What material is used in the china mechanical seal?
The sealing performance and service life of the mechanical seal are related to the material of each part, especially the material of the end face seal (friction pair), the material of the auxiliary seal and the material of the spring. The commonly used materials for mechanical seals produced by China mechanical seal factory are as follows:
一. Face seal (friction pair) material
The friction pair materials include graphite, ceramics, surfacing cemented carbide, tungsten carbide alloy, SiC, filled PTFE, tin bronze, steel-bonded cemented carbide, stainless steel, phenolic plastic, nylon, etc. The properties of commonly used materials are as follows:
1.Tungsten carbide alloy is made of metal carbides with high hardness and high melting point such as tungsten carbide and titanium carbide, which are pressed and sintered by powder metallurgy with a binder. 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 auxiliary material for end face seals.
2. Graphite: The advantages of graphite are good corrosion resistance and self-lubrication, small friction coefficient, good thermal shock resistance and easy processing. The disadvantage is that the mechanical strength is low and there are pores. These two shortcomings of graphite can be improved by impregnation and carburizing. Impregnated graphite can be divided into two types: impregnated resin and impregnated metal. Resin-impregnated graphite has good corrosion resistance, but not high temperature resistance (temperature resistance is about 170-200 °C); impregnated metal graphite has good temperature resistance (high temperature resistance of dipped bronze, aluminum, lead, etc. can reach 400~500 °C), but corrosion resistance Bad sex. Graphite is the most widely used non-metallic material, used as the dynamic ring of low-speed mechanical seal and the static ring of high-speed mechanical seal. Good graphite is dense to the naked eye, and the fingers are not powdered or blackened.
3. Ceramics: The advantages of ceramics are good corrosion resistance, high hardness, and good wear resistance. The disadvantage is that they are brittle and hard to process. The most common applications are alumina ceramics and cermets. Ceramics are mostly used in corrosive media, medium and low speed occasions.
4. Surfacing hard alloy on the sealing surface of carbon steel, chromium steel and chromium-nickel steel, the advantages are high hardness, good wear resistance, good temperature resistance (below 500 ℃), corrosion resistance or Good cavitation, but the disadvantage is that it is easy to produce pores, slag inclusion and uneven surface hardness.
二. The material of the auxiliary sealing ring
The requirements for auxiliary sealing materials are good elasticity, small friction coefficient, good wear resistance, heat resistance and low temperature resistance, resistance to medium corrosion, dissolution and aging, etc. In addition, it is also required to have good residual deformation after compression and long-term use. Commonly used auxiliary sealing ring materials are rubber and teflon, in addition to soft polyvinyl chloride.
1.Polytetrafluoroethylene: The advantages of polytetrafluoroethylene are chemical stability, oil resistance, dissolution resistance, moisture resistance, low friction coefficient, and suitable for various corrosive media. The disadvantage is that the elasticity is worse than that of rubber, and it is easy to produce permanent deformation.
2.Rubber: Rubber has good elasticity, cushioning, vibration absorption, heat resistance and corrosion resistance. The rubber sealing ring has a good sealing effect and is the most widely used. Commonly used rubbers include silicone rubber, nitrile rubber, neoprene and fluororubber.
三. Elastic element material
1. Spring material: The requirements for spring material are: good elasticity and medium corrosion resistance. Commonly used spring materials are stainless spring steel (1Cr18Ni9Ti, etc.), chrome steel (3Cr13, 4Cr13, etc.), carbon cable spring steel (60si2Mn, etc.) and phosphor bronze.
2. The requirements for bellows materials are: good welding performance, greater elasticity, and certain corrosion resistance. Commonly used bellows materials include iron-based, copper-based and nickel-based alloys and titanium materials. Generally, nickel-chromium austenitic strips in titanium-based are mainly used, especially 1Cr18Ni12Mo2Ti is used the most. High-nickel elastic alloys are considered to be ideal materials for making bellows, and aluminum-containing materials will encounter difficulties when using general welding techniques. At present, the most widely used bellows material abroad is AM350 (approximately Cr16Ni45MnMo3N), which belongs to solid solution, low strength, low hardness and high elongation.