When an aircraft travels through the atmosphere at several times the speed of sound, or a satellite executes a scientific exploration mission in deep space orbit hundreds of kilometers from Earth for more than a decade, every precision mechanical component on board faces unprecedented challenges. The extreme high vacuum, intense cosmic rays and ultraviolet radiation, and drastic temperature cycles ranging from -70°C to 250°C are enough to cause most conventional materials to fail. In this extreme environment, a special synthetic lubricant called phenyl silicone oil, with its extraordinary comprehensive performance, has become the "Special Forces Lubricant" ensuring the reliable operation of spacecraft.
Traditional mineral oils or ordinary silicone oils are highly volatile in the high vacuum of space. This volatility not only causes the lubricant to be rapidly lost, leading to dry friction and seizure of bearings, gears, and other moving pairs, but more seriously, the volatiles can condense into a film on the surfaces of cold optical lenses, solar panels, or infrared sensors, causing optical performance degradation or even system paralysis. Phenyl silicone oil fundamentally solves this problem. Its molecular structure introduces rigid phenyl rings (C₆H₅-) as side groups onto the polysiloxane backbone. The large volume and strong polarity of the phenyl ring greatly increase the intermolecular cohesion, giving phenyl silicone oil an ultra-low saturated vapor pressure. Even under ultra-high vacuum of 10⁻⁶ Pa and high temperatures of 200°C over a long period, its mass loss rate is negligible, ensuring that its lubrication life matches the spacecraft's mission duration.
In addition to its outstanding anti-volatility, phenyl silicone oil also boasts excellent radiation resistance and a wide liquid temperature range. The phenyl ring structure can effectively absorb and dissipate the impact energy of high-energy particles, preventing backbone breakage and allowing it to maintain stable viscosity and lubricating performance in strong radiation fields. This makes it the ideal choice for critical moving components such as gyroscopes, momentum wheels, antenna drive mechanisms, and solar array deployment hinges. These components are the core of a spacecraft's attitude control and power supply; their failure would doom the entire mission. The lubricating film formed by phenyl silicone oil not only significantly reduces the friction coefficient and wear but also forms a protective barrier on the metal surface, inhibiting cold welding (the phenomenon where clean metal surfaces in a vacuum directly contact and adhere).
