【摘要】 采用低密度三维刚性结构作为增强体,利用Si-B-C陶瓷先驱体对纤维进行抗氧化防护,并在纤维骨架的孔隙中填充纳米隔热酚醛树脂,形成了一种抗氧化三维纤维增强酚醛气凝胶材料(三维结构热防护材料)。该材料密度从0.3 g/cm~3提升至0.7 g/cm~3,其弯曲强度从12 MPa提升至57 MPa,拉伸强度从10 MPa提升至46 MPa,压缩强度从2 MPa提升至18 MPa,比热容维持在1.07～1.1 J/(g·K),热导率从0.078 W/(m·K)提升至0.12 W/(m·K)。经15 min、2 000℃的电弧风洞烧蚀后,该材料后退量为10 mm。综合热力性能测试表明,该材料具有优异的力学强度和抗失效能力,而且纤维采用先进的抗氧化处理,在烧蚀过程中利用原位陶瓷化反应,提升了高温抗烧蚀能力,这种三维结构能够实现多种复杂构型近净尺寸成型,有效提升了防热材料的一体化制备、高效装配的任务适应能力。该类材料在载人航天、高超飞行器防热结构中具有广阔的应用前景。更多还原

【Abstract】 In this paper, a novel anti-oxidation 3 D fiber preform reinforced phenolic aerogel thermal protection system(3 DTPS) 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/cm~3 to 0.7 g/cm~3, 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.更多还原