performance of Predicted Modified Fibre Contact Model for Multi-Filler Polymer Composite

Electrical Conductivity Performance of Predicted Modified Fibre Contact Model for Multi-Filler Polymer Composite

Pressure dependence of graphitization: implications for rapid recrystallization of carbonaceous material in a subduction zone

Hydrogen‐Enhanced Catalytic Conversion of Amorphous Carbon to Graphene for Achieving Superlubricity

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