Silicon Nitride (Si3N4) and Sialons


© Fraunhofer IKTS
Ball bearings made of silicon nitride ceramics.

Silicon nitride (Si3N4) is a non-oxide ceramic material with a unique combination of outstanding properties. These include a high fracture toughness (5-8 MPa·m½) in combination with a high flexural strength (800-1000 MPa) and a low coefficient of thermal expansion (3.5·10-6 K-1). This leads for example to an excellent thermal shock resistance. Furthermore, advanced ceramics are characterized by low density (3.2 g·cm-3), high hardness (12-17 GPa) and high wear resistance. A special feature of silicon nitride is its excellent corrosion and oxidation resistance at high temperatures. Sialon ceramics can be produced to additionally modify the mechanical, thermal and tribological properties. Sialons are formed by the incorporation of aluminum and oxygen into the silicon nitride lattice.

The fields of application of silicon nitride and sialons are manifold, for example used as a material for cutting tools, as advanced ceramics in metal forming, as wear parts for bearing materials or as construction material in machine and plant engineering for extreme mechanical, chemical and thermal stresses. Due to its excellent mechanical properties and biocompatibility, silicon nitride is also interesting for medical technology.


Services offered


  • Adaptation of the material properties of silicon nitride (Si3N4), sialons, aluminum nitride (AlN), titanium nitride (TiN), boron nitride (BN) and composites
  • Adaptation and optimization of mechanical and tribological properties, chemical and high-temperature resistance as well as electrical and thermal conductivity of silicon nitride, sialons, aluminum nitride, titanium nitride, boron nitride and composites
  • Development and testing of prototypes used for applications under mechanical, chemical, thermal und electrical load
  • Concepts for cost optimization
  • Optimization of material properties


Technical equipment


  • Continuous production line from powder preparation and shaping to finishing and characterization
  • Laboratory for mechanical materials testing
  • Equipment for characterizing corrosion behavior in various solutions (alkalis and acids), under normal pressure up to boiling point, hydrothermal corrosion behavior up to 350 °C (pressure up to 200 bar) in water and salt solutions
  • Equipment for characterizing tribosystems (metals, ceramics, plastics, coatings) under defined stress conditions (oscillating sliding wear from room temperature to 600 °C and defined humidity)


Areas of application / references


  • Wear and cutting materials, e.g. bearings (balls, rolling elements), inserts and milling cutters for metalworking
  • Components for chemical plant engineering, metallurgy and forming technology
  • 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 hot plate and other heating elements
  • High thermal-conductivity silicon nitride substrates for power electronics