Aerogel
Aerogel covers a group of materials that were first used in space travel as far back as the 1960s. Today, it is being used in many industries. This is not a specific material or mineral with its own chemical formula. Instead, it refers to the objects that have a particular geometrical structure. The structure is a solid yet extremely porous foam that has high connectivity.
While it is technically a foam, it may take different forms and shapes. Most aerogel materials are made of silica but iron oxide, carbon, gold, copper, semiconductor nanostructures, and organic polymers. However, only a small part of the structure is solid material with about 99.8% of the structure containing only air, due to this unique space which makes it have an appearance that is almost ghostly, which is why it is also called frozen smoke.
Physical and Chemical Properties of Aerogel
The incredible lightness of Aerogel is one of its most significant and useful properties. It has a density of around 0.0011 to 0.5 g cm-3 and the average is about 0.020 g cm-3. What this means is that Aerogel is merely times heavier than air and it is made at a density of only three times. To get an idea of the lightness, if the David statue by Michelangelo was made from an aerogel, the weight would be equal to that of a bag of sugar. This material was the Guinness book of world records’ solid with the lowest density for many years before the metallic microlattice and subsequently, the aerographite.
Beyond that record, it is also the best insulator in the world, and some of its properties include;
- Thermal conductivity is low.
- Refractive index is low.
- Sound speed is low.
- The dielectric constant is low.
- Surface area when it comes to non-powder material is high.
- The mean of its free path to diffusion is low.
Creation of Aerogel
Simply put, Aerogel is made by drying gel in an environment with high temperature. Firstly, the gel is formed as a solution, and the supercritical drying is used to remove the liquid so that it can maintain its structure. Air is injected to replace the liquid component. The first production was by Samuel Stephen Kistler in 1931. In the 1980s, carbon aerogels were introduced.
Applications
Due to the diverse physical and chemical properties of this material, it has various applications. It has been used for insulating space suits as far back as the 1960s due to its ability to survive take-off conditions despite its look. It was also used to collect comet dust because it can capture small particles without affecting their physical properties. It is capable of capturing comet dust travelling at incredible speed without the dust melting. Recent developments which have improved its brittleness and fragility also means it will be open to more applications.