The fracture toughness of glassy carbons at elevated temperatures

Zhao, Jianfu; Bradt, R. C.; Walker, P.L.

doi:10.1016/0008-6223(85)90190-3

Cited by 45 publications

(28 citation statements)

References 14 publications

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“…Nonlinear least square fitting of the stiffnesses of our most pristine specimens ( ρ ≥ 37:5%) with Eq. (1), assuming a Poisson's ratio v = 0.17 48 and considering a correction function to account for the structure's face holes ( Supplementary Note 4), estimated a constituent material stiffness (E s ) of 62 GPa. This agrees remarkably well with the literature utilized upper limit in Fig.…”

Section: Discussionmentioning

confidence: 99%

Plate-nanolattices at the theoretical limit of stiffness and strength

et al. 2020

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Though beam-based lattices have dominated mechanical metamaterials for the past two decades, low structural efficiency limits their performance to fractions of the Hashin-Shtrikman and Suquet upper bounds, i.e. the theoretical stiffness and strength limits of any isotropic cellular topology, respectively. While plate-based designs are predicted to reach the upper bounds, experimental verification has remained elusive due to significant manufacturing challenges. Here, we present a new class of nanolattices, constructed from closedcell plate-architectures. Carbon plate-nanolattices are fabricated via two-photon lithography and pyrolysis and shown to reach the Hashin-Shtrikman and Suquet upper bounds, via in situ mechanical compression, nano-computed tomography and micro-Raman spectroscopy. Demonstrating specific strengths surpassing those of bulk diamond and average performance improvements up to 639% over the best beam-nanolattices, this study provides detailed experimental evidence of plate architectures as a superior mechanical metamaterial topology.

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Section: Discussionmentioning

confidence: 99%

Plate-nanolattices at the theoretical limit of stiffness and strength

et al. 2020

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“…The toughness is also an important property to evaluate the reliability of a structure, especially for a brittle material. The data in the literature confirmed the brittleness but had shown quite large scattering of the toughness in the range 0.58 -1.18 MPa•m 1/2 for GC treated at 2000˚C [6] [9].…”

Section: Introductionmentioning

confidence: 65%

Mechanical Properties for Reliability Analysis of Structures in Glassy Carbon

Garion¹

2014

WJM

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Despite its good physical properties, the glassy carbon material is not widely used, especially for structural applications. Nevertheless, its transparency to particles and temperature resistance are interesting properties for the applications to vacuum chambers and components in high energy physics. For example, it has been proposed for fast shutter valve in particle accelerator [1] [2]. The mechanical properties have to be carefully determined to assess the reliability of structures in such a material. In this paper, mechanical tests have been carried out to determine the elastic parameters, the strength and toughness on commercial grades. A statistical approach, based on the Weibull's distribution, is used to characterize the material both in tension and compression. The results are compared to the literature and the difference of properties for these two loading cases is shown. Based on a Finite Element analysis, a statistical approach is applied to define the reliability of a structural component in glassy carbon. In this paper, the determination of the mechanical properties of glassy carbon allows the analysis of reliability of structures in glassy carbon.

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“…Glassy carbon Young's modulus ( E ) and thermal expansion coefficient (α) as a function of temperature. E and α were extracted from Zhao et al and Werner et al, respectively. The thermal expansion coefficient was considered to be the same for the temperatures below 200°C [Color figure can be viewed at wileyonlinelibrary.com]…”

Section: Methodsmentioning

confidence: 99%

On the nonlinear behavior of Young's modulus of carbon‐bonded alumina at high temperatures

et al. 2018

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The origin of the nonlinear behavior of the Young's modulus (E) of carbon‐bonded alumina at high temperatures was addressed, based on the microstructural changes observed during processing and their thermo‐mechanical properties. Impulse excitation technique, thermogravimetric analysis, porosity measurement, and scanning electron microscopy were conducted in order to highlight and explain the E behavior. The finite element model of a virtual microstructure was simulated and the results attained are in good agreement with the experimental data. The tests revealed that the Young's modulus of a cured sample heated from room temperature up to 500°C was governed by the release of volatiles. Above this temperature, the thermal expansion mismatch among alumina, graphite, and the carbon matrix is dominant resulting in an increase in the effective Young's modulus. During cooling, crack networks and gaps between alumina particles and the carbon matrix were developed. The former were induced by volatile release and by the graphite's highly anisotropic thermal expansion. The latter was derived by the thermal expansion mismatch between the alumina and the carbon matrix. The closure of the gaps and cracks governed the expansion behavior during the second heating cycle and a nonlinear effective Young's modulus increase as a function of temperature was observed.

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The fracture toughness of glassy carbons at elevated temperatures

Cited by 45 publications

References 14 publications

Plate-nanolattices at the theoretical limit of stiffness and strength

Plate-nanolattices at the theoretical limit of stiffness and strength

Mechanical Properties for Reliability Analysis of Structures in Glassy Carbon

On the nonlinear behavior of Young's modulus of carbon‐bonded alumina at high temperatures

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