Anisotropic Elastic and Acoustic Properties of Bulk Graphene Nanoplatelets Consolidated by Spark Plasma Sintering

Abstract

Elastic anisotropy and acoustic attenuation in bulk material consisting of consolidated graphene nanoplatelets are studied. The material was prepared by spark plasma sintering, and exhibits highly anisotropic microstructure with the graphene nanoplatelets oriented perpendicular to the spark plasma sintering compression axis. The complete tensor of elastic constants is obtained using a combination of two ultrasonic methods: the throughtransmission method and the resonant ultrasound spectroscopy. It is shown that the examined material exhibits very strong anisotropy both in the elasticity (the Young moduli in directions parallel to the graphene nanoplatelets and perpendicular to them dier by more than 20 times) and in the attenuation, where the dissipative eect of the internal friction in the graphene nanoplatelets combines with strong scattering losses due to the porosity. The results are compared with those obtained for ceramic-matrix/graphene nanoplatelet composites by the same ultrasonic methods.

Elastic properties of silicon nitride ceramics reinforced with graphene nanofillers

“…What's more, E of graphene for increased number of layers along the c-axis remains almost constant but as low as 50-60 GPa according to computational modelling [25]. Also for measurements in bulks of compressed expanded graphite in the direction perpendicular to the flakes E is 70 MPa [26], which is 13 times lower than E reported for the in-plane orientation, and for a plain GNPs consolidated by SPS [27], the E reported along x 1,2 38 GPa and x 3 2 GPa directions are also rather low [28].…”

Graphene reinforced metal and ceramic matrix composites: a review

“…Internal shear friction of the GNP composite was shown to be significantly higher in the out of plane direction. Koller et al [189] showed that the highly anisotropic elastic behaviour and attenuation of GNPs is intrinsic to their structure, by evaluating acoustic properties of a bulk GNP compact; it was observed that elastic coefficients differ by a factor of 20 in the basal and c-axis directions. This is in agreement with the results of Lahiri et al [181] where it was shown that GNPs had substantial damping capability in the c-axis direction due to the spring like van der Waals bonding between graphene layers.…”

High-TC Superconductivity Originating from Interlayer Coulomb Coupling in Gate-Charged Twisted Bilayer Graphene Moiré Superlattices

“…Consequently, theoretical results [7,[67][68][69] and insights from available data are used to establish ζ following the methodology described in Section 3.2.3. An ambient-pressure value of ζ = 3.50(1) Å is obtained for device M2, and from considerations of TBG under uniaxial pressure [3,70] with an elastic anisotropy approximating graphite [71], ζ = 3.42(1) Å is found for device D2 at a hydrostatic pressure of 1.33 GPa.…”

“…Since the C-C bonds of the in-plane hexagonal network are generally much stronger than the interlayer van der Waals bonds, it is reasonable to assume a strong anisotropy in elasticity. Assuming an elastic ratio similar to that of graphite [71], the strain induced from hydrostatic compression is strongly dominated by the transverse z component. From the results of calculations presented in [70], a uniaxial compressive strain of magnitude 2.19% is determined for P = 1.33 GPa.…”