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

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.