Prediction of elastic properties of carbon fibers and CVI matrices

The mechanical properties of carbon materials are highly dependent upon nanostructure and orientation distribution of graphitic layer planes. A model of deformations based upon theory of elasticity for anisotropic solids is proposed. Then it is used for prediction of elastic modulus and Poisson coefficient from intrinsic elastic constants for particles and orientation distribution of graphitic planes. It was applied to carbon fibers and to carbon matrices produced via Chemical Vapor Deposition based techniques. The orientation distribution of graphitic planes was determined using the distribution of intensity of X-ray scattering I(ϕ). The predictions were compared to Young’s moduli measured on single fibers and matrices deposited on single fibers (microcomposites). The results underline the key role played by the modulus for shear between the graphitic layer planes. Influence of graphitic layer Poisson coefficient and Young’s modulus and nanostructure parameters is discussed.