Introduction to the knowledge and application cases of conductive FKM seals
I. Basic knowledge of conductive FKM seals
(I) Overview of FKM materials
FKM is the abbreviation of fluororubber (Fluoroelastomer), which refers to a synthetic polymer elastomer containing fluorine atoms on the carbon atoms of the main chain or side chain. Fluororubber has excellent heat resistance, chemical corrosion resistance, oil resistance and aging resistance. It can maintain good elasticity and sealing performance in the temperature range of -20℃ - 200℃, and has excellent tolerance to most organic solvents, strong acids, strong alkalis and other chemical media, which makes it widely used in many harsh industrial environments.
(II) Principle and preparation of conductive FKM seals
Conductive FKM seals are based on ordinary fluororubber and achieve conductive properties by adding conductive fillers. Common conductive fillers include carbon black, carbon fiber, metal powder (such as silver powder, copper powder), etc. These conductive fillers form a conductive network in the fluororubber matrix. When current passes through, electrons can be conducted in the conductive network, so that the seal has conductive properties.
Conductive FKM seals are usually prepared by a mixing process, that is, fluororubber raw rubber is fully mixed with conductive fillers, vulcanizers, accelerators and other additives in a mixing device (such as an open mixer, internal mixer), and then the seals of the desired shape are made by molding, extrusion and other molding processes. Finally, after vulcanization treatment, the rubber molecules undergo cross-linking reactions to form products with certain physical and mechanical properties and conductive properties.
(III) Performance characteristics of conductive FKM seals
1. Conductive properties: It has good conductivity, and its volume resistivity can generally be controlled within the range of 10¹ - 10⁶Ω·cm, which can meet the requirements of different application scenarios for conductive properties.
2. Sealing performance: It inherits the excellent sealing performance of fluororubber, can effectively prevent the leakage of liquids and gases, and ensure the normal operation of the equipment.
3. Environmental resistance: It still maintains the heat resistance, chemical corrosion resistance, aging resistance and other characteristics of fluororubber, and can be used for a long time in harsh environments such as high temperature and strong corrosion.
4. Mechanical properties: It has certain mechanical properties such as hardness, tensile strength and elongation at break, and can withstand certain pressure and deformation without damage.
2. Application cases of conductive FKM seals
(I) Electronic and electrical industry
1. Sealing of electronic product shells: In electronic products such as smartphones and tablets, conductive FKM seals are used to seal the shells. On the one hand, it can prevent dust, water vapor, etc. from entering the interior of the device and protect electronic components from damage; on the other hand, its conductive properties can play the role of electromagnetic shielding, preventing electromagnetic interference inside the device from affecting the normal operation of other devices, and also preventing external electromagnetic interference from entering the interior of the device, ensuring the stability and reliability of the device.
For example, a well-known brand of smartphones uses conductive FKM seals to seal the back cover and body of the phone during design. The seal not only effectively prevents the intrusion of dust and water vapor, but also shields the electromagnetic interference generated inside the phone inside the device through good conductive properties, improving the signal reception and transmission quality of the phone.
2. Sealing of electrical control cabinets: In electrical control cabinets, conductive FKM seals are used to seal cabinet doors, cable entrances and other parts. Since there are a large number of electrical components inside the electrical control cabinet, electromagnetic radiation will be generated during operation. The use of conductive FKM seals can shield these electromagnetic radiation inside the control cabinet to avoid interference with the surrounding environment and other equipment. At the same time, the good sealing performance of the seal can prevent external dust, moisture, etc. from entering the control cabinet and protect the normal operation of electrical components.
For example, in the electrical control cabinet of a large data center, conductive FKM seals are used. The seal effectively shields the electromagnetic interference generated by the electrical equipment in the control cabinet, while preventing the invasion of dust and moisture, ensuring the stable operation of the electrical system of the data center.
(II) Aerospace field
1. Aircraft engine sealing: The working environment of aircraft engines is extremely harsh, with high temperature and high pressure, and there is also corrosion from chemical media such as fuel and lubricating oil. Conductive FKM seals are used in aircraft engines to seal fuel systems, lubrication systems and other parts. Its heat resistance, chemical corrosion resistance and sealing performance can ensure the normal operation of various engine systems, while its conductive performance can prevent static electricity accumulation and avoid safety accidents caused by static electricity.
For example, the fuel pump seal of a certain model of aircraft engine uses conductive FKM seals. The seal can still maintain good sealing and conductivity under high temperature, high pressure and fuel corrosion environment, ensuring the safe and reliable operation of the fuel system.
2. Spacecraft electronic equipment sealing: In spacecraft, electronic equipment needs to work in extreme space environment, including high vacuum, strong radiation, high and low temperature alternation, etc. Conductive FKM seals are used to seal spacecraft electronic equipment, which can prevent damage to the equipment by external radiation and micrometeorites, and at the same time, its conductive properties can play the role of electromagnetic shielding, protecting electronic equipment from the influence of electromagnetic interference in space.
For example, in the electronic equipment compartment of a certain artificial satellite, conductive FKM seals are used for sealing. The seal effectively protects the electronic equipment during the launch and operation of the satellite, ensuring the normal communication and data transmission of the satellite.
(III) Automobile industry
1. Automobile electronic system sealing: Modern cars are equipped with a large number of electronic systems, such as engine control systems, body electronic control systems, etc. Conductive FKM seals are used to seal automotive electronic systems, which can prevent moisture, dust, etc. from entering electronic equipment, and at the same time play the role of electromagnetic shielding, protecting the electronic system from the influence of external electromagnetic interference, and improving the reliability and stability of automotive electronic systems.
For example, the battery management system of a new energy vehicle uses a conductive FKM seal. This seal not only prevents the intrusion of water vapor and dust, ensuring the normal operation of the battery management system, but also avoids the influence of external electromagnetic interference on the battery management system through electromagnetic shielding, improving the charging and discharging efficiency and safety of the battery.
2. Automobile engine seal: In automobile engines, conductive FKM seals are used to seal the intake manifold, exhaust manifold and other parts of the engine. Its heat resistance, oil resistance and sealing properties can prevent gas and liquid leakage in the engine, while its conductive properties can prevent static electricity accumulation and reduce the impact of electromagnetic interference generated during the operation of the engine on surrounding electronic equipment.
For example, the intake manifold seal of a high-performance automobile engine uses a conductive FKM seal. This seal can effectively seal the intake manifold under high temperature, high pressure and oil and gas corrosion, while reducing the electromagnetic interference generated by the engine and improving the anti-interference ability of the automotive electronic system.
