New route to improve the flexural strength of silicon nitride ceramics by introducing tungsten carbide nanoparticles

Abstract Silicon nitride (Si ₃ N ₄ ) ceramics containing various tungsten carbide ( WC ) content were prepared by spark plasma sintering ( SPS ) with Al ₂ O ₃ and Y ₂ O ₃ as sintering aids, and WC nanoparticles were introduced via the mechanical ball milling method in the present work. The influence of WC nanoparticles’ content on the densification, microstructure, and mechanical properties of such ceramics was investigated. The results showed that the incorporation of WC nanoparticles promoted the densification of Si ₃ N ₄ ceramics and the growth of β‐Si ₃ N ₄ grains. In comparison with the specimen without WC nanoparticles (879.9 MP a), the flexural strength of the specimens containing WC nanoparticles increased markedly; a maximum flexural strength of 1367.7 MP a can be achieved at the sintering temperature of 1550°C and the milling time of 36 hours.