Aerogel is a solid material formed by replacing liquid in a gel with air. It is one of the lightest and lowest-density solids on Earth; 99.8% of its structure is filled with air. It is also known as “frozen smoke” or “blue smoke” because it resembles smoke. This material, which resembles frozen smoke, is almost as light as air itself and weighs only 1.74 grams. It is so light that even soap bubbles can easily carry it.
Aerogel, Withstand extreme temperatures from -273 degrees Celsius to 650 degrees Celsius The heat protection it provides is unmatched by other materials. However, even light pressure from a finger can shatter the aerogel into thousands of pieces, turning it into dust.
Another remarkable feature is that these powders become 100% hydrophobic and waterproof when applied to the body or other surface. This enables the production of non-fragile, foam-like aerogel composites that can be used in applications requiring protection in extreme conditions.
Aerogelscan be produced in a variety of ways. Since it is 99% air, the sound an aerogel makes is also quite interesting. It produces a metallic sound, like an empty can falling onto a steel surface; this sound is quite different from what most people expect.
Aerogel was first used in 1931 Steven Kistler It was obtained by using silica gel. The most striking features of aerogels are their extreme lightness and superior insulation capacity. Thanks to these qualities, they have been used in many areas and had 15 Guinness World Records in 2011. So why is it so difficult to burn or freeze it? The secrets in the structure of aerogel have long been a matter of curiosity in the scientific world.
Physical Properties of Aerogel
Aerogelsresembles a sponge with its structure containing millions of small pores on its surface. This material, which is 99.8% filled with air, is known as an extremely effective insulator. It shows much superior performance compared to foams and other insulation materials. It provides such good insulation that it can even insulate a flame given by a direct oxygen source. It has an insulation capacity 39 times higher than the most advanced fiberglass insulation material. Thanks to the Knudsen effect, it becomes even more insulating than the air inside.
Compared to glass, aerogel has a 1000% lower density and a porous structure. The material has pores that are billionths of a millimeter in size and these pores cover the inside of the aerogel like a network. The pores are surrounded by another material. Aerogels are translucent and can appear in blue tones, especially those based on silica gel, thanks to Rayleigh scattering.
These solid materials can carry large weights due to their rigid structure, but they are also brittle. Although they can carry thousands of times their own weight, they can shatter with a small impact. Due to their hydrophilic structure, they love water and have hygroscopic properties, so they feel dry when touched. However, with special treatments, this brittleness can be reduced and they can be made to repel water (hydrophobic).
Aerogel Production Process
Aerogel production consists of three basic stages: Turning the raw material into gel,
Strengthening the bonds by adding gas to replace air in the liquids in the gel, and
Drying to completely remove the liquid. The aerogel that emerges at the end of this process has a very light and durable structure.
The market size of aerogel products has grown significantly, from $25 million in 2004 to $500 million in 2013. This material, which is preferred in various fields such as insulation, scientific research, medicine, aviation, cosmetics and NASA’s space studies, also resists extreme hot and cold conditions.
Steven Kistler has succeeded in producing aerogels with metal oxides such as aluminum, chromium and tin oxides, as well as silica gel. In the late 1980s, carbon-based aerogels began to be produced. The fact that this unique material is largely composed of air, its lightness and superior durability have made it indispensable in many sectors.
Aerogel Types
After the initial discovery of aerogel, various types have been produced using different raw materials. Some of the aerogel types produced to date are: silica aerogels, carbon aerogels, organic-based aerogels, cellulose aerogels and many more composite or micro/nano-sized aerogel types have been developed.
Samuel Steven Kistler and the First Production of Aerogel
Kistler, the inventor of aerogel, first worked on silica-based aerogels. In the first production process, the drying method under atmospheric conditions was used, but due to the problems caused by the vapors that emerged in this process, Kistler developed the supercritical drying technique. This method created a major revolution in the drying of aerogels, allowing the material to maintain its structural integrity.
