In the aerospace industry, the selection of materials for aircraft hydraulic system seals requires a comprehensive consideration of temperature resistance, oil resistance, mechanical strength, and environmental adaptability. The following is an analysis of key material types and their properties:

1. Silicone Rubber
Temperature Resistance: -100°C to 300°C (special grades can reach 400°C), suitable for extreme temperature environments.
Advantages: The Si-O backbone structure provides excellent high and low temperature resistance and outstanding aging resistance, making it suitable for sealing in vacuum environments such as satellite solar panels.

Applications: High-temperature engine environments (medium-phenyl/phenylene silicone rubber) or low-temperature engine environments (methyl vinyl silicone rubber).

2. Fluororubber (FKM)
Temperature Resistance: -20°C to 250°C, with short-term exposure to 300°C.
Advantages: Excellent oil resistance, particularly suitable for petroleum-based hydraulic fluid systems, and strong chemical resistance. Applications: High-temperature engine oil seals and hydraulic system seals.

3. Nitrile (NBR)
Temperature range: -55°C to 130°C.
Advantages: A higher acrylonitrile content improves oil and wear resistance, but reduces cold resistance.
Limitations: Not resistant to phosphate ester hydraulic fluids and ozone aging.

4. Fluorosilicone (FVMQ)
Temperature range: -55°C to 230°C.
Advantages: Combines the heat resistance of silicone rubber with the oil resistance of fluororubber, making it suitable for sealing electrical components in fuel systems.
Application example: HM804 two-component fluorosilicone sealant, widely used in China's aviation industry.

5. Other materials
Ethylene propylene diene rubber (EPDM): Excellent weather resistance but poor oil resistance, making it suitable for sealing non-oily media. Teflon (PTFE): Temperature resistant from -196°C to 300°C, low friction coefficient, but caution regarding charge accumulation.

Material Selection Recommendations
High-temperature environments: Silicone rubber or fluororubber are preferred.
High oil resistance requirements: Fluororubber or nitrile rubber (avoid phosphate ester hydraulic fluids).
Overall performance: Fluorosilicone rubber is an ideal choice for fuel system seals.