Preparation and Characterization of Ultra-low Density Nano-aerogel Insulation Materials for Mars Rover
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摘要: 火星存在平均压力约600 Pa的CO2气体环境，以及最低温度约–123 ℃的温度环境，超轻质、高效隔热材料是火星车热控系统的关键性材料，保证内部电子元器件正常工作。气凝胶材料是目前大气环境下导热系数最低的固体材料，是火星车最佳的保温隔热材料方案。针对我国火星车应用需求，研制了密度小于30 kg/m3的低密度纳米气凝胶隔热材料，研究了低密度气凝胶的制备、复合材料的制备、超临界CO2干燥以及低密度气凝胶复合材料机加等制备过程，并表征了材料的热物理性能、真空挥发性以及热循环、热真空等空间热环境下的性能，表明低密度纳米气凝胶隔热材料在火星环境下具有良好的结构稳定性和隔热性能稳定性，可满足空间探测的应用需求。该材料具有良好的机加性能和优异的隔热性能，它的火星大气下室温导热系数为0.006 6 W/（m·K），实现了在我国火星车上的工程应用。Abstract: It is an atmospheric environment with an average pressure as 600 Pa of CO2 and a minimum temperature of -123 ℃ in Mars. Ultra-low quality and high efficient thermal insulation material is the key material for the thermal control system of Mars Rover to ensure the normal operation of electronic components. Aerogel is the solid material with the lowest thermal conductivity in the atmospheric environment. Therefore, it is the best insulation material choice for the thermal control of Mars Rover. To meet the need of Mars Rover, a low density nano-aerogel insulation material with density of less than 30 kg/m3 has been developed in this article. The preparation process of low density aerogel and composite materials, and the supercritical CO2 drying and ultra-low density aerogel composite’s being machined process are studied. The thermal physical properties, vacuum volatiles, the properties in the thermal cycling, thermal vacuum and other thermal environments are also characterized. The results show that the ultra-low density nano-aerogel insulation material has excellent structural and heat insulation stability in the Martian environment, which can meet the application requirement of space exploration. The material has good mechanical property and excellent thermal insulation property. The thermal conductivity of the low density aerogel composites is 0.0066 W/（m·K）at room temperature in Martian atmosphere which has been applied the Mars Rover in China.
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Key words:
- Mars /
- ultra-low density /
- aerogel /
- properties /
- insulation materials
Highlights● Silica aerogel composites with density as 30 kg/m3 were first prepared and applied in Mars Rover. ● The room temperature conductivity of low density aerogel composites was 0.006 6 W/（m·K）under the martial atmosphere. ● The properties and structure of low density aerogel composites were stable after the thermal cycling，thermal vacuum and other thermal environments experiments. ● The low density aerogel composite has been applied the Mars Rover in China. -
图 1 制备前驱体的半水解–半缩聚反应
Fig. 1 Semi-hydrolysis-condensation reaction to prepare silica precursor
图 3 低密度气凝胶氮气吸附–脱附曲线
Fig. 3 N2 adsorption and desorption isotherms of low density aerogel
图 6 密度为30 kg/m3的低密度气凝胶复合材料
Fig. 6 Low density aerogel composites with density as 30 kg/m3
图 10 不同气压和不同温度下的导热系数
Fig. 10 Thermal conductivity of low density aerogel at different pressure and temperature
表 1 真空条件下气凝胶复合材料挥发性能测试结果
Table 1 Volatility test results of aerogel composites under vacuum conditions
wt% 样品 总质量损失 可凝挥发物 吸湿率 S1 0.34 0.04 1.6 S2 0.30 0.05 1.4 S3 0.31 0.04 1.4 S4 0.34 0.04 0.6 平均值 0.322 5 0.042 5 1.25 
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表 2 热环境试验条件
Table 2 The condition of thermal environment experiment
项目 循环温度/（℃） 气氛 热循环 –145~+85 大气环境 热真空1 –145~+85 压力 ≤ 6.65 × 10–3 Pa 热真空2 –115~+85 1 400 Pa CO2气体
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表 3 不同环境试验条件下气凝胶复合材料的导热系数和尺寸收缩率
Table 3 Thermal conductivity and dimensional shrinkage under various environmental test conditions of aerogel composites
试验 1 400 Pa CO2气氛导热系数/
[W/（m·K）]尺寸收缩率/%
（长 × 宽 × 高）–40 ℃ 25 ℃ 前 后 前 后 热循环 0.003 3 0.003 3 0.007 0 0.006 9 0.2 × 0.1 × 0.7 热真空1 0.003 3 0.003 5 0.006 9 0.007 0 0.2 × 0.1 × 0 热真空2 0.003 5 0.003 5 0.007 0 0.007 0 0.03 × 0.7 × 0
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表 4 电离总剂量试验前后复合材料的性能
Table 4 The performance of aerogel composites before and after the total ionizing dose experiment
1 400 Pa CO2气氛导热系数/
[W/（m·K）]尺寸收缩率/%
（长 × 宽 × 高）–40 ℃ 25 ℃ 前 后 前 后 0.003 4 0.003 3 0.007 0 0.006 9 0.03 × 0.03 × 0.04
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