HERTZIAN FRACTURE OF TEXTURED Si_3N_4

摘要

The Hertzian fracture behavior of a fine grained silicon nitride with an aligned microstructure was investigated. Fracture toughness anisotropy has previously been related to quantitative texture analysis in silicon nitride and ceramic composites using Vickers indentation. Indentation with hard spheres on hot pressed and plane-strain forged silicon nitrides on varying surface orientations results in profound demonstrations of crack initiation and propagation. Crack initiation was observed to occur at orientations of lowest toughness followed by completion of surface cracking at higher loads.