Silican Carbide Mechanical Seals

Silicon carbide is the ideal sealing material. It has good corrosion resistance, higher mechanical intensity, excellent resisting wear ability and high temperature, good self-lubricity and making-group, low friction factor, good heat-conduction and so on. Therefore, silicon carbide mechanical seals also possess the property of excellent resistant-corrosion, high mechanical strength, high thermal conductivity and good self-lubrication. Silicon carbide seals are widely used in many different industries, including spacecraft, machinery, metallurgy, printing and dyeing, foodstuff, pharmaceutical, auto industry etc.

Why make from silicon carbide?
Silicon carbide is a more expensive seals material with the carbon, but it is often used in more demanding applications. For example, blistering is a critical concern with carbon bearing materials. Strangely, the reason why blistering sometimes occurs is not known for certain. The most popular explanation is that a certain amount of material becomes absorbed in the carbon substrate and expands because of frictional heat, thus creating a crater in the seals face. Blistering is most often found in applications involving heavy oils. In some cases, the use of silicon carbide as a mating surface will eliminate a blistering problem.

Silicon Carbide (SiC) physical property
Technical parameter Unit RBSiC SSiC SiC+C SSiC+C QSSiC+C
Content of Sic % ≥90 ≥98 ≥85 ≥92 ≥90
Free Si % ≤10 ≤1 ≤12 / /
Elastic Modulus GPa ≥400 ≥410 ≥350 ≥360 ≥180
Temperature °C 1300 1400 1300 1400 1400
Hardness HS 110 115 ≥105 ≥110 ≥100
Porosity Rate % <0.3 <0.2 <0.5 <0.5 <5
Density g/cm3 3.00~3.05 >3.10 2.69-2.90 2.70-3.0 2.65
Compressive Strength MPa >2200 >2500 >1400 >1600 >800
Fractural Strength MPa >350 >380 >150 >160 >100
Coefficient of Heat Expansion 10-6/°C 4 4.2 3.50 3.00 2.50

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