Direct mechanical measurement of the tensile strength and elastic modulus of multiwalled carbon nanotubes

Demczyk, B. G.; Wang, Y.M; Cumings, John; Hetman, M; Han, Wei-Qiang; Zettl, A.; Ritchie, Robert O.

doi:10.1016/s0921-5093(01)01807-x

Cited by 996 publications

(443 citation statements)

References 29 publications

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“…Third, tension inversion leads to an indistinguishable configuration, and thus there must be a 180°period in the angular dependence (i.e., 2 is the lowest harmonics). Further, to quantify the activation barrier dependence, a number of saddle-point search computations were performed for the nearly equal diameter tubes (10,0), (8,2), (7,4), and (6,6) of chirality ϭ 0°, 10.9°, 21.1°, and 30°respectively. For every tube we considered three generic bonds with two flip directions for each bond.…”

Section: Resultsmentioning

confidence: 99%

“…In experiment, refined loading techniques often based on atomic force microscopy and combined with electron microscopic imaging allowed one to measure the breaking-strain level and observe the overall failure patterns (6-10). The reported experimental values of breaking strain ranged within 2-19% because of variability of the samples and measurement conditions (6)(7)(8). In theory, bond rotation [that is a concerted movement of two atoms, known in chemistry as Stone-Wales isomerization (SW) (11)] has been recognized as a key step in mechanical relaxation (12)(13)(14).…”

mentioning

confidence: 99%

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Symmetry-, time-, and temperature-dependent strength of carbon nanotubes

Dumitrică

Hua

Yakobson

2006

Proc. Natl. Acad. Sci. U.S.A.

241

203

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Although the strength of carbon nanotubes has been of great interest, their ideal value has remained elusive both experimentally and theoretically. Here, we present a comprehensive analysis of underlying atomic mechanisms and evaluate the yield strain for arbitrary nanotubes at realistic conditions. For this purpose, we combine detailed quantum mechanical computations of failure nucleation and transition-state barriers with the probabilistic approach of the rate theory. The numerical results are then summarized in a concise set of equations for the breaking strain. We reveal a competition between two alternative routes of brittle bond breaking and plastic relaxation, determine the domains of their dominance, and map the nanotube strength as a function of chiral symmetry, tensile test time, and temperature.mechanics ͉ plasticity ͉ isomerization ͉ rate theory T he highest strengths of solids are obtained from specimens of utmost uniformity and perfection. Even a single defect can cause drastic loss of strength. Thin solid filaments (whiskers) have long been viewed as material structures that can sustain the greatest mechanical tension (1, 2). Small cross sections permit little room for defects in their bulk, and the only heterogeneity is caused by inevitable presence of the surface and the interfacet edges. Discovery (3) of carbon nanotubes (CNTs) offered, at least in principle, the next level of perfection, when in a cylindrical network all atoms are equivalently tied to the neighbors, and no ''weak spot'' is apparent. This intrinsic uniformity, together with the known strength of carbon bonds, must lead to extreme resistance to mechanical tension, as has been anticipated all along (4, 5). On the other hand, establishing the quantitative level of breaking strain and identifying the details of atomic-scale rearrangements responsible for initial yield turned out to be elusive both experimentally and theoretically.In recent years, much progress has been made in elucidating the atomic mechanisms of CNT failure. In experiment, refined loading techniques often based on atomic force microscopy and combined with electron microscopic imaging allowed one to measure the breaking-strain level and observe the overall failure patterns (6-10). The reported experimental values of breaking strain ranged within 2-19% because of variability of the samples and measurement conditions (6-8). In theory, bond rotation [that is a concerted movement of two atoms, known in chemistry as Stone-Wales isomerization (SW) (11)] has been recognized as a key step in mechanical relaxation (12)(13)(14). It leads to the lowest energy defect, a cluster of two pentagons and heptagons, 5͞7͞ 7͞5. In the lattice of hexagons (the nanotube body) it represents a dislocation dipole, which explains its formation under high tension. This particular relaxation step is most favorable thermodynamically, but because of the high barrier of SW (15-17) it requires thermal activation. In contrast, another mechanism recently analyzed (18) needs no thermal activation but...

