Gas-Pressure Sintered Silicon Nitride

High-strength ceramic for turbocharger rotors and bearings.

Core Principles & Analysis

• Densification is done under nitrogen overpressures up to about 10 MPa near 1,800 °C to keep the Si3N4 from decomposing before it sinters.
• Interlocking elongated beta-grains give it the highest fracture toughness of the common monolithic engineering ceramics.
• Silicon nitride balls, at roughly 40% the density of steel, run in hybrid machine-spindle bearings and flew in Space Shuttle main engine turbopumps.

Specifications & Metrics

• DENSITY: 3.20 g/cm³
• YIELD STRENGTH: 800 MPa (flexural)
• HARDNESS: 1,500 HV