AEROGEL : The future of thermal insulations
Most of us have heard or read somewhere about aerogel as the
lightest material on the planet. But do you know the other properties that it
exhibits? Let us know more about the properties and various applications of
aerogel and what makes it the lightest material on earth.
What are Aerogels?
Aerogels are extremely light translucent solid materials, which are
created by combining a polymer with a solvent to form a gel using sol-gel
method, and then removing the liquid from the gel and replacing it with air. These
are extremely porous and very low in density and are considered one of the
finest insulation materials. Out of all known solid
porous materials, aerogels are particularly known for their small pore size,
large specific surface area, and best optical transmission.
Aerogel contains a lot
of surface area due to its nanoscale sponge like structure. An Ice cube size
piece of aerogel has half the area of a football field. Yep you read it right.
This makes it good at absorbing lots of molecules, something which the
scientists have thought to exploit.
https://commons.wikimedia.org/wiki/File:BN_aerogel_on_hair.jpg
A
Brief History
In the 1930s, Samuel Stephens Kistler first produced silica aerogels by formulating the idea of replacing the liquid phase by a gas with only a slight shrinkage of the gel. He prepared aerogels from many other materials, including alumina, tungsten oxide, ferric oxide, tin oxide, cellulose, etc. Since the earlier methods and procedures were complex and time consuming, substantially the procedure was simplified by carrying out the sol-gel transition in a solvent, which was then removed at supercritical conditions. The first Cerenkov radiation detector based on silica aerogels was developed. Since then, the use of aerogels started in various domains aerogels have been used or considered for use in laser experiments, sensors, and thermal insulations.
Types of Aerogel:
There are mainly 3 types of aerogels, namely;
1. Silica aerogels (SBA) (Most Popular)
2. Polymer-based
aerogels
3.
Graphene Aerogel (world’s lightest
material)
Properties
that make Aerogels so Fascinating:
·
Porous: Aerogel is
extremely porous, the size of which falls in the nanometre range.
·
Light Weight: They have very low
density as they are extremely porous. This leads to very low weight of
aerogels.
·
Insulating: The
pores are so small that molecules of air cannot travel through, and this leads
to poor heat transfer throughout the material. Aerogel is an excellent thermal
insulator however, it is not the best material to work with.
·
High Surface Area: They
have very large surface area, which makes them susceptible to react faster than
other materials. These properties make aerogels to have potential applications
as adsorbents, catalysts, thermal insulation, and acoustic absorption materials
for environmental purposes.
Applications:
1. Insulation materials for micro
technology and medicine. With such extraordinary microporous structures it is comparatively
trivial to thermally insulate even the smallest electronic components from each
other. Another possible application is the shielding of heat sources inside
medical implants, which should not exceed a surface temperature of 37 degrees
in order to protect body tissue.
2. Aerogels are used for commercial purposes typically in pellet form or in a composite with other materials. Aerogels have been combined with batting to create insulating "blankets," as well as filled in between panes of glass to create translucent panels for day-lighting applications.
3.
|
This dust
collector for the spacecraft STARDUST was outfitted with 260 aerogel
panels. https://spinoff.nasa.gov/sites/default/files/2020-09/Aspen1web.jpg |
4. Aerogels can also be used in heavy metal removal, gas absorption, radioactive waste confinement, drug delivery , sensors , nuclear particle detection (Cherenkov), optics (light guides), Knudsen pump, electronic devices (solar cells, capacitors), catalysis and surface coatings (self-cleaning coatings, chemical resistant coating, etc.).
5. Aerogels
can also be used for developing novel anti-wetting, self-cleaning and thermal insulating
coatings on textiles.
Disadvantages: Well
nothing is perfect. Aerogels also have
some disadvantages, such as fragility, rigidity, dust formation, etc., which
limit their extensive applications. However, synthesizing fiber-reinforced
aerogel composites is one of the most effective methods to reduce the fragility
of the aerogels. Nonetheless, the fiber-reinforced aerogel composite has a
major problem that is dust-releasing from the fiber assemblies.
Future Perspectives:
The unique optical, thermal, acoustic, and
mechanical properties of aerogels originate from the combination of a solid
network and Nano sized pores filled with air. Drying of the gels is carried out
with supercritical or ambient pressure drying methods, depending upon the
commercial aerogel application. An extensive chemical modification provides a
new space for studying the property of aerogels. Ambient pressure drying
techniques will probably make industrial preparation much cheaper and will thus
make aerogels more competitive. The most important area for the application of
aerogels is in all kinds of thermal insulation, which will definitely grow in
the near future.
References :
1. https://www.hindawi.com/journals/jma/2014/127049/
2.
https://www.sciencedaily.com/releases/2020/08/200820102459.htm
3.
https://www.nasa.gov/topics/technology/features/aerogels.html
NOTE:- This blog is meant for Educational Purpose only. We do not own any Copyrights related to images and information , all the rights goes to their respective owners. The sole purpose of this blog is to Educate, Inspire, Empower and to create awareness in the viewers. The usage is non-commercial(Not For Profit) and we do not make any money from it.
Blog Credits: 1. Yash Chandak SY Comp 112003023
2. Priyanshu Raghuwanshi TY Meta 111911031
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