The aerospace field has extremely stringent requirements for material properties. As a key material, silicone rubber faces numerous challenges in extreme environments in this field. From the ultra - low temperature and strong radiation at high altitudes to the ultra - high temperature when spacecraft re - enter the atmosphere, the performance of silicone rubber is directly related to the success or failure of aerospace missions. In - depth research on its adaptability in extreme environments and the formulation of targeted optimization strategies are important steps in promoting the development of aerospace technology.
In the high - altitude environment, low temperature is one of the primary challenges faced by silicone rubber. The temperature in the stratosphere can drop to - 50 °C or even lower. Under such low temperatures, the molecular chain mobility of ordinary silicone rubber is significantly reduced, the material becomes hard and brittle, and its elasticity and flexibility decline sharply. For example, if the sealing parts of the fuel delivery pipelines of an aircraft use conventional silicone rubber, the sealing may fail in a low - temperature environment, resulting in fuel leakage and seriously threatening flight safety. To improve the performance of silicone rubber at low temperatures, researchers have introduced special flexible groups, such as polyether segments, into the silicone rubber molecular chain through chemical modification. These flexible groups can increase the movement space of the molecular chain, lower the glass transition temperature of the material, and enable silicone rubber to maintain a certain degree of elasticity and flexibility at low temperatures. Experiments show that the tensile strength and elongation at break of silicone rubber modified in this way can still remain at a relatively high level in a low - temperature environment of - 60 °C, effectively ensuring the sealing performance.
At the same time, strong radiation in the high - altitude environment is also an important factor affecting the performance of silicone rubber. High - energy particles in cosmic rays, such as protons, electrons, and heavy ions, interact with silicone rubber molecules, leading to molecular chain scission, cross - linking, or the formation of free radicals. These changes will deteriorate the physical properties of silicone rubber, such as increased hardness, reduced elasticity, and decreased insulation performance. For the external structural parts and sealing materials of satellites and other spacecraft, the long - term effect of strong radiation may cause the material to fail prematurely. To solve this problem, researchers have adopted the method of adding radiation - resistant fillers. For example, fillers with radiation - resistant properties such as nano - titanium dioxide and zinc oxide are uniformly dispersed in the silicone rubber matrix. These fillers can absorb or scatter high - energy particles, reducing their damage to the silicone rubber molecular chain. Studies have found that the performance degradation rate of silicone rubber added with an appropriate amount of nano - titanium dioxide is significantly slowed down in a simulated strong radiation environment, and its service life is significantly extended.
When the spacecraft re - enters the atmosphere, silicone rubber has to withstand the test of ultra - high temperature. The surface temperature of the spacecraft can soar to several thousand degrees Celsius in an instant. Under such extreme high temperatures, silicone rubber must have good thermal stability and heat - insulation performance to protect the internal precision instruments and structural components. Traditional silicone rubber is prone to decomposition and combustion at high temperatures and cannot meet this requirement. Therefore, researchers have developed high - temperature - resistant silicone rubber materials. By introducing a large number of aryl, heterocyclic and other high - temperature - resistant groups into the molecular structure, the thermal decomposition temperature of silicone rubber is increased. At the same time, through special filling technology, ceramic fibers, vermiculite, etc. with high heat - insulation performance are filled into the silicone rubber to form a composite heat - insulation material. This high - temperature - resistant composite silicone rubber can form a stable heat - insulation carbon layer at high temperatures, effectively blocking the heat transfer to the inside. Experiments show that when such materials are impacted by a high - temperature flame of 1500 °C, the temperature on the back side rises slowly, which can provide reliable thermal protection for the internal structure.
In addition, in aerospace applications, silicone rubber also needs to have good resistance to space - environment aging. Long - term exposure to a high - vacuum, microgravity, and complex space plasma environment, silicone rubber will gradually age and its performance will decline. To improve its aging resistance, in addition to optimizing the molecular structure and adding protective fillers, the surface of silicone rubber can also be specially treated. For example, plasma treatment technology is used to introduce a film with anti - oxidation and anti - corrosion properties on the surface of silicone rubber, enhancing its ability to resist the erosion of the space environment. Through these comprehensive optimization strategies, the adaptability of silicone rubber in aerospace extreme environments has been significantly improved, providing a strong material support for the development of the aerospace industry.
Ultralow Hardness Silicone rubber
