Applied in ceramic ball bearings for high-speed spindles and turbine engines with exceptional wear resistance, cutting tool inserts for machining hardened steels and superalloys, engine components such as turbocharger rotors and valve trains for high-temperature operation, biomedical implants including hip and knee replacements offering superior biocompatibility compared to alumina, optical waveguides and integrated photonic devices for telecommunications, wear-resistant coatings for automotive piston rings and cylinder liners, crucibles for molten metal handling in foundries, armor ceramics for ballistic protection in military vehicles, gate dielectrics in CMOS transistors for semiconductor devices, and refractory materials for furnace linings. Silicon nitride combines high fracture toughness, oxidation resistance up to 1400°C, and low thermal expansion coefficient for demanding structural and electronic applications.