Why does aerogel, a material lighter than air, shelter the "Zhurong" from wind and rain?


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Why does aerogel, a material lighter than air, shelter the "Zhurong" from wind and rain?

  • Categories:NEWS
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  • Time of issue:2022-09-26 14:36

Why does aerogel, a material lighter than air, shelter the "Zhurong" from wind and rain?

There is good news from the WeChat public account of China's lunar exploration project. The "Zhurong" rover has run on the surface of Mars for 100 Martian days and has traveled a total of 1,000 meters. Did you know that on the surface of the "Zhurong" solar panel, there is a solid that is lighter than smoke-aerogel, which has good thermal insulation performance and has made great contributions to the normal operation of the equipment on the vehicle. What is aerogel? Where is it great? Is it difficult to manufacture? The reporter of "Science and Technology Weekly" interviewed Professor Jin Zhong from the School of Chemistry and Chemical Engineering of Nanjing University to reveal the secret for you.

"The surface of China's 'Tianwen-1' Mars probe and 'Zhurong' Mars rover is made of aerogel materials to resist the temperature test of Mars' 'ice and fire'," Jin Zhong said. Said that the aerogel material is divided into two types: high temperature resistance and low temperature resistance, which respectively block the high temperature heat flow of up to 1200 ℃ generated by the landing engine of the probe, and protect the normal function of the landing platform; it can also ensure the normal environment of the Mars rover at -130 ℃. Work. Moreover, the extremely light weight of aerogel will not increase the load of "Tianwen No. 1". Take the aerogel material on the detector as an example. If it is made into a thin sheet, only 10 grams of this material is needed. It can cover a standard football field.

As the world's lightest density solid material, aerogel also has excellent properties such as light transmission, heat insulation, sound insulation, and insulation. It is also called "frozen smoke". "Despite the name, aerogel is actually a strong, dry, solid porous material, similar to an ultra-light sponge, so structurally strong that regular pressing won't leave marks or break it. , has an impressive load-bearing capacity, a 2-gram mass of aerogel can support a 2.5-kilogram brick."

The invention of aerogel originated from an accident. In 1931, the American Kistler was inspired by jelly to invent. The component of jelly is water. In order to ensure that the water does not flow out, the water molecules in the jelly grid are pulled by surface tension, and the surface tension is just at the critical point where the water cannot break free and can shake. So what happens if the liquid inside is pumped out and replaced with gas? According to this idea, American Kistler finally chose silica gel as the experimental object after numerous experiments. Using supercritical drying method, the liquid components in silica gel were removed, and the world's first real silicone was successfully made. Aerogel - Silica aerogel.

Subsequently, my country has also achieved a series of important achievements in the field of silica aerogel, some of which are even at the forefront of the world. Beginning in 2010, the first batch of domestic silica aerogel manufacturers have successfully developed the application market of industrial equipment pipeline energy saving, new energy vehicle safety protection, rail transit carriages and ship hull fire and heat insulation. In 2017, my country issued the national standard "Nanoporous Aerogel Composite Thermal Insulation Products"; in the same year, silica aerogel was included in the national recommended list of key energy-saving and low-carbon technologies. In 2019, the output of silica aerogel in my country was 78,200 cubic meters, and the market size of silica aerogel in my country in 2019 was about 1.123 billion yuan.

With the continuous in-depth research on silica aerogel, more and more understanding of its preparation process and properties has made the production process more convenient, and it has also made the large-scale manufacture and application of this type of new material possible. . "The first applications that people think of are in the chemical industry and environmental protection, using the large specific surface area and porosity of silica aerogel for catalyst support, gas filtration, or using this 'super sponge' to adsorb water All kinds of non-pollutants (such as oil pollution and heavy metal pollutants such as mercury, lead and cadmium, etc.) are excellent materials for dealing with ecological disasters." Jin Zhong explained that due to its porous structure and good biocompatibility, it can also be used as medicine. A delivery system that modulates the release rate of the drug by changing the properties of the silica aerogel.

In terms of space exploration, silica aerogel also has a variety of uses. This material is used on the Russian "Mir" space station and the US "Mars Pathfinder" probe. NASA's Stardust spacecraft takes it on an important mission in space -- collecting cometary particles. This is no easy task. Although comet dust is smaller than a grain of sand, its velocity is 6 times that of a rifle bullet. When it hits other matter at such a high speed, its own composition may be changed or even completely destroyed. evaporation. It's much easier now with silica aerogel, which is like an extremely soft baseball glove that gently dampens the speed of comet dust, making it slow after gliding a distance of 200 times its own length. Pause slowly and leave a spiky trail. Because the silica aerogel is almost transparent, scientists can easily find these cometary particles by following their trajectory.

"The most promising large-scale application areas for aerogels are thermal insulation, thermal insulation, and energy conservation." In construction, clothing, and industrial production, replacing traditional insulation materials with aerogels has great potential. The fine nano-network structure of silica aerogel effectively limits the heat conduction. It is the solid material with the lowest thermal conductivity at present, and it can block the infrared heat radiation of the ambient temperature, making it an ideal transparent thermal insulation material. It is used in solar energy utilization and construction. Energy saving has been applied, and it is expected to replace polyurethane foam as a new type of refrigerator insulation material.