Anisotropic elastic moduli and internal friction of graphene nanoplatelets/silicon nitride composites

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

“…It can be seen that the Young modulus is the highest in the transversely isotropic plane (E 1 = 38.66 GPa) and the smallest in direction perpendicular to this plane (E 3 = 1.55 GPa). However, the Young moduli both in the in-plane and out-of-plane directions are incomparably smaller than those of graphite (E 1 = 1.03 TPa and E 3 = 36.1 GPa [18]), probably because of the porosity and the micromechanics of the GNPs in the studied material similar to the one suggested for GNPs embedded in a ceramic matrix in [10]. Nieto et al [11] reported on the Young moduli of the bulk GNPs measured by nanoindentation with signicantly dierent results (E 3 = 8.7 GPa and E 1 exhibiting a bi-modal distribution with the values E 1 = 10.3 GPa and E 1 = 15.2 GPa).…”

“…For example, for the silicon nitride/GNP composite reported in [10], the Hill averaging method (using E =324 GPa for pure silicon nitride and the above obtained results E 1 = 38.66 GPa and E 3 = 1.55 GPa for GNPs) gives E 1 = 273 GPa and E 3 = 168 GPa. However, the experimental results E 1 = 308 GPa and E 3 = 240 GPa for this CMC [10] are signicantly higher.…”

“…1 can be expected to exhibit transversal isotropy, i.e. rotational symmetry about the SPS compression axis, as usual for SPSed composites with spatially anisotropic arrangement of the individual constituents [10].…”

“…Various CMCs with highly oriented graphene-based laments were prepared by the spark plasma sintering (SPS) technique [68]. These composite materials exhibit, besides the expected improved fracture toughness, also signicant anisotropies in electric conductivity [6], thermal conductivity [7,9], elastic stiness and internal friction [10]. Recently, Nieto et al [11] reported on a bulk material consisting purely of the graphene nanoplatelets (GNPs) consolidated together by the SPS.…”

Microstructure and Mechanical Properties of Nanofiller Reinforced Tantalum-Niobium Carbide Formed by Spark Plasma Sintering

“…The functional properties include a high Young's modulus (0.5 -1 TPa) [10] and a high tensile strength (130 GPa) [11] which is why it is being considered for reinforcement in polymer, metallic, and ceramic composite matrices [12][13][14]. Graphene Nanoplatelets (GNP) are made up of multiple layers of graphene held together by weak van der Waals forces.…”