Experimental investigation on mechanical properties of a fiber-reinforced silica aerogel composite
Experimental investigation on mechanical properties of a fiber-reinforced silica aerogel composite
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DOI：
10.1016/j.msea.2011.03.013
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发表时间：
2011-05
期刊：
影响因子：
6.4
通讯作者：
Xiaoguang Yang;Yantao Sun;D. Shi;Jinlong Liu
中科院分区：
文献类型：
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作者：
Xiaoguang Yang;Yantao Sun;D. Shi;Jinlong Liu
由于其极低的导热性，气凝胶已被用于隔热，但由于其低强度特性，其应用仅限于非承重结构。制备的纤维增强气凝胶具有更高的强度，但不牺牲其导热性。当纤维增强气凝胶作为承重绝缘材料时，必须研究两种行为：在评估温度下的压缩和应力松弛。首先对纤维增强气凝胶复合材料进行了室温和常温下的压缩试验，分析了温度对纤维增强气凝胶压缩性能的影响。应力松弛试验在室温和评估温度下以恒定0.1的应变进行1200s。实验结果表明，当温度从200℃升高到800℃时，应力松弛随温度升高而增大。前人的研究和对试样的扫描电镜（SEM）分析表明，25℃下试样的应力松弛和非弹性应变较小的可能原因有：(1)孔隙坍塌引起的裂纹和(2)界面脱落和滑动导致的纤维破坏两种时间依赖行为。而三种与时间相关的现象：(1)气凝胶纳米颗粒融合形成纳米颗粒团簇，(2)纤维应力松弛和(3)纤维因界面脱落和滑动而失效，可能是800°C下显著应力松弛行为的原因。
Aerogel has been used for thermal insulation because of its extremely low thermal conductivity, but the application has been restricted to non-loading-bearing structures by its low strength properties. Fiber-reinforced aerogel was prepared with higher strength but without sacrificing much of its thermal conductivity. While fiber-reinforced aerogel performs as load-bearing insulation, two behaviors must be investigated: compression and stress relaxation at evaluated temperature. At first, compression test was performed on a fiber-reinforced aerogel composite at both room and evaluated temperature, then the effects of temperature on compression properties of the fiber-reinforced aerogel were analyzed. Stress Relaxation Test was carried out at a constant strain of 0.1 for 1200s at both room and evaluated temperature. The experimental results show that the stress relaxations increase with the temperature rise from 200°C to 800°C. Previous research and Scanning Electron Microscope (SEM) analysis of specimens showed that two time-dependent behaviors: (1) cracks induced by collapse of the pores, and (2) fiber failures subject to interfaces that debond and slide, might be possible reasons for the stress relaxation and the small inelastic strain of specimen tested at 25°C. While three time dependent phenomena: (1) fusing of aerogel nanoparticles to form nanoparticle clusters, (2) fiber stress relaxation and (3) fiber failures subject to interfaces that debond and slide, would be possible reasons for the remarkable stress relaxation behavior at 800°C.