Silicon nitride nanoceramics densified by dynamic grain sliding

The densification behaviors of two silicon nitride nanopowder mixtures based respectively on alpha-Si3N4 and beta-Si3N4 as the major phase constituent were studied by spark plasma sintenng Sintering conditions were established where a low viscous liquid not in equilibrium with the main crystalline constituent(s) stimulated the grain sliding yet did not activate the reprecipitation mechanism that unavoidably yields grain growth By this way of dynamic gram sliding full densification of silicon nitride nanoceramics was achieved with no noticeable involvement of alpha- to beta-Si3N4 phase transformation and grain growth This processing principle opens the way toward flexible and precise tailoring of the microstructures and properties of Si3N4 ceramics The obtained silicon nitride nanoceramics showed improved wear resistance, particularly under higher Hertzian stresses