Temperature dependency of interlaminar shear strength of 2D-C/SiC composite

Interlaminar shear strength (ILSS) of a two-dimensional carbon fiber reinforced silicon carbide composite (2D-C/SiC) was investigated by compression test at elevated temperature in both air and vacuum. The fractured surfaces were observed by a scanning electron microscope. The results show that ILSS in air decreased when the material was tested at the temperatures lower than the preparation temperature (∼900 °C), among which the strength determined at 700 °C was the smallest. In contrary, ILSS in vacuum increased with increasing temperatures until 900 °C, and then decreased at 1200 °C. The different variation of ILSS with temperature is closely related to the damage mechanisms under the shear load. The main forms of the damages in vacuum, involve debonding of the interface between the fibers (or fiber bundles) and the matrix, matrix cracking and fiber pullout. However, the interaction between the oxidation of the constituents and above damages dominated damages accumulation and led to the contrary dependency of ILSS on the temperature in air.

► ILSS decreased with increasing temperature until 700 °C and then increase at higher temperature.
► ILSS determined in vacuum increased as rise of temperatures until 900 °C, then decreased at 1200 °C.
► In air, the oxidation of the fibers and the PyC interface plays important roles on the ILSS.