From the largest ships and planes to the smallest nano-robots, from the hardest materials to the softest materials ... mankind has been striving to create and break the best of all worlds. No, in 20 13, after the record of "the world's lightest substance" was broken by scientists in China, in 20 15, China once again set a new record, producing 0.12mg of the lightest substance per cubic centimeter. So, what are the functions of these ultra-light materials?
Curing smoke
The lightest material in the world is called aerogel. Aerogels are not really new. As early as 193 1, people made it with silicon dioxide. Aerogels have many small holes inside, which are filled with air, so they are light. In order to describe its lightness, people also gave it a nickname-solidified smoke.
In 20 1 1 year, aerogels made of nickel by American scientists became the lightest material in the world at that time. In a vacuum, this 1 cm3 aerogel weighs only 0.9 mg, which is lighter than air.
However, as the lightest material in the world, its record was not kept long before it was broken. In 20 12, several scientists in Britain and Germany developed the lightest aerogel in the world, and they also gave this aerogel a cool name called "flying graphite". 1 cm3 of "flying graphite" weighs only 0.18mg. Although it looks like a black opaque sponge, the sponge is much heavier than it. In terms of volume, "flying graphite" is almost composed of 99.99% air.
Ultra-light "carbon sponge"
The development of science and technology changes with each passing day. In the list of the lightest materials in the world, "flying graphite" sits at the first place, and as a result, its ass is squeezed down by another new type of aerogel before it gets hot. 20/kloc-in March, 2003, a research team from Zhejiang University in China prepared an ultra-light aerogel named "carbon sponge" from carbon nanotubes and graphene. How light is it? In vacuum, the weight of 1 cm3 carbon sponge is only 0.16mg, while the weight of ordinary air with the same volume is about 7 times that of helium with the same volume.
Carbon sponge is so light, how is it made?
Under the electron microscope, we can see that there are a lot of carbon nanotubes and graphene in the carbon sponge, and it is these two substances that support countless pores. Just like large stadiums, steel bars are used as support first, and then high-strength membranes are used as walls. Carbon sponge uses carbon nanotubes as a scaffold and graphene as a wall.
In the past, although scientists could prepare aerogels, it was difficult to produce them on a large scale because of the process. Now, the new technology invented by China can produce carbon sponge on a large scale.
Fiber aerogel
Scientists have not stopped pursuing the lightest materials. 20 15 The nanofiber research team led by Academician Yu and Professor Ding Bin of Donghua University in China has made new achievements in the research of ultra-light fiber materials. They developed an ultra-light and super-elastic fiber aerogel using ordinary fiber membrane materials. The domestic measurement certification results show that the solid density of this fiber aerogel is only 0. 12 mg per cubic centimeter. This is 0.04 mg lighter per cubic centimeter than the carbon sponge previously developed in China.
What can the lightest material be used for?
First, remove oil pollution
Aerogels use different materials, and their uses will be different. The carbon sponge aerogels developed by Zhejiang University not only made a breakthrough in preparation methods, but also showed superior properties.
Carbon sponge has good elasticity and can be restored to its original state after being compressed by 80%. It has ultra-fast and ultra-high adsorption capacity for oil, and is the material with the strongest oil absorption capacity at present. The current oil-absorbing products can only absorb about 10 times of their own weight, while the oil-absorbing capacity of carbon sponge is 250 times of their own weight, up to 900 times. Miraculously, the carbon sponge only absorbs oil and does not absorb water. In addition, it absorbs oil very quickly: every gram of carbon sponge can absorb 68.8 grams of oil per second. Having said that, many people think of the place where carbon sponge can be used, that is, cleaning up oil pollution at sea. When the sea surface is polluted by oil, when carbon sponges are scattered on the sea surface, they will continuously suck the surrounding oil spill into the body quickly.
Second, the adsorption of interstellar dust
Dealing with oil pollution is only one purpose of carbon sponge. As early as 1999, NASA used aerogels to adsorb interstellar dust.
Aerogel sample collector is installed on Stardust, which is mainly used to adsorb comet dust and interstellar dust.
When the "Stardust" probe passes through the comet dust, the velocity of the comet dust is very fast, about 6. 1 km/s, which is almost nine times the initial velocity of a rifle bullet. If these dust particles are collected by conventional methods, the shape and chemical structure of comet dust will change due to the excessive impact velocity, and some will even vaporize completely.
In order not to destroy them during collection, the aerogel sample collector is made of silicon-based solid material, with a porous structure like sponge inside, and 99.8% of the space is filled with vacuum. When dust particles hit aerogel, the process of slowing down and finally stopping is like an airplane taxiing and braking on a runway.
Third, thermal insulation and sound insulation.
Aerogel can also be an excellent thermal insulation (insulation) and sound insulation material because of its inherent characteristics.
Aerogel is not only the most ideal heat insulation material, but also a good sound absorption material. For example, this kind of fiber aerogel developed by China 20 15 can effectively absorb sound in the broadband of 100-6300Hz.
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