On the fabrication and mechanical properties of Si3N4 ceramics with low content sintering additives

Abstract Si 3 N 4 ceramics were prepared by hot pressing (HP) and spark plasma sintering (SPS) methods using low content (5 mol%) Al 2 O 3 –RE 2 O 3 (RE = Y, Yb, and La)–SiO 2 /TiN as sintering additives/secondary additives. The effects of sintering additives and sintering methods on the composition, microstructures, and mechanical properties (hardness and fracture toughness) were investigated. The results show that fully density Si 3 N 4 ceramics could be fabricated by rational tailoring of sintering additives and sintering method, and TiN secondary additive could promote the density during HP and SPS. Besides, SN‐AYS‐SPS possesses the most competitive mechanical properties among all the as‐prepared ceramics with the Vickers hardness as 17.31 ± .43 GPa and fracture toughness as 11.07 ± .48 MPa m 1/2 .