The appearance of magical materials
In the long river of human historical development, the birth of new materials can always stir up ripples and promote the progress of civilization. Today we are going to unveil a miraculous new material, aerogel, which has not only set 15 world records, but also has unimaginable performance characteristics: lighter than air, excellent thermal insulation, as if it is a "warm and insulating jacket" from the future.
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Schematic diagram of a piece of silica aerogel
Presentation of work scenes
Imagine that when the mainland's "Zhurong" Mars rover landed on Mars in 2021, it faced an extremely extreme environment, one moment to withstand the thousands of degrees Celsius generated by the engine, and the other time to adapt to the cold test of minus 130 °C. It turned out that the scientific researchers cleverly laid a large area of aerogel plates on the surface of the rover, which was like putting on a lightweight and warm "space suit" for the rover, so that it could work steadily in an environment of ice and fire.
Zhurong on Mars
In fact, aerogel is a solid material so dense that it can almost "float up", and is famous for its lightness like frozen smoke, solid air, or blue smoke. Its internal structure resembles that of a nano-sized porous sponge, except that these pores are filled with gas, which gives the aerogel its low density, high transparency, and excellent thermal insulation.
A brief introduction to the production process
The process of making aerogel is like magic. First we need a wet gel (similar to the jelly we loved to eat when we were children), and then through a technique called supercritical drying, all the solvents in the wet gel are extracted while keeping its shape unchanged, and the aerogel is as light as a feather. One of the most key technologies is to take advantage of the unique properties of supercritical fluids, under specific temperatures and pressures, the solvent and the solid backbone "peacefully separate" without destroying the original three-dimensional network structure of the gel.
From wet gel to aerogel
Thermal insulation principle
Aerogel is a great insulator, and it has three secret weapons. The first trick, the "zero convection effect", because the internal pore diameter of the aerogel is much smaller than the free path of air molecules, it is difficult for heat to be transferred through collisions, which greatly reduces thermal convection and heat conduction. The second trick, the "infinite thermal separator effect", the aerogel is densely covered with nano-level pores, although there are many but there is no "path", and the countless hole walls are like a heat shield, effectively blocking the transmission of thermal radiation. The third trick, the "infinite path effect", the heat zigzags forward in countless micropores, which is equivalent to embarking on a never-ending maze road, and the heat transfer is minimized.
There are three mechanisms of heat transfer
Wide range of applications
Today, the aerogel family has flourished, from the original silica aerogel to include oxide aerogel, carbide aerogel and other types. With their unique continuous three-dimensional network structure, they have a wide range of application prospects in thermal, mechanical, acoustic, optical, electrical, adsorption and other fields.
Excellent physicochemical properties of aerogel
Therefore, aerogel, the "super sponge" of the scientific community, with its incredible lightness and efficient thermal insulation, is quietly changing our lives, from aerospace technology to daily life, bringing more possibilities for human comfort and safety. Let's look forward to more exciting applications of aerogel in the future!
Applications of aerogel in various fields