抗氧化三维纤维增强酚醛气凝胶的性能

In this paper, a novel anti-oxidation 3D fiber preform reinforced phenolic aerogel thermal protection system (3DTPS) was invented. Herein, a low density three-dimensional rigid preform was used as reinforcement, and the Si-B-C preceramic was used to protect the fibers from oxidation, nano-phenolic resin was impregnated into the pore of the preform to improve the capacity of heat shield. With the density increasing from 0.3 g/cm³ to 0.7 g/cm³, the flexural strength, the tensile strength, the compressive strength and the thermal conductivity increased from 12 MPa, 10 MPa, 2 MPa and 0.078 W/(m•K) to 57 MPa, 46 MPa, 18 MPa and 0.12 W/(m•K) respectively, while the specific heat capacity maintained at 1.07~1.1 J/(g•K). The ablation recession was 10 mm after tested in an arc wind tunnel at 2 000℃ for 15 min. The comprehensive thermos-mechanical properties revealed that such material can greatly improve the mechanical strength and its excellent anti-failure ability. Moreover, in-situ pyrolysis reaction was adopted in the ablation process to enhance the anti-oxidation ability at high temperature. Especially, this three-dimensional structure can realize near-net-size forming of various complex forms, which effectively enhanced the integration and assembly of the thermal protection material in task. This kind of material has broad application prospects in thermal protection structure of manned spacecrafts and hypersonic aircrafts.