The
sealing material should meet the requirements of the sealing function. Due to the different sealed media and the different working conditions of the equipment, the
sealing materials are required to have different adaptability. The requirements for sealing materials are generally:
1 The material is dense and not easy to leak;
2 Have appropriate mechanical strength and hardness;
3 Good compressibility and resilience, and small permanent deformation;
4 No softening and decomposition at high temperature, no hardening or brittle cracking at low temperature;
5 Good corrosion resistance, can work for a long time in acid, alkali, oil and other media, its volume and hardness change is small, and it does not adhere to the metal surface;
6 Small friction coefficient and good wear resistance;
7 Has the flexibility to combine with the sealing surface;
8 Good aging resistance and durable;
9 The manufacturing process is convenient, the price is relatively cheap, and it is easy to obtain materials.
The earliest dynamic seal material was GCI (grey cast iron). Rubber is the most commonly used static sealing material, common ones are: fluorine rubber, silicone rubber, EPDM and so on.
General rubber seal products are increasingly used in defense, chemical, coal, petroleum, metallurgy, transportation, and machinery manufacturing industries, and have become basic parts and accessories in various industries.
In addition to rubber, graphite and various sealants are suitable for sealing materials. Nowadays, some seals use plastic as raw material, mainly: PEEK, PI, PTFE and PAI. These high-temperature polymers will become the trend of the future seal manufacturing process, and the price of seals will become more and more expensive.
