Aerospace vehicles need to operate in extreme environments (high temperature, low temperature, high vacuum, strong radiation) for a long time, which imposes strict requirements on material performance. Ethyl silicone oil, with its unique molecular structure, has become a key material for solving problems such as thermal barrier, cold brittleness, and radiation damage. This article will analyze the irreplaceability of ethyl silicone oil from three extreme scenarios.
1、 Rocket Engine: A "Liquid Shield" Resistant to 2000 ℃ Thermal Shock
The rocket engine turbopump needs to withstand extreme working conditions where the gas temperature is greater than 2000 ℃ and the speed is greater than 20000rpm. Ethyl silicone oil achieves heat resistance protection through the following technologies:
Ceramic modification: Introducing silazane groups to form SiO ₂ - Si ∝ N ₄ ceramic layers on ethyl silicone oil at high temperatures, resulting in a threefold increase in thermal insulation performance.
Nanofiller Enhancement: Adding silicon carbide (SiC) nanoparticles (particle size<50nm) can increase the thermal conductivity of the material from 0.2W/(m · K) to 1.5W/(m · K) while maintaining flexibility.
Tests on a certain model of liquid rocket engine showed that after using modified ethyl silicone oil coating, the service life of turbopump bearings was extended from 5 starts to 20 starts.
2、 Deep space exploration: "flexible armor" against cosmic radiation
Spacecraft in geosynchronous orbit (GEO) must withstand strong radiation with an average annual radiation dose greater than 10 ⁷ rad. Ethyl silicone oil achieves radiation resistance through the following mechanisms:
Hydrogen bond shielding effect: The hydrogen atoms on the ethyl side chain can capture free radicals generated by high-energy particles, inhibiting material degradation. Experiments have shown that the tensile strength of unmodified silicone oil decreases by 50% after 10 ⁶ rad radiation, while that of ethyl silicone oil only decreases by 15%.
Metal oxide composite: doped with cerium oxide (CeO ₂) nanoparticles, which can be transformed through a valence change reaction (Ce ³ ⁺) ↔ Ce ⁴⁺) consumes oxidative substances generated by radiation. This composite material has been used for packaging the solar panels of the Tianwen-1 Mars probe.
3、 Ultra low temperature environment: lubricant to prevent material from becoming brittle
The nighttime temperature on the lunar surface is as low as -180 ℃, and traditional lubricants will solidify and fail. Ethyl silicone oil achieves ultra-low temperature lubrication through the following design:
Branching structure: Introducing branched groups such as isopropyl to reduce intermolecular forces and lower the pour point to below -70 ℃.
Perfluorination modification: Replacing ethyl with perfluoroethyl (C ₂ F ₅) can further extend the working temperature to -100 ℃. This material has been applied to the driving mechanism of the Chang'e-5 sampler.
4、 Technological Challenges and Future Directions
Long term stability: If the spacecraft has a lifespan of over 15 years in orbit, it is necessary to develop self-healing coating technology (such as microcapsule encapsulated repair agents) to extend the material lifespan;
Light weight demand: the density of ethyl silicone oil can be reduced from 0.97g/cm ³ to 0.2g/cm ³ through aerogel composite technology to meet the weight reduction demand of spacecraft.
According to data from the American Space Foundation, the global space industry will reach $424 billion in 2022, with material costs accounting for approximately 15%. As a key functional material, the technological breakthrough of ethyl silicone oil will directly promote the commercialization process in commercial aerospace, deep space exploration and other fields.
