29 Sep 2014
September 29, 2014

Silicon Nitride(Si3N4)Ceramics

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Silicon NitrideSi3N4Ceramics

Introduction of Silicon Nitride Ceramics

Silicon nitride, especially high-purity silicon nitride, has very high strength, and is one of the world’s hardest substances. It is extremely heat-resistant, and the strength can always maintain up to the temperature as high as 1200 ℃ without dropping, and will not melt into the melt when heated. It has amazing resistance to chemical corrosion, and is also a high-performance electrical insulating material.


   Diameter: Φ1mm~Φ300mm     Length:<600mm

Silicon nitride ceramics have excellent comprehensive performance and a wide range of application prospects.

  1. Silicon nitride ceramics have strong corrosion resistance, and can be used in strong acid and alkali. They are soluble in hydrofluoric acid, and except for that, they can not react with other inorganic acids (reaction equation: Si3N4 +4 HF +9 H2O ===== 3H2SiO3 (precipitation ) +4 NH4F).
  2. Silicon nitride ceramics are extremely heat-resistant. At 1200℃, the strength and the hardness are almost constant. They can be used in high-temperature environments, will not melt into the melt when heated, and will decompose until up to 1900 ℃.
  3. With non-magnetic property, electrical insulation and low thermal conductivity, they can be used for thermal insulation materials.
  4. They are low in density (3.26g/cm3), light in weight, and far higher than the general ceramic materials in the strength and hardness, so can be used as wear-resistant materials.
  5. They have lower thermal expansion coefficient (3.2 × 10-6 / K), equivalent to 30% of alumina ceramic and less than 40% of zirconia ceramic, and can withstand rapid changes. When heated to 1 000 ℃ or above in air, then rapidly cooled and sharply heated, it will not shatter.



Silicon NitrideSi3N4Ceramic Characteristics

Densityg/cm3 Relative density% Elastic modulusGPa Bending strengthMPa HardnessGPa
3.260.02 >99.5 300~320 900~1000 18 – 20
Fracture toughness/MPa•m1/2 Specific resistance ratio Poisson’s ratio Linear expansion coefficient10-6K-1 Webuller modulus
7.0~9.0 1018 0.25 3.1~3.3 12~15
Thermal conductivityW•(m•K)-1 Thermal shock resistance  Corrosion resistance Size stability Magnetic
15~20 Excellent Excellent Excellent NO