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Did you know? Why is aerogel called "freezing smoke"?
Aerogel, this name may be quite unfamiliar to many people, but it is actually a wonderful material with surprising properties and uses. Aerogel is known as "frozen smoke" because it is thin and transparent in appearance and seems to blend into the air at the edges, giving people a fuzzy feeling like smoke. In fact, aerogel is a highly porous synthetic material made in a process that involves removing the liquid from the gel, leaving only the gas behind, which is one of the reasons it's called "frozen smoke."
Aerogels are made by extracting liquid from gels. This process can be achieved through supercritical drying or freeze-drying. The end result is a solid with extremely low density and almost zero thermal conductivity.
Aerogels are synthesized through a series of chemical reactions. The oldest record of aerogels can be traced back to 1931, when scientist Samuel Stephens Kistler conducted a presented the challenge of trying to replace the liquid inside the gel without causing it to shrink. The earliest aerogels were based on silica, but as technology advances, it is now possible to create aerogels composed of various chemicals.
Characteristics and properties of aerogels
Despite the word "gel" in the name, aerogel is actually a strong, rigid, dry material that does not possess any obvious gel properties. Its flexibility allows it to leave no marks when touched lightly, which may cause structural damage when greater force is applied. This characteristic means that although airgel breaks easily, its structure is actually very strong and capable of withstanding significant loads.
The tiny particles in aerogel form a nearly fractal three-dimensional porous structure, which can effectively reduce heat conduction and convection, making aerogel an excellent thermal insulation material.
The porosity of airgel enables it to exhibit superior thermal insulation properties. Because they contain large amounts of air in their structure, aerogels virtually eliminate heat losses from conduction and convection. However, aerogels perform poorly at radiation insulation because infrared radiation can penetrate these materials.
Aerogel manufacturing process
The process of making aerogels first involves mixing solid particles to form a "sol" that is then gelled. At this stage, the liquid reacts with the solid particles to form a gel. After the gel is completely formed, the next step is to remove the surrounding liquid, usually using supercritical drying or freeze-drying, which can effectively maintain the porous structure of the aerogel without damage.
During the supercritical drying process, the liquid is converted into a supercritical fluid, and then the internal liquid is quickly removed by reducing the pressure to avoid structural collapse.
During this process, aerogels can preserve their porosity and structural stability without directly undergoing a liquid-to-gas phase transition, making them a material with great potential. The popularity of this technology makes aerogels more and more widely used.
Applications of airgel
Due to its unique physical properties, aerogels are widely used in construction, aviation, electronics and other fields. In buildings, for example, it can be used as an efficient thermal insulation material to reduce energy consumption. In the aviation field, aerogels are used as lightweight insulation materials to protect spacecraft interiors from extreme temperatures.
In addition to traditional uses, recent research has also shown the potential of aerogels in environmental protection and water filtration technology, making it an important direction for future materials research.
With the advancement of science and technology, the characteristics and applications of aerogels will continue to be explored and expanded. We may be able to imagine that in the near future, aerogels can bring greater changes and progress to our lives.
So, in what other areas do you think aerogel can exert its unique value?
