I. Lubrication mechanism
Fluorosilicone oil is a polysiloxane with trifluoropropyl (-CF₃) introduced into the side chain. It retains the high and low temperature resistance (-40℃～240℃) of methyl silicone oil while giving it extremely strong hydrophobicity and chemical inertness.
‌Surface self-assembled film formation‌: The outer layer of the molecular film of -CF₃ is adsorbed on the surface of the friction pair, which significantly reduces the surface free energy (as low as 20mN/m), reduces the interfacial adhesion, and achieves a low friction coefficient.
‌Friction interface behavior‌
‌Low load conditions‌: The -CF₃ molecular film isolates the friction pair through physical adsorption, reducing direct contact wear.
‌High load/extreme pressure conditions‌: Friction heat triggers the reaction of fluorine/silicon active components with metals to generate chemical reaction films such as ferric fluoride and silicate, enhancing the anti-wear and extreme pressure properties.

2. Tribological properties
1. ‌Basic lubricity comparison
Lubricant type ‌                           Friction coefficient ‌              Extreme pressure (four-ball test) ‌                Temperature resistance
Fluorosilicone oil (unmodified)       Low (about 0.12)                Better than dimethyl silicone oil                   -40℃～240℃             
Chlorine-containing modified
fluorosilicone oil                          Lower (about 0.08) ‌            Better than ester oil‌                                    Good high-temperature
                                                                                                                                                    oxidation  stability
Dimethyl silicone oil                     Medium                             Poor                                                       -50℃～200℃
Mineral oil                                  High                                 Medium                                                   -20℃～150℃
Note: In the four-ball test, the maximum non-seizure load of fluorosilicone oil is significantly higher than that of traditional silicone oil, and the extreme pressure after chlorine-containing modification exceeds that of ester oil.

2. Modification and synergistic approach
Additive optimization:
Addition of tri(methylsilyl)phosphate: Reduce the wear spot diameter of steel balls from 1.15mm to 0.59mm, and the friction coefficient to 0.125.
Introduction of chlorine-containing compounds (such as 1,3-bis(dichloromethyl)siloxane): Generate a ferric chloride friction film to improve extreme pressure resistance without metal corrosion.
Molecular structure design:
Introduce chlorine elements into the γ-trifluoropropyl side chain to enhance high-temperature lubrication stability.

III. Performance advantage scenarios
Extreme environment adaptability
High temperature: Continuous lubrication above 121°C (such as aircraft engine bearings); Low temperature: Maintain fluidity at -40°C (polar equipment lubrication); Chemical corrosion environment: Resistant to fuel, solvents, acids and alkalis (chemical pump seal lubrication). ‌Application in special fields‌

‌Aerospace‌: rocket propellant seals, high-speed gyroscope bearings (high temperature resistance + chemical corrosion resistance);
‌Precision machinery‌: watch gears, micromotor bearings (low surface energy reduces friction loss);
‌Vacuum system‌: semiconductor manufacturing equipment vacuum pump (low volatility + no residue).

IV. Performance limitations and improvement directions‌
‌Limitations‌: The lubricity of unmodified fluorosilicone oil is weaker than that of ester oil, and its compatibility with some additives is poor.
‌Improvement‌:
Compound lubrication formula (such as fluorosilicone oil + perfluoropolyether) improves high-temperature and high-speed stability;
Develop phenyl/chlorine synergistic modified molecular structure to optimize oxidation resistance and shear stability.
In summary, fluorosilicone oil achieves efficient lubrication through the dual effects of -CF₃ molecular film and tribochemical reaction, and its modified products have surpassed the comprehensive performance of traditional lubricants under extreme working conditions.