Preparation and thermal insulation performance characterization of endothermic opacifier doped silica aerogel
Preparation and thermal insulation performance characterization of endothermic opacifier doped silica aerogel
复制标题
吸热遮光剂掺杂二氧化硅气凝胶的制备及隔热性能表征
DOI：
10.1016/j.ijthermalsci.2021.107431
复制
发表时间：
2022-04-01
影响因子：
4.5
通讯作者：
Xu, Hai-Bo
中科院分区：
文献类型：
--
作者：
Pang, Hao-Qiang;Zhang, Rui;Xu, Hai-Bo
掺杂经典遮光剂会抑制二氧化硅气凝胶在高温下的热辐射，但不能进一步提高其短期隔热性能。相变材料（PCM）在熔化时可以吸收热量，同时保持近乎恒定的温度，从而有效控制绝缘体内部的热量传递。因此，将经典遮光剂与相变材料相结合是解决二氧化硅气凝胶高温隔热问题的合理解决方案。本文制备了双尺寸的Al-Si@Al2O3（1-3μm/4-8μm），其壳层为Al2O3，可抵抗红外辐射，核为Al-Si合金，可在固-液相变过程中吸热。该吸热遮光剂(EO)的熔点(T-m)分别为846.25 K或846.75 K，潜热分别为277.9 J.g(-1)或318.2 J.g(-1)。随后，将EO掺杂到二氧化硅气凝胶中，制备了散布二氧化硅气凝胶的吸热遮光剂（EOSA），并测试了EOSA热表面（T-hot）在温差（Delta T）下的温度响应，以评估其隔热性能。结果表明，两种EOSA（1-22 wt%）在固-液相变过程中，在小AT（T-m & T-cold = 288 K）下的有效导热系数为0.02463-0.03066 W m(-1) K-1或0.02636-0.03154 W m(-1) K-1，这意味着短期隔热性能得到改善。纯二氧化硅气凝胶的隔热性能在小Delta T时隔热性能最好，在大Delta T时隔热性能最差，而EOSA在1-3μm时隔热性能较差。在大T下EO具有最好的隔热性能。
Doping classical opacifiers will restrain silica aerogel's thermal radiation at high-temperature but cannot further improve its short-term thermal insulation performance. The phase change material (PCM) could absorb heat while maintaining a nearly constant temperature when melting, thus effectively controlling the heat transferred inside insulators. So, combing the classical opacifiers and PCM was a reasonable solution to the thermal insulation of silica aerogels at high-temperature. In the paper, dual-sized Al-Si@Al2O3 (1-3 mu m/4-8 mu m) with a shell of Al2O3 against infrared radiation and a core of Al-Si alloy for heat absorption during a solid-liquid phase change was prepared. This endothermic opacifier (EO) presents the melting point (T-m) of 846.25 K or 846.75 K and latent heat of 277.9 J.g(-1) or 318.2 J.g(-1), respectively. Subsequently, the EO was doped into silica aerogel to prepare an endothermic opacifier interspersed with silica aemgel (EOSA) and the temperature response of the hot surface (T-hot) of the EOSA was tested at temperature differences (Delta T) to evaluate its thermal insulation performance. The results demonstrated that the effective thermal conductivity of the two EOSAs (1-22 wt%) was 0.02463-0.03066 W m(-1) K-1 or 0.02636-0.03154 W m(-1) K-1 at small AT ( T-m & T-cold = 288 K) during the solid-liquid phase change process, meaning that the short-term thermal insulation performance was improved. The thermal insulation performance of pure silica aerogel is the best at small Delta T but the worst at large Delta T, whereas the EOSA with 1-3 mu m. EO has the best thermal insulation performance at large T.