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Mechanical Seals Common Materials
Oct 25, 2018

Mechanical seals common materials

The sealing performance and service life of the mechanical seal are related to the material of each part, especially the material of the end seal (friction pair), the material of the auxiliary seal and the material of the spring.Here we introduce the material of the end face sealing friction pair

The friction pair materials are carbon, ceramic,tungsten carbide coating , tungsten carbide alloy, Silicone carbide, tin bronze, steel bonded carbide, stainless steel and etc... The properties of commonly used materials are as follows:

1. Tungsten Carbide Alloy Metal carbides with high hardness and high melting point, such as tungsten carbide and titanium carbide, are formed by powder metallurgy with binder and pressed and sintered. The advantage is that the hardness and strength are very high. Wear resistance, high temperature resistance, corrosion resistance, low coefficient of linear expansion, the disadvantage is that it is brittle and difficult to process. Tungsten carbide is the most widely used face seal material, and is used as a stationary seat ring for medium and low speed mechanical seals and a rotary face ring for high speed mechanical seals.

2. Carbon --- Carbon has the advantages of good corrosion resistance and self-lubrication, low friction coefficient, good thermal shock resistance and easy processing. The disadvantage is low mechanical strength and porosity. These two disadvantages of graphite can be improved by impregnation and carburization. Impregnated graphite can be divided into two types: impregnated resin and impregnated metal. Impregnated graphite graphite has good corrosion resistance, but it is not resistant to high temperature (temperature resistance is about 170-200 degrees); impregnated metal graphite has good temperature resistance (dip bronze, aluminum, lead and other high temperature resistance up to 400~500 degrees, but corrosion resistance Poor sex. Carbon graphite is the most widely used non-metallic material used as a stationary seat ring for medium and low speed mechanical seals and high speed mechanical seals. Good carbon graphite, it looks dense by eyes, t, will not easily make fingers too black.

Mechanical seal carbon rod

3. Ceramics ---The advantages of ceramics are good corrosion resistance, high hardness and good wear resistance. The disadvantages are high brittleness and high hardness, which is difficult to process. Most of the applications are alumina ceramics, as well as cermets. Ceramics are mostly used in corrosive media, medium and low speed applications.

4. Surfacing hard alloys--- Hard alloys are deposited on the sealing surfaces of carbon steel, chrome steel and chrome-nickel steel. The advantages are high hardness, good wear resistance, good temperature resistance (below 500 degrees), corrosion resistance or Good cavitation, the disadvantage is easy to produce pores, slag inclusions and uneven surface hardness.

If you want to know how to choose materials,let us know~~`