I. Basic properties of phenyl silicone oil
Phenyl silicone oil (Phenyl Methyl Silicone Oil) is a lubricant based on phenyl and methyl substituted polysiloxanes, with the following key properties:
High and low temperature resistance: can work stably in the range of -60℃ to 300℃.
Low surface tension: easy to form a uniform lubricating film and reduce the friction coefficient.
Chemical stability: excellent tolerance to acids, alkalis, oxidants, etc.
Electrical insulation: suitable for friction parts in electronic equipment.

II. Key indicators of tribological performance research
Tribological performance is usually evaluated by the following indicators:
Friction coefficient (μ): reflects the ability of lubricants to reduce friction.
Wear rate (W): the volume or mass lost by a material due to friction.
Lubricating film stability: the ability of a lubricating film to maintain under high temperature and high pressure.
Extreme pressure resistance: the ability to prevent direct metal contact under heavy load conditions.

III. Tribological performance of phenyl silicone oil
1. Friction coefficient
Low friction characteristics: The phenyl group in the molecular chain of phenyl silicone oil increases the steric hindrance between molecules and reduces the intermolecular force, thereby reducing the friction coefficient.
Experimental data: In the steel-steel friction pair, the friction coefficient of phenyl silicone oil can be as low as 0.05-0.10, which is significantly lower than that of mineral oil (0.1-0.2).
2. Wear rate
Anti-wear performance: The lubricating film formed by phenyl silicone oil can effectively isolate the surface of the friction pair and reduce wear.
Case: In the gear transmission experiment, the wear of the gear lubricated with phenyl silicone oil is reduced by 30%-50% compared with the gear lubricated with mineral oil.
3. Lubricating film stability
High temperature stability: Phenyl silicone oil is not easy to decompose at high temperature, and the lubricating film remains intact.
Comparison: At 200°C, the lubricating film thickness of phenyl silicone oil changes by less than 10%, while mineral oil may completely fail.
4. Extreme pressure resistance
Synergistic effect of extreme pressure additives: Phenyl silicone oil is often used in combination with extreme pressure additives (such as sulfur and phosphorus compounds) to improve extreme pressure resistance.
Experiment: In the four-ball extreme pressure test, the load-bearing capacity (P_B value) of phenyl silicone oil + extreme pressure additives can reach 800-1000N, which is much higher than pure phenyl silicone oil (300-500N).

IV. Application advantages of phenyl silicone oil
Application field Advantages Cases
Aerospace High and low temperature resistance, low volatility, anti-oxidation Lubrication of aircraft engine bearings
Electronic equipment Electrical insulation, low friction, no corrosion Hard disk drive spindle lubrication
Precision machinery High precision, low wear, long life Lubrication of optical instrument guide rails
High temperature environment Good thermal stability, long-lasting lubricating film Lubrication of glass melting furnace rollers

V. Research challenges and future directions
Environmental friendliness:
Phenyl silicone oil has poor biodegradability, and it is necessary to develop degradable substitutes or improve recycling technology.
Research direction: Nano additives enhance lubrication performance and reduce usage.
Cost and performance balance:
Phenyl silicone oil is expensive, and the formula needs to be optimized to reduce costs.
Case: Improve performance and reduce the amount of phenyl silicone oil by adding low-cost fillers (such as graphene).
Performance under extreme conditions:
Further research is needed on tribological properties under extreme environments such as ultra-high vacuum and strong radiation.
Multi-physics field coupling research:
Combined with thermal-mechanical-chemical multi-field coupling, the lubrication mechanism of phenyl silicone oil under complex working conditions is revealed.

VI. Conclusion
Phenyl silicone oil has an irreplaceable position in the field of high-end lubrication due to its excellent tribological properties. Future research should focus on:
Improve environmental friendliness;
Balance between reducing costs and improving performance;
Expand applications under extreme conditions.