Areas of Use and Commercial Beginning of Aerogel
Kistler later left his university position and started a company where he commercialized aerogel production. In 1940, aerogel began to be used as an additive in products such as cosmetics and toothpaste. In the 1990s, the chemical and physical properties of these materials were further improved with the synthesis of carbon aerogels, which expanded their areas of use. In a study conducted in the USA in 2011, nickel-based aerogel was recorded as the lightest material ever produced.
Aerogel Production and Boron Waste in Turkey
In our country, aerogel production is also carried out by evaluating boron waste. While it is known that 75% of the world’s boron reserves are located in Turkey, 600,000 tons of waste is generated annually during the processing of these reserves. While some of this waste is used to obtain boron, some of it is turned into gel and evaluated in aerogel production. Thus, it is aimed for these wastes to contribute to the economy.
In Which Areas Is Aerogel Used?
Aerogels have excellent insulation properties thanks to their porous structure. The large amount of air voids they contain make this material very efficient in terms of heat, sound and electrical insulation. Their lightness is an additional advantage. These features make them an indispensable material in many different industrial and scientific fields.
Use in Space and Aviation Fields
One of the first notable uses of aerogels is space technology. NASA first used aerogel in the Mars Pathfinder mission in 1997. Since then, aerogel has continued to be used as an insulator in spacecraft. Thanks to its lightness and superior insulation properties, it plays an important role in space exploration.
Industrial and Structural Use
Aerogel’s insulation properties are also widely used in industrial and structural applications. For example, it is preferred as an insulator in oil pipelines to increase energy efficiency. Similarly, aerogel-based materials are used in the construction sector to provide thermal insulation in buildings. One of the modern applications of aerogel is known as aerogel windows. This technology provides excellent insulation by placing aerogel between two glass layers. It offers lighter and more effective insulation compared to traditional triple-layer glass windows.
Optical and Electronic Applications
Aerogels are also used in optical applications and electronic devices. Aerogels can be used to improve the performance of optical devices and to regulate their light transmission properties, providing innovative solutions in this area.
Academic and Scientific Development of Aerogel
With the popularization of aerogel, it has also attracted great interest in the scientific world. The first international aerogel symposium, held in Würzburg, Germany in 1985, is an indication of how important this material is in the scientific field. This symposium, which has been held every three years since then, brings together scientists working on the physical properties of aerogels, synthesis techniques and new areas of use.
Why Can’t Aerogel Be Burned or Freezed?
The reason why aerogel cannot be burned or frozen is due to its unique properties. Aerogel has an extremely porous structure consisting of 99% air. There are millions of tiny voids at the base of this structure, and these voids largely prevent heat transfer and energy transmission. Here are the reasons why aerogel is such an effective insulator:
Low Density: Since aerogel is mostly air, there is almost no solid material to transfer heat energy to. This makes the material resistant to heat, even at extremely high temperatures. Therefore, it is very difficult to burn even when in direct contact with a flame. Aerogel insulates the heat energy of the flame and therefore does not burn.
The Knudsen Effect: The pores of the aerogel are so small that gas molecules cannot move freely in these spaces. This further reduces its ability to conduct heat, making the material even more insulating than the surrounding air. Thus, even when faced with freezing temperatures, the aerogel retains its internal structure and does not freeze.
Low Thermal Conductivity: The air inside the aerogel is so limited that it cannot conduct heat. This feature makes the material resistant to both high-temperature burning and low-temperature freezing. Therefore, the aerogel can remain in extremely hot and cold conditions without losing its structure.
High Insulation Capacity: Aerogel provides dozens of times better insulation than even the most advanced insulation materials. The fact that it can even insulate fire from an oxygen source is related to the material’s superior thermal insulation. This feature also works against freezing temperatures; the internal temperature of the aerogel is maintained and freezing is prevented.
As a result, the inability of aerogel to burn or freeze is due to its extremely low density, excellent insulation capabilities and porous structure that prevents heat transfer. Thanks to these properties, it exhibits a unique resistance to extreme hot and cold conditions.
To join our WhatsApp group CLICK!
