Main properties of fluoro rubber O-rings

Generally, the matching strength of 26 fluoro rubber O-ring is 10-20Mpa, the elongation is 150-300%, and the tear strength is between 20-40kn / m, but its elasticity is poor.
The friction coefficient of fluorine rubber O-ring is 0.8, which is smaller than that of nitrile rubber (0.9-1.5).
High temperature resistance
Fluorine rubber O-rings and silicone rubber have high temperature resistance. F26-41 fluoro rubber O-ring can work at 200-250 ℃ for a long time and short-term at 300 ℃. The heat resistance of f246 is better than that of F26.
The tensile strength and hardness of fluoro rubber O-rings decreased with the increase of temperature. The change characteristics of tensile strength and hardness are as follows: below 150 ℃, they decrease rapidly with the increase of temperature; between 150 ℃ and 260 ℃, they decrease slowly with the increase of temperature.
Corrosion resistance
Fluoro rubber O-rings have excellent corrosion resistance. It has excellent stability to organic liquids, different fuel oils and lubricating oils. It has good corrosion resistance to most inorganic acids, hydrocarbons, benzene and toluene. It is not suitable for low molecular weight esters, ethers, ketones and some amines.
Resistance to hot water and superheated steam
The stability of rubber to hot water depends not only on the bulk material, but also on the compounding of rubber. For fluoro rubber O-ring, peroxide vulcanized fluoro rubber O-ring is better than amine and phenol vulcanization system compounds. It should be said that the resistance to hot water and superheated steam of fluoro rubber O-ring is not as good as that of ethylene propylene rubber. The volume change of O-ring is less than 10% after soaking in 180 ℃ for 24h in superheated water, and the physical properties do not change much.
Compression set performance
Fluorine rubber O-rings are used in sealing at high temperature, compression deformation is its key performance. The reason why Viton O-ring has been widely used is due to the improvement of compression deformation. DuPont company of the United States has been committed to improving the compression deformation resistance of fluoro rubber O-rings since the 1960s and 1970s, and has achieved remarkable results.
Low temperature resistance
The low temperature resistance of fluoro rubber O-rings are general, and its limit temperature of elasticity is - 15-20 ℃. With the decrease of temperature, its tensile strength increases, and it appears strong and tough at low temperature. The brittleness temperature of 2 mm thick standard sample is about - 30 ℃, 1.87 mm is - 45 ℃, 0.63 mm is - 53 ℃, and 0.25 mm is - 69 ℃. Generally, the service temperature of fluoro rubber O-ring can be slightly lower than the brittleness temperature. For example, the use temperature of mil-25879d is - 40-205 ℃. The temperature limit of fluoro rubber O-ring used in Aeroengine abroad is - 35 ℃.
Weathering and ozone resistance
After 10 years of natural storage, the performance of vitona is still satisfactory. In the air with 0.01% ozone concentration, there was no obvious cracking after 45 days. Its weather aging resistance and ozone resistance are satisfactory.
Electrical properties
The electrical insulation performance of the fluoro rubber O-ring is not very good, and it is only suitable for low-frequency and low-voltage applications. Temperature has a great influence on its electrical properties. When the temperature rises from 24 ℃ to 184 ℃, its insulation resistance decreases 35000 times.
Air permeability
The gas solubility of fluoro rubber O-ring is relatively large, its diffusion speed is relatively small, and the total gas permeability is very small. In the O-ring of fluoro rubber, the air permeability of vulcanizate decreases with the addition of filler, which is favorable for vacuum sealing. If suitable, fluoro rubber O-ring can solve 10-7pa vacuum sealing.
Fire resistance
Fluorine rubber O-ring can burn in case of fire and self extinguish when leaving the fire.