Fluorosilicone oil exhibits extremely low volatility characteristics in high vacuum systems.  Its volatile components remain below 5% after heating at 200°C for 4 hours, and it can operate stably for extended periods in high vacuum environments below 10⁻⁸ Pa without significant volatile losses, ensuring reliable system operation.

I. Performance of Fluorosilicone Oil's Low Volatility Characteristics
Empirical Volatility Data:
The volatile components of fluorosilicone oil after heating at 200°C for 4 hours are <5%, significantly lower than that of ordinary silicone oil.
Perfluoropolyether oil (PFPE) shows no significant change in viscosity after heating at 250°C for 100 hours, maintaining stable color, with only a slight increase in acid value.
Fluorinated silicone grease has a volatile component of ≤0.05% under 200°C and 24 hours, which is almost negligible.
High Vacuum Environment Adaptability:
In high vacuum environments below 10⁻⁸ Pa (such as semiconductor wafer manufacturing and aerospace equipment), fluorosilicone oil exhibits extremely low volatile loss, ensuring long-term stable operation of the system.
The low vapor pressure characteristics of fluorosilicone oil make it particularly suitable for long-term lubrication in high vacuum systems, preventing system pressure increase or contamination of precision components due to volatilization.
Temperature Stability:
Fluorosilicone oil maintains stable performance over a wide temperature range of -60°C to 200°C, with some high-end products having a temperature range of -80°C to 300°C.
Under high-temperature conditions (such as above 200°C), fluorosilicone oil still maintains low volatility and does not decompose or volatilize rapidly like ordinary silicone oil.

II. Analysis of the Causes of Low Volatility Characteristics
Molecular Structure Advantages:
Fluorosilicone oil introduces trifluoropropyl groups into the siloxane chain, forming stable C-F bonds (bond energy approximately 485 kJ/mol), significantly improving molecular thermal stability.
The high electronegativity of fluorine atoms creates an "electron shielding effect," effectively protecting the silicon-oxygen bond from thermal decomposition and reducing the tendency to volatilize at high temperatures.
Surface Characteristics Contribution:
Fluorosilicone oil has a low surface tension of 20-24 mN/m, which allows it to form a durable lubricating film on metal surfaces, reducing the escape of oil molecules into the gas phase. The low refractive index (1.38-1.40) of fluorosilicone oil makes it less likely to produce volatile residues in optical device coating applications.
Chemical Stability:
Fluorosilicone oil exhibits excellent chemical inertness and does not react with strong corrosive media such as concentrated nitric acid, concentrated sulfuric acid, and concentrated hydrochloric acid below 100°C.
This stability prevents it from being catalytically decomposed by residual gases or trace contaminants in high vacuum systems, thus maintaining low volatility.

III. Application Value in High Vacuum Systems
Semiconductor Manufacturing:
As a vacuum pump lubricant, it is used for handling reactive gas media, and its low volatility ensures that it does not contaminate the wafer surface.
Suitable for long-term lubrication of high-vacuum equipment such as rotary vane pumps, turbomolecular pumps, and diffusion pumps, reducing maintenance frequency.
Aerospace and Defense Applications:
In the high-vacuum environment of aerospace equipment, the low volatility of fluorosilicone oil ensures the reliability of long-term missions, preventing equipment failure due to lubricant evaporation.
As a floating medium in inertial navigation systems, its stable physical properties guarantee navigation accuracy.
Industrial Vacuum Systems:
In the vacuum systems of chemical equipment, fluorosilicone oil not only provides lubrication but also acts as a sealing oil, and its low volatility ensures the integrity of the system seal.
Suitable for high-vacuum environments in oxygen industrial equipment, maintaining stability even under pure oxygen conditions.

IV. Comparative Advantages with Other Materials
Table
Property | Fluorosilicone Oil | Ordinary Silicone Oil | Perfluoropolyether Oil
Volatile Content (200℃, 4h) | <5% | 8-15% | <3%
Temperature Range | -60～200℃ | -50～200℃ | -80～300℃
High Vacuum Stability | 10⁻⁸ Pa level | 10⁻⁶ Pa level | 10⁻⁸ Pa level
Solvent Resistance | Excellent | General | Excellent
Price | Medium | Low | High
Fluorosilicone oil provides the best balance point in high vacuum systems: compared to ordinary silicone oil, it has a wider temperature range and lower volatility; compared to perfluoropolyether oil, it is more economical while still maintaining sufficiently low volatility. For high-vacuum systems requiring long-term stable operation within a temperature range of -60℃ to 200℃, fluorosilicone oil is an ideal choice, especially for critical applications such as semiconductor manufacturing, aerospace equipment, and chemical vacuum systems.