Long-term oxidation resistance and reusability of a ceramizable composite for reusable large-area thermal protection of hypersonic aircraft

The rapid development of reusable hypersonic vehicles has put forward urgent demand for reusable large-area thermal protection materials. Herein, a novel ceramizable composite modified by Ti₃AlC₂ and B₄C was proposed, and its long-term oxidation resistance and reusability after isothermal cyclic high-temperature oxidation experiment at 1200°C for 30 min for 1–10 cycles were explored. The high-temperature bending strength after treated once reached 80.0 MPa, and it kept above 43 MPa and the structural integrity of the samples was good even after eight high-temperature oxidation treatments, demonstrating that the ceramizable composite possessed good application potential as reusable large-area thermal protection materials. The anti-oxidation mechanism was proposed based on microstructure evolution, element distribution, phase evolution, and thermodynamics analyses during the high-temperature oxidation cycles. Ti₃AlC₂ and B₄C underwent a series of ceramization reactions with O₂ and pyrolytic carbon (PyC), converting the ceramizable composite into a ceramized composite in-situ and playing the roles of oxygen consumption, self-healing, oxygen inhibition, carbon fixation, and heat absorption, by which carbon fibers and PyC were protected.