可重复使用高超声速飞行器面临着高温、潮湿、振动等复杂的服役环境,对热防护材料在极端环境下的耐久性提出了更高的要求。气凝胶材料作为最具潜力的热防护材料之一,具有十分优异的隔热性能,但复杂环境对其性能的影响仍需深入研究。以纤维增强SiO₂气凝胶为研究对象,研究了潮湿和振动环境对材料重复使用耐久性的影响。结果表明:在冷热循环和潮湿及振动影响下的冷热循环重复使用条件下,纤维增强SiO₂气凝胶材料隔热性能明显下降,并且潮湿及振动均会明显加速其恶化;在潮湿环境中重复使用会因材料中的水分子受热汽化而使其厚度增加;振动导致的材料结构疏松会使材料的纵向束缚减小,材料再次受热时产生的热膨胀会导致其厚度增加(层间分离)更为严重,同时气凝胶粉体从整体材料中脱落,引起质量减少,导致隔热性能下降更为严重。

Reusable hypersonic vehicles put forward higher requirements for the durability of thermal protection materials in extreme environment because they would always face with high temperature,humidity,vibration and other complex service environment.Aerogel material,as one of the most potential thermal protection materials,has excellent thermal insulation properties,but the effect of complex environment on its performance needs to be further studied yet.The influence of humidity and vibration environment on reuse durability of fiber reinforced SiO₂ aerogels was studied.The results showed that the thermal insulation properties of the material decreased significantly under the conditions of thermal-cooling cycle treatment with and without the effect of the humidity and vibration,and the additional conditions significantly accelerated the deterioration.The thickness of the material would increase due to the vaporization of inner water molecules when reused in humid environment.Due to the loose material structure caused by vibration,the longitudinal restraints of the materials would be reduced.The thermal expansion caused by heating will lead to more serious thickness increase on the material.At the same time,the aerogel powder would drop off from the matrix materials,resulting in the reduction of the quality and the more serious insulation performance.