Silicon Nitride (Si3N4) and Sialons

Topic

Silicon Nitride (Si3N4) and Sialons

Topic

© Fraunhofer IKTS
Silicon nitride (Si3N4) bearing balls, Fraunhofer IKTS.

Silicon nitride Si3N4 is a non-oxide ceramic with a unique combination of material properties. These include an exceptionally high fracture toughness (5-8 MPa·m½) in conjunction with a high flexural strength (800-1000 MPa) and a low coefficient of thermal expansion (3,5·10-6 K-1). This results in an excellent thermal shock resistance. Further, silicon nitride is characterized by a low density (3,2 g·cm-3), high hardness  (12-17 GPa) and wear resistance. A special feature of silicon nitride is its excellent corrosion and oxidation resistance at high temperatures.

Silicon nitride ceramics usually contain sintering additives. Due to the specific choice of the additives many material properties can be deliberately changed in wide ranges. Sialons are formed by the incorporation of aluminum and oxygen in the silicon-nitride lattice. This allows the modification of mechanical, thermal as well as the tribological properties.

Silicon nitride and sialons are used as a material for cutting tools, as wear parts (e.g. bearing materials) as well as construction material in machine and plant engineering for extreme mechanical, chemical and thermal stresses. Further silicon nitride is a superior biomaterial and is used for biomedical applications.

 

Services offered

 

  • Adaptation of the material properties of silicon nitride, sialons, aluminum nitride (AlN), titanium nitride (TiN), boron nitride (BN) and composite materials in terms of mechanical and tribological properties, electrical and thermal conductivity, corrosion and high temperature resistance
  • Development and testing of prototypes for applications in mechanical, chemical, thermal and electrical stresses
  • Concepts for cost optimization of ceramic raw materials, materials and components especially for nitride ceramics

 

Technical equipment

 

  • Complete material and component manufacturing technology (from Processes and Components to Sintering and Characterization)
  • Application oriented characterization (hot and liquid phase corrosion, friction and wear, mechanical testing)
  • Closed ceram-technological process chain in Inert gas Glovebox system (N2, ≤ 1 ppm O2 , ≤ 1 ppm H2O)

 

Areas of application/references

 

  • Wear and cutting materials (e.g. heavy-duty bearings , inserts and milling cutters for metalworking )
  • Silicon nitride components for industrial applications such as chemical and process industries, metallurgy and metal forming
  • High-temperature materials with special oxidation and corrosion protection for applications in energy technology (hot gas turbine) and engine construction (ceramic glow plug, turbocharger)
  • Ceramic hob and other heating systems