Influence of high-speed gas flow on the tensile strength of 2.5D C/SiC composites

To investigate the influence of high-temperature gas environment on the structural strength of 2.5D C/SiC composites, tensile properties were analyzed using gas flow ablation tests on specimens subjected to different ablation durations (300 s and 600 s). The results show that the ablation rate of C/SiC increases slightly with ablation time. The linear and mass ablation rates were 0.453 μm/s and 0.682 mg/s for C/SiC ablated for 300 s and 0.492 μm/s and 0.744 mg/s for 600 s. The carbon fibers on the surface of the material were oxidized first, and cracks appeared in the silicon carbide matrix below the carbon fibers. Oxygen diffused through the cracks to the interior, and the carbon fibers inside the cracks were gradually oxidized. The carbon fibers became thinner and some areas appear spiky. Carbon fiber formed small pores after complete oxidation. The tensile strength and tensile modulus of 2.5D C/SiC composites were reduced.