Compression and deformation mechanisms of a fiber-reinforced SiO2 aerogel composite
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摘要: 根据热防护系统的特征载荷, 研究了气凝胶的室温、高温压缩和压缩蠕变性能。研究表明纤维增强SiO2气凝胶的压缩曲线可划分为三个阶段: 线性阶段、屈服阶段和密实化阶段。相比纯气凝胶, 该材料具有较高的强度、良好的断裂韧性。该材料存在明显的室温和高温蠕变行为。室温条件下240 h内的蠕变历程可划分为三个阶段, 在168 h以后蠕变变形量达到稳定状态, 基本不再继续增加。对比试样在试验前、热处理后和蠕变试验后的显微结构发现, 气凝胶基体的密实化是加热后试样收缩和影响气凝胶蠕变性能的主要因素。Abstract: Compression and creep tests were carried out at room and high temperatures under the characteristic load of thermal protection system. Results show that the compression curve of the aerogel composite can be divided into three stages: linear stage, yielding stage and densification stage. The composite performs higher strength and fracture strain comparing with pure SiO2 aerogel. There is obvious creep deformation at room and high temperatures. The room temperature creep history in 240 h can be divided into three stages, in the third of which (i.e. after 168 h) the creep strain does not increase. The microstructures of specimens before creep, after heated and after creep were compared. It is found that the densification of aerogel matrix is the main reason for the sample shrinkage, as well as the creep behavior.
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Keywords:
- SiO2 aerogel /
- high temperature compression /
- creep /
- microstructure /
- sample shrinkage
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