PDF(Pubmed)
Abstract：
Hypersonic vehicles encounter hostile service environments of thermal/mechanical/chemical coupling, so thermal protection materials are crucial and essential. Ceramizable composites have recently attracted intensive interest due to their ability to provide large-area thermal protection for hypersonic vehicles. In this work, a novel ceramizable composite of quartz fiber/benzoxazine resin modified with fused SiO2 and h-BN was fabricated using a prepreg compression molding technique. The effects of the fused SiO2 and h-BN contents on the thermal, mechanical, and ablative properties of the ceramizable composite were systematically investigated. The ceramizable composite with an optimized amount of fused SiO2 and h-BN exhibited superb thermal stability, with a peak degradation temperature and residue yield at 1400 °C of 533.2 °C and 71.5%, respectively. Moreover, the modified ceramizable composite exhibited excellent load-bearing capacity with a flexural strength of 402.2 MPa and superior ablation resistance with a linear ablation rate of 0.0147 mm/s at a heat flux of 4.2 MW/m2, which was significantly better than the pristine quartz fiber/benzoxazine resin composite. In addition, possible ablation mechanisms were revealed based on the microstructure analysis, phase transformation, chemical bonding states, and the degree of graphitization of the ceramized products. The readily oxidized pyrolytic carbon (PyC) and the SiO2 with a relatively low melting point were converted in situ into refractory carbide. Thus, a robust thermal protective barrier with SiC as the skeleton and borosilicate glass as the matrix protected the composite from severe thermochemical erosion and thermomechanical denudation.
摘要：
高超音速飞行器遇到热/机械/化学耦合的恶劣服务环境，所以热防护材料是至关重要的。由于其能够为高超音速飞行器提供大面积的热保护，可陶瓷复合材料最近引起了人们的广泛关注。在这项工作中,使用预浸料压缩成型技术制备了一种新型的石英纤维/熔融SiO2和h-BN改性的苯并恶嗪树脂可陶瓷复合材料。熔融SiO2和h-BN含量对热的影响，机械,系统研究了陶瓷化复合材料的烧蚀性能。具有最佳量的熔融SiO2和h-BN的可陶瓷复合材料具有出色的热稳定性，在1400°C的峰值降解温度和残留物收率为533.2°C和71.5%，分别。此外，改性陶瓷复合材料具有优异的承载能力，弯曲强度为402.2MPa，在热通量为4.2MW/m2时具有优异的耐烧蚀性，线性烧蚀率为0.0147mm/s，明显优于原始石英纤维/苯并恶嗪树脂复合材料。此外,基于微观结构分析，揭示了可能的烧蚀机制，相变,化学键合状态，以及陶瓷化产品的石墨化程度。容易氧化的热解碳（PyC）和熔点较低的SiO2就地转化为耐火碳化物。因此，以SiC为骨架，硼硅酸盐玻璃为基体的坚固的热防护屏障保护了复合材料免受严重的热化学侵蚀和热机械剥蚀。
