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Abstract Damage development has been observed in situ within a 3-dimensional needle-punched carbon fiber reinforced carbon and silicon carbide (C/C-SiC) ceramic composite, as compressive loads were applied longitudinally, transversely and obliquely to its anisotropic structure. Laboratory X-ray computed tomographs were analyzed using digital volume correlation to measure the local strains. Cracks exist within the microstructure before the application of load, due to thermal strains, and their propagation is affected by the heterogeneous microstructure and the direction of loading. The punched carbon fiber needles are observed to restrict the propagation of damage. [ABSTRACT FROM AUTHOR]

Effects of SiC/HfC ratios on the ablation and mechanical properties of 3D C f /HfC–SiC composites by precursor impregnation and pyrolysis (PIP) process were investigated systematically. Both strength (flexural and compressive strength) and modulus increase as the SiC/HfC ratio are improved. The compact and stiff HfC-SiC matrix in addition to the carbon fiber and PyC interphase with less reaction damage accounts for the improved mechanical properties of C f /HfC-SiC with higher SiC/HfC ratios. Meanwhile, both weight loss and erosion depth of C f /HfC-SiC are improved with the increased SiC/HfC ratios. Therefore, in order to balance the ablation and mechanical properties, an appropriate SiC/HfC ratio should be considered. [ABSTRACT FROM AUTHOR]