Phenyl silicone rubber, due to its excellent wide-temperature range stability, high-temperature resistance, and low compression set characteristics, has become a key material in modern aerospace engine sealing systems, especially suitable for sealing applications requiring extreme temperature variations and high reliability.
I. Core Performance Advantages
1. Wide Temperature Range Sealing Capability
Operating temperature range: Phenyl silicone rubber maintains stable elasticity in extreme temperature ranges from -100℃ to +70℃, and some modified products can even maintain good sealing performance at temperatures as low as -110℃.
High-temperature resistance: In the high-temperature areas of aerospace engines, phenyl silicone rubber can operate stably in environments up to 400℃ without significant performance degradation, far exceeding the temperature resistance limit of ordinary silicone materials.
Temperature cycle adaptability: During the frequent temperature changes in aerospace engines, phenyl silicone rubber does not easily harden or become brittle, effectively coping with drastic changes from low temperatures at high altitudes to high engine temperatures.

2. Excellent Sealing Stability
Low compression set: Even under prolonged pressure or heat, phenyl silicone rubber maintains a low compression set rate, ensuring stable sealing gaps and preventing increased leakage due to seal aging.
High resilience: Under engine vibration and pressure fluctuations, phenyl silicone rubber can quickly recover its original shape, maintaining the sealing effect, making it particularly suitable for the dynamic working environment of aerospace engines.
Low gas permeability: As a sealing material, phenyl silicone rubber has extremely low gas permeability, effectively preventing the leakage of high-temperature combustion gases, fuel, and hydraulic oil.

3. Environmental Adaptability
Weather resistance: Phenyl silicone rubber can resist long-term exposure to ultraviolet radiation, ozone, and moisture, and is not prone to aging or deterioration, ensuring the long-term reliability of aerospace engines under various climatic conditions.
Chemical corrosion resistance: It has good stability against common chemicals in aerospace engines, such as jet fuel, hydraulic oil, and oxidizers, and will not cause seal failure due to chemical corrosion.
Radiation resistance: High-phenyl silicone rubber can withstand 2.58 × 10⁴ C/kg gamma ray radiation, making it suitable for aerospace engine sealing in special environments. II. Specific Applications in Aero Engines
1. Combustion Chamber and Turbine Sealing
Combustion chamber sealing: Phenyl silicone rubber is used for high-temperature seals between the combustion chamber and the turbine, withstanding the erosion of high-temperature combustion gases and preventing gas leakage that would lead to reduced efficiency.
Turbine blade sealing: Phenyl silicone rubber seals are used between the turbine blades and the casing to reduce airflow leakage, improve turbine efficiency, and adapt to high-temperature and vibration environments.
2. Hydraulic and Fuel System Sealing
Hydraulic system sealing: Used for sealing components such as engine hydraulic pumps and hydraulic cylinders, maintaining good sealing performance under high temperature and high pressure, preventing hydraulic oil leakage.
Fuel system sealing: Provides reliable sealing in critical parts such as fuel pumps, fuel lines, and fuel injectors, and withstands long-term immersion in jet fuel.
3. Engine Peripheral Sealing
Intake duct sealing: Phenyl silicone rubber seals are used at the connection between the engine intake duct and the fuselage to prevent external air leakage and ensure intake efficiency.
Exhaust system sealing: Used for high-temperature sealing of engine exhaust pipes, withstanding the erosion of high-temperature exhaust gases and preventing leakage that would affect engine performance.
Bearing housing sealing: Provides efficient sealing in the engine bearing housing to prevent lubricating oil leakage and the entry of external contaminants.
4. Combination with New Sealing Technologies
Brush seal technology: Phenyl silicone rubber can be combined with brush seal technology. Brush seals consist of densely arranged metal wires, and the leakage rate is only 1/5-1/10 of traditional labyrinth seals. Phenyl silicone rubber can be used as an auxiliary sealing material for brush seals.
Multi-stage sealing system: In high-performance aero engines, phenyl silicone rubber is often used in the key sealing layer of multi-stage sealing systems, working in conjunction with other sealing technologies to achieve lower leakage rates.

III. Comparison with Other Sealing Materials
1. Comparison with Fluorocarbon Rubber (FKM)
Advantages: Phenyl silicone rubber has better low-temperature performance (-100℃ vs -20℃) and a wider temperature range (-100℃ to 400℃ vs -20℃ to 204℃).
Disadvantages: It is slightly inferior to fluorocarbon rubber in terms of oil resistance. For applications involving long-term contact with fuels with high aromatic hydrocarbon content, special modification may be required. 2. Comparison with Perfluoroelastomer (FFKM)
Advantages: Phenyl-based raw rubber has lower cost and better processing performance, and comparable sealing performance in the low to medium temperature range.
Disadvantages: The high-temperature limit is lower than FFKM (400℃ vs 327℃), limiting its application in extremely high-temperature areas.
3. Comparison with Traditional Silicone Rubber
Advantages: Phenyl-based raw rubber has superior high-temperature resistance (400℃ vs 200℃), better radiation resistance, and better low-temperature performance (-100℃ vs -60℃).
Advantages: The phenyl structure disrupts the regularity of the siloxane chain, reducing the crystallization temperature and glass transition temperature, allowing the material to maintain flexibility at low temperatures.

IV. Application Selection and Precautions
1. Material Selection Recommendations
Low-temperature environment (below -50℃): Prioritize low-phenyl silicone rubber (phenyl content 5-10 mol%), which maintains flexibility and elasticity at -100℃.
High-temperature environment (above 250℃): Choose medium-to-high phenyl silicone rubber (phenyl content 15-50 mol%), which has better heat stability and self-extinguishing properties.
Radiation environment: Choose high-phenyl silicone rubber, which can withstand high doses of γ-ray radiation.
2. Application Precautions
Installation process: When installing aircraft engine seals, the compression ratio must be strictly controlled, usually 15-25%, to avoid permanent deformation caused by over-compression.
Surface treatment: The sealing surface should be smooth and free of scratches. A surface roughness of Ra≤0.8μm is recommended to ensure optimal sealing performance.
Pressure balance: In areas with high pressure differences, a pressure balancing structure should be designed, such as "connecting a balance pipe from the side of the static component flange" as mentioned in the text, to alleviate the pressure on the seal.
3. Future Development Trends
Material innovation: Develop modified materials such as phenyl vinyl silicone rubber to further improve high and low-temperature resistance, radiation resistance, and mechanical properties.
Structural optimization: Combine with new sealing technologies such as brush seals to develop composite sealing systems that adapt to centrifugal effects and large impact loads.
Intelligent manufacturing: Adopt precision molding, surface treatment, and composite material technologies to improve the performance consistency and service life of seals. Due to its unique wide temperature range performance and reliability, phenyl silicone rubber has become an indispensable sealing material in modern high-performance aero-engines. As aero-engines develop towards higher performance and longer lifespan, the performance optimization and application innovation of phenyl silicone rubber materials will continue to advance, providing crucial support for improved aviation safety and efficiency.