Tension–compression anisotropy of in-plane elastic modulus for pyrolytic carbon

Nanoscale elasticity of highly anisotropic pyrocarbons

“…Results on the commercial high textured PyC [9,7,11] show extremely low E 1 values, in the range [6:30 GPa]. This is from one to two orders of magnitude lower than our predicitions on RL and ReL PyCs.…”

“…The latter include results from tensile tests performed on low modulus carbon fibers coated by RL and ReL PyCs, as-prepared and after heat treatment at 1600° [10], as well as tensile (TT) and compressive tests (CT) [11], ultrasound phase spectroscopy (US) [7] and three point bending tests (TPB) [9] on a commercial high textured PyC. Existing results from nanoindentation [34,35,8,12] were not included because of serious questions raised in the literature regarding the ability of these methods to separate in-plane and out-of-plane properties [8,12].…”

“…Indeed, C 11 constants obtained using acoustic methods are in the range 40-50 GPa [6,7]; indentation moduli are around 10-30 GPa, i.e. lower or equal to the transverse values [8,12]; longitudinal moduli from tensile/compression tests show values ranging from around 20 GPa [11] as-prepared PyCs [10] and up to 400 GPa when heat treated at high temperature (2200°C) [10].…”

“…Nevertheless, a few studies report on the elastic properties of such PyCs as obtained by acoustic methods [6,7], micro and nano indentation [8,9] or uniaxial tension/compression tests [10,11]. High textured PyCs are isotropically transverse materials with a supposed high anisotropy of properties.…”

Effective stiffness and thermal expansion coefficients of unidirectional composites with fibers surrounded by cylindrically orthotropic matrix layers

“…We investigate 3 possible choices for PyC matrix material: isotropic, transversely isotropic with axis of symmetry in the direction of fiber and cylindrically orthotropic. Table 1 presents the considered material parameters: Matrix_1 was investigated in Avery and Herakovich (1986), the parameters for Matrix_2 and Matrix_3 are chosen based on the values for high-textured pyrolytic carbon reported in Gebert et al (2010) and Gross et al (2011). Fig.…”