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Particle Impact Damage in Silicon Nitride
Author(s) -
Shockey Donald A.,
Rowcliffe David J.,
Dao Kim C.,
Seaman Lynn
Publication year - 1990
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1990.tb09804.x
Subject(s) - materials science , composite material , cracking , silicon carbide , tungsten carbide , tungsten , silicon nitride , stress (linguistics) , particle (ecology) , layer (electronics) , metallurgy , linguistics , philosophy , oceanography , geology
The evolution of particle‐impact‐induced fracture damage in hot‐pressed (HP) silicon nitride was established by accelerating single 2.4‐mm‐diameter tungsten carbide spheres against polished HP Si 3 N 4 surfaces. Threshold velocities for ring, cone, and radial cracks were determined and the corresponding threshold stress for ring cracking was obtained from an elastic stress analysis. Particle size had significant effects on the threshold velocities for the inelastic impression and the various crack types. Loading rate had little effect on the threshold stress for ring cracks; rate effects on other crack types could not be assessed because the quasistatic indenter failed at stresses less than those required to invoke other crack types. A 20‐μm‐thick oxide scale had little influence on morphology and extent of damage but was removed easily at low velocities, suggesting higher erosion rates for Si 3 N 4 in oxidizing environments. Damage phenomenology in 85% dense reaction‐bonded Si 3 N 4 was similar to that in HP material; however, all stages of damage occurred at substantially lower velocities.