Silicon nitride (Si₃N₄) is the ceramic you choose when a part needs to be strong, tough and light all at once. With a density of only 3.2 g/cm³, flexural strength of 700–900 MPa and fracture toughness of 6–8 MPa·m^1/2, it outperforms most metals on a specific-strength basis while surviving thermal shocks that would crack alumina or zirconia.
Those properties explain its dominance in hybrid bearing balls, turbocharger rotors, gas-turbine blades and automotive engine components. In the semiconductor industry it appears in wafer handling and lift pins where stiffness, low contamination and thermal cycling capability are simultaneously required.