高强度—中密度纳米孔树脂基防隔热复合材料的制备与性能

针对新一代航天器长时防隔热-高气动剪切的防热需求，以杂化酚醛树脂为基体、纤维布/纤维网胎逐层针刺结构为增强体，通过溶胶-凝胶工艺，制备出一种中密度-高强度-防隔热一体化的纳米孔树脂基复合材料(IPC-90)，系统研究了石英纤维(QF/IPC-90)和碳纤维(CF/IPC-90)对复合材料的微观结构、力学性能、静态隔热和烧蚀性能的影响，探讨了其在低-中-高温度下的烧蚀机制。结果表明：纤维布的引入使IPC-90具有优异的力学性能(拉伸曲强度>120 MPa，弯曲强度>90 MPa)；纳米孔基体和纤维网胎的引入使IPC-90在中密度(～0.95 g/cm³)下具有较低的热导率(室温热导率依次为0.089 W/(m·K)和0.120 W/(m·K))。在1 000℃静态隔热试验中，两种材料均展现了较好的热稳定性和抗氧化性，其等效热导率分别为0.142 W/(m·K)和0.186 W/(m·K)。在2 000℃以下氧-丙烷烧蚀试验中，QF/IPC-90和CF/IPC-90的烧蚀主要由基体热解、炭化收缩引起，其1 600℃下的线烧蚀率依次为0.0208 mm/s和...

Preparation and properties of high strength-medium density nanoporous resin-based ablation/insulation integrated composites

To meet the extreme thermal protection requirement of new-generation spacecrafts, nanoporous resin composites (IPC-90) with medium-density, high strength and excellent ablation/insulation properties had been prepared via a sol-gel polymerization using phenolic resin as nanoporous matrix and needled fiber fabric as the reinforcement. The effects of fiber type, namely quartz fiber (QF/IPC-90) and carbon fiber (CF/IPC-90) on the microstructure, mechanical properties, static thermal insulation, and ablation properties of the composites were systematically studied. The as-prepared IPC-90 with medium density of ~0.95 g/cm3 has excellent mechanical properties with tensile strength >120 MPa and bending strength >90 MPa. Due to the introduction of nanopore resin matrix and lightweight fiber felt, the resultant IPC-90 has relatively low room-temperature thermal conductivities (0.089 W/(m?K) for QF/IPC-90 and 0.120 W/(m?K) for CF/IPC-90), as well as low effective thermal conductivities at 1000℃. Furthermore, the possible ablation mechanisms under different temperatures were analyzed. It is found that both QF/IPC-90 and CF/IPC-90 have low linear ablation rates under the oxygen-propane ablation test below 2000℃, which are mainly caused by resin matrix pyrolysis and shrinkage. However, under the oxy-acetylene ablation test above 2000℃, the ablation of CF/IPC-90 is dominated by ultrahigh temperature carbonation-sublimation, while the severe ablation of CF/IPC-90 is caused by the melting of quartz fiber. Under the oxy-acetylene ablation of 4.2 MW/m2, the linear ablation rates of CF/IPC-90 and QF/IPC-90 are 0.073 mm/s and 0.186 mm/s, respectively, being similar to the conventional high-density phenolic composites.