Views: 2454 Author: Site Editor Publish Time: 2020-06-29 Origin: Site
Silicon carbide can be used under the working condition of high pressure, high speed, high temperature, corrosive medium and solid particle medium due to its good performance required for mechanical seals. Silicon carbide mechanical seals can replace traditional seals such as spring seals, pump seals, gland packings, non contacting mechanical seals, elastomer bellows seals, etc. The following describes the specific application of silicon carbide in the mechanical seal industry.
High pressure fluid exerts great load on the end face of mechanical seal, and the pressure stress on the end face is very high, which requires that the seal material must have high strength and rigidity. Silicon carbide is a kind of material with high strength and rigidity. Its elastic modulus is very high, and it is not easy to deform under high pressure. It can bear high pressure stress and meet the use requirements.
Because of the high linear speed, the thermal wear and vibration of the friction pairs are the main problems to be considered. Therefore, it is required that the density of the sealing material is small and the strength is high, so that the centrifugal force produced by the rotating ring at high speed is small, and the vibration and deflection caused by it are also small, so as to maintain the stable fit of the sealing end face. In addition, the material should have good heat resistance and thermal conductivity, in order to reduce the friction temperature of mechanical seal, reduce frictional wear, avoid thermal cracking and thermal deformation, so that the mechanical seal can maintain normal operation. According to the properties of silicon carbide, it can meet the requirements for material of high-speed mechanical seal.
High temperature will change the performance of friction pair materials, deform the seal face, reduce the hardness of the seal and reduce the service life of the seal. Silicon carbide has good heat resistance. At 1400℃, its bending strength is the same as that at room temperature. Therefore, silicon carbide can be used to make high temperature mechanical seals.
For mechanical seals used to seal corrosive medium, corrosive wear is the main cause of failure of friction pairs. Silicon carbide has good chemical stability and corrosion resistance, and can meet the requirements of corrosion resistant mechanical seals. Hot-pressed sintered silicon carbide exhibits good chemical stability even at 900℃ due to the formation of an oxide layer on its surface.
Many industrial fluid medium contain a large number of solid particles, which are easy to accumulate on the end face of the friction pair. These particles will not only cause serious wear of the seal face, but also heat the seal face and cause thermal cracking. Silicon carbide has the characteristics of high hardness and wear resistance, so it is difficult for silicon carbide to be worn by these solid particles, which can ensure the performance of mechanical seal.