Fracture Toughness of Si3N4 Based Ceramics with Rare-Earth Oxide Sintering Additives
Fracture toughness of hot-pressed silicon nitride and Si3N4+SiC nanocomposites prepared with different rare-earth oxides (La2O3, Sm2O3, Y2O3, Yb2O3, Lu2O3) sintering additives have been investigated by Chevron Notched Beam, Indentation Strength and Indentation Fracture techniques. The fracture toughness values of composites were lower due to the finer microstructures and the lack of toughening mechanisms. In the Si3N4 with higher aspect ratio (Lu or Yb additives) crack deflection occurred more frequently compared to the Si3N4 doped with La or Y, which was responsible for the higher fracture toughness.
J. Dusza, R. Danzer, R. Morrell and G.D. Quinn
P. Tatarko et al., "Fracture Toughness of Si3N4 Based Ceramics with Rare-Earth Oxide Sintering Additives", Key Engineering Materials, Vol. 409, pp. 377-381, 2009