What are the main materials of mechanical seal end seal (friction pair)?

Sealing performance and service life of mechanical seals, especially with the end seal (friction pair) materials, auxiliary sealing materials and spring materials.

1, graphite

Graphite has the advantages of good corrosion resistance and self-lubrication, small friction coefficient, good heat resistance and impact and easy processing.

The disadvantage is low mechanical strength, there are pores.These two shortcomings of graphite can be improved by impregnation and carburizing.Impregnated graphite can be divided into two kinds: impregnated resin and impregnated metal.Immersed resin graphite corrosion resistance is good, but not high temperature (temperature resistance of about 170-200 ℃);Impregnated metal graphite has good temperature resistance (high temperature resistance of bronze, aluminum, lead, etc., up to 400~500℃), but poor corrosion resistance.Graphite is the most widely used non-metallic material, used as the moving ring of the middle and low speed mechanical seal and the static ring of the high speed mechanical seal.Good graphite, the naked eye looks dense, finger touch is not off powder, not dyed black fingers.

2, ceramic

The advantages of ceramics are good corrosion resistance, high hardness, good wear resistance, the disadvantage is brittleness and hardness is too high and difficult to process.Application is more alumina ceramics, there are metal ceramics.Ceramics are mostly used in corrosive medium and low speed.

3, tungsten carbide alloy

By tungsten carbide, titanium carbide and other high hardness, high melting point of metal carbide, is to add binder powder metallurgy method, pressing sintering molding.Advantages are high hardness, strength.Wear resistance, high temperature resistance, corrosion resistance, low coefficient of linear expansion, shortcoming is brittle, difficult processing.Tungsten carbide is the most widely used end face sealing pair material, mostly used as the static ring of medium and low speed mechanical seals, and the dynamic ring of high speed mechanical seals.

4. Hardfacing cemented carbide

Hardfacing cemented carbide on the sealing surface of carbon steel, chromium steel and chromium nickel steel has the advantages of high hardness, good wear resistance, good temperature resistance (below 500℃), good corrosion resistance or cavitation resistance, and the disadvantage is easy to produce pores, slag inclusion and uneven surface hardness.