Transversal thermos-mechanical behaviour of continuous carbon fiber-reinforced ultra-high temperature ceramics

Coefficient of thermal expansion (CTE) and flexural strength (?f) of UHTCMCs based on ZrB2-matrix reinforced with 45 vol% of unidirectional continuous carbon fibers are investigated along the transverse direction (TD). By fitting the experimental CTE curves with the Schapery's model, it is shown how the model works if turbostratic microstructure of the pitch-derived carbon fibers is taken into account. The model suggests that fiber elastic modulus and Poisson's ratio are negligible along the TD and give Ef = 40 GPa, ?f = 0, respectively as effective values. In addition, we studied the effect of thermal cycling on the induced composite damage. By thermal cycling the sample for 5 times from RT up to 1300°C, both CTE and ?f did not undergo appreciable change, remaining constant at about 7.5·10-6 °C-1 and 65 MPa, respectively.