Fluorocarbon rubber vs. silicone rubber for gasket - What is The Difference?

Fluorocarbon rubber offers superior chemical resistance and high-temperature stability, making it ideal for aggressive environments, while silicone rubber provides excellent flexibility, low-temperature performance, and weather resistance for general sealing applications. Selecting the appropriate gasket material depends on operating conditions such as temperature range, chemical exposure, and mechanical stress.

Table of Comparison

Introduction to Fluorocarbon and Silicone Rubber Gaskets

Fluorocarbon rubber gaskets are engineered from fluoropolymer compounds, offering exceptional chemical resistance, high temperature tolerance up to 250degC, and excellent durability in harsh environments. Silicone rubber gaskets provide superior flexibility, excellent low-temperature performance, and resistance to UV and ozone, making them ideal for sealing applications requiring elasticity and weather resistance. Both materials serve critical roles in industrial sealing, with fluorocarbon excelling in chemical and temperature-intensive applications, while silicone is preferred for its broad temperature range and resilience.

Chemical Composition and Structure Differences

Fluorocarbon rubber (FKM) contains a copolymer of vinylidene fluoride and hexafluoropropylene, providing high fluorine content that offers excellent chemical resistance and thermal stability compared to silicone rubber, which is composed of a silicon-oxygen backbone with organic side groups. The densely packed carbon-fluorine bonds in fluorocarbon rubber create a highly inert surface, making it resistant to oils, fuels, and solvents, while silicone rubber's flexible siloxane chain structure delivers superior temperature flexibility and resistance to oxidation. These distinct chemical compositions result in fluorocarbon rubber gaskets being preferred for aggressive chemical and high-temperature environments, whereas silicone rubber gaskets are favored for applications requiring broad temperature tolerance and low chemical reactivity.

Temperature Resistance Comparison

Fluorocarbon rubber (FKM) offers superior temperature resistance, typically ranging from -20degC to 230degC, making it ideal for high-heat applications. Silicone rubber can endure extreme temperatures from -60degC up to 200degC, excelling in low-temperature flexibility but slightly lower maximum heat tolerance than FKM. For gasket applications requiring higher temperature stability and chemical resistance, fluorocarbon rubber is generally the preferred choice.

Chemical Resistance Capabilities

Fluorocarbon rubber exhibits superior chemical resistance, especially against hydrocarbons, oils, fuels, and aggressive solvents, making it ideal for harsh chemical environments. Silicone rubber offers excellent resistance to ozone, weathering, and a wide temperature range but has limited resistance to fuels, oils, and many solvents compared to fluorocarbon rubber. Choosing between the two depends on the specific chemical exposure and temperature conditions the gasket will face.

Mechanical Properties and Durability

Fluorocarbon rubber exhibits superior chemical resistance and high-temperature stability up to 230degC, making it ideal for gaskets exposed to aggressive chemicals and extreme environments. Silicone rubber offers excellent flexibility and maintains elasticity in a wide temperature range from -60degC to 200degC, providing reliable sealing performance in both low and high-temperature applications. In terms of mechanical properties, fluorocarbon rubber delivers greater tensile strength and abrasion resistance, while silicone rubber excels in compression set resistance, enhancing long-term durability in dynamic sealing conditions.

Flexibility and Elasticity in Gasket Applications

Fluorocarbon rubber offers excellent chemical resistance but tends to have lower flexibility and elasticity compared to silicone rubber, making it less suitable for applications requiring high compressibility and dynamic movement. Silicone rubber provides superior flexibility and elasticity, enabling gaskets to maintain a consistent seal under varying temperatures and mechanical stresses. In gasket applications where flexibility and elastic recovery are critical, silicone rubber often outperforms fluorocarbon rubber despite the latter's robust chemical resilience.

Common Industrial Uses and Suitability

Fluorocarbon rubber (FKM) is widely used in gasket applications requiring exceptional chemical resistance, high-temperature stability up to 200-250degC, and excellent oil and fuel resistance, making it ideal for automotive, aerospace, and chemical processing industries. Silicone rubber gaskets offer superior flexibility, low-temperature performance down to -60degC, and excellent weathering and ozone resistance, which is suitable for food processing, medical devices, and electrical insulation applications. Industrial selection between fluorocarbon and silicone rubber gaskets depends on exposure to aggressive chemicals and temperature extremes versus the need for elasticity and environmental resilience.

Cost Considerations and Lifespan

Fluorocarbon rubber gaskets generally have higher upfront costs compared to silicone rubber due to their superior chemical resistance and temperature tolerance. The lifespan of fluorocarbon rubber gaskets often exceeds that of silicone rubber in harsh environments, providing better long-term value despite the initial investment. Silicone rubber gaskets offer a more affordable option with excellent flexibility and good performance in moderate temperature ranges but typically require more frequent replacement.

Environmental and Regulatory Compliance

Fluorocarbon rubber gaskets exhibit superior chemical resistance and meet stringent environmental regulations such as REACH and RoHS, ensuring low pollutant emissions and compliance with global standards for automotive and aerospace industries. Silicone rubber gaskets offer excellent thermal stability and ozone resistance, complying with FDA and EPA regulations for food-grade and medical applications, but may have limitations in volatile organic compound (VOC) emissions control. Selecting between fluorocarbon and silicone rubber for gaskets requires balancing regulatory frameworks focused on environmental safety, durability, and application-specific compliance mandates.

Choosing the Right Rubber for Your Gasket Needs

Fluorocarbon rubber offers excellent chemical resistance, high-temperature tolerance up to 200degC, and superior durability, making it ideal for aggressive environments and fuel handling applications. Silicone rubber excels in flexibility, low-temperature performance down to -60degC, and compression set resistance, suitable for sealing in food processing and medical devices. Selecting the right gasket material depends on specific requirements such as temperature range, chemical exposure, and mechanical properties to ensure optimal sealing performance and longevity.