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Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

Symmetry-, time-, and temperature-dependent strength of carbon nanotubes

Dumitrică

Hua

Yakobson

2006

Proc. Natl. Acad. Sci. U.S.A.

241

203

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“…Indeed, computational simulations have given Young's moduli (E) in the 0.9-1.8 TPa range 1-5 and the first measurements performed on MWNTs grown by the arc-discharge method (AD) have confirmed these expectations. [6][7][8][9] The low defect concentration related to the growth of AD-MWNTs at high temperatures (presumably above 3000 o C), is at the origin of their high mechanical strength. 10,11 This high strength could qualify AD-MWNTs as excellent reinforcement agents with relatively high aspect ratio (100-200) in composite materials.…”

Section: Introductionmentioning

confidence: 99%

Reinforcement of CVD grown multi-walled carbon nanotubes by high temperature annealing

et al. 2013

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We report on the increase of the Young's modulus (E) of chemical vapor deposition (CVD) grown multi-walled carbon nanotubes (MWNTs) upon high temperature heat treatment. The post heat-treatment at 2200–2800ºC in a controlled atmosphere results in a considerable improvement of the microstructure, chemical stability and electro-physical properties of the nanotubes. The Young's modulus of MWNTs of different diameters was measured by the deflection of a single tube suspended across the hole of silicon nitride membrane and loaded by an atomic force microscope tip. Contrary to previous reports, a strong increase of E was feasible due to the improved growth conditions of pristine carbon nanotubes and to the improved heat treatment conditions. However, the elastic modulus of CVD grown MWNTs still shows strong diameter dependence resulting from the remaining structural inhomogeneities in large diameter nanotubes.

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“…[1][2][3] A vital prerequisite for the MWCNT-assisted structural reinforcement of Al is the uniform dispersion of individual MWCNTs within the Al matrix with intimate interfacial contacts. 4) However, bundled structure of chemically stable, pristine MWCNTs has been the main challenge to achieving the expected structural reinforcement.…”

Section: Introductionmentioning

confidence: 99%

Multi-Walled Carbon Nanotube-Aluminum Matrix Composites Prepared by Combination of Hetero-Agglomeration Method, Spark Plasma Sintering and Hot Extrusion

et al. 2011

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Multi-walled carbon nanotubes (MWCNTs) with outstanding mechanical properties are considered as an ultimate reinforcement for conventional metals such as aluminum (Al), though they require uniform dispersion and intimate contacts with the host metal matrix. However, bundled structure of chemically stable, pristine MWCNTs has been the main challenge to achieving the expected structural reinforcement. In addition, the sole contribution of MWCNTs in strengthening the metal matrix has not been recognized yet, due to the concurrent strengthening mechanisms such as metal's work hardening, grain refinement, etc. Here, we prepared MWCNT-Al matrix composite powders with uniform MWCNT dispersion by using hetero-agglomeration principle, and fabricated fully dense 1.0 vol% MWCNT-Al matrix composite bulk by using spark plasma sintering (SPS) and a subsequent hot extrusion process, with a 40% improved tensile strength and an elongation to failure of 27.3% similar to that of cast pure Al. During the SPS process, the nanoscale surface defects of MWCNTs were infiltrated by momentarily formed liquid Al and an intimate Al 4 C 3 -free interface was formed between MWCNTs and bare Al matrix. After the hot extrusion process, straight MWCNTs aligned in the extrusion axis found intimate contacts with the dynamically recovered, crack-free Al matrix. Our study suggests that the tensile improvement realized in our extruded/SPSed composites is directly originated from an effective load transfer at the MWCNT/Al interface, because no evidence of Al work hardening or the formation of interfacial Al 4 C 3 crystals was detected.

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Direct mechanical measurement of the tensile strength and elastic modulus of multiwalled carbon nanotubes

Cited by 996 publications

References 29 publications

Symmetry-, time-, and temperature-dependent strength of carbon nanotubes

Symmetry-, time-, and temperature-dependent strength of carbon nanotubes

Reinforcement of CVD grown multi-walled carbon nanotubes by high temperature annealing

Multi-Walled Carbon Nanotube-Aluminum Matrix Composites Prepared by Combination of Hetero-Agglomeration Method, Spark Plasma Sintering and Hot Extrusion

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