Preparation, mechanical properties and long-term ablation resistance of Cf/ SiBCN-ZrB2 composites

The Cf/SiBCN-ZrB2 composites were prepared by dipping and winding combined with reactive hot pressing. The flexural strength and fracture toughness reached 261 MPa and 11.96 MPa center dot m1/2, respectively, through continuous carbon fibers debonding, pulling and bridging mechanisms. Excellent mechanical properties ensured that the Cf/SiBCN-ZrB2 composites remained intact after exposure to a plasma flame with a heat flux of 9.37 MW/m2 for 300 s, with the mass and linear ablation rates of 1.78 mg/s, 1.01 mu m/s, respectively. The excellent ablation resistance was due to the formation of dense oxide layers separating the matrix from the plasma flame. The SiO2 formed in the low-temperature areas away from the center was the main ablation-resistant barrier, while the ZrO2/SiO2 double oxide layer formed in the high-temperature region at the center was the major ablation-resistant barrier.