Julie has taught high school Zoology, Biology, Physical Science and Chem Tech. She has a Bachelor of Science in Biology and a Master of Education.
What is Aerogel?
Holding a world record is a lofty goal. Whether that is the longest moustache (14 feet), or the fastest run mile (less than four minutes), it must feel like an accomplishment to be the best at something.
It's not just people who hold world records. Aerogel, as it turns out, holds the world record for numerous feats including the best insulator and the lowest speed of sound. But wait, what is aerogel?
Aerogel is a class of dry, porous, solid gels. While you typically imagine gels as goopy, jelly-like liquids, aerogel is a solid that is made from gels. Due to its cloudy appearance, it has earned the nickname 'frozen smoke', even though it is neither.
Because of its unique properties, aerogel has countless uses from space suits to insulating buildings. As more types of aerogels are created, the list of future uses is long and diverse.
Let's explore the structure and composition of aerogels so we can understand their unique physical properties.
Structure and Composition
'Aerogel' is a word used to describe a group of materials that share certain characteristics. These materials do not necessarily share the same chemical composition, although most aerogels are made from silica, which is another name for silicone dioxide.
While they do have a solid framework, most aerogel is around 99% air. You can see how it gets its name, as 'aero' is Greek for 'air' and it's made from gel. Put the two together and viola, you have aerogel.
Because of its structure, it is lightweight and not dense. In fact, scientists have created an aerogel that is only two times the density of air.
Aerogels are created through a series of steps termed sol-gel processing, which begins by mixing chemicals together to create a gel and then carefully drying the gel out, which is often achieved by applying heat. What's left behind is an internal, cross-linked skeleton of support.
While most aerogels are made from silica, scientists have created aerogels out of other materials like carbon, gold, and even plant cellulose.
Let's check out some facts about aerogel, beginning with some of its world record-breaking physical properties.
In 2017 it was announced that scientists created the least dense 3D printed material by using a 3D printer to make a grapheme, a type of carbon aerogel so light it can sit atop a flower petal.
Aerogel also holds the world record for 'best insulator'. This physical property is due to all of the air within aerogel. The trapped air insulates, keeping materials hot or cold, depending upon the temperature of the air inside the aerogel. For example, an aerogel tile that is less than an inch thick insulates as well as three inches of Styrofoam or 15 windowpanes of glass.
Aerogel holds the record for 'slowest speed of sound', as it is excellent at slowing down sound waves. For example, aerogel absorbs sound waves to a speed of 100 m/s, compared to air, which slows sound waves to 332 m/s. Aerogel is better at sound proofing than much denser materials like polyurethane foam.
Due to the internal framework, aerogels are strong compared to their densities and weight. Many can hold objects that are thousands of times heavier than they are.
Aerogel has countless uses. One of the most interesting might be from NASA, who wanted to study comet dust, so they utilized aerogel as a means to capture it. As you might imagine, catching comet dust is challenging. The dust is traveling fast, and slowing it down to capture it causes damage to the dust. But when the comet dust hits the aerogel, it is able to slow it down gradually, which allows it to be captured without changing its composition.
Aerogel is a class of dry, solid, porous materials made from gel. It is created through a process called sol-gel processing, where a gel is heated and dried, and the remaining solid structural support remains but the liquid is gone.
Usually aerogels are made from silica, but they can also be made from carbon, metals and other materials. Over 99% of aerogel is air. Aerogels have unique properties including:
- Low density
- Strength (it can hold thousands of time its own weight)
- Slows sound waves considerably
- Excellent insulator
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