Recently, according to Russian media reports, the Russian National Aerospace Corporation is developing new materials for use in the manufacture of launch vehicles, spacecraft, satellites and other spacecraft. At the same time, countries including the United States and the United Kingdom are also discussing the forming and processing technology of new aerospace materials and the precise manufacturing of complex parts of spacecraft and intelligent equipment technology. So why does aerospace engineering pay so much attention to material development?
The foundation of the spacecraft
Spacecraft are vehicles that operate in space in accordance with the laws of celestial mechanics and perform specific tasks such as exploration, development, and utilization of space and celestial bodies. They mainly include rockets, satellites, and spacecraft. They are the "pioneers" of mankind in opening up and expanding in the universe.
However, this "pioneer" is not appropriate. In order to break through the constraints of the earth's atmosphere, the spacecraft will generate friction with the atmosphere when flying at high speeds, and its heat can even reach more than 2000 degrees Celsius. When the spacecraft breaks out of the earth’s atmosphere, the ordeal will not stop there. In the space environment, ultraviolet radiation, particle radiation, thermal radiation, etc. will bring many challenges to the spacecraft. Even in a vacuum environment, it will be like a "cupping device". It also tests the endurance of the spacecraft’s skin.
In addition, there are major threats posed by space objects such as micro meteors in space and spacecraft debris. They are like stray bullets that test the "strength" of spacecraft, and all the above-mentioned tests faced by spacecraft are To be sustained by the materials of the spacecraft.
Materials are an important pillar of modern science and technology, social and economic development and national security. Many countries in the world have included materials technology in their national key technology research plans. The dependence of aerospace equipment on materials is particularly prominent. This is because materials are not only the actual bearers of the harsh space environment, but sometimes also undertake important tasks such as power supply, shielding, and heat dissipation.
However, the choice of spacecraft materials is not an easy task. On the one hand, because the spacecraft has a complex structure, including requirements for high temperature resistance, impact resistance, and even low temperature resistance, a comprehensive analysis must be carried out and based on the structure design of the spacecraft, After weighing various requirements and conditions, the suitable material is finally determined. On the other hand, because the existing material system is very large, new materials are constantly being developed.
Generally speaking, the material system of the spacecraft is very complicated, mainly including structural materials that realize the load-bearing of the spacecraft, functional materials that realize the requirements of temperature control and heat resistance, and fuel to promote the flight of the spacecraft.
Tough and thin structural materials
The structural material is based on the mechanical properties and is the material used to manufacture the force-bearing components. This material is like the bones of a spacecraft, the shaper of its shape.
However, the proportion of structural materials in spacecraft is very small. Taking the rocket as an example, the proportion of the structural material of the rocket shell in the whole is almost the same as the proportion of the egg shell in the whole egg. This is because on rockets, the fuel is "dead weight" and cannot be increased or decreased at will. Therefore, researchers will put their minds on the shell of the rocket and make the shell of the rocket thinner in order to reduce the weight of the rocket.
For every kilogram of the rocket's weight, it can increase its payload by one kilogram. An important function can be added to the carried satellites and spacecraft.
When the rocket reaches the first cosmic speed, it bears a very large force, which can reach about 7 times its own weight, which requires materials to withstand it. Not only that, when the rocket is flying, it also faces huge aerodynamic heat generated by friction with the atmosphere, and its engine also faces unimaginable heat energy.
In this case, the lighter the weight of the structural material, the better, the higher the heat-resistant temperature, the better, and a certain degree of formability is required. Although tungsten and other non-ferrous metals have better temperature resistance, their own density is very high, and at the same time they are very expensive and difficult to shape, which greatly increases the manufacturing cost.
Under various constraints, iron-based metal materials, that is, steel, have entered the field of vision of scientific researchers. Although the heat-resistant temperature of ordinary steel can only reach about 1,000 degrees Celsius, the use of nickel, cobalt, tungsten and other elements can effectively increase the temperature of the steel, even reaching about 1500 degrees Celsius, so it is named "superalloy". Simultaneously. This material is also relatively easy to shape, so it has always been the darling of spacecraft.
Later, researchers discovered titanium alloys. With the same strength, this material has lighter parts, so it has become the "sweet and sweet" in spacecraft structural materials. However, because the temperature resistance of titanium alloy is worse than that of high temperature alloy, it needs to be lined with high temperature resistant functional materials.
With the advancement of mankind's exploration of space and the development of materials science, composite materials have become a new force in spacecraft structural materials. For example, carbon-carbon, carbon-silica and other ceramic-based composite materials can not only withstand high temperatures of 2000 degrees Celsius, but also have very light weight.
In short, the rapid progress of materials and related technologies will further promote the development of aerospace technology, allowing mankind to see farther, clearer, and go farther and safer.
