OBLIQUE IMPACT OF SPHERICAL-PARTICLES ONTO SILICON-NITRIDE

Oblique impact damage to gas-pressure-sintered silicon nitride is investigated by examining changes in the stress field beneath the impact site of the silicon nitride. Varying the impact angle changes the morphologies of the initiated cracks from hertzian cone crack to surface ring crack as the impact angle decreases. Moreover, impact at greater angles (90-degrees and 60-degrees) creates Hertzian cone cracks that drastically decrease the strength of the target materials; impact at smaller angles (45-degrees and 30-degrees), on the other hand, creates surface ring cracks that cause only moderate strength degradation.