Tailoring mechanical and tribological properties of Si3N4 ceramics by synergistic strengthening from nano-TiN and aligned SiCw

The inherent brittleness of silicon nitride (Si 3 N 4 ) ceramics limits their practical applications, as enhancing fracture toughness often compromises mechanical strength. Achieving a simultaneous enhancement in both strength and toughness remains a major challenge. In response, we developed high-performance Si 3 N 4 ceramic composites via a combined freeze-drying and hot-pressing strategy, incorporating nano titanium nitride (nano-TiN) particles and directionally aligned silicon carbide whiskers (SiCw) as reinforcing agents. These reinforcements were uniformly distributed within the ceramic matrix, leading to a marked improvement in both mechanical properties and microstructural integrity. Notably, the composite containing 5 wt.% nano-TiN and 9 wt.% SiCw exhibited the most optimized performance, with the bending strength enhanced by 45% and the fracture toughness increased by 69% compared to unreinforced Si 3 N 4 ceramics. In addition, the incorporation of these well-designed reinforcements significantly improved wear resistance of the ceramic. This study offers a promising route for developing high-performance Si 3 N 4 and other structural ceramics.